Bioinspired polydopamine sheathed nanofibers for high-efficient in vivo solid-phase microextraction of pharmaceuticals in fish muscle.

PubMed

Xu, Jianqiao; Huang, Shuyao; Wu, Rongben; Jiang, Ruifen; Zhu, Fang; Wang, Jing; Ouyang, Gangfeng

2015-03-17

In this study, electrospun nanofibers were used as solid-phase microextraction (SPME) fiber coatings after substituting the water-soluble sheath of the emulsion electrospun polystyrene (PS)@Plurinic F-127 core-sheath nanofibers with biocompatible and water-stable polydopamine (PDA) and subsequently being appropriately cross-linked with glutaraldehyde (GA) to enhance the strength of the electrospun architecture. The novel custom-made PS@PDA-GA coating was wettable in aqueous solutions and thus exhibited much higher extraction efficiency than the nonsheathed PS nanofiber coating and the thicker polydimethylsiloxane (PDMS) coating. The novel coating also possessed excellent stability (relative standard deviations (RSDs) less than 7.3% for six sampling-desorption cycles), interfiber reproducibility (RSDs less than 14.3%), and antibiofouling ability, which were beneficial for in vivo sampling. The PS@PDA-GA fiber was used to monitor pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities with the limits of detection in the range of 1.1 (mefenamic acid) to 8.9 (fluoxetine) ng·g(-1) and comparable accuracies to liquid extraction were achieved. In general, this study explored a convenient and effective method to sheath nanofibers for high-efficient in vivo SPME of analytes of interest in semisolid tissues.

Polydimethylsiloxane/MIL-100(Fe) coated stir bar sorptive extraction-high performance liquid chromatography for the determination of triazines in environmental water samples.

PubMed

Lei, Yun; Chen, Beibei; You, Linna; He, Man; Hu, Bin

2017-12-01

Polydimethylsiloxane (PDMS)/MIL-100(Fe) coated stir bar was prepared by sol gel technique, and good preparation reproducibility was achieved with relative standard deviations (RSDs) ranging from 2.6% to 7.5% (n=7) and 3.6% to 10.8% (n=7) for bar-to-bar and batch-to-batch, respectively. Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/MIL-100(Fe) stir bar showed better extraction efficiency for target triazines compounds. It also exhibited relatively fast extraction/desorption kinetics and long lifespan. Based on it, a method of PDMS/MIL-100(Fe) coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for the determination of six triazines (simazine, atrazine, prometon, ametryn, prometryne and prebane) in environmental water samples. Several parameters affecting SBSE of six target triazines including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.021-0.079μgL -1 . The repeatability RSDs were in the range of 2.3-6.3% (n=7, c=0.5μgL -1 ) and the enrichment factors (EFs) ranged from 51.1 to 102-fold (theoretical EF was 200-fold). The proposed method was applied to the analysis of target triazines in environmental water samples, with recoveries of 98.0-118% and 94.0-107% for spiked East Lake water and local pond water samples, respectively. Copyright © 2017. Published by Elsevier B.V.

Polyaniline/cyclodextrin composite coated stir bar sorptive extraction combined with high performance liquid chromatography-ultraviolet detection for the analysis of trace polychlorinated biphenyls in environmental waters.

PubMed

Lei, Yun; He, Man; Chen, Beibei; Hu, Bin

2016-04-01

A novel polyaniline/α-cyclodextrin (PANI/α-CD) composite coated stir bar was prepared by sol-gel process for the analysis of polychlorinated biphenyls (PCBs) in this work. The preparation reproducibility of the PANI/α-CD-coated stir bar was good, with relative standard deviations (RSDs) ranging from 2.3% to 3.7% (n=7) and 2.0% to 3.8% (n=7) for bar to bar and batch to batch, respectively. Based on it, a novel method of PANI/α-CD-coated stir bar sorptive extraction (SBSE) followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection was developed for the determination of trace PCBs in environmental waters. To obtain the best extraction performance for target PCBs, several parameters affecting SBSE, such as extraction time, stirring rate, and ionic strength were investigated. Under optimal experimental conditions, the limits of detection (LODs) of the proposed method for seven PCBs were in the range of 0.048-0.22 μg/L, and the RSDs were 5.3-9.8% (n=7, c=1 μg/L). Enrichment factors (EFs) ranging from 39.8 to 68.4-fold (theoretical EF, 83.3-fold) for target analytes were achieved. The proposed method was successfully applied for the determination of seven target PCBs in Yangtze River water and East Lake water, and the recoveries were in the range of 73.0-120% for the spiked East Lake water samples and 82.7-121% for the spiked Yangtze River water samples, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Systematic comparison of static and dynamic headspace sampling techniques for gas chromatography.

PubMed

Kremser, Andreas; Jochmann, Maik A; Schmidt, Torsten C

2016-09-01

Six automated, headspace-based sample preparation techniques were used to extract volatile analytes from water with the goal of establishing a systematic comparison between commonly available instrumental alternatives. To that end, these six techniques were used in conjunction with the same gas chromatography instrument for analysis of a common set of volatile organic carbon (VOC) analytes. The methods were thereby divided into three classes: static sampling (by syringe or loop), static enrichment (SPME and PAL SPME Arrow), and dynamic enrichment (ITEX and trap sampling). For PAL SPME Arrow, different sorption phase materials were also included in the evaluation. To enable an effective comparison, method detection limits (MDLs), relative standard deviations (RSDs), and extraction yields were determined and are discussed for all techniques. While static sampling techniques exhibited sufficient extraction yields (approx. 10-20 %) to be reliably used down to approx. 100 ng L(-1), enrichment techniques displayed extraction yields of up to 80 %, resulting in MDLs down to the picogram per liter range. RSDs for all techniques were below 27 %. The choice on one of the different instrumental modes of operation (aforementioned classes) was thereby the most influential parameter in terms of extraction yields and MDLs. Individual methods inside each class showed smaller deviations, and the least influences were observed when evaluating different sorption phase materials for the individual enrichment techniques. The option of selecting specialized sorption phase materials may, however, be more important when analyzing analytes with different properties such as high polarity or the capability of specific molecular interactions. Graphical Abstract PAL SPME Arrow during the extraction of volatile analytes from the headspace of an aqueous sample.

Spectrophotometric and fluorimetric determination of diazepam, bromazepam and clonazepam in pharmaceutical and urine samples

NASA Astrophysics Data System (ADS)

Salem, A. A.; Barsoum, B. N.; Izake, E. L.

2004-03-01

New spectrophotometric and fluorimetric methods have been developed to determine diazepam, bromazepam and clonazepam (1,4-benzodiazepines) in pure forms, pharmaceutical preparations and biological fluid. The new methods are based on measuring absorption or emission spectra in methanolic potassium hydroxide solution. Fluorimetric methods have proved selective with low detection limits, whereas photometric methods showed relatively high detection limits. Successive applications of developed methods for drugs determination in pharmaceutical preparations and urine samples were performed. Photometric methods gave linear calibration graphs in the ranges of 2.85-28.5, 0.316-3.16, and 0.316-3.16 μg ml -1 with detection limits of 1.27, 0.08 and 0.13 μg ml -1 for diazepam, bromazepam and clonazepam, respectively. Corresponding average errors of 2.60, 5.26 and 3.93 and relative standard deviations (R.S.D.s) of 2.79, 2.12 and 2.83, respectively, were obtained. Fluorimetric methods gave linear calibration graphs in the ranges of 0.03-0.34, 0.03-0.32 and 0.03-0.38 μg ml -1 with detection limits of 7.13, 5.67 and 16.47 ng ml -1 for diazepam, bromazepam and clonazepam, respectively. Corresponding average errors of 0.29, 4.33 and 5.42 and R.S.D.s of 1.27, 1.96 and 1.14 were obtained, respectively. Statistical Students t-test and F-test have been used and satisfactory results were obtained.

Simultaneous determination of five marker constituents in Ssanghwa tang by HPLC/DAD

PubMed Central

Won, Jin Bae; Ma, Jin Yeul; Um, Young Ran; Ma, Choong Je

2010-01-01

A HPLC-DAD method was established for the simultaneous evaluation of five bioactive compounds in Ssanghwa tang (SHT) including glycyrrhizin, paeoniflorin, cinnamic acid, decursin and 6-gingerol. These compounds were separated in less than 40 min using a Dionex C18 column with a gradient elution system of water and methanol at a flow rate of 1 ml/min. Calibration curve of standard components presented excellent linear regression (R2 > 0.9903) within the test range. Limit of detection and limit of quantification varied from 0.07 to 0.46 μg/ml and 0.13 to 1.11 μg/ml, respectively. The relative standard deviations (RSDs) of data of the intraday and interday experiments were less than 3.67 and 5.73%, respectively. The accuracy of recovery test ranged from 95.98 to 105.88% with RSD values 0.10– 4.82%. PMID:20668576

[Determination of arbutin in apple juice concentrate by ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry].

PubMed

Kong, Xianghong; He, Qiang; Yue, Aishan; Wu, Shuangmin; Li, Jianhua

2010-06-01

An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) method was developed for the determination of arbutin in apple juice concentrate. Samples were diluted with water, then cleaned-up with a PS-DVB column. Quantitation was carried out using an external standard method. UPLC was performed on an Eclipse Plus C, column (100 mm x 2.1 mm, 1.8 microm) using a gradient solvent system (methanol-water). MS/MS was performed with multiple reaction monitoring (MRM) mode. The detection limit of arbutin was 0.02 mg/L. The method showed good linear relationship at the range of 0.04-2.0 mg/L. The recoveries ranged from 75.2% to 102.7% with relative standard deviations (RSDs) less than 8.9%. The method is simple, fast and sensitive. It's suitable for quantitative and qualitative analysis of arbutin in apple juice concentrate.

Analysis of pharmaceutical and other organic wastewater compounds in filtered and unfiltered water samples by gas chromatography/mass spectrometry

USGS Publications Warehouse

Zaugg, Steven D.; Phillips, Patrick J.; Smith, Steven G.

2014-01-01

Research on the effects of exposure of stream biota to complex mixtures of pharmaceuticals and other organic compounds associated with wastewater requires the development of additional analytical capabilities for these compounds in water samples. Two gas chromatography/mass spectrometry (GC/MS) analytical methods used at the U.S. Geological Survey National Water Quality Laboratory (NWQL) to analyze organic compounds associated with wastewater were adapted to include additional pharmaceutical and other organic compounds beginning in 2009. This report includes a description of method performance for 42 additional compounds for the filtered-water method (hereafter referred to as the filtered method) and 46 additional compounds for the unfiltered-water method (hereafter referred to as the unfiltered method). The method performance for the filtered method described in this report has been published for seven of these compounds; however, the addition of several other compounds to the filtered method and the addition of the compounds to the unfiltered method resulted in the need to document method performance for both of the modified methods. Most of these added compounds are pharmaceuticals or pharmaceutical degradates, although two nonpharmaceutical compounds are included in each method. The main pharmaceutical compound classes added to the two modified methods include muscle relaxants, opiates, analgesics, and sedatives. These types of compounds were added to the original filtered and unfiltered methods largely in response to the tentative identification of a wide range of pharmaceutical and other organic compounds in samples collected from wastewater-treatment plants. Filtered water samples are extracted by vacuum through disposable solid-phase cartridges that contain modified polystyrene-divinylbenzene resin. Unfiltered samples are extracted by using continuous liquid-liquid extraction with dichloromethane. The compounds of interest for filtered and unfiltered sample types were determined by use of the capillary-column gas chromatography/mass spectrometry. The performance of each method was assessed by using data on recoveries of compounds in fortified surface-water, wastewater, and reagent-water samples. These experiments (referred to as spike experiments) consist of fortifying (or spiking) samples with known amounts of target analytes. Surface-water-spike experiments were performed by using samples obtained from a stream in Colorado (unfiltered method) and a stream in New York (filtered method). Wastewater spike experiments for both the filtered and unfiltered methods were performed by using a treated wastewater obtained from a single wastewater treatment plant in New York. Surface water and wastewater spike experiments were fortified at both low and high concentrations and termed low- and high-level spikes, respectively. Reagent water spikes were assessed in three ways: (1) set spikes, (2) a low-concentration fortification experiment, and (3) a high-concentration fortification experiment. Set spike samples have been determined since 2009, and consist of analysis of fortified reagent water for target compounds included for each group of 10 to18 environmental samples analyzed at the NWQL. The low-concentration and high-concentration reagent spike experiments, by contrast, represent a one-time assessment of method performance. For each spike experiment, mean recoveries ranging from 60 to 130 percent indicate low bias, and relative standard deviations (RSDs) less than ( Of the compounds included in the filtered method, 21 had mean recoveries ranging from 63 to 129 percent for the low-level and high-level surface-water spikes, and had low ()132 percent]. For wastewater spikes, 24 of the compounds included in the filtered method had recoveries ranging from 61 to 130 percent for the low-level and high-level spikes. RSDs were 130 percent) or variable recoveries (RSDs >30 percent) for low-level wastewater spikes, or low recoveries ( Of the compounds included in the unfiltered method, 17 had mean spike recoveries ranging from 74 to 129 percent and RSDs ranging from 5 to 25 percent for low-level and high-level surface water spikes. The remaining compounds had poor mean recoveries (130 percent), or high RSDs (>29 percent) for these spikes. For wastewater, 14 of the compounds included in the unfiltered method had mean recoveries ranging from 62 to 127 percent and RSDs 130 percent), or low mean recoveries (33 percent) for the low-level wastewater spikes. Of the compounds found in wastewater, 24 had mean set spike recoveries ranging from 64 to 104 percent and RSDs Separate method detection limits (MDLs) were computed for surface water and wastewater for both the filtered and unfiltered methods. Filtered method MDLs ranged from 0.007 to 0.14 microgram per liter (μg/L) for the surface water matrix and from 0.004 to 0.62 μg/L for the wastewater matrix. Unfiltered method MDLs ranged from 0.014 to 0.33 μg/L for the surface water matrix and from 0.008 to 0.36 μg/L for the wastewater matrix.

Development of a fast and sensitive method for measuring multiple neonicotinoid insecticide residues in soil and the application in parks and residential areas.

PubMed

Zhou, Ying; Lu, Xiaoxia; Fu, Xiaofang; Yu, Bo; Wang, Dan; Zhao, Cheng; Zhang, Qi; Tan, Ying; Wang, Xinyi

2018-08-03

A method for simultaneous measure of nine neonicotinoid insecticide residues in soil was developed by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with a quick pretreatment procedure. The soil was extracted with a mixture of acetonitrile and dichloromethane (1:2, v:v) and cleaned up with Primary Secondary Amine (PSA). Matrix-matched standards were prepared to eliminate the interference of the matrix. The LC-MS/MS conditions were optimized to separate the nine neonicotinoids within 6.7 min, and the obtained limits of detection (LODs) and limits of quantification (LOQs) ranged from 0.01 to 0.84 ng g -1 and 0.05-2.79 ng g -1 , respectively. Recoveries of the studied neonicotinoids (except for nitenpyram) ranged from 79.41 to 100.20% with relative standard deviations (RSDs) less than 10% at spiked levels of 5 ng mL -1 , 100 ng mL -1 and 500 ng mL -1 , and RSDs for the interday and intraday method repeatability were less than 9%. The method was applied to measure neonicotinoid residues in soil samples collected from parks (n = 35) and residential areas (n = 33) in Tianjin, China. Seven neonicotinoids were detected, with imidacloprid being the most frequently detected one, followed by acetamiprid and thiamethoxam. The total concentrations of neonicotinoids in soil ranged from 0.27 to 230.76 ng g -1 in parks and 0.23-132.66 ng g -1 in residential areas. Copyright © 2018 Elsevier B.V. All rights reserved.

Fast microextraction of phthalate acid esters from beverage, environmental water and perfume samples by magnetic multi-walled carbon nanotubes.

PubMed

Luo, Yan-Bo; Yu, Qiong-Wei; Yuan, Bi-Feng; Feng, Yu-Qi

2012-02-15

In this work, magnetic carbon nanotubes (CNTs) were prepared by mixing the magnetic particles and multi-walled carbon nanotubes dispersed solutions. Due to their excellent adsorption capability towards hydrophobic compounds, the magnetic CNTs were used as adsorbent of magnetic solid-phase extraction (MSPE) to extract phthalate acid esters (PAEs), which are widely used in many consumable products with potential carcinogenic properties. By coupling MSPE with gas chromatography/mass spectrometry (GC/MS), a rapid, sensitive and cost-effective method for the analysis of PAEs was established. Our results showed that the limits of detection (LODs) of 16 PAEs ranged from 4.9 to 38 ng L(-1), which are much lower compared to the previously reported methods. And good linearities of the detection method were obtained with correlation coefficients (R(2)) between 0.9821 and 0.9993. In addition, a satisfying reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 11.7% and 14.6%, respectively. Finally, the established MSPE-GC/MS method was successfully applied to the determination of PAEs from bottled beverages, tap water and perfume samples. The recoveries of the 16 PAEs from the real samples ranged from 64.6% to 125.6% with the RSDs less than 16.5%. Taken together, the MSPE-GC/MS method developed in current study provides a new option for the detection of PAEs from real samples with complex matrices. Copyright © 2012 Elsevier B.V. All rights reserved.

Zirconium(IV) functionalized magnetic nanocomposites for extraction of organophosphorus pesticides from environmental water samples.

PubMed

Jiang, Li; Huang, Tengjun; Feng, Shun; Wang, Jide

2016-07-22

The widespread use of organophosphate pesticides (OPPs) in agriculture leads to residue accumulation in the environment which is dangerous to human health and disrupts the ecological balance. In this work, one nanocomposite immobilized zirconium (Zr, IV) was prepared and used as the affinity probes to quickly and selectively extract organophosphorus pesticides (OPPs) from water samples. The Fe3O4-ethylenediamine tetraacetic acid (EDTA)@Zr(IV) nanocomposites (NPs) were prepared by simply mixing Zr(IV) ions with Fe3O4-EDTA NPs synthesized by one-pot chemical co-precipitation method. The immobilized Zr(IV) ions were further utilized to capture OPPs based on their high affinity for the phosphate moiety in OPPs. Coupled with GC-MS, four OPPs were used as models to demonstrate the feasibility of this approach. Under the optimum conditions, the limits of detection for target OPPs were in the range of 0.10-10.30ngmL(-1) with relative standard deviations (RSDs) of 0.61-4.40% (n=3), respectively. The linear ranges were over three orders of magnitudes (correlation coefficients, R(2)>0.9995). The Fe3O4-EDTA@Zr(IV) NPs were successfully applied to extract OPPs samples with recoveries of 86.95-112.60% and RSDs of 1.20-10.42% (n=3) from two spiked real water. By the proposed method, the matrix interference could be effectively eliminated. We hope our finding can provide a promising alternative for the fast extraction of OPPs from complex real samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of quality-control data collected by the U.S. Geological Survey for routine water-quality activities at the Idaho National Laboratory, Idaho, 1996–2001

USGS Publications Warehouse

Rattray, Gordon W.

2012-01-01

The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, collects surface water and groundwater samples at and near the Idaho National Laboratory as part of a routine, site-wide, water-quality monitoring program. Quality-control samples are collected as part of the program to ensure and document the quality of environmental data. From 1996 to 2001, quality-control samples consisting of 204 replicates and 27 blanks were collected at sampling sites. Paired measurements from replicates were used to calculate variability (as reproducibility and reliability) from sample collection and analysis of radiochemical, chemical, and organic constituents. Measurements from field and equipment blanks were used to estimate the potential contamination bias of constituents. The reproducibility of measurements of constituents was calculated from paired measurements as the normalized absolute difference (NAD) or the relative standard deviation (RSD). The NADs and RSDs, as well as paired measurements with censored or estimated concentrations for which NADs and RSDs were not calculated, were compared to specified criteria to determine if the paired measurements had acceptable reproducibility. If the percentage of paired measurements with acceptable reproducibility for a constituent was greater than or equal to 90 percent, then the reproducibility for that constituent was considered acceptable. The percentage of paired measurements with acceptable reproducibility was greater than or equal to 90 percent for all constituents except orthophosphate (89 percent), zinc (80 percent), hexavalent chromium (53 percent), and total organic carbon (TOC; 38 percent). The low reproducibility for orthophosphate and zinc was attributed to calculation of RSDs for replicates with low concentrations of these constituents. The low reproducibility for hexavalent chromium and TOC was attributed to the inability to preserve hexavalent chromium in water samples and high variability with the analytical method for TOC. The reliability of measurements of constituents was estimated from pooled RSDs that were calculated for discrete concentration ranges for each constituent. Pooled RSDs of 15 to 33 percent were calculated for low concentrations of gross-beta radioactivity, strontium-90, ammonia, nitrite, orthophosphate, nickel, selenium, zinc, tetrachloroethene, and toluene. Lower pooled RSDs of 0 to 12 percent were calculated for all other concentration ranges of these constituents, and for all other constituents, except for one concentration range for gross-beta radioactivity, chloride, and nitrate + nitrite; two concentration ranges for hexavalent chromium; and TOC. Pooled RSDs for the 50 to 60 picocuries per liter concentration range of gross-beta radioactivity (reported as cesium-137) and the 10 to 60 milligrams per liter (mg/L) concentration range of nitrate + nitrite (reported as nitrogen [N]) were 17 percent. Chloride had a pooled RSD of 14 percent for the 20 to less than 60 mg/L concentration range. High pooled RSDs of 40 and 51 percent were calculated for two concentration ranges for hexavalent chromium and of 60 percent for TOC. Measurements from (1) field blanks were used to estimate the potential bias associated with environmental samples from sample collection and analysis, (2) equipment blanks were used to estimate the potential bias from cross contamination of samples collected from wells where portable sampling equipment was used, and (3) a source-solution blank was used to verify that the deionized water source-solution was free of the constituents of interest. If more than one measurement was available, the bias was estimated using order statistics and the binomial probability distribution. The source-solution blank had a detectable concentration of hexavalent chromium of 2 micrograms per liter. If this bias was from a source other than the source solution, then about 84 percent of the 117 hexavalent chromium measurements from environmental samples could have a bias of 10 percent or more. Of the 14 field blanks that were collected, only chloride (0.2 milligrams per liter) and ammonia (0.03 milligrams per liter as nitrogen), in one blank each, had detectable concentrations. With an estimated confidencelevel of 95 percent, at least 80 percent of the 1,987 chloride concentrations measured from all environmental samples had a potential bias of less than 8 percent. The ammonia bias, which may have occurred at the analytical laboratory, could produce a potential bias of 5-100 percent in eight potentially affected ammonia measurements. Of the 11 equipment blanks that were collected, chloride was detected in 4 of these blanks, sodium in 3 blanks, and sulfate and hexavalent chromium were each detected in 1 blank. The concentration of hexavalent chromium in the equipment blank was the same concentration as in the source-solution blank collected on the same day, which indicates that the hexavalent chromium in the equipment blank is probably from a source other than the portable sampling equipment, such as the sample bottles or the source-solution water itself. The potential bias for chloride, sodium, and sulfate measurements was estimated for environmental samples that were collected using portable sampling equipment. For chloride, it was estimated with 93 percent confidence that at least 80 percent of the measurements had a bias of less than 18 percent. For sodium and sulfate, it was estimated with 91 percent confidence that at least 70 percent of the measurements had a bias of less than 12 and 5 percent, respectively.

On the improvement of signal repeatability in laser-induced air plasmas

NASA Astrophysics Data System (ADS)

Zhang, Shuai; Sheta, Sahar; Hou, Zong-Yu; Wang, Zhe

2018-04-01

The relatively low repeatability of laser-induced breakdown spectroscopy (LIBS) severely hinders its wide commercialization. In the present work, we investigate the optimization of LIBS system for repeatability improvement for both signal generation (plasma evolution) and signal collection. Timeintegrated spectra and images were obtained under different laser energies and focal lengths to investigate the optimum configuration for stable plasmas and repeatable signals. Using our experimental setup, the optimum conditions were found to be a laser energy of 250 mJ and a focus length of 100 mm. A stable and homogeneous plasma with the largest hot core area in the optimum condition yielded the most stable LIBS signal. Time-resolved images showed that the rebounding processes through the air plasma evolution caused the relative standard deviation (RSD) to increase with laser energies of > 250 mJ. In addition, the emission collection was improved by using a concave spherical mirror. The line intensities doubled as their RSDs decreased by approximately 25%. When the signal generation and collection were optimized simultaneously, the pulse-to-pulse RSDs were reduced to approximately 3% for O(I), N(I), and H(I) lines, which are better than the RSDs reported for solid samples and showed great potential for LIBS quantitative analysis by gasifying the solid or liquid samples.

Hydrothermally grown and self-assembled modified titanium and nickel oxide composite nanosheets on Nitinol-based fibers for efficient solid phase microextraction.

PubMed

Wang, Huiju; Song, Wenlan; Zhang, Min; Zhen, Qi; Guo, Mei; Zhang, Yida; Du, Xinzhen

2016-10-14

A novel titanium and nickel oxide composite nanosheets (TiO 2 /NiOCNSs) coating was in situ grown on a Nitinol (NiTi) wire by direct hydrothermal treatment and modified by self-assembly of trichlorophenylsilane for solid phase microextraction (SPME). TiO 2 /NiOCNSs were radially oriented and chemically bonded to the NiTi substrate with double-faced open access sites. Moreover the phenyl modified TiO 2 /NiOCNSs (TiO 2 /NiOCNSs-Ph) coating exhibited original surface supporting framework favorable for effective SPME. The extraction performance of TiO 2 /NiOCNSs-Ph coated NiTi (NiTi-TiO 2 /NiOCNSs-Ph) fiber was investigated for the concentration and detection of ultraviolet (UV) filters, polycyclic aromatic hydrocarbons (PAHs), phthalate acid esters and polychlorinated biphenyls coupled to HPLC with UV detection. The novel fiber exhibited better selectivity for UV filters and PAHs and presented greater extraction capability compared to commercial polydimethylsiloxane and polyacrylate fibers. Under the optimized conditions for SPME of UV filters, the proposed method presented linear ranges from 0.1 to 300μg/L with correlation coefficients of higher than 0.999 and limits of detection from 0.030μg/L to 0.064μg/L. Relative standard deviations (RSDs) were below 7.16% and 8.42% for intra-day and inter-day measurements with the single fiber, respectively. Furthermore RSDs for fiber-to-fiber reproducibility from 6.57% to 8.93% were achieved. The NiTi-TiO 2 /NiOCNSs-Ph fiber can be used up to 200 times. The proposed method was successfully applied to the preconcentration and determination of trace target UV filters in different environmental water samples. The relative recoveries from 87.3% to 104% were obtained with RSDs less than 8.7%. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of capillary electrophoresis-mass spectrometry and hydrophilic interaction chromatography-mass spectrometry for anionic metabolic profiling of urine.

PubMed

Kok, Miranda G M; Somsen, Govert W; de Jong, Gerhardus J

2015-01-01

In order to assess the utility of a recently developed capillary electrophoresis-mass spectrometry (CE-MS) method for the study of anionic metabolites in urine, a comparison was made with hydrophilic interaction chromatography-MS (HILIC-MS) using negative electrospray ionization. After optimization of the HILIC conditions, a gradient employing 10mM ammonium acetate (pH 6.8) in acetonitrile-water (5 min 90% acetonitrile followed by 90%-50% acetonitrile in 10 min) was selected, providing baseline separation of five representative anionic test metabolites. Relative standard deviations (RSDs) for HILIC retention times and peak areas were below 0.2% and 7.7%, respectively, and detection limits were in the range 0.04-2.21 μM. Metabolites in rat urine could also be analysed in a reproducible way with retention time and peak area RSDs below 0.6% and 13.6%, respectively. The CE-MS and HILIC-MS methods were compared in terms of reproducibility, sensitivity, selectivity and coverage of the anionic urinary metabolome. In general, peak area RSDs were similar whereas HILIC-MS yielded better retention-time repeatability and up to 80 times lower detection limits (expressed in injected concentration) for test metabolites as compared to CE-MS. Rat urine analysis by HILIC-MS provided detection of 1360 molecular features compared to 347 molecular features revealed with CE-MS. Of these, a number of 144 molecular features were found with both HILIC-MS and CE-MS, which showed on average 10 times higher peak areas in HILIC-MS. The HILIC retention and CE migration times of the common features were clearly not correlated. The HILIC and CE behavior of the test metabolites and 16 putatively identified common features were evaluated involving their physicochemical properties, indicating a markedly different separation selectivity, and thus significant degree of orthogonality of HILIC and CE. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of platinum in waste platinum-loaded carbon catalyst samples using microwave-assisted sample digestion and ICP-OES

NASA Astrophysics Data System (ADS)

Ma, Yinbiao; Wei, Xiaojuan

2017-04-01

A novel method for the determination of platinum in waste platinum-loaded carbon catalyst samples was established by inductively coupled plasma optical emission spectrometry after samples digested by microwave oven with aqua regia. Such experiment conditions were investigated as the influence of sample digestion methods, digestion time, digestion temperature and interfering ions on the determination. Under the optimized conditions, the linear range of calibration graph for Pt was 0 ˜ 200.00 mg L-1, and the recovery was 95.67% ˜ 104.29%. The relative standard deviation (RSDs) for Pt was 1.78 %. The proposed method was applied to determine the same samples with atomic absorption spectrometry with the results consistently, which is suitable for the determination of platinum in waste platinum-loaded carbon catalyst samples.

Enhancing reproducibility of SALDI MS detection by concentrating analytes within laser spot.

PubMed

Teng, Fei; Zhu, Qunyan; Wang, Yalei; Du, Juan; Lu, Nan

2018-03-01

Surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI TOF MS) has become one of the most important analytical methods due to its less interference at low molecular weight range. However, it is still a challenge to obtain a good reproducibility of SALDI TOF MS because of the inhomogeneous distribution of analyte molecules induced by coffee ring effect. We propose a universal and reliable method to eliminate the coffee ring effect by concentrating all the analyte molecules within the laser spot. This method exhibits an excellent reproducibility of spot-to-spot and substrate-to-substrate, and the relative standard deviations (RSDs) for different concentrations are lower than 12.6%. It also performs good linear dependency (R 2 > 0.98) in the log-log plot with the concentration range of 1nM to 1μM, and the limit of detection for R6G is down to 1fmol. Copyright © 2017 Elsevier B.V. All rights reserved.

Acylhydrazone bond dynamic covalent polymer gel monolithic column online coupling to high-performance liquid chromatography for analysis of sulfonamides and fluorescent whitening agents in food.

PubMed

Zhang, Chengjiang; Luo, Xialin; Wei, Tianfu; Hu, Yufei; Li, Gongke; Zhang, Zhuomin

2017-10-13

A new dynamic covalent polymer (DCP) gel was well designed and constructed based on imine chemistry. Polycondensation of 4,4'-biphenyldicarboxaldehyde and 1,3,5-benzenetricarbohydrazide via Schiff-base reaction resulted in an acylhydrazone bond gel (AB-gel) DCP. AB-gel DCP had three-dimensional network of interconnected nanoparticles with hierarchically porous structure. AB-gel DCP was successfully fabricated as a monolithic column by an in-situ chemical bonding method for online enrichment and separation purpose with excellent permeability. AB-gel DCP based monolithic column showed remarkable adsorption affinity towards target analytes including sulfonamides (SAs) and fluorescent whitening agents (FWAs) due to its strong π-π affinity, hydrophobic effect and hydrogen bonding interaction. Then, AB-gel DCP based monolithic column was applied for online separation and analysis of trace SAs and FWAs in food samples coupled with high-performance liquid chromatography (HPLC). Sulfathiazole (ST) and sulfadimidine (SM2) in one positive weever sample were actually found and determined with concentrations of 273.8 and 286.3μg/kg, respectively. 2,5-Bis(5-tert-butyl-2-benzoxazolyl) thiophene (FWA184) was actually quantified in one tea infusion sample with the concentration of 268.5ng/L. The spiked experiments suggested the good recoveries in range of 74.5-110% for SAs in weever and shrimp samples with relative standard deviations (RSDs) less than 9.7% and in range of 74.0-113% for FWAs in milk and tea infusion samples with RSDs less than 9.0%. AB-gel DCP monolithic column was proved to be a promising sample preparation medium for online separation and analysis of trace analytes in food samples with complex matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

Protocol proposal for, and evaluation of, consistency in nicotine delivery from the liquid to the aerosol of electronic cigarettes atomizers: regulatory implications.

PubMed

Farsalinos, Konstantinos E; Yannovits, Nikoletta; Sarri, Theoni; Voudris, Vassilis; Poulas, Konstantinos

2016-06-01

To propose a protocol and evaluate the consistency in nicotine delivery to the aerosol of different types of electronic cigarette (EC) atomizers, as required by regulatory authorities. Three cartomizer and four tank-type atomizer products were tested (three samples per product). The aerosol from three 20-puff sessions from each sample was collected using a smoke machine. Three cartridges from a nicotine inhaler and three tobacco cigarettes were also tested. Analytical laboratory in Greece. Aerosol nicotine levels were measured. Relative standard deviation (RSD, i.e. coefficient of variation) was calculated separately for each cartomizer and replacement atomizer head sample (intrasample RSD) and between different samples (intersample RSD). The percentage difference from the mean, which is used to assess the quality of medicinal nebulizers, was also calculated. The aerosol nicotine levels were 1.01-10.61 mg/20 puffs for ECs, 0.12-0.18 mg/20 puffs for the nicotine inhaler and 1.76-2.20 mg/cigarette for the tobacco cigarettes. The intrasample RSDs were 3.7-12.5% for ECs and 14.3% for the nicotine inhaler and 11.1% for the tobacco cigarettes. The intersample RSDs were higher in cartomizers (range: 6.9-37.8%) compared with tank systems (range: 6.4-9.3%). All tank-type atomizers and one cartomizer were within 75-125% of the mean, as dictated for medicinal nebulizers. Electronic cigarettes that use tank-type atomizers appear to deliver nicotine in more consistent quantities (within the acceptable limits for medicinal nebulizers and similar to the nicotine inhaler) than electronic cigarettes that use cartomizers. The protocol for testing nicotine delivery consistency described in this paper could be used effectively for regulatory purposes. © 2016 Society for the Study of Addiction.

Solid-phase microextraction of phthalate esters in water sample using different activated carbon-polymer monoliths as adsorbents.

PubMed

Lirio, Stephen; Fu, Chung-Wei; Lin, Jhih-Yun; Hsu, Meng-Ju; Huang, Hsi-Ya

2016-07-13

In this study, the application of different activated carbon-polymer (AC-polymer) monoliths as adsorbents for the solid-phase microextraction (SPME) of phthalate esters (PAEs) in water sample were investigated. The activated carbon (AC) was embedded in organic polymers, poly(butyl methacrylate-co-ethylene dimethacrylate) (poly(BMA-EDMA)) or poly(styrene-co-divinylbenzene) (poly(STY-DVB)), via a 5-min microwave-assisted or a 15-min water bath heating polymerization. Preliminary investigation on the performance of the native poly(BMA-EDMA) and poly(STY-DVB) demonstrated remarkable adsorption efficiencies for PAEs. However, due to the strong hydrophobic, π-π, and hydrogen bonding interactions between the analytes and polymers, low extraction recoveries were achieved. In contrast, the presence of AC in native polymers not only enhanced the adsorption efficiencies but also assisted the PAE desorption, especially for AC-poly(STY-DVB) with extraction recovery ranged of 76.2-99.3%. Under the optimized conditions, the extraction recoveries for intra-, inter-day and column-to-column were in the range of 76.5-100.8% (<3.7% RSDs), 77.2-97.6% (<5.6% RSDs) and 75.5-99.7% (<6.2% RSDs), respectively. The developed AC-poly(STY-DVB) monolithic column showed good mechanical stability, which can be reused for more than 30 extraction times without any significant loss in the extraction recoveries of PAEs. The AC-poly(STY-DVB) monolithic column was successfully applied in SPME of PAEs in water sample with extraction recovery ranged of 78.8%-104.6% (<5.5% RSDs). Copyright © 2016 Elsevier B.V. All rights reserved.

Capillary electrophoresis for analyzing pesticides in fruits and vegetables using solid-phase extraction and stir-bar sorptive extraction.

PubMed

Juan-García, Ana; Picó, Yolanda; Font, Guillermina

2005-05-06

Two procedures based on solid-phase extraction (SPE) and stir-bar sorptive extraction (SBSE) in combination with micellar electrokinetic chromatography (MEKC)--diode array detection (DAD) were compared for the simultaneous extraction of acrinathrin, bitertanol, cyproconazole, fludioxonil, flutriafol, myclobutanil, pyriproxyfen, and tebuconazole in lettuce, tomato, grape, and strawberry. Selectivity and resolution of the MEKC procedure were studied changing the pH and the molarity of the buffer, the type and the concentration of surfactant, and the methanol content in the mobile phase. A buffer consisting of 6 mM sodium tetraborate decahydrate with 75 mM of cholic acid sodium solution (pH 9.2) gave the best results. Linearity, extraction efficiencies and limits of quantitation (LOQs) of both extraction methods were compared. The recoveries obtained by SPE ranged from 40 to 106% with relative standard deviations (R.S.D.s) from 10 to 19% whereas by the SBSE method, the recoveries were 12-47% and the R.S.D.s 3-17%. The LOQs were much better by SPE (0.2-0.5 mg kg(-1) depending on the processed sample amount) than those obtained by SBSE (1 mg kg(-1) for each compound). Advantages and disadvantages of both procedures are also discussed. As SPE is more robust, rapid, and sensitive than SBSE, its application in combination with MEKC is recommended because provided LOQs below the MRLs established, which is not always attained by SBSE.

Determination of short chain chlorinated paraffins in water by stir bar sorptive extraction-thermal desorption-gas chromatography-triple quadrupole tandem mass spectrometry.

PubMed

Tölgyessy, P; Nagyová, S; Sládkovičová, M

2017-04-21

A simple, robust, sensitive and environment friendly method for the determination of short chain chlorinated paraffins (SCCPs) in water using stir bar sorptive extraction (SBSE) coupled to thermal desorption-gas chromatography-triple quadrupole tandem mass spectrometry (TD-GC-QqQ-MS/MS) was developed. SBSE was performed using 100mL of water sample, 20mL of methanol as a modifier, and a commercial sorptive stir bar (with 10mm×0.5mm PDMS layer) during extraction period of 16h. After extraction, the sorptive stir bar was thermally desorbed and online analysed by GC-MS/MS. Method performance was evaluated for MilliQ and surface water spiked samples. For both types of matrices, a linear dynamic range of 0.5-3.0μgL -1 with correlation coefficients >0.999 and relative standard deviations (RSDs) of the relative response factors (RRFs) <12% was established. The limits of quantification (LOQs) of 0.06 and 0.08μgL -1 , and the precision (repeatability) of 6.4 and 7.7% (RSDs) were achieved for MilliQ and surface water, respectively. The method also showed good robustness, recovery and accuracy. The obtained performance characteristics indicate that the method is suitable for screening and monitoring and compliance checking with environmental quality standards (EQS, set by the EU) for SCCPs in surface waters. Copyright © 2017 Elsevier B.V. All rights reserved.

Combining supercritical fluid extraction of soil herbicides with enzyme immunoassay analysis.

PubMed

Stearman, G K

2001-10-01

Supercritical fluid extraction (SFE) of soil herbicides followed by enzyme immunoassay analysis (EIA) is explained in a step-by-step process. Extracted herbicides, include 2,4-D, simazine, atrazine, and alachlor. The herbicide, trifluralin was not successfully analyzed by EIA because of crossreacting metabolites. Problems with SFE, including uneven packing of cells, leaks, uneven flow and clogging, can largely be eliminated as the method parameters are optimized. It was necessary to add modifiers including methanol or acetone to the SF CO2 to increase the solubility of the analytes. Detection limits of 2.5 ng/g soil for atrazine and alachlor and 15 ng/g soil for simazine and 2,4-D without concentration of the sample were achieved. Recoveries above 80% and relative standard deviations (RSDs) less than 15% for 2,4-D simazine, atrazine and alachlor were achieved. Atrazine and alachlor recoveries were above 90% with RSDs below 10%. Forty soil samples could be extracted and analyzed in an 8-h day.

Magnetic micro-solid-phase-extraction of polycyclic aromatic hydrocarbons in water.

PubMed

Naing, Nyi Nyi; Yau Li, Sam Fong; Lee, Hian Kee

2016-04-01

A novel sorbent, magnetic chitosan functionalized graphene oxide (MCFG) was synthesized and used in the micro-solid-phase-extraction (μ-SPE) and gas chromatography-mass spectrometric (GC-MS) analysis of polycyclic aromatic hydrocarbons (PAHs) from water. Through the use of the magnetic sorbent, the μ-SPE device also functioned as a stir bar during extraction. Three types of MCFG were prepared using glutaraldehyde cross-linked chitosan and graphene oxide with different amounts of magnetic nanoparticles (Fe3O4) (0.05g, 0.07g and 0.1g). The material was characterized using Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Parameters affecting the extraction such as the type of sorbent, extraction and desorption times, volume of sample solution and type of desorption solvent were optimized. Under the most favourable conditions, the highest extraction was obtained by using the composite prepared with 0.1g of Fe3O4. For the latter material as sorbent, the linearity of the analytes was in the range of 0.01 and 100μgL(-1) for naphthalene, fluoranthene and pyrene while acenaphthylene and phenanthrene exhibited linearity in the range of 0.05 and 100μgL(-1). For fluorene and anthracene, the linearity range was from 0.01 to 50μgL(-1). The coefficients of determination (r(2)) associated with the above linear ranges were higher than 0.987. The limits of detection from GC-MS analysis of the seven PAHs were in the range 0.2-1.8ngL(-1); limits of quantification were between 0.8 and 5.9ngL(-1) while the relative standard deviations (RSDs) varied from 2.1 to 8.2%. The recoveries of the method for the compounds at spiking levels of 1 and 5μgL(-1) were in the range 67.5-106.9% with RSDs below 15%. The enrichment factors were found to be in between 67 and 302. The developed method afforded an interesting and innovative approach using MCFG as an efficient and promising sorbent. Copyright © 2016 Elsevier B.V. All rights reserved.

In situ preparation of multilayer coated capillary column with HKUST-1 for separation of neutral small organic molecules by open tubular capillary electrochromatography.

PubMed

Xu, Yin-Yin; Lv, Wen-Juan; Ren, Cui-Ling; Niu, Xiao-Ying; Chen, Hong-Li; Chen, Xing-Guo

2018-01-12

The popularity of novel nanoparticles coated capillary column has aroused widespread attention of researchers. Metal organic frameworks (MOFs) with special structure and chemical properties have received great interest in separation sciences. This work presents the investigation of HKUST-1 (Hong Kong University of Science and Technology-1, called Cu 3 (BTC) 2 or MOF-199) nanoparticles as a new type of coating material for capillary electrochromatography. For the first time, three layers coating (3-LC), five layers coating (5-LC), ten layers coating (10-LC), fifteen layers coating (15-LC), twenty layers coating(20-LC) and twenty-five layers coating (25-LC) capillary columns coated with HKUST-1 nanoparticles were synthesized by covalent bond with in situ, layer-by-layer self-assembly approach. The results of scanning electron microscopy (SEM), X-ray diffraction (XRD) and plasma atomic emission spectrometry (ICP-AES) indicated that HKUST-1 was successfully grafted on the inner wall of the capillary. The separating performances of 3-LC, 5-LC, 10-LC, 15-LC, 20-LC and 25-LC open tubular (OT) capillary columns were studied with some neutral small organic molecules. The results indicated that the neutral small organic molecules were separated successfully with 10-LC, 15-LC and 20-LC OT capillary columns because of the size selectivity of lattice aperture and hydrophobicity of organic ligands. In addition, 10-LC and 15-LC OT capillary columns showed better performance for the separation of certain phenolic compounds. Furthermore, 10-LC, 15-LC and 20-LC OT capillary columns exhibited good intra-day repeatability with the relative standard deviations (RSDs; %) of migration time and peak areas lying in the range of 0.3-1.2% and 0.5-4.2%, respectively. For inter-day reproducibility, the RSDs of the three OT capillary columns were found to be lying in the range of 0.3-5.5% and 0.3-4.5% for migration time and peak area, respectively. The RSDs of retention times for column-to-column for three batches of 10-LC, 15-LC and 20-LC OT capillary columns were in the range from 2.3% to 7.2%. Moreover, the fabricated 10-LC, 15-LC and 20-LC OT capillary columns exhibited good repeatability and stability for separation, which could be used successively for more than 120 runs with no observable changes on the separation efficiency. Copyright © 2017 Elsevier B.V. All rights reserved.

Physically incorporated extraction phase of solid-phase microextraction by sol-gel technology.

PubMed

Liu, Wenmin; Hu, Yuan; Zhao, Jinghong; Xu, Yuan; Guan, Yafeng

2006-01-13

A sol-gel method for the preparation of solid-phase microextraction (SPME) fiber was described and evaluated. The extraction phase of poly(dimethysiloxane) (PDMS) containing 3% vinyl group was physically incorporated into the sol-gel network without chemical bonding. The extraction phase itself is then partly crosslinked at 320 degrees C, forming an independent polymer network and can withstand desorption temperature of 290 degrees C. The headspace extraction of BTX by the fiber SPME was evaluated and the detection limit of o-xylene was down to 0.26 ng/l. Extraction and determination of organophosphorus pesticides (OPPs) in water, orange juice and red wine by the SPME-GC thermionic specified detector (TSD) was validated. Limits of detection of the method for OPPs were below 10 ng/l except methidathion. Relative standard deviations (RSDs) were in the range of 1-20% for pesticides being tested.

HPLC determination of guaifenesin with selected medications on underivatized silica with an aqueous-organic mobile phase.

PubMed

Wilcox, M L; Stewart, J T

2000-10-01

A high performance liquid chromatography procedure has been developed for the simultaneous determination of guaifenesin pseudoephedrine-dextromethorphan and guaifenesin-pseudoephedrine in commercially available capsule dosage forms and guaifenesin-codeine in a commercial cough syrup dosage form. The separation and quantitation are achieved on a 25-cm underivatized silica column using a mobile phase of 60:40%) v/v 6.25 mM phosphate buffer, pH 3.0 - acetonitrile at a flow rate of 1 ml min(-1) with detection of all analytes at 216 nm. The separation is achieved within 10 min for each drug mixture. The method showed linearity for the guaifenesin-pseudoephedrine-dextromethorphan mixture in the 50-200, 7.5-30 and 2.5-10, microg ml(-1) ranges, respectively. The intra- and inter-day RSDs ranged from 0.23 to 4.20%, 0.18 to 2.85%, and 0.13 to 5.04% for guaifenesin, pseudoephedrine, and dextromethorphan, respectively. The guaifenesin pseudoephedrine mixture yielded linear ranges of 25-100 and 3.75-15 microg ml(-1) and intra- and inter-day RSDs ranged from 0.65 to 4.18% and 0.23 to 3.00% for guaifenesin and pseudoephedrine, respectively. The method showed linearity for the guaifenesin-codeine mixture in the 25-100 and 2.5-10 microg ml(-1) ranges and RSDs ranged from 0.37 to 4.25% and 0.14 to 2.08% for guaifenesin and codeine, respectively.

Treatment of posttraumatic reflex sympathetic dystrophy syndrome (RSDS) with intravenous blocks of a mixture of corticosteroid and lidocaine: a retrospective review of 17 consecutive cases.

PubMed

Tountas, A A; Noguchi, A

1991-01-01

Seventeen consecutive patients with posttraumatic reflex sympathetic dystrophy syndrome (RSDS) were treated with one or more regional i.v. blocks of methylprednisolone sodium succinate and lidocaine HCL after physical therapy and oral medications had failed to produce satisfactory relief of their symptoms. In 12 of these patients the upper extremity was affected, and in five, it was the lower extremity. A fracture of the distal radius was the most frequent predisposing event. The average delay between injury and the manifestation of RSDS was 2.5 months (range 2 days to almost 6 months). The index treatment in all cases started within 3 months of the onset of symptoms. The number of i.v. blocks given ranged from one to four (average 2.4). The side effects and complications were negligible. The treatment, which in most cases was given exclusively on an outpatient basis, was well tolerated by all patients except one. Assessment of 16 of them at 6 months showed that 11 had total or almost total relief of their symptoms. When 15 of the patients were reassessed at an average follow-up of 28 months (range 12-48 months), it was noted that none of the patients with an early satisfactory response experienced recurrence of their symptoms. The condition of the symptomatic patients in the interim had improved overall. Analysis of the cases with an unsatisfactory outcome suggested that the primary reason for failure was inadequate treatment rather than ineffectiveness of the treatment used. It was concluded that this method is simple, safe, and well tolerated and should be regarded as a first choice for posttraumatic RSDS.

Separation and simultaneous determination of rutin, puerarin, daidzein, esculin and esculetin in medicinal preparations by non-aqueous capillary.

PubMed

Li, Cunhong; Chen, Anjia; Chen, Xiaofeng; Chen, Xingguo; Hu, Zhide

2005-09-01

A simple method for the simultaneous determination of five bioactive components (rutin, puerarin, daidzein esculin and esculetin) in traditional medicinal preparations by non-aqueous capillary electrophoresis with UV detection has been developed for the first time. A running buffer composed of 15% acetonitrile, 2.5% acetic acid and 90 mM sodium cholate in methanol was found to be the most suitable for this separation. The limits of detection for five analytes were over the range of 0.050-1.216 microg ml(-1). The relative standard deviations (R.S.Ds.) of the migration times and the peak areas of the analytes were in the range of 1.3-2.9% and 2.2-2.7% (intraday), 1.7-1.9% and 2.8-3.6% (interday), respectively. In the tested concentration range, linear relationships (correlation coefficients: 0.9974 for rutin, 0.9976 for puerarin, 0.9981 for daidzein, 0.9972 for esculin and 0.9929 for esculetin) between peak areas and concentrations of the analytes were obtained. This method has been successfully applied to simultaneous determination of the five bioactive components with recoveries over the range of 89.4-107.4%.

Amino modified multi-walled carbon nanotubes/polydimethylsiloxane coated stir bar sorptive extraction coupled to high performance liquid chromatography-ultraviolet detection for the determination of phenols in environmental samples.

PubMed

Hu, Cong; Chen, Beibei; He, Man; Hu, Bin

2013-07-26

In this work, amino modified multi-walled carbon nanotubes/polydimethylsiloxane (multi-walled carbon nanotubes-4,4'-diaminodiphenylmethane/polydimethylsiloxane, MWCNTs-DDM/PDMS) was synthesized, and utilized as a novel coating for stir bar sorptive extraction (SBSE) of seven phenols (phenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dimethylphenol, p-choro-m-cresol and 2,4,6-trichlorphenol) in environmental water and soil samples, followed by high performance liquid chromatography-ultraviolet detection (HPLC-UV). The prepared MWCNTs-DDM/PDMS coated stir bar was characterized and good preparation reproducibility was obtained with the relative standard deviations (RSDs) ranging from 4.7% to 11.3% (n=9) in one batch, and from 4.8% to 13.9% (n=8) among different batches. Several parameters affecting the extraction of seven target phenols by MWCNTs-DDM/PDMS-SBSE including extraction time, stirring rate, pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.14μg/L (2-nitrophenol) to 1.76μg/L (phenol) and the limits of quantification (LOQs, S/N=10) were found to be in the range of 0.46μg/L (2-nitrophenol) to 5.8μg/L (phenol). The linear range was 5-1000μg/L for phenol and 4-nitrophenol, 1-1000μg/L for 2-nitrophenol and 2-1000μg/L for other phenols, respectively. The RSDs of the developed method were in the range of 6.2-11.6% (n=8, c=10μg/L) and the enrichment factors were from 6.5 to 62.8-fold (theoretical enrichment factor was 100-fold). The proposed method was successfully applied to the analysis of phenols in environmental water and soil samples, and good recoveries were obtained for the spiked samples. The proposed method is simple, highly sensitive and suitable for the analysis of trace phenols in environmental samples with complex matrix. Copyright © 2013 Elsevier B.V. All rights reserved.

[Determination of bisphenol A from toys and food contact materials by derivatization and gas chromatography-mass spectrometry].

PubMed

Gao, Yonggang; Zhang, Yanyan; Gao, Jianguo; Zhang, Huiling; Zheng, Lisha; Chen, Jing

2012-10-01

A method was developed for the determination of bisphenol A (BPA) in toys and food contact materials. The BPA was extracted with Soxhlet extraction method from the sample and reacted with acetic anhydride. The final product was determined by gas chromatography-mass spectrometry (GC-MS). To achieve the optimum derivatization performance, the derivatization time and dosage of derivatization reagent etc. were investigated. Under the optimized experimental conditions, the final product was stable and the peak shape was good. The linearity of the derivative was good in the range of 0.05 to 50 mg/L with the correlation coefficient (r2) above 0.999. The recoveries ranged from 80% to 93% at the spiked levels of 0.05, 1.00, 10.00 mg/kg with the relative standard deviations (RSDs) less than 3.7%. The limit of detection (S/N = 3) was 10 microg/kg. The method is accurate and has high recovery. The method is suitable for the inspection of bisphenol A in toys and food contact materials.

[Simultaneous determination of 22 typical pharmaceuticals and personal care products in environmental water using ultra performance liquid chromatography- triple quadrupole mass spectrometry].

PubMed

Wu, Chunying; Gu, Feng; Bai, Lu; Lu, Wenlong

2015-08-01

An analytical method for simultaneous determination of 22 typical pharmaceuticals and personal care products (PPCPs) in environmental water samples was developed by ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS). An Oasis HLB solid phase extraction cartridge, methanol as washing solution, water containing 0. 1% formic acid-methanol (7:3, v/v) as the mobile phases were selected for sample pretreatment and chromatographic separation. Based on the optimized sample pretreatment procedures and separation condition, the target recoveries ranged from 73% to 125% in water with the relative standard deviations ( RSDs) from 8.8% to 17.5%, and the linear ranges were from 2 to 2 000 µg/L with correlation coefficients (R2) not less than 0.997. The method can be applied to simultaneous determination of the 22 typical PPCPs in environmental water samples because of its low detection limits and high recoveries. It can provide support and help for the related research on water environmental risk assessment and control of the micro-organic pollutants.

Multi-residue determination of 171 pesticides in cowpea using modified QuEChERS method with multi-walled carbon nanotubes as reversed-dispersive solid-phase extraction materials.

PubMed

Han, Yongtao; Song, Le; Zou, Nan; Chen, Ronghua; Qin, Yuhong; Pan, Canping

2016-09-15

A rapid and sensitive method for the determination of 171 pesticides in cowpea was developed using multi-walled carbon nanotubes (MWCNTs) as reversed-dispersive solid-phase (r-DSPE) extraction materials. The clean-up performance of MWCNTs was proved to be obviously superior to PSA and GCB. This method was validated on cowpea spiked at 0.01 and 0.1mgkg(-1) with five replicates. The mean recoveries for 169 pesticides ranged from 74% to 129% with relative standard deviations (RSDs) (n=5) lower than 16.4%, except diflufenican and quizalofop-ethyl. Good linearity for all pesticides was obtained with the calibration curve coefficients (R(2)) larger than 0.9970. The limit of detection (LODs) and limit of quantification (LOQs) for the 171 pesticides ranged from 0.001 to 0.003mgkg(-1) and from 0.002 to 0.009mgkg(-1), respectively. The method was demonstrated to be reliable and sensitive for the routine monitoring of the 171 pesticides in cowpea samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Residue behavior and dietary intake risk assessment of three fungicides in tomatoes (Lycopersicon esculentum Mill.) under greenhouse conditions.

PubMed

Zhu, Xiaodan; Jia, Chunhong; Duan, Lifang; Zhang, Wei; Yu, Pingzhong; He, Min; Chen, Li; Zhao, Ercheng

2016-11-01

The residue behavior and dietary intake risk of three fungicides (pyrimethanil, iprodione, kresoxim-methyl) in tomatoes (Lycopersicon esculentum Mill.) grown in greenhouse were investigated. A simple, rapid analytical method for the quantification of fungicide residues in tomatoes was developed using gas chromatography coupled with mass spectrum detection (GC-MSD). The fortified recoveries were ranged from 87% to 103% with relative standard deviations (RSDs) varied from 4.7% to 12.1%. The results indicated that the dissipation rate of the studied fungicides in tomatoes followed first order kinetics with half lives in the range of 8.6-11.5 days. The final residues of all the fungicides in tomatoes were varied from 0.241 to 0.944 mg/kg. The results of dietary intake assessment indicated that the dietary intake of the three fungicides from tomatoes consumption for Chinese consumers were acceptable. This study would provide more understanding of residue behavior and dietary intake risk by these fungicides used under greenhouse conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

Salting-out assisted liquid-liquid extraction coupled to ultra-high performance liquid chromatography-tandem mass spectrometry for the determination of tetracycline residues in infant foods.

PubMed

Moreno-González, David; García-Campaña, Ana M

2017-04-15

The use of salting-out assisted liquid-liquid extraction (SALLE) combined with ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) has been evaluated for the determination of tetracyclines in infant foods based on meat and vegetables or in milk. To obtain satisfactory extraction efficiencies for the studied analytes, several parameters affecting the SALLE procedure were optimized. Analytical performances of the method were satisfactory, obtaining limits of quantification lower than 0.48μgkg -1 in all cases. The precision, expressed as relative standard deviation (%, RSD) was below 11.3%. The extraction efficiency for fortified samples ranged from 89.2 to 96.8%, with RSDs lower than 7.3%. Matrix effect was evaluated for all samples studied, being lower than |21|% in all cases. In relation to the low solvent consumption, the proposed methodology could be considered rapid, cheap and environmentally friendly. Its applicability has been successfully tested in a wide range of infant foods. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Rapid screening of acidity regulators in dairy by ion chromatography-high resolution mass spectrometry].

PubMed

Yun, Huan; Liu, Xin; Cui, Jie; Yang, Jing; Liu, Ying

2017-08-08

A method for screening of acidity regulators in dairy based on ion chromatography-high resolution mass spectrometry technology (IC-HRMS) was set up. The dairy samples were extracted by KOH (pH 7-8) and Oasis MAX SPE column, and separated by a Dionex IonPac AS11-HC column (250 mm×4 mm). All the acidity regulators were detected by Orbitrap full scan mode. Taking six organic acids as an example, the calibration curves showed good linearities in the range of 0.05-5.00 mg/L, and the correlation coefficients ( r ) were higher than 0.99. By detecting the spiked samples, the recoveries were in the range of 74.3%-115.5% with the relative standard deviations (RSDs) between 0.64% and 4.81%. Malic acid, citric acid, lactic acid, succinic acid and adipic acid could be detected by IC-HRMS in the commercial dairy samples. The results indicate that the method is simple, rapid and suitable for the qualitative screening of acidity regulators in dairy products.

[Simultaneous determination of nine preservatives in fruits using gas chromatography-mass spectrometry].

PubMed

Peng, Shunü; Wang, Qiuquan; Fang, Lanlan; Guo, Shanyong; Zeng, Zhouhua; Lin, Zhuguang

2014-01-01

A gas chromatography-mass spectrometry (GC-MS) method was established for the simultaneous determination of nine typical preservatives (pyrimethanil, chlorothalonil, chlorpyrifos, triadimefon, thiabendazole, imazalil, myclobutanil, iprodione, prochloraz) in fruits. The fruit samples were subjected to ultrasonic extraction with hexane/ethyl acetate (1/1, v/v), and followed by purification using diatomite column chromatography with hexane/ethyl acetate (1/3, v/v) eluant. Qualitative and quantitative analysis of the nine preservatives were performed on the GC-MS at full-scan (SCAN) and selected ion monitoring (SIM) modes, in which triphenylphosphate was used as the internal standard. The detection limits obtained for the nine preservatives were ranged from 0.10 microg/kg to 2.16 microg/kg. The average recoveries were in the range of 75.3% to 128% at the spiked levels of 50, 100 and 200 microg/kg with the relative standard deviations (RSDs) of 1.57% to 11.6% (n = 5). The results showed that the developed method is sensitive and accurate for the determination of the nine preservatives in fruits.

[Determination of penicillin intermediate and three penicillins in milk by high performance capillary electrophoresis].

PubMed

Tian, Chunqiu; Tan, Huarong; Gao, Liping; Shen, Huqin; Qi, Kezong

2011-11-01

A high performance capillary electrophoresis (HPCE) method was developed for the simultaneous determination of penicillin intermediate and penicillins in milk, including 6-amino-penicillanic acid (6-APA), penicillin G (PEN), ampicillin (AMP) and amoxicillin (AMO). The main parameters including the ion concentration and pH value of running buffer, separation voltage and column temperature were optimized systematically by orthogonal test. The four penicillins (PENs) were baseline separated within 4.5 min with the running buffer of 40 mmol/L potassium dihydrogen phosphate-20 mmol/L borax solution (pH 7.8), separation voltage of 28 kV and column temperature of 30 degrees C. The calibration curves showed good linearity in the range of 1.56 - 100 mg/L, and the correlation coefficients (r2) were between 0.9979 and 0.9998. The average recoveries at three spiked levels were in the range of 84.91% - 96.72% with acceptable relative standard deviations (RSDs) of 1.11% - 9.11%. The method is simple, fast, accurate and suitable for the determination of penicillins in real samples.

Optimisation of ultrasound-assisted reverse micelles dispersive liquid-liquid micro-extraction by Box-Behnken design for determination of acetoin in butter followed by high performance liquid chromatography.

PubMed

Roosta, Mostafa; Ghaedi, Mehrorang; Daneshfar, Ali

2014-10-15

A novel approach, ultrasound-assisted reverse micelles dispersive liquid-liquid microextraction (USA-RM-DLLME) followed by high performance liquid chromatography (HPLC) was developed for selective determination of acetoin in butter. The melted butter sample was diluted and homogenised by n-hexane and Triton X-100, respectively. Subsequently, 400μL of distilled water was added and the microextraction was accelerated by 4min sonication. After 8.5min of centrifugation, sedimented phase (surfactant-rich phase) was withdrawn by microsyringe and injected into the HPLC system for analysis. The influence of effective variables was optimised using Box-Behnken design (BBD) combined with desirability function (DF). Under optimised experimental conditions, the calibration graph was linear over the range of 0.6-200mgL(-1). The detection limit of method was 0.2mgL(-1) and coefficient of determination was 0.9992. The relative standard deviations (RSDs) were less than 5% (n=5) while the recoveries were in the range of 93.9-107.8%. Copyright © 2014. Published by Elsevier Ltd.

Exploring rippled scour depressions offshore Huntington Beach, CA

USGS Publications Warehouse

Phillips, Eleyne L.; Storlazzi, Curt D.; Dartnell, Peter; Edwards, Brian D.

2007-01-01

U.S. Geological Survey (USGS) scientists used 1999 multibeam data, and 2002 lidar data collected on the inner shelf off southern California to investigate a field of (<1 m) features, termed "Rippled Scour Depressions" (RSDs). RSDs are elongate, shore-normal, and bathymetrically depressed features; their morphology was determined from multibeam and lidar bathymetry. Wavelengths of ripples seen within RSDs and on the surrounding seafloor were calculated from photography and video collected in 2004 and related to sediment samples collected in the same year. The RSDs were divided into two areas: Region I RSDs contained large (∼80 cm wavelength), straight-crested ripples with coarse-grained lag, and decreased in area between 1999 and 2002; Region II RSDs were smaller, in shallower water, closer to shore, and contained shorter (∼30 cm wavelength) ripples, and increased in area from 1999–2002. The RSDs did not display marked alongshore asymmetry.

Determination of parabens in human milk and other food samples by capillary electrophoresis after dispersive liquid-liquid microextraction with back-extraction.

PubMed

Alshana, Usama; Ertaş, Nusret; Göğer, Nilgün G

2015-08-15

Dispersive liquid-liquid microextraction (DLLME) with back-extraction was used prior to capillary electrophoresis (CE) for the extraction of four parabens. Optimum extraction conditions were: 200 μL chloroform (extraction solvent), 1.0 mL acetonitrile (disperser solvent) and 1 min extraction time. Back-extraction of parabens from chloroform into a 50mM sodium hydroxide solution within 10s facilitated their direct injection into CE. The analytes were separated at 12°C and 25 kV with a background electrolyte of 25 mM borate buffer containing 5.0% (v/v) acetonitrile. Enrichment factors were in the range of 4.3-10.7 and limits of detection ranged from 0.1 to 0.2 μg mL(-1). Calibration graphs showed good linearity with coefficients of determination (R(2)) higher than 0.9957 and relative standard deviations (%RSDs) lower than 3.5%. DLLME-CE was demonstrated to be a simple and rapid method for the determination of parabens in human milk and food with relative recoveries in the range of 86.7-103.3%. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fast Simultaneous Determination of 13 Nucleosides and Nucleobases in Cordyceps sinensis by UHPLC-ESI-MS/MS.

PubMed

Zong, Shi-Yu; Han, Han; Wang, Bing; Li, Ning; Dong, Tina Ting-Xia; Zhang, Tong; Tsim, Karl W K

2015-12-04

A reliable ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS) method for the fast simultaneous determination of 13 nucleosides and nucleobases in Cordyceps sinensis (C. sinensis) with 2-chloroadenosine as internal standard was developed and validated. Samples were ultrasonically extracted in an ice bath thrice, and the optimum analyte separation was performed on an ACQUITY UPLC(TM) HSS C18 column (100 mm × 2.1 mm, 1.8 μm) with gradient elution. All targeted analytes were separated in 5.5 min. Furthermore, all calibration curves showed good linear regression (r > 0.9970) within the test ranges, and the limits of quantitation and detection of the 13 analytes were less than 150 and 75 ng/mL, respectively. The relative standard deviations (RSDs) of intra- and inter-day precisions were <6.23%. Recoveries of the quantified analytes ranged within 85.3%-117.3%, with RSD < 6.18%. The developed UHPLC-ESI-MS/MS method was successfully applied to determine nucleosides and nucleobases in 11 batches of C. sinensis samples from different regions in China. The range for the total content in the analyzed samples was 1329-2057 µg/g.

Rapid gas chromatography with flame photometric detection of multiple organophosphorus pesticides in Salvia miltiorrhizae after ultrasonication assisted one-step extraction.

PubMed

Zhang, Shanshan; Liu, Xiaofei; Qin, Jia'an; Yang, Meihua; Zhao, Hongzheng; Wang, Yong; Guo, Weiying; Ma, Zhijie; Kong, Weijun

2017-11-15

A simple and rapid gas chromatography-flame photometric detection (GC-FPD) method was developed for the determination of 12 organophosphorus pesticides (OPPs) in Salvia miltiorrhizae by using ultrasonication assisted one-step extraction (USAE) without any clean-up steps. Some crucial parameters such as type of extraction solvent were optimized to improve the method performance for trace analysis. Any clean-up steps were negligent as no interferences were detected in the GC-FPD chromatograms for sensitive detection. Under the optimized conditions, limits of detection (LODs) and quantitation (LOQs) for all pesticides were in the range of 0.001-0.002mg/kg and 0.002-0.01mg/kg and 0.002-0.01mg/kg, respectively, which were all below the regulatory maximum residue limits suggested. RSDs for method precision (intra- and inter-day variations) were lower than 6.8% in approval with international regulations. Average recovery rates for all pesticides at three fortification levels (0.5, 1.0 and 5.0mg/kg) were in the range of 71.2-101.0% with relative standard deviations (RSDs) <13%. The developed method was evaluated for its feasibility in the simultaneous pre-concentration and determination of 12 OPPs in 32 batches of real S. miltiorrhizae samples. Only one pesticide (dimethoate) out of the 12 targets was simultaneously detected in four samples at concentrations of 0.016-0.02mg/kg. Dichlorvos and omethoate were found in the same sample from Sichuan province at 0.004 and 0.027mg/kg, respectively. Malathion and monocrotophos were determined in the other two samples at 0.014 and 0.028mg/kg, respectively. All the positive samples were confirmed by LC-MS/MS. The simple, reliable and rapid USAE-GC-FPD method with many advantages over traditional techniques would be preferred for trace analysis of multiple pesticides in more complex matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

Development and validation of a solid-phase extraction method coupled with HPLC-UV detection for the determination of biogenic amines in Chinese rice wine.

PubMed

Zhang, Ying; Li, Yan; Zhu, Xiao-Juan; Li, Min; Chen, Hao-Yu; Lv, Xiao-Ling; Zhang, Jian

2017-07-01

A reliable and accurate method for the determination of seven biogenic amines (BAs) was developed and validated with Chinese rice wine samples. The BAs were derivatised with dansyl chloride, cleaned up using solid-phase extraction (SPE) and separated by high-performance liquid chromatography (HPLC) coupled with ultraviolet (UV) detection. The optimised derivatisation reaction, conducted at pH 9.6 and 60°C for 30 min, ensured baseline separation and peak symmetry for each BA. SPE clean-up using Oasis MCX cartridges yielded good recovery rates for all BAs and effectively reduced matrix effects. The developed method shows good linearity with determination coefficients of more than 0.9989 over a concentration range of 0.1-100 mg l -1 . The limits of detection (LODs) for the investigated BAs ranged from 2.07 to 5.56 µg l -1 . The intra- and inter-day relative standard deviations (RSDs) ranged from 0.86% to 3.81% and from 2.13% to 3.82%, respectively. Spiking experiments showed that the overall recovery rates ranged from 85% to 113%. Thus, the proposed method was demonstrated as being suitable for simultaneous detection, with accurate and precise quantification, of BAs in Chinese rice wine.

[Determination of capsaicinoids and eugenol in waste-edible-oil by liquid-liquid extraction and liquid chromatography-tandem mass spectrometry].

PubMed

Zhang, Zhong; Ren, Fei; Zhang, Pan

2012-11-01

A method was developed for the determination of capsaicinoids (capsaicin, dihydrocapsaicin and synthetic capsaicin) and eugenol in waste-edible-oil extracted by liquid-liquid extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The capsaicinoids and eugenol in waste-edible-oil were extracted by methanol, and then separated by a SUPEL COSIL ABZ + Plus dC18 column (150 mm x4.6 mm, 5 microm). The analysis was performed by MS/MS with electrospray ionization in positive and negative ion modes with multiple reaction monitoring (MRM). The limits of detection for capsaicin, dihydrocapsaicin, synthetic capsaicin and eugenol were 0.02, 0.03, 0.03 and 0.6 microg/L, respectively. The good linear relationships were obtained in certain concentration ranges of capsaicinoids and eugenol. The relative standard deviations (RSDs, n=5) of same-worker and different-worker were less than 5%. The method is exclusive, sensitive and accurate, and can be used in waste-edible-oil determination.

Ultrasonication extraction and gel permeation chromatography clean-up for the determination of polycyclic aromatic hydrocarbons in edible oil by an isotope dilution gas chromatography–mass spectrometry.

PubMed

Wang, Jian-Hua; Guo, Cui

2010-07-09

An analytical method for the determination of US EPA priority pollutant 16 polycyclic aromatic hydrocarbons (PAHs) in edible oil was developed by an isotope dilution gas chromatography-mass spectrometry (GC-MS). Extraction was performed with ultrasonication mode using acetonitrile as solvent, and subsequent clean-up was applied using narrow gel permeation chromatographic column. Three deuterated PAHs surrogate standards were used as internal standards for quantification and analytical quality control. The limits of quantification (LOQs) were globally below 0.5 ng/g, the recoveries were in the range of 81-96%, and the relative standard deviations (RSDs) were lower than 20%. Further trueness assessment of the method was also verified through participation in international cocoa butter proficiency test (T0638) organised by the FAPAS with excellent results in 2008. The results obtained with the described method were satisfying (z ≤ 2). The method has been applied to determine PAH in real edible oil samples.

A nanocomposite consisting of silica-coated magnetite and phenyl-functionalized graphene oxide for extraction of polycyclic aromatic hydrocarbon from aqueous matrices.

PubMed

Mahpishanian, Shokouh; Sereshti, Hassan; Ahmadvand, Mohammad

2017-05-01

In this study, graphene oxide was covalently immobilized on silica-coated magnetite and then modified with 2-phenylethylamine to give a nanocomposite of type Fe 3 O 4 @SiO 2 @GO-PEA that can be applied to the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples. The resulting microspheres (Fe 3 O 4 @SiO 2 @GO-PEA) were characterized by Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), CHNS elemental analysis, and vibrating sample magnetometry (VSM) techniques. The adsorbent possesses the magnetic properties of Fe 3 O 4 nanoparticles that allow them easily to be separated by an external magnetic field. They also have the high specific surface area of graphene oxide which improves adsorption capacity. Desorption conditions, extraction time, amount of adsorbent, salt concentration, and pH were investigated and optimized. Following desorption, the PAHs were quantified by gas chromatography with flame ionization detection (GC-FID). The limits of detection (at an S/N ratio of 3) were achieved from 0.005 to 0.1μg/L with regression coefficients (R 2 ) higher than 0.9954. The relative standard deviations (RSDs) were below 5.8% (intraday) and 6.2% (inter-day), respectively. The method was successfully applied to the analysis of PAHs in environmental water samples where it showed recoveries in the range between 71.7% and 106.7% (with RSDs of 1.6% to 8.4%, for n=3). The results indicated that the Fe 3 O 4 @SiO 2 @GO-PEA microspheres had a great promise to extraction of PAHs from different water samples. Copyright © 2016. Published by Elsevier B.V.

Polydimethylsiloxane/metal-organic frameworks coated stir bar sorptive extraction coupled to gas chromatography-flame photometric detection for the determination of organophosphorus pesticides in environmental water samples.

PubMed

Xiao, Zuowei; He, Man; Chen, Beibei; Hu, Bin

2016-08-15

In this work, the metal-organic frameworks (MOFs), MIL-101-Cr-NH2 was synthesized via a direct hydrothermal method, and a polydimethylsiloxane (PDMS)/MIL-101-Cr-NH2 coated stir bar was prepared by sol-gel technique. Good reproducibility was obtained for the preparation of PDMS/MIL-101-Cr-NH2 coated stir bar with the relative standard deviations (RSDs) ranging from 3.7 to 5.2% (n=7) in one batch, and from 5.4 to 9.2% (n=7) among different batches. With the high surface area and rich benzene ring structure of MIL-101-Cr-NH2, the prepared PDMS/MIL-101-Cr-NH2 coated stir bar presented higher extraction efficiency for target organophosphorus pesticides (OPPs, including phorate, diazinon, malathion, fenthion, quinalphos and ethion) over PDMS coated stir bar. Based on it, a new method of PDMS/MIL-101-Cr-NH2 coated stir bar sorptive extraction (SBSE) coupled to gas chromatography-flame photometric detection (GC-FPD) was proposed for the determination of six OPPs in environmental water samples. The operation parameters affecting the extraction efficiency of SBSE, including extraction time, stirring rate, desorption time and ionic strength, were investigated. Under the optimal conditions, the limits of detection (S/N=3) were found to be in the range of 0.043-0.085μgL(-1) for the six target OPPs, and the linear range was 0.5-100μgL(-1) for malathion and 0.2-100μgL(-1) for other five OPPs. The RSDs of the proposed method evaluated at 1µgL(-1) for each OPP were in the range of 5.9-8.7% (intra-day, n=7) and 6.1-10.7% (inter-day, n=5), respectively. The enrichment factors were varied from 110 to 151-fold (theoretical enrichment factor was 200-fold). The proposed method was applied to the analysis of OPPs in East Lake and pond water samples with recoveries in the range of 89.3-115% and 80.0-113% for the spiked East Lake and pond water samples, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Magnetic solid phase extraction and gas chromatography-mass spectrometrical analysis of sixteen polycyclic aromatic hydrocarbons.

PubMed

Cai, Ying; Yan, Zhihong; NguyenVan, Manh; Wang, Lijia; Cai, Qingyun

2015-08-07

Fluorenyl functionalized superparamagnetic core/shell magnetic nanoparticles (MNPs, Fe3O4@SiO2@Flu) were prepared and characterized by transmission electron microscope, X-ray diffraction and infrared spectroscopy. The MNPs having an average diameter of 200nm were then used as solid-phase extraction sorbent for the determination of 16 priority pollutants polycyclic aromatic hydrocarbons (PAHs) in water samples designated by United States Environmental Protection Agency (U.S. EPA). The main influencing parameters, including sorbent amount, desorption solvent, sample volume and extraction time were optimized. Analyses were performed on gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring (SIM) mode. Method validation proved the feasibility of the developed sorbents for the quantitation of the investigated analytes at trace levels. Limit of detection ranging from 0.5 to 4.0ng/L were obtained. The repeatability was investigated by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) lower than 13.1%. Finally, the proposed method was successfully applied for the determination of PAHs in water samples with the recoveries in the range of 96.0-106.7%. Copyright © 2015 Elsevier B.V. All rights reserved.

Non-aqueous capillary electrophoresis for separation and simultaneous determination of fraxin, esculin and esculetin in Cortex fraxini and its medicinal preparations.

PubMed

Li, Cunhong; Chen, Anjia; Chen, Xiaofeng; Ma, Xiao; Chen, Xingguo; Hu, Zhide

2005-11-01

A non-aqueous capillary electrophoresis method has been developed for the separation and simultaneous determination of fraxin, esculin and esculetin in Cortex fraxini and its preparation for the first time. Optimum separation of the analytes was obtained on a 47 cm x 75 microm i.d. fused-silica capillary using a non-aqueous buffer system of 60 mM sodium cholate, 20 mM ammonium acetate, 20% acetonitrile and 3% acetic acid at 20 kV and 292 K, respectively. The relative standard deviations (RSDs) of the migration times and the peak heights of the three analytes were in the range of 0.23-0.28 and 2.12-2.60%, respectively. Detection limits of fraxin, esculin and esculetin were 0.1557, 0.4073 and 0.5382 microg/mL, respectively. In the tested concentration range, good linear relationships (correlation coefficients 0.9995 for fraxin, 0.9999 for esculin and 0.9992 for esculetin) between peak heights and concentrations of the analytes were observed. This method has been successfully applied to simultaneous determination of the three bioactive components with the recoveries from 90.2 to 109.2% in the five samples.

A novel sorptive extraction method based on polydimethylsiloxane frit for determination of lung cancer biomarkers in human serum.

PubMed

Xu, Hui; Wang, Shuyu

2012-04-29

In this study, a porous polypropylene frit was coated with polydimethylsiloxane (PDMS) as extraction medium, based on the home-made PDMS-frit, a rapid, simple and sensitive sorptive extraction method was established for analysis of potential biomarkers of lung cancer (hexanal and heptanal) in human serum samples. In the method, derivatization and extraction occurred simultaneously on the PDMS-frit, then the loaded frit was ultrasonically desorbed in acetonitrile. Polymerization, derivatization-extraction and desorption conditions were optimized. Under the optimal conditions, satisfactory results were gained, a wide linear application range was obtained in the range of 0.002-5.0 μmol L(-1) (R>0.997) for two aldehydes, the detection limits (SN(-1)=3) were 0.5 nmol L(-1) for hexanal and 0.4 nmol L(-1) for heptanal. The relative standard deviations (RSDs, n=5) of the method were below 7.9% and the recoveries were above 72.7% for the spiked serum. All these results hint that the proposed method is potential for disease markers analysis in complex biological samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of Pyrethroids in Tea Brew by GC-MS Combined with SPME with Multiwalled Carbon Nanotube Coated Fiber.

PubMed

Ren, Dongxia; Sun, Chengjun; Ma, Guanqun; Yang, Danni; Zhou, Chen; Xie, Jiayu; Li, Yongxin

2018-01-01

A new method has been developed to simultaneously determine 7 pyrethroid residues in tea brew using gas chromatography-mass spectrometry (GC-MS) combined with solid phase microextraction (SPME) with multiwalled carbon nanotubes (MWCNTs) coated fiber. The MWCNTs coated fiber of SPME was homemade by using stainless steel wire as coating carrier and polyacrylonitrile (PAN) solution as adhesive glue. Under the optimized conditions, a good linearity was shown for bifenthrin, fenpropathrin, permethrin, and cyfluthrin in 1-50 ng mL -1 and for cypermethrin, fenvalerate, and deltamethrin in 5-50 ng mL -1 . The correlation coefficients were in the range of 0.9948-0.9999. The average recoveries of 7 pyrethroids were 94.2%-107.3% and the relative standard deviations (RSDs) were less than 15%. The detection limit of the method ranged from 0.12 to 1.65 ng mL -1 . The tea brew samples made from some commercial tea samples were analyzed. Among them, bifenthrin, fenpropathrin, and permethrin were found. The results show that the method is rapid and sensitive and requires low organic reagent consumption, which can be well used for the detection of the pyrethroids in tea brew.

Dissipation of Flonicamid in Honeysuckle and Its Transfer during Brewing Process.

PubMed

Wang, Yujie; Xue, Jian; Jin, Hongyu; Ma, Shuangcheng

2017-05-01

The dissipation of flonicamid in Honeysuckle and transfer pattern from Honeysuckle to its tea infusion were investigated. Flonicamid was applied on Honeysuckle crop at two dosages, 60 g of active gradient per hectare (g a.i. hm -2 ) and 180 g a.i. hm -2 (recommended and triple the recommended) in Fenqiu, Henan Province in 2015 and 2016. Gas Chromatography-Electron Capture Detector (GC-ECD) detection methods were developed for the analysis of flonicamid residues in honeysuckles and its infusion. The recoveries in both honeysuckles and its infusion ranged from 81.5 to 101.7% with relative standard deviations (RSDs) of 3.2-9.1%. The dissipations of flonicamid in Honeysuckle were found to follow the first order kinetics with half-life ranging between 2.8 and 3.2 d. After recommended dose pesticide application, contents of flonicamid residues were lower than theoretical maximum residue limit (tMRL). Flonicamid residues can easily transfer from Honeysuckle to its tea infusion and transfer rates of flonicamid decrease with the brewing temperature reduction or the brewing times increase. These results are helpful to establish maximum residue limit and develop guidance on the appropriate and secure use of flonicamid in Honeysuckle.

Methyl angolensate changes in Khaya ivorensis after fungal infection.

PubMed

Reche, Karine V G; de Souza, Gezimar D; Trapp, Marília A; Rodrigues-Filho, Edson; Silva, Sebastião C; Fernandes, João B; Vieira, Paulo C; Muller, Manfred W; da Silva, M Fátima das G F

2009-12-01

Khaya ivorensis with and without symptoms of stem and branch cankers, caused by Botryosphaeria rhodina were examined in order to determine whether the secondary metabolites in this plant were associated with a chemical defense response. This study provides evidence that the limonoid methyl angolensate (MA) is present at higher concentrations in K. ivorensis with symptoms of stem cankers rather than in the plants without symptoms. A rapid, sensitive and selective HPLC-ESI-MS/MS method (using selected reaction monitoring--SRM--mode) was developed for quantification of MA in all aerials parts of such plants, with a good linearity over a range of 0.1-20.0 g/kg, with r(2)>0.996+/-6.1%. The limits of detection (LOD) and quantification (LOQ) were less than 0.03 g/kg and 0.08 g/kg, respectively. Relative Standard Deviations (RSDs) ranged from 1.7% to 19.2% for all matrices. While the MA concentration did not change in the stem bark, its amounts increased nearly fourfold in stems and by 20% in leaves, when plants with symptoms were compared with those without symptoms. These data suggest that MA plays a role in plant-pathogen interactions, probably as a phytoanticipin.

Development of electrochemiluminescent inhibition method for determination of gentian violet in aquatic water.

PubMed

Wang, Sui; Hao, Tingting; Yu, Xinwei; Gai, Panpan; Guo, Zhiyong

2012-04-01

Gentian violet (GV) was found to quench the electrochemiluminescence (ECL) of the tris(2,2'-bipyridyl)ruthenium(II)/tris-n-propylamine (Ru(bpy)3(2+)-TPA) system at a glass carbon electrode (GCE). Based on the ECL signal changes, a simple and ultrasensitive detection method for GV in aquatic water was established. Under the optimized conditions, the quenched ECL intensity versus the logarithm of the concentration of GV was linear over a concentration range from 1.0×10(-10) to 5.0×10(-7) mol L(-1), and the limit of detection (LOD) was found to be 4.5×10(-12) mol L(-1) (S/N=3). The results obtained by the ECL system were better than other reported methods in literatures in terms of sensitivity or linear response range. The method was successfully applied to determine GV in aquatic water, and the relative standard deviations (RSDs) were found less than 6.3%, and the recoveries were obtained from 98.7 to 111.0%. Moreover, a possible mechanism of the quenching effect was primarily discussed based on UV-visible absorption spectra, cyclic voltammograms and IECL-E curves. Copyright © 2011 Elsevier B.V. All rights reserved.

Validation of PCR methods for quantitation of genetically modified plants in food.

PubMed

Hübner, P; Waiblinger, H U; Pietsch, K; Brodmann, P

2001-01-01

For enforcement of the recently introduced labeling threshold for genetically modified organisms (GMOs) in food ingredients, quantitative detection methods such as quantitative competitive (QC-PCR) and real-time PCR are applied by official food control laboratories. The experiences of 3 European food control laboratories in validating such methods were compared to describe realistic performance characteristics of quantitative PCR detection methods. The limit of quantitation (LOQ) of GMO-specific, real-time PCR was experimentally determined to reach 30-50 target molecules, which is close to theoretical prediction. Starting PCR with 200 ng genomic plant DNA, the LOQ depends primarily on the genome size of the target plant and ranges from 0.02% for rice to 0.7% for wheat. The precision of quantitative PCR detection methods, expressed as relative standard deviation (RSD), varied from 10 to 30%. Using Bt176 corn containing test samples and applying Bt176 specific QC-PCR, mean values deviated from true values by -7to 18%, with an average of 2+/-10%. Ruggedness of real-time PCR detection methods was assessed in an interlaboratory study analyzing commercial, homogeneous food samples. Roundup Ready soybean DNA contents were determined in the range of 0.3 to 36%, relative to soybean DNA, with RSDs of about 25%. Taking the precision of quantitative PCR detection methods into account, suitable sample plans and sample sizes for GMO analysis are suggested. Because quantitative GMO detection methods measure GMO contents of samples in relation to reference material (calibrants), high priority must be given to international agreements and standardization on certified reference materials.

Determination of imidazole derivatives by micellar electrokinetic chromatography combined with solid-phase microextraction using activated carbon-polymer monolith as adsorbent.

PubMed

Shih, Yung-Han; Lirio, Stephen; Li, Chih-Keng; Liu, Wan-Ling; Huang, Hsi-Ya

2016-01-08

In this study, an effective method for the separation of imidazole derivatives 2-methylimidazole (2-MEI), 4- methylimidazole (4-MEI) and 2-acetyl-4-tetrahydroxybutylimidazole (THI) in caramel colors using cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography (CSEI-sweeping-MEKC) was developed. The limits of detection (LOD) and quantitation (LOQ) for the CSEI-sweeping-MEKC method were in the range of 4.3-80μgL(-1) and 14-270μgL(-1), respectively. Meanwhile, a rapid fabrication activated carbon-polymer (AC-polymer) monolithic column as adsorbent for solid-phase microextraction (SPME) of imidazole colors was developed. Under the optimized SPME condition, the extraction recoveries for intra-day, inter-day and column-to-column were in the range of 84.5-95.1% (<6.3% RSDs), 85.6-96.1% (<4.9% RSDs), and 81.3-96.1% (<7.1% RSDs), respectively. The LODs and LOQs of AC-polymer monolithic column combined with CSEI-sweeping-MEKC method were in the range of 33.4-60.4μgL(-1) and 111.7-201.2μgL(-1), respectively. The use of AC-polymer as SPME adsorbent demonstrated the reduction of matrix effect in food samples such as soft drink and alcoholic beverage thereby benefiting successful determination of trace-level caramel colors residues using CSEI-sweeping-MEKC method. The developed AC-polymer monolithic column can be reused for more than 30 times without any significant loss in the extraction recovery for imidazole derivatives. Copyright © 2015 Elsevier B.V. All rights reserved.

Validation of an Analytical Method for Determination of 13 priority polycyclic aromatic hydrocarbons in mineral water using dispersive liquid-liquid microextraction and GC-MS

PubMed Central

Sadeghi, Ramezan; Kobarfard, Farzad; Yazdanpanah, Hassan; Eslamizad, Samira; Bayat, Mitra

2016-01-01

Dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography–mass spectrometry (GC–MS) was used for the extraction and determination of 13 polycyclic aromatic hydrocarbons (PAHs) in mineral water samples. In this procedure, the suitable combination of extraction solvent (500 µL chloroform) and disperser solvent (1000 µL acetone) were quickly injected into the water sample (10.00 mL) by Hamilton syringe. After centrifugation, 500 µL of the lower organic phase was dried under a gentle stream of nitrogen, re-dissolved in chloroform and injected into GC-MS. Chloroform and acetone were found to be the best extraction and disperser solvent, respectively. Validation of the method was performed using spiked calibration curves. The enrichment factor ranged from 93 to 129 and the recovery ranged from 71 to 90%. The linear ranges for all the PAHs were 0.10-2.80 ngmL-1. The relative standard deviations (RSDs) of PAHs in water by using anthracene-d10 as internal standard, were in the range of 4-11% for most of the analytes (n = 3). Limit of detection (LOD) for different PAHs were between 0.03 and 0.1 ngmL-1. The method was successfully applied for the analysis of PAHs in mineral water samples collected from Tehran. PMID:27610156

Determination of organophosphorus pesticides and their major degradation product residues in food samples by HPLC-UV.

PubMed

Peng, Guilong; He, Qiang; Lu, Ying; Mmereki, Daniel; Zhong, Zhihui

2016-10-01

A simple method based on dispersive solid-phase extraction (DSPE) and dispersive liquid-liquid microextraction method based on solidification of floating organic droplets (DLLME-SFO) was developed for the extraction of chlorpyrifos (CP), chlorpyrifos-methyl (CPM), and their main degradation product 3,5,6-trichloro-2-pyridinol (TCP) in tomato and cucumber samples. The determination was carried out by high performance liquid chromatography with ultraviolet detection (HPLC-UV). In the DSPE-DLLME-SFO, the analytes were first extracted with acetone. The clean-up of the extract by DSPE was carried out by directly adding activated carbon sorbent into the extract solution, followed by shaking and filtration. Under the optimum conditions, the proposed method was sensitive and showed a good linearity within a range of 2-500 ng/g, with the correlation coefficients (r) varying from 0.9991 to 0.9996. The enrichment factors ranged from 127 to 138. The limit of detections (LODs) were in the range of 0.12-0.68 ng/g, and the relative standard deviations (RSDs) for 50 ng/g of each analytes in tomato samples were in the range of 3.25-6.26 % (n = 5). The proposed method was successfully applied for the extraction and determination of the mentioned analytes residues in tomato and cucumber samples, and satisfactory results were obtained.

An interlaboratory comparison of sizing and counting of subvisible particles mimicking protein aggregates.

PubMed

Ripple, Dean C; Montgomery, Christopher B; Hu, Zhishang

2015-02-01

Accurate counting and sizing of protein particles has been limited by discrepancies of counts obtained by different methods. To understand the bias and repeatability of techniques in common use in the biopharmaceutical community, the National Institute of Standards and Technology has conducted an interlaboratory comparison for sizing and counting subvisible particles from 1 to 25 μm. Twenty-three laboratories from industry, government, and academic institutions participated. The circulated samples consisted of a polydisperse suspension of abraded ethylene tetrafluoroethylene particles, which closely mimic the optical contrast and morphology of protein particles. For restricted data sets, agreement between data sets was reasonably good: relative standard deviations (RSDs) of approximately 25% for light obscuration counts with lower diameter limits from 1 to 5 μm, and approximately 30% for flow imaging with specified manufacturer and instrument setting. RSDs of the reported counts for unrestricted data sets were approximately 50% for both light obscuration and flow imaging. Differences between instrument manufacturers were not statistically significant for light obscuration but were significant for flow imaging. We also report a method for accounting for differences in the reported diameter for flow imaging and electrical sensing zone techniques; the method worked well for diameters greater than 15 μm. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Simple and Rapid Immobilization of Coating Polymers on Poly(dimethyl siloxane)-glass Hybrid Microchips by a Vacuum-drying Method.

PubMed

Kitagawa, Fumihiko; Nakagawara, Syo; Nukatsuka, Isoshi; Hori, Yusuke; Sueyoshi, Kenji; Otsuka, Koji

2015-01-01

A simple and rapid vacuum-drying modification method was applied to several neutral and charged polymers to obtain coating layers for controlling electroosmotic flow (EOF) and suppressing sample adsorption on poly(dimethyl siloxane) (PDMS)-glass hybrid microchips. In the vacuum-dried poly(vinylpyrrolidone) coating, the electroosmotic mobility (μeo) was suppressed from +2.1 to +0.88 × 10(-4) cm(2)/V·s, and the relative standard deviation (RSD) of μeo was improved from 10.2 to 2.5% relative to the bare microchannel. Among several neutral polymers, poly(vinylalcohol) (PVA) and poly(dimethylacrylamide) coatings gave more suppressed and repeatable EOF with RSDs of less than 2.3%. The vacuum-drying method was also applicable to polyanions and polycations to provide accelerated and inversed EOF, respectively, with acceptable RSDs of less than 4.9%. In the microchip electrophoresis (MCE) analysis of bovine serum albumin (BSA) in the vacuum-dried and thermally-treated PVA coating channel, an almost symmetric peak of BSA was obtained, while in the native microchannel a significantly skewed peak was observed. The results demonstrated that the vacuum-dried polymer coatings were effective to control the EOF, and reduced the surface adsorption of proteins in MCE.

Fabrication of Fe3O4 Nanoparticle-coalesced Hydroxylated Multi-walled Carbon Nanotubes for the Analysis of Strychnine in Human Serum.

PubMed

Feng, Zufei; Xu, Yuehong; Wei, Shuguang; Zhang, Bao; Guan, Fanglin; Li, Shengbin

2015-01-01

A magnetic carbon nanomaterial for Fe3O4-modified hydroxylated multi-walled carbon nanotubes (Fe3O4-MWCNTs-OH) was prepared by the aggregating effect of Fe3O4 nanoparticles on MWCNTs-OH, and this material was combined with high-performance liquid chromatography (HPLC)/photodiode array detector (PAD) to determine strychnine in human serum samples. Some important parameters that could influence the extraction efficiency of strychnine were optimized, including the extraction time, amounts of Fe3O4-MWCNTs-OH, pH of sample solution, desorption solvent and desorption time. Under optimal conditions, the recoveries of spiked serum samples were between 98.3 and 102.7%, and the relative standard deviations (RSDs) ranged from 0.9 to 5.3%. The correlation coefficient was 0.9997. The LODs and LOQs of strychnine were 6.2 and 20.5 ng mL(-1), at signal-to-noise ratios of 3 and 10, respectively. These experimental results showed that the proposed method is feasible for the analysis of strychnine in serum samples.

QuEChERS-based extraction procedure for multifamily analysis of phytohormones in vegetables by UHPLC-MS/MS.

PubMed

Flores, María Isabel Alarcón; Romero-González, Roberto; Frenich, Antonia Garrido; Vidal, José Luis Martínez

2011-07-01

A new method has been developed and validated for the simultaneous analysis of different phytohormones (auxins, cytokinins and gibberellins) in vegetables. The compounds were extracted using a QuEChERS-based method (acronym of quick, easy, cheap, effective, rugged and safe). The separation and determination of the selected phytohormones were carried out by ultra high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS), using electrospray ionization source (ESI) in positive and negative ion modes. The method was validated and mean recoveries were evaluated at three concentration levels (50, 100 and 250 μg/kg), ranging from 75 to 110% at the three levels assayed. Intra- and interday precisions, expressed as relative standard deviations (RSDs), were lower than 20 and 25%, respectively. Limits of quantification (LOQs) were equal or lower than 10 μg/kg. The developed procedure was applied to seven courgette samples, and naphthylacetic acid, naphthylacetamide and benzyladenine were found in some of the analysed samples. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Application of solid phase extraction on multiwalled carbon nanotubes of some heavy metal ions to analysis of skin whitening cosmetics using ICP-AES.

PubMed

Alqadami, Ayoub A; Abdalla, Mohammad Abulhassan; AlOthman, Zeid A; Omer, Kamal

2013-01-14

A novel and highly sensitive method for the determination of some heavy metals in skin whitening cosmetics creams using multiwalled carbon nanotubes MWCNTs as solid phase extraction sorbent for the preconcentration of these heavy metals prior to their determination by inductively coupled plasma atomic emission spectrometry is described. Different practical parameters have been thoroughly investigated and the optimum experimental conditions were employed. The developed method was then applied for the determination of arsenic, bismuth, cadmium, mercury, lead and titanium in samples of skin whitening cosmetics. The detection limits under these conditions for As, Bi, Cd, Pb, Hg and Ti were 2.4, 4.08, 0.3, 2.1, 1.8, and 1.8 ng·mL-1, respectively. The relative standard deviations (RSDs) were found to be less than 2.0%. For validation, a certified reference material of NIST SRM 1570a spinach leaves was analyzed and the determined values were in good agreement with the certified values. The recoveries for spiked samples were found to be in the range of 89.6-104.4%.

Ultrasound assisted microextraction-nano material solid phase dispersion for extraction and determination of thymol and carvacrol in pharmaceutical samples: experimental design methodology.

PubMed

Roosta, Mostafa; Ghaedi, Mehrorang; Daneshfar, Ali; Sahraei, Reza

2015-01-15

In the present study, for the first time, a new extraction method based on "ultrasound assisted microextraction-nanomaterial solid phase dispersion (UAME-NMSPD)" was developed to preconcentrate the low quantity of thymol and carvacrol in pharmaceutical samples prior to their HPLC-UV separation/determination. The analytes were accumulated on nickel sulfide nanomaterial loaded on activated carbon (NiS-NP-AC) that with more detail identified by XRD, FESEM and UV-vis technique. Central composite design (CCD) combined with desirability function (DF) was used to search for optimum operational conditions. Working under optimum conditions specified as: 10 min ultrasonic time, pH 3, 0.011 g of adsorbent and 600 μL extraction solvent) permit achievement of high and reasonable linear range over 0.005-2.0 μg mL(-1) (r(2)>0.9993) with LOD of thymol and carvacrol as 0.23 and 0.21 μg L(-1), respectively. The relative standard deviations (RSDs) were less than 4.93% (n=3). Copyright © 2014 Elsevier B.V. All rights reserved.

Monolithic molecular imprinted polymer fiber for recognition and solid phase microextraction of ephedrine and pseudoephedrine in biological samples prior to capillary electrophoresis analysis.

PubMed

Deng, Dong-Li; Zhang, Ji-You; Chen, Chen; Hou, Xiao-Ling; Su, Ying-Ying; Wu, Lan

2012-01-06

A novel capillary electrophoresis (CE) method coupled with monolithic molecular imprinted polymer (MIP) fiber based solid phase microextraction (SPME) was developed for selective and sensitive determination of ephedrine (E) and pseudoephedrine (PE). With in situ polymerization in a silica capillary mold and E as template, the MIP fibers could be produced in batch reproducibly and each fiber was available for 50 extraction cycles without significant decrease in extraction ability. Using the MIP fiber under optimized extraction conditions, CE detection limits of E and PE were greatly lowered from 0.20 to 0.00096 μg/mL and 0.12 to 0.0011 μg/mL, respectively. Analysis of urine and serum samples by the MIP-SPME-CE method was also performed, with results indicating that E and PE could be selectively extracted. The recoveries and relative standard deviations (RSDs) for sample analysis were found in the range of 91-104% and 3.8-9.1%, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Multi-commutated fluorometric optosensor for the determination of citrinin in rice and red yeast rice supplements.

PubMed

Jiménez-López, J; Llorent-Martínez, E J; Ortega-Barrales, P; Ruiz-Medina, A

2014-01-01

Citrinin is a toxic secondary metabolite first isolated from Penicillium citrinum, although is also produced by other species of Penicillium and Aspergillus. It has highly toxic, mutagenic, teratogenic and carcinogenic properties and is often found in crops, vegetables and fruit. To our knowledge there is no specific legislation on maximum levels permitted for citrinin, so no official analytical method is currently available for its determination. Our laboratory developed a fluorometric flow-through optosensor using Sephadex SPC-25 as solid support. Multi-commutated flow injection analysis was used for the construction of the manifold and for handling solutions. In this way, we minimised waste generation and human intervention, which are critical aspects when dealing with highly toxic compounds such as citrinin. The optimum excitation/emission wavelengths were set at 330/494 nm; the calibration curve was linear in the concentration range 35-900 ng ml⁻¹. A detection limit of 10.5 ng ml⁻¹ and relative standard deviations (RSDs) lower than 3% were obtained. The developed optosensor was applied to the determination of citrinin in rice and dietary supplements containing red yeast rice.

Analysis of processing contaminants in edible oils. Part 2. Liquid chromatography-tandem mass spectrometry method for the direct detection of 3-monochloropropanediol and 2-monochloropropanediol diesters.

PubMed

MacMahon, Shaun; Begley, Timothy H; Diachenko, Gregory W

2013-05-22

A method was developed and validated for the detection of fatty acid diesters of 2-monochloropropanediol (2-MCPD) and 3-monochloropropanediol (3-MCPD) in edible oils. These analytes are potentially carcinogenic chemical contaminants formed during edible oil processing. After separation from oil matrices using a two-step solid-phase extraction (SPE) procedure, the target compounds are quantitated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). The first chromatographic conditions have been developed that separate intact diesters of 2-MCPD and 3-MCPD, allowing for their individual quantitation. The method has been validated for 28 3-MCPD diesters of lauric, myristic, palmitic, linolenic, linoleic, oleic, and stearic acids in coconut, olive, and palm oils, as well as 3 2-MCPD diesters, using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 88-118% (2-16% RSD) with maximum limits of quantitation of 30 ng/g (ppb).

Determination of chlorpyrifos and its metabolites in cells and culture media by liquid chromatography-electrospray ionization tandem mass spectrometry.

PubMed

Yang, Xiangkun; Wu, Xian; Brown, Kyle A; Le, Thao; Stice, Steven L; Bartlett, Michael G

2017-09-15

A sensitive method to simultaneously quantitate chlorpyrifos, chlorpyrifos oxon and the detoxified product 3,5,6-trichloro-2-pyridinol (TCP) was developed using either liquid-liquid extraction for culture media samples, or protein precipitation for cell samples. Multiple reaction monitoring in positive ion mode was applied for the detection of chlorpyrifos and chlorpyrifos oxon, and selected ion recording in negative mode was applied to detect TCP. The method provided linear ranges from 5 to 500, 0.2-20 and 20-2000ng/mL for media samples and from 0.5-50, 0.02-2 and 2-200ng/million cells for CPF, CPO and TCP, respectively. The method was validated using selectivity, linearity, precision, accuracy, recovery, stability and dilution tests. All relative standard deviations (RSDs) and relative errors (REs) for QC samples were within 15% (except for LLOQ, within 20%). This method has been successfully applied to study the neurotoxicity and metabolism of chlorpyrifos in a human neuronal model. Copyright © 2017 Elsevier B.V. All rights reserved.

Gas dispersion concentration of trace inorganic contaminants from fuel gas and analysis using head-column field-amplified sample stacking capillary electrophoresis.

PubMed

Yang, Jianmin; Li, Hai-Fang; Li, Meilan; Lin, Jin-Ming

2012-08-21

The presence of inorganic elements in fuel gas generally accelerates the corrosion and depletion of materials used in the fuel gas industry, and even leads to serious accidents. For identification of existing trace inorganic contaminants in fuel gas in a portable way, a highly efficient gas-liquid sampling collection system based on gas dispersion concentration is introduced in this work. Using the constructed dual path gas-liquid collection setup, inorganic cations and anions were simultaneously collected from real liquefied petroleum gas (LPG) and analyzed by capillary electrophoresis (CE) with indirect UV absorbance detection. The head-column field-amplified sample stacking technique was applied to improve the detection limits to 2-25 ng mL(-1). The developed collection and analytical methods have successfully determined existing inorganic contaminants in a real LPG sample in the range of 4.59-138.69 μg m(-3). The recoveries of cations and anions with spiked LPG samples were between 83.98 and 105.63%, and the relative standard deviations (RSDs) were less than 7.19%.

Planar solid phase extraction clean-up for pesticide residue analysis in tea by liquid chromatography-mass spectrometry.

PubMed

Oellig, Claudia; Schwack, Wolfgang

2012-10-19

Efficient clean-up is indispensable for preventing matrix effects in multi-residue analysis of pesticides in food by liquid and gas chromatography (LC and GC) coupled to mass spectrometry (MS). High-throughput planar solid phase extraction (HTpSPE) was recently introduced as a new clean-up concept in residue analysis of pesticides in fruit and vegetables (C. Oellig, W. Schwack, 2011 [45]). Thin-layer chromatography (TLC) was used to completely separate pesticides from matrix compounds and to focus them into a sharp zone, followed by extraction of the target zone by the TLC-MS interface. As rather challenging matrices, tea samples were chosen in this study. Besides chlorophylls and polyphenols, high amount of caffeine is co-extracted resulting in strong matrix effects both in LC-MS and GC-MS. The former HTpSPE procedure was adapted to initial extracts of green and black tea resulting in colorless extracts nearly free of matrix effects and interferences, as shown for seven chemically representative pesticides (acetamiprid, penconazole, azoxystrobin, chlorpyrifos, pirimicarb, fenarimol, and mepanipyrim). LC-MS/MS calibration curves obtained in the range of 0.002-0.5 mg/kg from matrix-matched standards and solvent standards were nearly identical and demonstrated the effectiveness of clean-up by HTpSPE. Mean recoveries determined by LC-MS/MS against solvent standards at spiking levels of 0.01 and 0.1 mg/kg ranged between 72 and 114% with relative standard deviations (RSDs) of 0.7-4.7% (n=4), while LC-MS measurements of tea samples spiked at 1 mg/kg provided recoveries of 81-104% with RSDs of 1.2-4.9% (n=6). Using LC-MS/MS, the method showed high sensitivity with signal-to-noise ratios>10 for concentrations below 0.002 mg/kg. HTpSPE of one sample was done in a few minutes, while numerous samples were cleaned in parallel at minimal costs with very low sample and solvent consumption. Copyright © 2012 Elsevier B.V. All rights reserved.

Evaluating the precision of passive sampling methods using ...

EPA Pesticide Factsheets

To assess these models, four different thicknesses of low-density polyethylene (LDPE) passive samplers were co-deployed for 28 days in the water column at three sites in New Bedford Harbor, MA, USA. Each sampler was pre-loaded with six PCB performance reference compounds (PRCs) to assess equilibrium status, such that the percent of PRC lost would range depending on PRC and LDPE thickness. These data allow subsequent Cfree comparisons to be made in two ways: (1) comparing Cfree derived from one thickness using different models and (2) comparing Cfree derived from the same model using different thicknesses of LDPE. Following the deployments, the percent of PRC lost ranged from 0-100%. As expected, fractional equilibrium decreased with increasing PRC molecular weight as well as sampler thickness. Overall, a total of 27 PCBs (log KOW ranging from 5.07 – 8.09) were measured at Cfree concentrations varying from 0.05 pg/L (PCB 206) to about 200 ng/L (PCB 28) on a single LDPE sampler. Relative standard deviations (RSDs) for total PCB measurements using the same thickness and varying model types range from 0.04-12% and increased with sampler thickness. Total PCB RSD for measurements using the same model and varying thickness ranged from: 6 – 30%. No RSD trends between models were observed but RSD did increase as Cfree decreased. These findings indicate that existing models yield precise and reproducible results when using LDPE and PRCs to measure Cfree. This work in

Zirconia coated stir bar sorptive extraction combined with large volume sample stacking capillary electrophoresis-indirect ultraviolet detection for the determination of chemical warfare agent degradation products in water samples.

PubMed

Li, Pingjing; Hu, Bin; Li, Xiaoyong

2012-07-20

In this study, a sensitive, selective and reliable analytical method by combining zirconia (ZrO₂) coated stir bar sorptive extraction (SBSE) with large volume sample stacking capillary electrophoresis-indirect ultraviolet (LVSS-CE/indirect UV) was developed for the direct analysis of chemical warfare agent degradation products of alkyl alkylphosphonic acids (AAPAs) (including ethyl methylphosphonic acid (EMPA) and pinacolyl methylphosphonate (PMPA)) and methylphosphonic acid (MPA) in environmental waters. ZrO₂ coated stir bar was prepared by adhering nanometer-sized ZrO₂ particles onto the surface of stir bar with commercial PDMS sol as adhesion agent. Due to the high affinity of ZrO₂ to the electronegative phosphonate group, ZrO₂ coated stir bars could selectively extract the strongly polar AAPAs and MPA. After systematically optimizing the extraction conditions of ZrO₂-SBSE, the analytical performance of ZrO₂-SBSE-CE/indirect UV and ZrO₂-SBSE-LVSS-CE/indirect UV was assessed. The limits of detection (LODs, at a signal-to-noise ratio of 3) obtained by ZrO₂-SBSE-CE/indirect UV were 13.4-15.9 μg/L for PMPA, EMPA and MPA. The relative standard deviations (RSDs, n=7, c=200 μg/L) of the corrected peak area for the target analytes were in the range of 6.4-8.8%. Enhancement factors (EFs) in terms of LODs were found to be from 112- to 145-fold. By combining ZrO₂ coating SBSE with LVSS as a dual preconcentration strategy, the EFs were magnified up to 1583-fold, and the LODs of ZrO₂-SBSE-LVSS-CE/indirect UV were 1.4, 1.2 and 3.1 μg/L for PMPA, EMPA, and MPA, respectively. The RSDs (n=7, c=20 μg/L) were found to be in the range of 9.0-11.8%. The developed ZrO₂-SBSE-LVSS-CE/indirect UV method has been successfully applied to the analysis of PMPA, EMPA, and MPA in different environmental water samples, and the recoveries for the spiked water samples were found to be in the range of 93.8-105.3%. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of parabens in beverage samples by dispersive liquid-liquid microextraction based on solidification of floating organic droplet.

PubMed

Hou, Fang; Deng, Xiaoying; Jiang, Xinyu; Yu, Jingang

2014-01-01

A simple and efficient method for dispersive liquid-liquid microextraction of methylparaben, ethylparaben, propylparaben and butylparaben in real beverage samples was developed. It is making use of solidified floating organic droplets of 1-dodecanol which has low density and a proper melting point. Parameters influencing the extraction efficiency, such as the type of extraction and dispersive solvent, the volume of extraction and dispersive solvent, salt effect, pH, extraction time, were optimized and resulted in enrichment factors (EFs) of 84 for methylparaben, 103 for ethylparaben, 115 for propylparaben and 126 for butylparaben. The limits of detection for parabens were 1.52, 1.06, 0.32 and 0.17 ng/mL, respectively. Excellent linearity with coefficients of correlation from 0.9970 to 0.9997 was observed in the concentration range of 5-1,000 ng/mL. The repeatability of the proposed method expressed as relative standard deviations (RSDs) ranged from 2.54 to 3.89% (n = 5). The relative recoveries for parabens in beverage samples were good and in the ranges of 89.8-109.9, 90.2-107.3, 90.9-101.7 and 92.3-118.1%, respectively. Thus, the proposed method has excellent potential for the determination of parabens in beverage samples. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Multi-residue determination of 210 drugs in pork by ultra-high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Yin, Zhiqiang; Chai, Tingting; Mu, Pengqian; Xu, Nana; Song, Yue; Wang, Xinlu; Jia, Qi; Qiu, Jing

2016-09-09

This paper presents a multi-residue analytical method for 210 drugs in pork using ultra-high-performance liquid chromatography-Q-Trap tandem mass spectrometry (UPLC-MS/MS) within 20min via positive ESI in scheduled multi-reaction monitoring (MRM) mode. The 210 drugs, belonging to 21 different chemical classes, included macrolides, sulfonamides, tetracyclines, β-lactams, β-agonists, aminoglycosides, antiviral drugs, glycosides, phenothiazine, protein anabolic hormones, non-steroidal anti-inflammatory drugs (NSAIDs), quinolones, antifungal drugs, corticosteroids, imidazoles, piperidines, piperazidines, insecticides, amides, alkaloids and others. A rapid and simple preparation method was applied to process the animal tissues, including solvent extraction with an acetonitrile/water mixture (80/20, v/v), defatting and clean-up processes. The recoveries ranged from 52% to 130% with relative standard deviations (RSDs)<20% for spiked concentrations of 10, 50 and 250μg/kg. More than 90% of the analytes achieved low limits of quantification (LOQs)<10μg/kg. The decision limit (CCα), detection capability (CCβ) values were in the range of 2-502μg/kg and 4-505μg/kg, respectively. This method is significant for food safety monitoring and controlling veterinary drug use. Copyright © 2016 Elsevier B.V. All rights reserved.

Carbon-Based Fe₃O₄ Nanocomposites Derived from Waste Pomelo Peels for Magnetic Solid-Phase Extraction of 11 Triazole Fungicides in Fruit Samples.

PubMed

Ren, Keyu; Zhang, Wenlin; Cao, Shurui; Wang, Guomin; Zhou, Zhiqin

2018-05-06

Carbon-based Fe₃O₄ nanocomposites (C/Fe₃O₄ NCs) were synthesized by a simple one-step hydrothermal method using waste pomelo peels as the carbon precursors. The characterization results showed that they had good structures and physicochemical properties. The prepared C/Fe₃O₄ NCs could be applied as excellent and recyclable adsorbents for magnetic solid phase extraction (MSPE) of 11 triazole fungicides in fruit samples. In the MSPE procedure, several parameters including the amount of adsorbents, extraction time, the type and volume of desorption solvent, and desorption time were optimized in detail. Under the optimized conditions, the good linearity ( R ² > 0.9916), the limits of detection (LOD), and quantification (LOQ) were obtained in the range of 1⁻100, 0.12⁻0.55, and 0.39⁻1.85 μg/kg for 11 pesticides, respectively. Lastly, the proposed MSPE method was successfully applied to analyze triazole fungicides in real apple, pear, orange, peach, and banana samples with recoveries in the range of 82.1% to 109.9% and relative standard deviations (RSDs) below 8.4%. Therefore, the C/Fe₃O₄ NCs based MSPE method has a great potential for isolating and pre-concentrating trace levels of triazole fungicides in fruits.

Pyrolytic in situ magnetization of metal-organic framework MIL-100 for magnetic solid-phase extraction.

PubMed

Huo, Shu-Hui; An, Hai-Yan; Yu, Jing; Mao, Xue-Feng; Zhang, Zhe; Bai, Lei; Huang, Yan-Feng; Zhou, Peng-Xin

2017-09-29

In this study, we report a facile, environmental friendly fabrication of a type of magnetic metal-organic framework (MOF) MIL-100 that can be used for magnetic solid-phase extraction (MSPE). The magnetic MOF composites were fabricated using in situ calcination method. The as-synthesized materials exhibited both high porosity and magnetic characteristics. They used for the MSPE of polycyclic aromatic hydrocarbons (PAHs) from water samples. Such MOF-based magnetic solid-phase extraction in combination with gas chromatography equipped with a flame ionization detector (GC-FID), exhibited wide linearity (0.02-250μgL -1 ), low detection limits (4.6-8.9ngL -1 ), and high enrichment factors (452-907) for PAHs. The relative standard deviations (RSDs) for intra- and inter-day extractions of PAHs were ranging from 1.7% to 9.8% and 3.8% to 9.2%, respectively. The recoveries for spiked PAHs (1μgL -1 ) in water samples were in the range of 88.5% to 106.6%. The results showed that the special anion-π orbital (electron donor-acceptor) interaction and π-π stacking between magnetic MIL-100 and PAHs play an important role in the adsorption of PAHs. Copyright © 2017. Published by Elsevier B.V.

A novel thermometric biosensor for fast surveillance of β-lactamase activity in milk.

PubMed

Zhou, Shuang; Zhao, Yunfeng; Mecklenburg, Michael; Yang, Dajin; Xie, Bin

2013-11-15

Regulatory restrictions on antibiotic residues in dairy products have resulted in the illegal addition of β-lactamase to lower antibiotic levels in milk in China. Here we demonstrate a fast, sensitive and convenient method based on enzyme thermistor (ET) for the surveillance of β-lactamase in milk. A fixed amount of penicillin G, which is a specific substrate of β-lactamase, was incubated with the milk sample, and an aliquot of the mixture was directly injected into the ET system to give a temperature change corresponding to the remained penicillin G. The amount of β-lactamase present in sample was deduced by the penicillin G consumed during incubation. This method was successfully applied to quantify β-lactamase in milk with the linear range of 1.1-20 UmL(-1) and the detection limit of 1.1 UmL(-1). The recoveries ranged from 93% to 105%, with relative standard deviations (RSDs) below 8%. The stability of the column equipped in ET was also studied, and only 5% decrease of activity was observed after 60 days of use. Compared with the conventional culture-based assay, the advantages of high throughput, timesaving and accurate quantification have made this method an ideal alternative for routine use. Copyright © 2013 Elsevier B.V. All rights reserved.

Dissipation behavior and risk assessment of butralin in soybean and soil under field conditions.

PubMed

Li, Congdi; Liu, Rong; Li, Li; Li, Wei; He, Yujian; Yuan, Longfei

2017-08-29

Dissipation behavior, final residue, and risk assessment of butralin in soybean, green soybean, plant, and soil were investigated. Butralin residues were extracted with acetonitrile and then soybean samples were detected with gas chromatography-mass spectrometer (GC-MS) and soil samples were determined with GC with nitrogen phosphorous detector (GC-NPD). The limit of quantification (LOQ) of the method was 0.01 mg/kg for soybean, green soybean, plant, and soil. Average recoveries ranged from 90.4 ~ 98.2% for green soybean, 86.2 ~ 86.6% for soybean, 86.0 ~ 98.8% for plant, and 85.0 ~ 106.8% for soil. The relative standard deviations (RSDs) were 2.0 ~ 7.2% for green soybean, 2.0 ~ 3.0% for soybean, 3.1 ~ 8.1% for plant, and 1.8 ~ 6.6% for soil. Half-lives of butralin in soil samples varied in the range of 11-22 days. At harvest time, final residues of butralin in soybean and green soybean were lower than LOQ. Risk assessment demonstrated that, at recommended dosage and frequency, butralin would not induce significant harm on humans. The study could be used as a quantitative basis for application of butralin on soybean.

[Determination of trivalent chromium and hexavalent chromium in dried edible fungi by microwave ashing-liquid chromatography with inductively coupled plasma mass spectrometry].

PubMed

Ni, Zhanglin; Tang, Fubin; Qu, Minghua; Mo, Runhong

2014-02-01

An analytical method using liquid chromatography with inductively coupled plasma mass spectrometry (LC-ICP-MS) for the determination of trivalent chromium (Cr(III)) and hexavalent chromium (Cr(VI)) in dried edible fungi was established. Edible fungi sample was ashed by a microwave ashing system and Na2 EDTA was added to the ashing sample to stabilize the Cr(III). An anion exchange column (250 mm x 4.6 mm, 10 microm) with a 60 mmol/L nitric acid (pH 9.3) solution as mobile phase was used for the separation and using ICP-MS as a detector for the determination of trivalent chromium and hexavalent chromium. The calibration curves were linear in the range of 0.5-50 microg/L and the correlation coefficients were 0. 999 9 for Cr(III) and Cr(VI). The average recoveries of Cr(III) and Cr(VI) ranged from 78.0% to 90.7% with the relative standard deviations (RSDs, n = 6) less than 4%. The limits of quantification (LOQ) of Cr(III) and Cr(VI) were 0.5 microg/L. The method is efficient, reliable and sensitive, and can meet the requirement for the determination of Cr(III) and Cr(VI) in dried edible fungi.

[Application of matrix solid-phase dispersion for the determination of phoxim in crucian carp samples by high performance liquid chromatography].

PubMed

Liu, Qian; Liu, Xiaoyu; Qiu, Chaokun; Wang, Xiaobao; Ren, Hongmin

2009-07-01

An analytical method was developed for the determination of phoxim residue in the muscle of crucian carp, which involved matrix solid-phase dispersion (MSPD) followed by high performance liquid chromatography (HPLC) with diode array detector. Under optimal conditions, 0.5 g tissue sample was dispersed with 1.5 g Florisil and 0.5 g anhydrous sodium sulphate, transferred to a cartridge. The cartridge was eluted with 25 mL acetone-hexane (40:60, v/v). The phoxim was separated on an ODS column (250 mm x 4.6 mm, 5 microm) with methanol-water (50:50, v/v) as the mobile phase at the flow rate of 0.6 mL/min, then detected by a diode array detector at 270 nm. The injection volume was 20 microL. The linear range of the method was 0.01 - 10 mg/L and the detection limit was 3.3 microg/kg. The average recoveries spiked at the levels of 0.05, 0.1, 1 mg/kg ranged from 88% to 112% with the relative standard deviations (RSDs) of 1.1% -6.3%. The method is quick, simple and can meet the requirement of the analysis of pesticide residues.

Application of a novel cold activated carbon fiber-solid phase microextraction for analysis of organochlorine pesticides in soil.

PubMed

Chai, Xiaolan; Jia, Jinping; Sun, Tonghua; Wang, Yalin; Liao, Liyan

2007-08-01

A novel and simple analytical procedure using cold activated carbon fiber-solid phase microextraction (CACF-SPME) was applied to determine organochlorine pesticides (OCs) in soil samples. The pesticides in this study consist of alpha -, beta -, gamma -, and delta -hexachlorocyclohexane (HCH). By heating the sample while cooling the fiber, the developed method not only provides better performance in terms of sensitivity, linearity and recovery but also offers shorter adsorption procedure than that of traditional headspace-solid phase microextraction (HS-SPME). The experimental conditions such as the amount of water, adsorption time and adsorption temperature were optimized. Matrix effects were investigated with different types of soils. We concluded that using the standard addition method was required for quantification purposes. The limits of detection obtained using the proposed method range from 0.01 to 0.05 ng/g, and the recoveries for CACF-SPME are in the range of 80.01% to 89.68% with relative standard deviation (RSDs) better than 8.60%. The proposed method was further applied to determine OCs in real agricultural soil. The results are in good agreement with those obtained using traditional ultrasonic extraction. The research demonstrates the suitability of the CACF-SPME for the analysis of OCs in soil.

Simultaneous Determination of 13 Priority Polycyclic Aromatic Hydrocarbons in Tehran’s Tap Water and Water for Injection Samples Using Dispersive Liquid-Liquid Micro Extraction Method and Gas Chromatography-Mass Spectrometry

PubMed Central

Sadeghi, Ramezan; Kobarfard, Farzad; Yazdanpanah, Hassan; Eslamizad, Samira; Bayate, Mitra

2016-01-01

Polycyclic aromatic hydrocarbons (PAHs) are classified as persistent and carcinogenic organic pollutants. PAHs contamination has been reported in water. Many of relevant regulatory bodies such as EU and EPA have regulated the limit levels for PAHs in drinking water. In this study, 13 priority polycyclic aromatic hydrocarbons (PAHs) were determined in tap water samples of Tehran and water for injection. Dispersive liquid-liquid microextraction procedure combined with gas chromatography-mass spectrometry was used for the extraction and determination of PAHs in the samples. Under the optimized conditions, the range of extraction recoveries and relative standard deviations (RSDs) of PAHs in water using internal standard (anthracene-d10) were in the range of 71-90% and 4-16%, respectively. Limit of detection for different PAHs were between 0.03 and 0.1 ngmL-1. The concentration of PAHs in all tap water as well as water for injection samples were lower than the limit of quantification of PAHs. This is the first study addressing the occurrence of PAHs in water for injection samples in Iran using dispersive liquid-liquid micro extraction procedure combined with gas chromatography-mass spectrometry. PMID:27642318

Determination of five pyrethroids in tea drinks by dispersive solid phase extraction with polyaniline-coated magnetic particles.

PubMed

Wang, Yuanpeng; Sun, Ying; Gao, Yan; Xu, Bo; Wu, Qiong; Zhang, Hanqi; Song, Daqian

2014-02-01

The polyaniline-coated magnetic particles with bowl-shaped morphology (Fe3O4/C/PANI microbowls) were successfully prepared and characterized by scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. The prepared microbowls were used as the magnetic adsorbent in dispersive solid phase extraction of five pyrethroids, including cyhalothrin, beta-cypermethrin, esfenvalerate, permethrin and bifenthrin in plain tea drinks. The effects of experiment factors, including amount of Fe3O4/C/PANI microbowls, pH value, ultrasound extraction time and desorption conditions, were investigated. The extraction recoveries obtained with 8 mg of magnetic microbowls were satisfactory, and the microbowls can be reused after easy washing. Thus, a simple, selective and effective method for the determination of the pyrethroids was established successfully. The results showed that the method had good linearity (r=0.9992-0.9998), and the limits of detections (LODs) were from 0.025 to 0.032 ng mL(-1). The intra-day and inter-day relative standard deviations (RSDs) were in the range of 2.4-6.1% and 3.5-8.8%, respectively. Recoveries obtained by analyzing the real tea drinks were in the range of 72.1-118.4%. © 2013 Published by Elsevier B.V.

Repeatability of the efficiency of columns packed with sub-3μm core-shell particles: Part I. 2.6μm Kinetex-C(18) particles in 4.6mm and 2.1mm×100mm column formats.

PubMed

Gritti, Fabrice; Guiochon, Georges

2012-08-24

The column-to-column repeatability of the mass transfer mechanism in columns packed with sub-3μm shell particles was investigated. The parameters of this mechanism were measured for twelve columns (six 2.1mm×100mm and six 4.6mm×100mm) packed with the same batch of 2.6μm Kinetex-C(18) particles (Phenomenex, CA, USA). For both series, the manufacturer provided columns at different positions in the efficiency distribution given by the quality test control. Three compounds were used, uracil, naphthalene and insulin. The reduced longitudinal diffusion term was measured with the peak parking (PP) method, the reduced solid-liquid mass transfer resistance term was given by a combination of the PP results and a model of effective diffusion in ternary composite materials (non-porous cores, concentric porous shell, and eluent matrix), validated previously. The overall eddy diffusion term was obtained by subtraction of these two HETP terms from the overall reduced HETP measured by numerical integration of the entire peak profiles. The results demonstrate that the dispersion of the column efficiencies is only due to the random nature of the packing process. At the highest reduced velocity achieved, the relative standard deviations (RSDs) of the eddy diffusion term for the 2.1mm I.D. columns were ca. 7% and 3% for the low molecular weight compounds and for insulin, respectively. For the 4.6mm I.D. columns, these RSDs were 15% and 5%, respectively. The larger RSDs for the 4.6mm I.D. columns is explained by the exceptionally low value of the eddy diffusion term. Copyright © 2012 Elsevier B.V. All rights reserved.

Chiral capillary electrophoresis with UV-excited fluorescence detection for the enantioselective analysis of 9-fluorenylmethoxycarbonyl-derivatized amino acids.

PubMed

Prior, Amir; Coliva, Giulia; de Jong, Gerhardus J; Somsen, Govert W

2018-05-29

The potential of capillary electrophoresis (CE) with ultraviolet (UV)-excited fluorescence detection for sensitive chiral analysis of amino acids (AAs) was investigated. DL-AAs were derivatized with 9-fluorenylmethoxycarbonyl chloride (FMOC)-Cl to allow their fluorescence detection and enhance enantioseparation. Fluorescence detection was achieved employing optical fibers, leading UV excitation light (< 300 nm) from a Xe-Hg lamp to the capillary window, and fluorescence emission to a spectrograph equipped with a charge-coupled device (CCD). Signal averaging over time and emission wavelength intervals was carried out to improve the signal-to-noise ratio of the FMOC-AAs. A background electrolyte (BGE) of 40 mM sodium tetraborate (pH 9.5), containing 15% isopropanol (v/v), 30 mM sodium dodecyl sulfate (SDS), and 30 mM β-cyclodextrin (β-CD), was found optimal for AA chemo- and enantioseparation. Enantioresolutions of 1.0 or higher were achieved for 16 proteinogenic DL-AAs. Limits of detection (LODs) were in the 10-100-nM range (injected concentration) for the D-AA enantiomers, except for FMOC-D-tryptophan (536 nM) which showed intramolecular fluorescence quenching. Linearity (R 2  > 0.997) and repeatability for peak height (relative standard deviations (RSDs) < 7.0%; n = 5) and electrophoretic mobility (RSDs < 0.6%; n = 5) of individual AA enantiomers were established for chiral analysis of DL-AA mixtures. The applicability of the method was investigated by the analysis of cerebrospinal fluid (CSF). Next to L-AAs, endogenous levels of D-glutamine and D-aspartic acid could be measured in CSF revealing enantiomeric ratios of 0.35 and 19.6%, respectively. This indicates the method's potential for the analysis of low concentrations of D-AAs in presence of abundant L-AAs.

Determination of phenolic acids and flavonoids in raw propolis by silica-supported ionic liquid-based matrix solid phase dispersion extraction high performance liquid chromatography-diode array detection.

PubMed

Wang, Zhibing; Sun, Rui; Wang, Yuanpeng; Li, Na; Lei, Lei; Yang, Xiao; Yu, Aimin; Qiu, Fangping; Zhang, Hanqi

2014-10-15

The silica-supported ionic liquid (S-SIL) was prepared by impregnation and used as the dispersion adsorbent of matrix solid phase dispersion (MSPD) for the simultaneous extraction of eight phenolic acids and flavonoids, including caffeic acid, ferulic acid, morin, luteolin, quercetin, apigenin, chrysin, and kaempferide in raw propolis. High performance liquid chromatography with a Zorbax SB-C18 column (150mm×4.6mm, 3.5μm) was used for separation of the analytes. The mobile phase consisted of 0.2% phosphoric acid aqueous solution and acetonitrile and the flow rate of the mobile phase was 0.5mL/min. The experimental conditions for silica-supported ionic liquid-based matrix solid phase dispersion (S-SIL-based MSPD) were optimized. S-SIL containing 10% [C6MIM]Cl was used as dispersant, 20mL of n-hexane as washing solvent and 15mL of methanol as elution solvent. The ratio of S-SIL to sample was selected to be 4:1. The standard curves showed good linear relationship (r>0.9995). The limits of detection and quantification were in the range of 5.8-22.2ngmL(-1) and 19.2-74.0ngmL(-1), respectively. The relative standard deviations (RSDs) of intra-day and inter-day determination were lower than 8.80% and 11.19%, respectively. The recoveries were between 65.51% and 92.32% with RSDs lower than 8.95%. Compared with ultrasound-assisted extraction (UAE) and soxhlet extraction, the present method consumed less sample, organic solvent, and extraction time, although the extraction yields obtained by S-SIL-based MSPD are slightly lower than those obtained by UAE. Copyright © 2014 Elsevier B.V. All rights reserved.

Wireless electrochemical preparation of gradient nanoclusters consisting of copper(II), stearic acid and montmorillonite on a copper wire for headspace in-tube microextraction of chlorobenzenes.

PubMed

Enteshari Najafabadi, Marzieh; Bagheri, Habib

2017-12-26

This work introduces a new gradient fiber coating for microextraction of chlorobenzenes. Nanoclusters of organoclay-Cu(II) on a copper wire were fabricated by wireless electrofunctionalization. The resultant gradient coatings are more robust, and thermally and mechanically stable. Wireless electrofunctionalization was carried out in a bipolar cell under a constant deposition potential and using an ethanolic electrolyte solution containing stearic acid and montmorillonite. Stearic acid acts as an inexpensive and green coating while montmorillonite acts as a modifier to impart thermal stability. The gradient morphology of the nanoclusters was investigated by scanning electron microscopy, thermogravimetric analysis and energy dispersive X-ray spectroscopy. The coated wire was placed in a hollow needle and used for headspace in-tube microextraction (HS-ITME) of chlorobenzenes (CBs). Effects of various parameters affecting synthesis and extraction were optimized. Following extraction, the needles were directly inserted into the GC injector, and the CBs (chlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene) were quantified by GC-MS. The limits of detection under optimized conditions range from 0.5 to 10 ng.L -1 . The intra- and inter-day relative standard deviations (RSDs) (for n = 10, 5 respectively) using a single fiber are 6-10 and 10-15%, respectively. The fiber-to-fiber RSDs (for n = 3) is between 17 and 24%. The method was successfully applied to the extraction of CBs from real water samples, and relative recoveries are between 91 and 110%. Graphical abstract A gradient coating of organoclay-Cu nanoclusters was fabricated on a copper wire by wireless electrofunctionalization. The oxidation of copper takes place at the anodic pole (red) while dissolved oxygen in ethanol solution is reduced at the cathodic pole (blue).

Hollow mesoporous structured molecularly imprinted polymer as adsorbent in pipette-tip solid-phase extraction for the determination of antiretrovirals from plasma of HIV-infected patients.

PubMed

Simões, Nathália Soares; de Oliveira, Hanna Leijoto; da Silva, Ricky Cássio Santos; Teixeira, Leila Suleimara; Sales, Thaís Lorenna Souza; de Castro, Whocely Victor; de Paiva, Maria José Nunes; Sanches, Cristina; Borges, Keyller Bastos

2018-05-17

In this work a hollow mesoporous structured molecularly imprinted polymer was synthetized and used as adsorbent in pipette-tip solid-phase extraction for the determination of lamivudine (3TC), zidovudine (AZT) and efavirenz (EFZ) from plasma of human immunodeficiency virus (HIV) infected patients by high-performance liquid chromatography (HPLC). All parameters that influence the recovery of the pipette tip based on hollow mesoporous molecularly imprinted polymer solid-phase extraction (PT-HM-MIP-SPE) method were systematically studied and discussed in detail. The adsorbent material was prepared using methacrylic acid and 4-vinylpyridine as functional monomers, ethylene glycol dimethacrylate as crosslinker, acetonitrile as solvent, 4,4'-azobis(4-cyanovaleric acid) as radical initiator, benzalkonium chloride as surfactant), 3TC, and AZT as templates. The simultaneous separation of 3TC, AZT and EFZ by HPLC-UV was performed using a Gemini C18 Phenomenexࣨ column (250 mm × 4.6 mm, 5 μm) and mobile phase consisting of acetonitrile: water pH 3.2 (68:32, v/v), flow rate of 1.0 mL min -1 and λ = 260 nm. The method was linear over the concentration range from 0.25 to 10 μg mL -1 for 3TC and EFZ, and 0.05 to 2.0 μg mL -1 for AZT, with correlation coefficients larger than 0.99 for all analytes. Recovery ± relative standard deviations (RSDs %) were 41.99±2.38 %, 82.29±1.63 %, and 83.72±7.52 % for 3TC, AZT, and EFZ, respectively. The RSDs and relative errors (REs) were lower than 15 % for intra and interday assays. The method has been successfully applied for monitoring HIV-infected patients outside the therapeutic dosage.2 This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Preparation of novel alumina nanowire solid-phase microextraction fiber coating for ultra-selective determination of volatile esters and alcohols from complicated food samples.

PubMed

Zhang, Zhuomin; Ma, Yunjian; Wang, Qingtang; Chen, An; Pan, Zhuoyan; Li, Gongke

2013-05-17

A novel alumina nanowire (ANW) solid-phase microextraction (SPME) fiber coating was prepared by a simple and rapid anodization-chemical etching method for ultra-selective determination of volatile esters and alcohols from complicated food samples. Preparation conditions for ANW SPME fiber coating including corrosion solution concentration and corrosion time were optimized in detail for better surface morphology and higher surface area based on scanning electron microscope (SEM). Under the optimum conditions, homogeneous alumina nanowire structure of ANW SPME fiber coating was achieved with the average thickness of 20 μm around. Compared with most of commercial SPME fiber coatings, ANW SPME fiber coatings achieved the higher extraction capacity and special selectivity for volatile esters and alcohols. Finally, an efficient gas sampling technique based on ANW SPME fiber coating as the core was established and successfully applied for the ultra-selective determination of trace volatile esters and alcohols from complicated banana and fermented glutinous rice samples coupled with gas chromatography/mass spectrometry (GC/MS) detection. It was interesting that 25 esters and 2 alcohols among 30 banana volatile organic compounds (VOCs) identified and 4 esters and 7 alcohols among 13 identified VOCs of fermented glutinous rice were selectively sampled by ANW SPME fiber coatings. Furthermore, new analytical methods for the determination of some typical volatile esters and alcohols from banana and fermented glutinous rice samples at specific storage or brewing phases were developed and validated. Good recoveries for banana and fermented glutinous rice samples were achieved in range of 108-115% with relative standard deviations (RSDs) of 2.6-6.7% and 80.0-91.8% with RSDs of 0.3-1.3% (n=3), respectively. This work proposed a novel and efficient gas sampling technique of ANW SPME which was quite suitable for ultra-selectively sampling trace volatile esters and alcohols from complicated food samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Development of QuEChERS-based extraction and liquid chromatography-tandem mass spectrometry method for quantifying flumethasone residues in beef muscle.

PubMed

Park, Ki Hun; Choi, Jeong-Heui; Abd El-Aty, A M; Cho, Soon-Kil; Park, Jong-Hyouk; Kwon, Ki Sung; Park, Hee Ra; Kim, Hyung Soo; Shin, Ho-Chul; Kim, Mi Ra; Shim, Jae-Han

2012-12-01

A rapid, specific, and sensitive method based on liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in the positive ion mode using multiple reaction monitoring (MRM) was developed and validated to quantify flumethasone residues in beef muscle. Methods were compared between the original as well as the EN quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based extraction. Good linearity was achieved at concentration levels of 5-30 μg/kg. Estimated recovery rates at spiking levels of 5 and 10 μg/kg ranged from 72.1 to 84.6%, with relative standard deviations (RSDs)<7%. The results of the inter-day study, which was performed by fortifying beef muscle samples (n=18) on 3 separate days, showed an accuracy of 93.4-94.4%. The precision (expressed as relative standard deviation values) for the inter-day variation at two levels of fortification (10 and 20 μg/kg) was 1.9-5.2%. The limit of detection (LOD) and limit of quantitation (LOQ) were 1.7 and 5 μg/kg, at signal-to-noise ratios (S/Ns) of 3 and 10, respectively. The method was successfully applied to analyze real samples obtained from large markets throughout the Korean Peninsula. The method proved to be sensitive and reliable and, thus, rendered an appropriate means for residue analysis studies. Copyright © 2012 Elsevier Ltd. All rights reserved.

[High performance liquid chromatogram (HPLC) determination of adenosine phosphates in rat myocardium].

PubMed

Miao, Yu; Wang, Cheng-long; Yin, Hui-jun; Shi, Da-zhuo; Chen, Ke-ji

2005-04-18

To establish method for the quantitative determination of adenosine phosphates in rat myocardium by optimized high performance liquid chromatogram (HPLC). ODS HYPERSIL C(18) column and a mobile phase of 50 mmol/L tribasic potassium phosphate buffer solution (pH 6.5), with UV detector at 254 nm were used. The average recovery rates of myocardial adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were 99%-107%, 96%-104% and 95%-119%, respectively; relative standard deviations (RSDs) of within-day and between-days were less than 1.5% and 5.1%, respectively. The method is simple, rapid and accurate, and can be used to analyse the adenosine phosphates in myocardium.

Preparation and characterization of magnetic Wells-Dawson heteropoly acid nanoparticles for magnetic solid-phase extraction of aromatic amines in water samples.

PubMed

Amiri, Amirhassan; Saadati-Moshtaghin, Hamid Reza; Zonoz, Farokhzad Mohammadi; Targhoo, Azadeh

2017-02-03

In this work, aminopropyl modified silica-coated magnetite nanoparticles with Wells-Dawson heteropoly acid (P 2 W 17 Fe@APSCMNPs) was first synthesized and underwent highly efficient magnetic solid-phase extraction (MSPE) of aromatic amines from aqueous samples. The resulted nanomaterials were characterized with different physicochemical techniques such as Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). Aniline, N,N-dimethylaniline, o-toluidine and 3-chloroaniline were selected as target compounds. The sample quantification was carried out using gas chromatography-flame ionization detector (GC-FID). Under optimal working conditions, the developed method showed good linearity (R>0.9912) in the range of 0.01-100ngmL -1 . The method displays detection limits (at an S/N ration of 3) in the range from 0.003 to 0.01ngmL -1 , and the limits of quantification (at an S/N ratio of 10) are between 0.01 and 0.04ngmL -1 . The enrichment factors (EFs) were in the range of 75-113. Relative standard deviations (RSDs) are 4.8-8.3%. The applicability of the developed method was examined by analyzing different water samples (river water, tap water, well water and wastewater) and the relative recovery values for the spiked water samples were found to be in the range of 90.7-99.8%. Copyright © 2016 Elsevier B.V. All rights reserved.

Method development for gypenosides fingerprint by high performance liquid chromatography with diode-array detection and the addition of internal standard.

PubMed

Liu, Fang; Ren, Dequan; Guo, De-an; Pan, Yifeng; Zhang, Huzhe; Hu, Ping

2008-03-01

In this paper, a new method for liquid chromatographic fingerprint of saponins in Gynostemma pentaphyllum (THUNB.) MAKINO was developed. The G. pentaphyllum powder was defatted by Soxhlet extraction with petroleum ether and then gypenosides were extracted from the residue with methanol by sonicating. Column chromatography with macro pore resin was then used to separate and enrich gypenosides. HPLC fingerprint analysis of gypenosides fraction was performed on a C18 column, with an isocratic elution of 34% acetonitrile for 60 min at 0.8 ml/min, sample injection volume was 20 microl and the wavelength was 203 nm. To cover the lack of standard compounds, the addition of an internal standard of ginsenoside Rb2 was employed in the gypenosides fingerprint profile. The relative retention time (RRT) and relative peak area (RPA) of the gypenosides peaks in the fingerprint were calculated by setting the ginsenoside Rb2 as the marker compound. The relative standard deviation (RSDs) of RRT of five common peaks vs. ginsenoside Rb2 in precision, repeatability and stability test were less than 1%, and the RSDs of RPA were less than 5%. The method validation data proved that the proposed method for the fingerprint with internal standard of G. pentaphyllum saponins is adequate, valid and applicable. Finally, three batches of crude drug samples collected from Shanxi province were tested by following the established method.

Simultaneous determination of 13 phytohormones in oilseed rape tissues by liquid chromatography-electrospray tandem mass spectrometry and the evaluation of the matrix effect.

PubMed

Fan, Sufang; Wang, Xiupin; Li, Peiwu; Zhang, Qi; Zhang, Wen

2011-03-01

In the experiment, a high-performance liquid chromatography and electrospray ionization-tandem mass spectrometry with selected reaction monitoring was used to simultaneously determine various classes of phytohormones, including indole-3-acetic acid, α-naphthaleneacetic acid, 2-chlorobenzoic acid, 4-chlorobenzoic acid, indole-3-butyric acid, gibberellic acid, 2,4-dichlorophenoxyacetic acid, 2-naphthoxyacetic acid, abscisic acid, 2,3,5-triiodobenzoic acid, uniconazole, paclobutrazol and 2,4-epibassinolide in rape tissues. The analyses were separated by an HPLC equipped with a reversed-phase column using a binary solvent system composed of methanol and water, both containing 0.1% of formic acid. The matrix effect was also considered and determined. The technology was applied to analyze rape tissues, including roots, stems, leaves, flowers, immature pods and rape seeds. The rape tissues were subjected to ultrasound-assisted extraction and purified by dispersive solid-phase extraction, and then transferred into the liquid chromatography system. The detection limit for each plant hormone was defined by the ratio of signal/background noise (S/N) of 3. The results showed perfect linearity (R(2) values of 0.9987-1.0000) and reproducibility of elution times (relative standard deviations, RSDs,<1%) and peak areas (RSDs,<7%) for all target compounds. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrasound-assisted temperature-controlled ionic liquid emulsification microextraction coupled with capillary electrophoresis for the determination of parabens in personal care products.

PubMed

Ma, Teng; Li, Zheng; Jia, Qiong; Zhou, Weihong

2016-07-01

We developed a CE and ultrasound-assisted temperature-controlled ionic liquid emulsification microextraction method for the determination of four parabens (methyl paraben, ethyl paraben, propyl paraben, and butyl paraben) in personal care products including mouthwash and toning lotion. In the proposed extraction procedure, ionic liquid (IL, 1-octyl-3-methylimidazolium hexafluorophosphate) was used as extraction solvent, moreover, no disperser solvent was needed. Parameters affecting the extraction efficiency including volume of IL, heating temperature, ultrasonic time, extraction time, sample pH, ionic strength, and centrifugation time were optimized. Under the optimized conditions, the method was found to be linear over the range of 3-500 ng/mL with coefficient of determination (R(2) ) in the range of 0.9990-0.9998. The LODs and LOQs for the four parabens were 0.45-0.72 ng/mL and 1.50-2.40 ng/mL, respectively. Intraday and interday precisions (RSDs, n = 5) were in the range of 5.4-6.8% and 7.0-8.7%, respectively. The recoveries of parabens at different spiked levels ranged from 71.9 to 119.2% with RSDs less than 9.5%. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selective determination of caffeine in foods with 3D-graphene based ultrasound-assisted magnetic solid phase extraction.

PubMed

Rahimi, Afshin; Zanjanchi, Mohammad Ali; Bakhtiari, Sadjad; Dehsaraei, Mohammad

2018-10-01

An efficient method was applied for extraction of caffeine in food samples. Three-dimensional graphene-Fe 3 O 4 (3D-G-Fe 3 O 4 ) nanoparticles was successfully synthesized and used as adsorbent in magnetic solid phase extraction (MSPE) step. The properties of synthesized adsorbent were characterized by fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods. The influence of main parameters of extraction procedure such as ultrasound parameter, amount of nanoparticles, pH, salt concentration and desorption condition were investigated and optimized. Under the optimized experimental conditions, the figure of merit results showed excellent linear dynamic range (LDR) of 0.5-500 µg mL -1 , with determination coefficient (R 2 ) higher than 0.996 and limit of detection (LOD) of 0.1 µg mL -1 . Intra- and inter-day relative standard deviations (RSDs) were less than 5.9 and 7.1%, respectively. The method was successfully applied for determination of caffeine in different food samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

[Simultaneous determination of seven residual solvents in bovis calculus artifactus by headspace gas chromatography].

PubMed

Chi, Shuyao; Wu, Dike; Sun, Jinhong; Ye, Ruhan; Wang, Xiaoyan

2014-05-01

A headspace gas chromatography (HS-GC) method was developed for the simultaneous determination of seven residual solvents (petroleum ether (60-90 degrees C), acetone, ethyl acetate, methanol, methylene chloride, ethanol and butyl acetate) in bovis calculus artifactus. The DB-WAX capillary column and flame ionization detector (FID) were used for the separation and detection of the residual solvents, and the internal standard method was used for the quantification. The chromatographic conditions, such as equilibrium temperature and equilibrium time, were optimized. Under the optimized conditions, all of the seven residual solvents showed good linear relationships with good correlation coefficients (not less than 0.999 3) in the prescribed concentration range. At three spiked levels, the recoveries for the seven residual solvents were 94.7%-105.2% with the relative standard deviations (RSDs) less than 3.5%. The limits of detection (LODs) of the method were 0.43-5.23 mg/L, and the limits of quantification (LOQs) were 1.25-16.67 mg/L. The method is simple, rapid, sensitive and accurate, and is suitable for the simultaneous determination of the seven residual solvents in bovis calculus artifactus.

Analysis of trace dicyandiamide in stream water using solid phase extraction and liquid chromatography UV spectrometry.

PubMed

Qiu, Huidong; Sun, Dongdi; Gunatilake, Sameera R; She, Jinyan; Mlsna, Todd E

2015-09-01

An improved method for trace level quantification of dicyandiamide in stream water has been developed. This method includes sample pretreatment using solid phase extraction. The extraction procedure (including loading, washing, and eluting) used a flow rate of 1.0mL/min, and dicyandiamide was eluted with 20mL of a methanol/acetonitrile mixture (V/V=2:3), followed by pre-concentration using nitrogen evaporation and analysis with high performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV). Sample extraction was carried out using a Waters Sep-Pak AC-2 Cartridge (with activated carbon). Separation was achieved on a ZIC(®)-Hydrophilic Interaction Liquid Chromatography (ZIC-HILIC) (50mm×2.1mm, 3.5μm) chromatography column and quantification was accomplished based on UV absorbance. A reliable linear relationship was obtained for the calibration curve using standard solutions (R(2)>0.999). Recoveries for dicyandiamide ranged from 84.6% to 96.8%, and the relative standard deviations (RSDs, n=3) were below 6.1% with a detection limit of 5.0ng/mL for stream water samples. Copyright © 2015. Published by Elsevier B.V.

Multiclass analysis of antibiotic residues in honey by ultraperformance liquid chromatography-tandem mass spectrometry.

PubMed

Vidal, Jose Luis Martínez; Aguilera-Luiz, María Del Mar; Romero-González, Roberto; Frenich, Antonia Garrido

2009-03-11

A method has been developed and validated for the simultaneous analysis of different veterinary drug residues (macrolides, tetracyclines, quinolones, and sulfonamides) in honey. Honey samples were dissolved with Na(2)EDTA, and veterinary residues were extracted from the supernatant by solid-phase extraction (SPE), using OASIS HLB cartridges. The separation and determination was carried out by ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS), using an electrospay ionization source (ESI) in positive mode. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM) of two ion transitions per compound to provide a high degree of sensitivity and specificity. The method was validated, and mean recoveries were evaluated at three concentration levels (10, 50, and 100 microg/kg), ranging from 70 to 120% except for doxycycline, erythromycin, and tylmicosin with recovery higher than 50% at the three levels assayed. Relative standard deviations (RSDs) of the recoveries were less than 20% within the intraday precision and less than 25% within the interday precision. The limits of quantification (LOQs) were always lower than 4 microg/kg. The developed procedure was applied to 16 honey samples, and erythromycin, sarafloxacin, and tylosin were found in a few samples.

Study of weathering effects on the distribution of aromatic steroid hydrocarbons in crude oils and oil residues.

PubMed

Wang, Chuanyuan; Chen, Bing; Zhang, Baiyu; Guo, Ping; Zhao, Mingming

2014-01-01

The composition and distribution of triaromatic steroid hydrocarbons in oil residues after biodegradation and photo-oxidation processes were detected, and the diagnostic ratios for oil spill identification were developed and evaluated based on the relative standard deviation (RSD) and the repeatability limit. The preferential loss of C27 methyl triaromatic steranes (MTAS) relative to C28 MTAS and C29 MTAS was shown during the photo-oxidation process. In contrast to the photochemical degradation, the MTAS with the original 20R biological configuration was preferentially degraded during the biodegradation process. The RSD of most of the diagnostic ratios of MTAS ranged from 9 to 84% during the photo-oxidation process. However, the RSDs of such ratios derived from MTAS were all <5% even in high biodegradation, and such parameters may also provide new methods on oil spill identification. The parameters of monoaromatic sterane and monoaromatic sterane are not used well for oil spill identification after photo-oxidation. The triaromatic steroid hydrocarbons retained their molecular compositions after biodegradation and photo-oxidation and most of the diagnostic ratios derived from them could be efficiently used in oil spill identification.

Low-temperature plasma-probe mass spectrometry based method for determination of new psychoactive substances in oral fluid.

PubMed

Wang, Xiaochen; Hua, Zhendong; Yang, Zhaoguang; Li, Haipu; Liu, Huwei; Qiu, Bo; Nie, Honggang

2018-06-15

Owing to the widespread abuse of new psychoactive substances (NPSs), developing a rapid, easily operable method to detect NPSs in oral fluid is of high priority. Their ease of collection and non-invasive nature make oral fluid samples suitable for on-site tests and forensic cases. Herein we report a rapid and sensitive method to screen and quantitate 11 new NPSs in oral fluid. Low-temperature plasma-probe mass spectrometry (LTP-MS) was applied and, to improve the signal intensity, thermally assisted desorption was employed. Tandem mass spectrometry was performed to exclude false positive signals and to decrease noise at the m/z values of interest. Linearity was studied using matrix-matched calibration curves; all the analytes exhibited good linearity with R 2 varying from 0.9907 to 0.9981. The estimated limits of detection (LODs) were in the range of 3.0-15.2 ng/mL, which are comparable to those of immunoassay; relative standard deviations (RSDs) are no greater than 23% at the studied concentration levels. The proposed LTP-MS-based method was promising in forensic and on-site applications to curb the abuse of NPSs. Copyright © 2018 John Wiley & Sons, Ltd.

Metal-Organic Framework-Polymer Composite as a Highly Efficient Sorbent for Sulfonamide Adsorption and Desorption: Effect of Coordinatively Unsaturated Metal Site and Topology.

PubMed

Shih, Yung-Han; Wang, Kuen-Yun; Singco, Brenda; Lin, Chia-Her; Huang, Hsi-Ya

2016-11-08

In this study, we first demonstrated the effect of two types of metal-organic framework-polymer (MOF-polymer) monoliths on in-tube solid-phase microextraction (IT-SPME) of sulfonamides. Sulfonamides were successfully adsorbed onto MIL-101(Cr)-polymer but were difficult to elute due to these sulfonamides could interact via Lewis acid-base interaction with the presence of Cr(III) coordinatively unsaturated metal sites (CUS). Moreover, the cage-type topology of MIL-101(Cr) that could produce multiple pathways thus complicates the desorption of the test analytes from the sorbent. Contrastingly, MIL-53(Al)-polymer provided weaker Al(III) CUS, and its one-dimensional channel pore structure could provide an unhindered pathway for sulfonamides transfer during elution. After optimizing the IT-SPME condition such as MOF content, pH of sample matrix, column length, extraction flow rate, and elution volume, the calculated extraction recovery of sulfonamides in MIL-53(Al)-polymer as analyzed by microemulsion electrokinetic chromatography (MEEKC) were in the range of 40%-90% with relative standard deviations (RSDs) below 5% and a reusability of at least 30 times.

Ultrasound-assisted emulsification microextraction for determination of 2,4,6-trichloroanisole in wine samples by gas chromatography tandem mass spectrometry.

PubMed

Fontana, Ariel R; Patil, Sangram H; Banerjee, Kaushik; Altamirano, Jorgelina C

2010-04-28

A fast and effective microextraction technique is proposed for preconcentration of 2,4,6-trichloroanisole (2,4,6-TCA) from wine samples prior gas chromatography tandem mass spectrometric (GC-MS/MS) analysis. The proposed technique is based on ultrasonication (US) for favoring the emulsification phenomenon during the extraction stage. Several variables influencing the relative response of the target analyte were studied and optimized. Under optimal experimental conditions, 2,4,6-TCA was quantitatively extracted achieving enhancement factors (EF) > or = 400 and limits of detection (LODs) 0.6-0.7 ng L(-1) with relative standard deviations (RSDs) < or = 11.3%, when 10 ng L(-1) 2,4,6-TCA standard-wine sample blend was analyzed. The calibration graphs for white and red wine were linear within the range of 5-1000 ng L(-1), and estimation coefficients (r(2)) were > or = 0.9995. Validation of the methodology was carried out by standard addition method at two concentrations (10 and 50 ng L(-1)) achieving recoveries >80% indicating satisfactory robustness of the method. The methodology was successfully applied for determination of 2,4,6-TCA in different wine samples.

An organically modified silica aerogel for online in-tube solid-phase microextraction.

PubMed

Bu, Yanan; Feng, Juanjuan; Tian, Yu; Wang, Xiuqin; Sun, Min; Luo, Chuannan

2017-09-29

Aerogels have received considerable attentions because of its porous, high specific surface, unique properties and environmental friendliness. In this work, an organically modified silica aerogel was functionalized on the basalt fibers (BFs) and filled into a poly(ether ether ketone) (PEEK) tube, which was coupled with high performance liquid chromatography (HPLC) for in-tube solid-phase microextraction (IT-SPME). The aerogel was characterized by scanning electron microscopy (SEM) and fourier transform infrared spectrometry (FT-IR). The extraction efficiency of the tube was systematically investigated and shown enrichment factors from 2346 to 3132. An automated, sensitive and selective method was developed for the determination of five estrogens. The linear range was from 0.03 to 100μgL -1 with correlation coefficients (r) higher than 0.9989, and low detection limits (LODs) were 0.01-0.05μgL -1 . The relative standard deviations (RSDs) for intra-day and inter-day were less than 4.5% and 6.7% (n=6), respectively. Finally, the analysis method was successfully applied to detect estrogens in sewage and emollient water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of endogenous aldehydes in human urine by static headspace gas chromatography-mass spectrometry.

PubMed

Serrano, María; Gallego, Mercedes; Silva, Manuel

2016-03-11

Endogenous aldehydes (EAs) generated during oxidative stress and cell processes are associated with many pathogenic and toxicogenic processes. The aim of this research was to develop a solvent-free and automated analytical method for the determination of EAs in human urine using a static headspace generator sampler coupled with gas chromatography-mass spectrometry (HS-GC-MS). Twelve significant EAs used as markers of different biochemical and physiological processes, namely short- and medium-chain alkanals, α,β-unsaturated aldehydes and dicarbonyl aldehydes have been selected as target analytes. Human urine samples (no dilution is required) were derivatized with O-2,3,4,5,6-pentafluorobenzylhydroxylamine in alkaline medium (hydrogen carbonate-carbonate buffer, pH 10.3). The HS-GC-MS method developed renders an efficient tool for the sensitive and precise determination of EAs in human urine with limits of detection from 1 to 15ng/L and relative standard deviations, (RSDs) from 6.0 to 7.9%. Average recoveries by enriching urine samples ranged between 92 and 95%. Aldehydes were readily determined at 0.005-50μg/L levels in human urine from healthy subjects, smokers and diabetic adults. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of Solid Phase Extraction on Multiwalled Carbon Nanotubes of Some Heavy Metal Ions to Analysis of Skin Whitening Cosmetics Using ICP-AES

PubMed Central

ALqadami, Ayoub A.; Abdalla, Mohammad Abulhassan; ALOthman, Zeid A.; Omer, Kamal

2013-01-01

A novel and highly sensitive method for the determination of some heavy metals in skin whitening cosmetics creams using multiwalled carbon nanotubes MWCNTs as solid phase extraction sorbent for the preconcentration of these heavy metals prior to their determination by inductively coupled plasma atomic emission spectrometry is described. Different practical parameters have been thoroughly investigated and the optimum experimental conditions were employed. The developed method was then applied for the determination of arsenic, bismuth, cadmium, mercury, lead and titanium in samples of skin whitening cosmetics. The detection limits under these conditions for As, Bi, Cd, Pb, Hg and Ti were 2.4, 4.08, 0.3, 2.1, 1.8, and 1.8 ng·mL−1, respectively. The relative standard deviations (RSDs) were found to be less than 2.0%. For validation, a certified reference material of NIST SRM 1570a spinach leaves was analyzed and the determined values were in good agreement with the certified values. The recoveries for spiked samples were found to be in the range of 89.6–104.4%. PMID:23343988

[Determination of 14 heterocyclic aromatic amines in wine by liquid chromatography-ion trap-time of flight tandem mass spectrometry].

PubMed

Wang, Min; Guo, Dehua; Ding, Zhuoping; Yao, Jinting; Li, Fengge; Su, Min

2012-07-01

A rapid qualitative and quantitative analytical method was developed for the simultaneous determination of 14 heterocyclic aromatic amines (HAAs) in wine by liquid chromatography-ion trap-time of flight tandem mass spectrometry (LC-IT-TOF MS). HAAs were extracted from the samples by ethyl acetate under alkaline condition. The quantitation was carried out using internal standard method. The separation of HAAs was carried out based on Phenomenex Kinetex C18 100A column (100 mm x 2.1 mm, 2.6 microm), with a gradient elution of acetonitrile and 30 mmol/L ammonium formate at a flow rate of 0.4 mL/min. The analytes were detected under positive-ion electrospray ionization mode. The results showed that the linear ranges of the 14 HAAs were 1-500 microg/L with limits of detection (signal/noise = 3) of 0.33-1.77 microg/L. The average recoveries of all the compounds spiked in wine samples at three levels of 10, 50, 100 microg/L were in the ranges of 71.6%-96.4%, 72.9%-101.9%, 74.5%-103.3%, with the corresponding relative standard deviations (RSDs, n = 6) of 2.9%-7.9%, 1.7%-5.3%, 1.8%-4.8%, respectively. The established method is simple, rapid, accurate, and has wide linear range and high sensitivity. It can be applied to the simultaneous analysis of the HAAs in wine.

Dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection to determination of opium alkaloids in human plasma.

PubMed

Ahmadi-Jouibari, Toraj; Fattahi, Nazir; Shamsipur, Mojtaba; Pirsaheb, Meghdad

2013-11-01

A novel, simple, rapid and sensitive dispersive liquid-liquid microextraction method based on the solidification of floating organic drop (DLLME-SFO) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was used to determine opium alkaloids in human plasma. During the extraction procedure, plasma protein was precipitated by using a mixture of zinc sulfate solution and acetonitrile. Some effective parameters on extraction were studied and optimized. Under the optimum conditions (extraction solvent: 30.0 μl 1-undecanol; disperser solvent: 470 μl acetone; pH: 9; salt addition: 1%(w/v) NaCl and extraction time: 0.5 min), calibration curves are linear in the range of 1.5-1000 μgl(-1) and limit of detections (LODs) are in the range of 0.5-5 μgl(-1). The relative standard deviations (RSDs) for 100 μgl(-1) of morphine and codeine, 10.0 μgl(-1) of papaverine and 20.0 μgl(-1) of noscapine in diluted human plasma are in the range of 4.3-7.4% (n=5). Finally, the method was successfully applied in the determination of opium alkaloids in the actual human plasma samples. The relative recoveries of plasma samples spiked with alkaloids are 88-110.5%. The obtained results show that DLLME-SFO combined with HPLC-UV is a fast and simple method for the determination of opium alkaloids in human plasma. Copyright © 2013 Elsevier B.V. All rights reserved.

Magnetized graphene layers synthesized on the carbon nanofibers as novel adsorbent for the extraction of polycyclic aromatic hydrocarbons from environmental water samples.

PubMed

Rezvani-Eivari, Mostafa; Amiri, Amirhassan; Baghayeri, Mehdi; Ghaemi, Ferial

2016-09-23

The application of magnetized graphene (G) layers synthesized on the carbon nanofibers (CNFs) (m-G/CNF) was investigated as novel adsorbent for the magnetic solid-phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs) in water samples followed by gas chromatography-flame ionization detector (GC-FID). Six important parameters, affecting the extraction efficiency of PAHs, including: amount of adsorbent, adsorption and desorption times, type and volume of the eluent solvent and salt content of the sample were evaluated. The optimum extraction conditions were obtained as: 5min for extraction time, 20mg for sorbent amount, dichloromethane as desorption solvent, 1mL for desorption solvent volume, 5min for desorption time and 15% (w/v) for NaCl concentration. Good performance data were obtained at the optimized conditions. The calibration curves were linear over the concentration ranges from 0.012 to 100ngmL(-1) with correlation coefficients (r) between 0.9950 and 0.9967 for all the analytes. The limits of detection (LODs, S/N=3) of the proposed method for the studied PAHs were 0.004-0.03ngmL(-1). The relative standard deviations (RSDs) for five replicates at two concentration levels (0.1 and 50ngmL(-1)) of PAHs were ranged from 3.4 to 5.7%. Appropriate relative recovery values, in the range of 95.5-99.9%, were also obtained for the real water sample analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Stir bar sorptive extraction combined with high performance liquid chromatography-ultraviolet/inductively coupled plasma mass spectrometry for analysis of thyroxine in urine samples.

PubMed

Fan, Wenying; Mao, Xiangju; He, Man; Chen, Beibei; Hu, Bin

2013-11-29

tIn this work, polyethyleneglycol (PEG)/hydroxyl polydimethylsiloxane (OH-PDMS)/γ -mercaptopropyltrimethoxysilane (γ -MPTS) coated stir bar was prepared by sol–gel process and its extraction performance for the extraction of amphoteric thyroxines (3,3',5,5'-tetraiodothyronin, T(4); 3,3',5-triiodothyronine, T(3); reversed-3,3',5-triiodothyronine, rT(3)) and their metabolite (3,5-diiodothyronine,T2) was studied. The preparation reproducibility of PEG/OH-PDMS/γ -MPTS coated stir bar was investigated, and the relative standard deviations (RSDs) in the same batch and among different batches were 3.3–14.3% (n = 5) and 7.7–16.6% (n = 3), respectively. The prepared PEG/OH-PDMS/γ -MPTS coated stir bar could be reused for more than 20 times. Based on this fact, a novel method of stir bar sorptive extraction (SBSE) combined with high performance liquid chromatography (HPLC)-ultraviolet (UV)and HPLC-inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of target thyroxinesin human urine samples was developed. The influencing factors of SBSE, such as sample pH, extraction time, stirring rate, salt effect, desorption solution and desorption time, were studied in detail, and the analytical performance of the proposed method was evaluated under the optimized conditions. The enrichment factors (EFs) of the developed method for four target thyroxines were in the range of 14.9–70.4(theoretical enrichment factor was 100). The RSDs were ranging from 4.0% to 13.8% for SBSE-HPLC-UV (c = 25 μg/L, n = 6) and from 3.7% to 6.1% for SBSE-HPLC-ICP-MS (c = 0.5 μg/L, n = 5). The linear range obtained by SBSE-HPLC-UV was 2–500 μg/L for T(2)and 5–500 μg/L for rT3, T(3)and T(4), with correlation coefficients (r) ranging from 0.9957 to 0.9998, respectively, while the linear range obtained by SBSE-HPLC-ICP-MS was 0.05–500 μg/L for T(2) and rT(3), 0.10–200 μg/L for T(3) and 0.05–200 μg/L for T(4)with r ranging from 0.9979 to 0.9998, respectively. The limits of detection (LODs) for the target thyroxines were 0.60–2.20 μg/L for SBSE-HPLC-UV and 0.0071–0.0355 μg/L SBSE-HPLC-ICP-MS, respectively. The developed method was applied for the determination of target thyroxines in urine samples, and the recovery for the spiking samples obtained by SBSE-HPLC-UV was in the range of 81.6–137.6% for human urine,while the recovery for the spiking urine samples obtained by SBSE-HPLC-ICP-MS were in the range of 72.0–121.5%.

Two-step liquid phase microextraction combined with capillary electrophoresis: a new approach to simultaneous determination of basic and zwitterionic compounds.

PubMed

Nojavan, Saeed; Moharami, Arezoo; Fakhari, Ali Reza

2012-08-01

In this work, two-step hollow fiber-based liquid-phase microextraction procedure was evaluated for extraction of the zwitterionic cetirizine (CTZ) and basic hydroxyzine (HZ) in human plasma. In the first step of extraction, the pH of sample was adjusted at 5.0 in order to promote liquid-phase microextraction of the zwitterionic CTZ. In the second step, the pH of sample was increased up to 11.0 for extraction of basic HZ. In this procedure, the extraction times for the first and the second steps were 30 and 20 min, respectively. Owing to the high ratio between the volumes of donor phase and acceptor phase, CTZ and HZ were enriched by factors of 280 and 355, respectively. The linearity of the analytical method was investigated for both compounds in the range of 10-500 ng mL(-1) (R(2) > 0.999). Limit of quantification (S/N = 10) for CTZ and HZ was 10 ng mL(-1) , while the limit of detection was 3 ng mL(-1) for both compounds at a signal to noise ratio of 3:1. Intraday and interday relative standard deviations (RSDs, n = 6) were in the range of 6.5-16.2%. This procedure enabled CTZ and HZ to be analyzed simultaneously by capillary electrophoresis. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Determination of biurea in flour and its products by liquid chromatography-tandem mass spectrometry].

PubMed

Wang, Ya; Wang, Junsu; Xiang, Lu; Xi, Cunxian; Chen, Dongdong; Peng, Tao; Wang, Guomin; Mu, Zhaode

2014-05-01

A novel method was established for the determination and identification of biurea in flour and its products using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The biurea was extracted with water and oxidized to azodicarbonamide by potassium permanganate. The azodicarbonamide was then derivatized using sodium p-toluene sulfinate solution. The separation was performed on a Shimpak XR-ODS II column (150 mm x 2.0 mm, 2.2 microm) using the mobile phase composed of acetonitrile and 2 mmol/L ammonium acetate aqueous solution (containing 0.2% (v/v) formic acid) with a gradient elution program. Tandem mass spectrometric detection was performed in multiple reaction monitoring (MRM) scan mode with a positive electrospray ionization (ESI(+)) source. The method used stable isotope internal standard quantitation. The calibration curve showed good linearity over the range of 1-20 000 microg/kg (R2 = 0.999 9). The limit of quantification was 5 microg/kg for biurea spiked in flour and its products. At the spiking levels of 5.0, 10.0 and 50.0 microg/kg in different matrices, the average recovery o biurea was 78.3%-108.0% with the relative standard deviations (RSDs) < or = 5.73%. The method developed is novel, reliable and sensitive with wide linear range, and can be used to determine the biurea in flour and its products.

[Simultaneous determination of five synthetic sweeteners in food by solid phase extraction-high performance liquid chromatography-evaporative light scattering detection].

PubMed

Liu, Fang; Wang, Yan; Wang, Yuhong; Zhou, Junyi; Yan, Chao

2012-03-01

A high performance liquid chromatographic method with evaporative light scattering detection (HPLC-ELSD) was developed for the simultaneous determination of five synthetic sweeteners (acesulfame-K, saccharin sodium, sodium cyclamate, sucralose and aspartame) in food. The sweeteners were extracted by 0.1% (v/v) formic acid buffer solution. The extract of sample was cleaned up and concentrated with solid phase extraction (SPE) cartridge. Then the sweeteners were separated on a C18 column (3 microm) using 0.1% (v/v) formic acid buffer (adjusted to pH = 3.5 with aqueous ammonia solution)-methanol (61: 39, v/v) as mobile phase, and finally detected by ELSD. The results showed that the reasonable linearity was achieved for all the analytes over the range of 30 - 1000 mg/L with the correlation coefficients (r) greater than 0.997. The recoveries for the five sweeteners ranged from 85.6% to 109.0% at three spiked concentrations with the relative standard deviations (RSDs) lower than 4.0%. The limits of detection (LODs, S/N = 3) were 2.5 mg/L for both acesulfame-K and sucralose, 3 mg/L for saccharin sodium, 10 mg/L for sodium cyclamate, and 5 mg/L for aspartame. The method is simple, sensitive and low cost, and has been successfully applied to the simultaneous determination of the five synthetic sweeteners in food.

[Determination of 23 antibiotics and 3 β-agonists in livestock drinking water by ultra performance liquid chromatography-tandem mass spectrometry coupled with solid-phase extraction].

PubMed

Shi, Ao

2016-02-01

A method has been developed for the simultaneous determination of 23 antibiotics (four categories) and 3 β-agonists in livestock drinking water using solid-phase extraction and ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI MS/MS). The samples were adjusted pH to 5. 0, added Na2EDTA, enriched and cleaned-up by an HLB solid-phase extraction cartridge. The target compounds were confirmed and quantified by UPLC-ESI MS/MS with external standard method for the anti- biotics and internal standard method for the β-agonists. The recoveries were assessed by using lab tap water as matrix. The average recoveries of the 23 antibiotics and the 3 β-agonists were in the range of 50. 7%-104. 6% and the relative standard deviations (RSDs) were 2. 6%-8. 8% (n= 3). Under the optimal conditions, the calibration curves of the 23 antibiotics and the 3 β-agonists showed good linearity with the correlation coefficients better than 0. 994. The limits of detection (LODs, S/N≥3) ranged from 0. 01-0. 20 ng/L. The developed method was applied to analyze the livestock drinking waters in 36 Beijing intensive livestock farms. The results showed that some antibiotics were detected.

Magnetic solid-phase extraction of non-steroidal anti-inflammatory drugs from environmental water samples using polyamidoamine dendrimer functionalized with magnetite nanoparticles as a sorbent.

PubMed

Alinezhad, Heshmatollah; Amiri, Amirhassan; Tarahomi, Mehrasa; Maleki, Behrooz

2018-06-01

A novel polyamidoamine dendrimer functionalized with Fe 3 O 4 nanoparticles (Fe 3 O 4 @PAMAM) had been fabricated and used as magnetic solid-phase extraction (MSPE) adsorbent. The Fe 3 O 4 @PAMAM nanocomposites were characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron spectroscopy, elemental analytical, and thermal gravimetric analysis. The MSPE method coupled with high-performance liquid chromatography with an ultraviolet detection system was applied for the separation/analysis of non-steroidal anti-inflammatory drugs (NSAIDs). Major parameters affecting the extraction efficiency of the selected drugs were optimized. Under optimal conditions, the enrichment factors for the proposed method were 701835. The linear range, limit of detection, correlation coefficient (r), and relative standard deviation (RSD) were found to be 0.15-500 ng mL -1 , 0.050.08 ng mL -1 , 0.99320.9967, and 4.5-7.0% (n = 5, 0.2, 10 and 300 ng mL -1 ), respectively. The method was successfully applied to the determination of NSAIDs in the real water samples. The recoveries of spiked water samples were in the range of 93.6-98.9% with RSDs varying from 6.1% to 9.0%, showing the good accuracy of the method. Copyright © 2018 Elsevier B.V. All rights reserved.

Direct screening of ground water samples for fuel oxygenates by headspace liquid phase microextraction-gas chromatography.

PubMed

Kaykhaii, Massoud; Mirbaloochzahi, Mohammad Reza

2008-12-01

The applicability of the headspace liquid phase microextraction and gas chromatography (HS-LPME/GC) for the expeditious and reliable screening of 68 well water samples for selected fuel oxygenates compounds, viz. methyl tertiary-butyl ether (MTBE), tertiary-amyl methyl ether (TAME), ethyl tertiary-butyl ether (ETBE) and n-butyl ethyl ether (n-BEE) has been evaluated. The method used 3 microl of 1:1 benzyl alcohol/1-octanol as extraction solvent, 20 min extraction time with stirring at 1,250 rpm, at 20 degrees C and salt addition of a mixture of 0.3 g ml(-1) sodium sulphate/0.1 g ml(-1) sodium chloride. The enrichment factors of this method were from 171 to 571. Limits of detection were in the range of 77-110 ng l(-1). The relative standard deviations (RSDs) at 0.05, 0.50 and 10.0 mg l(-1) of spiking levels were in the range of 1.28-6.80% with recoveries between 96.2 and 106.0%. Sixty-eight groundwater wells that were located near different gasoline reservoirs in eight largest cities of the Sistan and Balouchestan province were screened by the method. Eight contaminated wells were identified contained MTBE at levels between 0.3 and 1.7 mg l(-1). In all cases, other target analytes were at low concentrations or not detected.

[Determination of organotin compounds in textile auxiliaries by gas chromatography-mass spectrometry].

PubMed

Li, Yanming; Hu, Yongjie; Liu, Jinhua; Guo, Yuliang; Wang, Guiqin

2011-04-01

A gas chromatography-mass spectrometry (GC-MS) method has been developed for the determination of dibutyltin (DBT), tributyltin (TBT) and triphenyltin (TPhT) in textile auxiliaries. The sample was first extracted with n-hexane in acetate buffer solution (pH 4.0) under ultrasonication (for hydrophobic sample) or oscillation extraction (for hydrophilic sample) and then derivatized with sodium tetraethylborate in tetrahydrofuran. The derivative was determined by GC-MS in selected ion monitoring (SIM) mode. The separation and quantification were achieved using a Rxi-5 ms silica capillary column (30 m x 0.25 mm x 0.25 microm). The linear ranges were 0.1-8.0 mg/L for both DBT and TBT, and 0.1-4.0 mg/L for TPhT. There were good linear relationships between the peak area and concentration in the linear ranges and the correlation coefficients (r2) were 0.9994-0.9998. The detection limits (LOD) were from 0.003 mg/L to 0.005 mg/L. The average recoveries of these organotin compounds at the three spiked levels of 4.0, 10.0 and 40.0 mg/kg were 92.6%-108.0% with the relative standard deviations (RSDs) of 2.5%-10.2%. The method is simple and accurate for simultaneous analysis of the DBT, TBT and TPhT in textile auxiliaries.

Carbon-Based Fe3O4 Nanocomposites Derived from Waste Pomelo Peels for Magnetic Solid-Phase Extraction of 11 Triazole Fungicides in Fruit Samples

PubMed Central

Ren, Keyu; Zhang, Wenlin; Cao, Shurui; Wang, Guomin; Zhou, Zhiqin

2018-01-01

Carbon-based Fe3O4 nanocomposites (C/Fe3O4 NCs) were synthesized by a simple one-step hydrothermal method using waste pomelo peels as the carbon precursors. The characterization results showed that they had good structures and physicochemical properties. The prepared C/Fe3O4 NCs could be applied as excellent and recyclable adsorbents for magnetic solid phase extraction (MSPE) of 11 triazole fungicides in fruit samples. In the MSPE procedure, several parameters including the amount of adsorbents, extraction time, the type and volume of desorption solvent, and desorption time were optimized in detail. Under the optimized conditions, the good linearity (R2 > 0.9916), the limits of detection (LOD), and quantification (LOQ) were obtained in the range of 1–100, 0.12–0.55, and 0.39–1.85 μg/kg for 11 pesticides, respectively. Lastly, the proposed MSPE method was successfully applied to analyze triazole fungicides in real apple, pear, orange, peach, and banana samples with recoveries in the range of 82.1% to 109.9% and relative standard deviations (RSDs) below 8.4%. Therefore, the C/Fe3O4 NCs based MSPE method has a great potential for isolating and pre-concentrating trace levels of triazole fungicides in fruits. PMID:29734765

[Determination of thyreostats in bovine urine using ultra-high performance liquid chromatography-tandem mass spectrometry].

PubMed

Lech, Rodziewicz; Jolanta, MasŁOwiecka; Anna, Sadowska; Halina, Car

2017-10-08

Five thyreostats (TSs), namely tapazole, thiouracil, methylthiouracil, propylthiouracil, and phenylthiouracil, were determined in bovine urine using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in positive electrospray ionization mode. Extraction and clean-up were achieved using a ChemElut cartridge with tert -butyl methyl ether, without a derivatization step. Separation was achieved on an Acquity UPLC SS T3 column. The mobile phase was acetonitrile and water containing 0.2% (v/v) formic acid. The mass spectrometer was operated in multiple reaction monitoring mode. Urine samples were spiked with TS solution at levels corresponding to 5, 10, 15, and 20 μg/L. The accuracy (internal standard corrected) ranged from 92% to 107%, with a repeatability precision (relative standard deviation, RSD) less than 15% for all five analytes. The RSDs within-laboratory reproducibility was less than 26%. The decision limits (CCα) and detection capabilities (CCβ) were obtained from a calibration curve and were in the ranges of 3.1-6.1 μg/L and 4.0-7.4 μg/L, respectively. The CCα and CCβ values were below the recommended concentration, which was set at 10 μg/L. The results show that the described method is suitable for the direct detection of TSs in bovine urine. This method can also be used to determine TSs in porcine urine.

[Determination of six plant growth regulator residues in strawberry by liquid chromatography-quadrupole time of flight mass spectrometry].

PubMed

Liu, Jingjing; Gong, Ping; Zhang, Xiaomei; Wang, Jianhua; Wang, Jingtang

2012-10-01

A novel method was established for the determination of six plant growth regulators (PGRs), 2,4-dichlorophenoxy acetic (2,4-D), 4-chlorophenoxy-acetic acid (CAP), 4-(3-indolyl)-butyric acid (BAA), forchlorfenuron (CPPU), abscisic acid (ABA) and trans-zeatin (ZT) in strawberry using liquid chromatography-quadrupole-time of flight mass spectrometry (LC-Q TOF MS). The Quick, Easy, Cheap, Effective, Rugged and Safe method (QuEChERS) has been validated for the extraction. In this QuEChERS method, the sample was extracted by acetonitrile and cleaned up with C18 adsorbent. The extract was measured directly by LC-Q TOF MS with electrospray ionization in negative mode. The compounds were separated on an Eclipse XDB-C8 column (150 mm x 4.6 mm, 5 microm) with acetonitrile-5 mmol/L ammonium acetate-0. 1% formic acid as mobile phase under gradient elution. The confirmatory analysis was carried out by determining the accurate masses of all compounds and fragment ions upon Target MS/MS. The limits of detection (LODs) were between 1 microg/kg and 5 microg/kg. The linear range was 0.005-1.0 mg/L for each analyte. The recoveries ranged from 87% to 107% with the relative standard deviations (RSDs) less than 10% (n = 6). The method was proved to be simple and accurate.

Simultaneous determination of bisphenols and alkylphenols in water by solid phase extraction and ultra performance liquid chromatography-tandem mass spectrometry.

PubMed

Shan, Xiao Mei; Shen, Deng Hui; Wang, Bing Shuang; Lu, Bei Bei; Huang, Fa Yuan

2014-06-01

To establish an analytical method for determination of four bisphenols (BPA, BPB, BPF, and BPS) and two alkylphenols (4-n-OP, 4-n-NP) in water by ultra performance liquid chromatography- tandem mass spectrometry (UPLC/MS/MS). The water samples were extracted and condensed with solid-phase extraction (SPE) using C18 cartridges and eluted by acetonitrile. Separation was carried out with Acquity BEH C8 column and detection were performed by UPLC/MS/MS. Quantification was calculated by using the internal standard BPA-d16 and 4-n-NP-d8. The linear correlation coefficients of these compounds in the range of 1.0-100.0 μg/L were all over 0.999. The minimum detectable concentrations were 0.75-1.0 ng/L, and the recoveries ranged from 87.0% to 106.9%. Relative standard deviations (RSDs) were between 1.26% and 3.67%. Applying this method to detect the source water of Chaohu Lake and drinking water of Hefei, six target compounds were detected in different levels. This method is simple with high sensitivity and selectivity, could be suitable for the determination of these compounds in source and drinking water. Copyright © 2014 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

[Determination of four insecticide residues in honey and royal jelly by gas chromatography-negative chemical ionization mass spectrometry].

PubMed

Xia, Guanghui; Shen, Weijian; Yu, Keyao; Wu, Bin; Zhang, Rui; Shen, Chongyu; Zhao, Zengyun; Bian, Xiaohong; Xu, Jiyang

2014-07-01

A method was developed for the determination of four insecticide residues in honey and royal jelly by gas chromatography-negative chemical ionization mass spectrometry (GC-NCI/MS). The honey and royal jelly samples were treated with different preparation methods as the result of the different components. The honey sample was extracted with ethyl acetate and cleaned up with primary second amine, and the royal jelly sample was extracted with acetonitrile-water (1:1, v/v), and cleaned up with a C18 solid-phase extraction column. Finally, the extracts of the honey and royal jelly were analyzed by GC-NCI/MS in selected ion monitoring (SIM) mode separately. External standard calibration method was used for quantification. The linearities of calibration curves of the four insecticides were good with the correlation coefficients greater than 0.99 in the range of 50-500 microg/L. The limits of the detection (LODs) of the four insecticides were in the range of 0.12- 5.0 microg/kg, and the limits of the quantification (LOQs) were in the range of 0.40-16.5 microg/kg. The recoveries of the four insecticides spiked in honey and royal jelly at three spiked levels (10, 15 and 20 microg/kg) were in the range of 78.2 -110.0%, and the relative standard deviations (RSDs) were all below 14%. The sensitivity and selectivity of this method were good with no interfering peaks. The proposed method is simple quick and effective to analyze the four insecticide residues in honey and royal jelly.

Determination of organophosphorus flame retardants in fish by pressurized liquid extraction using aqueous solutions and solid-phase microextraction coupled with gas chromatography-flame photometric detector.

PubMed

Gao, Zhanqi; Deng, Yuehua; Yuan, Wenting; He, Huan; Yang, Shaogui; Sun, Cheng

2014-10-31

A novel method was developed for the determination of organophosphorus flame retardants (PFRs) in fish. The method consists of a combination of pressurized liquid extraction (PLE) using aqueous solutions and solid-phase microextraction (SPME), followed by gas chromatography-flame photometric detector (GC-FPD). The experimental parameters that influenced extraction efficiency were systematically evaluated. The optimal responses were observed by extracting 1g of fish meat with the solution of water:acetonitrile (90:10, v/v) at 150°C for 5min and acid-washed silica gel used as lipid sorbent. The obtained extract was then analyzed by SPME coupled with GC-FPD without any additional clean-up steps. Under the optimal conditions, the proposed procedure showed a wide linear range (0.90-5000ngg(-1)) obtained by analyzing the spiked fish samples with increasing concentrations of PFRs and correlation coefficient (R) ranged from 0.9900 to 0.9992. The detection limits (S/N=3) were in the range of 0.010-0.208ngg(-1) with standard deviations (RSDs) ranging from 2.0% to 9.0%. The intra-day and inter-day variations were less than 9.0% and 7.8%, respectively. The proposed method was successfully applied to the determination of PFRs in real fish samples with recoveries varying from 79.8% to 107.3%. The results demonstrate that the proposed method is highly effective for analyzing PFRs in fish samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluation of quality-control data collected by the U.S. Geological Survey for routine water-quality activities at the Idaho National Laboratory and vicinity, southeastern Idaho, 2002-08

USGS Publications Warehouse

Rattray, Gordon W.

2014-01-01

Quality-control (QC) samples were collected from 2002 through 2008 by the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, to ensure data robustness by documenting the variability and bias of water-quality data collected at surface-water and groundwater sites at and near the Idaho National Laboratory. QC samples consisted of 139 replicates and 22 blanks (approximately 11 percent of the number of environmental samples collected). Measurements from replicates were used to estimate variability (from field and laboratory procedures and sample heterogeneity), as reproducibility and reliability, of water-quality measurements of radiochemical, inorganic, and organic constituents. Measurements from blanks were used to estimate the potential contamination bias of selected radiochemical and inorganic constituents in water-quality samples, with an emphasis on identifying any cross contamination of samples collected with portable sampling equipment. The reproducibility of water-quality measurements was estimated with calculations of normalized absolute difference for radiochemical constituents and relative standard deviation (RSD) for inorganic and organic constituents. The reliability of water-quality measurements was estimated with pooled RSDs for all constituents. Reproducibility was acceptable for all constituents except dissolved aluminum and total organic carbon. Pooled RSDs were equal to or less than 14 percent for all constituents except for total organic carbon, which had pooled RSDs of 70 percent for the low concentration range and 4.4 percent for the high concentration range. Source-solution and equipment blanks were measured for concentrations of tritium, strontium-90, cesium-137, sodium, chloride, sulfate, and dissolved chromium. Field blanks were measured for the concentration of iodide. No detectable concentrations were measured from the blanks except for strontium-90 in one source solution and one equipment blank collected in September and October 2004, respectively. The detectable concentrations of strontium-90 in the blanks probably were from a small source of strontium-90 contamination or large measurement variability, or both. Order statistics and the binomial probability distribution were used to estimate the magnitude and extent of any potential contamination bias of tritium, strontium-90, cesium-137, sodium, chloride, sulfate, dissolved chromium, and iodide in water-quality samples. These statistical methods indicated that, with (1) 87 percent confidence, contamination bias of cesium-137 and sodium in 60 percent of water-quality samples was less than the minimum detectable concentration or reporting level; (2) 92‒94 percent confidence, contamination bias of tritium, strontium-90, chloride, sulfate, and dissolved chromium in 70 percent of water-quality samples was less than the minimum detectable concentration or reporting level; and (3) 75 percent confidence, contamination bias of iodide in 50 percent of water-quality samples was less than the reporting level for iodide. These results support the conclusion that contamination bias of water-quality samples from sample processing, storage, shipping, and analysis was insignificant and that cross-contamination of perched groundwater samples collected with bailers during 2002–08 was insignificant.

Comparative chromatography-mass spectrometry studies on the antiretroviral drug nevirapine-analytical performance characteristics in human plasma determination.

PubMed

Sichilongo, Kwenga; Chinyama, Mompati; Massele, Amos; Vento, Sandro

2014-01-15

A contrast between the analytical performance characteristics using gas chromatography-mass spectrometry (GC-MS) liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-ultraviolet (LC-UV) detection for the determination of the antiretroviral drug (ARV) nevirapine (NVP) in fortified human plasma after QuEChERS extraction has been made. Analytical performance characteristics, i.e. linearities, instrument detection limits (IDLs), limits of quantitation (LOQs), method detection limits (MDLs), % mean recoveries and the corresponding relative standard deviations (%RSDs) were estimated using techniques above. Using GC-MS, the correlation coefficients (r(2)) were ≥0.990, which were deemed acceptable linearities. The MDLs ranged between 11.1-29.8μg/L and 13.7-36.0μg/L using helium and hydrogen carrier gases respectively. The LOQs ranged between 16.5-66.7μg/L and 28.4-98.7μg/L using helium and hydrogen carrier gases respectively with a % mean recovery of 83% and %RSD of 4.6%. Using LC-MS and LC-UV, the correlation coefficients (r(2)) were ≥0.990. The MDLs were ranged between 3.14 and 47.1μg/L. The LOQs ranged between 2.85 and 90.0μg/L respectively. The MDLs using GC-MS, LC-MS and LC-UV were below the therapeutic range for NVP in human plasma is considered to be between 2300μg/L (Cmin) and 8000μg/L (Cmax). This study also demonstrated that helium can be substituted with hydrogen which is relatively cheaper and easily obtainable even by use of a generator. Copyright © 2013 Elsevier B.V. All rights reserved.

Development of a Efficient and Sensitive Dispersive Liquid–Liquid Microextraction Technique for Extraction and Preconcentration of 10 β2-Agonists in Animal Urine

PubMed Central

2015-01-01

Dispersive liquid–liquid microextraction (DLLME) coupled with ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) was developed for the extraction and determination of 10 β2-agonists in animal urine. Some experimental parameters, such as the type and volume of the extraction solvent, the concentration of the dispersant, the salt concentration, the pH value of the sample solution, the extraction time and the speed of centrifugation, were investigated and optimized. Under the optimized conditions, a good enrichment factors (4.8 to 32.3) were obtained for the extraction. The enrichment factor show that the concentration rate of DLLME is significantly higher than other pretreatment methods, and the detection sensitivity has been greatly improved. The calibration curves were linear, the correlation coefficient ranged from 0.9928 to 0.9999 for the concentration range of 0.05 to 50 ngmL-1 and 0.1 to 50 ngmL-1, and the relative standard deviations (RSDs, n = 15, intra and inter-day precision) at a concentration of 5 ngmL-1 were in the range of 1.8 to 14.6%. The limits of detection (LODs) for the 10 β2-agonists, based on a signal-to-noise ratio (S/N) of 3, were in the range of 0.01 to 0.03 ngmL-1. The proposed method was used to identify β2-agonists in three types of animal urine (swine, cattle, sheep), and the relative recoveries from each matrix were in the range of 89.2 to 106.8%, 90.0 to 109.8% and 89.2 to 107.2%, respectively. PMID:26348922

Dispersive liquid-liquid microextraction method based on solidification of floating organic droplet for the determination of thiamphenicol and florfenicol in environmental water samples.

PubMed

Peng, Guilong; He, Qiang; Al-Hamadani, Sulala M Z F; Zhou, Guangming; Liu, Mengzi; Zhu, Hui; Chen, Junhua

2015-05-01

Dispersive liquid-liquid microextraction with solidification of a floating organic droplet (DLLME-SFO) followed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection was applied for the determination of thiamphenicol (TAP), florfenicol (FF) in water samples. 1-Undecanol was used as the extraction solvent which has lower density than water, low toxicity, and low melting point (19°C). A mixture of 800mL acetone (disperser solvent) and 80µL of 1-undecanol (extraction solvent) was injected into 20mL of aqueous solution. After 5min, 0.6g of NaCl was added and the sample vial was shaken. After 5min, the sample was centrifuged at 3500rpm for 3min, and then placed in an ice bath. When the extraction solvent floating on the aqueous solution had solidified, it was transferred into another conical vial where it was melted quickly at room temperature, and was diluted with methanol to 1mL, and analyzed by HPLC-UV detection. Parameters influencing the extraction efficiency were thoroughly examined and optimized. The extraction recoveries (ER) and the enrichment factors (EF) ranged from 67% to 72% and 223 to 241, respectively. The limits of detection (LODs) (S/N=3) were 0.33 and 0.56µgL(-1) for TAP and FF, respectively. Linear dynamic range (LDR) was in the range of 1.0-550µgL(-1) for TAP and 1.5-700µgL(-1) for FF, the relative standard deviations (RSDs) were in the range of 2.6-3.5% and the recoveries of spiked samples ranged from 94% to 106%. Copyright © 2015 Elsevier Inc. All rights reserved.

Rapid analysis of chlorinated anilines in environmental water samples using ultrasound assisted emulsification microextraction with solidification of floating organic droplet followed by HPLC-UV detection.

PubMed

Ramkumar, Abilasha; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

2012-08-15

The present study demonstrates a simple, rapid and efficient method for the determination of chlorinated anilines (CAs) in environmental water samples using ultrasonication assisted emulsification microextraction technique based on solidification of floating organic droplet (USAEME-SFO) coupled with high performance liquid chromatography-ultraviolet (HPLC-UV) detection. In this extraction method, 1-dodecanol was used as extraction solvent which is of lower density than water, low toxicity, low volatility, and low melting point (24 °C). After the USAEME, extraction solvent could be collected easily by keeping the extraction tube in ice bath for 2 min and the solidified organic droplet was scooped out using a spatula and transferred to another glass vial and allowed to thaw. Then, 10 μL of extraction solvent was diluted with mobile phase (1:1) and taken for HPLC-UV analysis. Parameters influencing the extraction efficiency, such as the kind and volume of extraction solvent, volume of sample, ultrasonication time, pH and salt concentration were thoroughly examined and optimized. Under the optimal conditions, the method showed good linearity in the concentration range of 0.05-500 ng mL(-1) with correlation coefficients ranging from 0.9948 to 0.9957 for the three target CAs. The limit of detection based on signal to noise ratio of 3 ranged from 0.01 to 0.1 ng mL(-1). The relative standard deviations (RSDs) varied from 2.1 to 6.1% (n=3) and the enrichment factors ranged from 44 to 124. The proposed method has also been successfully applied to analyze real water samples and the relative recoveries of environmental water samples ranged from 81.1 to 116.9%. Copyright © 2012 Elsevier B.V. All rights reserved.

AN INVESTIGATION OF REMOTE SENSING DEVICES FOR CHEMICAL CHARACTERIZATION OF MOTOR VEHICLE EXHAUST

EPA Science Inventory

The report summarizes results of tests to (1) evaluate the accuracy and precision of two different remote sensing devices (RSDs) for measuring carbon monoxide (CO), hydrocarbons (HCs), and nitric oxide (NO) and (2) evaluate the capabilities of three RSDs for characterizing fleet ...

Evaluation of potentially nonlethal sampling methods for monitoring mercury concentrations in smallmouth bass (Micropterus dolomieu)

USGS Publications Warehouse

Schmitt, C.J.; Brumbaugh, W.G.

2007-01-01

We evaluated three potentially nonlethal alternatives to fillet sampling for the determination of mercury (Hg) concentrations in smallmouth bass (Micropterus dolomieu). Fish (n = 62, 226-464 mm total length) from six sites in southern Missouri were captured by electrofishing. Blood samples (1 mL) from each fish were obtained by caudal veinipuncture with a heparinized needle and syringe. Biopsy needle (10 mm x 14 gauge; three cuts per fish; 10-20 mg total dry weight) and biopsy punch (7 mm x 5 mm in diameter, one plug per fish, 30-50 mg dry weight) samples were obtained from the area beneath the dorsal fin. Fillet samples were obtained from the opposite side of the fish. All samples were freeze-dried and analyzed for total Hg by combustion amalgamation atomic absorption spectrophotometry. Mean relative standard deviations (RSDs) of triplicate samples were similar for all four methods (2.2-2.4%), but the range of RSDs was greater for blood (0.4-5.5%) than for the muscle methods (1.8-4.0%). Total Hg concentrations in muscle were 0.0200-0.8809 ??g/g wet weight; concentrations in plug, needle, and fillet samples from each fish were nearly identical. Blood Hg concentrations were 0.0006-0.0812 ??g/mL and were highly correlated with muscle concentrations; linear regressions between log-transformed blood and fillet Hg concentrations were linear and statistically significant (p < 0.01), and explained 91-93% of the total variation. Correlations between fillet Hg concentrations and fish size and age were weak; together they explained ???37% of the total variation, and the relations differed among sites. Overall, any of the alternative methods could provide satisfactory estimates of fillet Hg in smallmouth bass; however, both blood and plug sampling with disposable instruments were easier to perform than needle sampling. The biopsy needle was the most difficult to use, especially on smaller fish, and its relative expense necessitates reuse and, consequently, thorough cleaning between fish to prevent cross-contamination. ?? 2007 Springer Science+Business Media, LLC.

Analysis of polybrominated diphenyl ethers and emerging halogenated and organophosphate flame retardants in human hair and nails.

PubMed

Liu, Liang-Ying; Salamova, Amina; He, Ka; Hites, Ronald A

2015-08-07

A method for the digestion, extraction, fractionation, and analysis of three classes of flame retardants, including 36 polybrominated diphenyl ethers (PBDEs), 9 halogenated alternative flame retardants (AFRs), and 12 organophosphate esters (OPEs) in human hair and nail samples was developed. The method employed HNO3/H2O2 digestion, liquid-liquid extraction with (4:1 vol) hexane:dichloromethane, fractionation on a 6g column of 2.5% water deactivated Florisil, and analysis by gas chromatographic mass spectrometry. The accuracy and precision of the method was validated using spiked samples of 6 replicates for both hair and nail samples. The method validation results showed good accuracy and precision for all PBDEs except BDE-209, all AFRs except hexabromobenzene (HBB), and all of the 12 OPEs, with average recovery efficiencies>90% and relative standard deviations (RSDs)<10%. The average recovery efficiencies for HBB were between 60% and 86%, with RSDs<10%. BDE-209 had recovery efficiencies of 64% (RSD, 13%) for hair and 71% (RSD, 10%) for nail. This method was applied to analyze 5 human hair and 5 fingernail samples from the general student population at Indiana University Bloomington campus. BDE-47 and BDE-99 were the predominant PBDEs detected in both hair and nail samples, with a concentration range of 11-620 and 4.6-780ng/g (dry weight) in hair and 7.3-43 and 2.1-11ng/g in nails, respectively. Di-(2-ethylhexyl)-tetrabromophthalate (TBPH) and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (TBB) were detected in all the samples, with concentrations of 20-240 and 11-350ng/g in hair and <17-80 and <9.2-71ng/g in nails, respectively. Among the 12 OPEs analyzed, tris(2-chloroethyl)phosphate (TCEP), tris(1-chloro-2-propyl)phosphate (TCIPP), tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), and triphenyl phosphate (TPHP) were most often detected. The concentrations of these OPEs (summed together) were 1100-3900 and 380-18,000ng/g in hair and nails, respectively. These levels exceed those of both the PBDEs and the AFRs. Copyright © 2015 Elsevier B.V. All rights reserved.

[Determination of 6 kinds of plant growth regulator in bean sprout by ultra high performance liquid chromatography-tandem mass spectrometry].

PubMed

Liu, Ping; Fan, Sai; Wu, Guohua; Zhao, Rong; Liu, Wei; Zhao, Xudong

2016-05-01

A method for the simultaneous determination of 6 plant growth regulator (PGR) residues in bean sprout was developed by ultra high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). 6-Benzylaminopurine, isopentennyladenine, 4-chlorophenoxyacetic acid, 4-fluorophenoxyacetic acid, indole-3- acetic acid and indole-3-butyric acid were concerned. Bean sprout samples were extracted by acetonitrile and QuEChERS extraction kit, purified by C18 powers. After centrifugation, the sample liquids was diluted 10 times by ultrapure water. The chromatographic analysis was carried out on an waters acquity UPLC BEH C18 column( 100 mm x 2.1 mm, 1.7 microm). The analyzer confirmed and quantified by mass spectrum of triple quadrupole in the multiple reaction monitoring (MRM) mode and quantified by matrix-matched external standard method. The calibration curves showed good linearity in each range with correlation coefficients greater than 0.998. 3 levels spiked recoveries were carried out using blank bean sprout extraction as substrate, the recoveries ranged from 84.2% to 107.5%, the relative standard deviations (RSDs) ranged from 3.08% to 12.71%. The qualitative limits of detections (S/N = 3) were 0.03-3.0 microg/kg and the quantitative limits(S/N = 10) were 0.1-10.0 microg/kg for the 6 PGRs. The method is simple and easy to operate, with less organic reagent, high sensitivity and good stability. It is suitable for the detection of 6 kinds of plant growth regulators in bean sprouts.

Analytical capabilities of high performance liquid chromatography - Atmospheric pressure photoionization - Orbitrap mass spectrometry (HPLC-APPI-Orbitrap-MS) for the trace determination of novel and emerging flame retardants in fish.

PubMed

Zacs, D; Bartkevics, V

2015-10-22

A new analytical method was established and validated for the analysis of 27 brominated flame retardants (BFRs), including so called "emerging" and "novel" BFRs (EBFRs and NBFRs) in fish samples. High performance liquid chromatography (HPLC) coupled to Orbitrap mass spectrometry (Orbitrap-MS) employing atmospheric pressure photoionization (APPI) interface operated in negative mode was used for the identification/quantitation of contaminants. HPLC-Orbitrap-MS analysis provided a fast separation of selected analytes within 14 min, thus demonstrating a high throughput processing of samples. The developed methodology was tested by intralaboratory validation in terms of recovery, repeatability, linear calibration ranges, instrumental and method limits of quantitation (i-LOQ and m-LOQ), and where possible, trueness was verified by analysis of certified reference materials (CRMs). Recoveries of analytes were between 80 and 119%, while the repeatability in terms of relative standard deviations (RSDs) was in the range from 1.2 to 15.5%. The measured values for both analyzed CRMs agreed with the provided consensus values, revealing the recovery of reference concentrations in 72-119% range. The elaborated method met the sensitivity criterion according to Commission Recommendation 2014/118/EU on monitoring of BFRs in food products for majority of the compounds. The concentrations of polybrominated diphenyl ethers (PBDEs) in real samples determined by HPLC-APPI-Orbitrap-MS method and validated gas chromatography-high-resolution mass spectrometry (GC-HRMS) method were found to be in a good agreement. Copyright © 2015 Elsevier B.V. All rights reserved.

[Influences of ion-suppressors on retention behaviors of nine food additives in reversed-phase high performance liquid chromatographic separation].

PubMed

Zhao, Yonggang; Chen, Xiaohong; Li, Xiaoping; Yao, Shanshan; Jin, Micong

2011-10-01

The influences of ion-suppressors on retention behaviors of nine food additives, i.e., acesulfame, saccharin, caffeine, aspartame, benzoic acid, sorbic acid, stevioside, dehydroacetic acid and neotame in reversed-phase high performance liquid chromatographic (RP-HPLC) separation were investigated. The organic modification effects of acids, i. e. , trifluoroacetic acid (TFA) and buffer salts, i. e. , TFA-ammonium acetate (AmAc) were studied emphatically. The relationships between retention factors of solutes and volume percentages of ion-suppressors in the mobile phase systems of acetonitrile-TFA aqueous solution and acetonitrile-TFA-AmAc aqueous solution were quantitatively established, separately. The separation of nine food additives was completed by a gradient elution with acetonitrile-TFA (0.01%, v/v)-AmAc (2. 5 mmol/L) aqueous solution as the mobile phases. An RP-HPLC method was established for the simultaneous determination of nine food additives in red wine. In the range of 10. 0 - 100. 0 mg/L, nine food additives showed good linearity with the correlation coefficients ( r2 ) larger than 0. 999 1. The limits of detection (LODs) were in the range of 0. 33 - 2. 36 mg/L and the limits of quantification (LOQs) were in the range of 1. 11 - 7. 80 mg/L. The spiked recoveries were between 87. 61% and 108. 4% with the relative standard deviations (RSDs) of 2. 2% -9. 4%. These results are of referential significance for the rapid establishment and accu- rate optimization of RP-HPLC separation for the simultaneous determination of food additives in other foods.

Simulation of radar reflectivity and surface measurements of rainfall

NASA Technical Reports Server (NTRS)

Chandrasekar, V.; Bringi, V. N.

1987-01-01

Raindrop size distributions (RSDs) are often estimated using surface raindrop sampling devices (e.g., disdrometers) or optical array (2D-PMS) probes. A number of authors have used these measured distributions to compute certain higher-order RSD moments that correspond to radar reflectivity, attenuation, optical extinction, etc. Scatter plots of these RSD moments versus disdrometer-measured rainrates are then used to deduce physical relationships between radar reflectivity, attenuation, etc., which are measured by independent instruments (e.g., radar), and rainrate. In this paper RSDs of the gamma form as well as radar reflectivity (via time series simulation) are simulated to study the correlation structure of radar estimates versus rainrate as opposed to RSD moment estimates versus rainrate. The parameters N0, D0 and m of a gamma distribution are varied over the range normally found in rainfall, as well as varying the device sampling volume. The simulations are used to explain some possible features related to discrepancies which can arise when radar rainfall measurements are compared with surface or aircraft-based sampling devices.

Pesticide Multiresidue Analysis in Cereal Grains Using Modified QuEChERS Method Combined with Automated Direct Sample Introduction GC-TOFMS and UPLC-MS/MS Techniques

USDA-ARS?s Scientific Manuscript database

The QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation method was modified to accommodate various cereal grain matrices (corn, oat, rice and wheat) and provide good analytical results (recoveries in the range of 70-120% and RSDs <20%) for the majority of the target pestici...

Targeting Biological Sensing with Commercial SERS Substrates

DTIC Science & Technology

2012-09-01

ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Army Research Laboratory ATTN: RDRL-SEE-E 2800 Powder Mill Road Adelphi, MD 20783-1197 8. PERFORMING...Pellegrino* *U.S. Army Research Laboratories, RDRL-SEE-E, 2800 Powder Mill Road, Adelphi, Maryland 20783 Department of Mechanical Engineering and...demonstrated typical RSDs ranging from 10-15% under drop and dry conditions. While these standard Klarite substrates do demonstrate a high

Comparison of solidification of floating drop and homogenous liquid-liquid microextractions for the extraction of two plasticizers from the water kept in PET-bottles.

PubMed

Yamini, Yadollah; Ghambarian, Mahnaz; Khalili-Zanjani, Mohammad Reza; Faraji, Mohammad; Shariati, Shahab

2009-09-01

Two approaches based on solidification of floating drop microextraction (SFDME) and homogenous liquid-liquid microextraction (HLLE) were compared for the extraction and preconcentration of di-(2-ethylhexyl) phthalate (DEHP) and di-(2-ethylhexyl) adipate (DEHA) from the mineral water samples. In SFDME, a floated drop of the mixture of acetophenone/1-undecanol (1:8) was exposed on the surface of the aqueous solution and extraction was permitted to occur. In HLLE, a homogenous ternary solvent system was used by water/methanol/chloroform and the phase separation phenomenon occurred by salt addition. Under the optimal conditions, the LODs for the two target plasticizers (DEHA and DEHP), obtained by SFDME-GC-FID and HLLE-GC-FID, were ranged from 0.03 to 0.01 microg/L and 0.02 to 0.01 microg/L, respectively. HLLE provided higher preconcentration factors (472.5- and 551.2-fold) within the shorter extraction time as well as better RSDs (4.5-6.9%). While, in SFDME, high preconcentration factors in the range of 162-198 and good RSDs in the range of 5.2-9.6% were obtained. Both methods were applied for the analysis of two plasticizers in different water samples and two target plasticizers were found in the bottled mineral water after the expiring time and the boiling water was exposed to a polyethylene vial.

[Determination of seven phenoxyacid herbicides in environmental water by high performance liquid chromatography coupled with three phase hollow fiber liquid phase microextraction].

PubMed

Peng, Xiaojun; Pang, Jinshan; Deng, Aihua

2011-12-01

A novel method for the simultaneous determination of seven phenoxyacid herbicides such as dicamba, fluroxypyr, 4-chlorophenoxyacetic acid (4-CPA), 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2, 4-dichlorophenoxyacetic acid (2,4-D), 2,4-dichlorophenoxybutyric acid (2,4-DB) and 4-(2-methyl-4-chlorophenoxy) butyric acid (MCPB) in environmental water by three phase hollow fiber liquid phase microextraction (HF-LPME) coupled with high performance liquid chromatography (HPLC) was developed. In order to optimize the experimental conditions, the orthogonal test has been used. The effects of extraction solvent, pH of the donor phase and acceptor phase, extraction time, stirring speed and salt concentration on the detection were investigated. The optimal experimental conditions were as follows: octanol as organic solvent, pH 3 of donor phase, pH 12 of acceptor phase, extraction time of 30 min, stirring speed of 400 r/min. The results showed that the proposed method provided a wide linear range for 7 phenoxyacid herbicides with correlation coefficients of 0.995 3 - 0.998 8. The detection limits ranged from 0.2 to 1.0 microg/L. The enrichment factors were in the range of 76.7 - 121. The recoveries were in the range of 68% - 104% and the relative standard deviations (RSDs) were less than 8.1% for the environmental water samples. The method has the advantages of sensitivity, simplicity, fastness and the use of very small amounts of organic solvent. The method can meet the requirements of the determination of trace phenoxyacid herbicides in the environmental water samples, and the study provided a useful method for the analysis of trace substances in water samples.

Determination and quantification of active phenolic compounds in pigeon pea leaves and its medicinal product using liquid chromatography–tandem mass spectrometry.

PubMed

Liu, Wei; Kong, Yu; Zu, Yuangang; Fu, Yujie; Luo, Meng; Zhang, Lin; Li, Ji

2010-07-09

A novel method using liquid chromatography coupled to electrospray ionization mass spectrometry (LC-ESI-MS) has been optimized and established for the qualitative and quantitative analysis of ten active phenolic compounds originating from the pigeon pea leaves and a medicinal product thereof (Tongluo Shenggu capsules). In the present study, the chromatographic separation was achieved by means of a HiQ Sil C18V reversed-phase column with a mobile phase consisting of methanol and 0.1% formic acid aqueous solution. Low-energy collision-induced dissociation tandem mass spectrometry (CID-MS/MS) using the selected reaction monitoring (SRM) analysis was employed for the detection of ten analytes which included six flavonoids, two isoflavonoids and two stilbenes. All calibration curves showed excellent coefficients of determination (r(2) ≥ 0.9937) within the range of tested concentrations. The intra- and inter-day variations were below 5.36% in terms of relative standard deviation (RSD). The recoveries were 95.08-104.98% with RSDs of 2.06-4.26% for spiked samples of pigeon pea leaves. The method developed was a rapid, efficient and accurate LC-MS/MS method for the detection of phenolic compounds, which can be applied for quality control of pigeon pea leaves and related medicinal products.

Simultaneous quantification of coumarins, flavonoids and limonoids in Fructus Citri Sarcodactylis by high performance liquid chromatography coupled with diode array detector.

PubMed

Chu, Jun; Li, Song-Lin; Yin, Zhi-Qi; Ye, Wen-Cai; Zhang, Qing-Wen

2012-07-01

A high performance liquid chromatography coupled with diode array detector (HPLC-DAD) method was developed for simultaneous quantification of eleven major bioactive components including six coumarins, three flavonoids and two limonoids in Fructus Citri Sarcodactylis. The analysis was performed on a Cosmosil 5 C(18)-MS-II column (4.6 mm × 250 mm, 5 μm) with water-acetonitrile gradient elution. The method was validated in terms of linearity, sensitivity, precision, stability and accuracy. It was found that the calibration curves for all analytes showed good linearity (R(2)>0.9993) within the test ranges. The overall limit of detection (LOD) and limit of quantification (LOQ) were less than 3.0 and 10.2 ng. The relative standard deviations (RSDs) for intra- and inter-day repeatability were not more than 4.99% and 4.92%, respectively. The sample was stable for at least 48 h. The spike recoveries of eleven components were 95.1-104.9%. The established method was successfully applied to determine eleven components in three samples from different locations. The results showed that the newly developed HPLC-DAD method was linear, sensitive, precise and accurate, and could be used for quality control of Fructus Citri Sarcodactylis. Copyright © 2012 Elsevier B.V. All rights reserved.

[Determination of carbendazim and thiabendazole in tomatoes by solid-phase microextraction coupled with high performance liquid chromatography and fluorescence detection].

PubMed

Hu, Yanxue; Yang, Xiumin; Wang, Zhi; Wang, Chun; Zhao, Jin

2005-11-01

A novel method for the determination of carbendazim (MBC) and thiabendazole (TBZ) in tomatoes by solid-phase microextraction (SPME) coupled with high performance liquid chromatography (HPLC) and fluorescence detection was developed. The experimental conditions of SPME, including extraction fiber, extraction time, extraction temperature, desorption time, desorption solvent, desorption mode, pH value, organic solvent and ionic strength, and HPLC conditions were optimized. The SPME for MBC and TBZ was performed on a 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 50 min at room temperature with the solution being stirred at 1 100 r/min. The florescence detection was made at 315 nm with excitation wavelength at 280 nm. The method is linear for MBC and TBZ over the range assayed from 0.01 to 1.0 mg/kg tomatoes with the detection limits of 0.003 mg/kg and 0. 001 mg/kg and the correlation coefficients of 0.995 8 and 0.996 7, respectively. The average recoveries for MBC and TBZ were 83.5% and 85.6% with the relative standard deviations (RSDs) of 6.5% and 3.8%, respectively. The method is fast, simple, sensitive, solvent-free and suitable for the determination of MBC and TBZ in tomatoes.

Quantitative and fingerprint analyses of Chinese sweet tea plant (Rubus Suavissimus S. Lee)

PubMed Central

Chou, Guixin; Xu, Shun-Jun; Liu, Dong; Koh, Gar Yee; Zhang, Jian; Liu, Zhijun

2009-01-01

Quality of botanical food is increasingly assessed by the content of multiple bioactive compounds. In this study we report, for the first time, an HPLC fingerprinting method for the quality evaluation of Rubus suavissimus leaves possessing multiple bioactivities. Five constituents, gallic acid, rutin, ellagic acid, rubusoside, and steviol monoside were quantified and used in developing qualitative chromatographic fingerprints. The limits of detection and quantification ranged from 0.29 μg/mL to 37.86 μg/mL. The relative standard deviations (RSDs) of intra- and inter-day precisions were no more than 3.14% and 3.01%, respectively. The average recoveries were between 93.1% and 97.5%. The developed method was validated in analyzing fourteen leaf samples with satisfactory results. The contents of the five marker compounds accounted for an average of about 6% w/w with a variability of 16% among the fourteen samples collected from a single site and year. Gallic acid was the least whereas steviol monoside the most variable compounds among the fourteen leaf samples. The characteristic compound rubusoside that is responsible for the sweet taste accounted for 5% of leaf weight. The validated method can now be used to quantitatively and qualitatively assess the quality of Rubus suavissimus leaves as traditional beverage or potential medicines. PMID:19138116

Trace determination of 10 beta-lactam antibiotics in environmental and food samples by capillary liquid chromatography.

PubMed

Bailón-Pérez, M I; García-Campaña, A M; del Olmo-Iruela, M; Gámiz-Gracia, L; Cruces-Blanco, C

2009-11-20

A sensitive and reliable method using capillary HPLC with UV-diode array detection (DAD) has been developed and validated for the trace determination of residues of 10 beta-lactam antibiotics of human and veterinary use, in milk, chicken meat and environmental water samples. The analytes included ampicillin, amoxicillin, penicillin V, penicillin G, cloxacillin, oxacillin, dicloxacillin, nafcillin, piperacillin and clavulanic acid. Legal levels are regulated by the EU Council regulation 2377/90 in animal edible tissues for these compounds. For food analysis, a solid-phase extraction (SPE) procedure consisting in a tandem of Oasis HLB and Alumina N cartridges was applied for off-line preconcentration and cleanup. For water analysis, the first step was only necessary. The limits of detection for the studied compounds were between 0.04-0.06 microg l(-1) for water samples and 0.80-1.40 microg l(-1) (or microg kg(-1)) in the case of foods derived from animals. Average recoveries for fortified samples at different concentration levels ranged between 82.9% and 98.2%, with relative standard deviations (RSDs) lower than 9%. The method showed the advantages of capillary HPLC for the detection of these widely applied antibiotics in different samples at very low concentration levels.

Voltammetric determination of copper in selected pharmaceutical preparations--validation of the method.

PubMed

Lutka, Anna; Maruszewska, Małgorzata

2011-01-01

It were established and validated the conditions of voltammetric determination of copper in pharmaceutical preparations. The three selected preparations: Zincuprim (A), Wapń, cynk, miedź z wit. C (B), Vigor complete (V) contained different salts and different quantity of copper (II) and increasing number of accompanied ingredients. For the purpose to transfer copper into solution, the samples of powdered tablets of the first and second preparation were undergone extraction and of the third the mineralization procedures. The concentration of copper in solution was determined by differential pulse voltammetry (DP) using comparison with standard technique. In the validation process, the selectivity, accuracy, precision and linearity of DP determination of copper in three preparations were estimated. Copper was determined within the concentration range of 1-9 ppm (1-9 microg/mL): the mean recoveries approached 102% (A), 100% (B), 102% (V); the relative standard deviations of determinations (RSD) were 0.79-1.59% (A), 0.62-0.85% (B) and 1.68-2.28% (V), respectively. The mean recoveries and the RSDs of determination satisfied the requirements for the analyte concentration at the level 1-10 ppm. The statistical verification confirmed that the tested voltammetric method is suitable for determination of copper in pharmaceutical preparation.

Analysis of sulfonamides, tilmicosin and avermectins residues in typical animal matrices with multi-plug filtration cleanup by liquid chromatography-tandem mass spectrometry detection.

PubMed

Qin, Yuhong; Jatamunua, Freedom; Zhang, Jingru; Li, Yanjie; Han, Yongtao; Zou, Nan; Shan, Jihao; Jiang, Yanbin; Pan, Canping

2017-05-15

The frequent use of various veterinary drugs could lead to residue bioaccumulation in animal tissues, which could cause dietary risks to human health. In order to quickly analyze the residues, a liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for detecting Sulfonamides, Tilmicosin and Avermectins (AVMs) residues in animal samples. For sample preparation, modified QuEChERS (quick, easy, cheap, effective, rugged and safe) and ultrasound-assisted extraction (UAE) methods were used. For sample cleanup, n-Hexane delipidation and multi-plug filtration cleanup (m-PFC) method based on primary-secondary amine (PSA) and octadecyl-silica (C18) were used, followed by LC-MS/MS analysis. It was validated on 7 animal matrices (bovine, caprine, swine meat and their kidneys, milk) at two fortified concentration levels of 5 and 100μg/kg. The recoveries ranged from 82 to 107% for all analytes with relative standard deviations (RSDs) less than 15%. Matrix-matched calibrations were performed with coefficients of determination above 0.998 for all analytes within concentration levels of 5-500μg/kg. The developed method was successfully used to analysis veterinary drugs of real animal samples from local markets. Copyright © 2017 Elsevier B.V. All rights reserved.

[Simultaneous determination of pyraclostrobin and thiophanate-methyl and its metabolite carbendazim residues in soil and citrus by QuEChERS-liquid chromatography- tandem mass spectrometry].

PubMed

Li, Fuqin; Shi, Lihong; Wang, Fei; Sun, Caiyuan; Kang, Di; Zhang, Yuping; Chen, Lingzhu; Hu, Deyu

2017-06-08

A QuEChERS-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of pyraclostrobin, thiophanate-methyl and its metabolite carbendazim in soil and citrus. The samples were extracted with methanol or acetonitrile, purified by primary secondary amine (PSA), then separated by LC, detected in multiple reaction monitoring (MRM) mass spectrometry mode via positive electrospray ionization. The analytes were quantified by matrix-matched standard solutions with external standard method. The limits of quantification (LOQs) of pyraclostrobin, thiophanate-methyl and carbendazim in different matrices were 5.8-7.0 μg/kg, 9.3-14.1 μg/kg and 2.1-2.6 μg/kg, respectively. For all the samples, the spiked recoveries ranged from 75.48% to 109.18%, and the relative standard deviations (RSDs) were 0.60%-5.11% ( n =5). The method is quick, easy, effective, sensitive and accurate. The matrix-matched calibration solutions can efficiently compensate matrix effects of the pyraclostrobin, thiophanate-methyl and carbendazim in LC-MS/MS analysis. The established method can be applied to the residue analysis of the real samples of soil, citrus peel, citrus pulp and citrus fruits.

[Determination of nitroaromatics and cyclo ketones in sea water' by gas chromatography coupled with activated carbon fiber solid-phase micro-extraction].

PubMed

Ma, Hanna; Zhu, Mengya; Wang, Yalin; Sun, Tonghua; Jia, Jinping

2009-05-01

A gas chromatography (GC) coupled with solid-phase micro-extraction using a special activated carbon fiber (ACF) was developed for the analysis of 6 nitroaromatics and cyclic ketones, nitrobenzene (NB), 1,3-dinitrobenzene (1,3-DNB), 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), isophorone, 1,4-naphthaquinone (1,4-NPQ), in sea water samples. The sample was extracted for 30 min under saturation of NaCl at 1,500 r/min and 60 degrees C in head space. The desorption was performance at 280 degrees C for 2 min. The linear ranges were from 0.01 to 400 microg/L. The limits of detection (LODs) were 1.4 - 3.2 ng/L. This method has been successfully applied to the determination of nitroaromatics and cyclic ketones in the sea water samples obtained from East China Sea. The concentrations of nitrobenzene, 1,3-dinitrobenzene and 2,6-dinitrotoluene in the sea water sample were 0.756, 0.944, 0.890 microg/L, respectively. The recoveries were 86.3% - 101.8% with the relative standard deviations (RSDs) of 3.7% -7.8%. The method is suitable for analyzing nitroaromatics and cyclic ketones at low concentration levels in sea water samples.

Theoretical repeatability assessment without repetitive measurements in gradient high-performance liquid chromatography.

PubMed

Kotani, Akira; Tsutsumi, Risa; Shoji, Asaki; Hayashi, Yuzuru; Kusu, Fumiyo; Yamamoto, Kazuhiro; Hakamata, Hideki

2016-07-08

This paper puts forward a time and material-saving method for evaluating the repeatability of area measurements in gradient HPLC with UV detection (HPLC-UV), based on the function of mutual information (FUMI) theory which can theoretically provide the measurement standard deviation (SD) and detection limits through the stochastic properties of baseline noise with no recourse to repetitive measurements of real samples. The chromatographic determination of terbinafine hydrochloride and enalapril maleate is taken as an example. The best choice of the number of noise data points, inevitable for the theoretical evaluation, is shown to be 512 data points (10.24s at 50 point/s sampling rate of an A/D converter). Coupled with the relative SD (RSD) of sample injection variability in the instrument used, the theoretical evaluation is proved to give identical values of area measurement RSDs to those estimated by the usual repetitive method (n=6) over a wide concentration range of the analytes within the 95% confidence intervals of the latter RSD. The FUMI theory is not a statistical one, but the "statistical" reliability of its SD estimates (n=1) is observed to be as high as that attained by thirty-one measurements of the same samples (n=31). Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of trace/ultratrace rare earth elements in environmental samples by ICP-MS after magnetic solid phase extraction with Fe3O4@SiO2@polyaniline-graphene oxide composite.

PubMed

Su, Shaowei; Chen, Beibei; He, Man; Hu, Bin; Xiao, Zuowei

2014-02-01

A novel Fe3O4@SiO2@polyaniline-graphene oxide composite (MPANI-GO) was prepared through a simple noncovalent method and applied to magnetic solid phase extraction (MSPE) of trace rare earth elements (REEs) in tea leaves and environmental water samples followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The prepared MPANI-GO was characterized by transmission electron microscopy and vibrating sample magnetometer. Various parameters affecting MPANI-GO MSPE of REEs have been investigated. Under the optimized conditions, the limits of detection (LODs, 3σ) for REEs were in the range of 0.04-1.49 ng L(-1) and the relative standard deviations (RSDs, c=20 ng L(-1), n=7) were 1.7-6.5%. The accuracy of the proposed method was validated by analyzing a Certified Reference Material of GBW 07605 tea leaves. The method was also successfully applied for the determination of trace REEs in tea leaves and environmental water samples. The developed MPANI-GO MSPE-ICP-MS method has the advantages of simplicity, rapidity, high sensitivity, high enrichment factor and is suitable for the analysis of trace REEs in samples with complex matrix. © 2013 Elsevier B.V. All rights reserved.

Label-free electrochemiluminescence biosensor for ultrasensitive detection of telomerase activity in HeLa cells based on extension reaction and intercalation of Ru(phen)3 (2.).

PubMed

Lin, Yue; Yang, Linlin; Yue, Guiyin; Chen, Lifen; Qiu, Bin; Guo, Longhua; Lin, Zhenyu; Chen, Guonan

2016-10-01

Telomerase is one of the most common markers of human malignant tumors, such as uterine, stomach, esophageal, breast, colorectal, laryngeal squamous cell, thyroid, bladder, and so on. It is necessary to develop some sensitive but convenient detection methods for telomerase activity determination. In this study, a label-free and ultrasensitive electrochemiluminescence (ECL) biosensor has been fabricated to detect the activity of telomerase extracted from HeLa cells. Thiolated telomerase substrate (TS) primer was immobilized on the gold electrode surface through gold-sulfur (Au-S) interaction and then elongated by telomerase specifically. Then, it was hybridized with complementary DNA to form double-stranded DNA (dsDNA) fragments on the electrode surface, and Ru(phen)3 (2+) has been intercalated into the dsDNA grooves to act as the ECL probe. The enhanced ECL intensity has a linear relationship with the number of HeLa cells in the range of 5∼5000 and with a detection limit of 2 HeLa cells. The proposed ECL biosensor has high specificity to telomerase in the presence of common interferents. The relative standard deviations (RSDs) were <5 % at 100 HeLa cells. The proposed method provides a convenient approach for telomerase-related cancer screening or diagnosis.

An approach to determination of phenolic compounds in seawater using SPME-GC-MS based on SWCNTs coating

NASA Astrophysics Data System (ADS)

Zhu, Jia; Wang, Ying; Zeng, Lin

2016-08-01

Phenolic compounds have become one kind of the important pollutants of the marine environment. Single-walled Carbon nanotubes, as one-dimensional nano materials, have light weight and perfect hexagonal structure of connections, with many unusual mechanical, chemical and electrical properties. In recent years, with the research of carbon nanotubes and other nano materials, the application prospect is also constantly discussed. In this paper, homemade single-walled carbon nanotubes (SWCNTs) coating was used for establishing an analytical approach to the determination of five kinds of phenolic compounds in seawater using SPME-GC-MS. Optimal conditions: After saturation was conducted with NaCl, and pH was adjusted to 2.0 with H2SO4, the extract was immersed in a water bath at 40°C for GC-MS determination through 40-min agitating extraction at 500 rmin-1 and 3-min desorption at 280°C. The liniearities ranged between 0.01-100 μg L-1, and the determination limits ranged between 1.5-10 ng L-1. The relative standard deviation (RSD, n = 5) was less than 6.5%. For the phenolic compounds obtained from the spiked recovery test for actual seawater samples, the rates of recovery were 87.5%-101.7%, and the RSDs were less than 8.8%, which met the requirements of determination. Due to its simplicity, high efficiency and low consumption, this approach is suitable for the analysis of trace amounts of phenolic compounds in marine waters.

Single-step reinforced microextraction of polycyclic aromatic hydrocarbons from soil samples using an inside needle capillary adsorption trap with electropolymerized aniline/multi-walled carbon nanotube sorbent.

PubMed

Ghiasvand, Ali Reza; Yazdankhah, Fatemeh

2017-03-03

A polyaniline/multi-wall carbon nanotubes (PANI/MWCNT) composite was electrodeposited on the interior surface of a platinized stainless steel capillary needle and used to prepare an inside needle capillary adsorption trap (INCAT) device. The platinization expanded the interior adsorbing surface of the needle and made it more porous and cohesive for nanocomposite film. The nanocomposite was characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The fabricated INCAT was fixed into a cooling capsule to fabricate a cooling-assisted INCAT (CA-INCAT) system. The CA-INCAT device was used to extract polycyclic aromatic hydrocarbons (PAHs) from solid samples followed by gas chromatography-flame ionization detection (GC-FID) determination. To obtain the best extraction efficiency, the important experimental variables were studied and optimized. Under the optimal conditions, the limits of detection (LODs) for the studied PAHs were in the range of 0.002-0.02ngg -1 . Linear dynamic ranges (LDRs) for the calibration curves were found to be 0.1-30,000ngg -1 . Relative standard deviations (RSDs%) for six replicated analysis of 1ngg -1 PAHs were obtained 7.7-11%. The CA-INCAT-GC-FID method was successfully applied for the extraction and determination of PAHs in contaminated soil samples. The results were in agreement with those obtained by a validated ultrasound-assisted solvent extraction (UA-SE) method. Copyright © 2017 Elsevier B.V. All rights reserved.

[Determination of 21 fragrance allergens in toys by gas chromatography-ion trap mass spectrometry].

PubMed

Lü, Qing; Zang, Qing; Bai, Hua; Li, Haiyu; Kang, Suyuan; Wang, Chao

2012-05-01

A method of gas chromatography-ion trap mass spectrometry (GC-IT-MS) was developed for the determination of 21 fragrance allergens in sticker toys, plush toys and plastic toys. The experimental conditions, such as sample pretreatment conditions, and the analytical conditions of GC-IT-MS, were optimized. The sticker toy samples and plush toy samples were extracted with acetone by ultrasonic wave, and the extracts were separated on an Agilent HP-1 MS column (50 m x 0.2 mm x 0.5 microm), then determined by IT-MS and quantified by external standard method. The plastic toy samples were extracted by the dissolution-precipitation approach, cleaned up with an Envi-carb solid phase extraction column and concentrated by rotary evaporation and nitrogen blowing, then determined by GC-IT-MS and quantified by external standard method. The calibration curves showed good linearity in the range of 0.002-50 mg/L with the correlation coefficients greater than 0.996 8. The limits of quantification (LOQ, S/N > 10) were 0.02-40 mg/kg. The average recoveries of the target compounds spiked in the sample at three concentration levels were in the range of 82.2%-110.8% with the relative standard deviations (RSDs) of 0.6%-10.5%. These results show that this method is accurate and sensitive for the qualitative and quantitative determination of the 21 fragrance allergens in the 3 types of toys.

[Determination of five arsenic species in rice by liquid chromatography-inductively coupled plasma-mass spectrometry].

PubMed

Gong, Jiadi; Cao, Xiaolin; Cao, Zhaoyun; Bian, Yingfang; Yu, Shasha; Chen, Mingxue

2014-07-01

A method was developed for the simultaneous determination of arsenic acid [As (V)], arsenious acid [As (III)], arsenobetaine (AsB), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in rice by liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS). The extraction reagent was 0.3 mol/L nitric acid with heat-assistant condition for 1.5 h at 95 degrees C. Then, the five arsenic species were separated by an anion exchange column (Dionex IonPac AS19, 250 mm x 4 mm) and detected by ICP-MS. Four kinds of extracted solutions were compared through the extraction efficiency. The concentration of nitric acid, the temperature and the extraction time were optimized. The recoveries of the five arsenic species spiked in rice at two levels ranged from 89.6% to 99.5% with the relative standard deviations (RSDs, n = 5) of 0.6% - 3.6%. The measured values of the arsenic species in standard rice materials were consistent with their standard values. The linear ranges were 0.05 - 200 microg/L for AsB and DMA, 0.10-400 microg/L for As (III) and MMA, 0.15-600 microg/L for As (V). The limits of detection for the five arsenic species were 0.15-0.45 microg/kg. The results showed that the method is much more precise for the risk assessment of the rice. This method is simple, accurate and durable for the determination of arsenic species in rice.

Membrane solid phase microextraction with alumina hollow fiber on line coupled with ICP-OES for the determination of trace copper, manganese and nickel in environmental water samples.

PubMed

Cui, Chao; He, Man; Hu, Bin

2011-03-15

A novel alumina hollow fiber was synthesized by sol-gel template method and was characterized by scanning electron microscopy, N(2) adsorption technique and X-ray diffraction. With the use of prepared alumina hollow fiber as extraction membrane, a new method of flow injection (FI)-membrane solid phase microextraction (MSPME) on-line coupled to inductively coupled plasma-optical emission spectrometry (ICP-OES) was developed for simultaneous determination of trace metals (Cu, Mn and Ni) in environmental water samples. The adsorption capacities of the alumina hollow fiber for Cu, Mn and Ni were found to be 6.6, 8.7 and 13.3 mg g(-1), respectively. With a preconcentration factor of 10, the limits of detection (LODs) for Cu, Mn and Ni were found to be 0.88, 0.61 and 0.38 ng mL(-1), respectively, and the relative standard deviations (RSDs) were ranging from 6.2 to 7.9% (n = 7, c = 10 ng mL(-1)). To validate the accuracy, the proposed method was applied to the analysis of certified reference material GSBZ50009-88 environmental water and the determined values are in good agreement with the certified values. The developed method was also employed for the analysis of Yangtze River water and East Lake water, and the recoveries for the spiked samples were in the range of 87.4-110.2%. Copyright © 2011 Elsevier B.V. All rights reserved.

[Determination of triclosan and triclocarban in human breast milk by solid-phase extraction and ultra performance liquid chromatography-tandem mass spectrometry].

PubMed

Zhang, Pin; Zhang, Jing; Shi, Ying; Shao, Bing

2015-03-01

An analytical method was developed to simultaneously detect triclosan (TCS) and triclocarban (TCC) in human breast milk using solid-phase extraction (SPE) with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Samples were extracted by acetonitrile and purified with C -18 SPE cartridge after enzymolysis with β-glucuronidase/arylsulfatase. The chromatographic separation was performed on a Waters ACQUITY UPLC™ HSS T3 column (100 mm x 2. 1 mm, 1. 8 µm) with gradient elution using methanol and water at a flow rate of 0. 3 ml/min. The target analytes were assayed by triple quadrupole mass spectrometer operating in the negative ion mode. Quantification was performed by isotopic internal standard calibration. Satisfactory linearity (r2 > 0. 999) was obtained over the range of 0. 2 - 20. 0 µg/L and 0. 02 - 2. 0 µg/L for triclosan and triclocarban, respectively, with the limits of quantifications (LOQs) of 0. 41 and 0. 03 µg/kg. Average recoveries of two target compounds (spiked at three concentration levels) ranged from 100. 2% to 119. 3%, with the relative standard deviations (RSDs) between 5. 91% and 11. 31% (n =6). Twenty-five real samples (n = 25) were detected containing TCS and TCC at concentrations of < LOQ - 0. 77 µg/kg and < LOQ - 4. 28 µg/kg, respectively. Due to its high sensitivity and good reproductivity, this method can be applied to analyze TCS and TCC in human breast milk.

[Determination of hydroxyproline in liver tissue by hydrophilic interaction chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry].

PubMed

Liu, Wei; Qi, Shenglan; Xu, Ying; Xiao, Zhun; Fu, Yadong; Chen, Jiamei; Yang, Tao; Liu, Ping

2017-12-08

A method for the determination of hydroxyproline (Hyp) in liver tissue of mice by hydrophilic interaction chromatography-quadrupole/electrostatic field orbitrap high resolution mass spectrometry (HILIC-HRMS) was developed. The liver tissue samples of normal mice and liver fibrosis mice induced by carbon tetrachloride were hydrolyzed by concentrated hydrochloric acid. After filtrated and diluted by solution, the diluent was separated on an Hypersil GOLD HILIC column (100 mm×2.1 mm, 3 μm). Water-acetonitrile (28:72, v/v)were used as the mobile phases with isocratic elution. Finally, the target analytes were detected in positive model by HRMS equipped with an electrospray ionization source. The linear range of hydroxyproline was from 0.78 to 100.00 μg/L with the correlation coefficient ( R 2 ) of 0.9983. The limit of quantification was 0.78 μg/L. By detecting the spiked samples, the recoveries were in the range of 97.4%-100.9% with the relative standard deviations (RSDs) between 1.4% and 2.0%. In addition, comparison of the measurement results by this method and the chloramine T method was proceeded. It was found that the linear correlation between the two methods was very good, and the Pearson correlation coefficient was 0.927. And this method had simpler operation procedure and higher accuracy than chloramine T method. This method can be used for the quick determination of hydroxyproline in liver tissue samples.

Ionic liquid molecularly imprinted polymers for application in pipette-tip solid-phase extraction coupled with gas chromatography for rapid screening of dicofol in celery.

PubMed

Yan, Hongyuan; Yang, Chen; Sun, Yunyun; Row, Kyung Ho

2014-09-26

A new type of ionic liquid molecularly imprinted polymers (IL-MIPs) synthesized by precipitation polymerization using 1-allyl-3-methylimidazolium bromide as an auxiliary solvent and α-chloro-dichlorodiphenyltrichloroethane (α-chloro-DDT) as the template was applied as a selective sorbent of minimized pipette tip-solid-phase extraction (PT-SPE) for rapid isolation and extraction of dicofol (DCF) from celery samples. The pretreatment procedure of celery samples involved only 2.0mg of IL-MIPs, 0.8 mL of acetonitrile-water (ACN-H2O; 1:1, v/v) (washing solvent), and 1.0 mL of acetone-10% acetic acid (HOAc) (elution solvent). Compared with molecularly imprinted polymers (MIPs), ionic liquid-non-imprinted polymers (IL-NIPs) and conventional sorbents such as C18, Si, NH2, and Al2O3-N, IL-MIPs showed higher adsorption and purification capacity to DCF in aqueous solution. Good linearity for DCF was observed in the range from 2.3 to 232.5 ng g(-1) (r(2)=0.9995). The average recoveries at three spiking levels ranged from 86.6% to 101.9% with relative standard deviations (RSDs) of ≤ 6.5% (n=3). The presented IL-MIPs-PT-SPE-GC/ECD method combines the advantages of MIPs, IL, and PT-SPE, and can be used in aqueous conditions with high affinity and selectivity to analytes of complex samples. Copyright © 2014 Elsevier B.V. All rights reserved.

[Direct determination of ethyl carbamate in Chinese rice wine and grape wine by ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry].

PubMed

Wang, Lijuan; Ke, Runhui; Wang, Bing; Yin, Jianjun; Song, Quanhou

2012-09-01

An ultra performance liquid chromatography-electrospray ionization tandem mass spectrometric (UPLC-ESI-MS/MS) method was established for the direct determination of ethyl carbamate in Chinese rice wine and grape wine. The Chinese rice wine and grape wine samples were diluted with distilled water, filtered through 0. 22 microm microporous membrane. The LC separation was performed on a Waters Acquity UPLC system with a BEH C18 column, acetonitrile and 0. 1% (v/v) acetic acid aqueous solution as the mobile phase. The ethyl carbamate was determined in the mode of electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM). The butyl carbamate (BC) was used as the internal standard for the quantitative determination. The calibration curve showed good linearity in the range of 2 - 500 microg/L with the correlation coefficient greater than 0.995. The limit of detection (LOD) was 1.7 microg/L and the limit of quantification (LOQ) was 5.0 microg/L. The recoveries of the ethyl carbamate in Chinese rice wine and grape wine was in the range of 90% - 102%. The relative standard deviations (RSDs) of intra-day and inter-day determinations were 0. 8% - 4.5% and 1.4% - 5.6% (n = 6). The results indicated that the proposed method is easy, fast, sensitive, and suitable for the determination of ethyl carbamate in Chinese rice wine and grape wine.

[Development and evaluation of a novel three-dimensional adjustable confocal laser-induced fluorescence detector].

PubMed

Liu, Fan; Yu, Shuxin; Tang, Tao; Sun, Yuanshe; Zhang, Weibing; Li, Tong

2011-09-01

Laser-induced fluorescence detector (LIFD) is one of the most sensitive detectors in analytical chemical files. Confocal optical configuration is widely used in LIFDs. Two effective approaches used to achieve the best signal to noise ratio (S/N) are increasing the confocal precision and minimizing the background noise. A novel three-dimensional adjustable confocal LIFD was developed, using a new three-dimensional adjustable supporter of reflector and modularized optical system. A detection limit (S/N = 3) of 1 x 10(-12) mol/L and a linear dynamic range of 3 orders of magnitude were obtained using fluorescein isothiocyanate (FITC) standard as the test sample. The noise level and drift levels were 8.0 x 10(-3) mV and 1.4 x 10(-3) mV/h, respectively, which were almost 10 times lower than before. And the stability of the LIFD was evaluated by five replicate injections of 5 x 10(-9) mol/L FITC, and the relative standard deviations (RSDs) of peak height and peak area were 0.38% and 0.41%, respectively. Further more, three biogenic amines, which were derivatized by FITC, were separated by high performance liquid chromatography (HPLC) and then detected by the novel LIFD. And the detection limits (S/N = 3) ranged 0.01 to 0.02 nmol/L, which were better than other methods. Therefore, the LIFD is highly sensitive, as well as shows a real low noise level and good reproducibility.

[Determination of 11 mycotoxins in baked foods and raw materials by ultra performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry].

PubMed

Li, Rong; He, Chunmei; Yang, Luqi; Wang, Yong; Zhang, Pengjie; Gao, Yongqing

2017-08-08

A method for the determination of 11 mycotoxins in baked foods and raw materials by ultra-high performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry (UPLC-HRMS) is reported in this paper. The samples were extracted with 20 mL 90% (v/v) acetonitrile aqueous solution containing 1% (v/v) formic acid, and the extracts were salted out by 2.0 g MgSO 4 and 0.5 g NaCl, cleaned up by 300 mg C18. The analytes were carried out on a CORTECS C18 column (100 mm×2.1 mm, 1.6 μ m) by gradient elution with 2 mmol/L ammonium acetate with 0.1% (v/v) formic acid aqueous solution and 2 mmol/L ammonium acetate methanol with 0.1% (v/v) formic acid. The results showed that the 11 mycotoxins had good linear relationships in their respective mass concentration ranges. The correlation coefficients were not less than 0.9960 and the limits of quantitation (LOQs) were from 0.15 to 20.00 μ g/kg. The recoveries of the 11 mycotoxins in bread ranged from 64.38% to 122.61% with the relative standard deviations (RSDs) from 1.52% to 12.99% at three spiked levels ( n =6). The method is demonstrated to be simple, fast, highly sensitive, reliable and it is effective to detect common mycotoxins in baked foods and raw materials.

[Determination of di (hydrogenated tallow alkyl) dimethyl ammonium compounds in textile auxiliaries by ultra-high performance liquid chromatography-tandem mass spectrometry].

PubMed

Zhu, Feng

2015-01-01

A method has been developed for the determination of di (hydrogenated tallow alkyl) dimethyl ammonium compounds (DHTDMAC) in textile auxiliaries by ultra-high performance liquid chromatography-tandem mass spectrometry. (UPLC-MS/MS). The samples were extracted and diluted with acidified methanol by 5% (v/v) formic acid under ultrasonic assistance. The separation was performed on an Eclipse Plus C18 column (50 mm x 2.1 mm, 1.8 microm) using 0.1% (v/v) formic acid solution and methanol as the mobile phases. Identification and quantification were achieved by UPLC-MS/MS with electrospray ionization (ESI) source in positive ion mode and multiple reaction monitoring (MRM) mode. The results indicated that the calibration curve of DHTDMAC showed good linear relationship between peak area and mass concentration in the range of 10-280 microg/L with the correlation coefficient (r2) of 0.9991. The limit of detection (LOD, S/N=3) and the limit of quantification (LOQ, S/N= 10) of this method were 3 mg/kg and 10 mg/kg, respectively. The average recoveries from three typical textile auxiliary matrices including dispersant, antistatic agent and fabric softener, at three spiked levels were in the range of 97.2%-108.3% with the relative standard deviations (RSDs) of 1.5%-4.6%. The method is sensitive, accurate, simple and effective for the analysis of DHTDMAC in textile auxiliaries.

Bifunctional ultrasound assisted extraction and determination of Elettaria cardamomum Maton essential oil.

PubMed

Sereshti, Hassan; Rohanifar, Ahmad; Bakhtiari, Sadjad; Samadi, Soheila

2012-05-18

A new hyphenated extraction method composed of ultrasound assisted extraction (UAE)-optimized ultrasound assisted emulsification microextraction (USAEME) was developed for the extraction and preconcentration of the essential oil of Elettaria cardamomum Maton. The essential oil was analyzed by gas chromatography-mass spectrometry (GC-MS) and optimization was performed using gas chromatography-flame ionization detection (GC-FID). Ultrasound played two different roles in the extraction of the essential oil. First, as a source of sufficient energy to break the oil-containing glands in order to release the oil, and second as an emulsifier to disperse the organic phase within water. The effective parameters (factors) of USAEME including volume of extraction solvent (C(2)H(4)Cl(2)), extraction temperature and ultrasonic time were optimized by using a central composite design (CCD). The optimal conditions were 120 μL for extraction solvent volume, 32.5 °C for temperature and 10.5 min for ultrasonic time. The linear dynamic ranges (LDRs) were 0.01-50 mg L(-1) with the determination coefficients in the range of 0.9990-0.9999. The limits of detection (LODs) and the relative standard deviations (RSDs) were 0.001-0.007 mg L(-1) and 3.6-6.3%, respectively. The enrichment factors were 93-98. The main components of the extracted essential oil were α-terpenyl acetate (46.0%), 1,8-cineole (27.7%), linalool (5.3%), α-terpineol (4.0%), linalyl acetate (3.5%). Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous determination of 3-monochloropropane-1,2-diol and acrylamide in food by gas chromatography-triple quadrupole mass spectrometry with coupled column separation.

PubMed

Xu, Xiao-min; He, Hua-li; Zhu, Yan; Feng, Liang; Ying, Ying; Huang, Bai-fen; Shen, Hai-tao; Han, Jian-long; Ren, Yi-ping

2013-01-14

Both 3-monochloropropane-1,2-diol (3-MCPD) and acrylamide are contaminants found in heat-processed foods and their related products. A quantitative method was developed for the simultaneous determination of both contaminants in food by gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The analytes were purified and extracted by the matrix solid-phase dispersion extraction (MSPDE) technique with Extrelut NT. A coupled column (a 3 m Innowax combined with a 30 m DB-5 ms) was developed to separate both compounds efficiently without derivatization. Triple quadrupole mass spectrometry in multiple reaction monitoring mode (MRM) was applied to suppress matrix interference and obtain good sensitivity in the determination of both analytes. The limit of detection (LOD) in the sample matrix was 5 μg kg(-1) for 3-MCPD or acrylamide. The average recoveries for 3-MCPD and acrylamide in different food matrices were 90.5-107% and 81.9-95.7%, respectively, with the intraday relative standard deviations (RSDs) of 5.6-13.5% and 5.3-13.4%, respectively. The interday RSDs were 6.1-12.6% for 3-MCPD and were 5.0-12.8% for acrylamide. Both contaminants were found in samples of bread, fried chips, fried instant noodles, soy sauce, and instant noodle flavoring. Neither 3-MCPD nor acrylamide was detected in the samples of dairy products (solid or liquid samples) and non-fried instant noodles. Copyright © 2012 Elsevier B.V. All rights reserved.

Anemone-like nanostructures for non-lithographic, reproducible, large-area, and ultra-sensitive SERS substrates

NASA Astrophysics Data System (ADS)

Daglar, Bihter; Demirel, Gokcen Birlik; Khudiyev, Tural; Dogan, Tamer; Tobail, Osama; Altuntas, Sevde; Buyukserin, Fatih; Bayindir, Mehmet

2014-10-01

The melt-infiltration technique enables the fabrication of complex nanostructures for a wide range of applications in optics, electronics, biomaterials, and catalysis. Here, anemone-like nanostructures are produced for the first time under the surface/interface principles of melt-infiltration as a non-lithographic method. Functionalized anodized aluminum oxide (AAO) membranes are used as templates to provide large-area production of nanostructures, and polycarbonate (PC) films are used as active phase materials. In order to understand formation dynamics of anemone-like structures finite element method (FEM) simulations are performed and it is found that wetting behaviour of the polymer is responsible for the formation of cavities at the caps of the structures. These nanostructures are examined in the surface-enhanced-Raman-spectroscopy (SERS) experiment and they exhibit great potential in this field. Reproducible SERS signals are detected with relative standard deviations (RSDs) of 7.2-12.6% for about 10 000 individual spots. SERS measurements are demonstrated at low concentrations of Rhodamine 6G (R6G), even at the picomolar level, with an enhancement factor of ~1011. This high enhancement factor is ascribed to the significant electric field enhancement at the cavities of nanostructures and nanogaps between them, which is supported by finite difference time-domain (FDTD) simulations. These novel nanostructured films can be further optimized to be used in chemical and plasmonic sensors and as a single molecule SERS detection platform.The melt-infiltration technique enables the fabrication of complex nanostructures for a wide range of applications in optics, electronics, biomaterials, and catalysis. Here, anemone-like nanostructures are produced for the first time under the surface/interface principles of melt-infiltration as a non-lithographic method. Functionalized anodized aluminum oxide (AAO) membranes are used as templates to provide large-area production of nanostructures, and polycarbonate (PC) films are used as active phase materials. In order to understand formation dynamics of anemone-like structures finite element method (FEM) simulations are performed and it is found that wetting behaviour of the polymer is responsible for the formation of cavities at the caps of the structures. These nanostructures are examined in the surface-enhanced-Raman-spectroscopy (SERS) experiment and they exhibit great potential in this field. Reproducible SERS signals are detected with relative standard deviations (RSDs) of 7.2-12.6% for about 10 000 individual spots. SERS measurements are demonstrated at low concentrations of Rhodamine 6G (R6G), even at the picomolar level, with an enhancement factor of ~1011. This high enhancement factor is ascribed to the significant electric field enhancement at the cavities of nanostructures and nanogaps between them, which is supported by finite difference time-domain (FDTD) simulations. These novel nanostructured films can be further optimized to be used in chemical and plasmonic sensors and as a single molecule SERS detection platform. Electronic supplementary information (ESI) available: SEM images of the AAO membrane and bare polymer film, FEM simulations of anemone-like polymeric nanopillars depending on the time and pressure, and detailed calculation of the enhancement factor both including experimental and theoretical approaches. See DOI: 10.1039/c4nr03909b

Simultaneous Determination of 11 Aminoglycoside Residues in Honey, Milk, and Pork by Liquid Chromatography with Tandem Mass Spectrometry and Molecularly Imprinted Polymer Solid Phase Extraction.

PubMed

Yang, Bixia; Wang, Lian; Luo, Chunying; Wang, Xixi; Sun, Chengjun

2017-11-01

An analytical method was developed for the simultaneous determination of 11 aminoglycoside (AG) antibiotics, including amikacin, paromomycin, dihydrostreptomycin, gentamicin C1a, hygromycin, kanamycin, netilmicin, spectinomycin, sisomicin, streptomycin, and tobramycin in honey, milk, and pork samples by LC with tandem MS and molecularly imprinted polymer (MIP) SPE. The AG antibiotics in milk and homogenated meat samples were extracted with a solution composed of 10 mmol/L potassium dihydrogen phosphate, 0.4 mmol/L EDTA-Na2, and 2% trichloroacetic acid. For honey samples, the extractant was 50 mmol/L potassium dihydrogen phosphate. The extracts were cleaned up with MIP SPE cartridges. The separation was performed on a zwitter ionic-HILIC column (50 × 2.1 mm, 3.5 μm), with the mobile phase consisting of methanol, 0.3% formic acid, and 175 mmol/L ammonium formate at 0.50 mL/min in gradient elution. A triple-quadrupole mass spectrometer equipped with an electrospray ionization source, which was operated in positive mode, was used for detection. The quantification was based on matrix-matched calibration curves. The method was applied to real samples with three different matrixes. The LODs of the method were 2-30 μg/kg and the LOQs were 7-100 μg/kg; the average recovery ranged from 78.2 to 94.8%; intraday RSDs and interday RSDs were ≤15 and ≤18%, respectively; and the absolute values of matrix effect for all AGs were RSDs ≤23%.

Development and Validation of a Reliable and Robust Method for the Analysis of Cannabinoids and Terpenes in Cannabis.

PubMed

Giese, Matthew W; Lewis, Mark A; Giese, Laura; Smith, Kevin M

2015-01-01

The requirements for an acceptable cannabis assay have changed dramatically over the years resulting in a large number of laboratories using a diverse array of analytical methodologies that have not been properly validated. Due to the lack of sufficiently validated methods, we conducted a single- laboratory validation study for the determination of cannabinoids and terpenes in a variety of commonly occurring cultivars. The procedure involves high- throughput homogenization to prepare sample extract, which is then profiled for cannabinoids and terpenes by HPLC-diode array detector and GC-flame ionization detector, respectively. Spike recovery studies for terpenes in the range of 0.03-1.5% were carried out with analytical standards, while recovery studies for Δ9-tetrahydrocannabinolic acid, cannabidiolic acid, Δ9-tetrahydrocannabivarinic acid, and cannabigerolic acid and their neutral counterparts in the range of 0.3-35% were carried out using cannabis extracts. In general, accuracy at all levels was within 5%, and RSDs were less than 3%. The interday and intraday repeatabilities of the procedure were evaluated with five different cultivars of varying chemotype, again resulting in acceptable RSDs. As an example of the application of this assay, it was used to illustrate the variability seen in cannabis coming from very advanced indoor cultivation operations.

High polar organic-inorganic hybrid coating stir bar sorptive extraction combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry for the speciation of seleno-amino acids and seleno-oligopeptides in biological samples.

PubMed

Mao, Xiangju; Hu, Bin; He, Man; Chen, Beibei

2012-09-21

In this work, partially sulfonated polystyrene-titania (PSP-TiO(2)) organic-inorganic hybrid stir bar coating was prepared by sol-gel and blending methods, and a new method of PSP-TiO(2) coating stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) was established for the analysis of seleno-amino acids (selenocystine (SeCys(2)), methylseleno-cysteine (MeSeCys), selenomethionine (SeMet) and selenoethionine (SeEt)) and seleno-oligopeptides (γ-glutamyl-Se-methyl-selenocysteine (γ-GluMeSeCys) and selenodiglutathione (GS-Se-SG)) in biological samples. The prepared high polar PSP-TiO(2) hybrid coating avoided the swelling of PSP and cracking of TiO(2) coating by combining the good film-forming property of PSP with the high mechanical strength of TiO(2). The scanning electron microscope (SEM) showed that no obvious swelling and damage occurred for the PSP-TiO(2) hybrid stir bar coating after 30 extraction/desorption cycles. The preparation reproducibility of PSP-TiO(2) coated stir bar, evaluated with the relative standard deviations (RSDs), was in the range of 6.7-12.6% (n=5) in one batch, and 9.9-17.6% (n=7) among different batches. The limits of detection (LODs) of the developed method for six target selenium species were in the range of 50.2-185.5 ngL(-1) (as (77)Se) and 45.9-158.8 ngL(-1) (as (82)Se) with the RSDs within 4.9-11.7%. The dynamic linear range was found to cover three orders of magnitude with correlation coefficient of 0.9995-0.9999. The developed method was applied for the analysis of Certified Reference Material SELM-1 selenium enriched yeast and the determined values were in good agreement with the certified values. The method has also been applied for the analysis of seleno-amino acids and seleno-oligopeptides in human urine and garlic samples. Different from the conventional organic polymer SBSE coatings (such as polydimethylsiloxane, PDMS), the extraction mechanism of PSP-TiO(2) organic-inorganic hybrid SBSE coating was based on the cation exchange interaction, which made it feasible to directly extract high polar seleno-amino acids and seleno-oligopeptides in biological samples without derivatization. This coating could also be suitable for stir bar sorptive extraction of other cationic compounds from the environmental and biological samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Mycotoxin Analysis of Human Urine by LC-MS/MS: A Comparative Extraction Study

PubMed Central

Escrivá, Laura; Font, Guillermina

2017-01-01

The lower mycotoxin levels detected in urine make the development of sensitive and accurate analytical methods essential. Three extraction methods, namely salting-out liquid–liquid extraction (SALLE), miniQuEChERS (quick, easy, cheap, effective, rugged, and safe), and dispersive liquid–liquid microextraction (DLLME), were evaluated and compared based on analytical parameters for the quantitative LC-MS/MS measurement of 11 mycotoxins (AFB1, AFB2, AFG1, AFG2, OTA, ZEA, BEA, EN A, EN B, EN A1 and EN B1) in human urine. DLLME was selected as the most appropriate methodology, as it produced better validation results for recovery (79–113%), reproducibility (RSDs < 12%), and repeatability (RSDs < 15%) than miniQuEChERS (71–109%, RSDs <14% and <24%, respectively) and SALLE (70–108%, RSDs < 14% and < 24%, respectively). Moreover, the lowest detection (LODS) and quantitation limits (LOQS) were achieved with DLLME (LODs: 0.005–2 μg L−1, LOQs: 0.1–4 μg L−1). DLLME methodology was used for the analysis of 10 real urine samples from healthy volunteers showing the presence of ENs B, B1 and A1 at low concentrations. PMID:29048356

Polymeric microchip for the simultaneous determination of anions and cations by hydrodynamic injection using a dual-channel sequential injection microchip electrophoresis system.

PubMed

Gaudry, Adam J; Nai, Yi Heng; Guijt, Rosanne M; Breadmore, Michael C

2014-04-01

A dual-channel sequential injection microchip capillary electrophoresis system with pressure-driven injection is demonstrated for simultaneous separations of anions and cations from a single sample. The poly(methyl methacrylate) (PMMA) microchips feature integral in-plane contactless conductivity detection electrodes. A novel, hydrodynamic "split-injection" method utilizes background electrolyte (BGE) sheathing to gate the sample flows, while control over the injection volume is achieved by balancing hydrodynamic resistances using external hydrodynamic resistors. Injection is realized by a unique flow-through interface, allowing for automated, continuous sampling for sequential injection analysis by microchip electrophoresis. The developed system was very robust, with individual microchips used for up to 2000 analyses with lifetimes limited by irreversible blockages of the microchannels. The unique dual-channel geometry was demonstrated by the simultaneous separation of three cations and three anions in individual microchannels in under 40 s with limits of detection (LODs) ranging from 1.5 to 24 μM. From a series of 100 sequential injections the %RSDs were determined for every fifth run, resulting in %RSDs for migration times that ranged from 0.3 to 0.7 (n = 20) and 2.3 to 4.5 for peak area (n = 20). This system offers low LODs and a high degree of reproducibility and robustness while the hydrodynamic injection eliminates electrokinetic bias during injection, making it attractive for a wide range of rapid, sensitive, and quantitative online analytical applications.

Novel Palm Fatty Acid Functionalized Magnetite Nanoparticles for Magnetic Solid-Phase Extraction of Trace Polycyclic Aromatic Hydrocarbons from Environmental Samples.

PubMed

Rozi, Siti Khalijah Mahmad; Nodeh, Hamid Rashidi; Kamboh, Muhammad Afzal; Manan, Ninie Suhana Abdul; Mohamad, Sharifah

2017-07-01

A novel adsorbent, palm fatty acid coated magnetic Fe 3 O 4 nanoparticles (MNP-FA) was successfully synthesized with immobilization of the palm fatty acid onto the surface of MNPs. The successful synthesis of MNP-FA was further confirmed by X-Ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and Energy dispersive X-Ray spectroscopy (EDX) analyses and water contact angle (WCA) measurement. This newly synthesized MNP-FA was applied as magnetic solid phase extraction (MSPE) adsorbent for the enrichment of polycyclic aromatic hydrocarbons (PAHs), namely fluoranthene (FLT), pyrene (Pyr), chrysene (Cry) and benzo(a)pyrene (BaP) from environmental samples prior to High Performance Liquid Chromatography- Diode Array Detector (HPLC-DAD) analysis. The MSPE method was optimized by several parameters such as amount of sorbent, desorption solvent, volume of desorption solvent, extraction time, desorption time, pH and sample volume. Under the optimized conditions, MSPE method provided a low detection limit (LOD) for FLT, Pyr, Cry and BaP in the range of 0.01-0.05 ng mL -1 . The PAHs recoveries of the spiked leachate samples ranged from 98.5% to 113.8% with the RSDs (n = 5) ranging from 3.5% to 12.2%, while for the spiked sludge samples, the recoveries ranged from 81.1% to 119.3% with the RSDs (n = 5) ranging from 3.1% to 13.6%. The recyclability study revealed that MNP-FA has excellent reusability up to five times. Chromatrographic analysis demonstrated the suitability of MNP-FA as MSPE adsorbent for the efficient extraction of PAHs from environmental samples.

Coupling carbon nanotube film microextraction with desorption corona beam ionization for rapid analysis of Sudan dyes (I-IV) and Rhodamine B in chilli oil.

PubMed

Chen, Di; Huang, Yun-Qing; He, Xiao-Mei; Shi, Zhi-Guo; Feng, Yu-Qi

2015-03-07

A rapid analysis method by coupling carbon nanotube film (CNTF) microextraction with desorption corona beam ionization (DCBI) was developed for the determination of Sudan dyes (I-IV) and Rhodamine B in chilli oil samples. Typically, CNTF was immersed into the diluted solution of chilli oil for extraction, which was then placed directly under the visible plasma beam tip of the DCBI source for desorption and ionization. Under optimized conditions, five dyes were simultaneously determined using this method. Results showed that the analytes were enriched by the CNTF through the π-π interactions, and the proposed method could significantly improve the sensitivities of these compounds, compared to the direct analysis by DCBI-MS/MS. The method with a linear range of 0.08-12.8 μg g(-1) and good linear relationships (R(2) > 0.93) in a multiple reaction monitoring (MRM) mode was developed. Satisfactory reproducibility was achieved. Relative standard deviations (RSDs) were less than 20.0%. The recoveries ranged from 80.0 to 110.0%, and the limits of detection (LODs) were in the range of 1.4-21 ng g(-1). Finally, the feasibility of the method was further exhibited by the determination of five illegal dyes in chilli powder. These results demonstrate that the proposed method consumes less time and solvent than conventional HPLC-based methods and avoids the contamination of chromatographic column and ion source from non-volatile oil. With the help of a 72-well shaker, multiple samples could be treated simultaneously, which ensures high throughput for the entire pretreatment process. In conclusion, it provides a rapid and high-throughput approach for the determination of such illicit additions in chilli products.

Preparation, characterization and application of Saussurea tridactyla Sch-Bip as green adsorbents for preconcentration of rare earth elements in environmental water samples

NASA Astrophysics Data System (ADS)

Zhang, Qiangying; He, Man; Chen, Beibei; Hu, Bin

2016-07-01

This paper deals with preparation, characterization and application of the Saussurea tridactyla Sch-Bip (STSB) as a new green adsorbent for separation of matrix elements and preconcentration of rare earth elements (REEs) in environmental water samples. The pretreated STSB adsorbent with 2 mol L- 1 NaOH is characterized with higher surface area and adsorption capacities in comparison with a raw STSB material. The new adsorbent was used for the development of on-line solid phase extraction (SPE) for the determination of REEs by radial viewing 27 MHz inductively coupled plasma optical emission spectrometry (ICP-OES). Various parameters affecting the adsorption/desorption procedure were optimized. The adsorption capacities for the STSB were found to be 62.2 (Y)-153 mg g- 1 (Tm). Under the optimized conditions, the limits of detection (LODs, 3σ) for REEs were in the range of 0.06 (Yb)-8.77 (Sm) ng mL- 1. The relative standard deviations (RSDs) for 7 replicate determinations of target REEs at low concentration level ranged from 2.4 (Yb) to 8.9 (Sm)%. The adsorption isotherm fitted Langmuir model and the adsorption kinetics fitted well with both Pseudo-first order and Pseudo-second order models. The predominant adsorption mechanism is ion exchange. The STSB pretreated with 2 mol L- 1 NaOH has been demonstrated to be low cost, green and environment friendly adsorbent, featuring with high adsorption capacity, wide pH range, and fast adsorption/desorption kinetics for target REEs with long lifetime. The proposed method was applied to the determination of REEs in East Lake, Yangtze River and rain water samples.

Graphene oxide/polyethyleneglycol composite coated stir bar for sorptive extraction of fluoroquinolones from chicken muscle and liver.

PubMed

Fan, Wenying; He, Man; Wu, Xiaoran; Chen, Beibei; Hu, Bin

2015-10-30

Graphene oxide (GO) is an ideal adsorbent for polar and less polar compounds due to its hexagonal carbon network structure with oxygen-containing groups, while its strong hydrophilicity and water solubility limited its application in sample pretreatment techniques. Herein, GO was composited with polyethyleneglycol (PEG) or polyaniline (PAN) through intermolecular interactions to improve its stability, and the GO/PEG and GO/PAN composite coated stir bars were prepared by sol-gel technique. Compared with GO/PAN composite and polydimethylsiloxane (PDMS) coated stir bar, the prepared GO/PEG composite coated stir bar exhibited higher extraction efficiency for five fluoroquinolones (FQs). Based on it, a method of GO/PEG composite coated stir bar sorptive extraction (SBSE) combined with high-performance liquid chromatography-fluorescence detector (HPLC-FLD) was proposed. The factors influencing SBSE, such as sample pH, salt effect, stirring rate, extraction time, desorption solvent and desorption time, were optimized, and the analytical performance of the developed SBSE-HPLC-FLD method was evaluated. The limits of detection (LODs) for five FQs were in the range of 0.0045-0.0079μgL(-1), and the enrichment factors (EFs) were in the range of 41.5-65.5-fold (theoretical enrichment factor was 100-fold). The reproducibility was also investigated at concentrations of 0.05μgL(-1) and the relative standard deviations (RSDs, n=6) were found to be in the range of 4.6-12.1%. The proposed method was successfully applied for the determination of FQs in chicken muscle and chicken liver samples. Copyright © 2015 Elsevier B.V. All rights reserved.

In situ metathesis reaction combined with liquid-phase microextraction based on the solidification of sedimentary ionic liquids for the determination of pyrethroid insecticides in water samples.

PubMed

Hu, Lu; Zhang, Panjie; Shan, Wanyu; Wang, Xuan; Li, Songqing; Zhou, Wenfeng; Gao, Haixiang

2015-11-01

A novel dispersion liquid-liquid microextraction method based on the solidification of sedimentary ionic liquids (SSIL-DLLME), in which an in situ metathesis reaction forms an ionic liquid (IL) extraction phase, was developed to determine four pyrethroid insecticides (i.e., permethrin, cyhalothrin, fenpropathrin, and transfluthrin) in water followed by separation using high-performance liquid chromatography. In the developed method, in situ DLLME was used to enhance the extraction efficiency and yield. After centrifugation, the extraction solvent, tributyldodecylphosphonium hexafluorophosphate ([P44412][PF6]), was easily collected by solidification in the bottom of the tube. The effects of various experimental parameters, the quantity of tributyldodecylphosphonium bromide ([P44412]Br), the molar ratio of [P44412]Br to potassium hexafluorophosphate (KPF6), the ionic strength, the temperature of the sample solution, and the centrifugation time, were optimized using a Plackett-Burman design to identify the significant factors that affected the extraction efficiency. These significant factors were then optimized using a central composite design. Under the optimized conditions, the recoveries of the four pyrethroid insecticides at four spiked levels ranged from 87.1% to 101.7%, with relative standard deviations (RSDs) ranging from 0.1% to 5.5%. At concentration levels between 1 and 500 µg/L, good linearity was obtained, with coefficients of determination greater than 0.9995. The limits of detection (LODs) for the four pyrethroid insecticides were in the range of 0.71-1.54 µg/L. The developed method was then successfully used for the determination of pyrethroid insecticides in environmental samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Polydimethylsiloxane/metal-organic frameworks coated stir bar sorptive extraction coupled to high performance liquid chromatography-ultraviolet detector for the determination of estrogens in environmental water samples.

PubMed

Hu, Cong; He, Man; Chen, Beibei; Zhong, Cheng; Hu, Bin

2013-10-04

In this work, three kinds of metal-organic frameworks (MOFs), MOF-5, MOF-199 and IRMOF-3, were introduced in stir bar sorptive extraction (SBSE) and novel polydimethylsiloxane (PDMS)/MOFs (including PDMS/MOF-5, PDMS/MOF-199 and PDMS/IRMOF-3) coated stir bars were prepared by sol-gel technique. These PDMS/MOFs coatings were characterized and critically compared for the extraction of seven target estrogens (17-β-estradiol, dienestrol, diethylstilbestrol, estrone, 4-t-octylphenol, bisphenol-A and 17α-ethynylestradiol) by SBSE, and the results showed that PDMS/IRMOF-3 exhibited highest extraction efficiency. Based on the above facts, a novel method of PDMS/IRMOF-3 coating SBSE-high performance liquid chromatography ultraviolet (HPLC-UV) detection was developed for the determination of seven target estrogens in environmental waters. Several parameters affecting extraction of seven target estrogens by SBSE (PDMS/IRMOF-3) including extraction time, stirring rate, pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.15-0.35 μg/L. The linear range was 2-2,500 μg/L for 17α-ethynylestradiol and 1-2,500 μg/L for other estrogens. The relative standard deviations (RSDs) were in the range of 3.7-9.9% (n=8, c=20 μg/L) and the enrichment factors were from 30.3 to 55.6-fold (theoretical enrichment factor was 100-fold). The proposed method was successfully applied to the analysis of estrogens in environmental water samples, and quantitative recoveries were obtained for the spiking experiments. Copyright © 2013 Elsevier B.V. All rights reserved.

Suitable conditions for liquid-phase microextraction using solidification of a floating drop for extraction of fat-soluble vitamins established using an orthogonal array experimental design.

PubMed

Sobhi, Hamid Reza; Yamini, Yadollah; Esrafili, Ali; Abadi, Reza Haji Hosseini Baghdad

2008-07-04

A simple, rapid and efficient microextraction method for the extraction and determination of some fat-soluble vitamins (A, D2, D3) in aqueous samples was developed. For the first time orthogonal array designs (OADs) were employed to screen the liquid-phase microextraction (LPME) method in which few microliters of 1-undecanol were delivered to the surface of the aqueous sample and it was agitated for a selected time. Then sample vial was cooled by inserting it into an ice bath for 5 min. The solidified solvent was transferred into a suitable vial and immediately melted. Then, the extract was directly injected into a high-performance liquid chromatography (HPLC) for analysis. Several factors affecting the microextraction efficiency such as sample solution temperature, stirring speed, volume of the organic solvent, ionic strength and extraction time were investigated and screened using an OA16 (4(5)) matrix. Under the best conditions (temperature, 55 degrees C; stirring speed, 1000 rpm; the volume of extracting solvent, 15.0 microL; no salt addition and extraction time, 60 min), detection limits of the method were in the range of 1.0-3.5 microgL(-1). The relative standard deviations (RSDs) to determine the vitamins at microg L(-1) levels by applying the proposed method varied in the range of 5.1-10.7%. Dynamic linear ranges of 5-500 mugL(-1) with good correlation coefficients (0.9984

Optimization and application of parallel solid-phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry for the determination of 11 aminoglycoside residues in honey and royal jelly.

PubMed

Wang, Xinran; Yang, Shupeng; Li, Yi; Zhang, Jinzhen; Jin, Yue; Zhao, Wen; Zhang, Yongxin; Huang, Jingping; Wang, Peng; Wu, Cuiling; Zhou, Jinhui

2018-03-23

A robust and sensitive method of solid-phase extraction followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established and performed for the simultaneous determination of eleven aminoglycosides (AGs) in royal jelly and honey. After sample extraction by a phosphate buffer containing trichloroacetic acid (TCA) and ethylenediaminetetracetic acid disodium salt (Na 2 EDTA), the extraction solution was subjected to a parallel solid-phase extraction for clean-up prior to the LC-MS/MS analysis. The same method was applied to analyze two completely different matrices, honey and royal jelly. Good sensitivity, repeatability, and recovery were obtained by using the mobile phase without an ion-pairing reagent such as heptafluorobutyric acid (HFBA) or sodium heptanesulfonate. The calibration curves of the honey and royal jelly samples exhibited a good linear response (R 2  > 0.99) at six concentrations in the range of 10-1000 μg/mL. The limit of quantification (LOQ) of the AGs ranged from 10 to 25 μg/kg in the honey and from 12.5 to 25 μg/kg in the royal jelly. The recoveries of the AGs for the honey and royal jelly samples were in the range of 79.48% to 108.95% and 74.61% to 113.70% respectively and the relative standard deviations (RSDs) were between 1.23% and 9.59%, and between 1.51% and 9.98%, respectively. The proposed approach has been allowed in China as a reference method for the simultaneous determination of eleven AGs in honey and royal jelly. Copyright © 2018 Elsevier B.V. All rights reserved.

Nanofibers mat-based solid-phase extraction method for the pretreatment of urine samples and its application in the primary study on the disposition of nonylphenol after long-term low-level exposure in rats.

PubMed

Qian, Liangliang; Li, Ruixian; Di, Qiannan; Shen, Yang; Xu, Qian; Li, Jian

2017-09-01

A method was established for the analysis of nonylphenol (NP) in rat urine samples based on a solid-phase extraction (SPE) procedure with an amino functionalized polyacrylonitrile nanofibers mat (NH 2 -PAN NF S M) as sorbent coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The calibration curves prepared in three different days showed good linearity over a wide range of NP concentrations from 0.1 to 100.0ng/mL. It was remarkable that the proposed NH 2 -PAN NFsM based SPE method showed superior extraction efficiency with the consumption of only 4mg of sorbent and 500μL of eluent. The eluent without any further concentration was directly analyzed by HPLC-MS/MS. As a result, a simple and effective sample preparation was achieved. In addition, the notable lower detection limit (LOD) of 0.03ng/mL revealed the excellent sensitivity of the proposed method in comparison with that in literatures. The recoveries ranged from 85.0% to 114.8% with the relative standard deviations (RSDs) ranging from 7.5% to 13.7%, which were better than or comparable to those from the published methods, suggesting high accuracy of the proposed method. The proposed method was applied in primary study on the disposition of nonylphenol after long-term low-level exposure in rats, providing information for health risk assessment on the real scenarios of NP exposure. NH 2 -PAN NFsM shows great potential as a novel SPE sorbent for the analysis of biological samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Magnetic microsphere-confined graphene for the extraction of polycyclic aromatic hydrocarbons from environmental water samples coupled with high performance liquid chromatography-fluorescence analysis.

PubMed

Wang, Weina; Ma, Ruiyang; Wu, Qiuhua; Wang, Chun; Wang, Zhi

2013-06-07

In this paper, a magnetic microsphere-confined graphene adsorbent (Fe3O4@SiO2-G) was fabricated and used for the extraction of five polycyclic aromatic hydrocarbons (fluorene, anthracene, phenanthrene, fluoranthene and pyrene) from environmental water samples prior to high performance liquid chromatography with fluorescence detection. The Fe3O4@SiO2-G was characterized by various instrumental methods. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe3O4@SiO2-G, the pH and ionic strength of sample solution, the extraction time and the desorption conditions, were investigated. Due to the high surface area and excellent adsorption capacity of the Fe3O4@SiO2-G, satisfactory extraction can be achieved with only 15mg of the adsorbent per 250mL solution and 5min extraction. Under the optimum conditions, a linear response was observed in the concentration range of 5-1500ngL(-1) for fluorene, 2.5-1500ngL(-1) for anthracene and 15-1500ngL(-1) for phenanthrene, fluoranthene and pyrene, with the correlation coefficients (r) ranging from 0.9897 to 0.9961. The limits of detection (S/N=3) of the method were between 0.5 and 5.0ngL(-1). The relative standard deviations (RSDs) were less than 5.6%. The recoveries of the method were in the range between 83.2% and 108.2%. The results indicated that this graphene-based magnetic nanocomposite had a great adsorptive ability toward the five polycyclic aromatic hydrocarbons from environmental water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Dispersive liquid-liquid microextraction based on the solidification of floating organic drop followed by ICP-MS for the simultaneous determination of heavy metals in wastewaters

NASA Astrophysics Data System (ADS)

Li, Yong; Peng, Guilong; He, Qiang; Zhu, Hui; Al-Hamadani, Sulala M. Z. F.

2015-04-01

In the present work, a dispersive liquid-liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) combined with inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of Pb, Co, Cu, Ni, Zn. The influences of analytical parameters, including pH, extraction solvent volume, disperser solvent volume, concentration of chelating agent on the quantitative recoveries of Pb, Co, Cu, Ni, Zn were investigated. The effect of the interfering ions on the analytes recovery was also investigated. Under the optimized conditions, the limits of detection were 0.97-2.18 ng L-1. The relative standard deviations (RSDs) were 2.62-4.51% (n = 7, C = 20 ng L-1). The proposed method was successfully applied for the analysis of ultra trace metals in wastewater samples.

Bias correction of surface downwelling longwave and shortwave radiation for the EWEMBI dataset

NASA Astrophysics Data System (ADS)

Lange, Stefan

2018-05-01

Many meteorological forcing datasets include bias-corrected surface downwelling longwave and shortwave radiation (rlds and rsds). Methods used for such bias corrections range from multi-year monthly mean value scaling to quantile mapping at the daily timescale. An additional downscaling is necessary if the data to be corrected have a higher spatial resolution than the observational data used to determine the biases. This was the case when EartH2Observe (E2OBS; Calton et al., 2016) rlds and rsds were bias-corrected using more coarsely resolved Surface Radiation Budget (SRB; Stackhouse Jr. et al., 2011) data for the production of the meteorological forcing dataset EWEMBI (Lange, 2016). This article systematically compares various parametric quantile mapping methods designed specifically for this purpose, including those used for the production of EWEMBI rlds and rsds. The methods vary in the timescale at which they operate, in their way of accounting for physical upper radiation limits, and in their approach to bridging the spatial resolution gap between E2OBS and SRB. It is shown how temporal and spatial variability deflation related to bilinear interpolation and other deterministic downscaling approaches can be overcome by downscaling the target statistics of quantile mapping from the SRB to the E2OBS grid such that the sub-SRB-grid-scale spatial variability present in the original E2OBS data is retained. Cross validations at the daily and monthly timescales reveal that it is worthwhile to take empirical estimates of physical upper limits into account when adjusting either radiation component and that, overall, bias correction at the daily timescale is more effective than bias correction at the monthly timescale if sampling errors are taken into account.

Determination of some organophosphorus pesticides in water and watermelon samples by microextraction prior to high-performance liquid chromatography.

PubMed

Wang, Chun; Wu, Qiuhua; Wu, Chunxia; Wang, Zhi

2011-11-01

A novel method based on simultaneous liquid-liquid microextraction and carbon nanotube reinforced hollow fiber microporous membrane solid-liquid phase microextraction has been developed for the determination of six organophosphorus pesticides, i.e. isocarbophos, phosmet, parathion-methyl, triazophos, fonofos and phoxim, in water and watermelon samples prior to high-performance liquid chromatography (HPLC). Under the optimum conditions, the method shows a good linearity within a range of 1-200 ng/mL for water samples and 5-200 ng/g for watermelon samples, with the correlation coefficients (r) varying from 0.9990 to 0.9997 and 0.9986 to 0.9995, respectively. The limits of detection (LODs) were in the range between 0.1 and 0.3 ng/mL for water samples and between 1.0 and 1.5 ng/g for watermelon samples. The recoveries of the method at spiking levels of 5.0 and 50.0 ng/mL for water samples were between 85.4 and 100.8%, and at spiking levels of 5.0 and 50.0 ng/g for watermelon samples, they were between 82.6 and 92.4%, with the relative standard deviations (RSDs) varying from 4.5-6.9% and 5.2-7.4%, respectively. The results suggested that the developed method represents a simple, low-cost, high analytes preconcentration and excellent sample cleanup procedure for the determination of organophosphorus pesticides in water and watermelon samples. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Determination of six novel amide fungicides in vegetables and fruits by liquid chromatography-tandem mass spectrometry].

PubMed

Chen, Xiaolong; Li, Zhengxiang; Cao, Zhaoyun; Cao, Xiaolin; Chen, Mingxue

2013-10-01

A method was developed for the simultaneous determination of mepanipyrim, silthiofam, boscalid, fluopicolide, mandipropamid, cyflufenamid in vegetables and fruits by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The analytes were extracted from the samples by acetonitrile and purified by Florisil SPE. The six novel amide fungicides were separated on a Poroshell 120 EC-C18 column with the mobile phases of water and acetonitrile, and finally detected by MS/MS with positive electrospray ionization (ESI+) in multiple reaction monitoring (MRM) mode, quantified by external standard method. Under the optimal analytical conditions, the correlation coefficients (r) of the six novel amide fungicides were not lower than 0. 999 0 in the concentration range from 0.5 to 100 microg/L. The limits of detection (S/N > or = 3) of the method were 0.15 microg/kg for boscalid, silthiofam, mandipropamid, cyflufenamid, 0.10 microg/kg for mepanipyrim and 0.17 microg/kg for fluopicolide. The recovery tests were performed for the 7 types of vegetables and the 3 types of fruits at the spiked levels of 0.5, 5 and 50 microg/kg, and the recoveries of the six analytes ranged from 65% to 124% with the relative standard deviations (RSDs, n = 5) of 1%-18%. The matrix effects in vegetables and fruits of the six amide fungicides were significantly reduced by the purification of Florisil SPE compared with the modified QuEChERS. The method is easy, fast, sensitive and accurate, and can meet the requirements of the determination of the six amide fungicide residues in vegetables and fruits.

Magnetic mesoporous molecularly imprinted polymers based on surface precipitation polymerization for selective enrichment of triclosan and triclocarban.

PubMed

Wang, Xuemei; Huang, Pengfei; Ma, Xiaomin; Du, Xinzhen; Lu, Xiaoquan

2018-02-16

Novel magnetic mesoporous molecularly imprinted polymers (MMIPs) were prepared based on surface precipitation polymerization using Triclosan (TCS) as template and methacrylic acid as functional monomer. The synthesized MMIPs-TCS were applied to the adsorbent of magnetic solid-phase extraction (MSPE) coupled with HPLC for the enrichment and determination of TCS. The MMIPs-TCS were characterized by fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N 2 adsorption-desorption transmission, and vibrating sample magnetometry. Under the optimum condition, the MMIPs-TCS-MSPE-HPLC method shows low limits of detection (LODs) (0.20-0.90 μg L -1 ) and limits of quantification detection (LOQs) (0.66-2.97 μg L -1 ), wide linear ranges from 10.0 to 1000 μg L -1 for each compound with exception of 2,4,6-TCP from 20.0 to 1000 μg L -1 , and acceptable reproducibility (relative standard deviation, RSD <6.6% for intra-day, RSD <8.1% for inter-day). The satisfactory recoveries were in the range of 89.5%-108.4% with good RSDs less than 8.0% at the three spiked levels of 20, 50 and 80 μg L -1 . Moreover, the adsorption experiments show the MMIPs-TCS possess rapid binding affinity, excellent magnetic response, specific selectivity and high adsorption capacity toward TCS with a maximum adsorption capacity of 1955.8 μg g -1 . Copyright © 2018 Elsevier B.V. All rights reserved.

Comparison of two methods for selegiline determination: A flow-injection chemiluminescence method using cadmium sulfide quantum dots and corona discharge ion mobility spectrometry.

PubMed

Khataee, Alireza; Lotfi, Roya; Hasanzadeh, Aliyeh; Iranifam, Mortaza; Zarei, Mahmoud; Joo, Sang Woo

2016-01-15

Two analytical approaches including chemiluminescence (CL) and corona discharge ionization ion mobility spectrometry (CD-IMS) were developed for sensitive determination of selegiline (SG). We found that the CL intensity of the KMnO4-Na2S2O3 CL system was significantly enhanced in the presence of L-cysteine capped CdS quantum dots (QDs). A possible CL mechanism for this CL reaction is proposed. In the presence of SG, the enhanced CL system was inhibited. Based on this inhibition, a simple and sensitive flow-injection CL method was proposed for the determination of SG. Under optimum experimental conditions, the decreased CL intensity was proportional to SG concentration in the range of 0.01 to 30.0 mg L(-1). The detection limit (3σ) was 0.004 mg L(-1). Also, SG was determined using CD-IMS, and under optimum conditions of CD-IMS, calibration curves were linear in the range of 0.15 to 42.0 mg L(-1), with a detection limit (3σ) of 0.03 mg L(-1). The precision of the two methods was calculated by analyzing samples containing 5.0 mg L(-1) of SG (n=11). The relative standard deviations (RSDs%) of the flow-injection CL and CD-IMS methods are 2.17% and 3.83%, respectively. The proposed CL system exhibits a higher sensitivity and precision than the CD-IMS method for the determination of SG. Copyright © 2015. Published by Elsevier B.V.

A novel metal-organic framework composite MIL-101(Cr)@GO as an efficient sorbent in dispersive micro-solid phase extraction coupling with UHPLC-MS/MS for the determination of sulfonamides in milk samples.

PubMed

Jia, Xiuna; Zhao, Pan; Ye, Xiu; Zhang, Lianjun; Wang, Ting; Chen, Qinyu; Hou, Xiaohong

2017-07-01

As a novel material, metal-organic framework/graphite oxide (MIL-101(Cr)@GO) has great potential for the pretreatment of trace analytes. In the present study, MIL-101(Cr)@GO was synthesized using a solvothermal synthesis method at the nanoscale and was applied as sorbent in the dispersive micro-solid phase extraction (DMSPE) for the enrichment of the trace sulfonamides (SAs) from milk samples for the first time. Several experimental parameters including kinds of sorbents, the effect of pH, the amount of MIL-101(Cr)@GO, ionic strength, adsorption time, desorption solvent and desorption time were investigated. Under the optimal conditions, the linear ranges were from 0.1 to 10μg/L, 0.2-20μg/L or 0.5-50μg/L for the analytes with regression coefficients (r) from 0.9942 to 0.9999. The limits of detection were between 0.012 and 0.145μg/L. The recoveries ranged from 79.83% to 103.8% with relative standard deviations (RSDs)<10% (n=3). MIL-101(Cr)@GO exhibited remarkable advantages compared to MIL-101(Cr), MIL-100(Fe), activated carbon and other sorbent materials used in pretreatment methods. A simple, rapid, sensitive, inexpensive and less solvent consuming method of DMSPE-ultra-high performance liquid chromatography-tandem mass spectrometry (DMSPE-UHPLC-MS/MS) was successfully applied to the pre-concentration and determination of twelve SAs in milk samples. Copyright © 2016 Elsevier B.V. All rights reserved.

[Analysis of sulfonamide residues in pork and chicken by high performance liquid chromatography coupled with solid-phase extraction using multiwalled carbon nanotubes as adsorbent].

PubMed

Zhao, Haixiang; Liu, Haiping; Yan, Zaoying

2014-03-01

A multi-residue analytical method based on solid-phase extraction (SPE) with multiwalled carbon nanotubes (MWCNTs) as sorbent was developed. The determination of the sulfonamides (SAs) in pork and chicken was carried out by high performance liquid chromatography-ultraviolet detection (HPLC-UV). The clean-up conditions were optimized. The analytes were extracted by acetonitril and cleaned-up by MWCNTs SPE cartridge. The extract was redissolved with the Na2HPO4 buffer (pH 5.5-6.0) for loading, and was washed with acetone-hexane (5:95, v/v), then eluted with acetone-dichloromethane (1:1, v/v) from the column. The mobile phase used in the chromatographic separation consisted of a binary mixture of acetonitrile and 50 mmol/L NaH2PO4 with the volume ratio of 7:3. A wide linear range was 0.01-1.00 mg/L with the correlation coefficients above 0.998. The limits of detection (S/N = 3) were 0.003 mg/L, and the limits of quantification (S/N = 10) were 0.01 mg/L. The average recoveries were over 70% for the nine SAs in the spiked range of 0.02-0.2 mg/kg, with the relative standard deviations (RSDs) lower than 8%. This study indicated that the MWCNTs SPE cartridge is efficient for the clean-up of the SAs in animal tissues or products, and the method is simple, accurate and suitable for the quantification of the SAs residues.

Contributing effect of various washing procedures and additives on the decline pattern of diethofencarb in crown daisy, a model of leafy vegetables.

PubMed

Kim, Sung-Woo; Abd El-Aty, A M; Choi, Jeong-Heui; Lee, Young-Jun; Lieu, Truong T B; Chung, Hyung Suk; Rahman, Md Musfiqur; Choi, Ok-Ja; Shin, Ho-Chul; Rhee, Gyu-Seek; Chang, Moon-Ik; Kim, Hee Jung; Shim, Jae-Han

2016-06-15

The effects of various washing procedures, including stagnant, running, and stagnant and running tap water, and the use of washing solutions and additives, namely NaCl (1% and 2%), vinegar (2%, 5%, and 10%), detergent (0.5% and 1%), and charcoal (1% and 2%), on the reduction rate of diethofencarb were estimated in field-incurred crown daisy, a model of leafy vegetables, grown under greenhouses located in 3 different areas (Gwangju, Naju, and Muan). The original Quick, Easy, Cheap, Effective, Rugged, and Safe "QuEChERS" method was modified for extraction and liquid chromatography-tandem mass spectrometry (LC/MS/MS) was used for analysis. The recovery of diethofencarb in unwashed and washed samples was satisfactory and ranged between 84.28% and 115.32% with relative standard deviations (RSDs) of <6%. The residual levels decreased following washing with stagnant, running, and stagnant+running tap water (i.e., decline in levels increased from 65.08% to 85.02%, 69.99 to 86.79, and 74.75 to 88.96, respectively). The percentage of decline increased and ranged from 77.46% to 91.19% following washing with various solutions. Application of 1% detergent was found to be the most effective washing method for reducing the residues in crown daisy. Additionally, washing with stagnant and running tap water or even stagnant water for 5 min might reduce the residue levels substantially, making the prepared food safe for human consumption. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Simultaneous determination of 6 forbidden colorants in cosmetics by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Lin, Weixuan; Sun, Xingquan; Zhao, Xuerong; Xu, Wei; Guo, Guiyuan

2012-05-01

A method of high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) has been established for the simultaneous determination of six forbidden colorants including Sudan IV, Acid Violet 49, Sudan Blue 2, Solvent Red 49, Basic Violet 1 and Pigment Orange 5 in cream and powdery matrix cosmetics. The samples were extracted with ethanol-acetonitrile (3:2, v/v) solution by ultrasonic technique for 20 min, then centrifuged for purification and enriched by nitrogen blowing sequentially. The analytes were isolated on a Luna C18 column (150 mm x 2.1 mm, 5 microm) by gradient elution with methanol and 10 mmol/L ammonium acetate as the mobile phases, and detected by MS/MS in the multiple reaction monitoring (MRM) mode. The qualitative analysis was based on the retention time and the relative abundance ratio of the characteristic ions, and the quantitative analysis on calibration curve method. The results showed that the limits of quantification (LOQ, S/N= 10) of the six colorants ranged from 0.1 to 10 microg/kg and the average recoveries were from 86.67% to 98.22% with the relative standard deviations (RSDs) from 4.01% to 7.01%. The method is simple and rapid with high sensitivity and good reproducibility, and suitable for the determination of the six forbidden colorants in cosmetics.

[Rapid screening and confirmation of 205 pesticide residues in rice by QuEChERS and liquid chromatography-mass spectrometry].

PubMed

Chen, Xi; Cheng, Lei; Qu, Shichao; Huang, Daliang; Liu, Jiacheng; Cui, Han; Jia, Yanbo; Ji, Mingshan

2015-10-01

A method for rapid screening and confirmation of 205 pesticide residues in rice was developed by combining QuEChERS and high performance liquid chromatography-triple quadrupole-linear ion trap mass spectrometry (LC-Q-TRAP/MS). The rice samples were extracted with acetonitrile, and then cleaned up with primary secondary amine (PSA), anhydrous magnesium sulfate (MgSO4) and C18 adsorbent. Finally, the samples were detected by LC-Q-TRAP/MS in multiple reaction monitoring with information-dependent acquisition of enhanced product ion (MRM-IDA-EPI) mode followed with database searching. A total of 205 pesticide residues were confirmed by retention times, ion pairs and the database searching using EPI library, and quantified by external standard method. All the pesticides showed good linearities with linear correlation coefficients all above 0.995. The limits of quantification (LOQs) for the 205 pesticides were 0.5-10.0 μg/kg. The average recoveries of the 205 pesticides ranged from 62.4% to 127.1% with the relative standard deviations (RSDs) of 1.0% - 20.0% at spiked levels of 10 μg/kg and 50 μg/kg, and only 20 min were needed for the analysis of an actual rice sample. In brief, the method is fast, accurate and highly sensitive, and is suitable for the screening and confirmation of pesticide residues in rice.

Polymer monolithic capillary microextraction on-line coupled with inductively coupled plasma-mass spectrometry for the determination of trace Au and Pd in biological samples

NASA Astrophysics Data System (ADS)

Liu, Xiaolan; He, Man; Chen, Beibei; Hu, Bin

2014-11-01

A novel method based on on-line polymer monolithic capillary microextraction (CME)-inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of trace Au and Pd in biological samples. For this purpose, poly(glycidyl methacrylate-ethylene dimethacrylate) monolith was prepared and functionalized with mercapto groups. The prepared monolith exhibited good selectivity to Au and Pd, and good resistance to strong acid with a long life span. Factors affecting the extraction efficiency of CME, such as sample acidity, sample flow rate, eluent conditions and coexisting ion interference were investigated in detail. Under the optimal conditions, the limits of detection (LODs, 3σ) were 5.9 ng L- 1 for Au and 8.3 ng L- 1 for Pd, and the relative standard deviations (RSDs, c = 50 ng L-1, n = 7) were 6.5% for Au and 1.1% for Pd, respectively. The developed method was successfully applied to the determination of Au and Pd in human urine and serum samples with the recovery in the range of 84-118% for spiked samples. The developed on-line polymer monolithic CME-ICP-MS method has the advantages of rapidity, simplicity, low sample/reagent consumption, high sensitivity and is suitable for the determination of trace Au and Pd in biological samples with limited amount available and complex matrix.

[Determination of patulin in fruits and jam by solid phase extraction-ultra performance liquid chromatography].

PubMed

Lü, Weichao; Shen, Shuchang; Wang, Chao

2017-11-08

With magnesium silicate, silica gel, diatomite and calcium sulfate as raw materials, a new solid phase extraction column was prepared through a series of processes of grinding to ethanol homogenate, drying and packing into polypropylene tube. The sample was hydrolyzed by pectinase, extracted by acetonitrile and purified by solid phase extraction. The target compounds were separated on a C18 column (100 mm×2.1 mm, 1.8 μm), using 0.8% (v/v) tetrahydrofuran solution as mobile phase with a flow rate of 0.5 mL/min. The detection wavelength was 276 nm. The effect of pectinase on extraction yield and purification effect of solid-phase extraction column were investigated. The optimum chromatographic conditions were selected. There was a good linear relationship between the peak heights and the mass concentrations of patulin in the range of 0.1 to 10 mg/L with the correlation coefficient ( R 2 ) of 1. The limit of detection for this method was 10.22 μg/kg. The spiked recoveries of samples were 86.58%-94.84% with the relative standard deviations (RSDs) of 1.45%-2.28%. The results indicated that the self-made solid phase extraction column had a good purification efficiency, and the UPLC had a high separation efficiency. The method is simple, accurate and of great significance for the quality and safety control of fruit products.

Chemometric-assisted QuEChERS extraction method for post-harvest pesticide determination in fruits and vegetables

NASA Astrophysics Data System (ADS)

Li, Minmin; Dai, Chao; Wang, Fengzhong; Kong, Zhiqiang; He, Yan; Huang, Ya Tao; Fan, Bei

2017-02-01

An effective analysis method was developed based on a chemometric tool for the simultaneous quantification of five different post-harvest pesticides (2,4-dichlorophenoxyacetic acid (2,4-D), carbendazim, thiabendazole, iprodione, and prochloraz) in fruits and vegetables. In the modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method, the factors and responses for optimization of the extraction and cleanup analyses were compared using the Plackett-Burman (P-B) screening design. Furthermore, the significant factors (toluene percentage, hydrochloric acid (HCl) percentage, and graphitized carbon black (GCB) amount) were optimized using a central composite design (CCD) combined with Derringer’s desirability function (DF). The limits of quantification (LOQs) were estimated to be 1.0 μg/kg for 2,4-D, carbendazim, thiabendazole, and prochloraz, and 1.5 μg/kg for iprodione in food matrices. The mean recoveries were in the range of 70.4-113.9% with relative standard deviations (RSDs) of less than 16.9% at three spiking levels. The measurement uncertainty of the analytical method was determined using the bottom-up approach, which yielded an average value of 7.6%. Carbendazim was most frequently found in real samples analyzed using the developed method. Consequently, the analytical method can serve as an advantageous and rapid tool for determination of five preservative pesticides in fruits and vegetables.

An efficient approach to selective electromembrane extraction of naproxen by means of molecularly imprinted polymer-coated multi-walled carbon nanotubes-reinforced hollow fibers.

PubMed

Tahmasebi, Zeinab; Davarani, Saied Saeed Hosseiny; Asgharinezhad, Ali Akbar

2016-10-28

In this work, a novel microextraction technique using molecularly imprinted polymer-coated multi-walled carbon nanotubes (MIP-MWCNTs) in electromembrane extraction (EME) procedure is described. The method in combination with HPLC-UV was utilized to determine naproxen, as an acidic model drug, in urine, plasma and wastewater samples. For this purpose, MIP-MWCNTs were placed in the pores of polypropylene hollow fiber. The MIP-MWCNTs-EME method has the advantages of high selectivity and cleanup of MIP along with high enrichment ability of the EME in a single step extraction. Continuing with the research, optimization of the factors affecting the migration of naproxen from sample solutions to MIP-MWCNTs sites and then into the lumen of hollow fiber was explored. Under the optimized conditions, the limit of detection (LOD) of the developed method was calculated to be 0.3μgL -1 . All relative standard deviations (RSDs) were lower than 3%. Linearity of the method was obtained within the range of 1-1000μgL -1 with the coefficient of determination (r 2 ) being higher than 0.999. Under the optimized conditions, an extraction recovery of 66% was obtained, which corresponded to a preconcentration factor of 88. Finally, the developed method was satisfactorily used to determine naproxen in urine, plasma and wastewater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemometric-assisted QuEChERS extraction method for post-harvest pesticide determination in fruits and vegetables

PubMed Central

Li, Minmin; Dai, Chao; Wang, Fengzhong; Kong, Zhiqiang; He, Yan; Huang, Ya Tao; Fan, Bei

2017-01-01

An effective analysis method was developed based on a chemometric tool for the simultaneous quantification of five different post-harvest pesticides (2,4-dichlorophenoxyacetic acid (2,4-D), carbendazim, thiabendazole, iprodione, and prochloraz) in fruits and vegetables. In the modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method, the factors and responses for optimization of the extraction and cleanup analyses were compared using the Plackett–Burman (P–B) screening design. Furthermore, the significant factors (toluene percentage, hydrochloric acid (HCl) percentage, and graphitized carbon black (GCB) amount) were optimized using a central composite design (CCD) combined with Derringer’s desirability function (DF). The limits of quantification (LOQs) were estimated to be 1.0 μg/kg for 2,4-D, carbendazim, thiabendazole, and prochloraz, and 1.5 μg/kg for iprodione in food matrices. The mean recoveries were in the range of 70.4–113.9% with relative standard deviations (RSDs) of less than 16.9% at three spiking levels. The measurement uncertainty of the analytical method was determined using the bottom-up approach, which yielded an average value of 7.6%. Carbendazim was most frequently found in real samples analyzed using the developed method. Consequently, the analytical method can serve as an advantageous and rapid tool for determination of five preservative pesticides in fruits and vegetables. PMID:28225030

Chemometric-assisted QuEChERS extraction method for post-harvest pesticide determination in fruits and vegetables.

PubMed

Li, Minmin; Dai, Chao; Wang, Fengzhong; Kong, Zhiqiang; He, Yan; Huang, Ya Tao; Fan, Bei

2017-02-22

An effective analysis method was developed based on a chemometric tool for the simultaneous quantification of five different post-harvest pesticides (2,4-dichlorophenoxyacetic acid (2,4-D), carbendazim, thiabendazole, iprodione, and prochloraz) in fruits and vegetables. In the modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method, the factors and responses for optimization of the extraction and cleanup analyses were compared using the Plackett-Burman (P-B) screening design. Furthermore, the significant factors (toluene percentage, hydrochloric acid (HCl) percentage, and graphitized carbon black (GCB) amount) were optimized using a central composite design (CCD) combined with Derringer's desirability function (DF). The limits of quantification (LOQs) were estimated to be 1.0 μg/kg for 2,4-D, carbendazim, thiabendazole, and prochloraz, and 1.5 μg/kg for iprodione in food matrices. The mean recoveries were in the range of 70.4-113.9% with relative standard deviations (RSDs) of less than 16.9% at three spiking levels. The measurement uncertainty of the analytical method was determined using the bottom-up approach, which yielded an average value of 7.6%. Carbendazim was most frequently found in real samples analyzed using the developed method. Consequently, the analytical method can serve as an advantageous and rapid tool for determination of five preservative pesticides in fruits and vegetables.

Determination of total phthalate in cosmetics using a simple three-phase sample preparation method.

PubMed

Liu, Laping; Wang, Zhengmeng; Zhao, Sihan; Duan, Jiahui; Tao, Hu; Wang, Wenji; Liu, Shuhui

2018-02-01

A simple sample preparation method requiring minimal organic solvents is proposed for the determination of the total phthalate content in cosmetics by high-performance liquid chromatography-tandem mass spectrometry. The hydrolysis of phthalates and purification of interfering substances were performed in a three-phase system that included an upper n-hexane phase, a middle ethanol phase, and a lower aqueous alkali solution. This three-phase system utilized an incremental purification strategy. The apolar ingredients were extracted with n-hexane, the polar pigments accumulated in the ethanol phase, and the hydrolysis product, phthalic acid, remained in the hydrolysate. Under the optimized conditions, the correlation coefficients (r) for the calibration curves were 0.998-0.999 in the range 0.60-12 mol L -1 . The limit of detection was 5.1 μmol kg -1 , and the limit of quantification was 9.2 μmol kg -1 . The recoveries varied from 84 to 97% with RSDs equal to or lower than 11%. The intra-day and inter-day repeatability values, expressed as the relative standard deviation, were less than 8.7 and 9.8, respectively. No obvious matrix effect existed in the different cosmetics matrices. The validated method was applied for the analysis of 57 commercial cosmetic samples. Graphical abstract Analysis of phthalates in cosmetics using a three-phase preparation method.

CE-MS analysis of heroin and its basic impurities using a charged polymer-protected gold nanoparticle-coated capillary.

PubMed

Zhang, Zhengxiang; Yan, Bo; Liu, Kelin; Liao, Yiping; Liu, Huwei

2009-01-01

The first application of charged polymer-protected gold nanoparticles (Au NPs) as semi-permanent capillary coating in CE-MS was presented. Poly(diallyldimethylammonium chloride) (PDDA) was the only reducing and stabilizing agent for Au NPs preparation. Stable and repeatable coating with good tolerance to 0.1 M HCl, methanol, and ACN was obtained via a simple rinsing procedure. Au NPs enhanced the coating stability toward flushing by methanol, improved the run-to-run and capillary-to-capillary repeatabilities, and improved the separation efficiency of heroin and its basic impurities for tracing geographical origins of illicit samples. Baseline resolution of eight heroin-related alkaloids was achieved on the PDDA-protected Au NPs-coated capillary under the optimum conditions: 120 mM ammonium acetate (pH 5.2) with addition of 13% methanol, separation temperature 20 degrees C, applied voltage -20 kV, and capillary effective length 60.0 cm. CE-MS analysis with run-to-run RSDs (n=5) of migration time in the range of 0.43-0.62% and RSDs (n=5) of peak area in the range of 1.49-4.68% was obtained. The established CE-MS method would offer sensitive detection and confident identification of heroin and related compounds and provide an alternative to LC-MS and GC-MS for illicit drug control.

Simultaneous determination of low-molecular-weight organic acids and chlorinated acid herbicides in environmental water by a portable CE system with contactless conductivity detection.

PubMed

Xu, Yan; Wang, Weilong; Li, Sam Fong Yau

2007-05-01

This report describes a method to simultaneously determine 11 low-molecular-weight (LMW) organic acids and 16 chlorinated acid herbicides within a single run by a portable CE system with contactless conductivity detection (CCD) in a poly(vinyl alcohol) (PVA)-coated capillary. Under the optimized condition, the LODs of CE-CCD ranged from 0.056 to 0.270 ppm, which were better than for indirect UV (IUV) detection of the 11 LMW organic acids or UV detection of the 16 chlorinated acid herbicides. Combined with an on-line field-amplified sample stacking (FASS) procedure, sensitivity enhancement of 632- to 1078-fold was achieved, with satisfactory reproducibility (RSDs of migration times less than 2.2%, and RSDs of peak areas less than 5.1%). The FASS-CE-CCD method was successfully applied to determine the two groups of acidic pollutants in two kinds of environmental water samples. The portable CE-CCD system shows advantages such as simplicity, cost effectiveness, and miniaturization. Therefore, the method presented in this report has great potential for onsite analysis of various pollutants at the trace level.

Polymeric Sorbent with Controlled Surface Polarity: An Alternate for Solid-Phase Extraction of Nerve Agents and Their Markers from Organic Matrix.

PubMed

Roy, Kanchan Sinha; Purohit, Ajay Kumar; Chandra, Buddhadeb; Goud, D Raghavender; Pardasani, Deepak; Dubey, Devendra Kumar

2018-06-05

Extraction and identification of lethal nerve agents and their markers in complex organic background have a prime importance from the forensic and verification viewpoint of the Chemical Weapons Convention (CWC). Liquid-liquid extraction with acetonitrile and commercially available solid phase silica cartridges are extensively used for this purpose. Silica cartridges exhibit limited applicability for relatively polar analytes, and acetonitrile extraction shows limited efficacy toward relatively nonpolar analytes. The present study describes the synthesis of polymeric sorbents with tunable surface polarity, their application as a solid-phase extraction (SPE) material against nerve agents and their polar as well as nonpolar markers from nonpolar organic matrices. In comparison with the acetonitrile extraction and commercial silica cartridges, the new sorbent showed better extraction efficiency toward analytes of varying polarity. The extraction parameters were optimized for the proposed method, which included ethyl acetate as an extraction solvent and n-hexane as a washing solvent. Under optimized conditions, method linearity ranged from 0.10 to 10 μg mL -1 ( r 2 = 0.9327-0.9988) for organophosphorus esters and 0.05-20 μg mL -1 ( r 2 = 0.9976-0.9991) for nerve agents. Limits of detection (S:N = 3:1) in the SIM mode were found in the range of 0.03-0.075 μg mL -1 for organophosphorus esters and 0.015-0.025 μg mL -1 for nerve agents. Limits of quantification (S:N = 10:1) were found in the range of 0.100-0.25 μg mL -1 for organophosphorus esters and 0.05-0.100 μg mL -1 for nerve agents in the SIM mode. The recoveries of the nerve agents and their markers ranged from 90.0 to 98.0% and 75.0 to 95.0% respectively. The repeatability and reproducibility (with relative standard deviations (RSDs) %) for organophosphorus esters were found in the range of 1.35-8.61% and 2.30-9.25% respectively. For nerve agents, the repeatability range from 1.00 to 7.75% and reproducibility were found in the range of 2.17-6.90%.

Changes in the soil microbial community after reductive soil disinfestation and cucumber seedling cultivation.

PubMed

Huang, Xinqi; Liu, Liangliang; Wen, Teng; Zhang, Jinbo; Wang, Fenghe; Cai, Zucong

2016-06-01

Reductive soil disinfestation (RSD) has been proven to be an effective and environmentally friendly way to control many soilborne pathogens and diseases. In this study, the RSDs using ethanol (Et-RSD) and alfalfa (Al-RSD) as organic carbons were performed in a Rhizoctonia solani-infected soil, and the dissimilarities of microbial communities during the RSDs and after planting two seasons of cucumber seedlings in the RSDs-treated soil were respectively investigated by MiSeq pyrosequencing. The results showed that, as for bacteria, Coprococcus, Flavisolibacter, Rhodanobacter, Symbiobacterium, and UC-Ruminococcaceae became the dominant bacterial genera at the end of Al-RSD. In contrast, Et-RSD soil involved more bacteria belonging to Firmicutes, such as Sedimentibacter, UC-Gracilibacteraceae, and Desulfosporosinus. For fungi, Chaetomium significantly increased at the end of RSDs, while Rhizoctonia and Aspergillus significantly decreased. After planting two seasons of cucumber seedlings, those bacteria belonging to Firmicutes significantly decreased, but Lysobacter and Rhodanobacter belonging to the phylum Proteobacteria as well as UC-Sordariales and Humicola belonging to Ascomycota alternatively increased in Al- and Et-RSD-treated soils. Besides, some nitrification, denitrification, and nitrogen fixation genes were apparently increased in the RSD-treated soils, but the effect was more profound in Al-RSD than Et-RSD. Overall, Et-RSD could induced more antagonists belonging to Firmicutes under anaerobic condition, whereas Al-RSD could continuously stimulate some functional microorganisms (Lysobacter and Rhodanobacter) and further improve nitrogen transformation activities in the soil at the coming cropping season.

Development of novel sol-gel coatings by chemically bonded ionic liquids for stir bar sorptive extraction--application for the determination of NSAIDS in real samples.

PubMed

Fan, Wenying; Mao, Xiangju; He, Man; Chen, Beibei; Hu, Bin

2014-11-01

In this work, a novel ionic liquid (IL) chemically bonded sol-gel coating was prepared for stir bar sorptive extraction (SBSE) of nonsteroidal anti-inflammatory drugs (NSAIDs) followed by high-performance liquid chromatography-ultraviolet detection (HPLC-UV). By using γ-(methacryloxypropyl)trimethoxysilane (KH-570) as a bridging agent, 1-allylimidazolium tetrafluoroborate ([AIM][BF4]) was chemically bonded onto the bare stir bar, and the prepared IL-bonded sol-gel stir bar coating showed higher extraction efficiency and better adsorption/desorption kinetics for target NSAIDs over other polydimethylsiloxane (PDMS)-based or monolithic stir bar coatings. The mechanical strength and durability (chemical/thermal stability) of the prepared IL-bonded sol-gel coating were excellent. The influencing factors of SBSE, such as sample pH, salt effect, stirring rate, extraction time, desorption solvent, and desorption time, were optimized, and the analytical performance of the developed SBSE-HPLC-UV method was evaluated under the optimized conditions. The limits of detection (LODs) of the proposed method for three NSAIDs were in the range of 0.23-0.31 μg L(-1), and the enrichment factors (EFs) were in the range of 51.6-56.3 (theoretical enrichment factor was 100). The reproducibility was also investigated at concentrations of 5, 20, and 100 μg L(-1), and the relative standard deviations (RSDs) were found to be less than 9.5, 7.5, and 7.6 %, respectively. The proposed method was successfully applied for the determination of NSAIDs in environmental water, urine, and milk samples.

[Simultaneous determination of nine estrogens in eel by ultrafast liquid chromatography-tandem mass spectrometry with isotope dilution technique and solid-phase extraction].

PubMed

Chen, Xiaohong; Yao, Shanshan; Li, Xiaoping; Zhao, Yonggang; Jin, Micong

2012-11-01

Developing a rapid and sensitive analytical method based on ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) with solid-phase extraction (SPE) for the simultaneous determination of nine estrogens (dienestrol, diethylstilbestrol, estrone, hexestrol, 17-alpha-estradiol, 17-beta-estradiol, estriol, 17alpha-ethinylestradiol and estradiol valerate) in eel. After the sample was extracted by acetonitrile and cleaned by Waters Oasis HLB solid-phase extraction cartridge, the UFLC separation was performed on a Shim-pack XR-ODS II column (100 mm x 2.0 mm, 2.2 microm) with a linear gradient elution program of methanol solution containing 0.04% ammonia (v/v) and 0.04% ammonia aqueous solution (v/v) as the mobile phase. Electrospray ionization was applied and operated in the negative multiple reaction monitoring (MRM) mode. The quantitation was used by isotope internal standard dilution technique. The results showed that the limits of quantitation (LOQs, S/N(10) were in the range of 0.07-0.4 microg/kg, the calibration curves were in good linearities for the nine analytes in the range of 0.5-50.0 microg/L with the correlative coefficients (r2) more than 0.998, the recoveries were between 81.0% and 110.0% with the relative standard deviations (RSDs) of 1.92%-8.24%. Additional, the mass spectra characterization of the nine estrogens was discussed and the fragmentation pathways were speculated. The developed method is rapid, sensitive, specific and reproducible, and adapts not only to the simultaneous determination of the nine trace estrogens including the epimer of 17-alpha-estradiol and 17-beta-estradiol but also to the identified detection in other fish tissues.

Residue analysis of four diacylhydrazine insecticides in fruits and vegetables by Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method using ultra-performance liquid chromatography coupled to tandem mass spectrometry.

PubMed

Liu, Xingang; Xu, Jun; Dong, Fengshou; Li, Yuanbo; Song, Wenchen; Zheng, Yongquan

2011-08-01

The new analytical method using Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) procedure for simultaneous determination of diacylhydrazine insecticide residues in fruits and vegetables was developed using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The four insecticides (tebufenozide, methoxfenozide, chromafenozide, and halofenozide) were extracted from six fruit and vegetable matrices using acetonitrile and subsequently cleaned up using primary secondary amine (PSA) or octadecylsilane (C18) as sorbent prior to UPLC-MS/MS analysis. The determination of the target compounds was achieved in less than 3.0 min using an electrospray ionization source in positive mode (ESI+) for tebufenozide, methoxfenozide, and halofenozide and in negative mode (ESI-) for chromafenozide. The limits of detection were below 0.6 μg kg(-1), while the limit of quantification did not exceed 2 μg kg(-1) in different matrices. The QuEChERS procedure by using two sorbents (PSA and C18) and the matrix-matched standards gave satisfactory recoveries and relative standard deviation (RSD) values in different matrices at four spiked levels (0.01, 0.05, 0.1, and 1 mg kg(-1)). The overall average recoveries for this method in apple, grape, cucumber, tomato, cabbage, and spinach at four levels ranged from 74.2% to 112.5% with RSDs in the range of 1.4-13.8% (n = 5) for all analytes. This study provides a theoretical basis for China to draw up maximum residue limits and analytical method for diacylhydrazine insecticide in vegetables and fruits.

Simultaneous determination of three acidic herbicide residues in food crops using HPLC and confirmation via LC-MS/MS.

PubMed

Shin, Eun-Ho; Choi, Jeong-Heui; Abd El-Aty, A M; Khay, Sathya; Kim, Sun-Ju; Im, Moo Hyeog; Kwon, Chan-Hyeok; Shim, Jae-Han

2011-01-01

2,4-D, dicamba and 4-CPA with auxin-like activity have been intensively used in agriculture, for the control of unwanted broadleaf weeds. An analytical method involving HPLC coupled with UVD was developed for the simultaneous analysis of these three analytes in Chinese cabbage, apple and pepper fruits (representative non-fatty samples) and brown rice and soybean (representative fatty samples) using liquid-liquid partitioning and column cleanup procedures. The residues were confirmed via tandem mass spectrometry (MS/MS) in ion electrospray ionization (ESI) mode. The standard curves were linear over the range of the tested concentrations (0.25-10 microg/mL), as shown by a marked linearity in excess of 0.9999 (r(2) ). The average recoveries (mean, n = 3) ranged from 94.30 to 102.63 in Chinese cabbage, from 94.76 to 108.47 in apple, from 97.52 to 102.27 in pepper, from 76.19 to 101.90 in brown rice, and from 74.60 to 107.39 in soybean. The relative standard deviations (RSDs) were <9% in all tested matrices. The limits of detection and quantitation were 0.006 and 0.02 mg/kg, respectively. Samples purchased from local markets were analyzed to evaluate the applicability of the methods developed herein. The concentration of the 2,4-D residue was measured at 0.102 mg/kg in the soybean sample; however, this level is exactly the same MRL set by the Korea Food and Drug Administration. This developed method deserves full and complete consideration, as it clearly displays the sensitivity, accuracy and precision required for residue analysis of 2,4-D, dicamba and 4-CPA in food crops. 2010 John Wiley & Sons, Ltd.

Monolithic column modified with bifunctional ionic liquid and styrene stationary phases for capillary electrochromatography.

PubMed

Mao, Zhenkun; Chen, Zilin

2017-01-13

A novel monolithic column with ionic liquid and styrene-modified bifunctional group was prepared for capillary electrochromatography (CEC) by in situ copolymerization in a ternary porogenic solvent. Ionic liquid (1-allyl-methylimidazolium chloride, AlMeIm + Cl - ) and styrene served as the bifunctional monomer, while ethylene dimethacrylate (EDMA) was used as the cross-linker. The monomer of AlMeIm + Cl - was introduced as anion-exchange group, while styrene as hydrophobic and aromatic group; the similar conjugated structure in AlMeIm + Cl - and styrene was beneficial for offeing obvious synergistic effect. The bifunctional stationary phase possessed powerful selectivity for the separation of neutral compounds, acidic analytes and phenols. The highest column efficiency was 2.70×10 5 platesm -1 (theoretical plates, N) for toluene. A relatively strong electroosmotic flow (EOF) was obtained in a wide range of pH values from 2.0 to 12.0, which could successfully achieve the rapid separation of the analytes within 10min. The proposed monolithic column was characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). The results indicated that the resultant monolithic column had good permeability and excellent mechanical stability. Good reproducibility was obtained with relative standard deviations (RSDs) of the retention time in the range of 0.24-0.47% and 0.81-2.17% for run-to-run (n=5) and day-to-day (n=5), while 1.09-2.70% and 0.98-1.70% for column-to-column (n=3) and batch-to-batch (n=3), respectively. The combination of AlMeIm + Cl - and styrene was a promising option in the fabrication of the organic polymer monolithic column. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecularly imprinted-solid phase extraction combined with simultaneous derivatization and dispersive liquid-liquid microextraction for selective extraction and preconcentration of methamphetamine and ecstasy from urine samples followed by gas chromatography.

PubMed

Djozan, Djavanshir; Farajzadeh, Mir Ali; Sorouraddin, Saeed Mohammad; Baheri, Tahmineh

2012-07-27

In this study, a developed technique was reported for extraction and pre-concentration of methamphetamine (MAMP) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) from urine samples using molecularly imprinted-solid phase extraction (MISPE) along with simultaneous derivatization and dispersive liquid-liquid microextraction (DLLME). Molecularly imprinted microspheres as sorbent in solid phase extraction (SPE) procedure were synthesized using precipitation polymerization with MAMP as the template. Aqueous solution of the target analytes was passed through MAMP-MIP cartridge and the adsorbed analytes were then eluted with methanol. The collected eluate was mixed with butylchloroformate which served as the derivatization reagent as well as the extraction solvent. The mixture was immediately injected into deionized water. After centrifugation, 1 μL of the settled organic phase was injected into gas chromatography-flame ionization detection (GC-FID) or gas chromatography-mass spectrometry (GC-MS). Various experimental parameters affecting the performance of both of the steps (MISPE and DLLME) were thoroughly investigated. The calibration graphs were linear in the ranges of 10-1500 ng mL(-1) (MAMP) and 50-1500 ng mL(-1) (MDMA), and the detection limits (LODs) were 2 and 18 ng mL(-1), respectively. The relative standard deviations (%RSDs) obtained for six repeated experiments (100 ng mL(-1) of each drug) were 5.1% and 6.8% for MAMP and MDMA, respectively. The relative recoveries obtained for the analytes in human urine samples, spiked with different levels of each drug, were within the range of 80-88%. Copyright © 2012 Elsevier B.V. All rights reserved.

Nanocoating cellulose paper based microextraction combined with nanospray mass spectrometry for rapid and facile quantitation of ribonucleosides in human urine.

PubMed

Wan, Lingzhong; Zhu, Haijing; Guan, Yafeng; Huang, Guangming

2017-07-01

A rapid and facile analytical method for quantification of ribonucleosides in human urine was developed by the combination of nanocoating cellulose paper based microextraction and nanoelectrospray ionization-tandem mass spectrometry (nESI-MS/MS). Cellulose paper used for microextraction was modified by nano-precision deposition of uniform ultrathin zirconia gel film using a sol-gel process. Due to the large surface area of the cellulose paper and the strong affinity between zirconia and the cis-diol compounds, the target analytes were selectively extracted from the complex matrix. Thus, the detection sensitivity was greatly improved. Typically, the nanocoating cellulose paper was immersed into the diluted urine for selective extraction of target analytes, then the extracted analytes were subjected to nESI-MS/MS detection. The whole analytical procedure could be completed within 10min. The method was evaluated by the determination of ribonucleosides (adenosine, cytidine, uridine, guanosine) in urine sample. The signal intensities of the ribonuclesides extracted by the nanocoating cellulose paper were greatly enhanced by 136-459-folds compared with the one of the unmodified cellulose paper based microextraction. The limits of detection (LODs) and the limits of quantification (LOQs) of the four ribonucleosides were in the range of 0.0136-1.258μgL -1 and 0.0454-4.194μgL -1 , respectively. The recoveries of the target nucleosides from spiked human urine were in the range of 75.64-103.49% with the relative standard deviations (RSDs) less than 9.36%. The results demonstrate the potential of the proposed method for rapid and facile determination of endogenous ribonucleosides in urine sample. Copyright © 2017. Published by Elsevier B.V.

Development of hyperbranched polymers with non-covalent interactions for extraction and determination of aflatoxins in cereal samples.

PubMed

Liu, Xiaoyan; Li, Huihui; Xu, Zhigang; Peng, Jialin; Zhu, Shuqiang; Zhang, Haixia

2013-10-03

A novel approach for assembling homogeneous hyperbranched polymers based on non-covalent interactions with aflatoxins was developed; the polymers were used to evaluate the extraction of aflatoxins B1, B2, G1 and G2 (AFB1, AFB2, AFG1 and AFG2) in simulant solutions. The results showed that the extraction efficiencies of three kinds of synthesized polymers for the investigated analytes were not statistically different; as a consequence, one of the representative polymers (polymer I) was used as the solid-phase extraction (SPE) sorbent to evaluate the influences of various parameters, such as desorption conditions, pH, ionic strength, concentration of methanol in sample solutions, and the mass of the sorbent on the extraction efficiency. In addition, the extraction efficiencies for these aflatoxins were compared between the investigated polymer and the traditional sorbent C18. The results showed that the investigated polymer had superior extraction efficiencies. Subsequently, the proposed polymer for the SPE packing material was employed to enrich and analyze four aflatoxins in the cereal powder samples. The limits of detection (LODs) at a signal-to-noise (S/N) ratio of 3 were in the range of 0.012-0.120 ng g(-1) for four aflatoxins, and the limits of quantification (LOQs) calculated at S/N=10 were from 0.04 to 0.40 ng g(-1) for four aflatoxins. The recoveries of four aflatoxins from cereal powder samples were in the range of 82.7-103% with relative standard deviations (RSDs) lower than 10%. The results demonstrate the suitability of the SPE approach for the analysis of trace aflatoxins in cereal powder samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Coupling frontal elution paper chromatography with desorption corona beam ionization mass spectrometry for rapid analysis of chlorphenamine in herbal medicines and dietary supplements.

PubMed

Huang, Yun-Qing; You, Jing-Qing; Zhang, Junsheng; Sun, Wenjian; Ding, Li; Feng, Yu-Qi

2011-10-14

We developed a convenient method by coupling frontal elution paper chromatography with desorption corona beam ionization mass spectrometry (DCBI-MS) for rapid determination of chlorphenamine added in herbal medicines or dietary supplements. In this method, the ethanol extract of the herbal products was spotted directly onto an isosceles triangular filter paper sheet, and then the paper sheet was developed under strong elution condition with the sample zone migrating at the solvent front. The analyte was finally condensed at the V-shaped tip which could then be placed under the visible plasma beam of DCBI for ionization. The overall procedure took less than 5 min. The frontal elution paper chromatography on a triangular plate used in this work improved the signal intensity of chlorphenamine by 30-fold due to the analyte condensing at the tip and the reduction of the background suppression. Furthermore, the paper sheet also functioned as a filter in the analysis of solid or powder samples, which can increase the analytical throughput by omitting the step of centrifugation. The proposed method in current study was successfully applied in the determination of chlorphenamine in herbal medicines. Chlorphenamine was detected in four of the twelve types of herbal medicines examined in this study. The limit of detection was 200 ng/mL (2.0 ng absolute) in full-scan positive-ion mode and the linear range was from 5.0 μg/mL to 50 μg/mL with satisfactory linear coefficient (R(2) (the square of the correlation coefficient)=0.895). Good reproducibility was achieved with relative standard deviations (RSDs) less than 15.0% and the recoveries of chlorphenamine ranged from 84.3 to 90.6%. Copyright © 2011 Elsevier B.V. All rights reserved.

[Determination of phthalate plasticizers in foods by high performance liquid chromatography with gel permeation chromatographic clean-up].

PubMed

Zhang, Chunyu; Wang, Hui; Zhang, Xiaohui; Ma, Zhongqiang; Deng, Wanmei; Hu, Ke; Ding, Mingyu

2011-12-01

A method of gel permeation chromatography-high performance liquid chromatography (GPC-HPLC) was established for the simultaneous determination of 5 main phthalate plasticizers in foods (edible oil, instant noodles, fried pastries, Saqima, etc.). The samples were extracted with petroleum ether in an ultrasonator, purified by a GPC column, and analyzed by HPLC. The chromatographic separation was achieved on a Labtech-C18 column (250 mm x 4.6 mm, 5 microm) using acetonitrile and water mixture as the mobile phases in a gradient elution mode. The developed method exhibited a linear correlation coefficient of more than 0.997 and the detection limits of 3.25 - 13.4 microg/L. The spike recoveries were between 70.4% and 113.6% with the relative standard deviations (RSDs, n = 3) of 0.3% - 5.8% at the spiked level of 50 mg/L. This method is simple, rapid and practical, and can be used for the simultaneous determination of PAEs in grease food samples.

Fast determination of pyrethroid pesticides in tobacco by GC-MS-SIM coupled with modified QuEChERS sample preparation procedure.

PubMed

Gao, Yan; Sun, Ying; Jiang, Chunzhu; Yu, Xi; Wang, Yuanpeng; Zhang, Hanqi; Song, Daqian

2013-01-01

An analytical method was developed for the extraction and determination of pyrethroid pesticide residues in tobacco. The modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was applied for preparing samples. In this study, methyl cyanide (MeCN)-saturated salt aqueous was used as the two-phase extraction solvent for the first time, and a vortex shaker was used for the simultaneous shaking and concentration of the analytes. The effects of experimental parameters on extraction and clean-up efficiency were investigated and optimized. The analytes were determined by gas chromatography-mass spectrometry-selected ion monitoring (GC-MS-SIM). The obtained recoveries of the analytes at three different fortification levels were 76.85-114.1% and relative standard deviations (RSDs) were lower than 15.7%. The limits of quantification (LOQs) were from 1.28 to 26.6 μg kg(-1). This method was also applied to the analysis of actual commercial tobacco products and the analytical results were satisfactory.

Analysis of processing contaminants in edible oils. Part 1. Liquid chromatography-tandem mass spectrometry method for the direct detection of 3-monochloropropanediol monoesters and glycidyl esters.

PubMed

MacMahon, Shaun; Mazzola, Eugene; Begley, Timothy H; Diachenko, Gregory W

2013-05-22

A new analytical method has been developed and validated for the detection of glycidyl esters (GEs) and 3-monochloropropanediol (3-MCPD) monoesters in edible oils. The target compounds represent two classes of potentially carcinogenic chemical contaminants formed during the processing of edible oils. Target analytes are separated from edible oil matrices using a two-step solid-phase extraction (SPE) procedure. The extracts are then analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). Chromatographic conditions that separate sn-1 and sn-2 monoesters of 3-MCPD have been developed for the first time. The method has been validated for GEs, sn-1 3-MCPD monoesters of lauric, myristic, linolenic, linoleic, oleic, and stearic acids, and sn-2 3-MCPD monoesters of oleic and palmitic acids in coconut, olive, and palm oils using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 84-115% (3-16% RSD) for the GEs, 95-113% (1-10% RSD) for the sn-1 3-MCPD monoesters, and 76.8-103% (5.1-11.2% RSD) for the sn-2 3-MCPD monoesters, with limits of quantitation at or below 30 ng/g for the GEs, 60 ng/g for sn-1 3-MCPD monoesters, and 180 ng/g for sn-2 3-MCPD monoesters.

Analysis of plant hormones by microemulsion electrokinetic capillary chromatography coupled with on-line large volume sample stacking.

PubMed

Chen, Zongbao; Lin, Zian; Zhang, Lin; Cai, Yan; Zhang, Lan

2012-04-07

A novel method of microemulsion electrokinetic capillary chromatography (MEEKC) coupled with on-line large volume sample stacking was developed for the analysis of six plant hormones including indole-3-acetic acid, indole-3-butyric acid, indole-3-propionic acid, 1-naphthaleneacetic acid, abscisic acid and salicylic acid. Baseline separation of six plant hormones was achieved within 10 min by using the microemulsion background electrolyte containing a 97.2% (w/w) 10 mM borate buffer at pH 9.2, 1.0% (w/w) ethyl acetate as oil droplets, 0.6% (w/w) sodium dodecyl sulphate as surfactant and 1.2% (w/w) 1-butanol as cosurfactant. In addition, an on-line concentration method based on a large volume sample stacking technique and multiple wavelength detection was adopted for improving the detection sensitivity in order to determine trace level hormones in a real sample. The optimal method provided about 50-100 fold increase in detection sensitivity compared with a single MEEKC method, and the detection limits (S/N = 3) were between 0.005 and 0.02 μg mL(-1). The proposed method was simple, rapid and sensitive and could be applied to the determination of six plant hormones in spiked water samples, tobacco leaves and 1-naphthylacetic acid in leaf fertilizer. The recoveries ranged from 76.0% to 119.1%, and good reproducibilities were obtained with relative standard deviations (RSDs) less than 6.6%.

Chemical fingerprint and simultaneous determination of alkaloids and flavonoids in aerial parts of genus Peganum indigenous to China based on HPLC-UV: application of analysis on secondary metabolites accumulation.

PubMed

Wen, Fangfang; Cheng, Xuemei; Liu, Wei; Xuan, Min; Zhang, Lei; Zhao, Xin; Shan, Meng; Li, Yan; Teng, Liang; Wang, Zhengtao; Wang, Changhong

2014-12-01

The aerial parts of genus Peganum are officially used in traditional Chinese medicine. The paper aims to establish a high-performance liquid chromatography (HPLC) method for fingerprint analysis and simultaneous determination of three alkaloids and two flavonoids in aerial parts of genus Peganum, and to analyze accumulative difference of secondary metabolites in inter-species, individuals of plants, inter-/intra-population and from different growing seasons. HPLC analysis was performed on a C18 column with gradient elution using 0.1% trifloroacetic acid and acetonitrile as mobile phase and detected at 265 nm, by conventional methodology validation. For fingerprint analysis, the RSDs of relative retention time and relative peak area of the characteristic peaks were within 0.07-0.78 and 0.94-9.09%, respectively. For simultaneous determination of vasicine, harmaline, harmine, deacetylpeganetin and peganetin, all calibration curves showed good linearity (r > 0.9990) within the test range. The relative standard deviations of precision, repeatability and stability test did not exceed 2.37, 2.68 and 2.67%, respectively. The average recoveries for the five analytes were between 96.47 and 101.20%. HPLC fingerprints play a minor role in authenticating and differentiating the herbs of different species of genus Peganum. However, the secondary metabolites levels of alkaloids and flavonoids in aerial parts of genus Peganum rely on species-, habitat-, and growth season-dependent accumulation. Copyright © 2014 John Wiley & Sons, Ltd.

[Simultaneous determination of 16 flavonoids in the ginkgo dietary supplement tea by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Jiang, Yalan; Huang, Fang; Wu, Fuhai; Wu, Huiqin; Huang, Xiaolan; Deng, Xin

2015-10-01

A method for the determination of 16 functional components of ginkgo dietary supplement tea such as catechin, vitexin, puerarin, isoflavoues aglycone, silymarin, quercetin, luteolin, apigenin, naringenin, hesperitin dihydrochalcone, kaempferol, hesperitin, isorhamnetin, baicalein, nobiletin and tangeretin by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was proposed. The conditions of chromatography and mass spectrometry were optimized. The 16 flavonoids were separated on a C18 chromatographic column with acetonitrile and water (additional 0.1% formic acid) as mobile phases under gradient elution at a flow rate of 0.25 mL/min. The determination was conducted by tandem mass spectrometry in positive ESI mode under multiple reaction monitoring (MRM) mode. Good linearities for all the compounds, with correlation coefficients over 0.996, were acquired. The recoveries were in the range of 70.9% to 100.0% (n = 6), while the relative standard deviations (RSDs) were less than 10%. The results showed that the nine flavonoids, which were kaempferol, quercetin, hesperitin, vitexin, luteolin, catechin, apigenin, naringenin and isorhamnetin, were higher in contents among the 16 flavonoids in real samples, and they constituted up to 99.6% of the total flavonoids. The contents of these nine flavonoids can be considered as the quality control index of the ginkgo dietary supplement tea. The method proved to be rapid, selective, sensitive and stable, and it can be applied to control the quality of the ginkgo dietary supplement tea.

Dissipation kinetics of emamectin benzoate and lufenuron residues in cabbage grown under field conditions.

PubMed

Dong, Bizhang; Zhao, Qing; Hu, Jiye

2015-12-01

Residue analysis of emamectin benzoate and lufenuron in cabbage matrices and soil was developed using a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and ultra high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The samples were extracted with 1% acetic acid in acetonitrile (v/v) or 1% acetic acid in acetonitrile/water (5:1, v/v) and cleaned up by dispersive solid-phase extraction. Mean recoveries and relative standard deviations (RSDs) in all samples ranged 87.8-100.0 % and 3.6-12.6% for emamectin benzoate and 87.8-104.8 % and 6.2-11.5% for lufenuron, respectively. The validated method was used to evaluate the dissipation rate of emamectin benzoate and lufenuron in cabbage and soil as well as the residual levels in harvested cabbage and soil at different preharvest intervals (PHI). The half-lives of emamectin benzoate and lufenuron were 1.08-2.70 and 1.74-5.04 days in cabbage, and 1.42-4.01 and 0.94-6.18 days in soil, respectively. The terminal residues were below the China maximum residue limits (MRLs) at 3 days for emamectin benzoate (0.1 mg kg(-1)) and European Union MRLs at 5 days for lufenuron (0.5 mg kg(-1)), which suggested that 5 days could be recommended as the PHI for the commercial formulation of emamectin benzoate and lufenuron application in the Chinese cabbage field.

Preparation of an aminopropyl imidazole-modified silica gel as a sorbent for solid-phase extraction of carboxylic acid compounds and polycyclic aromatic hydrocarbons.

PubMed

Wang, Na; Guo, Yong; Wang, Licheng; Liang, Xiaojing; Liu, Shujuan; Jiang, Shengxiang

2014-05-21

In this paper, a kind of aminopropyl imidazole-modified silica sorbent was synthesized and used as a solid-phase extraction (SPE) sorbent for the determination of carboxylic acid compounds and polycyclic aromatic hydrocarbons (PAHs). The resultant aminopropyl imidazole-modified silica sorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA) to ensure the successful binding of aminopropyl imidazole on the surface of silica gel. Then the aminopropyl imidazole-modified silica sorbent served as a SPE sorbent for the enrichment of carboxylic acid compounds and PAHs. The new sorbent exhibited high extraction efficiency towards the tested compounds and the results show that such a sorbent can offer multiple intermolecular interactions: electrostatic, π-π, and hydrophobic interactions. Several parameters affecting the extraction recovery, such as the pH of sample solution, the pH of eluent, the solubility of eluent, the volume of eluent, and sample loading, were also investigated. Under the optimized conditions, the proposed method was applied to the analysis of four carboxylic acid compounds and four PAHs in environmental water samples. Good linearities were obtained for all the tested compounds with R(2) larger than 0.9903. The limits of detection were found to be in the range of 0.0065-0.5 μg L(-1). The recovery values of spiked river water samples were from 63.2% to 112.3% with relative standard deviations (RSDs) less than 10.1% (n = 4).

[Determination of geniposidic acid and chlorogenic acid in male flowers and related products of Eucommia ulmoides by reversed-phase high performance liquid chromatography].

PubMed

Dong, Juane; Ma, Xihan

2007-03-01

A simple and rapid high performance liquid chromatographic method has been developed for the determination of geniposidic acid and chlorogenic acid in the male flowers and related products of Eucommia ulmoides. Two components were separated by a Shim-pack VP-ODS column (150 mm x4.6 mm, 5 [microm) with a mobile phase of methanol-water-acetic acid (24 :75: 1, v/v) at a flow rate of 1 mL/min, column temperature of 30 93 and detection wavelength of 240 nm. Under the chromatographic conditions mentioned above, the method performance, such as the number of theoretical plate, resolution, trailing etc have all reached required level. The linear ranges were 0. 025 - 0. 400 g/L for geniposidic acid and 0. 075 - 1. 200 g/L for chlorogenic acid, with the correlation coefficients of 0. 999 7 and 0. 999 9, respectively. The average recoveries were 100. 2% and 100. 5%, and the relative standard deviations (RSDs) were 1. 47% and 1. 49% respectively. The minimum detection limits were 0. 02 microg/L for geniposidic acid, and 0. 06 microg/L for chlorogenic acid. The method developed has demonstrated the characteristics of simple mobile phase composition, short retention, good resolution, high repeatability and precision. It is suitable for the determination of the two compounds in the male flowers of E. ulmoides and related products.

Dual-cloud point extraction coupled to high performance liquid chromatography for simultaneous determination of trace sulfonamide antimicrobials in urine and water samples.

PubMed

Nong, Chunyan; Niu, Zongliang; Li, Pengyao; Wang, Chunping; Li, Wanyu; Wen, Yingying

2017-04-15

Dual-cloud point extraction (dCPE) was successfully developed for simultaneous extraction of trace sulfonamides (SAs) including sulfamerazine (SMZ), sulfadoxin (SDX), sulfathiazole (STZ) in urine and water samples. Several parameters affecting the extraction were optimized, such as sample pH, concentration of Triton X-114, extraction temperature and time, centrifugation rate and time, back-extraction solution pH, back-extraction temperature and time, back-extraction centrifugation rate and time. High performance liquid chromatography (HPLC) was applied for the SAs analysis. Under the optimum extraction and detection conditions, successful separation of the SAs was achieved within 9min, and excellent analytical performances were attained. Good linear relationships (R 2 ≥0.9990) between peak area and concentration for SMZ and STZ were optimized from 0.02 to 10μg/mL, for SDX from 0.01 to 10μg/mL. Detection limits of 3.0-6.2ng/mL were achieved. Satisfactory recoveries ranging from 85 to 108% were determined with urine, lake and tap water spiked at 0.2, 0.5 and 1μg/mL, respectively, with relative standard deviations (RSDs, n=6) of 1.5-7.7%. This method was demonstrated to be convenient, rapid, cost-effective and environmentally benign, and could be used as an alternative tool to existing methods for analysing trace residues of SAs in urine and water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Magnetic immunoassay coupled with inductively coupled plasma mass spectrometry for simultaneous quantification of alpha-fetoprotein and carcinoembryonic antigen in human serum

NASA Astrophysics Data System (ADS)

Zhang, Xing; Chen, Beibei; He, Man; Zhang, Yiwen; Xiao, Guangyang; Hu, Bin

2015-04-01

The absolute quantification of glycoproteins in complex biological samples is a challenge and of great significance. Herein, 4-mercaptophenylboronic acid functionalized magnetic beads were prepared to selectively capture glycoproteins, while antibody conjugated gold and silver nanoparticles were synthesized as element tags to label two different glycoproteins. Based on that, a new approach of magnetic immunoassay-inductively coupled plasma mass spectrometry (ICP-MS) was established for simultaneous quantitative analysis of glycoproteins. Taking biomarkers of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) as two model glycoproteins, experimental parameters involved in the immunoassay procedure were carefully optimized and analytical performance of the proposed method was evaluated. The limits of detection (LODs) for AFP and CEA were 0.086 μg L- 1 and 0.054 μg L- 1 with the relative standard deviations (RSDs, n = 7, c = 5 μg L- 1) of 6.5% and 6.2% for AFP and CEA, respectively. Linear range for both AFP and CEA was 0.2-50 μg L- 1. To validate the applicability of the proposed method, human serum samples were analyzed, and the obtained results were in good agreement with that obtained by the clinical chemiluminescence immunoassay. The developed method exhibited good selectivity and sensitivity for the simultaneous determination of AFP and CEA, and extended the applicability of metal nanoparticle tags based on ICP-MS methodology in multiple glycoprotein quantifications.

[Determination of acetanilide herbicide residues in tea by gas chromatography-mass spectrometry with two different ionization techniques].

PubMed

Shen, Weijian; Xu, Jinzhong; Yang, Wenquan; Shen, Chongyu; Zhao, Zengyun; Ding, Tao; Wu, Bin

2007-09-01

An analytical method of solid phase extraction-gas chromatography-mass spectrometry with two different ionization techniques was established for simultaneous determination of 12 acetanilide herbicide residues in tea-leaves. Herbicides were extracted from tea-leaf samples with ethyl acetate. The extract was cleaned-up on an active carbon SPE column connected to a Florisil SPE column. Analytical screening was determined by the technique of gas chromatography (GC)-mass spectrometry (MS) in the selected ion monitoring (SIM) mode with either electron impact ionization (EI) or negative chemical ionization (NCI). It is reliable and stable that the recoveries of all herbicides were in the range from 50% to 110% at three spiked levels, 10 microg/kg, 20 microg/kg and 40 microg/kg, and the relative standard deviations (RSDs) were no more than 10.9%. The two different ionization techniques are complementary as more ion fragmentation information can be obtained from the EI mode while more molecular ion information from the NCI mode. By comparison of the two techniques, the selectivity of NCI-SIM was much better than that of EI-SIM method. The sensitivities of the both techniques were high, the limit of quantitative (LOQ) for each herbicide was no more than 2.0 microg/kg, and the limit of detection (LOD) with NCI-SIM technique was much lower than that of EI-SIM when analyzing herbicides with several halogen atoms in the molecule.

On-line high-performance liquid chromatography-ultraviolet-nuclear magnetic resonance method of the markers of nerve agents for verification of the Chemical Weapons Convention.

PubMed

Mazumder, Avik; Gupta, Hemendra K; Garg, Prabhat; Jain, Rajeev; Dubey, Devendra K

2009-07-03

This paper details an on-flow liquid chromatography-ultraviolet-nuclear magnetic resonance (LC-UV-NMR) method for the retrospective detection and identification of alkyl alkylphosphonic acids (AAPAs) and alkylphosphonic acids (APAs), the markers of the toxic nerve agents for verification of the Chemical Weapons Convention (CWC). Initially, the LC-UV-NMR parameters were optimized for benzyl derivatives of the APAs and AAPAs. The optimized parameters include stationary phase C(18), mobile phase methanol:water 78:22 (v/v), UV detection at 268nm and (1)H NMR acquisition conditions. The protocol described herein allowed the detection of analytes through acquisition of high quality NMR spectra from the aqueous solution of the APAs and AAPAs with high concentrations of interfering background chemicals which have been removed by preceding sample preparation. The reported standard deviation for the quantification is related to the UV detector which showed relative standard deviations (RSDs) for quantification within +/-1.1%, while lower limit of detection upto 16mug (in mug absolute) for the NMR detector. Finally the developed LC-UV-NMR method was applied to identify the APAs and AAPAs in real water samples, consequent to solid phase extraction and derivatization. The method is fast (total experiment time approximately 2h), sensitive, rugged and efficient.

Validation of a rapid micellar electrokinetic capillary chromatographic method for the simultaneous determination of isoniazid and pyridoxine hydrochloride in pharmaceutical formulation.

PubMed

Nemutlu, E; Celebier, M; Uyar, B; Altinöz, S

2007-07-01

An efficient and reliable micellar electrokinetic capillary chromatography (MEKC) method has been developed for the simultaneous determination of isoniazid (ISO) and pyridoxine hydrochloride (PYR) in pharmaceutical formulations. A chemometric two level full factorial design approach was used to search for the optimum conditions of separation. Three parameters were selected for this study: the buffer pH, the buffer concentration and sodium dodecyl sulphate (SDS) concentrations. Resolution, peak symmetry and analysis time were established as response. The two analytes were separated within 6 min with the optimized conditions: 50 mM borate buffer, 25 mM SDS pH 7.8, 35 degrees C, at 50 mbar 4s injection and 30 kV by using a fused silica capillary (72 cm effective length, 50 microm i.d.). The detection wavelength was set to 205 nm. Meloxicam was used as internal standard. The method was validated with respect to stability, linearity range, limit of quantitation and detection, precision, accuracy, specificity and robustness. The detection limits of the method were 1.0 microg mL(-1) for ISO and 0.40 microg mL(-1) for PYR and the method was linear at least in the range of 3.0-100 microg mL(-1) for ISO and 1.0-100 microg mL(-1) for PYR with excellent correlation coefficients (0.9995 for ISO and 0.9998 for PYR). Relative standard deviations (R.S.D.s) of the described method ranged between 0.54 and 2.27% for intra-day precision and between 0.65 and 2.69% for inter-day precision. The developed method was applied to the tablet form of ISO and PYR-containing the pharmaceutical preparations and the data were compared with obtained from the standard addition method. No statistically significant difference was found.

Fast, sensitive and reliable multi-residue method for routine determination of 34 pesticides from various chemical groups in water samples by using dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry.

PubMed

Tankiewicz, Maciej; Biziuk, Marek

2018-02-01

A simple and efficient dispersive liquid-liquid microextraction technique (DLLME) was developed by using a mixture of two solvents: 40 μL of tetrachlorethylene (extraction solvent) and 1.0 mL of methanol (disperser solvent), which was rapidly injected with a syringe into 10 mL of water sample. Some important parameters affecting the extraction efficiency, such as type and volume of solvents, water sample volume, extraction time, temperature, pH adjustment and salt addition effect were investigated. Simultaneous determination of 34 commonly used pesticides was performed by using gas chromatography coupled with mass spectrometry (GC-MS). The procedure has been validated in order to obtain the highest efficiency at the lowest concentration levels of analytes to fulfill the requirements of regulations on maximum residue limits. Under the optimum conditions, the linearity range was within 0.0096-100 μg L -1 . The limits of detection (LODs) of the developed DLLME-GC-MS methodology for all investigated pesticides were in the range of 0.0032 (endrin)-0.0174 (diazinon) μg L -1 and limits of quantification (LOQs) from 0.0096 to 0.052 μg L -1 . At lower concentration of 1 μg L -1 for each pesticide, recoveries ranged between 84% (tebufenpyrad) and 108% (deltamethrin) with relative standard deviations (RSDs) (n = 7) from 1.1% (metconazole) to 11% (parathion-mehtyl). This methodology was successfully applied to check contamination of environmental samples. The procedure has proved to be selective, sensitive and precise for the simultaneous determination of various pesticides. The optimized analytical method is very simple and rapid (less than 5 min). Graphical abstract Analytical procedure for testing water samples consists of dispersive liquid-liquid microextraction (DLLME) and gas chromatography coupled with mass spectrometry (GC-MS).

Performance comparison of hybrid resistive switching devices based on solution-processable nanocomposites

NASA Astrophysics Data System (ADS)

Rajan, Krishna; Roppolo, Ignazio; Bejtka, Katarzyna; Chiappone, Annalisa; Bocchini, Sergio; Perrone, Denis; Pirri, Candido Fabrizio; Ricciardi, Carlo; Chiolerio, Alessandro

2018-06-01

The present work compares the influence of different polymer matrices on the performance of planar asymmetric Resistive Switching Devices (RSDs) based on silver nitrate and Ionic Liquid (IL). PolyVinyliDene Fluoride-HexaFluoroPropylene (PVDF-HFP), PolyEthylene Oxide (PEO), PolyMethyl MethAcrylate (PMMA) and a blend of PVDF-HFP and PEO were used as matrices and compared. RSDs represent perhaps the most promising electron device to back the More than Moore development, and our approach through functional polymers enables low temperature processing and gives compatibility towards flexible/stretchable/wearable equipment. The switching mechanism in all the four sample families is explained by means of a filamentary conduction. A huge difference in the cyclability and the On/Off ratio is experienced when changing the active polymers and explained based on the polymer crystallinity degree and general morphology of the prepared nanocomposite. It is worth noting that all the RSDs discussed here present good switching behaviour with reasonable endurance. The current study displays one of the most cost-effective and effortless ways to produce an RSD based on solution-processable materials.

Pesticide analysis in coffee leaves using a quick, easy, cheap, effective, rugged and safe approach and liquid chromatography tandem mass spectrometry: Optimization of the clean-up step.

PubMed

Trevisan, Maria Teresa Salles; Owen, Robert Wyn; Calatayud-Vernich, Pau; Breuer, Andrea; Picó, Yolanda

2017-08-25

An analytical method using a quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure for multi-residue determination of 52 pesticides in coffee leaf extractshas been developed and validated according to SANTE/11945/2015 guidelines. Different sorbent combinations for dispersive solid phase extraction (d-SPE) clean-up as well as dispersive liquid-liquid microextraction (DLLME) were tested. The relative standard deviations (RSDs) for the recovery of 87-94% of pesticides added to coffee leaf extracts,was ≤20% for samples spiked at concentrations up to 50ng*g -1 depending on the clean-up procedures. However, samples spiked with a 100ng*g -1 pesticide mixture gave RSDs>20% for most pesticides when d-SPE was carried out adding Supelclean ENVI-Carb 120/400. To explain this fact,the secondary metabolic profile was analyzed in all the extraction and clean-up procedures. Only in the clean-up procedure with the addition of Supel QuE Z-Sep+, does caffeine show a constant adsorption between blank and spiked samples. In other clean-up procedures, the amount of caffeine was higher in those samples spiked with pesticides. This indicates competition between caffeine and pesticides for adsorption to the sorbent. Addition of Supel QuE Z-Sep+ to the procedure revealed only a 32% matrix effect, whereas using PSA+ C18 the matrix effect was close to 97%. The process efficiency is up to 54% with the addition of Supel QuE Z-Sep+ and just up to 7% for the other clean-up procedures. The method was successfully tested in coffee leaves from different types of cultivars. Pesticides were not detected in organic coffee leaf extracts, but thiametoxan was clearly detected in 50% of coffee leaf extracts harvested from coffee trees grown under traditional conditions as determined by UHPLC-TOFMSLC/QqTOF-MS/MS. Copyright © 2017 Elsevier B.V. All rights reserved.

Repeatability of the efficiency of columns packed with sub-3μm core-shell particles: Part II. 2.7 μm Halo-ES-Peptide-C18 particles in 4.6mm and 2.1mm×100mm column formats.

PubMed

Gritti, Fabrice; Guiochon, Georges

2012-08-24

The column-to-column repeatability of the mass transfer kinetics in columns packed with sub-3μm shell particles was investigated. The parameters of this kinetics were measured for twelve columns (six 2.1mm×100mm and six 4.6mm×100mm) packed with the same batch of 2.7μm Halo-ES-Peptide-C(18) particles (Advanced Material Technologies, Wilmington, DE, USA). For both series, the manufacturer provided columns at different positions in the efficiency distribution given by the quality test control. Three compounds were used, uracil, naphthalene and insulin. The reduced longitudinal diffusion term was measured with the peak parking (PP) method; the reduced solid-liquid mass transfer resistance term was given by a combination of the PP results and the most accurate model of effective diffusion in ternary composite materials (non-porous cores, concentric porous shell, and eluent matrix), validated previously. The overall eddy diffusion term was obtained by subtraction of these two HETP terms from the overall reduced HETP measured by numerical integration of the entire peak profiles. The results demonstrate that the dispersion of the column efficiencies is mostly due to the random nature of the packing process and the associated eddy diffusion term. At the highest reduced velocity achieved, the relative standard deviations (RSDs) of the eddy diffusion term for the 2.1mm I.D. columns were ca. 5 and 10% (with average values A(ν)=2.3 and 8.5) for naphthalene and uracil, respectively. For the 4.6mm I.D. columns, these RSDs were 3 and 5%, respectively, with average values A(ν)=1.5 and 2.7. Copyright © 2012 Elsevier B.V. All rights reserved.

A liquid chromatography method for determination of selected amino acids, coenzymes, growth regulators, and vitamins from Cicer arietinum (L.) and Solanum lycopersicum (L.).

PubMed

Meher, Hari Charan; Gajbhiye, Vijay T; Singh, Ghanendra

2012-01-01

A bottleneck in crosstalk and QC research has been the quantification of diverse chemotypes in small amounts of tissue. An LC-UV method for estimating 28 selected metabolites of the regulatory network underlying growth, development, maintenance, vital functions, defense reactions, and food quality is reported. The method was based on binary gradient resolutions of the analytes in an RP C18 column. The mobile phase comprised solvent A [water+0.1% trifluoroacetic acid (TFA)] and B (acetonitrile + 0.085% TFA at a flow rate of 1 ml/min. Twenty-three metabolites (selected amino acids, coenzymes, growth regulators, phenolic antioxidant, and water-soluble vitamins) were detected at 254 nm, and four fat-soluble vitamins at 280 nm. Jasmonic acid was quantified at 210 nm. The RSDs of peak area and retention time for each metabolite were <5.8%. The calibration graphs were linear with R2 values ranging from 0.98 to 0.99. The LODs (microg/mL) were about 0.01-1.0 for 23 metabolites quantified at 254 nm, 0.1-0.2 for fat-soluble vitamins, and 0.1 for jasmonic acid. The recoveries ranged from 80 to 105%, with RSDs of 2.8 to 11.2%. The method has been satisfactorily applied for determination of 28 metabolites from Cicer arietinum (L.) and Solanum lycopersicum (L.). It could be an alternative and competitive method of choice that can cheaply and easily perform routine analysis for food quality and targeted metabolomics of chickpea and tomato in response to stressors.

Site Survey of the Martha's Vineyard Coastal Observatory: Backscatter, Grain Size and Temporal Evolution of Rippled Scour Depressions

NASA Astrophysics Data System (ADS)

Goff, J. A.; Mayer, L.; Schwab, B.; Traykovski, P.; Wilkins, R.; Jenkins, C.; Kraft, B.; Evans, R.; Buynevich, I.

2002-12-01

The Office of Naval Research's Mine Burial Prediction program has chosen the Martha's Vineyard Coastal Observatory (MVCO) as a natural laboratory for experimental observations of object burial by nearshore processes (e.g., bedform migration, scour). In support of this program, the MVCO has been subject to an intensive site survey program, involving, since early 2001: (1) three swath backscatter and/or bathymetry surveys; (2) three high resolution seismic surveys; (3) ultra-high resolution sector-scanning sonar on pole mounts; (4) in situ geotechnical (velocity and resistivity) measurements, (5) grab sampling, and (6) vibracoring. These efforts are concentrated in water depths between ~8 and 18 m, centered on the site of the MVCO permanent node at ~12 m water depth Rippled scour depressions (RSDs) are pervasive within the MVCO. RSDs are ~shore-perpendicular bands of coarse sands separated by overlying fine sands. The term itself implies that the coarse sands are heavily rippled (~0.5-1 m wavelength, ~0.1 m amplitude) and slightly depressed relative to the fine sands which, in the MVCO, are generally just a few 10's of cm thick. The RSDs are clearly evident on sidescan data as bands of high backscatter. For the most part, grain size measurements confirm a strong positive correspondence between mean grain size and backscatter intensity. However, a critical exception is seen in deeper water where, well within the area of fine sands, backscatter increases noticeably as mean grain size decreases from ~150μ to ~130μ. Topographic expression related to the RSDs is confined primarily to evident scour depressions at the edges. The RSDs are highly asymmetric: backscatter is higher, the coarse/fine transition is more sharply defined, and the scour depression is deeper on one side than the other. This pattern changes within the survey: the higher backscatter edge is always to the west in the western part of the survey, and vice versa to the east. The strike of the RSDs also changes, from being slightly east of north in the western part of the survey to slightly west of north to the east. The MVCO site survey work establishes a baseline set of observations against which physical changes in the seafloor with time can be measured. Early evidence of significant change has been provided by comparison of the first two sidescan surveys, which indicates a shift in the RSD boundaries by as much as 50 m between February and September of 2001. Continued seafloor evolution is evidenced by the August 2002 grab sampling and sector scanning sonar. This dynamic setting will continue to be monitored by additional swath mapping and sampling in conjunction with the planned winter 2003/2004 mine burial experiment.

Determination of endocrine-disrupting chemicals in human milk by dispersive liquid-liquid microextraction.

PubMed

Vela-Soria, Fernando; Jiménez-Díaz, Inmaculada; Díaz, Caridad; Pérez, José; Iribarne-Durán, Luz María; Serrano-López, Laura; Arrebola, Juan Pedro; Fernández, Mariana Fátima; Olea, Nicolás

2016-09-01

Human populations are widely exposed to numerous so-called endocrine-disrupting chemicals, exogenous compounds able to interfere with the endocrine system. This exposure has been associated with several health disorders. New analytical procedures are needed for biomonitoring these xenobiotics in human matrices. A quick and inexpensive methodological procedure, based on sample treatment by dispersive liquid-liquid microextraction, is proposed for the determination of bisphenols, parabens and benzophenones in samples. LOQs ranged from 0.4 to 0.7 ng ml(-1) and RSDs from 4.3 to 14.8%. This methodology was satisfactorily applied in the simultaneous determination of a wide range of endocrine-disrupting chemicals in human milk samples and is suitable for application in biomonitoring studies.

Determination of tylosin residues in pig tissues using high-performance liquid chromatography.

PubMed

De Liguoro, M; Anfossi, P; Angeletti, R; Montesissa, C

1998-06-01

In accordance with the maximum residue limit of 100 micrograms kg-1 established by EU legislation, a simple and sensitive high-performance liquid chromatographic (HPLC) method was developed for the measurement of tylosin residues in pig tissues (fat, kidney, liver and muscle). Tylosin, a macrolide antibiotic, is extracted with water-methanol and cleaned-up by solid-phase extraction (SPE) on cation-exchange cartridges using methanol elution. Tylosin was determined by reversed-phase HPLC with UV detection at 280 nm and the mean recovery from pig tissues fortified in the range 50-200 micrograms kg-1 was 70-85%, with intra- and inter-day RSDs in the ranges 3.4-9.1 and 3.9-10.1% respectively.

Diagnostic value of thallium-201 myocardial perfusion IQ-SPECT without and with computed tomography-based attenuation correction to predict clinically significant and insignificant fractional flow reserve

PubMed Central

Tanaka, Haruki; Takahashi, Teruyuki; Ohashi, Norihiko; Tanaka, Koichi; Okada, Takenori; Kihara, Yasuki

2017-01-01

Abstract The aim of this study was to clarify the predictive value of fractional flow reserve (FFR) determined by myocardial perfusion imaging (MPI) using thallium (Tl)-201 IQ-SPECT without and with computed tomography-based attenuation correction (CT-AC) for patients with stable coronary artery disease (CAD). We assessed 212 angiographically identified diseased vessels using adenosine-stress Tl-201 MPI-IQ-SPECT/CT in 84 consecutive, prospectively identified patients with stable CAD. We compared the FFR in 136 of the 212 diseased vessels using visual semiquantitative interpretations of corresponding territories on MPI-IQ-SPECT images without and with CT-AC. FFR inversely correlated most accurately with regional summed difference scores (rSDS) in images without and with CT-AC (r = −0.584 and r = −0.568, respectively, both P < .001). Receiver-operating characteristics analyses using rSDS revealed an optimal FFR cut-off of <0.80 without and with CT-AC. Although the diagnostic accuracy of FFR <0.80 did not significantly differ, FFR ≥0.82 was significantly more accurate with, than without CT-AC. Regions with rSDS ≥2 without or with CT-AC predicted FFR <0.80, and those with rSDS ≤1 without and with CT-AC predicted FFR ≥0.81, with 73% and 83% sensitivity, 84% and 67% specificity, and 79% and 75% accuracy, respectively. Although limited by the sample size and the single-center design, these findings showed that the IQ-SPECT system can predict FFR at an optimal cut-off of <0.80, and we propose a novel application of CT-AC to MPI-IQ-SPECT for predicting clinically significant and insignificant FFR even in nonobese patients. PMID:29390486

[Investigation on the homogeneity and stability of quality controlling cosmetic samples containing arsenic].

PubMed

Dong, Bing; Song, Yu; Fan, Wenjia; Zhu, Ying

2010-11-01

To study the homogeneity and stability of arsenic in quality controlling cosmetic samples. Arsenic was determined by atomic fluorescence spectrophotometric method. The t-test and F-test were used to evaluate the significant difference of the within-bottle and between-bottle results with three batches. The RSDs of arsenic obtained in different time were compared with the relative expanding uncertainties to evaluate the stability. Average and variance of within-bottle and between-bottle results of arsenic were not different significantly. The RSDs of Arsenic were less than the relative expanding uncertainties. Quality controlling cosmetic samples containing arsenic were considered homogeneous and stable.

Chemical profiling and quantification of Chinese medicinal formula Huang-Lian-Jie-Du decoction, a systematic quality control strategy using ultra high performance liquid chromatography combined with hybrid quadrupole-orbitrap and triple quadrupole mass spectrometers.

PubMed

Yang, Yang; Wang, Hong-Jie; Yang, Jian; Brantner, Adelheid H; Lower-Nedza, Agnieszka D; Si, Nan; Song, Jian-Fang; Bai, Bing; Zhao, Hai-Yu; Bian, Bao-Lin

2013-12-20

To clarify and quantify the chemical profiling of Huang-Lian-Jie-Du decoction (HLJDD) rapidly, a feasible and accurate strategy was developed by applying high speed LC combined with hybrid quadrupole-orbitrap mass spectrometer (Q-Exactive) and UHPLC-triple quadruple mass spectrometer (UHPLC-QqQ MS). 69 compounds, including iridoids, alkaloids, flavonoids, triterpenoid, monoterpene and phenolic acids, were identified by their characteristic high resolution mass data. Among them, 18 major compounds were unambiguously detected by comparing with reference standards. In the subsequent quantitative analysis, 17 representative compounds, selected as quality control markers, were simultaneously detected in 10 batches of HLJDD samples by UHPLC-QqQ MS. These samples were collected from four different countries (regions). Icariin, swertiamarin and corynoline were employed as internal standards for flavonoids, iridoids and alkaloids respectively. All the analytes were detected within 12min. Polarity switching mode was used in the optimization of multiple reaction monitoring (MRM) conditions. Satisfactory linearity was achieved with wide linear range and fine determination coefficient (r(2)>0.9990). The relative standard deviations (RSD) of inter- and intra-day precisions were less than 5.0%. This method was also validated by repeatability, stability (8h) and recovery, with respective RSDs less than 4.6%, 5.0% and 6.3%. This research established a high sensitive and efficient method for the integrating quality control, including identification and quantification of Chinese medicinal formulas. Copyright © 2013 Elsevier B.V. All rights reserved.

Graphene/multi-walled carbon nanotubes functionalized with an amine-terminated ionic liquid for determination of (Z)-3-(chloromethylene)-6-fluorothiochroman-4-one in urine.

PubMed

Chen, Huanhuan; Yuan, Yanan; Xiang, Can; Yan, Hongyuan; Han, Yehong; Qiao, Fengxia

2016-11-25

A new type of amine-terminated-ionic-liquid-functionalized graphene/multi-walled carbon nanotubes hybrid material (IL-G/MWCNTs) was synthesized and used as an adsorbent in miniaturized pipette tip solid-phase extraction (PT-SPE) coupled with liquid chromatography for the isolation and determination of (Z)-3-(chloromethylene)-6-fluorothiochroman-4-one (CMFT) in urine. Parameters for the preparation of IL-G/MWCNTs and the PT-SPE procedure, including the mass ratio of graphene oxide and oxidized multi-walled carbon nanotubes, the mass ratio of graphene oxide and the ionic liquid, and the type and volume of washing and elution solvents were optimized to achieve higher extraction efficiency. Good linearity of the method was achieved in the range 0.03-5.0μgmL -1 with a coefficient of determination (r 2 ) of 0.9999. The limits of detection and quantification were 0.009 and 0.030μgmL -1 , respectively. The intra- and inter-day precisions, expressed as relative standard deviations (RSDs), were evaluated by performing replicate analyses of samples spiked at 0.1μgmL -1 on the same day (n=6) and over three consecutive days, and were 4.8 and 5.5%, respectively. Recoveries between 73.9 and 93.9% were obtained at three spiking levels, with RSDs≤7.9%. Five batches of the adsorbent were investigated to confirm the reliability of the preparation method. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantification of γ-aminobutyric acid in the heads of houseflies (Musca domestica) and diamondback moths (Plutella xylostella (L.)), using capillary electrophoresis with laser-induced fluorescence detection.

PubMed

Shi, Xueyan; Liang, Pei; Song, Dunlun; Yang, Wenling; Gao, Xiwu

2012-02-01

A novel method was developed for quantifying the levels of γ-aminobutyric acid (GABA) in the heads of houseflies (Musca domestica) and diamondback moths (Plutella xylostella (L.)), using capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). The GABA in sample was derivatized with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) prior to CE-LIF analysis. In total, 32 mmol/L borate buffer, at pH 9.2 and containing 5.3 mmol/L β-cyclodextrin (β-CD) and 10.4 mmol/L sodium dodecyl sulfate (SDS), was determined to be the optimum CE background electrolyte (BGE) for GABA analysis. The detection limit of GABA was 0.016 μmol/L. The relative standard deviations (RSDs) of the migration time and peak area of GABA were 1.78 and 4.93%, respectively. The average recoveries of 0.97, 3.88, and 5.83 μmol/L of GABA, each added to the head sample of housefly, ranged from 88.9 to 110.5%. This method is simple and applicable to GABA assays of the heads of insects. With this newly developed CE-LIF method, the amounts of GABA in the heads of houseflies (M. domestica) and diamondback moths (P. xylostella (L.)) were measured. The results are relevant to the understandings of some insecticides and insecticide-resistance mechanisms in pests. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Magnetic halloysite nanotube/polyaniline/copper composite coupled with gas chromatography-mass spectrometry: A rapid approach for determination of nitro-phenanthrenes in water and soil samples.

PubMed

Darvishnejad, Mohammad; Ebrahimzadeh, Homeira

2018-08-17

A fast, sensitive and reliable ultrasound-assisted magnetic dispersive solid-phase microextraction (UAMDSPME) setup was developed and evaluated for the enrichment of nitro- phenanthrenes compound in environmental samples prior to GC-MS determination. A new type of nanocomposite sorbent was made based on halloysite nanotubes (HNTs). HNTs is a type of natural material, have attracted great interest because of their large surface area and high chemical and thermal stability. The hybrid nanocomposite (magnetic HNT@PANI@Cu) was obtained by coating the magnetic HNTs by polyaniline (PANI) and afterwards decorating with metalic copper. Its morphology and surface properties were characterized using Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, energy dispersive spectroscopy and vibrating sample magnetometry. In this work several factors that may affect the extraction efficiencies such as desorption solvent type and its volume, sonication times for extraction and desorption, sorbent amount, organic modifier content, salt concentration and matrix effect were investigated in detail. Under the optimal conditions, the limit of detection (S/N = 3) was 0.25 ng L -1 and the linearity was in the range of 0.01-100 μg L -1 . The method precision expressed as relative standard deviations (RSDs%) were 4.6-6.1% (intra-day), and 7.2-9.6% (inter-day). Finally, the presented method was successfully applied to the rapid determination of trace levels of nitro-phenanthrenes in spiked water and soil samples. Copyright © 2018 Elsevier B.V. All rights reserved.

[Target and non-target screening of volatile organic compounds in industrial exhaust gas using thermal desorption-gas chromatography-mass spectrometry].

PubMed

Ma, Huilian; Jin, Jing; Li, Yun; Chen, Jiping

2017-10-08

A method of comprehensive screening of the target and non-target volatile organic compounds (VOCs) in industrial exhaust gas using thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) has been developed. In this paper, two types of solid phase adsorption column were compared, and the Tenex SS TD Tube was selected. The analytes were enriched into the adsorption tube by constant flow sampling, and detected by TD-GC-MS in full scan mode. Target compounds were quantified by internal standard method, and the quantities of non-target compounds were calculated by response coefficient of toluene. The method detection limits (MDLs) for the 24 VOCs were 1.06 to 5.44 ng, and MDLs could also be expressed as 0.004 to 0.018 mg/m 3 assuming that the sampling volume was 300 mL. The average recoveries were in the range of 78.4% to 89.4% with the relative standard deviations (RSDs) of 3.9% to 14.4% ( n =7). The established analytical method was applied for the comprehensive screening of VOCs in a waste incineration power plant in Dalian city. Twenty-nine VOCs were identified. In these compounds, only five VOCs were the target compounds set in advance, which accounted for 26.7% of the total VOCs identified. Therefore, this study further proved the importance of screening non-target compounds in the analysis of VOCs in industrial exhaust gas, and has certain reference significance for the complete determination of VOCs distribution.

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids.

PubMed

Zheng, Xiaojiao; Qiu, Yunping; Zhong, Wei; Baxter, Sarah; Su, Mingming; Li, Qiong; Xie, Guoxiang; Ore, Brandon M; Qiao, Shanlei; Spencer, Melanie D; Zeisel, Steven H; Zhou, Zhanxiang; Zhao, Aihua; Jia, Wei

2013-08-01

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and inter-day (within 7 days) precision (< 10%), and good stability (< 20%) within 4 days at room temperature (23-25 °C), or 7 days when stored at -20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistics analysis of the concentrations of these target metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research.

Simultaneous and confirmative detection of multi-residues of β₂-agonists and β-blockers in urine using LC-MS/MS/MS coupled with β-receptor molecular imprinted polymer SPE clean-up.

PubMed

Fan, S; Zou, J H; Miao, H; Zhao, Y F; Chen, H J; Zhao, R; Wu, Y N

2013-01-01

A liquid chromatography-linear ion-trap spectrometry (LC-MS³) method using β-receptor molecular-imprinted polymer (MIP) solid-phase extraction (SPE) as clean-up was developed to determine simultaneously and confirmatively residues of 25 β₂-agonists and 21 β-blockers in urine samples. Urine samples were subjected to enzymatic hydrolysis by β-glucoronidase/arylsulphatase, and then extracted with perchloric acid. Sample clean-up was performed using β-receptor MIP SPE. A Supelco Ascentis® express Rp-Amide column was used to separate the analytes, and MS³ detection used an electrospray ionisation source in positive-ion mode. Recovery studies were carried out using blank urine samples fortified with the 46 analytes at the levels of 0.5, 1.0 and 2.0 μg l⁻¹. Recoveries were obtained ranging from 60.1% to 109.9% with relative standard deviations (RSDs, n = 7) from 0.5% to 19.4%. The limits of detection (LODs) and limits of quantitation (LOQs) of the 46 analytes in urine were 0.02-0.18 and 0.05-0.60 μg l⁻¹, respectively. As a result of the selective clean-up by MIP SPE and MS³ detection of the target drugs, the sensitivity and accuracy of the present method was high enough for monitoring β₂-agonist and β-blocker residues in urine samples. Satisfactory results were obtained in the process of the determination of positive urine samples.

Analytical determination of bisphenol A (BPA) and bisphenol analogues in paper products by GC-MS/MS.

PubMed

Jurek, A; Leitner, E

2017-07-01

Bisphenol A (BPA; 4-[2-(4-hydroxyphenyl)propan-2-yl]phenol), a suspected endocrine disruptor with a weak estrogenic activity, is used in a variety of consumer products, including food-contact materials made of paper and cardboard products. Due to restrictions on the use of BPA because of its potential health risks, BPA is gradually being replaced by other bisphenols because no limitations exist for these substances. This study presents a method for the simultaneous analysis of BPA, bisphenol AF (BPAF), bisphenol B (BPB), bisphenol E (BPE), bisphenol F (BPF) and bisphenol S (BPS) in paper and board products using gas chromatography-tandem mass spectrometry (GC-MS/MS). Paper samples were extracted by liquid extraction, as well as by Folch extraction, derivatised with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and the results compared. The developed method showed good linearity (R 2  > 0.9965) and precision, yielding relative standard deviations (RSDs) of less than 16.6% for reproducibility and 19.8% for repeatability. The limits of detection and limits of quantification for the different bisphenols ranged from 0.23 to 2.70 µg kg - 1 paper and from 0.78 to 9.10 µg kg - 1 paper, respectively. Analysis of different paper products (recycled, virgin fibre) showed that all the analysed bisphenols were present in the samples, except for BPAF and BPB. A calculation of the 'worst-case' scenario assuming a maximum potential migration of 100% of the analytes into food showed that the analysed products can be assumed to be safe regarding the migration of bisphenols.

Development of a selective and pH-independent method for the analysis of ultra trace amounts of nitrite in environmental water samples after dispersive magnetic solid phase extraction by spectrofluorimetry.

PubMed

Daneshvar Tarigh, Ghazale; Shemirani, Farzaneh

2014-10-01

This paper describes an innovative and rapidly dispersive magnetic solid phase extraction spectrofluorimetry (DMSPE-FL) method for the analysis of trace amounts of nitrite in some environmental water samples. The method includes derivatization of aqueous nitrite with 2, 3-diaminonaphthalene (DAN), analysis of highly fluorescent 2, 3-naphthotriazole (NAT) derivative using spectrofluorimetry after DSPME. The novelty of our method is based on forming NAT that was independent with the pH-responsive and was adsorbed on MMWCNT by hydrophobic attractions in both acidic and basic media. The extraction efficiency of the sorbent was investigated by extraction of nitrite. The optimum extraction conditions for NO2(-) were obtained as of extraction time, 1.5 min; 10mg sorbent from 160 mL of the sample solution, and elution with 1 mL of acetone/KOH. Under the optimal conditions, the calibration curves were obtained in the range of 0.1-80 µg L(-1) (R(2)=0.999) and LOD (S/N=3) was obtained in 34 ng L(-1). Relative standard deviations (RSD) were 0.6 % (five replicates at 5 μg L(-1)). In addition, the feasibility of the method was demonstrated with extraction and determination of nitrite from some real samples containing tap, mineral, sea, rain, snow and ground waters, with the recovery in standard addition to real matrix of 94-102 % and RSDs of 1.8-10.6%. Copyright © 2014 Elsevier B.V. All rights reserved.

Optimized ultrasound-assisted emulsification microextraction for simultaneous trace multielement determination of heavy metals in real water samples by ICP-OES.

PubMed

Sereshti, Hassan; Heravi, Yeganeh Entezari; Samadi, Soheila

2012-08-15

Ultrasonic-assisted emulsification microextraction (USAEME) combined with inductively coupled plasma-optical emission spectrometry (ICP-OES) was used for preconcentration and determination of aluminum, bismuth, cadmium, cobalt, copper, iron, gallium, indium, nickel, lead, thallium and zinc in real water samples. Ammonium pyrrolidine dithiocarbamate (APDC) and carbon tetrachloride (CCl(4)) were used as the chelating agent and extraction solvent, respectively. The effective parameters (factors) of the extraction process such as volume of extraction solvent, pH, sonication time, and concentration of chelating agent were optimized by a small central composite design (CCD). The optimum conditions were found to be 98 μL for extraction solvent, 1476 mg L(-1) for chelating agent, 3.8 for pH and 9 min for sonication time. Under the optimal conditions, the limits of detection (LODs) for Al, Bi, Cd, Co, Cu, Fe, Ga, In, Ni, Pb, Tl and Zn were 0.13, 0.48, 0.19, 0.28, 0.29, 0.27, 0.27, 0.38, 0.44, 0.47, 0.52 and 0.17 μg L(-1), respectively. The linear dynamic range (LDR) was 1-1000 μ gL(-1) with determination coefficients of 0.991-0.998. Relative standard deviations (RSDs, C=200 μg L(-1), n=6) were between 1.87%-5.65%. The proposed method was successfully applied to the extraction and determination of heavy metals in real water samples and the satisfactory relative recoveries (90.3%-105.5%) were obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

Preparation of magnetic ODS-PAN thin-films for microextraction of quetiapine and clozapine in plasma and urine samples followed by HPLC-UV detection.

PubMed

Li, Dan; Zou, Juan; Cai, Pei-Shan; Xiong, Chao-Mei; Ruan, Jin-Lan

2016-06-05

In this study, conventional thin-film microextraction (TFME) was endowed with magnetic by introducing superparamagnetic SiO2@Fe3O4 nanoparticles in thin-films. Novel magnetic octadecylsilane (ODS)-polyacrylonitrile (PAN) thin-films were prepared by spraying, and used for the microextraction of quetiapine and clozapine in plasma and urine samples, followed by the detection of HPLC-UV. The influencing factors on the extraction efficiency of magnetic ODS-PAN TFME, including pH, extraction time, desorption solvent, desorption time, and ion strength were investigated systematically. Under the optimal conditions, both analytes showed good linearity over ranges of 0.070-9.000μgmL(-1) and 0.012-9.000μgmL(-1) in plasma and urine samples, respectively, with correlation coefficients (R(2)) above 0.9990. Limits of detection (LODs) for quetiapine in plasma and urine samples were 0.013 and 0.003μgmL(-1), respectively. LODs for clozapine in plasma and urine samples were 0.015 and 0.003μgmL(-1), respectively. The relative standard deviations (RSDs) for quetiapine and clozapine were less than 9.23%. After the validation, the protocol was successfully applied for the determination of quetiapine and clozapine in patients' plasma and urine samples with satisfactory recoveries between 99-110%. The proposed magnetic ODS-PAN TFME was very simple, fast and easy to handle. It showed high potential as a powerful pretreatment technology for routine therapeutic drug monitoring (TDM) in plasma and urine samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of three pesticide adjuvant residues in plant-derived agro-products using liquid chromatography-tandem mass spectrometry.

PubMed

Li, Hui; Jiang, Zejun; Cao, Xiaolin; Su, Hang; Shao, Hua; Jin, Fen; Abd El-Aty, A M; Wang, Jing

2017-12-15

Herein, an accurate and reliable isotope-labelled internal standard method was developed and validated for simultaneous determination of three polar pesticide adjuvants, namely 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone in plant-derived agro-products. Matrices, including apple, cabbage, tomato, cucumber, rice, and wheat were extracted with a modified quick, easy, cheap, effective, rugged, and safe "QuEChERS" method and purified with a new clean-up sorbent (Z-Sep). A hydrophilic interaction liquid chromatography column (HILIC), exhibiting a lipophilic-hydrophilic character, was used to separate the three analytes over 10min using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Matrix effects in various matrices were evaluated and an isotope-labelled internal standard method was employed to compensate for ion enhancement/suppression effects. At three fortification levels (2.0, 5.0, and 20.0μg/kg), the mean recoveries ranged from 78.5 to 112.1% with relative standard deviations (RSDs)<11.0% for all tested analytes. The limits of detection (LODs) and quantification (LOQs) were 0.04-0.45 and 0.12-1.58μg/kg in various matrices, respectively. The developed experimental protocol was successfully applied to monitor different samples purchased from local markets in Beijing, China. In conclusion, the developed method exhibited both high sensitivity and satisfactory accuracy and is suitable for the simultaneous determination of the three tested pesticide adjuvant residues in agro-products of plant origin. Copyright © 2017 Elsevier B.V. All rights reserved.

Hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction for measurement of ibuprofen and naproxen in hair and waste water samples.

PubMed

Rezaeifar, Zohreh; Es'haghi, Zarrin; Rounaghi, Gholam Hossein; Chamsaz, Mahmoud

2016-09-01

A new design of hyperbranched polyglycerol/graphene oxide nanocomposite reinforced hollow fiber solid/liquid phase microextraction (HBP/GO -HF-SLPME) coupled with high performance liquid chromatography used for extraction and determination of ibuprofen and naproxen in hair and waste water samples. The graphene oxide first synthesized from graphite powders by using modified Hummers approach. The surface of graphene oxide was modified using hyperbranched polyglycerol, through direct polycondensation with thionyl chloride. The ready nanocomposite later wetted by a few microliter of an organic solvent (1-octanol), and then applied to extract the target analytes in direct immersion sampling mode.After the extraction process, the analytes were desorbed with methanol, and then detected via high performance liquid chromatography (HPLC). The experimental setup is very simple and highly affordable. The main factors influencing extraction such as; feed pH, extraction time, aqueous feed volume, agitation speed, the amount of functionalized graphene oxide and the desorption conditions have been examined in detail. Under the optimized experimental conditions, linearity was observed in the range of 5-30,000ngmL(-1) for ibuprofen and 2-10,000ngmL(-1) for naproxen with correlation coefficients of 0.9968 and 0.9925, respectively. The limits of detection were 2.95ngmL(-1) for ibuprofen and 1.51ngmL(-1) for naproxen. The relative standard deviations (RSDs) were found to be less than 5% (n=5). Copyright © 2016 Elsevier B.V. All rights reserved.

Analyses of sulfonamide antibiotics in meat samples by on-line concentration capillary electrochromatography-mass spectrometry.

PubMed

Cheng, Yi-Jie; Huang, Sing-Hao; Singco, Brenda; Huang, Hsi-Ya

2011-10-21

In this work, a series of poly(divinylbenzene-alkyl methacrylate) monolithic stationary phases, which were prepared by single step in situ polymerization of divinylbenzene and various alkyl methacrylates (butyl-, octyl-, lauryl- or stearyl methacrylate), were developed as separation columns of nine common sulfonamide antibiotics for capillary electrochromatography (CEC) coupled to mass spectrometry (MS). Results indicated that the sulfonamide's retention became weak with increased carbon chain length of alkyl methacrylate monomer (for example, t(R)=68 min and 21 min for butyl- and lauryl methacrylate, respectively). Among them, the poly(divinylbenzene-octyl methacrylate) (poly(DVB-OMA)) monolith was regarded as the optimal separation column as this provided better resolution within the shortest retention time. Moreover, the cross-sectional roughness of the monolithic column-end, that was used to couple to the ESI interface, strongly influenced the electrospray stability in the CEC-MS. Before the column was connected to the ESI-MS, a simple polishing was done to reduce the roughness of the column end that resulted to a great improvement in the signal stability. The relative standard deviations (RSDs) of the peak areas for the unpolished and polished ends of the poly(DVB-OMA) columns (n=5) were in the range of 46.1-60.2% and 8.9-16.4%, respectively. Furthermore, optimization of the mobile phase composition and the gradient elution strategy successfully determined the sulfonamide antibiotics in meat samples with as low as 10 μg/L level. Copyright © 2011 Elsevier B.V. All rights reserved.

Octadecyltrimethoxysilane functionalized ZnO nanorods as a novel coating for solid-phase microextraction with strong hydrophobic surface.

PubMed

Zeng, Jingbin; Liu, Haihong; Chen, Jinmei; Huang, Jianli; Yu, Jianfeng; Wang, Yiru; Chen, Xi

2012-09-21

In this paper, we have, for the first time, proposed an approach by combining self-assembled monolayers (SAMs) and nanomaterials (NMs) for the preparation of novel solid-phase microextraction (SPME) coatings. The self-assembly of octadecyltrimethoxysilane (OTMS) on the surface of ZnO nanorods (ZNRs) was selected as a model system to demonstrate the feasibility of this approach. The functionalization of OTMS on the surface of ZNRs was characterized and confirmed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The OTMS-ZNRs coated fiber exhibited stronger hydrophobicity after functionalization, and its extraction efficiency for non-polar benzene homologues was increased by a factor of 1.5-3.6 when compared to a ZNRs fiber with almost identical thickness and façade. In contrast, the extraction efficiency of the OTMS-ZNRs coated fiber for polar aldehydes was 1.6-4.0-fold lower than that of the ZNRs coated fiber, further indicating its enhanced surface hydrophobicity. The OTMS-ZNRs coated fiber revealed a much higher capacity upon increasing the OTMS layer thickness to 5 μm, leading to a factor of 12.0-13.4 and 1.8-2.5 increase in extraction efficiency for the benzene homologues relative to a ZNRs coated fiber and a commercial PDMS fiber, respectively. The developed HS-SPME-GC method using the OTMS-ZNRs coated fiber was successfully applied to the determination of the benzene homologues in limnetic water samples with recovery ranging from 83 to 113% and relative standard deviations (RSDs) of less than 8%.

Application of a simple column-switching ion chromatography technique for removal of matrix interferences and sensitive fluorescence determination of acidic compounds (pharmaceutical drugs) in complex samples.

PubMed

Muhammad, Nadeem; Subhani, Qamar; Wang, Fenglian; Guo, Dandan; Zhao, Qiming; Wu, Shuchao; Zhu, Yan

2017-09-15

This work illustrates the introduction of a simple, rugged and flexible column-switching ion chromatography (IC) technique for an automated on-line QuEChERS extracted samples extracts washing followed by sensitive fluorescence (FLD) determination of five acidic pharmaceutical drugs namely; clofibric acid (CLO), ibuprofen (IBU), aspirin (ASP), naproxen (NAP) and flurobrofen (FLU) in three complex samples (spinach, apple and hospital sewage sludge). An old anion exchange column IonPac ® AS11-HC was utilized as a pre-treatment column for on-line washing of inorganic and organic interferences followed by isocratic separation of five acidic drugs with another anion exchange IonPac ® AS12A analytical column by exploiting the column-switching technique. This novel method exhibited good linearity with correlation coefficients (r 2 ) for all drugs were in the range 0.976-0.996. The limit of detection and quantification of all five acidic drugs were in the range 0.024μg/kg to 8.70μg/kg and 0.082μg/kg to 0.029mg/kg, respectively, and better recoveries in the range 81.17-112.5% with percentage relative standard deviations (RSDs) less than 17.8% were obtained. This on-line sample pre-treatment method showed minimum matrix effect in the range of 0.87-1.25 except for aspirin. This simple rugged and flexible column-switching system required only 28min for maximum elimination of matrices and interferences in three complex samples extracts, isocratic separation of five acidic drugs and for the continuous regeneration of pre-treatment column prior to every subsequent analysis. Finally, this simple automated IC system was appeared so rugged and flexible, which can eliminate and wash out most of interference, impurities and matrices in complex samples, simply by adjusting the NaOH and acetonitrile concentration in washing mobile phase with maximum recoveries of acidic analytes of interest. Copyright © 2017. Published by Elsevier B.V.

Analysis of chemical warfare agents in organic liquid samples with magnetic dispersive solid phase extraction and gas chromatography mass spectrometry for verification of the chemical weapons convention.

PubMed

Singh, Varoon; Purohit, Ajay Kumar; Chinthakindi, Sridhar; Goud, Raghavender D; Tak, Vijay; Pardasani, Deepak; Shrivastava, Anchal Roy; Dubey, Devendra Kumar

2016-05-27

A simple, sensitive and low temperature sample preparation method is developed for detection and identification of Chemical Warfare Agents (CWAs) and scheduled esters in organic liquid using magnetic dispersive solid phase extraction (MDSPE) followed by gas chromatography-mass spectrometry analysis. The method utilizes Iron oxide@Poly(methacrylic acid-co-ethylene glycol dimethacrylate) resin (Fe2O3@Poly(MAA-co-EGDMA)) as sorbent. Variants of these sorbents were prepared by precipitation polymerization of methacrylic acid-co-ethylene glycol dimethacrylate (MAA-co-EGDMA) onto Fe2O3 nanoparticles. Fe2O3@poly(MAA-co-EGDMA) with 20% MAA showed highest recovery of analytes. Extractions were performed with magnetic microspheres by MDSPE. Parameters affecting the extraction efficiency were studied and optimized. Under the optimized conditions, method showed linearity in the range of 0.1-3.0μgmL(-1) (r(2)=0.9966-0.9987). The repeatability and reproducibility (relative standard deviations (RSDs) %) were in the range of 4.5-7.6% and 3.4-6.2% respectively for organophosphorous esters in dodecane. Limits of detection (S/N=3/1) and limit of quantification (S/N=10/1) were found to be in the range of 0.05-0.1μgmL(-1) and 0.1-0.12μgmL(-1) respectively in SIM mode for selected analytes. The method was successfully validated and applied to the extraction and identification of targeted analytes from three different organic liquids i.e. n-hexane, dodecane and silicon oil. Recoveries ranged from 58.7 to 97.3% and 53.8 to 95.5% at 3μgmL(-1) and 1μgmL(-1) spiking concentrations. Detection of diethyl methylphosphonate (DEMP) and O-Ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX) in samples provided by the Organization for Prohibition of Chemical Weapons Proficiency Test (OPCW-PT) proved the utility of the developed method for the off-site analysis of CWC relevant chemicals. Copyright © 2016 Elsevier B.V. All rights reserved.

Direct determination of the estrogenic compounds 8-prenylnaringenin, zearalenone, alpha- and beta-zearalenol in beer by liquid chromatography-mass spectrometry.

PubMed

Maragou, Niki C; Rosenberg, Erwin; Thomaidis, Nikolaos S; Koupparis, Michael A

2008-08-15

A novel LC-ESI-MS method for the simultaneous determination of four of the most significant estrogenic compounds naturally occurring in beer, 8-prenylnaringenin (8-PN), zearalenone (ZON), alpha-zearalenol (alpha-ZOL) and beta-zearalenol (beta-ZOL) which requires minimal sample preparation was developed using a chemometric approach. Experimental design was applied to assess the effects of the LC-ESI-MS parameters (mobile phase flow rate, drying gas flow, nebuliser pressure and capillary potential) on the obtained signal and to optimize the values in order to provide maximum sensitivity and detectability. The proposed method is simple, consisting only of degassing the beer and diluting with water (1:1, v/v) before injection. Comparison between the two internal standards used, zearalanone (ZAN) and 4,2'-dihydroxychalcone (4,2'-DHC), showed that ZAN performs better as internal standard not only for the mycotoxins but for 8-PN as well, giving lower % RSDs. Under inter-day conditions mean recoveries were 107% for ZON, 87.8% for alpha-ZOL, 72.8% for beta-ZOL, and 77.5% for 8-PN. The corresponding % RSDs ranged between 5.0 and 8.0. The method limits of detection were 1.3, 1.4, 1.0 and 0.8 ng mL(-1) for ZON, alpha-ZOL, beta-ZOL and 8-PN, respectively. The method was applied to 15 beer samples obtained from local supermarkets and the concentration of the phytoestrogen 8-PN in beer ranged between <0.8 and 38.6 ng mL(-1), while neither ZON nor its metabolites, alpha-ZOL and beta-ZOL, were detected.

[Determination of optical purity of alpha-phenylethylamine by high performance liquid chromatography with pre-column derivatization].

PubMed

Wang, Jinzhao; Zeng, Su; Wang, Danhua; Hu, Gongyun

2009-05-01

A simple pre-column derivatization-high performance liquid chromatographic (HPLC) method was established for the determination of optical purity of alpha-phenylethylamine. The enantiomers of alpha-phenylethylamine were derivatized with 2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl isothiocyanate (GITC). The resulted diastereoisomers were separated on an Agilent Zorbax C18 column (250 mm x 4.6 mm, 5 microm) with a mobile phase of methanol-phosphate buffer (1.36 g/L aqueous solution of potassium dihydrogen phosphate, adjusted to pH 3.0 with concentrated phosphoric acid) (58:42, v/v). The flow rate was set at 1.0 mL/min and the detection wavelength was set at 241 nm. The method was linear from 0.15 - 15.0 mg/L for both enantiomers. The limit of detection and the limit of quantification were 0.05 mg/L and 0.15 mg/L, respectively. The relative standard deviations (RSDs) of inter- and intra-day determination were below 0.5%. The method is easy to handle, accurate, and suitable for the quality control of the optical purity of alpha-phenylethylamine.

[Determination of canthaxanthin and astaxanthin in egg yolks by reversed phase high performance liquid chromatography with diode array detection].

PubMed

He, Kang-Hao; Zou, Xiao-Li; Liu, Xiang; Zeng, Hong-Yan

2012-01-01

A method using reversed phase high performance liquid chromatography (RP-HPLC) coupled with diode array detector (DAD) was developed for the simultaneous determination of canthaxanthin and astaxanthin in egg yolks. Samples were extracted with acetonitrile in ultrasonic bath for 20 minutes and then purified by freezing-lipid filtration and solid phase extraction (SPE). After being vaporized to dryness by nitrogen blowing and made up to volume with methanol, the extract solution was chromatographically separated in C18 column with a unitary mobile phase consisting of acetonitrile. The proposed method was validated in terms of linearity, precision, accuracy, and limit of detection (LOD). Regression analysis revealed a good linearity between peak area of each analyte and its concentration (r > or = 0.998). The intra- and inter-day relative standard deviations (RSDs) were less than 3.6% and 5.2%, respectively. LODs of canthaxanthin and astaxanthin were 0.035 and 0.027 microg/mL (S/N = 3). The average recoveries of canthaxanthin and astaxanthin were 91.5% and 88.7%. The proposed method is simple, fast and easy to apply.

[Determination of lambda-cyhalothrin residue tea and soil using gas chromatography].

PubMed

Chen, Linglong; Chen, Jiuxing; Ma, Ming; Chen, Lihua; Yang, Hui; Zhang, Guiqun

2010-08-01

A gas chromatographic (GC) method was established for the determination of lambda-cyhalothrin residue in tea and soil. Tea and soil samples were extracted with hexane, separated by capillary column and determined by gas chromatography-electron capture detector (GC-ECD). The average recoveries of lambda-cyhalothrin in tea and soil were 89.0% - 94.1% and 89.8% - 94.7%, respectively at the spiking levels of 0.02 to 2.00 mg/kg. The corresponding relative standard deviations (RSDs, n = 5) were 3.0% -4.9% and 2.5% -4.2%, respectively. The limit of detection (S/N = 3) was 0.002 mg/kg for lambda-cyhalothrin. The degradations of 2.5% lambda-cyhalothrin microemulsion in tea and soil in Changsha, Hunan were investigated and the degradation equations were Y = 3.199 6e(-0.339 4x) and Y = 0.122 4e(-0.103 6x) with the correlation coefficients of 0.995 6 and 0.924 7, respectively. The half-lives of lambda-cyhalothrin in tea and soil were 2.04 days and 6.69 days, respectively.

Repeatability Assessment by ISO 11843-7 in Quantitative HPLC for Herbal Medicines.

PubMed

Chen, Liangmian; Kotani, Akira; Hakamata, Hideki; Tsutsumi, Risa; Hayashi, Yuzuru; Wang, Zhimin; Kusu, Fumiyo

2015-01-01

We have proposed an assessment methods to estimate the measurement relative standard deviation (RSD) of chromatographic peaks in quantitative HPLC for herbal medicines by the methodology of ISO 11843 Part 7 (ISO 11843-7:2012), which provides detection limits stochastically. In quantitative HPLC with UV detection (HPLC-UV) of Scutellaria Radix for the determination of baicalin, the measurement RSD of baicalin by ISO 11843-7:2012 stochastically was within a 95% confidence interval of the statistically obtained RSD by repetitive measurements (n = 6). Thus, our findings show that it is applicable for estimating of the repeatability of HPLC-UV for determining baicalin without repeated measurements. In addition, the allowable limit of the "System repeatability" in "Liquid Chromatography" regulated in a pharmacopoeia can be obtained by the present assessment method. Moreover, the present assessment method was also successfully applied to estimate the measurement RSDs of quantitative three-channel liquid chromatography with electrochemical detection (LC-3ECD) of Chrysanthemi Flos for determining caffeoylquinic acids and flavonoids. By the present repeatability assessment method, reliable measurement RSD was obtained stochastically, and the experimental time was remarkably reduced.

Determination of linuron and related compounds in soil by microwave-assisted solvent extraction and reversed-phase liquid chromatography with UV detection.

PubMed

Molins, C; Hogendoorn, E A; Dijkman, E; Heusinkveld, H A; Baumann, R A

2000-02-11

The combination of microwave-assisted solvent extraction (MASE) and reversed-phase liquid chromatography (RPLC) with UV detection has been investigated for the efficient determination of phenylurea herbicides in soils involving the single-residue method (SRM) approach (linuron) and the multi-residue method (MRM) approach (monuron, monolinuron, isoproturon, metobromuron, diuron and linuron). Critical parameters of MASE, viz, extraction temperature, water content and extraction solvent were varied in order to optimise recoveries of the analytes while simultaneously minimising co-extraction of soil interferences. The optimised extraction procedure was applied to different types of soil with an organic carbon content of 0.4-16.7%. Besides freshly spiked soil samples, method validation included the analysis of samples with aged residues. A comparative study between the applicability of RPLC-UV without and with the use of column switching for the processing of uncleaned extracts, was carried out. For some of the tested analyte/matrix combinations the one-column approach (LC mode) is feasible. In comparison to LC, coupled-column LC (LC-LC mode) provides high selectivity in single-residue analysis (linuron) and, although less pronounced in multi-residue analysis (all six phenylurea herbicides), the clean-up performance of LC-LC improves both time of analysis and sample throughput. In the MRM approach the developed procedure involving MASE and LC-LC-UV provided acceptable recoveries (range, 80-120%) and RSDs (<12%) at levels of 10 microg/kg (n=9) and 50 microg/kg (n=7), respectively, for most analyte/matrix combinations. Recoveries from aged residue samples spiked at a level of 100 microg/kg (n=7) ranged, depending of the analyte/soil type combination, from 41-113% with RSDs ranging from 1-35%. In the SRM approach the developed LC-LC procedure was applied for the determination of linuron in 28 sandy soil samples collected in a field study. Linuron could be determined in soil with a limit of quantitation of 10 microg/kg.

Determination of caramel colorants' by-products in liquid foods by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

PubMed

Goscinny, Séverine; Hanot, Vincent; Trabelsi, Hasna; Van Loco, Joris

2014-01-01

2-Methylimidazole, 4-methylimidazole (2-MI and 4-MI), 2-acetyl-4-(1,2,3,4-tetrahydroxybutyl) imidazole (THI) and 5-hydroxymethylfurfural (5-HMF) are neo-formed compounds generated during the manufacture of caramel colours and are transferred to the processed food. These contaminants are known to have a toxicological profile that may pose health risks. Hence, to characterise THI, 2- and 4-MI and 5-HMF levels in liquid foods, an ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and sample preparation was divided into two analytical strategies depending on the concentration range expected in the type of foods targeted. For the determination of the imidazole substitutes (THI, 2- and 4-MI), a sample enrichment and clean-up step by strong cation solid-phase extraction was developed. This method is capable of quantifying over a range of 5 ng ml⁻¹ (LOQ) to 500 ng ml⁻¹ with recoveries of 75.4-112.4% and RSDs of 1.5-15%. For determination of 5-HMF, a standard addition method was applied covering the linear range of 0.25-30 µg ml⁻¹ with RSDs from 2.8% (for intraday precision) to 9.2% (for intermediate precision). The validated analytical methods were applied to 28 liquid food samples purchased from local markets. THI was found only in the beer samples at levels up to 141.2 ng ml⁻¹. For 2-MI, non-quantifiable traces were observed for all samples, while 4-MI was observed in all samples with large concentration variations (from < LOQ to 563.9 ng ml⁻¹). 5-HMF was found at expected concentrations, except for a sherry vinegar sample (113 µg ml⁻¹), which required a high level of dilution before following the standard addition protocol.

Validation of an automated solid-phase extraction method for the analysis of 23 opioids, cocaine, and metabolites in urine with ultra-performance liquid chromatography-tandem mass spectrometry.

PubMed

Ramírez Fernández, María del Mar; Van Durme, Filip; Wille, Sarah M R; di Fazio, Vincent; Kummer, Natalie; Samyn, Nele

2014-06-01

The aim of this work was to automate a sample preparation procedure extracting morphine, hydromorphone, oxymorphone, norcodeine, codeine, dihydrocodeine, oxycodone, 6-monoacetyl-morphine, hydrocodone, ethylmorphine, benzoylecgonine, cocaine, cocaethylene, tramadol, meperidine, pentazocine, fentanyl, norfentanyl, buprenorphine, norbuprenorphine, propoxyphene, methadone and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine from urine samples. Samples were extracted by solid-phase extraction (SPE) with cation exchange cartridges using a TECAN Freedom Evo 100 base robotic system, including a hydrolysis step previous extraction when required. Block modules were carefully selected in order to use the same consumable material as in manual procedures to reduce cost and/or manual sample transfers. Moreover, the present configuration included pressure monitoring pipetting increasing pipetting accuracy and detecting sampling errors. The compounds were then separated in a chromatographic run of 9 min using a BEH Phenyl analytical column on a ultra-performance liquid chromatography-tandem mass spectrometry system. Optimization of the SPE was performed with different wash conditions and elution solvents. Intra- and inter-day relative standard deviations (RSDs) were within ±15% and bias was within ±15% for most of the compounds. Recovery was >69% (RSD < 11%) and matrix effects ranged from 1 to 26% when compensated with the internal standard. The limits of quantification ranged from 3 to 25 ng/mL depending on the compound. No cross-contamination in the automated SPE system was observed. The extracted samples were stable for 72 h in the autosampler (4°C). This method was applied to authentic samples (from forensic and toxicology cases) and to proficiency testing schemes containing cocaine, heroin, buprenorphine and methadone, offering fast and reliable results. Automation resulted in improved precision and accuracy, and a minimum operator intervention, leading to safer sample handling and less time-consuming procedures.

Black phosphorus-assisted laser desorption ionization mass spectrometry for the determination of low-molecular-weight compounds in biofluids.

PubMed

He, Xiao-Mei; Ding, Jun; Yu, Lei; Hussain, Dilshad; Feng, Yu-Qi

2016-09-01

Quantitative analysis of small molecules by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been a challenging task due to matrix-derived interferences in low m/z region and poor reproducibility of MS signal response. In this study, we developed an approach by applying black phosphorus (BP) as a matrix-assisted laser desorption ionization (MALDI) matrix for the quantitative analysis of small molecules for the first time. Black phosphorus-assisted laser desorption/ionization mass spectrometry (BP/ALDI-MS) showed clear background and exhibited superior detection sensitivity toward quaternary ammonium compounds compared to carbon-based materials. By combining stable isotope labeling (SIL) strategy with BP/ALDI-MS (SIL-BP/ALDI-MS), a variety of analytes labeled with quaternary ammonium group were sensitively detected. Moreover, the isotope-labeled forms of analytes also served as internal standards, which broadened the analyte coverage of BP/ALDI-MS and improved the reproducibility of MS signals. Based on these advantages, a reliable method for quantitative analysis of aldehydes from complex biological samples (saliva, urine, and serum) was successfully established. Good linearities were obtained for five aldehydes in the range of 0.1-20.0 μM with correlation coefficients (R (2)) larger than 0.9928. The LODs were found to be 20 to 100 nM. Reproducibility of the method was obtained with intra-day and inter-day relative standard deviations (RSDs) less than 10.4 %, and the recoveries in saliva samples ranged from 91.4 to 117.1 %. Taken together, the proposed SIL-BP/ALDI-MS strategy has proved to be a reliable tool for quantitative analysis of aldehydes from complex samples. Graphical Abstract An approach for the determination of small molecules was developed by using black phosphorus (BP) as a matrix-assisted laser desorption ionization (MALDI) matrix.

[Determination of six anticoccidials in chicken using QuEChERS combined with ultra high liquid chromatography-high resolution mass spectrometry].

PubMed

Muharem, Muhteber; Yan, Hua; Xu, Shan; Feng, Nan; Hao, Jie; Zhu, Chenqi; Guo, Shuang; Zhang, Zhaohui; Han, Nanyin

2015-11-01

An ultra high liquid chromatography-Q Exactive orbitrap mass spectrometry multi-residue method has been developed for the determination of six anticoccidials residues (dinitlmide, nicarbazin, diclazuril, toltrazuril, monensin and salinomycin) in chicken tissue. Sample preparation was based on QuEChERS method, using 1% (v/v) trichloroacetic acid/acetonitrile aqueous solution (3:7, v/v) as the extraction solvent and salting-out with sodium chloride followed by clean-up with 50 mg/mL primary secondary amine (PSA) +50 mg/mL neutral alumina (Alumina-N) dispersive solid phase extraction (DSPE). The separation of the compounds in liquid chromatography was carried out using a Waters Acquity UPLC BEH C8 column (100 mm x 2.1 mm, 1.7 μm) with mobile phases consisting of methanol-5 mmol/L ammonium acetate aqueous solution in gradient elution. The Q Exactive orbitrap mass spectrometric detection was carried out with positive and negative electrospray ionization simultaneously. The results showed the linear ranges of the six target compounds were as follows: dinitolmide, 1.0-30.0 μg/L; nicarbazin, 0.2-6.0 μg/L; diclazuril and toltrazuril, 2.0-60.0 [μg/L; monensin and salinomycin, 4.0-120.0 μg/L. The external standard method was used for quantification. The spiked recoveries at three levels for the six anticoccidials ranged from 67.7% to 126.8%. The relative standard deviations (RSDs) were ≤ 10.4%. The limits of quantification (LOQs) were as follows: dinitolmide, 2.50 μg/kg; nicarbazin, 0.50 μg/kg; diclazuril and toltrazuril, 5.00 μg/kg; monensin and salinomycin, 20.00 μg/kg. The developed method is easy of operation and of high sensitivity. It can meet the requirements of daily inspection.

Determination of Montelukast in Plasma Using β - Cyclodextrins Coated on CoFe2O4 Magnetic Nanoparticles in Luminol-H2O2 Chemiluminescence System Optimized by Doehlert Design.

PubMed

Samadi-Maybodi, Abdolraouf; Bakhtiar, Alireza; Fatemi, Mohammad Hossein

2016-05-01

A novel chemiluminescence method using β - cyclodextrins coated on CoFe2O4 magnetic nanoparticles is proposed for the chemiluminometric determination of montelukast in plasma. The effect of coated β - cyclodexterinon CoFe2O4 magnetic nanoparticles in the chemiluminescence of luminol-H2O2 system was investigated. It was found that β - cyclodexterin coated on CoFe2O4 magnetic nanoparticles could greatly enhance the chemiluminescence of the luminol-H2O2 system. Doehlert design was applied in order to optimize the number of experiments to be carried out to ascertain the possible interactions between the parameters and their effects on the chemiluminescence emission intensity. This design was selected because the levels of each variable may vary in a very efficient way with few experiments. Doehlert design and response surface methodology have been employed for optimization pH and concentrations of the components. Results showed under the optimized experimental conditions, the relative CL intensity (ΔI) is increased linearly in the concentration range of 0.003-0.586 μgml(-1) of montelukast with limit of detection (LOD) 1.09 × 10(-4) μgml(-1) at S/N ratio of 3, limit of quantitative (LOQ) 3.59 × 10(-4) μgml(-1) and the relative standard deviation 2.63 %. The method has been successfully applied to the determination of montelukast in plasma of human body. Results specified that relative chemiluminescence intensity (ΔI) has good proportional with the montelukast concentration with R(2) = 0.99979. The test of the recovery efficiency for known amounts of montelukast was also performed, the recoveries range obtained from 98.2 to 103.3 %, with RSDs of <4 % indicated that the proposed method was reliable.

Determination of novel brominated flame retardants and polybrominated diphenyl ethers in serum using gas chromatography-mass spectrometry with two simplified sample preparation procedures.

PubMed

Gao, Le; Li, Jian; Wu, Yandan; Yu, Miaohao; Chen, Tian; Shi, Zhixiong; Zhou, Xianqing; Sun, Zhiwei

2016-11-01

Two simple and efficient pretreatment procedures have been developed for the simultaneous extraction and cleanup of six novel brominated flame retardants (NBFRs) and eight common polybrominated diphenyl ethers (PBDEs) in human serum. The first sample pretreatment procedure was a quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based approach. An acetone/hexane mixture was employed to isolate the lipid and analytes from the serum with a combination of MgSO 4 and NaCl, followed by a dispersive solid-phase extraction (d-SPE) step using C18 particles as a sorbent. The second sample pretreatment procedure was based on solid-phase extraction. The sample extraction and cleanup were conducted directly on an Oasis HLB SPE column using 5 % aqueous isopropanol, concentrated sulfuric acid, and 10 % aqueous methanol, followed by elution with dichloromethane. The NBFRs and PBDEs were then detected using gas chromatography-negative chemical ionization mass spectrometry (GC-NCI MS). The methods were assessed for repeatability, accuracy, selectivity, limits of detection (LODs), and linearity. The results of spike recovery experiments in fetal bovine serum showed that average recoveries ranged from 77.9 % to 128.8 % with relative standard deviations (RSDs) from 0.73 % to 12.37 % for most of the analytes. The LODs for the analytes in fetal bovine serum ranged from 0.3 to 50.8 pg/mL except for decabromodiphenyl ethane. The proposed method was successfully applied to the determination of the 14 brominated flame retardants in human serum. The two pretreatment procedures described here are simple, accurate, and precise, and are suitable for the routine analysis of human serum. Graphical Abstract Workflow of a QuEChERS-based approach (top) and an SPE-based approach (bottom) for the detection of PBDEs and NBFRs in serum.

Ultrasound-assisted leaching-dispersive solid-phase extraction followed by liquid-liquid microextraction for the determination of polybrominated diphenyl ethers in sediment samples by gas chromatography-tandem mass spectrometry.

PubMed

Fontana, Ariel R; Lana, Nerina B; Martinez, Luis D; Altamirano, Jorgelina C

2010-06-30

Ultrasound-assisted leaching-dispersive solid-phase extraction followed by dispersive liquid-liquid microextraction (USAL-DSPE-DLLME) technique has been developed as a new analytical approach for extracting, cleaning up and preconcentrating polybrominated diphenyl ethers (PBDEs) from sediment samples prior gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. In the first place, PBDEs were leached from sediment samples by using acetone. This extract was cleaned-up by DSPE using activated silica gel as sorbent material. After clean-up, PBDEs were preconcentrated by using DLLME technique. Thus, 1 mL acetone extract (disperser solvent) and 60 microL carbon tetrachloride (extraction solvent) were added to 5 mL ultrapure water and a DLLME technique was applied. Several variables that govern the proposed technique were studied and optimized. Under optimum conditions, the method detection limits (MDLs) of PBDEs calculated as three times the signal-to-noise ratio (S/N) were within the range 0.02-0.06 ng g(-1). The relative standard deviations (RSDs) for five replicates were <9.8%. The calibration graphs were linear within the concentration range of 0.07-1000 ng g(-1) for BDE-47, 0.09-1000 ng g(-1) for BDE-100, 0.10-1000 ng g(-1) for BDE-99 and 0.19-1000 ng g(-1) for BDE-153 and the coefficients of estimation were > or =0.9991. Validation of the methodology was carried out by standard addition method at two concentration levels (0.25 and 1 ng g(-1)) and by comparing with a reference Soxhlet technique. Recovery values were > or =80%, which showed a satisfactory robustness of the analytical methodology for determination of low PBDEs concentration in sediment samples. Copyright 2010 Elsevier B.V. All rights reserved.

A useful strategy based on chromatographic data combined with quality-by-design approach for food analysis applications. The case study of furanic derivatives in sugarcane honey.

PubMed

Silva, Pedro; Silva, Catarina L; Perestrelo, Rosa; Nunes, Fernando M; Câmara, José S

2017-10-20

Sugarcane honey (SCH) is one of the Madeira Island products par excellence and it is now popular worldwide. Its sui generis and peculiar sensory properties, explained by a variety of volatile compounds including furanic derivatives (FDs), arise mainly from manufacturing and storage conditions. A simple high-throughput approach based on semi-automatic microextraction by packed sorbent (MEPS) combined with ultra-high performance liquid chromatography (UHPLC) was developed and validated for identification and quantification of target FDs in sugarcane honey. A Quality-by-Design (QbD) approach was used as a powerful strategy to optimize analytical conditions for high throughput analysis of FDs in complex sugar-rich food matrices. The optimum point into MEPS-Method Operable Design: Region (MODR) was obtained with R-CX sorbent, acetonitrile (ACN) as elution solvent, three loading cycles and 500μL of sample volume. The optimum point into UHPLC-MODR was obtained with a CORTECS column operating at a temperature of 50°C, ACN as eluent and a flow rate of 125μLmin -1 . The robustness was demonstrated by Monte Carlo simulation and capability analysis for estimation of residual errors. The concentration-response relationship for all FDs were described by polynomial function models, being confirmed by Fisher variance (F-test). The% recoveries were in a range of 91.9-112.1%. Good method precision was observed, yielding relative standard deviations (RSDs) less than 4.9% for repeatability and 8.8% for intermediate precision. The limits of quantitation for the analytes ranged from 30.6 to 737.7μgkg -1 . The MEPS R-CX /UHPLC CORTECS -PDA method revealed an effective and potential analytical tool for SCH authenticity control based on target analysis of FDs allowing a strict control and differentiation from other similar or adulterated products. Copyright © 2017 Elsevier B.V. All rights reserved.

Simultaneous determination and identity confirmation of thiodicarb and its degradation product methomyl in animal-derived foodstuffs using high-performance liquid chromatography with fluorescence detection and tandem mass spectrometry.

PubMed

Rahman, Md Musfiqur; Abd El-Aty, A M; Kim, Sung-Woo; Lee, Young-Jun; Na, Tae-Woong; Park, Joon-Seong; Shin, Ho-Chul; Shim, Jae-Han

2017-01-01

A high-performance liquid chromatography-fluorescence detection method was developed for the simultaneous determination of thiodicarb and its degradation product methomyl in animal-derived food products, including chicken muscle, beef, pork, table eggs, and milk. Thiodicarb is known to degrade during analysis; therefore, a thorough investigation was carried out, revealing that thiodicarb degrades to methomyl immediately after spiking into a matrix of animal-derived food products. Consequently, thiodicarb was determined as the sum of the parent compound and methomyl. Samples were extracted with acetonitrile and sodium salts, and purified using solid-phase extraction (SPE). The limits of detection (LODs) and quantification (LOQs) were 0.0013 and 0.004mg/kg, respectively, for both analytes in various matrices. Seven-point external calibration curves were obtained, and they showed excellent linearity with determination coefficients (R 2 )≥0.999 for all tested matrices. The method was validated at three fortification levels (LOQ, LOQ×2, and LOQ×10) in triplicate with average recoveries ranging from 84.24 to 112.8% (for methomyl) and relative standard deviations (RSDs)≤6.5% in all matrices. The converted recoveries of thiodicarb in various matrices ranged from 74.80 to 107.80% with RSDs≤4.5%. The identities of both compounds in standard solutions and for recovery were confirmed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The developed method was further validated by accurate reproduction at another laboratory. Finally, the method was applied to market samples collected from different areas (and, in the case of milk, different brands), and none of the samples tested positive for thiodicarb or methomyl. In conclusion, the developed method can be successfully applied for a single-run analysis of thiodicarb and methomyl in livestock products. Copyright © 2016 Elsevier B.V. All rights reserved.

Ternary mixed-mode silica sorbent of solid-phase extraction for determination of basic, neutral and acidic drugs in human serum.

PubMed

Jin, Shupei; Qiao, Yinghua; Xing, Jun

2018-06-01

In this study, a ternary mixed-mode silica sorbent (TMSS) with octamethylene, carboxyl, and amino groups was prepared via Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction and a subsequent reduction of azide to primary amine. While used in solid-phase extraction (SPE), the retention behavior of TMSS towards a total of nine kinds of basic, neutral, and acidic drugs was investigated in detail. The results revealed that hydrophobic, ion-exchange interaction, and electrostatic repulsion between TMSS and the analytes were closely related to the retention behavior of TMSS. Besides, the log K ow value of the analyte was also a factor influencing the retention behavior of analytes on TMSS. The nine analytes could be retained by TMSS simultaneously and then, were eluted into two fractions according to the acid-base property of the analytes for further determinations. The acidic and neutral analytes were in one fraction, and the basic ones in the other fraction. When used to treat the human serum spiked with the nine drugs, TMSS offered higher recoveries than BakerBond CBA and comparable recoveries to Oasis WCX. It should be noted TMSS had better purifying capability for human serum than Oasis WCX. Under the optimized SPE conditions, a method of SPE hyphenated to high-performance liquid chromatography-ultraviolet detection (HPLC-UV) for determination of the basic, neutral, and acidic drugs spiked in human serum was established. For the nine drugs, the linear ranges were all between 5.0 and 1000 μg L -1 with correlation coefficients (R 2 ) above 0.9990, and the limits of detection (LODs) were in the range of 0.8-2.3 μg L -1 . The intra-day and inter-day relative standard deviations (RSDs) were less than 5.3 and 8.8%, respectively. Graphical abstract Treating drugs in human serum by SPE with ternary mixed-mode silica sorbent.

Simultaneous quantification and inhibitory effect on LDL oxidation of the traditional Korean medicine, Leejung-tang

PubMed Central

2014-01-01

Background Leejung-tang (LJT) is a traditional Korean herbal medicine for the treatment of gastrointestinal disorders. In this study, we performed quantification analysis of five marker components, liquiritin (1), ginsenoside Rg1 (2), ginsenoside Rb1 (3), glycyrrhizin (4), and 6-gingerol (5) in LJT using a high performance liquid chromatography-photodiode array (HPLC–PDA). In addition, we investigated the inhibitory effect on low-density lipoprotein (LDL) oxidation by the LJT sample. Methods Compounds 1–5 were separated within 35 min using a Gemini C18 column. The mobile phase used gradient elution with 1.0% (v/v) aqueous acetic acid (A) and 1.0% (v/v) acetic acid in acetonitrile (B). The flow rate was 1.0 mL/min and the detector was a photodiode array (PDA) set at 203 nm, 254 nm, and 280 nm. The inhibitory effect on LDL oxidation conduct an experiment on thiobarbituric acid reactive substance (TBARS) assay, relative electrophoretic mobility (REM) assay, and electrophoresis of ApoB fragmentation of LJT. Results Calibration curves of compounds 1–5 showed good linearity (r2 ≥0.9995) in different concentration ranges. The recoveries of compounds 1–5 were in the range of 98.90–103.39%, with relative standard deviations (RSD) below 3.0%. The RSDs (%) of intra-day and inter-day precision were 0.10–1.08% and 0.29–1.87%, respectively. The inhibitory effect of LJT on Cu2+-induced LDL oxidation was defined by TBARS assay (IC50: 165.7 μg/mL) and REM of oxLDL (decrease of 50% at 127.7 μg/mL). Furthermore LJT reduced the fragmentation of ApoB of oxLDL in a dose-dependent manner. Conclusions The established HPLC-PDA method will be helpful to improve quality control of LJT. In addition, LJT is a potential LDL oxidation inhibitor. PMID:24383717

Determination of 18 veterinary antibiotics in environmental water using high-performance liquid chromatography-q-orbitrap combined with on-line solid-phase extraction.

PubMed

Kim, Chansik; Ryu, Hong-Duck; Chung, Eu Gene; Kim, Yongseok

2018-05-01

The use of antibiotics and their occurrence in the environment have received significant attention in recent years owing to the generation of antibiotic-resistant bacteria. Antibiotic residues in water near livestock farming areas should be monitored to establish effective strategies for reducing the use of veterinary antibiotics. However, environmental water contamination resulting from veterinary antibiotics has not been studied extensively. In this work, we developed an analytical method for the simultaneous determination of multiple classes of veterinary antibiotic residues in environmental water using on-line solid-phase extraction (SPE)-high performance liquid chromatography (HPLC)-high resolution mass spectrometry (HRMS). Eighteen popular antibiotics (eight classes) were selected as target analytes based on veterinary antibiotics sales in South Korea in 2015. The developed method was validated by calibration-curve linearities, precisions, relative recoveries, and method detection limits (MDLs)/limits of quantification (LOQs) of the selected antibiotics, and applied to the analysis of environmental water samples (groundwater, river water, and wastewater-treatment-plant effluent). All calibration curves exhibited r 2  > 0.995 with MDLs ranging from 0.2 to 11.9 ng/L. Relative recoveries were between 50 and 150% with coefficients of variation below 20% for all analytes (spiked at 500 ng/L) in groundwater and river water samples. Relative standard deviations (RSDs) of standard-spiked samples were lower than 7% for all antibiotics. The on-line SPE system eliminates human-based SPE errors and affords excellent method reproducibility. Amoxicillin, ampicillin, clopidol, fenbendazole, flumequine, lincomycin, sulfadiazine, and trimethoprim were detected in environmental water samples in concentrations ranging from 1.26 to 127.49 ng/L. The developed method is a reliable analytical technique for the potential routine monitoring of veterinary antibiotics. Copyright © 2018 Elsevier B.V. All rights reserved.

Social defeat stress promotes tumor growth and angiogenesis by upregulating vascular endothelial growth factor/extracellular signal-regulated kinase/matrix metalloproteinase signaling in a mouse model of lung carcinoma.

PubMed

Wu, Xiao; Liu, Bao-Jun; Ji, Shumeng; Wu, Jing-Feng; Xu, Chang-Qing; Du, Yi-Jie; You, Xiao-Fang; Li, Bei; Le, Jing-Jing; Xu, Hai-Lin; Duan, Xiao-Hong; Dong, Jing-Cheng

2015-07-01

Numerous epidemiological and experimental animal studies have indicated that chronic psychological stress may promote tumor development. However, the underlying molecular mechanisms by which chronic stress promotes tumorigenesis remain to be fully elucidated and animal models have not yet been well established. In the present study, an established mouse model of repeated social defeat stress (RSDS), was generated and used to investigate the effect of stress on tumor growth and metastasis. C57BL/6 mice were exposed to RSDS for 10 days, followed by subcutaneousl inoculation with Lewis lung carcinoma cells for seven days. The tumor weight and volume as well as the number of the lung metastatic nodules were then determined. Vascular endothelial growth factor (VEGF) serum levels were measured using ELISAs. In addition, expression levels of VEGF receptor (VEGFR) and L1 cell adhesion molecule (L1CAM) messenger (m)RNA were confirmed using reverse transcription quantitative polymerase chain reaction. Furthermore, protein expression levels of phosphorlyated extracellular signal-regulated kinase (pERK), matrix metalloproteinase (MMP)-2 and MMP-9 were examined using western blot analysis. The results showed that RSDS significantly increased the weight and the volume of the primary tumor as well as the number of the lung metastatic nodules. Serum VEGF levels were significantly higher in the tumor-stress group compared with those of the unstressed tumor mice. In addition, tumors in stressed animals demonstrated markedly enhanced expression of VEGFR-2 and L1CAM mRNA as well as pERK, MMP-2 and MMP-9 protein expression. In conclusion, these results suggested that RSDS contributed to lung cancer progression, angiogenesis and metastasis, which was partially associated with increased VEGF secretion and therefore the activation of the ERK signaling pathway, resulting in the induction of MMP-2 and MMP-9 protein expression.

Choline in infant formula and adult nutritionals by ion chromatography and suppressed conductivity: First Action 2012.20.

PubMed

Oates, Kassandra; Chen, Lillian; De Borba, Brian; Mohindra, Deepali; Rohrer, Jeffrey; Dowell, Dawn

2013-01-01

Single-laboratory validation (SLV) data from a method for the determination of choline in infant formula and adult nutritionals by ion chromatography (IC) and suppressed conductivity were generated and presented to the Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) Expert Review Panel (ERP) at the AOAC Annual Meeting held in Las Vegas, NV, during September 30 to October 3, 2012. The ERP reviewed the data and concluded that the data met the standard method performance requirements (SMPRs) established and approved the method as AOAC Official First Action. At the ERP's request, a second, full SLV was performed on 17 SPIFAN matrixes that included fortified and placebo products. Prior to IC analysis, microwave-assisted acid hydrolysis was used to digest and release bound choline from powder and ready-to-feed (RTF) infant formula and adult nutritional samples. Following hydrolysis, separation of choline from common cations was achieved on a Thermo Scientific Dionex IonPac CS19 column followed by suppressed conductivity detection. Total choline was measured and reported as the choline ion in mg/100 g reconstituted material or RTF as-is. The system was calibrated over the analytical range specified in the SMPR (2-250 mg/100 g). Recoveries of spiked samples at 50 and 100% of the fortified choline amounts ranged from 93.1 to 100.7% with RSDs < or = 6.7% for product containing < 2 mg/100 g and < or = 4.1% for product containing 2-100 mg/100 g. Accuracy for the National Institute of Standards and Technology Standard Reference Material 1849a was determined over a 6-day interval and found to be 10.2 +/- 0.2 mg/100 g calculated as the reconstituted powder with an RSD of 1.8%. The LOD was determined to be 0.009, and the LOQ 0.012 mg/100 g, well below the SMPR requirements of 0.7 and 2 mg/100 g, respectively. Repeatability RSDs over the range of the assay (2-200 mg/100 g) ranged from 1.0 to 5.93%

Simultaneous determination of creatinine, creatine, and UV-absorbing amino acids using dual-mode gradient low-capacity cation-exchange chromatography.

PubMed

Yokoyama, Yukio; Tsuji, Sachiyo; Sato, Hisakuni

2005-08-26

A simple and versatile cation-exchange chromatography technique for the simultaneous determination of urinary creatinine (Cre), creatine (Crn), methionine (Met), tyrosine (Tyr), phenylalanine (Phe), histidine (His), and tryptophan (Trp) was developed. A novel low-capacity cation-exchange column packed with a newly developed sulfoacylated hypercross-linked macroreticular polystyrene-divinylbenzene resin, referred to as TMR-A/75 (capacity: 75 microequiv/column), was successfully used with a binary dual-mode gradient eluting system. Two solvents, (A) 25 mM phosphoric acid-methanol (30:70, v/v) and (B) 25 mM disodium hydrogenphosphate-methanol (30:70, v/v) were pumped through the column by programming solvent delivery ratios as 0 to 5 min: A-B (55:45, pH 3.6); 5-21 min: A-B (49:51, pH 5.3); and 21-35 min: A-B (55:45, pH 3.6). The flow rate was simultaneously time-programmed to be 0.6 mL/min from 0 to 19 min and to be 1.0 mL/min from 19 to 35 min. This eluting system could permit the use of the UV detection at 210 nm. The analytes, Crn, Met, Tyr, His, Cre, Phe, and Trp, were well separated in this order in 27 min with minimum resolution of approximately 2, and the cycle time was about 35 min. Retention time of each analyte was very reproducible with relative standard deviations (RSDs) between 0.05 and 0.38% (n = 5). The peak area responses were also reproducible with RSDs between 0.74 and 2.24% (n = 5). Calibration lines based on area data were linear from 1 to 1000 microM with r2 values of 0.9998 (Crn), 0.9998 (Met), 0.9999 (Tyr), 0.9999 (His), 1.0000 (Cre), 1.0000 (Phe), and 0.9999 (Trp). The method was applicable to the screening and/or chemical diagnosis of inherited metabolic disorders such as phenylketonuria (PKU), tyrosinemia, and Lowe syndrome. The creatinine ratios of diagnostic markers (microM/microM Cre) were easily determined. The Phe/Cre ratios for five urines from patients with PKU ranged from 0.162 to 0.521, and the Tyr/Cre ratio for tyrosinemia was 0.147. The ratios of Tyr/Cre, Phe/Cre, and Trp/Cre for Lowe syndrome were 0.497, 0.321, and 0.495, respectively. In contrast, the creatinine ratios for healthy newborns showed one digit lower than those for patients did. The developed method is very practical and can provide useful information and results for the clinical or biomedical researches with low analytical run costs.

Repeatability of the efficiency of columns packed with sub-3μm core-shell particles: Part III. 2.7μm Poroshell 120 EC-C18 particles in 4.6mm and 2.1mm × 100mm column formats.

PubMed

Gritti, Fabrice; Guiochon, Georges

2012-08-24

As part of an investigation of the column-to-column repeatability of the efficiency of columns packed with sub-3μm shell particles, the parameters of the mass transfer kinetics of twelve columns packed with the same batch of 2.7μm Poroshell 120 EC-C(18) particles (Agilent Technologies, Little Fall, DE, USA) were sequentially measured, using columns provided by the manufacturers that were representative of the efficiency distribution given by the quality test control. The reduced longitudinal diffusion term (B) was measured using the peak parking (PP) method; the reduced solid-liquid mass transfer resistance term (C) was given by a combination of the PP results and the most accurate model of effective diffusion in ternary composite materials. The overall eddy diffusion term (A) was obtained by subtraction of these two HETP terms from the overall reduced HETP derived from the peak moments measured by numerical integration of the entire peak profiles. The results demonstrate that the dispersion of the column efficiencies is a result of the random nature of the packing process and the eddy diffusion term resulting from the lack of homogeneity of the column bed. At the highest reduced velocity achieved for small analytes, the relative standard deviations (RSD) of the eddy diffusion term for the 2.1mm I.D. columns were ca. 3 and 11% (with average values h(eddy)= 2.5 and 13.5) for naphthalene (k=3) and uracil (k=0), respectively. For the 4.6mm I.D. columns, these RSDs were 5 and 13%, respectively, with average values h(eddy)= 1.4 and 2.9. For insulin at reduced velocities as high as 160, the RSDs of the total reduced plate heights were 3 and 8% for the 2.1 and 4.6mm I.D. columns, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Simultaneous determination of neonicotinoid insecticides in human serum and urine using diatomaceous earth-assisted extraction and liquid chromatography-tandem mass spectrometry.

PubMed

Yamamuro, Tadashi; Ohta, Hikoto; Aoyama, Mika; Watanabe, Daisuke

2014-10-15

A rapid and sensitive analytical method was developed for simultaneous determination of eight neonicotinoid insecticides (acetamiprid, clothianidin, dinotefuran, flonicamid, imidacloprid, nitenpyram, thiacloprid and thiamethoxam) and three specific metabolites of acetamiprid (N-desmethylacetamiprid, 5-(N-acetyl-N-methylaminomethyl)-2-chloropyridine and 5-(N-acetylaminomethyl)-2-chloropyridine) in human serum and urine. A diatomaceous earth-assisted extraction using Extrelut NT3 column with chloroform/2-propanol (3:1, v/v) as eluent was selected for the single step cleanup procedure for all the target compounds. Qualitative and quantitative analyses were conducted by liquid chromatography-tandem mass spectrometry with multiple reaction monitoring mode. The limits of detection and the limits of quantification of eleven compounds were in the ranges of 0.1-0.2ng/mL and 0.5-10ng/mL for serum, 0.1-1ng/mL and 1-10ng/mL for urine, respectively. The extraction recoveries were between 80.9% and 101.8% for serum samples, 91.9% and 106% for urine samples. The intra-day RSDs and the inter-day RSDs were less than 11.5% and 13.2% for serum, less than 8.3% and 8.8% for urine. The proposed procedure will be suitable for forensic investigations of human poisoning cases with neonicotinoid insecticides. This is the first report of simultaneous determination of eight neonicotinoids in serum and urine samples. Copyright © 2014. Published by Elsevier B.V.

Switch-on fluorescent strategy based on crystal violet-functionalized CdTe quantum dots for detecting L-cysteine and glutathione in water and urine.

PubMed

Sheng, Zhen; Chen, Ligang

2017-10-01

The concentration of L-cysteine (Cys) and glutathione (GSH) is closely related to the critical risk of various diseases. In our study, a new rapid method for the determination of Cys and GSH in water and urine samples has been developed using a fluorescent probe technique, which was based on crystal violet (CV)-functionalized CdTe quantum dots (QDs). The original QDs emitted fluorescence light, which was turned off upon adding CV. This conjugation of CV and QDs could be attributed to electrostatic interaction between COO - of mercaptopropionic acid (MPA) on the surface of QDs and N + of CV in aqueous solution. In addition, Förster resonance energy transfer (FRET) also occurred between CdTe QDs and CV. After adding Cys or GSH to the solution, Cys or GSH exhibited a stronger binding preference toward Cd 2+ than Cd 2+ -MPA, which disturbed the interaction between MPA and QDs. Thus, most MPA was able to be separated from the surface of QDs because of the participation of Cys or GSH. Then, the fluorescence intensity of the CdTe QDs was enhanced. Good linear relationships were obtained in the range of 0.02-40 μg mL -1 and 0.02-50 μg mL -1 , and the detection limits were calculated as 10.5 ng mL -1 and 8.2 ng mL -1 , for Cys and GSH, respectively. In addition, the concentrations of biological thiols in water and urine samples were determined by the standard addition method using Cys as the standard; the quantitative recoveries were in the range of 97.3-105.8%, and relative standard deviations (RSDs) ranged from 2.5 to 3.7%. The method had several unique properties, such as simplicity, lower cost, high sensitivity, and environmental acceptability. Graphical abstract Crystal violet-functionalized CdTe quantum dots for detecting L-cysteine and glutathione with switch-on fluorescent strategy.

A sublimate sorbent for stir-bar sorptive extraction of aqueous endocrine disruptor pesticides for gas chromatography-electron capture detection.

PubMed

Huang, Yu-Wen; Lee, Hua Kwang; Shih, Hou-Kuang; Jen, Jen-Fon

2018-06-06

A dumbbell-shaped magnetic stir-bar with sublimate sorbent was prepared for the stir bar sorptive extraction (SBSE) of pesticides in an aqueous sample prior to gas chromatography-micro-electron capture detection (GC-μECD). Cyclododecane (CDD) was coated onto a magnetic stir-bar surface as a sublimate sorbent, and steel balls were placed on both ends to form a dumbbell-shaped magnetic stir-bar for SBSE. Four EDC pesticides including chlorpyrifos, ethion, bromopropylate, and λ-cyhalothrin in aqueous samples were selected as model species to examine the proposed SBSE and the following desorption. The parameters studied were those affecting the extraction efficiencies including the coating (solvent for CDD and thickness), extraction (sample pH, stirring rate, time, and salting out effect), dissolution solvent volume, and the loss of CDD sublimated in air. The maximum extraction efficiency was obtained under the following conditions. The stir bar (with CDD thickness of 5.2 μm) was added into a 10 mL sample solution (at pH 7) for a 20-min extraction at 600 rpm. Then, the stir bar was gently removed from the sample solution, disassembled, and immersed into a 0.2 mL insert tube consisting of 3 μL hexane to dissolve; 1 μL was used for GC-ECD analysis. The linear ranges were 0.005-5 μg L -1 with coefficients of determination ranging from 0.9950 - 0.9994. Detection limits (based on S/N = 3) of the four EDCs were 0.4-4.5 ngL -1 with a relative standard deviation (RSD) of 2.4-6.3%, and quantitation limits (based on S/N = 5) were 1-15 ngL -1 . The relative recoveries of the spiked samples were in the range of 83.2-98.7% with RSDs of 2.1-8.4% in farm field waters. The proposed sublimation sorbent obtained excellent enrichment factors (101-834) and provided a simple, rapid, sensitive, and eco-friendly sample preparation method. Copyright © 2018 Elsevier B.V. All rights reserved.

Dithizone modified magnetic nanoparticles for fast and selective solid phase extraction of trace elements in environmental and biological samples prior to their determination by ICP-OES.

PubMed

Cheng, Guihong; He, Man; Peng, Hanyong; Hu, Bin

2012-01-15

A fast and simple method for analysis of trace amounts of Cr(III), Cu(II), Pb(II) and Zn(II) in environmental and biological samples was developed by combining magnetic solid phase extraction (MSPE) with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection. Dithizone modified silica-coated magnetic Fe(3)O(4) nanoparticles (H(2)Dz-SCMNPs) were prepared and used for MSPE of trace amounts of Cr(III), Cu(II), Pb(II) and Zn(II). The prepared magnetic nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The factors affecting the extraction of the target metal ions such as pH, sample volume, eluent, and interfering ions had been investigated and the adsorption mechanism of the target metals on the self-prepared H(2)Dz-SCMNPs was investigated by FT-IR and X-ray photo electron spectroscopy (XPS). Under the optimized conditions, the detection limits of the developed method for Cr(III), Cu(II), Pb(II) and Zn(II) were 35, 11, 62, and 8ngL(-1), respectively, with the enrichment factor of 100. The relative standard deviations (RSDs, c=10μgL(-1), n=7) were in the range of 1.7-3.1% and the linear range was 0.1-100μgL(-1). The proposed method had been validated by two certified reference materials (GSBZ50009-88 environmental water and GBW07601 human hair), and the determined values were in good agreement with the certified values. The method was also applied for the determination of trace metals in real water and human hair samples with recoveries in the range of 85-110% for the spiked samples. The developed MSPE-ICP-OES method has the advantages of simplicity, rapidity, selectivity, high extraction efficiency and is suitable for the analysis of samples with large volume and complex matrix. Copyright © 2011 Elsevier B.V. All rights reserved.

A rapid method based on hot water extraction and liquid chromatography-tandem mass spectrometry for analyzing tetracycline antibiotic residues in cheese.

PubMed

Bogialli, Sara; Coradazzi, Cristina; Di Corcia, Antonio; Lagana, Aldo; Sergi, Manuel

2007-01-01

A rapid, specific, and sensitive procedure for determining residues of 4 widely used tetracycline antibiotics and 3 of their 4-epimers in cheese is presented. The method is based on the matrix solid-phase dispersion (MSPD) technique followed by liquid chromatography/tandem mass spectrometry (LC/MS/MS). After dispersing samples of mozzarella, asiago, parmigiano, gruyere, emmenthal, and camembert on sand, target compounds were eluted from the MSPD column by passing through it 6 mL water heated at 70 degrees C. After acidification and filtration, 200 microL of the aqueous extract was directly injected into the LC column. For analyte identification and quantification, MS data acquisition was performed in the multireaction monitoring mode, selecting 2 precursor ion-to-product ion transitions for each target compound. Hot water appeared to be an efficient extractant, because absolute recoveries were no lower than 78%. Using demeclocycline as a surrogate analyte, recoveries of analyte added to the 6 types of cheeses at the 30 ng/g level were 96-117%, with relative standard deviation (RSD) not higher than 9%. Statistical analysis of the mean recovery data showed that the extraction efficiency was not dependent on the type of cheese analyzed. This result indicates that this method could be applied to other cheese types not considered here. At the lowest concentration considered, i.e., 10 ng/g, the accuracy of the method ranged between 90 and 107%, with RSDs not larger than 12%. Based on a signal-to-noise ratio of 10, limits of quantitation were estimated to be 1-2 ng/g.

Simultaneous qualitative and quantitative determination of phenolic compounds in Aloe barbadensis Mill by liquid chromatography-mass spectrometry-ion trap-time-of-flight and high performance liquid chromatography-diode array detector.

PubMed

Wu, Xiaofang; Ding, Wenjing; Zhong, Jiasheng; Wan, Jinzhi; Xie, Zhiyong

2013-06-01

An effective and comprehensive method was developed for the simultaneous analysis of phenolic compounds in the dried exudate of Aloe barbadensis Mill by liquid chromatography-mass spectrometry-ion trap-time-of-flight (LCMS-IT-TOF) and high performance liquid chromatography-diode array detector (HPLC-DAD). Qualitative analysis of all the compounds presented in A. barbadensis Mill was performed on LCMS-IT-TOF, and the diagnostic fragmentation patterns of different types of phenolic compounds (chromones, phenyl pyrones, naphthalene derivative, anthrones and anthraquinones) were discussed on the basis of ESI-IT-TOF MS of components in A. barbadensis Mill and eleven authentic standards. Under the optimal HPLC-DAD chromatographic conditions, quantification of 11 typical phenolic compounds in 15 batches of A. barbadensis Mill was achieved on an Agilent TC-C18 column using gradient elution with a solvent system of methanol and water at a flow rate of 1.0mLmin(-1) and detected at 230nm. All calibration curves exhibited good linear relationship (r(2)>0.9991). The relative standard deviation values for intraday precision were less than 2% with accuracies between 98.21% and 104.57%. The recoveries of the eleven analytes ranged from 97.53 to 105.00% with RSDs less than 2%. This is the first simultaneous characterization and quantitative determination of multiple phenolic compounds in A. barbadensis Mill from locally grown cultivars in China by LCMS-IT-TOF and HPLC-DAD, which can be applied to standardize the quality of A. barbadensis Mill and the future design of nutraceutical and cosmetic preparations. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous Quantification of Seven Bioactive Flavonoids in Citri Reticulatae Pericarpium by Ultra-Fast Liquid Chromatography Coupled with Tandem Mass Spectrometry.

PubMed

Zhao, Lian-Hua; Zhao, Hong-Zheng; Zhao, Xue; Kong, Wei-Jun; Hu, Yi-Chen; Yang, Shi-Hai; Yang, Mei-Hua

2016-05-01

Citri Reticulatae Pericarpium (CRP) is a commonly-used traditional Chinese medicine with flavonoids as the major bioactive components. Nevertheless, the contents of the flavonoids in CRP of different sources may significantly vary affecting their therapeutic effects. Thus, the setting up of a reliable and comprehensive quality assessment method for flavonoids in CRP is necessary. To set up a rapid and sensitive ultra-fast liquid chromatography coupled with tandem mass spectrometry (UFLC-MS/MS) method for simultaneous quantification of seven bioactive flavonoids in CRP. A UFLC-MS/MS method coupled to ultrasound-assisted extraction was developed for simultaneous separation and quantification of seven flavonoids including hesperidin, neohesperidin, naringin, narirutin, tangeretin, nobiletin and sinensetin in 16 batches of CRP samples from different sources in China. The established method showed good linearity for all analytes with correlation coefficient (R) over 0.9980, together with satisfactory accuracy, precision and reproducibility. Furthermore, the recoveries at the three spiked levels were higher than 89.71% with relative standard deviations (RSDs) lower than 5.19%. The results indicated that the contents of seven bioactive flavonoids in CRP varied significantly among different sources. Among the samples under study, hesperidin showed the highest contents in 16 samples ranged from 27.50 to 86.30 mg/g, the contents of hesperidin in CRP-15 and CRP-9 were 27.50 and 86.30 mg/g, respectively, while, the amount of narirutin was too low to be measured in some samples. This study revealed that the developed UFLC-MS/MS method was simple, sensitive and reliable for simultaneous quantification of multi-components in CRP with potential perspective for quality control of complex matrices. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Simultaneous, stability indicating, HPLC-DAD determination of guaifenesin and methyl and propyl-parabens in cough syrup.

PubMed

Grosa, Giorgio; Del Grosso, Erika; Russo, Roberta; Allegrone, Gianna

2006-06-07

A stability indicating high performance liquid chromatography procedure has been developed for the simultaneous determination of guaifenesin (GUA), methyl p-hydroxybenzoate (MHB) and propyl p-hydroxybenzoate (PHB) in a commercial cough syrup dosage form. The method was specific and stability indicating as chromatographic conditions were selected to provide adequate separation of GUA, MHB and PHB from the putative degradation products guaiacol (GUAI) and p-hydroxybenzoic acid (HBA) as well as from excipients. The isocratic separation and quantitation were achieved within 17 min on a 150-mm column with an ether-linked phenyl stationary phase and a hydrophilic endcapping. The mobile phase was constituted of eluant A: aqueous phosphate buffer (pH 3.0, 10 mM)/acetonitrile 25/75 (v/v) and eluant B:methanol; the A:B ratio was 85:15 (v/v) with a flow rate 1 ml min-1 and detection of analytes at 254 and 276 nm. The method showed good linearity for the GUA-MHB-PHB mixture in the 95-285, 4-12, and 1-3 microg ml-1 ranges, respectively, being all the square of the correlation coefficients greater than 0.999. The interday R.S.D.s were 1.17, 1.14, and 0.91%, for GUA, MHB, and PHP, respectively. The method demonstrated also to be accurate; indeed the average recoveries, at 100% of the target assay concentration, were 100.5, 100.3, and 100.7% with relative standard deviations of 0.8, 0.7, and 0.4% for GUA, MHB, and PHB, respectively, from laboratory prepared samples. The applicability of the method was evaluated in commercial dosage form analysis as well as in stability studies.

Simultaneous quantification of endogenous and exogenous plasma glucose by isotope dilution LC-MS/MS with indirect MRM of the derivative tag.

PubMed

Yu, Lingling; Wen, Chao; Li, Xing; Fang, Shiqi; Yang, Lichuan; Wang, Tony; Hu, Kaifeng

2018-03-01

Quantification of endogenous and exogenous plasma glucose can help more comprehensively evaluate the glucose metabolic status. A ratio-based approach using isotope dilution liquid chromatography tandem mass spectrometry (ID LC-MS/MS) with indirect multiple reaction monitoring (MRM) of the derivative tag was developed to simultaneously quantify endo-/exogenous plasma glucose. Using diluted D-[ 13 C 6 ] glucose as tracer of exogenous glucose, 12 C 6 / 13 C 6 glucoses were first derivatized and then data were acquired in MRM mode. The metabolism of exogenous glucose can be tracked and the concentration ratio of endo/exo-genous glucose can be measured by calculating the endo-/exo-genous glucose concentrations from peak area ratio of specific daughter ions. Joint application of selective derivatization and MRM analysis not only improves the sensitivity but also minimizes the interference from the background of plasma, which warrants the accuracy and reproducibility. Good agreement between the theoretical and calculated concentration ratios was obtained with a linear correlation coefficient (R) of 0.9969 in the range of D-glucose from 0.5 to 20.0 mM, which covers the healthy and diabetic physiological scenarios. Satisfactory reproducibility was obtained by evaluation of the intra- and inter-day precisions with relative standard deviations (RSDs) less than 5.16%, and relative recoveries of 85.96 to 95.92% were obtained at low, medium, and high concentration, respectively. The method was successfully applied to simultaneous determination of the endo-/exogenous glucose concentration in plasma of non-diabetic and type II diabetic cynomolgus monkeys. Graphical Abstract The scheme of the proposed ratio-based approach using isotope dilution LC-MS/MS with indirect MRM of the derivative tag for simultaneous quantification of endogenous and exogenous plasma glucose.

Fabrication of magnetic microsphere-confined graphene for the preconcentration of some phthalate esters from environmental water and soybean milk samples followed by their determination by HPLC.

PubMed

Wang, Weina; Ma, Ruiyang; Wu, Qiuhua; Wang, Chun; Wang, Zhi

2013-05-15

In this study, a magnetic microsphere-confined graphene (Fe3O4@SiO2-G) was prepared as a novel adsorbent for the preconcentration of some phthalate esters in environmental water and soybean milk samples prior to high performance liquid chromatography analysis. The properties and morphology of the Fe3O4@SiO2-G were characterized by transmission electron microscopy and X-ray diffraction. This novel graphene-based magnetic nanocomposite showed great adsorptive ability toward the analytes. The method, which takes the advantages of both the high adsorption capacity of G and easy phase separation of the magnetic adsorbent from the sample solution, could avoid the time-consuming experimental procedures related to the traditional solid phase extraction. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe3O4@SiO2-G, the extraction time, the pH of sample solution and the desorption conditions, were investigated. Under the optimum conditions, the limits of detection (S/N=3) of the method for the compounds were between 0.07 and 0.10 ng mL(-1) in water samples, and between 0.15 and 0.30 ng mL(-1) in soybean milk samples. The relative standard deviations (RSDs) varied from 2.7% to 6.1% (n=5). The recoveries of the method were in the range between 87.2% and 109.0% for environmental water and soybean milk samples. The method is suitable to determine the five phthalate esters (diallyl phthalate, di-n-propyl-phthalate, benzyl butyl phthalate, dicyclohexyl-phthalate and diethyl-hexyl-phthalate) in environmental water and soybean milk samples. Copyright © 2013 Elsevier B.V. All rights reserved.

A method for the analysis of perfluorinated compounds in environmental and drinking waters and the determination of their lowest concentration minimal reporting levels.

PubMed

Boone, J Scott; Guan, Bing; Vigo, Craig; Boone, Tripp; Byrne, Christian; Ferrario, Joseph

2014-06-06

A trace analytical method was developed for the determination of seventeen specific perfluorinated chemicals (PFCs) in environmental and drinking waters. The objectives were to optimize an isotope-dilution method to increase the precision and accuracy of the analysis of the PFCs and to eliminate the need for matrix-matched standards. A 250 mL sample of environmental or drinking water was buffered to a pH of 4, spiked with labeled surrogate standards, extracted through solid phase extraction cartridges, and eluted with ammonium hydroxide in methyl tert-butyl ether: methanol solution. The sample eluents were concentrated to volume and analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The lowest concentration minimal reporting levels (LCMRLs) for the seventeen PFCs were calculated and ranged from 0.034 to 0.600 ng/L for surface water and from 0.033 to 0.640 ng/L for drinking water. The relative standard deviations (RSDs) for all compounds were <20% for all concentrations above the LCMRL. The method proved effective and cost efficient and addressed the problems with the recovery of perfluorobutanoic acid (PFBA) and other short chain PFCs. Various surface water and drinking water samples were used during method development to optimize this method. The method was used to evaluate samples from the Mississippi River at New Orleans and drinking water samples from a private residence in that same city. The method was also used to determine PFC contamination in well water samples from a fire training area where perfluorinated foams were used in training to extinguish fires. Published by Elsevier B.V.

Preparation of styrene-co-4-vinylpyridine magnetic polymer beads by microwave irradiation for analysis of trace 24-epibrassinolide in plant samples using high performance liquid chromatography.

PubMed

Zhang, Zhuomin; Zhang, Yi; Tan, Wei; Li, Gongke; Hu, Yuling

2010-10-15

In the study, a kind of novel styrene-co-4-vinylpyridine (St-co-4-VP) porous magnetic polymer beads was prepared by microwave irradiation using suspension polymerization. Microwave heating preparation greatly reduced the polymerization time to 1h. Physical characteristic tests suggested that these beads were cross-linking and possessed spherical shape, good magnetic response and porous morphologies with a narrow diameter distribution of 70-180 μm. Therefore, these beads displayed the long-term stability after undergoing 100-time extractions. Then, an analytical method for the determination of trace 24-epiBR in plant samples was developed by magnetic polymer bead extraction coupled with high performance liquid chromatography-fluorescence detection. St-co-4-VP magnetic polymer beads demonstrated the higher extraction selectivity for 24-epiBR than other reference compounds. Linear range was 10.00-100.0 μg/L with a relative standard deviation (RSD) of 6.7%, and the detection limit was 6.5 μg/kg. This analytical method was successfully applied to analyze the trace 24-epiBR in cole and breaking-wall rape pollen samples with recoveries of 77.2-90.0% and 72.3-83.4%, respectively, and RSDs were less than 4.1%. The amount of 24-epiBR in real breaking-wall rape pollen samples was found to be 26.2 μg/kg finally. This work proposed a sensitive, rapid, reliable and convenient analytical method for the determination of trace brassinosteroids in complicated plant samples by the use of St-co-4-VP magnetic polymer bead extraction coupled with chromatographic method. Copyright © 2010 Elsevier B.V. All rights reserved.

UNE-EN ISO/IEC 17025:2005-accredited method for the determination of pesticide residues in fruit and vegetable samples by LC-MS/MS.

PubMed

Camino-Sánchez, F J; Zafra-Gómez, A; Oliver-Rodríguez, B; Ballesteros, O; Navalón, A; Crovetto, G; Vílchez, J L

2010-11-01

A rapid, simple and sensitive multi-residue method was developed and validated for the simultaneous quantification and confirmation of 69 pesticides in fruit and vegetables using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted following the quick, easy, cheap, effective, rugged and safe method known as QuEChERS. Mass spectrometric conditions were individually optimised for each analyte in order to achieve maximum sensitivity in multiple reaction monitoring (MRM) mode. Using the developed chromatographic conditions, 69 pesticides can be separated in less than 17 min. Two selected reaction monitoring (SRM) assays were used for each pesticide to obtain simultaneous quantification and identification in one run. With this method in SRM mode, more than 150 pesticides can be analysed and quantified, but their confirmation is not possible in all cases according to the European regulations on pesticide residues. Nine common representative matrices (zucchini, melon, cucumber, watermelon, tomato, garlic, eggplant, lettuce and pepper) were selected to investigate the effect of different matrices on recovery and precision. Mean recoveries ranged from 70% to 120%, with relative standard deviations (RSDs) lower than 20% for all the pesticides. The proposed method was applied to the analysis of more than 2000 vegetable samples from the extensive greenhouse cultivation in the province of Almeria, Spain, during one year. The methodology combines the advantages of both QuEChERS and LC-MS/MS producing a very rapid, sensitive, accurate and reliable procedure that can be applied in routine analytical laboratories. The method was validated and accredited according to UNE-EN-ISO/IEC 17025:2005 international standard (accreditation number 278/LE1027).

Online analysis of five organic ultraviolet filters in environmental water samples using magnetism-enhanced monolith-based in-tube solid phase microextraction coupled with high-performance liquid chromatography.

PubMed

Mei, Meng; Huang, Xiaojia

2017-11-24

Due to the endocrine disrupting properties, organic UV filters have been a great risk for humans and other organisms. Therefore, development of accurate and effective analytical methods is needed for the determination of UV filters in environmental waters. In this work, a fast, sensitive and environmentally friendly method combining magnetism-enhanced monolith-based in-tube solid phase microextraction with high-performance liquid chromatography with diode array detection (DAD) (ME-MB-IT/SPME-HPLC-DAD) for the online analysis of five organic UV filters in environmental water samples was developed. To extract UV filters effectively, an ionic liquid-based monolithic capillary column doped with magnetic nanoparticles was prepared by in-situ polymerization and used as extraction medium of online ME-MB-IT/SPME-HPLC-DAD system. Several extraction conditions including the intensity of magnetic field, sampling and desorption flow rate, volume of sample and desorption solvent, pH value and ionic strength of sample matrix were optimized thoroughly. Under the optimized conditions, the extraction efficiencies for five organic UV filters were in the range of 44.0-100%. The limits of detection (S/N=3) and limits of quantification (S/N=10) were 0.04-0.26μg/L and 0.12-0.87μg/L, respectively. The precisions indicated by relative standard deviations (RSDs) were less than 10% for both intra- and inter-day variabilities. Finally, the developed method was successfully applied to the determination of UV filters in three environmental water samples and satisfactory results were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of chloramphenicol in milk powder using liquid-liquid cartridge extraction (Chem Elut) and liquid chromatography-tandem mass spectrometry.

PubMed

Zawadzka, Iwona; Rodziewicz, Lech

2014-01-01

The European Union prohibits the use of chloramphenicol (CAP) as a veterinary drug in food-producing animals. Nevertheless, CAP have been detected in milk products (liquid milk and milk powder). Therefore, it is necessary to develop sensitive methods for determining CAP residues in milk powder. The aim of this study was to develop and validate a confirmatory method for determination of CAP in milk powder. Chloramphenicol was determined in milk powder using LC-ESI-MS/MS in negative mode. After fat removing milk powder sample was extracted/cleaned-up with a Chem Elut extraction cartridge. Separation was achieved on a Phenomenex Luna C-18 column with acetonitrile-water as a mobile phase. The mass spectrometer was operated in multiple reaction monitoring mode (MRM). Four transitions were monitored m/z 321→152, 321→194, 321→257 (CAP) and 326→157 (IS CAP-d5). Linearity, accuracy, precision, decision limit (CCa), detection capability (CCb) and ruggedness were determined for m/z 321→152. The mean relative recoveries (inter standard-corrected) of CAP from whole milk powder spiked at levels 0.1, 0.2, 0.3 and 0.6 mg/kg were in the range 95 - 103%. Relative standard deviation (RSD%) of recoveries at all spiked levels were less than 14%. RSDs within-laboratory reproducibility calculated at fortification of 0.3 mg/kg was less than 16%. CCa and CCb were below 0.1 mg/kg. The developed LC-MS/MS method allows the determination of CAP in milk powder. The method was validated according to the Commission Decision No. 2002/657/EC requirements. This method can be applied to determination CAP in whole and skim milk powder.

Development and comparison of HPLC-MS/MS and UPLC-MS/MS methods for determining eight coccidiostats in beef.

PubMed

Zhao, Xia; Wang, Bo; Xie, Kaizhou; Liu, Jianyu; Zhang, Yangyang; Wang, Yajuan; Guo, Yawen; Zhang, Genxi; Dai, Guojun; Wang, Jinyu

2018-06-15

A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method and an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determining eight coccidiostat (halofuginone, lasalocid, maduramicin, monensin, narasin, nigericin, robenidine and salinomycin) residues in beef were developed and compared. Samples were extracted with a mixture of acetic acid, acetonitrile and ethyl acetate and were then purified on a C 18 solid-phase extraction (SPE) column. The purified samples were analyzed by HPLC-MS/MS and UPLC-MS/MS, using 0.1% formic acid-water solution (A) and pure methanol (B) as the mobile phase. The samples were fractionated on a C 18 column using different gradient elution procedures, followed by qualitative analysis using a mass spectrometer operated in multiple reaction monitoring (MRM) mode with positive electrospray ionization; the external standard method was used for quantitation. At spiked levels that ranged from the limit of quantification (LOQ) to 100 μg/kg, the average recoveries were 71.96%-100.32% and 71.24%-89.24%, with relative standard deviations (RSDs) of 2.65%-12.38% and 2.98%-14.86% for UPLC-MS/MS and HPLC-MS/MS, respectively. The limits of detection (LODs) and LOQs of the eight coccidiostats were 0.14-0.32 μg/kg and 0.43-1.21 μg/kg, respectively, for UPLC-MS/MS analysis and 0.16-0.58 μg/kg and 0.53-1.92 μg/kg, respectively, for HPLC-MS/MS analysis. Both methods had good accuracy and precision, but UPLC-MS/MS had higher sensitivity than HPLC-MS/MS. Copyright © 2018 Elsevier B.V. All rights reserved.

Separation and preconcentration of riboflavin from human plasma using polythionine coated magnetite/hydroxyapatite nanocomposite prior to analysis by surfactant-enhanced fluorimetry

NASA Astrophysics Data System (ADS)

Farzin, Leila; Shamsipur, Mojtaba

2017-09-01

The exploration of novel adsorption properties of conductive polymers based on hybridization with biocompatible nanomaterials receives an increasing interest. In this regard, hydroxyapatite (HA) bioceramic is of critical importance mainly owing to its facile synthesis, high surface area, economic and low toxicity in biological environments. In this work, we first prepared and characterized a magnetite/hydroxyapatite (Fe3O4/HA) nanocomposite using the bio-waste chicken eggshell via an attractive green way that involved low cost and irrespective of toxicity. Then, polythionine as a novel class of conductive polymers was in situ coated on the synthesized magnetic bioceramic for the separation and preconcentration of riboflavin (vitamin B2) in human plasma before its fluorimetric determination. Considering the putative role of riboflavin in protecting against cancer and cardiovascular diseases, it is essential to evaluate this vitamin in biological fluids. The described method possesses a linear range of 0.75-262.5 μg L- 1 (R2 = 0.9985) and a detection limit of 0.20 μg L- 1 (signal-to-noise ratio of 3). The relative standard deviations (RSDs) for single-sorbent repeatability and sorbent-to-sorbent reproducibility were less than 4.0% and 7.6% (n = 5), respectively. The respective enrichment factor and extraction recovery of the method found to be 35.7 and 98.4%. The analytical performance of method for riboflavin was characterized by good consistency of the results with those obtained by the enzyme-linked immunosorbent assay (ELISA) conventional method (p-value of < 0.05). The optimized protocol intended for control determinations of riboflavin in human subjects and is addressed to clinical laboratories.

Ultrasound assisted extraction of Maxilon Red GRL dye from water samples using cobalt ferrite nanoparticles loaded on activated carbon as sorbent: Optimization and modeling.

PubMed

Mehrabi, Fatemeh; Vafaei, Azam; Ghaedi, Mehrorang; Ghaedi, Abdol Mohammad; Alipanahpour Dil, Ebrahim; Asfaram, Arash

2017-09-01

In this research, a selective, simple and rapid ultrasound assisted dispersive solid-phase micro-microextraction (UA-DSPME) was developed using cobalt ferrite nanoparticles loaded on activated carbon (CoFe 2 O 4 -NPs-AC) as an efficient sorbent for the preconcentration and determination of Maxilon Red GRL (MR-GRL) dye. The properties of sorbent are characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Vibrating sample magnetometers (VSM), Fourier transform infrared spectroscopy (FTIR), Particle size distribution (PSD) and Scanning Electron Microscope (SEM) techniques. The factors affecting on the determination of MR-GRL dye were investigated and optimized by central composite design (CCD) and artificial neural networks based on genetic algorithm (ANN-GA). CCD and ANN-GA were used for optimization. Using ANN-GA, optimum conditions were set at 6.70, 1.2mg, 5.5min and 174μL for pH, sorbent amount, sonication time and volume of eluent, respectively. Under the optimized conditions obtained from ANN-GA, the method exhibited a linear dynamic range of 30-3000ngmL -1 with a detection limit of 5.70ngmL -1 . The preconcentration factor and enrichment factor were 57.47 and 93.54, respectively with relative standard deviations (RSDs) less than 4.0% (N=6). The interference effect of some ions and dyes was also investigated and the results show a good selectivity for this method. Finally, the method was successfully applied to the preconcentration and determination of Maxilon Red GRL in water and wastewater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrokinetic gated injection-based microfluidic system for quantitative analysis of hydrogen peroxide in individual HepG2 cells.

PubMed

Zhang, Xinyuan; Li, Qingling; Chen, Zhenzhen; Li, Hongmin; Xu, Kehua; Zhang, Lisheng; Tang, Bo

2011-03-21

A microfluidic system to determine hydrogen peroxide (H(2)O(2)) in individual HepG2 cells based on the electrokinetic gated injection was developed for the first time. A home-synthesized fluorescent probe, bis(p-methylbenzenesulfonate)dichlorofluorescein (FS), was employed to label intracellular H(2)O(2) in the intact cells. On a simple cross microchip, multiple single-cell operations, including single cell injection, cytolysis, electrophoresis separation and detection of H(2)O(2), were automatically carried out within 60 s using the electrokinetic gated injection and laser-induced fluorescence detection (LIFD). The performance of the method was evaluated under the optimal conditions. The linear calibration curve was over a range of 4.39-610 amol (R(2)=0.9994). The detection limit was 0.55 amol or 9.0×10(-10) M (S/N=3). The relative standard deviations (RSDs, n=6) of migration time and peak area were 1.4% and 4.8%, respectively. With the use of this method, the average content of H(2)O(2) in single HepG2 cells was found to be 16.09±9.84 amol (n=15). Separation efficiencies in excess of 17,000 theoretical plates for the cells were achieved. These results demonstrated that the efficient integration and automation of these single-cell operations enabled the sensitive, reproducible, and quantitative examination of intracellular H(2)O(2) at single-cell level. Owing to the advantages of simple microchip structure, controllable single-cell manipulation and ease in building, this platform provides a universal way to automatically determine other intracellular constituents within single cells. This journal is © The Royal Society of Chemistry 2011

Effect of Sunlight Radiation on the Growth and Chemical Constituents of Salvia plebeia R.Br.

PubMed

Jang, Hyun-Jae; Lee, Seung-Jae; Kim, Cha Young; Hwang, Joo Tae; Choi, Jung Ho; Park, Jee Hun; Lee, Seung Woong; Rho, Mun-Chual

2017-08-01

This study investigated the chemical composition changes of Salvia plebeia R.Br. cultivated under different light sources, including florescent light and sunlight. The plants were exposed to fluorescent light for four months and sunlight and then examined for the next 5-7 months. Plants were harvested monthly during the seven months, and we examined whether the difference in light source affected the phenolic and flavonoid contents and antioxidant activity. A simple and reliable HPLC method using a PAH C 18 column was applied for the quantitative analysis of two triterpenoids from the S. plebeia groups. Oleanolic acid (OA) and ursolic acid (UA) showed good linearity ( R ² > 0.9999) within the test ranges (0.005-0.05 mg/mL), and the average percentage recoveries of the OA and UA were 95.1-104.8% and 97.2-107.1%, respectively. The intra- and inter-day relative standard deviations (RSDs) were less than 2.0%. After exposure to sunlight, the phenolic contents, including rosmarinic acid, showed a reduced tendency, whereas the flavonoid contents, including homoplantaginin and luteolin 7-glucoside, were increased. The content of the triterpenoids also showed an increased tendency under sunlight irradiation, but the variance was not larger than those of the phenolic and flavonoid contents. Among experimental groups, the group harvested at six months, having been exposed to sunlight for two months, showed the most potent antioxidant activity. Therefore, these results showed that the chemical composition and antioxidant activities of S. plebeia R.Br. was affected from environmental culture conditions, such as light source. Our studies will be useful for the development of functional materials using S. plebeia R.Br.

Quantification of bupivacaine hydrochloride and isoflupredone acetate residues in porcine muscle, beef, milk, egg, shrimp, flatfish, and eel using a simplified extraction method coupled with liquid chromatography-triple quadrupole tandem mass spectrometry.

PubMed

Cho, Sang-Hyun; Park, Jin-A; Zheng, Weijia; Abd El-Aty, A M; Kim, Seong-Kwan; Choi, Jeong-Min; Yi, Hee; Cho, Soo-Min; Afifi, Nehal A; Shim, Jae-Han; Chang, Byung-Joon; Kim, Jin-Suk; Shin, Ho-Chul

2017-10-15

In this study, a simple analytical approach has been developed and validated for the determination of bupivacaine hydrochloride and isoflupredone acetate residues in porcine muscle, beef, milk, egg, shrimp, flatfish, and eel using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A 0.1% solution of acetic acid in acetonitrile combined with n-hexane was used for deproteinization and defatting of all tested matrices and the target drugs were well separated on a Waters Xbridge™ C18 analytical column using a mobile phase consisting of 0.1% acetic acid (A) and 0.1% solution of acetic acid in methanol (B). The linearity estimated from six-point matrix-matched calibrations was good, with coefficients of determination ≥0.9873. The limits of quantification (LOQs) for bupivacaine hydrochloride and isoflupredone acetate were 1 and 2ngg -1 , respectively. Recovery percentages in the ranges of 72.51-112.39% (bupivacaine hydrochloride) and 72.58-114.56% (isoflupredone acetate) were obtained from three different fortification concentrations with relative standard deviations (RSDs) of <15.14%. All samples for the experimental work and method application were collected from the local markets in Seoul, Republic of Korea, and none of them tested positive for the target drugs. In conclusion, a simple method using a 0.1% solution of acetic acid in acetonitrile and n-hexane followed by LC-MS/MS could effectively extract bupivacaine hydrochloride and isoflupredone acetate from porcine muscle, beef, milk, egg, shrimp, flatfish, and eel samples. Copyright © 2017 Elsevier B.V. All rights reserved.

In-tube solid-phase microextraction based on NH2-MIL-53(Al)-polymer monolithic column for online coupling with high-performance liquid chromatography for directly sensitive analysis of estrogens in human urine.

PubMed

Luo, Xialin; Li, Gongke; Hu, Yufei

2017-04-01

In this work, a novel NH 2 -MIL-53(Al) incorporated poly(styrene-divinylbenzene-methacrylic acid) (poly(St-DVB-MAA)) monolith was prepared via chemical fabrication. Moreover, it has been efficiently applied to the in-tube solid-phase microextraction (SPME) for online coupling with high-performance liquid chromatography (HPLC) to the direct determination of five estrogens in human urine samples. The NH 2 -MIL-53(Al)-polymer monolith was suitable for in-tube SPME owing to its good permeability, high extraction efficiency, chemical stability, good reproducibility and long lifetime. The extraction conditions including extraction solvent, pH of sample solution, flow rate of extraction and desorption, and desorption volume were investigated. Under the optimum conditions, the enrichment factors were 180-304 and saturated amounts of extraction were 2326-21393 pmol for estriol, 17β-estradiol, estrone, ethinyl estradiol and progesterone, respectively. The adsorption mechanism was also explored which contributed to its strong extraction to target compounds. The proposed method had low limit of detection (2.0-40ng/L) and good linearity (with R 2 between 0.9908 and 0.9978). Four endogenous estrogens were detected in urine samples and the recoveries of all five analytes were ranged from 75.1-120% with relative standard deviations (RSDs) less than 8.7%. The results showed that the proposed online SPME-HPLC method based on NH 2 -MIL-53(Al)-polymer monolithic column was highly sensitive for directly monitoring trace amount of estrogens in human urine sample. Copyright © 2016 Elsevier B.V. All rights reserved.

Rapid determination of some beta-blockers in complicated matrices by tandem dispersive liquid-liquid microextraction followed by high performance liquid chromatography.

PubMed

Hemmati, Maryam; Asghari, Alireza; Bazregar, Mohammad; Rajabi, Maryam

2016-11-01

In this research work, an efficient tandem dispersive liquid-liquid microextraction (TDLLME) procedure coupled with high performance liquid chromatography-ultraviolet detection (HPLC-UV) was successfully applied for the determination of beta-blockers in human plasma and pharmaceutical wastewater samples. High clean-up and preconcentration factor are easily and rapidly feasible via this novel, cheap, and safe microextraction method, leading to high quality experimental data. It consists of two sequential dispersive liquid-liquid microextraction methods, accomplished via air/ultrasonic agitation and air agitation, respectively. In order to enrich the optimal values for the mentioned procedures, the Box-Behnken design (BBD) combined with the desirability function (DF) was used. The optimum values were found to be 11.0 % (w/v) of the salt amount, an initial pH value of 12.0, 103 μL of organic extractant phase, and 45 μL of aqueous extractant phase with pH value of 2.0, resulted in reasonable recovery percentages with a logical desirability. Under optimal experimental conditions, good linear ranges (3-2000 ng mL -1 for metoprolol and 2.5-2500 ng mL -1 for propranolol with the correlation of determinations (R 2 s) higher than 0.99) and low limits of detection (0.8 and 1.0 ng mL -1 for propranolol and metoprolol, respectively) were obtainable. Also, TDLLME-HPLC-UV provided good proper repeatabilities (relative standard deviations (RSDs) below 5.7 %, n = 3) and high enrichment factors (EFs) of 75-100. Graphical abstract TDLLME of beta-blockers from complicated matrices.

Air-assisted liquid-liquid microextraction by solidifying the floating organic droplets for the rapid determination of seven fungicide residues in juice samples.

PubMed

You, Xiangwei; Xing, Zhuokan; Liu, Fengmao; Zhang, Xu

2015-05-22

A novel air assisted liquid-liquid microextraction using the solidification of a floating organic droplet method (AALLME-SFO) was developed for the rapid and simple determination of seven fungicide residues in juice samples, using the gas chromatography with electron capture detector (GC-ECD). This method combines the advantages of AALLME and dispersive liquid-liquid microextraction based on the solidification of floating organic droplets (DLLME-SFO) for the first time. In this method, a low-density solvent with a melting point near room temperature was used as the extraction solvent, and the emulsion was rapidly formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent for ten times repeatedly using a 10-mL glass syringe. After centrifugation, the extractant droplet could be easily collected from the top of the aqueous samples by solidifying it at a temperature lower than the melting point. Under the optimized conditions, good linearities with the correlation coefficients (γ) higher than 0.9959 were obtained and the limits of detection (LOD) varied between 0.02 and 0.25 μgL(-1). The proposed method was applied to determine the target fungicides in juice samples and acceptable recoveries ranged from 72.6% to 114.0% with the relative standard deviations (RSDs) of 2.3-13.0% were achieved. Compared with the conventional DLLME method, the newly proposed method will neither require a highly toxic chlorinated solvent for extraction nor an organic dispersive solvent in the application process; hence, it is more environmentally friendly. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous determination of superoxide and hydrogen peroxide in macrophage RAW 264.7 cell extracts by microchip electrophoresis with laser-induced fluorescence detection.

PubMed

Li, Hongmin; Li, Qingling; Wang, Xu; Xu, Kehua; Chen, Zhenzhen; Gong, Xiaocong; Liu, Xin; Tong, Lili; Tang, Bo

2009-03-15

A method for the first time to simultaneously determine superoxide and hydrogen peroxide in macrophage RAW 264.7 cell extracts by microchip electrophoresis with laser-induced fluorescence detection (MCE-LIF) was developed. 2-Chloro-1,3-dibenzothiazolinecyclohexene (DBZTC) and bis(p-methylbenzenesulfonyl) dichlorofluorescein (FS), two probes that can be specifically derivatized by superoxide and hydrogen peroxide, respectively, were synthesized and used. Parameters influencing the derivatization and on-chip separation were optimized. With the use of a HEPES (20 mM, pH 7.4) running buffer, a 50 mm long separation channel, and a separation voltage of 1800 V, baseline separation was achieved within 48 s for the two derivatization products, DBZTC-oxide (DBO) and 2,7-dichlorofluorescein (DCF). The linearity ranges of the method were 0.08-5.0 and 0.02-5.0 microM with detection limits (signal-to-noise ratio = 3) of 10 nM (1.36 amol) and 5.6 nM (0.76 amol) for superoxide and hydrogen peroxide, respectively. The relative standard deviations (RSDs) of migration time and peak area were less than 2.0% and 5.0%, respectively. The recoveries of the cell extract samples spiked with 1.0 microM standard solutions were 96.1% and 93.0% for superoxide and hydrogen peroxide, respectively. With the use of this method, superoxide and hydrogen peroxide in phorbol myristate acetate (PMA)-stimulated macrophage RAW 264.7 cell extracts were found to be 0.78 and 1.14 microM, respectively. The method has paved a way for simultaneously determining two or more reactive oxygen species (ROS) in a biological system with high resolution.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Li; Zhu, Zihua; Yu, Xiao-Ying

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a unique surface analysis technique because it can provide molecular recognition for organic and biological molecules. However, analyzing aqueous solution surfaces by ToF-SIMS is difficult, because ToF-SIMS is a high-vacuum technique, while the vapor pressure of water is about 2.3 kPa at room temperature (20 C). We designed and fabricated a self-contained microfluidic device, enabling in situ analysis of aqueous surfaces by scanning electron microscope (SEM) and ToF-SIMS, which has been briefly reported.1,2 In this study, we report more performance data, focusing on the performance of this device for in situ analysis ofmore » organic molecules at aqueous surfaces using ToF-SIMS. Three representative organic compounds (formic acid, glycerol, and glutamic acid) were tested, and their molecular signals were successfully observed. The device can be self-running in vacuum for 8 hours, and SIMS measurements are feasible at any time in this time range. The stability of this device under primary ion beam bombardment is also impressive. High fluence (6 × 1012 ions cm-2 s-1) measurements can be operated continuously for up to 30 minutes without any significant damage to the aperture. However, extra-high fluence measurements (>1 × 1014 ions cm-2 s-1) may lead to liquid bumping in the aperture, and the aqueous solutions may spread out quickly. Signal reproducibility is reasonably good, and relative standard deviation (RSD) for molecular ion signals can be controlled to be smaller than ±15% for consecutive measurements. Measurements at long time intervals (e.g., 60 min) show RSDs of ±40-50%. In addition, the detection limits of formic acid, glycerol, and glutamic acid are estimated to be 0.04%, 0.008%, and 0.002% (weight ratio), respectively.« less

Dissipation and distribution behavior of azoxystrobin, carbendazim, and difenoconazole in pomegranate fruits.

PubMed

Utture, Sagar C; Banerjee, Kaushik; Dasgupta, Soma; Patil, Sangram H; Jadhav, Manjusha R; Wagh, Sameer S; Kolekar, Sanjay S; Anuse, Mansing A; Adsule, Pandurang G

2011-07-27

The dissipation behavior and degradation kinetics of azoxystrobin, carbendazim, and difenoconazole in pomegranate are reported. Twenty fruits/hectare (5 kg) were collected at random, ensuring sample-to-sample relative standard deviation (RSD) within 20-25%. Each fruit was cut into eight equal portions, and two diagonal pieces per fruit were drawn and combined to constitute the laboratory sample, resulting in RSDs <6% (n = 6). Crushed sample (15 g) was extracted with 10 mL of ethyl acetate (+ 10 g Na(2)SO(4)), cleaned by dispersive solid phase extraction on primary secondary amine (25 mg) and C(18) (25 mg), and measured by liquid chromatography tandem mass spectrometry. The limit of quantification was ≤0.0025 μg g(-1) for all the three fungicides, with calibration linearity in the concentration range of 0.001-0.025 μg mL(-1) (r(2) ≥ 0.999). The recoveries of each chemical were 75-110% at 0.0025, 0.005, and 0.010 μg g(-1) with intralaboratory Horwitz ratio <0.32 at 0.0025 μg g(-1). Variable matrix effects were recorded in different fruit parts viz rind, albedo, membrane, and arils, which could be correlated to their biochemical constituents as evidenced from accurate mass measurements on a Q-ToF LC-MS. The residues of carbendazim and difenoconazole were confined within the outer rind of pomegranate; however, azoxystrobin penetrated into the inner fruit parts. The dissipation of azoxystrobin, carbendazim, and difenoconazole followed first + first order kinetics at both standard and double doses, with preharvest intervals being 9, 60, and 26 days at standard dose. At double dose, the preharvest intervals extended to 20.5, 100, and 60 days, respectively.

A targeted metabolomic protocol for short-chain fatty acids and branched-chain amino acids

PubMed Central

Zheng, Xiaojiao; Qiu, Yunping; Zhong, Wei; Baxter, Sarah; Su, Mingming; Li, Qiong; Xie, Guoxiang; Ore, Brandon M.; Qiao, Shanlei; Spencer, Melanie D.; Zeisel, Steven H.; Zhou, Zhanxiang; Zhao, Aihua; Jia, Wei

2013-01-01

Research in obesity and metabolic disorders that involve intestinal microbiota demands reliable methods for the precise measurement of the short-chain fatty acids (SCFAs) and branched-chain amino acids (BCAAs) concentration. Here, we report a rapid method of simultaneously determining SCFAs and BCAAs in biological samples using propyl chloroformate (PCF) derivatization followed by gas chromatography mass spectrometry (GC-MS) analysis. A one-step derivatization using 100 µL of PCF in a reaction system of water, propanol, and pyridine (v/v/v = 8:3:2) at pH 8 provided the optimal derivatization efficiency. The best extraction efficiency of the derivatized products was achieved by a two-step extraction with hexane. The method exhibited good derivatization efficiency and recovery for a wide range of concentrations with a low limit of detection for each compound. The relative standard deviations (RSDs) of all targeted compounds showed good intra- and inter-day (within 7 days) precision (< 10%), and good stability (< 20%) within 4 days at room temperature (23–25 °C), or 7 days when stored at −20 °C. We applied our method to measure SCFA and BCAA levels in fecal samples from rats administrated with different diet. Both univariate and multivariate statistics analysis of the concentrations of these target metabolites could differentiate three groups with ethanol intervention and different oils in diet. This method was also successfully employed to determine SCFA and BCAA in the feces, plasma and urine from normal humans, providing important baseline information of the concentrations of these metabolites. This novel metabolic profile study has great potential for translational research. PMID:23997757

Ammonium hydroxide enhancing electrospray response and boosting sensitivity of bisphenol A and its analogs.

PubMed

Tan, Dongqin; Jin, Jing; Wang, Longxing; Zhao, Xueqin; Guo, Cuicui; Sun, Xiaoli; Dhanjai; Lu, Xianbo; Chen, Jiping

2018-05-15

As one of the most important analytical techniques for accurate quantification of bisphenol compounds, liquid chromatography coupled to online electrospray ionization (ESI) tandem mass spectrometry exhibits relative weak ESI response in negative mode, which greatly reduces their sensitivity and limits their detection at trace levels, especially in complex samples such as blood. Based on the facilitated deprotonation of bisphenol molecule under alkaline condition, post-column injection of ammonium hydroxide (NH 3 ·H 2 O) to mass spectrometer was explored to enhance the ionization efficiency of BPA and its eight analogs and improve their analytical sensitivity. Parameters effecting response intensity and stability were investigated, including mass concentration and flow rate of NH 3 ·H 2 O. Under the optimal conditions with the addition of 2% (w/w) of NH 3 ·H 2 O at 4 μL min -1 , the instrument detection limits for bisphenol compounds were greatly lowered to 0.001-0.04 ng mL -1 , which were 2-28.6 times lower than the result obtained without injecting NH 3 ·H 2 O, except TBBPA (0.03 ng mL -1 in either case). The relative standard deviations (RSDs) for instrument repeatability of BPA and its analogs at three different concentration levels were in a range of 1.2-20%. Furthermore, a decreased matrix effects (90-111%) for bisphenols (except TBBPA) analysis in serum extracts were found compared with the result obtained without NH 3 ·H 2 O injection (43-111%). The results demonstrated that the improved instrumental method coupled with suitable pretreatment techniques is more feasible to analyze bisphenol compounds in complex bio-samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Multiresidue determination of chlorophenoxy acid herbicides in human urine samples by use of solid-phase extraction and capillary LC-UV detection.

PubMed

Rosales-Conrado, N; León-González, M E; Pérez-Arribas, L V; Polo-Díez, L M

2008-01-01

Chlorophenoxy acid herbicides are intensively applied to get rid of unwanted plants because of their low cost and selectivity. Due to their toxicity, which depends on their chemical form, the European Community has established legal directives to restrict their use and to control their maximum residue levels in several matrices. Determination of chlorophenoxy acids-2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2-(2,4-dichlorophenoxy)propanoic acid (2,4-DP), 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP), 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB) and 2-(2,4,5-trichlorophenoxy)propanoic acid (2,4,5-TP) in spiked human urine samples has been carried out by capillary LC, after solid-phase extraction on a column packed with silica C18 restricted-access material. Chromatographic analysis was performed in gradient-elution mode at 25 degrees C, with injection of 20 microL low-organic-solvent composition herbicide solutions for focusing purposes on the head of the capillary column, and diode array detection at 232 nm. Urine samples collected during 24 h from healthy and unexposed volunteers were spiked in the concentration range 25-150 microg L(-1); recoveries obtained were between 66 and 100% (n = 6 for each spiked level) and RSDs (relative standard deviations) were between 1 and 5%. Detection limits in the urine samples from volunteers were between 3.5 and 6.0 microg L(-1). The developed methodology has allowed the clean-up and preconcentration of low volumes of untreated human urine without previous treatment, showing the effectiveness of the employed SPE sorbent for extracting the target analytes and ultimately resulting in the reduction of the sample-preparation time.

β-CD/ATP composite materials for use in dispersive solid-phase extraction to measure (fluoro)quinolone antibiotics in honey samples.

PubMed

Cui, Xiangqian; Zhang, Panjie; Yang, Xiaoling; Yang, Miyi; Zhou, Wenfeng; Zhang, Sanbin; Gao, Haixiang; Lu, Runhua

2015-06-09

A novel sorbent (β-CD/ATP composite) for dispersive solid-phase extraction (d-SPE) prepared by bonding β-cyclodextrin to modified attapulgite via silane coupling was used to determine the concentrations of four (fluoro)quinolones (Qs) in honey samples. The subsequent quantification of the Qs (ciprofloxacin, norfloxacin, ofloxacin, and gatifloxacin) was accomplished using high-performance liquid chromatography (HPLC) with ultraviolet detection after the d-SPE procedure. Parameters that may influence the extraction efficiency, such as type and volume of the eluent, type and amount of the sorbent, times of the vortex and sonication process, and pH of the sample, were investigated using batch and column procedures. The optimal experimental conditions (5 mL sample at pH 3, 4 mg of β-CD/ATP composite as the sorbent, 200 μL of 40% ammonia in methanol as the eluent, with vortex time 60s and sonication time 6 min, and no addition of salt) were obtained from this statistical evaluation. The limits of detection (LODs) were determined to the range from 0.30 to 3.95 μg L(-1). Good recoveries (83.6-88.6%) were obtained under the optimum conditions, and the relative standard deviations (RSDs), which are used to indicate reproducibility, were less than 7.4%. The method was validated with three real honey samples, and the results demonstrated that β-CD/ATP composite possessed a high adsorption capacity for Qs. Although the LODs were slightly higher than expected, this study confirmed the possibility of using cyclodextrin grafted palygorskite in analytical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

A sensitive and efficient method for routine pesticide multiresidue analysis in bee pollen samples using gas and liquid chromatography coupled to tandem mass spectrometry.

PubMed

Vázquez, P Parrilla; Lozano, A; Uclés, S; Ramos, M M Gómez; Fernández-Alba, A R

2015-12-24

Several clean-up methods were evaluated for 253 pesticides in pollen samples concentrating on efficient clean-up and the highest number of pesticides satisfying the recovery and precision criteria. These were: (a) modified QuEChERS using dSPE with PSA+C18; (b) freeze-out prior to QuEChERS using dSPE with PSA+C18; (c) freeze-out prior to QuEChERS using dSPE with PSA+C18+Z-Sep; and (d) freeze-out followed by QuEChERS using dSPE with PSA+C18 and SPE with Z-Sep. Determinations were made using LC-MS/MS and GC-MS/MS. The modified QuEChERS protocol applying a freeze-out followed by dSPE with PSA+C18 and SPE clean-up with Z-Sep was selected because it provided the highest number of pesticides with mean recoveries in the 70-120% range, as well as relative standard deviations (RSDs) typically below 20% (12.2% on average) and ensured much better removal of co-extracted matrix compounds of paramount importance in routine analysis. Limits of quantification at levels as low as 5μgkg(-1) were obtained for the majority of the pesticides. The proposed methodology was applied to the analysis of 41 pollen bee samples from different areas in Spain. Pesticides considered potentially toxic to bees (DL50<2μg/bee) were detected in some samples with concentrations up to 72.7μgkg(-1), which could negatively affect honeybee health. Copyright © 2015 Elsevier B.V. All rights reserved.

[Determination of gossypol in edible vegetable oil with high performance liquid chromatography-tandem mass spectrometry].

PubMed

Zhang, Wenhua; Huang, Chaoqun; Xie, Wen; Shen, Li

2014-06-01

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of gossypol in edible vegetable oil. The sample was extracted with ethyl alcohol by vortex-excited oscillation. The extract was cleaned up by 0.22 microm filter membrane and centrifuged for 5 min at 4 000 r/min after standing in a fridge at 4 degrees C for 30 min. The compound was separated on a C18 column (100 mm x 2.1 mm, 3.5 microm) with acetonitrile and 1% (v/v) formic acid aqueous solution as mobile phase. The detection of gossypol was carried out by LC-MS/MS with positive electrospray ionization under multiple reaction monitoring (MRM) mode using external standard method. The limits of quantification (S/N > 10) of gossypol in edible vegetable oil was 1 mg/kg. The recoveries were from 87.4% to 100% at the spiked levels of 1, 2, 200 mg/kg of gossypol in edible vegetable oil with the relative standard deviations (RSDs) between 3.9% and 12.2%. The method, with high sensitivity, good precision and high recovery, was suitable for the confirmation and quantification of gossypol residue in edible vegetable oil.

[Determination of alkylphenol and alkylphenolpolyethoxylates in brine by solid phase extraction and high performance liquid chromatography-mass spectrometry].

PubMed

Wang, Jincheng; Xiong, Li; Zhang, Haijun; Chen, Jiping

2011-12-01

A simple method based on solid phase extraction (SPE) coupled with high performance liquid chromatography-mass spectrometry (HPLC-MS) was developed for the determination of octylphenol (OP), nonylphenol (NP), octylphenol ethoxylates (OPEOs) and nonylphenol ethoxylates (NPEOs) in brine. The extraction and cleanup of brine samples were performed on C18 solid-phase extraction cartridges. The complete separation among OP, NP, OPEOs and NPEOs was achieved on a Hypersil GOLD analytical column with methanol-water as the mobile phase. The determination was achieved using HPLC-MS with electrospray ionization (ESI) in selected ion monitoring mode. The results showed that the average recoveries of target compounds were 59.6% - 104.4% and the corresponding relative standard deviations (RSDs, n = 3) were 1.0% - 13.5%. The instrumental limits of detection for the compounds were 0.08 - 3 microg/L. This method was applied to the analysis of the samples of seawater near Dalian coast. The results showed that both NP and NPEOs were detected in all samples and their concentrations in seaport and oil port were much higher than those in other sampling sites.

An optimized high-performance liquid chromatography (HPLC) method for benzoylmesaconine determination in Radix Aconiti Lateralis Preparata (Fuzi, aconite roots) and its products

PubMed Central

Xie, Ying; Zhou, Hua; Wong, Yuen Fan; Liu, Zhongqiu; Xu, Hongxi; Jiang, Zhihong; Liu, Liang

2008-01-01

Background Benzoylmesaconine (BMA) is the main Aconitum alkaloid in Radix Aconiti Lateralis Preparata (Fuzi, aconite roots) with potent pharmacological activities, such as analgesia and anti-inflammation. The present study developed a simple and reliable method using BMA as a marker compound for the quality control of processed aconite roots and their products. Methods After extraction, a high-performance liquid chromatography (HPLC) determination of BMA was conducted on a RP-C18 column by gradient elution with acetonitrile and aqueous phase, containing 0.1% phosphoric acid adjusted with triethylamine to pH 3.0. Results A distinct peak profile was obtained and separation of BMA was achieved. Method validation showed that the relative standard deviations (RSDs) of the precision of BMA in all intra-day and inter-day assays were less than 1.36%, and that the average recovery rate was 96.95%. Quantitative analysis of BMA showed that the content of BMA varied significantly in processed aconite roots and their products. Conclusion This HPLC method using BMA as a marker compound is applicable to the quality control of processed aconite roots and their products. PMID:18513409

Ultratrace Determination of Cr(VI) and Pb(II) by Microsample Injection System Flame Atomic Spectroscopy in Drinking Water and Treated and Untreated Industrial Effluents

PubMed Central

Baig, Jameel Ahmed; Kazi, Tasneem Gul; Elci, Latif; Afridi, Hassan Imran; Khan, Muhammad Irfan; Naseer, Hafiz Muhammad

2013-01-01

Simple and robust analytical procedures were developed for hexavalent chromium (Cr(VI)) and lead (Pb(II)) by dispersive liquid-liquid microextraction (DLLME) using microsample injection system coupled with flame atomic absorption spectrophotometry (MIS-FAAS). For the current study, ammonium pyrrolidine dithiocarbamate (APDC), carbon tetrachloride, and ethanol were used as chelating agent, extraction solvent, and disperser solvent, respectively. The effective variables of developed method have been optimized and studied in detail. The limit of detection of Cr(VI) and Pb(II) were 0.037 and 0.054 µg/L, respectively. The enrichment factors in both cases were 400 with 40 mL of initial volumes. The relative standard deviations (RSDs, n = 6) were <4%. The applicability and the accuracy of DLLME were estimated by the analysis of Cr(VI) and Pb(II) in industrial effluent wastewater by standard addition method (recoveries >96%). The proposed method was successfully applied to the determination of Cr(VI) and Pb(II) at ultratrace levels in natural drinking water and industrial effluents wastewater of Denizli. Moreover, the proposed method was compared with the literature reported method. PMID:24163779

Capillary electrochromatographic separation of peptides using a macrocyclic polyamine for molecular recognition.

PubMed

Chen, Tse-Hsien; Misra, Tarun Kumar; Liu, Chuen-Ying

2008-04-01

A macrocyclic polyamine, 1,5,9,13,17,21,25,29-octaazacyclodotriacontane ([32]ane-N(8)), in the bonded phase was employed as a molecular receptor for CEC separation of oligopeptides. Parameters affecting the performance of the separations were considered. Baseline separation for the mixture of angiotensin I, angiotensin II, [Sar(1), Thr(8)]-angiotensin II, beta-casomorphin bovine, beta-casomorphin human, oxytocin acetate, tocinoic acid, vasopressin, and FMRF amide could be achieved using phosphate buffer (30 mM, pH 7) as the mobile phase. Column efficiency with average theoretical plate numbers of 69 000 plates/m and RSDs of <1% (n = 6) was achieved. [Met(5)]-enkephalin and [Leu(5)]-enkephalin, which have identical pI values and similar masses could be completely separated using acetate buffer (30 mM) with pH gradient (pH 3 inlet side and pH 4 outlet side). The results suggest that the mechanism for the peptide separation was mediated by a combination of electrophoretic migration and chromatographic retention involving anion coordination and anion exchange. After long-term use, the deviation of the EOF of the column after more than 600 injections was still within 6.0% of that for a freshly prepared column.

Reversed phase HPLC for strontium ranelate: Method development and validation applying experimental design.

PubMed

Kovács, Béla; Kántor, Lajos Kristóf; Croitoru, Mircea Dumitru; Kelemen, Éva Katalin; Obreja, Mona; Nagy, Előd Ernő; Székely-Szentmiklósi, Blanka; Gyéresi, Árpád

2018-06-01

A reverse-phase HPLC (RP-HPLC) method was developed for strontium ranelate using a full factorial, screening experimental design. The analytical procedure was validated according to international guidelines for linearity, selectivity, sensitivity, accuracy and precision. A separate experimental design was used to demonstrate the robustness of the method. Strontium ranelate was eluted at 4.4 minutes and showed no interference with the excipients used in the formulation, at 321 nm. The method is linear in the range of 20-320 μg mL-1 (R2 = 0.99998). Recovery, tested in the range of 40-120 μg mL-1, was found to be 96.1-102.1 %. Intra-day and intermediate precision RSDs ranged from 1.0-1.4 and 1.2-1.4 %, resp. The limit of detection and limit of quantitation were 0.06 and 0.20 μg mL-1, resp. The proposed technique is fast, cost-effective, reliable and reproducible, and is proposed for the routine analysis of strontium ranelate.

Supercritical fluid extraction of 13-cis retinoic acid and its photoisomers from selected pharmaceutical dosage forms.

PubMed

Simmons, B R; Chukwumerije, O; Stewart, J T

1997-11-01

13-Cis retinoic acid (Accutane) was extracted from a cream, gel, capsule and beadlet dosage from using supercritical carbon dioxide modified with 5% methanol as the mobile phase. The pump pressure and the extraction chamber and restrictor temperature were experimentally optimized at 325 atm and 45 degrees C, respectively. A 2.5-min static and 5-min dynamic extraction time were used. The supercritical fluid extraction (SFE) eluent was trapped in methanol, injected into the high-performance liquid chromatographic (HPLC) system, and quantitated by ultraviolet detection at 360 nm. Application of the SFE method to spiked placebo dosage forms gave 13-cis retinoic acid recoveries of 98.8, 98.9, 98.8 and 100% for the cream, gel, capsule and beadlet, respectively, with R.S.D.s in the range 0.6-0.9% (n = 4). Inter-day percent error and precision of the extraction were 1.1-2.0 and 0.2-2.4% (n = 3), respectively, and intra-day percent error and precision were 1.0-3.0 and 0.3-2.1% (n = 8), respectively. Percent error and precision data for spiked celite samples in the 0.05-1.0 microgram ml-1 range were 0.59-4.75 and 1.8-2.1% (n = 3), respectively. The extraction method was applied to commercial 13-cis retinoic acid dosage forms and the results compared to unextracted samples. Linear regression analysis of concentration versus peak height gave a correlation coefficient of 0.9991 with a slope of 7.468 and a y-intercept of 0.1923. The percent error and precision data were 1.3-5.3 and 0.2-1.5% (n = 4), respectively. The photoisomers of 13-cis retinoic acid were also extracted with the method and recoveries of 90.4-92.4% with R.S.D.s of 1.5-3.4% were obtained (n = 4).

One-step green synthesis of β-cyclodextrin/iron oxide-reduced graphene oxide nanocomposite with high supramolecular recognition capability: Application for vortex-assisted magnetic solid phase extraction of organochlorine pesticides residue from honey samples.

PubMed

Mahpishanian, Shokouh; Sereshti, Hassan

2017-02-17

In this research, β-cyclodextrin/iron oxide reduced graphene oxide hybrid nanostructure (β-CD/MRGO) with high water dispersability, excellent magnetic responsivity and molecular selectivity was prepared via a facile one step green strategy. The obtained nanomaterial was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and vibrating sample magnetometry (VSM), which confirmed the modification of GO with β-CD and magnetic nanoparticles. The formation mechanism of β-CD/MRGO was also discussed. The prepared magnetic nanocomposite was then applied as adsorbent in the vortex-assisted magnetic solid phase extraction (MSPE) of 16 organochlorine pesticides (OCPs) from honey samples prior to gas chromatography-electron capture detection (GC-ECD) analysis. Optimum extraction conditions have been assessed with respect to vortex time, sample pH, adsorbent amount, and salt concentration as well as desorption conditions (type and volume of desorption solvent and desorption time). A good level of linearity (2-10,000ngkg -1 ) with satisfactory determination coefficients (R 2 >0.9966) and suitable precision (%RSDs less than 7.8) was obtained for OCPs under the optimal conditions. The limits of detection and quantification of the method were obtained in the sub-parts per trillion (ppt) to parts per trillion range (LOD: 0.52-3.21ngkg -1 ; LOQ: 1.73-10.72ngkg -1 ) based on 3 and 10 signal to noise ratios, respectively. The MSPE method was successfully applied to analysis of OCPs in honey samples with recoveries in the range of 78.8% to 116.2% and RSDs (n=3) below 8.1%. The results demonstrated that β-CD/MRGO could exhibit good supramolecular recognition, enrichment capability and high extraction recoveries toward OCPs. Copyright © 2017 Elsevier B.V. All rights reserved.

[Determination of five microcystins in drinking water by HPLC/MS/MS].

PubMed

Liu, Honghe; Mao, Lisha; Zhu, Zhou; Liu, Guihua; Chen, Yuhua

2012-09-01

A high performance liquid chromatography-tandem mass spectrometric method was established for determination of five microcystins( MC-LR,MC-LW,MC-RR, MC-LF, MC-YR)in drinking water and source water. The five microcystins in water was cleaned by 0.22 microm millipore filter, then detected by high performance liquid chromatography-tandem mass spectrometry. Identification was achieved by electrospray ionization (ESI) in positive mode using multiple reaction monitoring. The calibration curves of five microcystins showed good linearity in the range of 0.5-50 microg/L with correlation coefficient in the range of 0.9994 -1.0000. The detection limit of the method was from 0.06 microg/L to 0.08 microg/L, the recoveries of two spiking levels ranged from 91.2% to 102%, and RSDs of range from 2.11% to 3.26% were obtained. The method for determination of five microcystins in drinking water and source water by HPLC-MS/MS was of operation convenience, less interference from impurities and good accuracy, which could meet the requirements of national health standard method for the determination of microcystins in drinking water.

Simultaneous quantification and identification of flavonoids, lignans, coumarin and amides in leaves of Zanthoxylum armatum using UPLC-DAD-ESI-QTOF-MS/MS.

PubMed

Bhatt, Vinod; Sharma, Sushila; Kumar, Neeraj; Sharma, Upendra; Singh, Bikram

2017-01-05

The current study presents isolation and characterization of twelve compounds including catechin (1), isovitexin (2), hesperidin (3), psoralin (4), eudesmin (5), kobusin (6), fargesin (7), sesamin (8), asarinin (9), planispine-A (10), α-sanshool (11) and vitexin (12), from the leaves of Zanthoxylum armatum. Further, two rapid and simple ultra performance liquid chromatography-diode array detection (UPLC-DAD) methods were developed for the simultaneous quantitative determination of isolated compounds from Z. armatum leaves. These analytical methods were validated for linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). The LOD and LOQ were in the range of 0.06-0.21μg/mL and 0.19-0.69μg/mL, respectively. The validated method was linear (R 2 ≥0.9906), precise in terms of peak area (intra-day RSDs <3.8% and inter-day RSDs <2.7%), and accurate (109.6-92.5%). This is the first report on the isolation and quantification of 1, 2, 4 and 12 in Z. armatum and 3 in Zanthoxylum genus. The methods: were successfully applied to assess the quality of samples collected from different locations of Himachal Pradesh during summer and winter season. The results demonstrated that flavonoids and furofuran lignans were the major constituents in Z. armatum leaves. The developed methods: were further applied for tandem electrospray ionization-mass spectrometry (UPLC-DAD-ESI-MS/MS) and total eighteen compounds were identified including phenolic acid, flavonoids, furofuran lignans, coumarin and isobutyl amides. Copyright © 2016 Elsevier B.V. All rights reserved.

Use of absorbent materials in on-line coupled reversed-phase liquid chromatography-gas chromatography via the through oven transfer adsorption desorption interface.

PubMed

Flores, Gema; Díaz-Plaza, Eva María; Cortés, Jose Manuel; Villén, Jesús; Herraiz, Marta

2008-11-21

The use of absorbents as retaining materials in the through oven transfer adsorption desorption interface (TOTAD) of an on-line coupled reversed-phase liquid chromatography-gas chromatography system (RPLC-GC) is proposed for the first time. A comparative study of an adsorbent (Tenax TA) and two absorbents, namely polydimethylsiloxane and poly(50% phenyl/50% methylsiloxane) is performed to establish the best experimental conditions for the automated and simultaneous determination of 15 organophosphorus and organochlorine pesticide residues in olive oil. The proposed method provides satisfactory repeatability (RSDs lower, in general, than 8.5%) and sensitivity (limits of detection ranging from 0.6 to 81.9 microg/L) for the investigated compounds.

An Extract of Artemisia dracunculus L. Promotes Psychological Resilience in a Mouse Model of Depression

PubMed Central

Wang, Jun; Fernández, Adelaida Esteban; Tiano, Simoni; Huang, Jing; Floyd, Elizabeth; Poulev, Alexander

2018-01-01

Stress-induced peripheral inflammation contributes to depression-like behaviors in both human and experimental models. PMI 5011, a botanical extract of Artemisia dracunculus L., was previously shown to have multiple bioactivities, including anti-inflammatory activity. In this work, using a repeated social defeat stress (RSDS) model of depression, we demonstrate that oral administration of the botanical extract PMI 5011 promotes resilience to RSDS-mediated depression-like phenotypes. We also show that the behavioral improvements are associated with attenuation of stress-mediated induction of inflammatory cytokines in the periphery and alteration of synaptic plasticity in the nucleus accumbens (NAc). Our studies provide experimental evidence that botanical extracts such as PMI 5011, which target pathological mechanisms (i.e., peripheral inflammation) not addressed by currently available antidepressants, could be further developed as novel therapeutics for the treatment of stress disorders and anxiety in humans. PMID:29861834

Enantioselectivity of debrisoquine 4-hydroxylation in Brazilian Caucasian hypertensive patients phenotyped as extensive metabolizers.

PubMed

Cerqueira, P M; Mateus, F H; Cesarino, E J; Bonato, P S; Lanchote, V L

2000-12-01

Debrisoquine (D), an antihypertensive drug metabolized to 4-hydroxydebrisoquine (4-OHD) by CYP2D6, is commonly used as an in vivo probe of CYP2D6 activity and can be used to phenotype individuals as either extensive (EMs) or poor metabolizers (PMs) of such drugs as beta-adrenergic blockers, tricyclic antidepressants, and class 1C antiarrhythmics. This report describes reversed-phase HPLC systems by which D and 4-OHD or S-(+) and R-(-)-4-OHD in urine are more selectively quantified without the need for derivatization techniques. We also studied the urinary excretion of R-(-)- and S-(+)-4-hydroxydebrisoquine in EM hypertensive patients in order to determine weather 4-OHD formation exhibits enantioselectivity. Twelve patients with mild to severe essential hypertension were admitted to the study. They received a single tablet of Declinax containing 10 mg debrisoquine sulfate. All the urine excreted during the following 8 h was collected. The debrisoquine metabolic ratio (DMR) was calculated as % of dose excreted as D/% of dose excreted as 4-OHD and the debrisoquine recovery ratio (DRR) was calculated as % of dose excreted as 4-OHD/% of dose excreted as D+4-OHD. Debrisoquine and its metabolite were determined in urine by HPLC using a reversed-phase Select B LiChrospher column, a mobile phase of 0.25 N acetate buffer, pH 5-acetonitrile (9:1, v/v) and a fluorescence detector. The limit of quantitation was determined to be 25.0 ng/ml for D and 18.75 ng/ml for 4-OHD. Intra- and inter-day relative standard deviations (RSDs) were less than 10%. All hypertensive patients studied showed a DMR of less than 12.6 or a DRR higher than 0.12 and were classified as EMs. Direct enantioselective separation on chiral stationary phase involved resolution of S-(+)-4-OHD and R-(-)-4-OHD on a Chiralcel OD-R column with a mobile phase of 0.125 N sodium perchlorate, pH 5-acetonitrile-methanol (85:12:3, v/v/v). The quantitation limit of each enantiomer was 3.75 ng/ml of urine. Intra- and inter-day RSDs were less than 10% for each enantiomer. A high degree of enantioselectivity in the 4-hydroxylation of D favouring the S-(+) enantiomer was observed, resulting in R-(-)-4-OHD not detected in the urine of the EM hypertensive patients studied.

[Qualitative and quantitative analysis of amygdalin and its metabolite prunasin in plasma by ultra-high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry and ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry].

PubMed

Gao, Meng; Wang, Yuesheng; Wei, Huizhen; Ouyang, Hui; He, Mingzhen; Zeng, Lianqing; Shen, Fengyun; Guo, Qiang; Rao, Yi

2014-06-01

A method was developed for the determination of amygdalin and its metabolite prunasin in rat plasma after intragastric administration of Maxing shigan decoction. The analytes were identified by ultra-high performance liquid chromatography-tandem quadrupole time of flight mass spectrometry and quantitatively determined by ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry. After purified by liquid-liquid extraction, the qualitative analysis of amygdalin and prunasin in the plasma sample was performed on a Shim-pack XR-ODS III HPLC column (75 mm x 2.0 mm, 1.6 microm), using acetonitrile-0.1% (v/v) formic acid aqueous solution. The detection was performed on a Triple TOF 5600 quadrupole time of flight mass spectrometer. The quantitative analysis of amygdalin and prunasin in the plasma sample was performed by separation on an Agilent C18 HPLC column (50 mm x 2.1 mm, 1.7 microm), using acetonitrile-0.1% (v/v) formic acid aqueous solution. The detection was performed on an AB Q-TRAP 4500 triple quadrupole mass spectrometer utilizing electrospray ionization (ESI) interface operated in negative ion mode and multiple-reaction monitoring (MRM) mode. The qualitative analysis results showed that amygdalin and its metabolite prunasin were detected in the plasma sample. The quantitative analysis results showed that the linear range of amygdalin was 1.05-4 200 ng/mL with the correlation coefficient of 0.999 0 and the linear range of prunasin was 1.25-2 490 ng/mL with the correlation coefficient of 0.997 0. The method had a good precision with the relative standard deviations (RSDs) lower than 9.20% and the overall recoveries varied from 82.33% to 95.25%. The limits of detection (LODs) of amygdalin and prunasin were 0.50 ng/mL. With good reproducibility, the method is simple, fast and effective for the qualitative and quantitative analysis of the amygdalin and prunasin in plasma sample of rats which were administered by Maxing shigan decoction.

A quantitative, selective and fast ultra-high performance liquid chromatography tandem mass spectrometry method for the simultaneous analysis of 33 basic drugs in hair (amphetamines, cocaine, opiates, opioids and metabolites).

PubMed

Fernández, María Del Mar Ramírez; Di Fazio, Vincent; Wille, Sarah M R; Kummer, Natalie; Samyn, Nele

2014-08-15

Forensic testing for drugs of abuse in hair has become a useful diagnostic tool in determining chronic drug use as well as examining long-term drug history thorough segmental analysis. However, sensitive and specific analytical methods are needed. A simple, rapid and highly sensitive and specific method for the extraction and quantification of 33 opioids, opiates, cocaine, and amphetamines is presented. The method was fully validated according to international guidelines. Twenty milligrams of hair sample was pulverized and then incubated in the same disposable tube with methanol (under sonication at 45°C) during 4h. After centrifugation the supernatant was evaporated up to about 100 μL and a solid phase extraction (SPE) followed by separation and quantification using ultra performance liquid chromatography-tandem mass spectrometry (UHLC-MS/MS) were carried out. Chromatographic separation was achieved using a BEH phenyl column eluted with 0.1% formic acid: methanol (0.1% formic acid). Selectivity of the method was achieved by a combination of retention time, and two precursor-product ion transitions. Good intra-assay and inter-assay precision (relative standard deviations (RSDs) were observed (<15%) for most of the compounds. The lower limit of quantification was fixed at the lowest calibrator in the linearity experiments and it ranged from 0.006 to 0.063 ng/mg. No instability was observed in processed samples. Extraction efficiency varied from 37 to 107% (except for EDDP with a recovery of 5%) and matrix effects ranged from 52 to 160%, and for most of the compounds it was compensated by the internal standard (IS). The method was subsequently applied to authentic hair samples obtained from forensic and toxicology cases and to proficiency test (obtaining z-scores lower than 1 for most of the compounds). The validation and actual sample analysis results show that this method is rugged, precise, accurate, and well-suited for routine hair analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous determination of a variety of endocrine disrupting compounds in carrot, lettuce and amended soil by means of focused ultrasonic solid-liquid extraction and dispersive solid-phase extraction as simplified clean-up strategy.

PubMed

Mijangos, L; Bizkarguenaga, E; Prieto, A; Fernández, L A; Zuloaga, O

2015-04-10

The present study is focused on the development of an analytical method based on focused ultrasonic solid-liquid extraction (FUSLE) followed by dispersive solid-phase extraction (dSPE) clean-up and liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS) optimised for the simultaneous analysis of certain endocrine disrupting compounds (EDCs), including alkylphenols (APs), bisphenol A (BPA), triclosan (TCS) and several hormones and sterols in vegetables (lettuce and carrot) and amended soil samples. Different variables affecting the chromatographic separation, the electrospray ionisation and mass spectrometric detection were optimised in order to improve the sensitivity of the separation and detection steps. Under the optimised extraction conditions (sonication of 5min at 33% of power with pulse times on of 0.8s and pulse times off of 0.2s in 10mL of n-hexane:acetone (30:70, v:v) mixture using an ice bath), different dSPE clean-up sorbents, such as Florisil, Envi-Carb, primary-secondary amine bonded silica (PSA) and C18, or combinations of them were evaluated for FUSLE extracts before LC-MS/MS. Apparent recoveries and precision in terms of relative standard deviation (RSDs %) of the method were determined at two different fortification levels (according to the matrix and the analyte) and values in the 70-130% and 2-27% ranges, respectively, were obtained for most of the target analytes and matrices. Matrix-matched calibration approach and the use of labelled standards as surrogates were needed for the properly quantification of most analytes and matrices. Method detection limits (MDLs), estimated with fortified samples, in the ranges of 0.1-100ng/g for carrot, 0.2-152ng/g for lettuce and 0.9-31ng/g for amended soil were obtained. The developed methodology was applied to the analysis of 11 EDCs in both real vegetable bought in a local market and in compost (from a local wastewater treatment plant, WWTP) amended soil samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Fingerprint analysis of Hibiscus mutabilis L. leaves based on ultra performance liquid chromatography with photodiode array detector combined with similarity analysis and hierarchical clustering analysis methods

PubMed Central

Liang, Xianrui; Ma, Meiling; Su, Weike

2013-01-01

Background: A method for chemical fingerprint analysis of Hibiscus mutabilis L. leaves was developed based on ultra performance liquid chromatography with photodiode array detector (UPLC-PAD) combined with similarity analysis (SA) and hierarchical clustering analysis (HCA). Materials and Methods: 10 batches of Hibiscus mutabilis L. leaves samples were collected from different regions of China. UPLC-PAD was employed to collect chemical fingerprints of Hibiscus mutabilis L. leaves. Results: The relative standard deviations (RSDs) of the relative retention times (RRT) and relative peak areas (RPA) of 10 characteristic peaks (one of them was identified as rutin) in precision, repeatability and stability test were less than 3%, and the method of fingerprint analysis was validated to be suitable for the Hibiscus mutabilis L. leaves. Conclusions: The chromatographic fingerprints showed abundant diversity of chemical constituents qualitatively in the 10 batches of Hibiscus mutabilis L. leaves samples from different locations by similarity analysis on basis of calculating the correlation coefficients between each two fingerprints. Moreover, the HCA method clustered the samples into four classes, and the HCA dendrogram showed the close or distant relations among the 10 samples, which was consistent to the SA result to some extent. PMID:23930008

[Determination of formaldehyde and acetaldehyde in packaging paper by dansylhydrazine derivatization-high performance liquid chromatography-fluorescence detection].

PubMed

Gong, Shuguo; Liang, Yong; Tang, Liyun; Huang, Ping; Dai, Yunhui

2017-07-08

A high performance liquid chromatography with fluorescence detection (HPLC-FLD) method was developed for the simultaneous determination of formaldehyde and acetaldehyde in packaging paper by dansylhydrazine (DNSH) derivatization. The samples were extracted by derivatization reagent for 30 min, and derived for 24 h. After purifying treatment with a PSA/C18 cartridge, a Diamonsil ® C18 column (150 mm×4.6 mm, 5 μ m) was used as stationary phase for separation, the mixtures of acetic acid aqueous solution (pH 2.55)-acetonitrile were used as mobile phases by gradient elution, and the excitation and emission wavelengths were 330 nm and 484 nm, respectively. The results showed that the recoveries of formaldehyde and acetaldehyde spiked in the samples were 81.64%-106.78%, and the relative standard deviations (RSDs) were 2.02%-5.53% ( n =5). The limits of detection of formaldehyde and acetaldehyde were 19.2 μ g/kg and 20.7 μ g/kg, respectively. The limits of quantification of formaldehyde and acetaldehyde were 63.9 μ g/kg and 69.1 μ g/kg, respectively. The method is simple, sensitive and reproducible. It provides a basic approach for the determination of trace formaldehyde and acetaldehyde.

[Preparation and applications of a supported liquid-liquid extraction column with a composite diatomite material].

PubMed

Bao, Jianmin; Ma, Zhishuang; Sun, Ying; Wang, Yongzun; Li, Youxin

2012-08-01

A rapid and special supported liquid-liquid extraction (SLE) column was developed with a composite diatomite material. The SLE column was evaluated by high performance liquid chromatography (HPLC) with acidic, neutral and alkaline compounds dissolved in water. Furthermore, some real complex samples were also analyzed by HPLC with the SLE method. The recoveries of benzoic acid (acidic), p-nitroaniline (alkaline) and 4-hydroxy-benzoic methyl ester (neutral) treated by the SLE column were 90.6%, 98.1% and 97.7%. However, the recoveries of the three compounds treated by traditional liquid-liquid extraction (LLE) method were 71.9%, 81.9% and 83.9%. The results showed that the SLE technique had higher recoveries than the traditional LLE method. The spiked recoveries of the complex samples, such as benzoic acid in Sprite and dexamethasone acetate, chlorphenamine maleate, indomethacin in bovine serum, were between 80% and 110% and the relative standard deviations (RSDs) were less than 15%. For biological specimen, the results could be accepted. Meantime, many disadvantages associated with traditional LLE method, such as emulsion formation, didn't occur using SLE column. The SLE column technique is a good sample preparation method with many advantages, such as rapid, simple, robust, easily automated, high recovery and high-throughput, which would be widely used in the future.

Sol-gel polydimethylsiloxane/poly(vinylalcohol)-coated stir bar sorptive extraction of organophosphorus pesticides in honey and their determination by large volume injection GC.

PubMed

Yu, Chunhe; Hu, Bin

2009-01-01

A PDMS/poly(vinylalcohol) (PDMS/PVA) film prepared through a sol-gel process was coated on stir bars for sorptive extraction, followed by liquid desorption and large volume injection-GC-flame photometric detector (LVI-GC-FPD) for the determination of five organophosphorus pesticides (OPPs) (phorate, fenitrothion, malathion, parathion, and quinalphos) in honey. The preparation reproducibility of PDMS/PVA-coated stir bar ranged from 4.3 to 13.4% (n = 4) in one batch, and from 6.0 to 12.6% (n = 4) in batch to batch. And one prepared stir bar can be used for more than 50 times without apparent coating loss. The significant parameters affecting stir bar sorptive extraction (SBSE) were investigated and optimized. The LODs for five OPPs ranged from 0.013 (parathion) to 0.081 microg/L (phorate) with the RSDs ranging from 5.3 to 14.2% (c = 1 microg/L, n = 6). The proposed method was successfully applied to the analysis of five OPPs in honey.

Fast Determination of Yttrium and Rare Earth Elements in Seawater by Inductively Coupled Plasma-Mass Spectrometry after Online Flow Injection Pretreatment.

PubMed

Zhu, Zuhao; Zheng, Airong

2018-02-23

A method for daily monitoring of yttrium and rare earth elements (YREEs) in seawater using a cheap flow injection system online coupled to inductively coupled plasma-mass spectrometry is reported. Toyopearl AF Chelate 650M ® resin permits separation and concentration of YREEs using a simple external calibration. A running cycle consumed 6 mL sample and took 5.3 min, providing a throughput of 11 samples per hour. Linear ranges were up to 200 ng kg -1 except Tm (100 ng kg -1 ). The precision of the method was <6% (RSDs, n = 5), and recoveries ranged from 93% to 106%. Limits of detection (LODs) were in the range 0.002 ng kg -1 (Tm) to 0.078 ng kg -1 (Ce). Good agreement between YREEs concentrations in CASS-4 and SLEW-3 obtained in this work and results from other studies was observed. The proposed method was applied to the determination of YREEs in seawater from the Jiulong River Estuary and the Taiwan Strait.

Simultaneous determination of chlorinated organic compounds from environmental samples using gas chromatography coupled with a micro electron capture detector and micro-plasma atomic emission detector

NASA Astrophysics Data System (ADS)

Quan, Xie; Chen, Shuo; Platzer, Bernhard; Chen, Jingwen; Gfrerer, Marion

2002-01-01

Water and sediment samples were screened simultaneously for the presence of polychlorinated organic compounds using gas chromatography (GC) coupled with an micro electron capture detector (μ-ECD) and a newly developed helium plasma based on a micro-atomic emission detector (μ-AED). The GC column effluent was split 15:85 between two detectors. In this way, two chromatograms, one obtained by μ-ECD and another by μ-AED, were recorded simultaneously. α-, β-hexachlorocyclohexane and p, p'-DDE were detected. RSDs of the monitoring results from the two detection methods were <20% for the three compounds. A detection limit of 8.5 pg and at least 3 orders of magnitude of linear range for μ-AED was observed.

Optimized, Fast-Throughput UHPLC-DAD Based Method for Carotenoid Quantification in Spinach, Serum, Chylomicrons, and Feces.

PubMed

Eriksen, Jane N; Madsen, Pia L; Dragsted, Lars O; Arrigoni, Eva

2017-02-01

An improved UHPLC-DAD-based method was developed and validated for quantification of major carotenoids present in spinach, serum, chylomicrons, and feces. Separation was achieved with gradient elution within 12.5 min for six dietary carotenoids and the internal standard, echinenone. The proposed method provides, for all standard components, resolution > 1.1, linearity covering the target range (R > 0.99), LOQ < 0.035 mg/L, and intraday and interday RSDs < 2 and 10%, respectively. Suitability of the method was tested on biological matrices. Method precision (RSD%) for carotenoid quantification in serum, chylomicrons, and feces was below 10% for intra- and interday analysis, except for lycopene. Method accuracy was consistent with mean recoveries ranging from 78.8 to 96.9% and from 57.2 to 96.9% for all carotenoids, except for lycopene, in serum and feces, respectively. Additionally, an interlaboratory validation study on spinach at two institutions showed no significant differences in lutein or β-carotene content, when evaluated on four occasions.

The use of silica-coated magnetic graphene microspheres as the adsorbent for the extraction of pyrethroid pesticides from orange and lettuce samples followed by GC-MS analysis.

PubMed

Hou, Mengying; Zang, Xiaohuan; Wang, Chun; Wang, Zhi

2013-10-01

Graphene-grafted ferroferric oxide microspheres were used as the adsorbent to extract some pyrethroid pesticides (bifenthrin, λ-cyhalothrin, cyfluthrin, cypermethrin, fenvalerate, and deltamethrin) from orange and lettuce samples prior to their determination by GC-MS. The main variables that could affect the extraction, including the amount of the adsorbent, pH of the sample solution, extraction time, concentration of salt, and desorption conditions, were investigated and optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 0.3-100.0 ng/g for the analytes with the coefficients of determination ranging from 0.9877 to 0.9925. The LODs for the pyrethroids ranged from 0.01 to 0.02 ng/g. The method provided a good repeatability with RSDs < 10.6%. The recoveries for the six pyrethroid pesticides were in the range from 90.0 to 103.7%. The method was applied to the determination of the pesticides in orange and lettuce samples with a satisfactory result. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method for Derivatization and Detection of Chemical Weapons Convention Related Sulfur Chlorides via Electrophilic Addition with 3-Hexyne.

PubMed

Goud, D Raghavender; Pardasani, Deepak; Purohit, Ajay Kumar; Tak, Vijay; Dubey, Devendra Kumar

2015-07-07

Sulfur monochloride (S2Cl2) and sulfur dichloride (SCl2) are important precursors of the extremely toxic chemical warfare agent sulfur mustard and classified, respectively, into schedule 3.B.12 and 3.B.13 of the Chemical Weapons Convention (CWC). Hence, their detection and identification is of vital importance for verification of CWC. These chemicals are difficult to detect directly using chromatographic techniques as they decompose and do not elute. Until now, the use of gas chromatographic approaches to follow the derivatized sulfur chlorides is not reported in the literature. The electrophilic addition reaction of sulfur monochloride and sulfur dichloride toward 3-hexyne was explored for the development of a novel derivatization protocol, and the products were subjected to gas chromatography-mass spectrometric (GC-MS) analysis. Among various unsaturated reagents like alkenes and alkynes, symmetrical alkyne 3-hexyne was optimized to be the suitable derivatizing agent for these analytes. Acetonitrile was found to be the suitable solvent for the derivatization reaction. The sample preparation protocol for the identification of these analytes from hexane spiked with petrol matrix was also optimized. Liquid-liquid extraction followed by derivatization was employed for the identification of these analytes from petrol matrix. Under the established conditions, the detection and quantification limits are 2.6 μg/mL, 8.6 μg/mL for S2Cl2 and 2.3 μg/mL, 7.7 μg/mL for SCl2, respectively, in selected ion monitoring (SIM) mode. The calibration curve had a linear relationship with y = 0.022x - 0.331 and r(2) = 0.992 for the working range of 10 to 500 μg/mL for S2Cl2 and y = 0.007x - 0.064 and r(2) = 0.991 for the working range of 10 to 100 μg/mL for SCl2, respectively. The intraday RSDs were between 4.80 to 6.41%, 2.73 to 6.44% and interday RSDs were between 2.20 to 7.25% and 2.34 to 5.95% for S2Cl2 and SCl2, respectively.

Simultaneous determination of several phytohormones in natural coconut juice by hollow fiber-based liquid-liquid-liquid microextraction-high performance liquid chromatography.

PubMed

Wu, Yunli; Hu, Bin

2009-11-06

A simple, selective, sensitive and inexpensive method of hollow fiber-based liquid-liquid-liquid microextraction (HF-LLLME) combined with high performance liquid chromatography (HPLC)-ultraviolet (UV) detection was developed for the determination of four acidic phytohormones (salicylic acid (SA), indole-3-acetic acid (IAA), (+/-) abscisic acid (ABA) and (+/-) jasmonic acid (JA)) in natural coconut juice. To the best of our knowledge, this is the first report on the use of liquid phase microextraction (LPME) as a sample pretreatment technique for the simultaneous analysis of several phytohormones. Using phenetole to fill the pores of hollow fiber as the organic phase, 0.1molL(-1) NaOH solution in the lumen of hollow fiber as the acceptor phase and 1molL(-1) HCl as the donor phase, a simultaneous preconcentration of four target phytohormones was realized. The acceptor phase was finally withdrawn into the microsyringe and directly injected into HPLC for the separation and quantification of the target phytohormones. The factors affecting the extraction efficiency of four phytohormones by HF-LLLME were optimized with orthogonal design experiment, and the data was analyzed by Statistical Product and Service Solutions (SPSS) software. Under the optimized conditions, the enrichment factors for SA, IAA, ABA and JA were 243, 215, 52 and 48, with the detection limits (S/N=3) of 4.6, 1.3, 0.9ngmL(-1) and 8.8 microg mL(-1), respectively. The relative standard deviations (RSDs, n=7) were 7.9, 4.9, 6.8% at 50ngmL(-1) level for SA, IAA, ABA and 8.4% at 500 microg mL(-1) for JA, respectively. To evaluate the accuracy of the method, the developed method was applied for the simultaneous analysis of several phytohormones in five natural coconut juice samples, and the recoveries for the spiked samples were in the range of 88.3-119.1%.

Speciation analysis of inorganic arsenic by magnetic solid phase extraction on-line with inductively coupled mass spectrometry determination.

PubMed

Montoro Leal, P; Vereda Alonso, E; López Guerrero, M M; Cordero, M T Siles; Cano Pavón, J M; García de Torres, A

2018-07-01

Arsenic, one of the main environmental pollutants and potent natural poison, is a chemical element that is spread throughout the Earth's crust. It is well known that the toxicity of arsenic is highly dependent on its chemical forms. Generally, the inorganic species are more toxic than its organics forms, and As(III) is 60 times more toxic than As(V). In environmental waters, arsenic exists predominantly in two chemical forms: As(III) and As(V). In view of these facts, fast, sensitive, accurate and simple analytical methods for the speciation of inorganic arsenic in environmental waters are required. In this work, a new magnetic solid phase extraction with a hydride generation system was coupled on line with inductively coupled plasma mass spectrometry (MSPE-HG-ICP-MS). The new system was based on the retention of As(III) and As(V) in two knotted reactors filled with (Fe 3 O 4 ) magnetic nanoparticles functionalized with [1,5-bis (2-pyridyl) 3-sulfophenylmethylene] thiocarbonohydrazide (PSTH-MNPs). As(III) and total inorganic As were sequentially eluted in different reduction conditions. The concentration of As(V) was obtained by subtracting As(III) from total As. The system runs in a fully automated way and the method has proved to have a wide linear range and to be precise, sensitive and fast. The detection limits found were 2.7 and 3.2 ng/L for As(III) and total As, respectively; with relative standard deviations (RSDs) of 2.5% and 2.7% and a sample throughput of 14.4 h -1 . In order to validate the developed method, several certified reference samples of environmental waters including sea water, were analyzed and the determined values were in good agreement with the certified values. The proposed method was successfully applied to the speciation analysis of inorganic arsenic in well-water and sea water. Copyright © 2018 Elsevier B.V. All rights reserved.

Comparison of the Conventional and Electroenhanced Direct-Immersion Solid-Phase Microextraction for Sampling of Nicotine in Biological Fluids of the Human Body.

PubMed

Abdolhosseini, Sana; Ghiasvand, Ali Reza; Heidari, Nahid

2018-05-14

A stainless steel fiber was made porous and adhesive by platinization and then coated by nanostructured polypyrrole (PPy), using an appropriate electrophoretic deposition (EPD) method. The morphological surface structure and functional groups of the PPy-coated fiber were studied using SEM (Scanning electron microscope) instrument. The prepared fiber was used for comparison of direct immersion (DI) and electroenhanced direct immersion solid-phase microextraction (EE-DI-SPME) of nicotine in human plasma and urine samples followed by gas chromatography flame ionization detector (GC-FID) determination. The effects of the influential experimental parameters on the efficiency of the DI-SPME and EE-DI-SPME methods, including the pH and ionic strength of the sample solution, applied Direct current (DC) voltage, extraction temperature and time and stirring rate, were optimized. Under the optimal conditions, the calibration curves for the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were linear over the ranges of 0.1⁻10.0 μg mL -1 and 0.001⁻10.0 μg mL -1 , respectively. The relative standard deviations (RSDs, n = 6) were found to be 6.1% and 4.6% for the DI and EE strategies, respectively. The LODs (limit of detection) of the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were found to be 10 and 0.3 ng mL -1 , respectively. The relative recovery values (for the analysis of 1 µg mL -1 nicotine) were found to be 91⁻110% for EE-DI-SPME and 75⁻105% for DI-SPME. The enrichment factors for DI-SPME and EE-DI-SPME sampling were obtained as 38,734 and 50,597, respectively. The results indicated that EE-SPME was more efficient for quantitation of nicotine in biological fluids. The developed procedure was successfully carried out for the extraction and measurement of nicotine in real plasma and urine samples.

Simultaneous determination of traces of pyrethroids, organochlorines and other main plant protection agents in agricultural soils by headspace solid-phase microextraction-gas chromatography.

PubMed

Fernandez-Alvarez, Maria; Llompart, Maria; Lamas, J Pablo; Lores, Marta; Garcia-Jares, Carmen; Cela, Rafael; Dagnac, Thierry

2008-04-25

A solvent-free and simple method based on headspace solid-phase microextraction (HS-SPME) was developed in order to determine simultaneously 36 common pesticides and breakdown products (mostly pyrethroids and organochlorine compounds) in soil. The analysis was carried out by gas chromatography with micro-electron-capture detection (GC-microECD). As far as we know, this is the first study about the SPME of pyrethroid insecticides from soil. Factors such as extraction temperature, matrix modification by addition of water, salt addition (% NaCl) and fiber coating were considered in the optimization of the HS-SPME. To this end, a 3 x 2(3-1) fractional factorial design was performed. The results showed that temperature and fiber coating were the most significant variables affecting extraction efficiency. A suitable sensitivity for all investigated compounds was achieved at 100 degrees C by extracting soil samples wetted with 0.5 mL of ultrapure water (0% NaCl) employing a polyacrylate (PA) coating fiber. Using the recommended extraction conditions with GC-microECD, a linear calibration could be achieved over a range of two orders of magnitude for both groups of analytes. Limits of detection (LODS) at the sub-ng g(-1) level were attained and relative standard deviations (RSDs) were found to be lower than 14% for both groups of pesticides. Matrix effects were investigated by the analysis of different soil samples fortified with the target compounds. The method accuracy was assessed and good recovery values (>70%, in most cases) were obtained. The method was also validated with a certified reference material (RTC-CRM818-050), which was quantified using a standard addition protocol. Finally, the proposed HS-SPME-GC-microECD methodology was further applied to the screening of environmental soil samples for the presence of the target pesticides.

Determination of six microcystins and nodularin in surface and drinking waters by on-line solid phase extraction-ultra high pressure liquid chromatography tandem mass spectrometry.

PubMed

Beltrán, Eduardo; Ibáñez, María; Sancho, Juan Vicente; Hernández, Félix

2012-11-30

Microcystins and nodularin are cyclic peptides hepatotoxins produced by cyanobacterial genera (blue-green algae). Toxic cyanobacterial blooms are a worldwide problem, as reported in several countries, like China, Australia, or the United States. Therefore, it is necessary to develop sensitive and reliable analytical methodology to determine this type of toxins in water at parts per billion levels, or even lower. In this work, the potential of solid-phase extraction coupled on-line to ultra-high-pressure liquid chromatography/electrospray tandem mass spectrometry (SPE-UHPLC-MS/MS) has been investigated for the efficient quantification and confirmation of microcystins LR, RR, YR, LY, LW, LF and nodularin in surface and drinking water samples, at sub-ppb levels. The method developed involves the injection of only 1 mL of water sample into the on-line SPE-UHPLC-MS/MS system and allows the rapid determination of the compounds selected (8 min of chromatographic run), avoiding laborious sample treatment. The method was validated in surface and drinking water by means of recovery experiments at 0.25 and 1 μg L(-1). Average recoveries (n=5) ranged from 71 to 116%, with relative standard deviations (RSDs) lower than 15%. For microcystins LR, RR, YR and nodularin, a third level was also assayed (0.1 μg L(-1)) obtaining satisfactory data too. Limits of detection between 0.002 and 0.0405 μg L(-1) were estimated (0.0005 μg L(-1) for nodularin). The developed method was applied to the analysis of water samples collected in the province of Castellón (Spain). The acquisition of three MS/MS transitions for each compound allowed the unequivocal confirmation of positive samples, which was supported by the accomplishment of ion intensity ratios and retention time when compared with reference standards. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of chlorogenic acids and caffeine in homemade brewed coffee prepared under various conditions.

PubMed

Jeon, Jong-Sup; Kim, Han-Taek; Jeong, Il-Hyung; Hong, Se-Ra; Oh, Moon-Seog; Park, Kwang-Hee; Shim, Jae-Han; Abd El-Aty, A M

2017-10-01

Coffee, a complex mixture of more than 800 volatile compounds, is one of the most valuable commodity in the world, whereas caffeine and chlorogenic acids (CGAs) are the most common compounds. CGAs are mainly composed of caffeoylquinic acids (CQAs), dicaffeoylquinic acids (diCQAs), and feruloylquinic acids (FQAs). The major CGAs in coffee are neochlorogenic acid (3-CQA), cryptochlorogenic acid (4-CQA), and chlorogenic acid (5-CQA). Many studies have shown that it is possible to separate the isomers of FQAs by high-performance liquid chromatography (HPLC). However, some authors have shown that it is not possible to separate 4-feruloylquinic acid (4-FQA) and 5-feruloylquinic acid (5-FQA) by HPLC. Therefore, the present study was designated to investigate the chromatographic problems in the determination of CGAs (seven isomers) and caffeine using HPLC-DAD. The values of determination coefficient (R 2 ) calculated from external-standard calibration curves were >0.998. The recovery rates conducted at 3 spiking levels ranged from 99.4% to 106.5% for the CGAs and from 98.8% to 107.1% for the caffeine. The precision values (expressed as relative standard deviations (RSDs)) were <7% and <3% for intra and interday variability, respectively. The tested procedure proved to be robust. The seven CGAs isomers except 4-FQA and 5-FQA were well distinguished and all gave good peak shapes. We have found that 4-FQA and 5-FQA could not be separated using HPLC. The method was extended to investigate the effects of different brewing conditions such as the roasting degree of green coffee bean, coffee-ground size, and numbers of boiling-water pours, on the concentration of CGAs and caffeine in homemade brewed coffee, using nine green coffee bean samples of different origins. It was reported that medium-roasted, fine-ground coffees brewed using three pours of boiling water were the healthiest coffee with fluent CGAs. Copyright © 2017 Elsevier B.V. All rights reserved.

Enantiomeric separation of seven β-agonists by NACE-Study of chiral selectivity with diacetone-d-mannitol-boric acid complex.

PubMed

Lv, Lili; Wang, Lijuan; Li, Jun; Jiao, Yajun; Gao, Shengnan; Wang, Jiachang; Yan, Hongyuan

2017-10-25

A rapid and effective nonaqueous capillary electrophoresis (NACE)-ultraviolet (UV) method was developed for the enantiomeric separation of seven β-agonists. Diacetone-d-mannitol-boric acid complex was used as a new chiral selector. It was in situ synthesized by the reaction of diacetone-d-mannitol and boric acid in methanol medium containing triethylamine. The effects of diacetone-d-mannitol, boric acid, and triethylamine concentrations on the enantioseparation were carefully investigated. Under the optimized conditions, baseline enantioseparation could be obtained for six of the tested β-agonists within 12min. These results were better than that obtained with d-mannitol-boric acid complex in previous work. 11 B nuclear magnetic resonance ( 11 B NMR) was applied to determine the fraction of boron species and confirm the formation of diacetone-d-mannitol-boric acid complex. Validation of the established NACE method was also carried out according to ICH guidelines. Calibration curves showed good linearity with correlation coefficients (r)≥0.9992 over a certain concentration range for each enantiomer of the tested five β-agonists. The relative standard deviations (RSDs) of intra-day precisions and inter-day precisions of migration times were ≤1.4% (n=6), and ≤6.3% (n=10), respectively. That of peak areas were ≤3.7% (n=6), and ≤5.6% (n=10), respectively. The limits of detection (LODs) and the limits of quantitation (LOQs) based on the signal-to-noise ratios of 3 and 10 were found below 1.25μgmL -1 and 5.00μgmL -1 , respectively. The proposed method was successfully applied to the determination of clenbuterol enantiomers in a multi-component pharmaceutical dosage form called "Ambroxol Hydrochloride and Clenbuterol Hydrochloride Oral Solution". Copyright © 2017 Elsevier B.V. All rights reserved.

Potent method for the simultaneous determination of glutathione and hydrogen peroxide in mitochondrial compartments of apoptotic cells with microchip electrophoresis-laser induced fluorescence.

PubMed

Chen, Zhenzhen; Li, Qingling; Wang, Xu; Wang, Zhiyuan; Zhang, Ruirui; Yin, Miao; Yin, Lingling; Xu, Kehua; Tang, Bo

2010-03-01

The first application of microchip electrophoresis with laser-induced fluorescence (MCE-LIF) detection to simultaneously determine glutathione (GSH) and hydrogen peroxide (H(2)O(2)) in mitochondria was described. Organoselenium probe Rh-Se-2 and bis(p-methylbenzenesulfonate)dichlorofluorescein (FS) synthesized in our laboratory were utilized as fluorescent probes for GSH and H(2)O(2), respectively. Rh-Se-2, which is nonfluorescent, reacts with GSH to produce rhodamine 110 (Rh110) with high quantum yield. Similarly, nonfluorescent FS reacts with H(2)O(2) and produces dichlorofluorescein (DCF) accompanied by drastic fluorescence enhancement. Both probes exhibit good sensitivity toward their respective target molecule determination. Fast, simple, and sensitive determination of GSH and H(2)O(2) was realized within 37 s using a running buffer of 50 mM mannitol, 40 mM HEPES (pH 7.4), and an electric field of 360 V/cm for separation. The linear ranges of the method were 3.3 x 10(-9)-1.0 x 10(-7) M/2.9 x 10(-7)-1.0 x 10(-4) M and 2.7 x 10(-9)-4.0 x 10(-7) M with detection limits (signal-to-noise ratio = 3) of 1.3 nM (0.16 amol) and 1.0 nM (0.12 amol) for GSH and H(2)O(2), respectively. The relative standard deviations (RSDs) of migration time and peak area were less than 1.0% and 4.0%, respectively. The MCE-LIF assay was utilized to investigate the levels of GSH and H(2)O(2) in mitochondria isolated from HepG2 cells and were found to be 2.01 +/- 0.21 mM and 5.36 +/- 0.45 microM, respectively. The method was further extended to observe situations of the two species in mitochondria of HepG2 cells experiencing cell apoptosis that were induced by doxorubicin and photodynamic therapy (PDT).

Slurry micro-sampling technique for use in argon-helium microwave induced plasma optical emission spectrometry.

PubMed

Ślachciński, Mariusz

2016-12-01

The Flow Focusing Pneumatic Nebulizer (FFPN) working at low liquid flow rates was evaluated for the elemental analysis in slurried samples by argon-helium microwave induced plasma optical emission spectrometry (MIP-OES). The obtained results achieved were compared with commercially available V-groove Babington type nebulizer (VBPN). A univariate approach and the simplex optimization procedure were used to achieve optimized conditions and derive analytical figures of merit. Analytical performance of the micro nebulization system was characterized by a determination of the limits of detection (LODs), the precision (RSDs) and the wash-out times for Ba, Ca, Cd, Cu, Fe, Mg, Mn, Pb and Sr. The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times of the standard deviation of the blank (LOD, 3σ blank criterion, peak height) were 0.9, 0.2, 0.3, 0.2, 0.3, 0.1, 0.2, 0.4, 0.4 and 0.3ngmL -1 for Ba, Ca, Cd, Cu, Fe, Mg, Mn, Pb and Sr, respectively. The method offers relatively good precision (RSD ranged from 5% to 8%) for micro-slurry sampling analysis. Analyses of the certified reference materials (NRCC DOLT-2, GBW 07302 and SRM 2710) were performed in order to determine the accuracy available with the presented nebulization systems. The measured contents of elements in the reference materials were in satisfactory agreement with the certified values. In addition, these elements were determined in two real samples. Slurry concentration up to 3% m/v (particles <20μm), prepared in 10% m/v HCl through the application of ultrasonic agitation, was used with calibration by the standard addition technique. An ultrasonic probe was used to homogenize the slurry in the polypropylene bottle just before its introduction into the nebulizer. The nebulizers exhibited no clogging problems. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrasensitive quantification of endogenous brassinosteroids in milligram fresh plant with a quaternary ammonium derivatization reagent by pipette-tip solid-phase extraction coupled with ultra-high-performance liquid chromatography tandem mass spectrometry.

PubMed

Deng, Ting; Wu, Dapeng; Duan, Chunfeng; Guan, Yafeng

2016-07-22

Determination of endogenous brassinosteroids (BRs) in limited sample amount is vital to elucidating their tissue- and even local tissue-specific signaling pathway and physiological effects on plant growth and development. In this work, an ultra-sensitive quantification method was established for endogenous BRs in milligram fresh plant by using pipette-tip solid-phase extraction coupled with ultra-performance liquid chromatography tandem mass spectrometry (PT-SPE-UPLC-MS/MS), in which a quaternary ammonium phenyl boronic acid, 4-borono-N,N,N-trimethylbenzenaminium iodide (BTBA) was first developed for chemical derivatization of BRs. Due to the cationic quaternary ammonium group of BTBA, the ionization efficiencies of the BRs chelates with BTBA (BTBA-BRs) were enhanced by 1190-448785 times, which is the highest response enhancement factor among all derivatization reagents reported for BRs. In addition, PT-SPE packed with C18 sorbent was first used for purifying BRs from plant extracts, so the required sample amount was minimized, and recoveries higher than 91% were achieved. Under the optimized conditions, the minimal detectable amounts (MDA) of five target BRs were in the range of 27-94 amol, and the correlation coefficients (R(2)) were >0.9985 over four orders of magnitude. The relative recoveries of 75.8-104.9% were obtained with the intra- and inter-day relative standard deviations (RSDs) less than 18.7% and 19.6%, respectively. Finally, three BRs were successfully quantified in only 5mg fresh rice plant samples, and 24-epiBL can even be detected in only 0.5mg FW rice leaf segments. It is the first time that the BRs content in sub-milligram fresh plant sample has been quantified. Copyright © 2016 Elsevier B.V. All rights reserved.

Liquid chromatographic-diode-array detection multiresidue determination of rice herbicides in drinking and paddy-field water.

PubMed

Roehrs, Rafael; Zanella, Renato; Pizzuti, Ionara; Adaime, Martha B; Pareja, Lucía; Niell, Silvina; Cesio, María V; Heinzen, Horacio

2009-01-01

A sensitive, rapid, and simple multiresidue method for the simultaneous determination of six postemergence herbicides currently used in rice cultivation--metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium, and cyhalofop butyl--in drinking and paddy-field water is presented. Water samples were extracted with solid-phase extraction cartridges. Final determination was made by LC with diode-array detection. The extraction efficiencies of C18 and HLB cartridges were compared. The average recovery obtained for these compounds for the lowest spiked level (0.1 microg/L) varied from 70 to 122% for C18 and 75-119% for HLB, with RSDs of 11 and 8.3%, respectively. The method had good linearity, and the lower detection limit for the pesticides studied varied from 0.03 to 0.04 microg/L. The proposed method was also tested in paddy-field water, with recovery studies giving good results with low RSDs at 1.0 microg/L.

MAPPING GROWTH AND GRAVITY WITH ROBUST REDSHIFT SPACE DISTORTIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwan, Juliana; Lewis, Geraint F.; Linder, Eric V.

2012-04-01

Redshift space distortions (RSDs) caused by galaxy peculiar velocities provide a window onto the growth rate of large-scale structure and a method for testing general relativity. We investigate through a comparison of N-body simulations to various extensions of perturbation theory beyond the linear regime, the robustness of cosmological parameter extraction, including the gravitational growth index {gamma}. We find that the Kaiser formula and some perturbation theory approaches bias the growth rate by 1{sigma} or more relative to the fiducial at scales as large as k > 0.07 h Mpc{sup -1}. This bias propagates to estimates of the gravitational growth indexmore » as well as {Omega}{sub m} and the equation-of-state parameter and presents a significant challenge to modeling RSDs. We also determine an accurate fitting function for a combination of line-of-sight damping and higher order angular dependence that allows robust modeling of the redshift space power spectrum to substantially higher k.« less

Redefining the School District in America. Part Three of a Three-Part Series

ERIC Educational Resources Information Center

Smith, Nelson

2015-01-01

In "Redefining the School District in America," Nelson Smith reexamines existing recovery school districts (RSDs)--entities in Louisiana, Tennessee, and Michigan charged with running and turning around their state's worst schools--and assembles the most comprehensive catalog of similar initiatives underway and under consideration…

Comparative study of navigated versus freehand osteochondral graft transplantation of the knee.

PubMed

Koulalis, Dimitrios; Di Benedetto, Paolo; Citak, Mustafa; O'Loughlin, Padhraig; Pearle, Andrew D; Kendoff, Daniel O

2009-04-01

Osteochondral lesions are a common sports-related injury for which osteochondral grafting, including mosaicplasty, is an established treatment. Computer navigation has been gaining popularity in orthopaedic surgery to improve accuracy and precision. Navigation improves angle and depth matching during harvest and placement of osteochondral grafts compared with conventional freehand open technique. Controlled laboratory study. Three cadaveric knees were used. Reference markers were attached to the femur, tibia, and donor/recipient site guides. Fifteen osteochondral grafts were harvested and inserted into recipient sites with computer navigation, and 15 similar grafts were inserted freehand. The angles of graft removal and placement as well as surface congruity (graft depth) were calculated for each surgical group. The mean harvesting angle at the donor site using navigation was 4 degrees (standard deviation, 2.3 degrees ; range, 1 degrees -9 degrees ) versus 12 degrees (standard deviation, 5.5 degrees ; range, 5 degrees -24 degrees ) using freehand technique (P < .0001). The recipient plug removal angle using the navigated technique was 3.3 degrees (standard deviation, 2.1 degrees ; range, 0 degrees -9 degrees ) versus 10.7 degrees (standard deviation, 4.9 degrees ; range, 2 degrees -17 degrees ) in freehand (P < .0001). The mean navigated recipient plug placement angle was 3.6 degrees (standard deviation, 2.0 degrees ; range, 1 degrees -9 degrees ) versus 10.6 degrees (standard deviation, 4.4 degrees ; range, 3 degrees -17 degrees ) with freehand technique (P = .0001). The mean height of plug protrusion under navigation was 0.3 mm (standard deviation, 0.2 mm; range, 0-0.6 mm) versus 0.5 mm (standard deviation, 0.3 mm; range, 0.2-1.1 mm) using a freehand technique (P = .0034). Significantly greater accuracy and precision were observed in harvesting and placement of the osteochondral grafts in the navigated procedures. Clinical studies are needed to establish a benefit in vivo. Improvement in the osteochondral harvest and placement is desirable to optimize clinical outcomes. Navigation shows great potential to improve both harvest and placement precision and accuracy, thus optimizing ultimate surface congruity.

DETERMINATION OF AZOXYSTROBIN AND DIFENOCONAZOLE IN PESTICIDE PRODUCTS.

PubMed

Lazić, S; Šunjka, D

2015-01-01

In this study a high performance liquid chromatographic (HPLC-DAD) procedure has been developed for the simultaneous determination of azoxystrobin and difenoconazole in suspension concentrate pesticide formulations, with the aim of the product quality control. Azoxystrobin, strobilurin fungicide and difenoconazole (cis,trans-3-chloro-4-[4-methyl-2-(1H-1,2,4-triazol-1-ylmethyl)-1,3-dioxolan-2-yl]phenyl 4-chlorophenyl ether), triazole fungicide, are used for the protection of plants from wide spectrum of fungal diseases. For the analysis LC system an Agilent Technologies 1100 Series was used. Good separation was achieved on a Zorbax SB-C18 column (5 μm, 250 mm x 3 mm internal diameter) using a mobile phase consisting of acetonitrile/ultrapure water (90:10, v/v), at a flow rate of 0.9 ml/minute and UV detection at 218 nm. Column temperature was 25 degrees C, injected volume was 1 μl. Retention times for azoxystrobin and difenoconazole were 2.504 min and 1.963 min, respectively. This method is validated according to the requirements for new methods, which include linearity, precision, accuracy and selectivity. The method demonstrates good linearity with r2 > 0.997. The repeatability of the method, expressed as relative standard deviation (RSD, %), was found to be 1.9% for azoxystrobin and 0.5% for difenoconazole. The precision of the method was also considered to be acceptable as the experimental repeatability relative standard deviation (RSD) was lower than the RSD calculated using the Horwitz equation of 1.7% and 1.4% for azoxystrobin and difenoconazole, respectively. The accuracy of the proposed method was determined from recovery experiments through standard addition procedure. The average recoveries of the three fortification levels were 101.9% for azoxystrobin and 103.2% for difenoconazole with RSDs of 1.1% and 1.2%. The method described in this paper is simple, precise, accurate and selective and represents a new and reliable way of simultaneous determination of azoxystrobin and difenoconazole in formulated products.

Borehole deviation and correction factor data for selected wells in the eastern Snake River Plain aquifer at and near the Idaho National Laboratory, Idaho

USGS Publications Warehouse

Twining, Brian V.

2016-11-29

The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, has maintained a water-level monitoring program at the Idaho National Laboratory (INL) since 1949. The purpose of the program is to systematically measure and report water-level data to assess the eastern Snake River Plain aquifer and long term changes in groundwater recharge, discharge, movement, and storage. Water-level data are commonly used to generate potentiometric maps and used to infer increases and (or) decreases in the regional groundwater system. Well deviation is one component of water-level data that is often overlooked and is the result of the well construction and the well not being plumb. Depending on measured slant angle, where well deviation generally increases linearly with increasing slant angle, well deviation can suggest artificial anomalies in the water table. To remove the effects of well deviation, the USGS INL Project Office applies a correction factor to water-level data when a well deviation survey indicates a change in the reference elevation of greater than or equal to 0.2 ft.Borehole well deviation survey data were considered for 177 wells completed within the eastern Snake River Plain aquifer, but not all wells had deviation survey data available. As of 2016, USGS INL Project Office database includes: 57 wells with gyroscopic survey data; 100 wells with magnetic deviation survey data; 11 wells with erroneous gyroscopic data that were excluded; and, 68 wells with no deviation survey data available. Of the 57 wells with gyroscopic deviation surveys, correction factors for 16 wells ranged from 0.20 to 6.07 ft and inclination angles (SANG) ranged from 1.6 to 16.0 degrees. Of the 100 wells with magnetic deviation surveys, a correction factor for 21 wells ranged from 0.20 to 5.78 ft and SANG ranged from 1.0 to 13.8 degrees, not including the wells that did not meet the correction factor criteria of greater than or equal to 0.20 ft.Forty-seven wells had gyroscopic and magnetic deviation survey data for the same well. Datasets for both survey types were compared for the same well to determine whether magnetic survey data were consistent with gyroscopic survey data. Of those 47 wells, 96 percent showed similar correction factor estimates (≤ 0.20 ft) for both magnetic and gyroscopic well deviation surveys. A linear comparison of correction factor estimates for both magnetic and gyroscopic deviation well surveys for all 47 wells indicate good linear correlation, represented by an r-squared of 0.88. The correction factor difference between the gyroscopic and magnetic surveys for 45 of 47 wells ranged from 0.00 to 0.18 ft, not including USGS 57 and USGS 125. Wells USGS 57 and USGS 125 show a correction factor difference of 2.16 and 0.36 ft, respectively; however, review of the data files suggest erroneous SANG data for both magnetic deviation well surveys. The difference in magnetic and gyroscopic well deviation SANG measurements, for all wells, ranged from 0.0 to 0.9 degrees. These data indicate good agreement between SANG data measured using the magnetic deviation survey methods and SANG data measured using gyroscopic deviation survey methods, even for surveys collected years apart.

[An ultrafast liquid chromatography-tandem mass spectrometric method for simultaneous determination of common artificial synthetic pigments in cooked meat products].

PubMed

Chen, Xiaohong; Li, Xiaoping; Zhao, Yonggang; Pan, Shengdong; Jin, Micong

2015-07-01

A method based on ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) has been developed for the simultaneous determination of seven synthetic pigments in cooked meat product. After the cooked meat products were extracted by mixed extraction agent, purified by WAX column, the UFLC separation was performed on a Shim-pack XR-ODS II column (75 mm x 2.0 mm, 2.2 µm) with a linear gradient elution program of acetonitrile and ammonium acetate (AmAc, 5 mmol/L) as the mobile phase. Electrospray ionization was applied and operated in the negative ion mode. The limits of quantitation (LOQs) for the seven synthetic pigments were in the range of 0.7-5.0 µg/kg. The calibration curves showed good linearities for the seven analytes in their detection ranges, and the correlative coefficients (r) were more than 0.999. The recoveries were between 88.2%-106.5% with the RSDs in the range of 1.2%-5.0%. The method is sensitive, reproducible, quick and adapts to the simultaneous determination of the seven synthetic pigments in cooked meat product.

Determination of Diacetyl in Beer by a Precolumn Derivatization-HPLC-UV Method Using 4-(2,3-Dimethyl-6-quinoxalinyl)-1,2-benzenediamine as a Derivatizing Reagent.

PubMed

Wang, Ji-Yu; Wang, Xin-Jie; Hui, Xian; Hua, Shui-Hong; Li, Heng; Gao, Wen-Yun

2017-03-29

Diacetyl is an important flavoring compound in many foods, especially in beer. In the present study, we developed and validated a new precolumn derivatization HPLC-UV method for the determination of diacetyl using 4-(2,3-dimethyl-6-quinoxalinyl)-1,2-benzenediamine as a novel derivatizing reagent. After derivatization with the reagent at a pH value 4.0 at ambient temperature for 10 min, diacetyl was analyzed on an ODS column and detected at 254 nm. The results show that the correlation coefficient of the method is 0.9991 in the range of 0.10 to 100.0 μM diacetyl, and the limit of detection is 0.02 μM. The method was further evaluated in the analysis of beer samples with the recoveries ranging from 94.4 to 102.6% and RSDs from 1.36 to 3.33%. The concentrations of diacetyl in 8 beer samples were determined in the range of 0.19 to 0.42 μM. The method established in this study may be well suitable for the determination of diacetyl in beer.

Development of an immunoaffinity column method using broad-specificity monoclonal antibodies for simultaneous extraction and cleanup of quinolone and sulfonamide antibiotics in animal muscle tissues.

PubMed

Li, Cun; Wang, Zhanhui; Cao, Xingyuan; Beier, Ross C; Zhang, Suxia; Ding, Shuangyang; Li, Xiaowei; Shen, Jianzhong

2008-10-31

This paper describes a novel mixed-bed immunoaffinity column (IAC) method. The IAC was produced by coupling anti-quinolone and anti-sulfonamide broad-specificity monoclonal antibodies to Sepharose 4B for simultaneously isolating 13 quinolones (QNs) and 6 sulfonamides (SAs) from swine and chicken muscle tissues, followed by antibiotic determination using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A new broad-specificity Mab (B1A4E8) toward sulfonamides was produced using sulfamethoxazole as hapten that demonstrated cross-reactivities to 6 SAs in the range of 31-112%. IAC optimized conditions were found that allowed the IAC to be reused for selective binding of both SAs and QNs. Recoveries of all 19 antibiotics from animal muscle ranged from 72.6 to 107.6%, with RSDs below 11.3% and 15.4% for intra-day and inter-day experiments, respectively. The limit of quantification ranged from 0.5 to 3.0ng/g. The strategy used here for a mixed-bed IAC may be used to study other compounds and more than two classes of analytes simultaneously.

Ionic liquid-assisted multiwalled carbon nanotube-dispersive micro-solid phase extraction for sensitive determination of inorganic As species in garlic samples by electrothermal atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Grijalba, Alexander Castro; Escudero, Leticia B.; Wuilloud, Rodolfo G.

2015-08-01

A highly sensitive dispersive micro-solid phase extraction (D-μ-SPE) method combining an ionic liquid (IL) and multi-walled carbon nanotubes (MWCNTs) for inorganic As species (As(III) and As(V)) species separation and determination in garlic samples by electrothermal atomic absorption spectrometry (ETAAS) was developed. Trihexyl(tetradecil)phosphonium chloride IL was used to form an ion pair with the arsenomolybdate complex obtained by reaction of As(V) with molybdate ion. Afterwards, 1.0 mg of MWCNTs was dispersed for As(V) extraction and the supernatant was separated by centrifugation. MWCNTs were re-dispersed with tetradecyltrimethylammonium bromide surfactant and ultrasound followed by direct injection into the graphite furnace of ETAAS for As determination. Pyrolysis and atomization conditions were carefully studied for complete decomposition of MWCNTs and IL matrices. Under optimum conditions, an extraction efficiency of 100% and a preconcentration factor of 70 were obtained with 5 mL of garlic extract. The detection limit was 7.1 ng L- 1 and the relative standard deviations (RSDs) for six replicate measurements at 5 μg L- 1 of As were 5.4% and 4.8% for As(III) and As(V), respectively. The proposed D-μ-SPE method allowed the efficient separation and determination of inorganic As species in a complex matrix such as garlic extract.

Quantitative analysis of arsenic speciation in guano and ornithogenic sediments using microwave-assisted extraction followed by high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry.

PubMed

Lou, Chuangneng; Liu, Wenqi; Liu, Xiaodong

2014-10-15

Seabird guano is one of the main sources of nutrient fertilizers in remote coastal island areas, but guano-derived contaminants such as arsenic may cause serious threats to local ecosystems and public health issues. In this study, a new method was developed to analyze arsenic speciation in guano and ornithogenic sediments. Good extraction efficiencies of As(III) (arsenite), DMA (dimethylarsinate), MMA (monomethylarsonate) and As(V) (arsenate) were obtained by using 1.0molL(-1) orthophosphoric acid and 0.1molL(-1) ascorbic acid, followed by microwave-assisted extraction and high-performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS) detection. Under the optimized conditions, the extraction efficiencies of four arsenic species were over 80%. The relative standard deviations (RSDs) were 9.60, 6.15, 6.34 and 2.93% (n=7), and the detection limits (μgL(-1)) were 0.82, 2.38, 1.45 and 2.31 for As(III), DMA, MMA and As(V), respectively. This method was successfully used to determine arsenic speciation in the guano samples collected from the Xisha Islands of the South China Sea, and the results indicated that As(III) and As(V) were the dominant arsenic species in modern and ancient guano, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

[Simultaneous determination of four compounds in Sanjing Shuanghuanglian Oral Liquid by high performance liquid chromatography-diode array detection-electrochemical detection].

PubMed

Liu, Lin; Suo, Zhirong; Zheng, Jianbin

2006-05-01

Chlorogenic acid, caffeic acid, baicalin and luteolin in Sanjing Shuanghuanglian Oral Liquid were simultaneously detected and identified using a high performance liquid chromatography coupled with diode array detection and electrochemical detection (HPLC-DAD-ECD). The separation was performed on a Zorbax SB-C18 column (150 mm x 4.6 mm i. d., 5.0 microm). The mobile phase consisted of (A) methanol and (B) methanol-water-acetic acid (50: 50: 1, v/v/v) using a linear gradient elution of 2%A-3%A at 0-3 min, 3%A-25%A at 3-15 min, 25%A-80%A at 15-20 min. The flow rate was 0.8 mL/min. The DAD detection was used at 275 nm. The ECD detection was done at 0.7 V. The column thermostat set at 30 degrees C. The limits of detection of the 4 compounds were 1 mg/L for chlorogenic acid, 0.2 mg/L for caffeic acid, 9 mg/L for baicalin, 7 mg/L for luteolin. The average recoveries were between 96.6%-99.6% with relative standard deviations (RSDs) of 2.5%-4.1%. The method is simple, rapid, reproducible and accurate. It can be used for the routine analysis of the four compounds in Shuanghuanglian Oral Liquid.

Dispersive nano solid material-ultrasound assisted microextraction as a novel method for extraction and determination of bendiocarb and promecarb: response surface methodology.

PubMed

Khodadoust, S; Ghaedi, M; Hadjmohammadi, M R

2013-11-15

A new extraction method, based on Dispersive Nano-Solid material-Ultrasound Assisted Micro-Extraction (DNSUAME), was used for the preconcentration of the bendiocarb and promecarb pesticides in the water samples prior to high performance liquid chromatography (HPLC). The properties of NiZnS nanomaterial loaded on activated carbon (NiZnS-AC) are characterized by FT-IR, TEM, and BET. This novel nanomaterial showed great adsorptive ability towards the bendiocarb and promecarb pesticides. The effective variables such as the amount of adsorbent (mg: NiZnS-AC), the pH and ionic strength of sample solution, the vortex and ultrasonic time (min), the ultrasonic temperature (°C), and desorption volume (mL) are investigated by screening 2(7-4) experiments of Plackett-Burman (PB) design. The important variables optimized by using a central composite design (CCD) were combined by a desirability function (DF). At optimum conditions, the method has linear response over 0.0033-10 µg mL(-1) with detection limit between 0.0010 and 0.0015 µg mL(-1) with relative standard deviations (RSDs) less than 5.5% (n=3). The method has been successfully applied for the determination of the bendiocarb and promecarb pesticides in the water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

A polymeric master replication technology for mass fabrication of poly(dimethylsiloxane) microfluidic devices.

PubMed

Li, Hai-Fang; Lin, Jin-Ming; Su, Rong-Guo; Cai, Zong Wei; Uchiyama, Katsumi

2005-05-01

A protocol of producing multiple polymeric masters from an original glass master mold has been developed, which enables the production of multiple poly(dimethylsiloxane) (PDMS)-based microfluidic devices in a low-cost and efficient manner. Standard wet-etching techniques were used to fabricate an original glass master with negative features, from which more than 50 polymethylmethacrylate (PMMA) positive replica masters were rapidly created using the thermal printing technique. The time to replicate each PMMA master was as short as 20 min. The PMMA replica masters have excellent structural features and could be used to cast PDMS devices for many times. An integration geometry designed for laser-induced fluorescence (LIF) detection, which contains normal deep microfluidic channels and a much deeper optical fiber channel, was successfully transferred into PDMS devices. The positive relief on seven PMMA replica masters is replicated with regard to the negative original glass master, with a depth average variation of 0.89% for 26-microm deep microfluidic channels and 1.16% for the 90 mum deep fiber channel. The imprinted positive relief in PMMA from master-to-master is reproducible with relative standard deviations (RSDs) of 1.06% for the maximum width and 0.46% for depth in terms of the separation channel. The PDMS devices fabricated from the PMMA replica masters were characterized and applied to the separation of a fluorescein isothiocyanate (FITC)-labeled epinephrine sample.

[Determination of short chain chlorinated paraffins in leather products by solid phase extraction coupled with gas chromatography-mass spectrometry].

PubMed

Zhang, Weiya; Wan, Xin; Li, Lixia; Wang, Chengyun; Jin, Shupei; Xing, Jun

2014-10-01

The short chain chlorinated paraffins (SCCPs) are the additives frequently used in the leather production in China, but they have been put into the list of forbidden chemicals issued by European Union recently. In fact, there is not a commonly recognized method for the determination of the SCCPs in the leather products due to the serious matrix interferences from the leather products and the complex chemical structures of the SCCPs. A method of solid phase extraction coupled with gas chromatography-mass spectrometry (SPE-GC-MS) was established for the determination of the SCCPs in the leather products after the optimization of the SPE conditions. It was found that the interferences from the leather products were thor- oughly separated from the analyte of the SCCPs on a home-made solid phase extraction (SPE) column filled with silica packing while eluted with a mixed solvent of n-hexane-methylene chloride (2:1, v/v). With this method, the recoveries for the SCCPs spiked in the real leather samples varied from 90.47% to 99.00% with the relative standard deviations (RSDs) less than 6.7%, and the limits of detection (LODs) were between 0.069 and 0.110 mg/kg. This method is suitable for qualitative and quantitative analysis of SCCPs in the leather products.

Analysis of PBDEs in soil, dust, spiked lake water, and human serum samples by hollow fiber-liquid phase microextraction combined with GC-ICP-MS.

PubMed

Xiao, Qin; Hu, Bin; Duan, Jiankun; He, Man; Zu, Wanqing

2007-10-01

A novel method for the analysis of four polybrominated diphenyl ethers (PBDEs) in environmental and human serum samples based on hollow fiber-liquid phase microextraction (HF-LPME) followed by gas chromatography-inductively coupled plasma mass spectrometric (GC-ICP-MS) detection has been developed. The organic solvent in the porous hollow fiber was first dipped into the sample for extraction at a given time, and the retracted organic phase was introduced into the GC-ICP-MS for analysis. The addition of methanol has a strong effect on the HF-LPME extraction efficiency. Other significant parameters affecting the extraction efficiency of HF-LPME were also studied. HF-LPME was effective to isolate the analytes from the complex matrix. Under the optimized conditions, the detection limits of the proposed method varied from 15.2 to 40.5 ng/L. In general, the relative standard deviations (RSDs) were less than 10%. Good linearity was obtained with the correlation coefficients all better than 0.999. The proposed method is simple, quick, few microliters of organic solvent required, and is especially suitable for the analysis of the real sample with small amount available. The overall process of HF-LPME with GC-ICP-MS was applied successfully for the determination of polybrominated diphenyl ethers (PBDEs) in environmental and spiked human serum samples, and the results were satisfactory.

Simultaneous determination of multiresidual phenyl acetanilide pesticides in different food commodities by solid-phase cleanup and gas chromatography-mass spectrometry.

PubMed

Li, Yongjun; Wang, Meiling; Yan, Hongfei; Fu, Shanliang; Dai, Hua

2013-03-01

An efficient and sensitive multiresidue method has been developed for quantification and confirmation of 25 phenyl acetanilide pesticides in a wide variety of food commodities including maize, spinach, mushroom, apple, soybean, chestnut, tea, beef, cattle liver, chicken, fish, and milk. Analytes were extracted with acetone-n-hexane (1:2, v/v) followed by cleanup using SPE. Several types of adsorbents were evaluated. Neutral aluminum and graphitized carbon black cartridge showed good cleanup efficiency. The extract was determined by GC-MS in the selected ion monitoring mode using one target and two qualitative ions for each analyte. The limits of detection were 0.01 mg/kg for all analytes. The average recoveries ranged from 66.9 to 110.6% (mean 88.8%) and RSDs were in the range 2.0-19% (mean 10.5%) across three fortification levels. The proposed method was successfully applied to real samples in routine analysis and a satisfactory result was obtained. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrasound-assisted dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet followed by gas chromatography for the determination of eight pyrethroid pesticides in tea samples.

PubMed

Hou, Xiaohong; Zheng, Xin; Zhang, Conglu; Ma, Xiaowei; Ling, Qiyuan; Zhao, Longshan

2014-10-15

A novel ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet method (UA-DLLME-SFO) combined with gas chromatography (GC) was developed for the determination of eight pyrethroid pesticides in tea for the first time. After ultrasound and centrifugation, 1-dodecanol and ethanol was used as the extraction and dispersive solvent, respectively. A series of parameters, including extraction solvent and volume, dispersive solvent and volume, extraction time, pH, and ultrasonic time influencing the microextraction efficiency were systematically investigated. Under the optimal conditions, the enrichment factors (EFs) were from 292 to 883 for the eight analytes. The linear ranges for the analytes were from 5 to 100μg/kg. The method recoveries ranged from 92.1% to 99.6%, with the corresponding RSDs less than 6.0%. The developed method was considered to be simple, fast, and precise to satisfy the requirements of the residual analysis of pyrethroid pesticides. Copyright © 2014 Elsevier B.V. All rights reserved.

40 CFR 266.106 - Standards to control metals emissions.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-specific doses (RSDs) are listed for the carcinogenic metals. The RSD for a metal is the acceptable ambient... RSD as described in paragraph (d)(3) of this section. (3) Carcinogenic metals. For the carcinogenic... person resides on site) to the risk-specific dose (RSD) for all carcinogenic metals emitted shall not...

40 CFR 266.106 - Standards to control metals emissions.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-specific doses (RSDs) are listed for the carcinogenic metals. The RSD for a metal is the acceptable ambient... RSD as described in paragraph (d)(3) of this section. (3) Carcinogenic metals. For the carcinogenic... person resides on site) to the risk-specific dose (RSD) for all carcinogenic metals emitted shall not...

40 CFR 266.106 - Standards to control metals emissions.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-specific doses (RSDs) are listed for the carcinogenic metals. The RSD for a metal is the acceptable ambient... RSD as described in paragraph (d)(3) of this section. (3) Carcinogenic metals. For the carcinogenic... person resides on site) to the risk-specific dose (RSD) for all carcinogenic metals emitted shall not...

Quantitative Determination of Cannabinoids in Cannabis and Cannabis Products Using Ultra-High-Performance Supercritical Fluid Chromatography and Diode Array/Mass Spectrometric Detection.

PubMed

Wang, Mei; Wang, Yan-Hong; Avula, Bharathi; Radwan, Mohamed M; Wanas, Amira S; Mehmedic, Zlatko; van Antwerp, John; ElSohly, Mahmoud A; Khan, Ikhlas A

2017-05-01

Ultra-high-performance supercritical fluid chromatography (UHPSFC) is an efficient analytical technique and has not been fully employed for the analysis of cannabis. Here, a novel method was developed for the analysis of 30 cannabis plant extracts and preparations using UHPSFC/PDA-MS. Nine of the most abundant cannabinoids, viz. CBD, ∆ 8 -THC, THCV, ∆ 9 -THC, CBN, CBG, THCA-A, CBDA, and CBGA, were quantitatively determined (RSDs < 6.9%). Unlike GC methods, no derivatization or decarboxylation was required prior to UHPSFC analysis. The UHPSFC chromatographic separation of cannabinoids displayed an inverse elution order compared to UHPLC. Combining with PDA-MS, this orthogonality is valuable for discrimination of cannabinoids in complex matrices. The developed method was validated, and the quantification results were compared with a standard UHPLC method. The RSDs of these two methods were within ±13.0%. Finally, chemometric analysis including principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were used to differentiate between cannabis samples. © 2016 American Academy of Forensic Sciences.

A proof for Rhiel's range estimator of the coefficient of variation for skewed distributions.

PubMed

Rhiel, G Steven

2007-02-01

In this research study is proof that the coefficient of variation (CV(high-low)) calculated from the highest and lowest values in a set of data is applicable to specific skewed distributions with varying means and standard deviations. Earlier Rhiel provided values for d(n), the standardized mean range, and a(n), an adjustment for bias in the range estimator of micro. These values are used in estimating the coefficient of variation from the range for skewed distributions. The d(n) and an values were specified for specific skewed distributions with a fixed mean and standard deviation. In this proof it is shown that the d(n) and an values are applicable for the specific skewed distributions when the mean and standard deviation can take on differing values. This will give the researcher confidence in using this statistic for skewed distributions regardless of the mean and standard deviation.

Silica/graphene oxide nanocomposites: Potential adsorbents for solid phase extraction of trace aflatoxins in cereal crops coupled with high performance liquid chromatography.

PubMed

Yu, Li; Ma, Fei; Ding, Xiaoxia; Wang, Hengling; Li, Peiwu

2018-04-15

Graphene oxide wrapped silica nanocomposites were synthesized and selected as solid phase extraction adsorbents for high performance liquid chromatography analysis of aflatoxins. The major parameters affecting extraction efficiency were optimized, including the amount of adsorbents, extraction time and desorption conditions. The limit of detections and the limit of quantifications were from 0.1 to 0.3 µg/kg and from 0.3 to 1.0 µg/kg, respectively. The recoveries of aflatoxins in the spiked maize and rice samples were in the range of 76.8-104.7% and 81.1-106.9%, respectively, and with the RSDs less than 12.4%. The proposed method was proven to be simple, rapid and reliable for routine analysis of aflatoxins in crops. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solid-phase microextraction of benzimidazole fungicides in environmental liquid samples and HPLC-fluorescence determination.

PubMed

López Monzón, A; Vega Moreno, D; Torres Padrón, M E; Sosa Ferrera, Z; Santana Rodríguez, J J

2007-03-01

Solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC) with fluorescence detection was optimized for extraction and determination of four benzimidazole fungicides (benomyl, carbendazim, thiabendazole, and fuberidazole) in water. We studied extraction and desorption conditions, for example fiber type, extraction time, ionic strength, extraction temperature, and desorption time to achieve the maximum efficiency in the extraction. Results indicate that SPME using a Carboxen-polydimethylsiloxane 75 microm (CAR-PDMS) fiber is suitable for extraction of these types of compound. Final analysis of benzimidazole fungicides was performed by HPLC with fluorescence detection. Recoveries ranged from 80.6 to 119.6 with RSDs below 9% and limits of detection between 0.03 and 1.30 ng mL-1 for the different analytes. The optimized procedure was applied successfully to the determination of benzimidazole fungicides mixtures in environmental water samples (sea, sewage, and ground water).

Comparison of QuEChERS sample preparation methods for the analysis of pesticide residues in canned and fresh peach.

PubMed

Costa, Fabiane Pinho; Caldas, Sergiane Souza; Primel, Ednei Gilberto

2014-12-15

Original, citrate and acetate QuEChERS methods were studied in order to evaluate the extraction efficiency and the matrix effect in the extraction of pesticides from canned peach samples. Determinations were performed by gas chromatography coupled to mass spectrometry (GC-MS). The proposed method with extraction using the original QuEChERS method and determination by GC-MS was validated. LOQs ranged between 1 and 10 μg kg(-1) and all analytical curves showed r values higher than 0.99. Recovery values varied from 69% to 125% with RSDs less than 20%. The matrix effect was evaluated and most compounds showed signal enrichment. Robustness was demonstrated using fresh peaches, which provided recovery values within acceptable limits. The applicability of the method was verified and residues of tebuconazole and dimethoate were found in the samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dissipation and residues of monosultap in rice plant and environment.

PubMed

Zhang, Fengzu; Wang, Lei; Zhou, Li; Pan, Canping

2012-03-01

A modified method for the analysis of monosultap residue in rice plant and environment was developed and validated. Monosultap residue dynamics and final residues in supervised field trials at GAP conditions were studied. At fortification levels of 0.05, 0.5 and 1 mg kg(-1), it was shown that recoveries ranged from 75.0% to 109.2% with RSDs of 1.2-5.1% (n = 5). The dissipation experiments showed the half-lives (T(1/2)) of monosultap in water, soil and rice plants were 1.1-1.9, 1.4-2.1 and 1.3-2.1 days, respectively. At pre-harvest intervals (PHI) of 21 and 30 days, monosultap residue were 0.01-0.06 mg kg(-1) in soil, 0.01-0.19 mg kg(-1) in rice plants, and 0.01-0.09 mg kg(-1) in husked rice.

Nonlinear elastic effects on the energy flux deviation of ultrasonic waves in gr/ep composites

NASA Technical Reports Server (NTRS)

Prosser, William H.; Kriz, R. D.; Fitting, Dale W.

1992-01-01

The effects of nonlinear elasticity on energy flux deviation in undirectional gr/ep composites are examined. The shift in the flux deviation is modeled using acoustoelasticity theory and the second- and third-order elastic stiffness coefficients for T300/5208 gr/ep. Two conditions of applied uniaxial stress are considered. In the first case, the direction of applied uniaxial stress was along the fiber axis (x3), while in the second case it was perpendicular to the fiber axis along the laminate stacking direction (x1). For both conditions, the change in the energy flux deviation angle from the condition of zero applied stress is computed over the range of propagation directions of 0 to 60 deg from the fiber axis at two-degree intervals. A positive flux deviation angle implies the energy deviates away from the fiber direction toward the x1 axis, while a negative deviation means that the energy deviates toward the fibers. Over this range of fiber orientation angles, the energy of the quasi-longitudinal and pure mode transverse waves deviates toward the fibers, while that of the quasi-transverse mode deviates away from the fibers.

Octadecyl functionalized core-shell magnetic silica nanoparticle as a powerful nanocomposite sorbent to extract urinary volatile organic metabolites.

PubMed

Qiao, Zheng; Perestrelo, Rosa; Reyes-Gallardo, Emilia M; Lucena, R; Cárdenas, S; Rodrigues, João; Câmara, José S

2015-05-08

In this present study, magnetic Fe3O4@SiO2 nanoparticles (MNPs) functionalized with octadecyl groups (Fe3O4@SiO2-C18 NPs) were synthesized, characterized and employed, for the first time, as powerful nanosorbent to extract endogenous volatile organic metabolites (EVOMs) namely, hexanal, heptanal, decanal, benzaldehyde, 4-heptanone, 5-methyl-2-furfural and phenol, described as potential biomarkers of cancer, from human urine. By using co-precipitation, surface modification methods, the carbon-ferromagnetic nanocomposite was synthesized and characterized by infrared spectrum (IR) and transmission electron microscopy (TEM). By coupling with gas chromatography-mass spectrometry (GC-qMS), a reliable, sensitive and cost-effective method was validated. To test the extraction efficiency of the carbon-ferromagnetic nanocomposite toward urinary EVOMs experimental variables affecting the extraction performance, including nanosorbent amount, adsorption time, elution time, and nature of elution solvent, were investigated in detail. The extraction process was performed by dispersing Fe3O4@SiO2-C18 NPs into working solution containing targeted VOMs, and into urine samples, and then eluted with an adequate organic solvent. The eluate was collected, concentrated and analyzed by GC-qMS. Under the optimized conditions, the LODs and LOQs achieved were in the range of 9.7-57.3 and 32.4-190.9ng/mL, respectively. Calibration curves were linear (r(2)≥0. 988) over the concentration ranges from 0.25 to 250ng/mL. In addition, a satisfying reproducibility was achieved by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 3 and 11%, respectively. The method also afforded satisfactory results in terms of the matrix effect (72.8-96.1%) and recoveries (accuracy) higher than 75.1% for most of the studied EVOMs. The Fe3O4@SiO2-C18 NPs-based sorbent extraction combined with GC-qMS revealed that the new nanosorbent had a strong ability to retain the target metabolites providing a new, reliable and high throughput strategy for isolation of targeted EVOMs in human urine, suggesting their potential to be applied in other EVOMs. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous and enantioselective determination of cis-epoxiconazole and indoxacarb residues in various teas, tea infusion and soil samples by chiral high performance liquid chromatography coupled with tandem quadrupole-time-of-flight mass spectrometry.

PubMed

Zhang, Xinzhong; Luo, Fengjian; Lou, Zhengyun; Lu, Meiling; Chen, Zongmao

2014-09-12

A novel and sensitive method for simultaneous enantiomeric analysis of two pesticides-cis-epoxiconazole and indoxacarb-in various teas, black tea infusion, and soil samples has been developed. The samples were initially subjected to acetonitrile extraction followed by cleanup using lab-made florisil/graphitized carbon black mixed solid phase extraction (SPE) column (for the different teas and soil samples) and a BondElut C18-SPE column (for the black tea infusion samples). Separation of the analytes was performed on a chiral stationary phase using high performance liquid chromatography (HPLC) under a reversed-phase isocratic elution mode followed by tandem quadrupole time-of-flight mass spectrometry (Q-TOF/MS) detection. The mobile phase components, mobile phase ratios, flow rates, column temperatures, and MS parameters were all optimized to reach high sensitivity and selectivity, good peak shape, and satisfactory resolution. The performance of the method was evaluated based on the sensitivity, linearity, accuracy, precision, and matrix effects. Under optimal conditions, for the various teas (green tea, black tea, and puer tea), fresh tea leaf, soil and black tea infusion samples spiked at low, medium, and high levels, the mean recoveries for the four enantiomers ranged from 61.0% to 129.7% with most relative standard deviations (RSDs) being 17.1% or below. Good linearity can be achieved with regression coefficients (R) of 0.9915 or above for all target enantiomers, and matrix-matched calibration concentration ranging from 5.0 to 1000μg/L. The limits of detection (LODs) for all four target enantiomers were 1.4μg/kg or below in the different teas and soil samples and 0.05μg/kg or below in the black tea infusion, whereas the limits of quantification (LOQs) for those did not exceed 5.0μg/kg and 0.2μg/L, respectively. The proposed method is convenient and reliable and has been applied to real tea samples screening. It has also been extended for studies on the degradation kinetics and environmental behaviors in the field trials, providing additional information for reliable risk assessment of these chiral pesticides. Copyright © 2014 Elsevier B.V. All rights reserved.

High sensitivity simultaneous determination in hair of the major constituents of ecstasy (3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine and 3,4-methylene-dioxyethylamphetamine) by high-performance liquid chromatography with direct fluorescence detection.

PubMed

Tagliaro, F; De Battisti, Z; Groppi, A; Nakahara, Y; Scarcella, D; Valentini, R; Marigo, M

1999-02-19

A simple, but sensitive and specific high-performance liquid chromatographic assay for the simultaneous determination of the major constituents of "ecstasy" [i.e. 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxyethylamphetamine (MDE)] with direct fluorimetric detection, particularly intended for the routine analysis of hair, is described. Hair samples (100 mg) were overnight incubated in 1 ml of 0.25 M HCl at 45 degrees C and extracted with a commercial liquid-liquid method. The dried residue reconstituted with 500 microl of 0.05 M NaH2PO4 pH 5.2 was injected. Isocratic reversed-phase liquid chromatography was carried out on a column (250x4.6 mm I.D.) packed with spherical 5-microm poly(styrene-divinylbenzene) particles; the mobile phase was composed of 0.1 M potassium phosphate (pH 3)-acetonitrile (82:18). The excitation and the emission wavelengths were set to 285 and 320 nm, respectively. Under the described conditions, MDA, MDMA and MDE eluted in symmetric peaks with an analysis time of 30 min. The limit of detection was lower than 1 ng/ml, with a signal-to-noise ratio of 5, for each compound in solution, allowing a cut-off of 0.1 ng/mg in the hair matrix to be established. The intra-day precision (n = 6) of the assay was characterised by RSDs between 1.0 and 3.0% and between 0.52 and 0.88% for concentrations of 10 and 100 ng/ml, respectively; in day-to-day precision tests (n = 6), RSDs ranged between 5.12 and 11.12%, respectively, for the same concentrations. Interferences from as many as 92 therapeutic and/or abused drugs currently in use in the population were excluded, including N-methyl-1-(3,4-methylenedioxyphenyl)-2 butanamine (MBDB).

Modern sedimentation on the shoreface and inner continental shelf at wrightsville beach, North Carolina, U.S.A

USGS Publications Warehouse

Thieler, R.E.; Pilkey, O.H.; Cleary, W.J.; Schwab, W.C.

2001-01-01

The geologic framework and surficial morphology of the shoreface and inner continental shelf off the Wrightsville Beach, North Carolina, barrier island were mapped using high-resolution sidescansonar, bathyme??trie, and seismic-reflection surveying techniques, a suite of over 200 diver vibracores, and extensive seafloor observations by divers. The inner shelf is a sediment-starved, active surface of marine erosion; modern sediments, where present, form a patchy veneer over Tertiary and Quaternary units. The lithology of the underlying units exerts a primary control on the distribution, texture, and composition of surficial sediments, as well as inner-shelf bathymetry. The shoreface is dominated by a linear, cross-shore morphology of rippled scour depressions (RSDs) extending from just seaward of the surf zone onto the inner shelf. On the upper shoreface, the RSDs are incised up to l m below surrounding areas of fine sand, and have an asymmetric cross section that is steeper-sided to the north. On the inner shelf, the RSDs have a similar but more subdued cross-sectional profile. The depressions are floored primarily by shell hash and quartz gravel. Vibracore data show a thick (up to 1.5 m) sequence of RSD sediments that unconformably overlies ancient coastal lithosomes. In this sediment-starved inner shelf setting, rippled scour depressions probably form initially on preexisting coarse-sediment substrates such as modern lag deposits of paleofluvial channel lithosomes or ancient tidal inlet thalwegs. Interannual observations of seafloor morphologic change and the longer-term record contained in vibracores suggest that the present seafloor morphology is either relatively stable or represents a recurring, preferential morphologic state to which the seafloor returns after storm-induced perturbations. The apparent stability is interpreted to be the result of interactions at several scales that contribute to a repeating, self-reinforcing pattern of forcing and sedimentary response which ultimately causes the RSDs to be maintained as sediment-starved bedforms responding to both along-shore and acrossshore flows. Sediment accumulation from over 30 years of extensive beach nourishment at Wrightsville Beach appears to have exceeded the local shoreface accommodation space, resulting in the "leaking" of beach and shoreface sediment to the inner shelf. A macroscopically identifiable beach nourishment sediment on the shoreface and inner shelf was used to identify the decadal-scale pattern of sediment dispersal. The nourishment sediment is present in a seaward-thinning wedge that extends from the beach over a kilometer onto the inner shelf to waters depths of 14 m. This wedge is best developed offshore of the shoreline segment that has received the greatest volume of beach nourishment. 

Longitudinal and cross-sectional analyses of visual field progression in participants of the Ocular Hypertension Treatment Study.

PubMed

Artes, Paul H; Chauhan, Balwantray C; Keltner, John L; Cello, Kim E; Johnson, Chris A; Anderson, Douglas R; Gordon, Mae O; Kass, Michael A

2010-12-01

To assess agreement between longitudinal and cross-sectional analyses for determining visual field progression in data from the Ocular Hypertension Treatment Study. Visual field data from 3088 eyes of 1570 participants (median follow-up, 7 years) were analyzed. Longitudinal analyses were performed using change probability with total and pattern deviation, and cross-sectional analyses were performed using the glaucoma hemifield test, corrected pattern standard deviation, and mean deviation. The rates of mean deviation and general height change were compared to estimate the degree of diffuse loss in emerging glaucoma. Agreement on progression in longitudinal and cross-sectional analyses ranged from 50% to 61% and remained nearly constant across a wide range of criteria. In contrast, agreement on absence of progression ranged from 97.0% to 99.7%, being highest for the stricter criteria. Analyses of pattern deviation were more conservative than analyses of total deviation, with a 3 to 5 times lesser incidence of progression. Most participants developing field loss had both diffuse and focal changes. Despite considerable overall agreement, 40% to 50% of eyes identified as having progressed with either longitudinal or cross-sectional analyses were identified with only one of the analyses. Because diffuse change is part of early glaucomatous damage, pattern deviation analyses may underestimate progression in patients with ocular hypertension.

Application of a GCM Ensemble Seasonal Climate Forecasts to Crop Yield Prediction in East Africa

NASA Astrophysics Data System (ADS)

Ogutu, G.; Franssen, W.; Supit, I.; Hutjes, R. W. A.

2016-12-01

We evaluated the potential use of ECMWF System-4 seasonal climate forecasts (S4) for impacts analysis over East Africa. Using the 15 member, 7 months ensemble forecasts initiated every month for 1981-2010, we tested precipitation (tp), air temperature (tas) and surface shortwave radiation (rsds) forecast skill against the WATCH forcing Data ERA-Interim (WFDEI) re-analysis and other data. We used these forecasts as input in the WOFOST crop model to predict maize yields. Forecast skill is assessed using anomaly correlation (ACC), Ranked Probability Skill Score (RPSS) and the Relative Operating Curve Skill Score (ROCSS) for MAM, JJA and OND growing seasons. Predicted maize yields (S4-yields) are verified against historical observed FAO and nationally reported (NAT) yield statistics, and yields from the same crop model forced by WFDEI (WFDEI-yields). Predictability of the climate forecasts vary with season, location and lead-time. The OND tp forecasts show skill over a larger area up to three months lead-time compared to MAM and JJA. Upper- and lower-tercile tp forecasts are 20-80% better than climatology. Good tas forecast skill is apparent with three months lead-time. The rsds is less skillful than tp and tas in all seasons when verified against WFDEI but higher against others. S4-forecasts captures ENSO related anomalous years with region dependent skill. Anomalous ENSO influence is also seen in simulated yields. Focussing on the main sowing dates in the northern (July), equatorial (March-April) and southern (December) regions, WFDEI-yields are lower than FAO and NAT but anomalies are comparable. Yield anomalies are predictable 3-months before sowing in most of the regions. Differences in interannual variability in the range of ±40% may be related to sensitivity of WOFOST to drought stress while the ACCs are largely positive ranging from 0.3 to 0.6. Above and below-normal yields are predictable with 2-months lead time. We evidenced a potential use of seasonal climate forecasts with a crop simulation model to predict anomalous maize yields over East Africa. The findings open a window to better use of climate forecasts in food security early warning systems, and pre-season policy and farm management decisions.

Redefining the School District in Michigan. Part Two of a Three-Part Series

ERIC Educational Resources Information Center

Smith, Nelson

2014-01-01

What happens when policymakers create statewide school districts to turn around their worst-performing public schools? In Louisiana and Tennessee, Recovery School Districts (RSDs) have made modest-to-strong progress for kids and serve as national models for what the future of education governance might hold. In the Great Lakes State, the story is…

MOVING LEFT OF BOOM: LEVERAGING TITLE 32 NATIONAL GUARDSMEN TO SHARE CYBER THREAT INTELLIGENCE WITH STATE AUTHORITIES

DTIC Science & Technology

2016-06-01

mission, one weekend per month in training periods called Regularly Scheduled Drills ( RSD ) and 15 days per year, called Annual Training (AT).16 There...however during RSDs or AT military technicians convert to military members the same as drill status guardsmen. Similar to an AGR, the role of a

Social smile reproducibility using 3-D stereophotogrammetry and reverse engineering technology.

PubMed

Dindaroğlu, Furkan; Duran, Gökhan Serhat; Görgülü, Serkan; Yetkiner, Enver

2016-05-01

To assess the range of social smile reproducibility using 3-D stereophotogrammetry and reverse engineering technology. Social smile images of white adolescents (N  =  15, mean age  =  15.4 ±1.5 years; range  =  14-17 years) were obtained using 3dMDFlex (3dMD, Atlanta, Ga). Each participant was asked to produce 16 social smiles at 3-minute intervals. All images were obtained in natural head position. Alignment of images, segmentation of smile area, and 3-D deviation analysis were carried out using Geomagic Control software (3D Systems Inc, Cary, NC). A single image was taken as a reference, and the remaining 15 images were compared with the reference image to evaluate positive and negative deviations. The differences between the mean deviation limits of participants with the highest and the lowest deviations and the total mean deviations were evaluated using Bland-Altman Plots. Minimum and maximum deviations of a single image from the reference image were 0.34 and 2.69 mm, respectively. Lowest deviation between two images was within 0.5 mm and 1.54 mm among all participants (mean, 0.96 ± 0.21 mm), and the highest deviation was between 0.41 mm and 2.69 mm (mean, 1.53 ± 0.46 mm). For a single patient, when all alignments were considered together, the mean deviation was between 0.32 ± 0.10 mm and 0.59 ± 0.24 mm. Mean deviation for one image was between 0.14 and 1.21 mm. The range of reproducibility of the social smile presented individual variability, but this variation was not clinically significant or detectable under routine clinical observation.

Depth and lateral deviations in guided implant surgery: an RCT comparing guided surgery with mental navigation or the use of a pilot-drill template.

PubMed

Vercruyssen, M; Coucke, W; Naert, I; Jacobs, R; Teughels, W; Quirynen, M

2015-11-01

To assess the accuracy of guided surgery compared with mental navigation or the use of a pilot-drill template in fully edentulous patients. Sixty consecutive patients (72 jaws), requiring four to six implants (maxilla or mandible), were randomly assigned to one of the following treatment modalities: Materialise Universal(®) mucosa, Materialise Universal(®) bone, Facilitate(™) mucosa, Facilitate(™) bone, mental navigation, or a pilot-drill template. Accuracy was assessed by matching the planning CT with a postoperative CBCT. Deviations were registered in a vertical (depth) and horizontal (lateral) plane. The latter further subdivided into BL (bucco-lingual) and MD (mesio-distal) deviations. The overall mean vertical deviation for the guided surgery groups was 0.9 mm ± 0.8 (range: 0.0-3.7) and 0.9 mm ± 0.6 (range: 0.0-2.9) in a horizontal direction. For the non-guided groups, this was 1.7 mm ± 1.3 (range: 0.0-6.4) and 2.1 mm ± 1.4 (range 0.0-8.5), respectively (P < 0.05). The overall mean deviation for the guided surgery groups in MD direction was 0.6 mm ± 0.5 (range: 0.0-2.5) and 0.5 mm ± 0.5 (range: 0.0-2.9) in BL direction. For the non-guided groups, this was 1.8 mm ± 1.4 (range: 0.0-8.3) and 0.7 mm ± 0.6 (range 0.0-2.9), respectively. The deviation in MD direction was significantly higher in the non-guided groups (P = 0.0002). The most important inaccuracy with guided surgery is in vertical direction (depth). The inaccuracy in MD or BL direction is clearly less. For non-guided surgery, the inaccuracy is significantly higher. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Synthesis of g-C3N4/Fe3O4 nanocomposites and application as a new sorbent for solid phase extraction of polycyclic aromatic hydrocarbons in water samples.

PubMed

Wang, Man; Cui, Shihai; Yang, Xiaodi; Bi, Wentao

2015-01-01

An easy preparation of g-C3N4/Fe3O4 nanocomposites by chemical co-precipitation has been demonstrated. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The high affinity of g-C3N4 toward polycyclic aromatic hydrocarbons and the magnetic behavior of Fe3O4 were combined to provide an efficient and simple magnetic solid phase extraction (MSPE). The adsorption and desorption of polycyclic aromatic hydrocarbons on g-C3N4/Fe3O4 were examined. Different factors affecting the magnetic solid phase extraction of polycyclic aromatic hydrocarbons were assessed in terms of adsorption, desorption, and recovery. Under the optimized conditions, the proposed method showed good limits of detection (LOD, S/N=3) in the range of 0.05-0.1 ng mL(-1) and precision in the range of 1.8-5.3% (RSDs, n=3). This method was also successfully applied to the analysis of real water samples; good spiked recoveries over the range of 80.0-99.8% were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

Biosensor for on-line fluorescent detection of trifluoroperazine based on genetically modified calmodulin.

PubMed

González-Andrade, Martin; Benito-Peña, Elena; Mata, Rachel; Moreno-Bondi, Maria C

2012-04-01

This paper describes the development of a novel on-line biosensor based on a fluorescently labeled human calmodulin (CaM), hCaM M124C-mBBr, immobilized on controlled-pore glass (CPG), for the analysis of trifluoroperazine (TFP); a phenothiazine drug in human urine samples. The device was automated by packing hCaM M124C-mBBr-CPG in a continuous-flow microcell connected to a monitoring system, composed of a bifurcated optical fiber coupled to a spectrofluorometer. Operating parameters of the on-line biosensor (flow rate, sample injection volume, and carrier solution and buffer pH) were studied and optimized. Under the optimal conditions, the biosensor provides a detection and a quantification limit of 0.24 and 0.52 μg mL(-1), respectively, and a dynamic range from 0.52 to 61.05 μg mL(-1) TFP (n = 5, correlation coefficient 0.998). The response time (t(100)) was shorter than 42 s (recovery time <4.5 min) and reproducibility and repeatability of the TFP measurements, within the linear response range, were lower than 1.4 and 2.7%, respectively. The device was successfully applied to the analysis of TFP in spiked human urine samples with recoveries ranging between 97 and 101% and with RSDs lower than 5.9%.

Electro-driven extraction of inorganic anions from water samples and water miscible organic solvents and analysis by ion chromatography.

PubMed

Nojavan, Saeed; Bidarmanesh, Tina; Memarzadeh, Farkhondeh; Chalavi, Soheila

2014-09-01

A simple electromembrane extraction (EME) procedure combined with ion chromatography (IC) was developed to quantify inorganic anions in different pure water samples and water miscible organic solvents. The parameters affecting extraction performance, such as supported liquid membrane (SLM) solvent, extraction time, pH of donor and acceptor solutions, and extraction voltage were optimized. The optimized EME conditions were as follows: 1-heptanol was used as the SLM solvent, the extraction time was 10 min, pHs of the acceptor and donor solutions were 10 and 7, respectively, and the extraction voltage was 15 V. The mobile phase used for IC was a combination of 1.8 mM sodium carbonate and 1.7 mM sodium bicarbonate. Under these optimized conditions, all anions had enrichment factors ranging from 67 to 117 with RSDs between 7.3 and 13.5% (n = 5). Good linearity values ranging from 2 to 1200 ng/mL with coefficients of determination (R(2) ) between 0.987 and 0.999 were obtained. The LODs of the EME-IC method ranged from 0.6 to 7.5 ng/mL. The developed method was applied to different samples to evaluate the feasibility of the method for real applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Employing Solid Phase Microextraction as Extraction Tool for Pesticide Residues in Traditional Medicinal Plants

PubMed Central

Gondo, Thamani T.; Mmualefe, Lesego C.; Okatch, Harriet

2016-01-01

HS-SPME was optimised using blank plant sample for analysis of organochlorine pesticides (OCPs) of varying polarities in selected medicinal plants obtained from northern part of Botswana, where OCPs such as DDT and endosulfan have been historically applied to control disease carrying vectors (mosquitos and tsetse fly). The optimised SPME parameters were used to isolate analytes from root samples of five medicinal plants obtained from Maun and Kasane, Botswana. The final analytes determination was done with a gas chromatograph equipped with GC-ECD and analyte was confirmed using electron ionisation mass spectrometer (GC-MS). Dieldrin was the only pesticide detected and confirmed with MS in the Terminalia sericea sample obtained from Kasane. The method was validated and the analyte recoveries ranged from 69.58 ± 7.20 to 113 ± 15.44%, with RSDs ranging from 1.19 to 17.97%. The method indicated good linearity (R 2 > 0.9900) in the range of 2 to 100 ng g−1. The method also proved to be sensitive with low limits of detection (LODs) ranging from 0.48 ± 0.16 to 1.50 ± 0.50 ng g−1. It can be concluded that SPME was successfully utilized as a sampling and extraction tool for pesticides of diverse polarities in root samples of medicinal plants. PMID:27725893

40 CFR 89.320 - Carbon monoxide analyzer calibration.

Code of Federal Regulations, 2014 CFR

2014-07-01

... monoxide as described in this section. (b) Initial and periodic interference check. Prior to its... engineering practice. For each range calibrated, if the deviation from a least-squares best-fit straight line... range. If the deviation exceeds these limits, the best-fit non-linear equation which represents the data...

40 CFR 89.320 - Carbon monoxide analyzer calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... monoxide as described in this section. (b) Initial and periodic interference check. Prior to its... engineering practice. For each range calibrated, if the deviation from a least-squares best-fit straight line... range. If the deviation exceeds these limits, the best-fit non-linear equation which represents the data...

40 CFR 89.320 - Carbon monoxide analyzer calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

... monoxide as described in this section. (b) Initial and periodic interference check. Prior to its... engineering practice. For each range calibrated, if the deviation from a least-squares best-fit straight line... range. If the deviation exceeds these limits, the best-fit non-linear equation which represents the data...

40 CFR 89.320 - Carbon monoxide analyzer calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... monoxide as described in this section. (b) Initial and periodic interference check. Prior to its... engineering practice. For each range calibrated, if the deviation from a least-squares best-fit straight line... range. If the deviation exceeds these limits, the best-fit non-linear equation which represents the data...

Fourier analysis of multitracer cosmological surveys

NASA Astrophysics Data System (ADS)

Abramo, L. Raul; Secco, Lucas F.; Loureiro, Arthur

2016-02-01

We present optimal quadratic estimators for the Fourier analysis of cosmological surveys that detect several different types of tracers of large-scale structure. Our estimators can be used to simultaneously fit the matter power spectrum and the biases of the tracers - as well as redshift-space distortions (RSDs), non-Gaussianities (NGs), or any other effects that are manifested through differences between the clusterings of distinct species of tracers. Our estimators reduce to the one by Feldman, Kaiser & Peacock (FKP) in the case of a survey consisting of a single species of tracer. We show that the multitracer estimators are unbiased, and that their covariance is given by the inverse of the multitracer Fisher matrix. When the biases, RSDs and NGs are fixed to their fiducial values, and one is only interested in measuring the underlying power spectrum, our estimators are projected into the estimator found by Percival, Verde & Peacock. We have tested our estimators on simple (lognormal) simulated galaxy maps, and we show that it performs as expected, being either equivalent or superior to the FKP method in all cases we analysed. Finally, we have shown how to extend the multitracer technique to include the one-halo term of the power spectrum.

Applicability of two automated disintegration apparatuses for rapidly disintegrating (mini)tablets.

PubMed

Sieber, Daniel; Lazzari, Alessia; Quodbach, Julian; Pein, Miriam

2017-03-01

Orally disintegrating (mini)tablets (OD(M)Ts) are of interest in the field of pharmaceutics. Their orodispersible character is defined by the disintegration time, which is measured with a basket apparatus according to the European Pharmacopoeia. This method, however, lacks applicability for ODTs and especially ODMTs. New disintegration apparatuses have been described in literature, but a qualification to assess the applicability has not been described. A qualification procedure for two automated disintegration apparatuses, OD-mate and Hermes apparatus, is introduced. Aspects of the operational qualification as well as precision and accuracy regarding a performance qualification were evaluated for both apparatuses analog to the ICH guideline Q2. While the OQ study is performed separately for each apparatus, accuracy and precision were performed following the same protocol for both testers. Small RSDs (16.9% OD-mate; 15.2% Hermes compared to 32.3% for the pharmacopeial method) were found despite very fast disintegration times (1.5 s for both apparatuses). By comparing these RSDs to practical examples, the authors propose threshold values for repeatability depending on the mean disintegration time. Obtained results from the qualification were used to assess the applicability of both apparatuses.

Evaluation of the QuEChERS sample preparation approach for the analysis of pesticide residues in olives.

PubMed

Cunha, Sara C; Lehotay, Steven J; Mastovska, Katerina; Fernandes, José O; Beatriz, Maria; Oliveira, P P

2007-03-01

This paper describes the use of a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for extraction and cleanup of 16 pesticide residues of interest in olives and olive oil. These products contain a high lipid content, which can adversely affect pesticide recoveries and harm traditional chromatographic systems. For extraction, the main factors (oil and water content) were studied and optimized in experiments to maximize pesticide recoveries. Dispersive SPE with different sorbents was also investigated to minimize matrix coextractives and interferences. For analysis, a new automated DSI device was tested in GC-MS to avoid nonvolatile coextractives from contaminating the instrument. LC-MS/MS with positive ESI was used for those pesticides that were difficult to detect by GC-MS. The final method was validated for olives in terms of recoveries, repeatabilities, and reproducibilities using both detection techniques. The results demonstrated that the method achieved acceptable quantitative recoveries of 70-109% with RSDs < 20% for DSI-GC-MS and 88-130% with RSDs < 10% for LC-MS/MS, and LOQ at or below the regulatory maximum residue limits for the pesticides were achieved.

Diethylstilbestrol in fish tissue determined through subcritical fluid extraction and with GC-MS

NASA Astrophysics Data System (ADS)

Qiao, Qinghui; Shi, Nianrong; Feng, Xiaomei; Lu, Jie; Han, Yuqian; Xue, Changhu

2016-06-01

As the key point in sex hormone analysis, sample pre-treatment technology has attracted scientists' attention all over the world, and the development trend of sample preparation forwarded to faster and more efficient technologies. Taking economic and environmental concerns into account, subcritical fluid extraction as a faster and more efficient method has stood out as a sample pre-treatment technology. This new extraction technology can overcome the shortcomings of supercritical fluid and achieve higher extraction efficiency at relatively low pressures and temperatures. In this experiment, a simple, sensitive and efficient method has been developed for the determination of diethylstilbestrol (DES) in fish tissue using subcritical 1,1,1,2-tetrafluoroethane (R134a) extraction in combination with gas chromatography-mass spectrometry (GC-MS). After extraction, freezing-lipid filtration was utilized to remove fatty co-extract. Further purification steps were performed with C18 and NH2 solid phase extraction (SPE). Finally, the analyte was derived by heptafluorobutyric anhydride (HFBA), followed by GC-MS analysis. Response surface methodology (RSM) was employed to optimizing the extraction condition, and the optimized was as follows: extraction pressure, 4.3 MPa; extraction temperature, 26°C; amount of co-solvent volume, 4.7 mL. Under this condition, at a spiked level of 1, 5, 10 μg kg-1, the mean recovery of DES was more than 90% with relative standard deviations (RSDs) less than 10%. Finally, the developed method has been successfully used to analyzing the real samples.

Analysis of mixtures of fatty acids and fatty alcohols in fermentation broth.

PubMed

Liu, Yilan; Chen, Ting; Yang, Maohua; Wang, Caixia; Huo, Weiyan; Yan, Daojiang; Chen, Jinjin; Zhou, Jiemin; Xing, Jianmin

2014-01-03

Microbial production of fatty acids and fatty alcohols has attracted increasing concerns because of energy crisis and environmental impact of fossil fuels. Therefore, simple and efficient methods for the extraction and quantification of these compounds become necessary. In this study, a high-performance liquid chromatography-refractive index detection (HPLC-RID) method was developed for the simultaneous quantification of fatty acids and fatty alcohols in these samples. The optimum chromatographic conditions are C18 column eluted with methanol:water:acetic acid (90:9.9:0.1, v/v/v); column temperature, 26°C; flow rate, 1.0mL/min. Calibration curves of all selected analytes showed good linearity (r(2)≥0.9989). The intra-day and inter-day relative standard deviations (RSDs) of the 10 compounds were less than 4.46% and 5.38%, respectively, which indicated that the method had good repeatability and precision. Besides, a method for simultaneous extraction of fatty acids and fatty alcohols from fermentation broth was optimized by orthogonal design. The optimal extraction conditions were as follows: solvent, ethyl acetate; solvent to sample ratio, 0.5:1; rotation speed, 2min at 260rpm; extraction temperature, 10°C. This study provides simple and fast methods to simultaneously extract and quantify fatty acids and fatty alcohols for the first time. It will be useful for the study of microbial production of these products. Copyright © 2013 Elsevier B.V. All rights reserved.

Capillary electrophoresis with contactless conductivity detection for the quantification of fluoride in lithium ion battery electrolytes and in ionic liquids-A comparison to the results gained with a fluoride ion-selective electrode.

PubMed

Pyschik, Marcelina; Klein-Hitpaß, Marcel; Girod, Sabrina; Winter, Martin; Nowak, Sascha

2017-02-01

In this study, an optimized method using capillary electrophoresis (CE) with a direct contactless conductivity detector (C 4 D) for a new application field is presented for the quantification of fluoride in common used lithium ion battery (LIB) electrolyte using LiPF 6 in organic carbonate solvents and in ionic liquids (ILs) after contacted to Li metal. The method development for finding the right buffer and the suitable CE conditions for the quantification of fluoride was investigated. The results of the concentration of fluoride in different LIB electrolyte samples were compared to the results from the ion-selective electrode (ISE). The relative standard deviations (RSDs) and recovery rates for fluoride were obtained with a very high accuracy in both methods. The results of the fluoride concentration in the LIB electrolytes were in very good agreement for both methods. In addition, the limit of detection (LOD) and limit of quantification (LOQ) values were determined for the CE method. The CE method has been applied also for the quantification of fluoride in ILs. In the fresh IL sample, the concentration of fluoride was under the LOD. Another sample of the IL mixed with Li metal has been investigated as well. It was possible to quantify the fluoride concentration in this sample. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

One-Step Extraction and Hydrolysis of Flavonoid Glycosides in Rape Bee Pollen Based on Soxhlet-Assisted Matrix Solid Phase Dispersion.

PubMed

Tu, Xijuan; Ma, Shuangqin; Gao, Zhaosheng; Wang, Jing; Huang, Shaokang; Chen, Wenbin

2017-11-01

Flavonoids are frequently found as glycosylated derivatives in plant materials. To determine contents of flavonoid aglycones in these matrices, procedures for the extraction and hydrolysis of flavonoid glycosides are required. The current sample preparation method is both labour and time consuming. Develop a modified matrix solid phase dispersion (MSPD) procedure as an alternative methodology for the one-step extraction and hydrolysis of flavonoid glycosides. HPLC-DAD was applied for demonstrating the one-step extraction and hydrolysis of flavonoids in rape bee pollen. The obtained contents of flavonoid aglycones (quercetin, kaempferol, isorhamnetin) were used for the optimisation and validation of the method. The extraction and hydrolysis were accomplished in one step. The procedure completes in 2 h with silica gel as dispersant, a 1:2 ratio of sample to dispersant, and 60% aqueous ethanol with 0.3 M hydrochloric acid as the extraction solution. The relative standard deviations (RSDs) of repeatability were less than 5%, and the recoveries at two fortified levels were between 88.3 and 104.8%. The proposed methodology is simple and highly efficient, with good repeatability and recovery. Compared with currently available methods, the present work has advantages of using less time and labour, higher extraction efficiency, and less consumption of the acid catalyst. This method may have applications for the one-step extraction and hydrolysis of bioactive compounds from plant materials. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

[Analysis of phthalates in plastic food-packaging bags by thin layer chromatography].

PubMed

Chen, Hui; Wang, Yuan; Zhu, Ruohua

2006-01-01

The method for simultaneous determination of four phthalates, namely dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP) and di (2-ethylhexyl) phthalate (DEHP) in plastic food-packaging bags by thin layer chromatography (TLC) was developed. The plastic food-packaging bags were extracted with ethanol by ultrasonication, then the mixture was filtrated through membrane (0.45 microm). The mixture of ethyl acetate-anhydrous ether-isooctane (1 : 4 : 15, v/v) was used as developing agent on the TLC silica gel plate for development. The filtered liquid was spotted on the TLC plate dealt by acetone, and detected with scanning wavelength of 275 nm and reference wavelength of 340 nm. The qualitative analysis of the phthalates was performed using the R(f) values of the chromatogram. The quantitative analysis was performed with external standard method. Good linearities were obtained for DMP, DEP, DBP and DEHP. The detection limits were 2.1 ng for DMP, 2.4 ng for DEP, 3.4 ng for DBP and 4.0 ng for DEHP. The relative standard deviations (RSDs) of the four phthalates were 2.8% - 3.5%. The recoveries of the four phthalate standards in real sample were 78.58% - 111.04%. The method presented has the advantages of high precision, high sensitivity, small sample size, and simple pretreatment . The method was used to detect the four phthalates in the food-packaging bags. The contents in real samples were close to the results by gas chromatography.

Rapid determination of 54 pharmaceutical and personal care products in fish samples using microwave-assisted extraction-Hollow fiber-Liquid/solid phase microextraction.

PubMed

Zhang, Yi; Guo, Wen; Yue, Zhenfeng; Lin, Li; Zhao, Fengjuan; Chen, Peijin; Wu, Weidong; Zhu, Hong; Yang, Bo; Kuang, Yanyun; Wang, Jiong

2017-04-15

In this paper, a simple, rapid, solvent-less and environmental friendliness microextraction method, microwave-assisted extraction-hollow fiber-liquid/solid phase microextraction (MAE-HF-L/SME), was developed for simultaneous extraction and enrichment of 54 trace hydrophilic/lipophilic pharmaceutical and personal care products (PPCPs) from fish samples. A solid-phase extraction material, solid-phase microextraction (SPME) fiber, was synthesized. The SPME fiber had a homogeneous, loose structure and good mechanical properties, and they exhibited a good adsorption capacity for most PPCPs selected. The material formed the basis for the method of MAE-HF-L/SME. A method of liquid chromatography-high resolution mass spectroscopy (LC-HRMS) for analysis of 54 PPCPs. Under optimal synthesis and extraction conditions, the limits of detection (LODs, n=3) and the limits of quantitation (LOQs, n=10) for the 54 PPCPs were between 0.01-0.50μg·kg -1 and 0.052.00μg·kg -1 , respectively. Percent recoveries and the relative standard deviations (RSDs) in spiked fish samples (n=6) were between 56.3%-119.9% and 0.3%-17.1%, respectively. The microextraction process of 54 PPCPs in MAE-HF-L/SME took approximately 12min. The method has a low matrix interference and high enrichment factor and may be applicable for determination of 54 different PPCPs in fish samples. Copyright © 2017 Elsevier B.V. All rights reserved.

[Simultaneous determination of principal components and related substances of raw material drug of ammonium glycyrrhizinate by reversed-phase high performance liquid chromatography].

PubMed

Zhao, Yanyan; Liu, Liyan; Han, Yuanyuan; Li, Yueqiu; Wang, Yan; Shi, Minjian

2013-09-01

An analytical method for the simultaneous determination of 18alpha-glycyrrhizic acid, 18beta-glycyrrhizinic acid, related substances A and B and drug quality standard by reversed-phase high performance liquid chromatography (RP-HPLC) was established. The assay was carried out on a Durashell-C18 column (250 mm x 4.6 mm, 5 microm) with 10 mmol/L ammonium perchlorate (the pH value was adjusted to 8.20 with ammonia)-methanol (48:52, v/v) as mobile phase at a flow rate of 0.80 mL/min, and the detection wavelength was set at 254 nm. The column temperature was 50 degrees C and the injection volume was 10 microL. Under the separation conditions, the calibration curves of the analytes showed good linearities within the mass concentrations of 0.50 -100 mg/L (r > 0.999 9). The detection limits for 18alpha-glycyrrhizic acid, 18beta-glycyrrhizinic acid, related substances A and B were 0.15, 0.10, 0.10, 0.15 mg/L, respectively. The average recoveries were between 97.32% and 99.33% (n = 3) with the relative standard deviations (RSDs) between 0.05% and 1.06%. The method is sensitive, reproducible, and the results are accurate and reliable. The method can be used for the determination of principal components and related substances of ammonium glycyrrhizinate for the quality control of raw material drug of ammonium glycyrrhizinate.

SU-F-J-43: Positional Variation of Implanted Fiducial Markers Over the Course of Image Guided Radiotherapy for Pancreatic Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, S; Jacob, R; Popple, R

2016-06-15

Purpose: Pancreas is a soft-tissue organ, implanted fiducials can change positions due to migration or tissue deformation. This study quantified positional variation of fiducials in IGRT for pancreatic cancer. Methods: 20 patients had at least 3 gold fiducials implanted in pancreas under EUS guidance. Patients had 4D-CT simulation for gated treatment. Daily gated OBI kV images (Turebeam) were used for positional alignment with fiducials for total of 25 or 28 fractions. Relative distances among 3 fiducials (d{sub 1–} {sub 2}, d{sub 1–3}, d{sub 2–3}) were measured from 4D-CT end-of-expiration phase bin; and from gated kV images in first, mid, andmore » last fraction (n=180). Results: The median duration between implant and simulation was 11 (range 0–41) days. The median duration between simulation and first fraction was 17 (range 8–24) days. The median relative distance was 12 (range 4–78) mm for d{sub 1–2}, 24 (range 6–80) mm for d{sub 1–3}, and 19 (range 5–63) mm for d{sub 2–3}. The median deviation was 1 mm for d{sub 1–2}, d{sub 1–3}, d{sub 2–3} between simulation and first fraction, first and mid fraction, mid and last fraction (n=180). Two patients (10%) had deviation >= 5 mm (5, 11 mm) between simulation and first fraction. One patient (5%) had deviation >= 5 mm (11 mm) between first and mid fraction. No patient (0%) had deviation >= 5 mm between mid and last fraction. In all 3 cases with deviation >=5 mm, only one fiducial was significantly deviated. No clear evidence that deviation size was associated with time interval between implant and first fraction. Conclusion: Implanted gold fiducials were quite stable over time in their relative positions in pancreas. Our data suggested at least 3 fiducials are needed. In cases that one fiducial was significantly deviated in daily kV images, this fiducial should be excluded in image guidance.« less

Effects of expected-value information and display format on recognition of aircraft subsystem abnormalities

NASA Technical Reports Server (NTRS)

Palmer, Michael T.; Abbott, Kathy H.

1994-01-01

This study identifies improved methods to present system parameter information for detecting abnormal conditions and to identify system status. Two workstation experiments were conducted. The first experiment determined if including expected-value-range information in traditional parameter display formats affected subject performance. The second experiment determined if using a nontraditional parameter display format, which presented relative deviation from expected value, was better than traditional formats with expected-value ranges included. The inclusion of expected-value-range information onto traditional parameter formats was found to have essentially no effect. However, subjective results indicated support for including this information. The nontraditional column deviation parameter display format resulted in significantly fewer errors compared with traditional formats with expected-value-ranges included. In addition, error rates for the column deviation parameter display format remained stable as the scenario complexity increased, whereas error rates for the traditional parameter display formats with expected-value ranges increased. Subjective results also indicated that the subjects preferred this new format and thought that their performance was better with it. The column deviation parameter display format is recommended for display applications that require rapid recognition of out-of-tolerance conditions, especially for a large number of parameters.

Multivariate optimization of an analytical method for the analysis of dog and cat foods by ICP OES.

PubMed

da Costa, Silvânio Silvério Lopes; Pereira, Ana Cristina Lima; Passos, Elisangela Andrade; Alves, José do Patrocínio Hora; Garcia, Carlos Alexandre Borges; Araujo, Rennan Geovanny Oliveira

2013-04-15

Experimental design methodology was used to optimize an analytical method for determination of the mineral element composition (Al, Ca, Cd, Cr, Cu, Ba, Fe, K, Mg, Mn, P, S, Sr and Zn) of dog and cat foods. Two-level full factorial design was applied to define the optimal proportions of the reagents used for microwave-assisted sample digestion (2.0 mol L(-1) HNO3 and 6% m/v H2O2). A three-level factorial design for two variables was used to optimize the operational conditions of the inductively coupled plasma optical emission spectrometer, employed for analysis of the extracts. A radiofrequency power of 1.2 kW and a nebulizer argon flow of 1.0 L min(-1) were selected. The limits of quantification (LOQ) were between 0.03 μg g(-1) (Cr, 267.716 nm) and 87 μg g(-1) (Ca, 373.690 nm). The trueness of the optimized method was evaluated by analysis of five certified reference materials (CRMs): wheat flour (NIST 1567a), bovine liver (NIST 1577), peach leaves (NIST 1547), oyster tissue (NIST 1566b), and fish protein (DORM-3). The recovery values obtained for the CRMs were between 80 ± 4% (Cr) and 117 ± 5% (Cd), with relative standard deviations (RSDs) better than 5%, demonstrating that the proposed method offered good trueness and precision. Ten samples of pet food (five each of cat and dog food) were acquired at supermarkets in Aracaju city (Sergipe State, Brazil). Concentrations in the dog food ranged between 7.1 mg kg(-1) (Ba) and 2.7 g kg(-1) (Ca), while for cat food the values were between 3.7 mg kg(-1) (Ba) and 3.0 g kg(-1) (Ca). The concentrations of Ca, K, Mg, P, Cu, Fe, Mn, and Zn in the food were compared with the guidelines of the United States' Association of American Feed Control Officials (AAFCO) and the Brazilian Ministry of Agriculture, Livestock, and Food Supply (Ministério da Agricultura, Pecuária e Abastecimento-MAPA). Copyright © 2013 Elsevier B.V. All rights reserved.

Dissolvable layered double hydroxide as an efficient nanosorbent for centrifugeless air-agitated dispersive solid-phase extraction of potentially toxic metal ions from bio-fluid samples.

PubMed

Rajabi, Maryam; Arghavani-Beydokhti, Somayeh; Barfi, Behruz; Asghari, Alireza

2017-03-08

In the present work, a novel nanosorbent namely layered double hydroxides with 4-amino-5-hydroxyl-2,7-naphthalendisulfonic acid monosodium salt interlayer anion (Mg-Al-AHNDA-LDH) was synthesized and applied as a dissolvable nanosorbent in a centrifugeless ultrasound-enhanced air-agitated dispersive solid-phase extraction (USE-AA-D-SPE) method. This method was used for the separation and preconcentration of some metal ions including Cd 2+ , Cr 6+ , Pb 2+ , Co 2+ , and Ni 2+ prior to their determination using the micro-sampling flame atomic absorption spectrometry (MS-FAAS) technique. The most interesting aspect of this nanosorbent is its immediate dissolvability at pH values lower than 4. This capability drastically eliminates the elution step, leading to a great improvement in the extraction efficiency and a decrease in the extraction time. Also in this method, the use of a syringe nanofilter eliminates the need for the centrifugation step, which is time-consuming and essentially causes the analysis to be off-line. Several effective parameters governing the extraction efficiency including the sample solution pH, amount of nanosorbent, eluent condition, number of air-agitation cycles, and sonication time were investigated and optimized. Under the optimized conditions, the good linear dynamic ranges of 2-70, 6-360, 7-725, 7-370, and 8-450 ng mL -1 for the Cd 2+ , Cr 6+ , Pb 2+ , Co 2+ and Ni 2+ ions, respectively, with the correlation of determinations (R 2 s) higher than 0.997 were obtained. The limits of detection (LODs) were found to be 0.6, 1.7, 2.0, 2.1, and 2.4 for the Cd 2+ , Cr 6+ , Pb 2+ , Co 2+ , and Ni 2+ ions, respectively. The intra-day and inter-day precisions (percent relative standard deviations (%RSDs) (n = 5)) were below 7.8%. The proposed method was also successfully applied for the extraction and determination of the target ions in different biological fluid and tap water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of plant growth regulators in pears by microwave-assisted extraction and liquid chromatography with electrospray ionization mass spectrometry.

PubMed

Mao, Xuejin; Tang, Lijuan; Tan, Ting; Wan, Yiqun

2014-06-01

A new method for the determination of six plant growth regulators, 3-indolylacetic acid, 3-indolepropionic acid, 2-naphthoxyacetic acid, 2,4-dicholrophenoxyacetic acid, 1-naphthlcetic acid, and methyl naphthalene-1-acetate, in pears was established by liquid chromatography with electrospray ionization mass spectrometry. In this study, a microwave-assisted extraction technique was first applied for the determination of plant growth regulators in fruit and three cleanup techniques were, respectively, investigated for the purification of pear samples. The chromatographic separation was performed on a Diamonsil C18 column by using 0.01 mol/L formic acid/ammonium formate buffer solution (pH 3.5)/methanol (35:65, v/v) as the mobile phase with a flow rate of 0.7 mL/min in 1:1 split mode. The LODs ranged from 0.3 to 1.9 μg/kg. Under optimized conditions, the average recoveries (five replicates) for six plant growth regulators (spiked at 0.01, 0.05, and 0.5 mg/kg) ranged from 78.9 to 118.0%, and the RSDs were 1.4-10.3%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fluorometric aptamer based assay for ochratoxin A based on the use of exonuclease III.

PubMed

Liu, Renjie; Wu, Hua; Lv, Lei; Kang, Xiaojiao; Cui, Chengbi; Feng, Jin; Guo, Zhijun

2018-04-14

This study describes an aptamer based assay for the mycotoxin ochratoxin A (OTA). The method is based on the use of an OTA-specific aptamer, exonuclease (Exo) III, SYBR Gold as a fluorescent probe, and a complementary strand that specifically combines with the aptamer. In the presence of OTA, the aptamer and OTA hybridize, thereby resulting in the formation of ssDNA, which is not digested by Exo III. Intense fluorescence is observed after addition of SYBR Gold (best measured at excitation/emission wavelengths of 495/540 nm). Fluorescence increases linearly with the log of the OTA concentration in the range from 8 to 1000 ng·mL -1 . The detection limit is 4.7 ng·mL -1 . The assay was applied to the determination of OTA in diluted [2%(v/v)] red wine, and recoveries and RSDs ranged between 93.5% and 113.8%, and between 3.2% and 5.7%, respectively. Graphical abstract In the presence of ochratoxin A (OTA), specific combinations of aptamer and OTA may occur and result in DNA double strands being untied, which avoids being digested by Exo III. Intense fluorescence is observed after SYBR Gold addition.

Determination of phthalate esters in cleaning and personal care products by dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry.

PubMed

Viñas, Pilar; Campillo, Natalia; Pastor-Belda, Marta; Oller, Ainhoa; Hernández-Córdoba, Manuel

2015-01-09

Phthalic acid esters (PEs) were preconcentrated from cleaning products, detergents and cosmetics using ultrasound assisted extraction (UAE) in the presence of acetonitrile, and then submitted to dispersive liquid-liquid microextraction (DLLME). For DLLME, 3mL of acetonitrile extract, 150μL carbon tetrachloride and 10mL aqueous solution were used. The enriched organic phase was evaporated, reconstituted with 25μL acetonitrile and injected into a liquid chromatograph with a mobile phase (acetonitrile:10mM ammonium acetate, pH 4) under gradient elution. Detection was carried out using both diode-array (DAD) and electrospray-ion trap-tandem mass spectrometry (ESI-IT-MS/MS) in the multiple reaction monitoring mode (MRM) of the positive fragment ions. Quantification was carried out using matrix-matched standards. Detection limits were in the range 0.04-0.45ngmL(-1) for the six PEs considered. The recoveries obtained were in the 84-124% range, with RSDs lower than 10%. Thirty three different cleaning products were analyzed. The most frequently found compound was diethyl phthalate. Copyright © 2014 Elsevier B.V. All rights reserved.

Analysis of chlorophenoxy acid herbicides in water by large-volume on-line derivatization and gas chromatography-mass spectrometry.

PubMed

Ding, W H; Liu, C H; Yeh, S P

2000-10-27

This work presents a modified method to analyze chlorophenoxy acid herbicides in water samples. The herbicides 2,4-D (2,4-dichlorophenoxyacetic acid). Silvex (2,4,5-trichlorophenoxypropionic acid) and 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) were used to evaluate the method. The method involves extraction of samples by a graphitized carbon black cartridge, and on-line derivatization in the GC injection port using a large-volume (10-20 microl) direct sample introduction (DSI) device with tetraalkylammonium salts. The analytes were then identified and quantitated by ion-trap gas chromatography-mass spectrometry. The large-volume DSI injection-port derivatization technique provides sensitivity, fast and reproducible results for chlorophenoxy acid herbicides residues, to quantitation at 0.1 to 0.2 microg/l in 500-ml water samples. An enhanced characteristic mass chromatogram of molecular ions of butylated chlorophenoxy acid herbicides with a significant chlorine isotope pattern by electron impact ionization MS allows us to determine herbicides residues at trace levels in aqueous samples. Recovery of the herbicide residues in spiked various water samples ranged from 70 to 99% while RSDs ranged from 1 to 13%.

40 CFR 89.322 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2011 CFR

2011-07-01

... engineering practice. For each range calibrated, if the deviation from a least-squares best-fit straight line... range. If the deviation exceeds these limits, the best-fit non-linear equation which represents the data... interference, system check, and calibration test procedures specified in 40 CFR part 1065 may be used in lieu...

40 CFR 89.322 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2013 CFR

2013-07-01

... engineering practice. For each range calibrated, if the deviation from a least-squares best-fit straight line... range. If the deviation exceeds these limits, the best-fit non-linear equation which represents the data... interference, system check, and calibration test procedures specified in 40 CFR part 1065 may be used in lieu...

40 CFR 89.322 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2014 CFR

2014-07-01

... engineering practice. For each range calibrated, if the deviation from a least-squares best-fit straight line... range. If the deviation exceeds these limits, the best-fit non-linear equation which represents the data... interference, system check, and calibration test procedures specified in 40 CFR part 1065 may be used in lieu...

40 CFR 89.322 - Carbon dioxide analyzer calibration.

Code of Federal Regulations, 2012 CFR

2012-07-01

... engineering practice. For each range calibrated, if the deviation from a least-squares best-fit straight line... range. If the deviation exceeds these limits, the best-fit non-linear equation which represents the data... interference, system check, and calibration test procedures specified in 40 CFR part 1065 may be used in lieu...

Estimation of lamb carcass composition from measurements of the speed of ultrasound in the soft tissues of live animals and carcasses.

PubMed

Miles, C A; Fursey, G A; Fisher, A V; Page, S J

1991-01-01

The application of the velocity of sound (VOS) technique to lamb carcasses in a previous study (Fisher & Page, 1986) measured composition at a hind limb and neck site but was not as precise as fat scores in predicting lean proportion. This study examines VOS measurements made at sites in the hind limbs and along the vertebral column in live sheep and carcasses. A group (A) comprising five breeds of males and females (n = 61) and a sub-group (B) of Scottish Blackface castrated males (n = 34) were studied, and the reciprocal velocity of ultrasound (RV) was measured on the live sheep immediately behind the shoulder and over the last rib using a fixed-distance transducer assembly operating at 5 MHz, and in the hind limbs at 2·25 MHz using the apparatus described by Miles et al. (1984). Corresponding measurements were made on the carcasses which were classified by a Meat and Livestock Commission fatstock officer and then dissected. Standard deviations of lean proportion were 4·48% (A) and 3·39% (B). The residual standard deviations (rsds) for groups A and B respectively were obtained using the following predictors: live mass (LM) 4·27% and 2·96%; LM + breed (B) 3·08% (group A only); LM + mean RV 2·36% and 2·07%; LM + B + mean RV 1·99% (group A only). Using carcass measurements: carcass mass (CM) 4·25% and 2·90%; CM + MLC fat score 2·99% and 2·12%; CM + RV last rib 2·89% and 2·02%. These data show that VOS measurements through dorsal sites of live sheep provide encouragingly precise estimates of carcass lean proportion. For carcasses, dorsal sites provide a less precise estimate of carcass lean but when carcass mass is included in multiple regression the precision of the correlation is comparable with that of multiple regression of fat score with carcass mass. Copyright © 1991. Published by Elsevier Ltd.

Determination of patulin in apple and derived products by UHPLC-MS/MS. Study of matrix effects with atmospheric pressure ionisation sources.

PubMed

Beltrán, Eduardo; Ibáñez, María; Sancho, Juan Vicente; Hernández, Félix

2014-01-01

Sensitive and reliable analytical methodology has been developed for the measurement of patulin in regulated foodstuffs by using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) with triple quadrupole analyser. Solid samples were extracted with ethyl acetate, while liquid samples were directly injected into the chromatographic system after dilution and filtration without any clean-up step. Chromatographic separation was achieved in less than 4min. Electrospray (ESI) and atmospheric pressure chemical ionisation (APCI) sources were evaluated, in order to assess matrix effects. The use of ESI source caused strong signal suppression in samples; however, matrix effect was negligible using APCI, allowing quantification with calibration standards prepared in solvent. The method was validated in four different apple matrices (juice, fruit, puree and compote) at two concentrations at the low μgkg(-1) level. Average recoveries (n=5) ranged from 71% to 108%, with RSDs lower than 14%. Copyright © 2013 Elsevier Ltd. All rights reserved.

Validation of an Analytical Method for the Determination of Pesticide Residues in Vine Leaves by GC-MS/MS.

PubMed

Maestroni, Britt; Abu Alnaser, Amer; Ghanem, Iyad; Islam, Marivil; Cesio, Veronica; Heinzen, Horacio; Kelly, Simon; Cannavan, Andrew

2018-06-27

A modified and miniaturized SweEt/QuEChERS method for pesticide residue analysis applied to vine leaves is presented. The deep-frozen plant material was cryogenically processed. A 2 g analytical portion was hydrated for 30 min and extracted with acidified ethyl acetate after buffering with NaHCO 3 and adding Na 2 SO 4 . A dispersive solid-phase (d-SPE) cleanup step with primary-secondary amine (PSA) was performed. The pesticide residues were determined using GC-MS/MS. The whole procedure was validated for 54-59 pesticides at 0.01, 0.02, 0.1, and 0.2 mg/kg in fresh vine leaves ( Vitis vinifera). The key method performance parameters investigated were specificity, linearity, trueness, within laboratory repeatability and reproducibility, limit of detection, limit of quantitation, and matrix effects. Recoveries for the 59 pesticides tested ranged from 60 to 110%, and the RSDs were lower than 20% for the majority of the pesticides studied.

Acrylamide levels in Finnish foodstuffs analysed with liquid chromatography tandem mass spectrometry.

PubMed

Eerola, Susanna; Hollebekkers, Koen; Hallikainen, Anja; Peltonen, Kimmo

2007-02-01

Sample clean-up and HPLC with tandem mass spectrometric detection (LC-MS/MS) was validated for the routine analysis of acrylamide in various foodstuffs. The method used proved to be reliable and the detection limit for routine monitoring was sensitive enough for foods and drinks (38 microg/kg for foods and 5 microg/L for drinks). The RSDs for repeatability and day-to-day variation were below 15% in all food matrices. Two hundred and one samples which included more than 30 different types of food and foods manufactured and prepared in various ways were analysed. The main types of food analysed were potato and cereal-based foods, processed foods (pizza, minced beef meat, meat balls, chicken nuggets, potato-ham casserole and fried bacon) and coffee. Acrylamide was detected at levels, ranging from nondetectable to 1480 microg/kg level in solid food, with crisp bread exhibiting the highest levels. In drinks, the highest value (29 microg/L) was found in regular coffee drinks.

[Determination of arsenic speciation in Scomberomorus niphonius by capillary electrophoresis-inductively coupled plasma mass spectrometry].

PubMed

Chen, Fa-rong; Zheng, Li; Wang, Zhi-Guang; Sun, Jie; Han, Li-Hui; Wang, Xiao-ru

2014-06-01

A method for the detection of arsenocholine (AsC), arsenobetaine (AsB), As(III), dimethylarsinic (DMA), monomethylarsonic (MMA) and As (V) by capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) was established. The results showed that the six species of arsenic were separated within 20 min under the optimized conditions. Good linearities of 6 arsenic species were observed in the range from 2 to 50 μg x L(-1) with the linear correlation greater than 0.996, the detection limits were 0.10-1.08 μg x L(-1) and the RSDs (n = 5) of the peak areas were smaller than 7%. The method was successfully adopted to the determination of the species in Scomberomorus niphonius. The recoveries were between 93% and 98%, and we found the arsenobetaine (AsB) was the main species in the sample. The method was suitable for the analysis of other biological samples with the advantages of good stability, less sample consumption, short analysis time and convenience.

Assay of picogram level isocarbophos residue on tangerines and oranges with luminol-albumin chemiluminescence system.

PubMed

Chen, Donghua; Song, Zhenghua; Lv, Hairu

2012-12-15

A sensitive flow injection-chemiluminescence (FI-CL) method for the determination of isocarbophos (ICP) residue on tangerines and oranges was proposed. It was found that the CL intensity from luminol-albumin CL reaction could be obviously quenched in the presence of ICP and the decrease in CL intensity was proportional to the logarithm of ICP concentrations ranging from 1.0 to 1000 pmol L(-1), giving the limit of detection of 0.3 pmol L(-1) (3σ). The proposed procedure was successfully applied to the determination of ICP residue on tangerines and oranges with recoveries varying from 92.0 to 111.0% and RSDs less than 5.0%. The possible CL mechanism of luminol-albumin-ICP reaction was discussed, and ICP to albumin's binding constant (K(D)=1.00 × 10(6) L mol(-1)) and the number of binding sites (n=1.00) were given by the homemade FI-CL model. Copyright © 2012 Elsevier Ltd. All rights reserved.

Longitudinal and Cross-Sectional Analyses of Visual Field Progression in Participants of the Ocular Hypertension Treatment Study (OHTS)

PubMed Central

Chauhan, Balwantray C; Keltner, John L; Cello, Kim E; Johnson, Chris A; Anderson, Douglas R; Gordon, Mae O; Kass, Michael A

2014-01-01

Purpose Visual field progression can be determined by evaluating the visual field by serial examinations (longitudinal analysis), or by a change in classification derived from comparison to age-matched normal data in single examinations (cross-sectional analysis). We determined the agreement between these two approaches in data from the Ocular Hypertension Treatment Study (OHTS). Methods Visual field data from 3088 eyes of 1570 OHTS participants (median follow-up 7 yrs, 15 tests with static automated perimetry) were analysed. Longitudinal analyses were performed with change probability with total and pattern deviation, and cross-sectional analysis with Glaucoma Hemifield Test, Corrected Pattern Standard Deviation, and Mean Deviation. The rates of Mean Deviation and General Height change were compared to estimate the degree of diffuse loss in emerging glaucoma. Results The agreement on progression in longitudinal and cross-sectional analyses ranged from 50% to 61% and remained nearly constant across a wide range of criteria. In contrast, the agreement on absence of progression ranged from 97% to 99.7%, being highest for the stricter criteria. Analyses of pattern deviation were more conservative than total deviation, with a 3 to 5 times lesser incidence of progression. Most participants developing field loss had both diffuse and focal change. Conclusions Despite considerable overall agreement, between 40 to 50% of eyes identified as having progressed with either longitudinal or cross-sectional analyses were identified with only one of the analyses. Because diffuse change is part of early glaucomatous damage, pattern deviation analyses may underestimate progression in patients with ocular hypertension. PMID:21149774

Preparation of a polymeric ionic liquid-coated solid-phase microextraction fiber by surface radical chain-transfer polymerization with stainless steel wire as support.

PubMed

Feng, Juanjuan; Sun, Min; Xu, Lili; Li, Jubai; Liu, Xia; Jiang, Shengxiang

2011-10-28

Polymeric 1-vinyl-3-octylimidazolium hexafluorophosphate was synthesized in situ on stainless steel wire by surface radical chain-transfer polymerization and used as sensitive coatings in solid-phase microextraction. The outer surface of the stainless steel wire was firstly coated with microstructured silver layer via silver mirror reaction and then functionalized with self-assembled monolayers of 1,8-octanedithiol, which acted as chain transfer agent in the polymerization. Coupled to gas chromatography, extraction performance of the fiber was studied with both headspace and direct-immersion modes using benzene, toluene, ethylbenzene and xylenes (BTEX), phenols and polycyclic aromatic hydrocarbon (PAHs) as model analytes. In combination with the microstructured silver layer, the PIL-coated fiber exhibited high extraction efficiency. Linear ranges for BTEX with headspace mode were in the range of 0.2-1000 μg L(-1) for benzene, and 0.1-1000 μg L(-1) for toluene, ethylbenzene and xylenes. Limits of detection (LODs) were from 0.02 to 0.05 μg L(-1). Wide linear ranges of direct-immersion mode for the extraction of several phenols and PAHs were also obtained with correlation coefficients (R) from 0.9943 to 0.9997. The proposed fiber showed good durability with long lifetime. RSDs of 56 times extraction were still in an acceptable range, from 8.85 to 22.8%. Copyright © 2011 Elsevier B.V. All rights reserved.

Multiwalled carbon nanotubes as solid-phase extraction materials for the gas chromatographic determination of organophosphorus pesticides in waters.

PubMed

Ravelo-Pérez, Lidia M; Hernández-Borges, Javier; Angel Rodríguez-Delgado, Miguel

2008-10-01

In the present work, a GC method with nitrogen-phosphorus detection (NPD) was developed for the simultaneous determination of eight organophosphorus pesticide (OPP) residues (i.e., ethoprofos, diazinon, chlorpyrifos-methyl, fenitrothion, malathion, chlorpyrifos, fenamiphos, and buprofezin) in water samples. Preconcentration of the water samples was carried out using an SPE procedure with multiwalled carbon nanotubes (MWCNTs) of 10-15 nm od, 2-6 nm id, and 0.1-10 microm length as stationary phase. Extraction parameters, such as the amount of MWCNTs, sample volume, pH, and type and amount of the eluent were optimized. The most favorable conditions were as follows: 40 mg MWCNTs, 800 mL water, pH 6.0, and 20 mL dichloromethane, respectively. The MWCNTs-SPE-GC-NPD method was applied to the determination of these pesticides in real water samples: mineral and ground water as well as run-off water from an agricultural area collected shortly before opening out onto the sea. A recovery study was developed with five consecutive extractions of the three types of water spiked at three concentration levels (n = 15). Mean recovery values were in the range of 75-116% for mineral water (RSD < 6.3%), 67-119% for ground water (RSD < 5.8%), and 57-81% for run-off waters (RSDs < 6.9%), except for fenamiphos (mean recovery values between 40 and 84% for the three types of waters, RSDs < 8.9%). LODs were in the low ng/L level (i.e., levels below the maximum residue limits (MRLs) established by the European Union (EU) legislation for these compounds in waters). The proposed method was also applied to the analysis of six water samples (two of each type: mineral, ground, and run-off waters) in which no residues of the selected pesticides were found. Results show that the MWCNTs used in this work have a high adsorbability of the pesticides under study. The main advantage of the use of these MWCNTs is their low cost when compared with those MWCNTs previously used in the literature and with conventional SPE cartridges.

Ultra high performance liquid chromatography-time of flight mass spectrometry for analysis of avocado fruit metabolites: method evaluation and applicability to the analysis of ripening degrees.

PubMed

Hurtado-Fernández, Elena; Pacchiarotta, Tiziana; Gómez-Romero, María; Schoenmaker, Bart; Derks, Rico; Deelder, André M; Mayboroda, Oleg A; Carrasco-Pancorbo, Alegría; Fernández-Gutiérrez, Alberto

2011-10-21

We have developed an analytical method using UHPLC-UV/ESI-TOF MS for the comprehensive profiling of the metabolites found in the methanolic extracts of 13 different varieties of avocado at two different ripening degrees. Both chromatographic and detection parameters were optimized in order to maximize the number of compounds detected and the sensitivity. After achieving the optimum conditions, we performed a complete analytical validation of the method with respect to its linearity, sensitivity, precision, accuracy and possible matrix effects. The LODs ranged from 1.64 to 730.54 ppb (in negative polarity) for benzoic acid and chrysin, respectively, whilst they were found within the range from 0.51 to 310.23 ppb in positive polarity. The RSDs for repeatability test did not exceed 7.01% and the accuracy ranged from 97.2% to 102.0%. Our method was then applied to the analysis of real avocado samples and advanced data processing and multivariate statistical analysis (PCA, PLS-DA) were carried out to discriminate/classify the examined avocado varieties. About 200 compounds belonging to various structural classes were tentatively identified; we are certain about the identity of around 60 compounds, 20 of which have been quantified in terms of their own commercially available standard. Copyright © 2011 Elsevier B.V. All rights reserved.

Enrichment of neonicotinoid insecticides from lemon juice sample with magnetic three-dimensional graphene as the adsorbent followed by determination with high-performance liquid chromatography.

PubMed

Liu, Li; Feng, Tao; Wang, Chun; Wu, Qiuhua; Wang, Zhi

2014-06-01

A novel 3D-graphene (3D-G) magnetic nanomaterial was prepared and used as an adsorbent for the extraction of four neonicotinoid insecticides (acetamiprid, imidacloprid, thiacloprid, and thiamethoxam) from lemon juice sample. Then, HPLC with UV detection was applied for the determination of the neonicotinoid insecticides desorbed from the 3D-G magnetic nanomaterial. The main experimental parameters that affect the extraction efficiencies such as the amount of 3D-G magnetic nanomaterial, sample solution pH, extraction time, salting-out effect, and desorption conditions were studied and optimized. As a result, the linear concentration range of the method was from 0.3 to 100.0 ng/mL for thiacloprid, from 0.5 to 100.0 ng/mL for imidacloprid and acetamiprid, and from 1.0 to 100.0 ng/mL for thiamethoxam, with correlation coefficients of 0.9965-0.9985, respectively. The LODs of the method based on an S/N of 3 were between 0.08 and 0.2 ng/mL. The enrichment factors obtained were between 67 and 427, and the RSDs (n = 6) were in the range from 4.6 to 7.1%, and the recoveries of the method fell in the range of 88.75 to 111.60%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A rapid and sensitive analytical method for the determination of 14 pyrethroids in water samples.

PubMed

Feo, M L; Eljarrat, E; Barceló, D

2010-04-09

A simple, efficient and environmentally friendly analytical methodology is proposed for extracting and preconcentrating pyrethroids from water samples prior to gas chromatography-negative ion chemical ionization mass spectrometry (GC-NCI-MS) analysis. Fourteen pyrethroids were selected for this work: bifenthrin, cyfluthrin, lambda-cyhalothrin, cypermethrin, deltamethrin, esfenvalerate, fenvalerate, fenpropathrin, tau-fluvalinate, permethrin, phenothrin, resmethrin, tetramethrin and tralomethrin. The method is based on ultrasound-assisted emulsification-extraction (UAEE) of a water-immiscible solvent in an aqueous medium. Chloroform was used as extraction solvent in the UAEE technique. Target analytes were quantitatively extracted achieving an enrichment factor of 200 when 20 mL aliquot of pure water spiked with pyrethroid standards was extracted. The method was also evaluated with tap water and river water samples. Method detection limits (MDLs) ranged from 0.03 to 35.8 ng L(-1) with RSDs values < or =3-25% (n=5). The coefficients of estimation of the calibration curves obtained following the proposed methodology were > or =0.998. Recovery values were in the range of 45-106%, showing satisfactory robustness of the method for analyzing pyrethroids in water samples. The proposed methodology was applied for the analysis of river water samples. Cypermethrin was detected at concentration levels ranging from 4.94 to 30.5 ng L(-1). Copyright 2010 Elsevier B.V. All rights reserved.

Vortex-assisted magnetic β-cyclodextrin/attapulgite-linked ionic liquid dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the fast determination of four fungicides in water samples.

PubMed

Yang, Miyi; Xi, Xuefei; Wu, Xiaoling; Lu, Runhua; Zhou, Wenfeng; Zhang, Sanbing; Gao, Haixiang

2015-02-13

A novel microextraction technique combining magnetic solid-phase microextraction (MSPME) with ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) to determine four fungicides is presented in this work for the first time. The main factors affecting the extraction efficiency were optimized by the one-factor-at-a-time approach and the impacts of these factors were studied by an orthogonal design. Without tedious clean-up procedure, analytes were extracted from the sample to the adsorbent and organic solvent and then desorbed in acetonitrile prior to chromatographic analysis. Under the optimum conditions, good linearity and high enrichment factors were obtained for all analytes, with correlation coefficients ranging from 0.9998 to 1.0000 and enrichment factors ranging 135 and 159 folds. The recoveries for proposed approach were between 98% and 115%, the limits of detection were between 0.02 and 0.04 μg L(-1) and the RSDs changed from 2.96 to 4.16. The method was successfully applied in the analysis of four fungicides (azoxystrobin, chlorothalonil, cyprodinil and trifloxystrobin) in environmental water samples. The recoveries for the real water samples ranged between 81% and 109%. The procedure proved to be a time-saving, environmentally friendly, and efficient analytical technique. Copyright © 2015 Elsevier B.V. All rights reserved.

Activated carbon adsorption of quinolone antibiotics in water: Performance, mechanism, and modeling.

PubMed

Fu, Hao; Li, Xuebing; Wang, Jun; Lin, Pengfei; Chen, Chao; Zhang, Xiaojian; Suffet, I H Mel

2017-06-01

The extensive use of antibiotics has led to their presence in the aquatic environment, and introduces potential impacts on human and ecological health. The capability of powdered activated carbon (PAC) to remove six frequently used quinolone (QN) antibiotics during water treatment was evaluated to improve drinking water safety. The kinetics of QN adsorption by PAC was best described by a pseudo second-order equation, and the adsorption capacity was well described by the Freundlich isotherm equation. Isotherms measured at different pH showed that hydrophobic interaction, electrostatic interaction, and π-π dispersion force were the main mechanisms for adsorption of QNs by PAC. A pH-dependent isotherm model based on the Freundlich equation was developed to predict the adsorption capacity of QNs by PAC at different pH values. This model had excellent prediction capabilities under different laboratory scenarios. Small relative standard derivations (RSDs), i.e., 0.59%-0.92% for ciprofloxacin and 0.09%-3.89% for enrofloxacin, were observed for equilibrium concentrations above the 0.3mg/L level. The RSDs increased to 11.9% for ciprofloxacin and 32.1% for enrofloxacin at μg/L equilibrium levels, which is still acceptable. This model could be applied to predict the adsorption of other chemicals having different ionized forms. Copyright © 2016. Published by Elsevier B.V.

Large-deviation probabilities for correlated Gaussian processes and intermittent dynamical systems

NASA Astrophysics Data System (ADS)

Massah, Mozhdeh; Nicol, Matthew; Kantz, Holger

2018-05-01

In its classical version, the theory of large deviations makes quantitative statements about the probability of outliers when estimating time averages, if time series data are identically independently distributed. We study large-deviation probabilities (LDPs) for time averages in short- and long-range correlated Gaussian processes and show that long-range correlations lead to subexponential decay of LDPs. A particular deterministic intermittent map can, depending on a control parameter, also generate long-range correlated time series. We illustrate numerically, in agreement with the mathematical literature, that this type of intermittency leads to a power law decay of LDPs. The power law decay holds irrespective of whether the correlation time is finite or infinite, and hence irrespective of whether the central limit theorem applies or not.

Analysis of preservatives with different polarities in beverage samples by dual-phase dual stir bar sorptive extraction combined with high-performance liquid chromatography.

PubMed

Xu, Jin; Chen, Beibei; He, Man; Hu, Bin

2013-02-22

A new concept of "dual-phase dual stir bar sorptive extraction (SBSE)" was proposed to simultaneously extract six preservatives with different polarities (logKo/w values of 1.27-3.41), namely, benzoic acid (BA), sorbic acid (SA), methyl p-hydroxybenzoate (MP), ethyl p-hydroxybenzoate (EP), propyl p-hydroxybenzoate (PP), and butyl p-hydroxybenzoate (BP). The dual-phase dual SBSE apparatus was consisted of two differently coated stir bars, a 3-aminopropyltriethoxysilane (APTES)-hydroxy-terminated silicone oil (OH-TSO)-coated stir bar that was prepared by sol-gel technique and a C(18) silica (C(18))-polydimethylsiloxane (PDMS)-coated stir bar that was prepared by adhesion. In dual-phase dual SBSE, the two stir bars with different coatings were placed in the same sample solution for the simultaneous extraction of the target analytes with different polarities, and then the bars were desorbed in the same desorption solvent. The extraction performance of the dual-phase dual SBSE for the six preservatives was evaluated by comparing with the conventional SBSE (individual stir bar) with different coatings, including commercial PDMS, homemade PDMS, C(18)-APTES-OH-TSO, APTES-OH-TSO, and C(18)-PDMS. The experimental results showed that the dual-phase dual SBSE had the highest extraction efficiency for the six target preservatives. Based on this fact, a novel method by combining the dual-phase dual SBSE which was consisted of the APTES-OH-TSO-coated and C(18)-PDMS-coated stir bars with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was developed for the simultaneous analysis of six target beverage preservatives in beverages. Under optimal conditions, the limits of detection (LODs) for six target preservatives ranged from 0.6 to 2.7 μgL(-1) with the relative standard deviations (RSDs) of 4.6-9.2% (C(BA,SA)=5 μgL(-1),C(MP)=20 μgL(-1),C(EP,PP,BP)=10 μgL(-1), n=7). The enrichment factors (EFs) were approximately 16-42-fold (theoretical EF was 50-fold). The proposed method was validated by the analysis of six target preservatives in three kinds of beverage samples, and the recoveries for the spiked samples were in the range of 76.6-118.6% for cola, 74.6-17.5% for orange juice, and 83.0-119.1% for herbal tea, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

A twin purification/enrichment procedure based on two versatile solid/liquid extracting agents for efficient uptake of ultra-trace levels of lorazepam and clonazepam from complex bio-matrices.

PubMed

Hemmati, Maryam; Rajabi, Maryam; Asghari, Alireza

2017-11-17

In this research work, two consecutive dispersive solid/liquid phase microextractions based on efficient extraction media were developed for the influential and clean pre-concentration of clonazepam and lorazepam from complicated bio-samples. The magnetism nature of the proposed nanoadsorbent proceeded the clean-up step conveniently and swiftly (∼5min), pursued by a further enrichment via a highly effective and rapid emulsification microextraction process (∼4min) based on a deep eutectic solvent (DES). Finally, the instrumental analysis step was practicable via high performance liquid chromatography-ultraviolet detection. The solid phase used was an adequate magnetic nanocomposite termed as polythiophene-sodium dodecyl benzene sulfonate/iron oxide (PTh-DBSNa/Fe 3 O 4 ), easily and cost-effectively prepared by the impressive co-precipitation method followed by the efficient in situ sonochemical oxidative polymerization approach. The identification techniques viz. FESEM, XRD, and EDX certified the supreme physico-chemical properties of this effective nanosorbent. Also the powerful liquid extraction agent, DES, based on bio-degradable choline chloride, possessed a high efficiency, tolerable safety, low cost, and facile and mild synthesis route. The parameters involved in this versatile hyphenated procedure, efficiently evaluated via the central composite design (CCD), showed that the best extraction conditions consisted of an initial pH value of 7.2, 17mg of the PTh-DBSNa/Fe 3 O 4 nanocomposite, 20 air-agitation cycles (first step), 245μL of methanol, 250μL of DES, 440μL of THF, and 8 air-agitation cycles (second step). Under the optimal conditions, the understudied drugs could be accurately determined in the wide linear dynamic ranges (LDRs) of 4.0-3000ngmL -1 and 2.0-2000ngmL -1 for clonazepam and lorazepam, respectively, with low limits of detection (LODs) ranged from 0.7 to 1.0ngmL -1 . The enrichment factor (EF) and percentage extraction recovery (%ER) values were found to be 75 and 57% for clonazepam and 56 and 42% for lorazepam at the spiked level of 75.0ngmL -1 , possessing proper repeatabilities (relative standard deviation values (RSDs) below 5.9%, n=3). These valid analytical features provided quite accurate drug analyses at therapeutically low spans and levels below potentially toxic domains, implying a proper purification/enrichment of the proposed microextraction procedure. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of using the tongue deviation angle as a warning sign of a stroke

PubMed Central

2012-01-01

Background The symptom of tongue deviation is observed in a stroke or transient ischemic attack. Nevertheless, there is much room for the interpretation of the tongue deviation test. The crucial factor is the lack of an effective quantification method of tongue deviation. If we can quantify the features of the tongue deviation and scientifically verify the relationship between the deviation angle and a stroke, the information provided by the tongue will be helpful in recognizing a warning of a stroke. Methods In this study, a quantification method of the tongue deviation angle was proposed for the first time to characterize stroke patients. We captured the tongue images of stroke patients (15 males and 10 females, ranging between 55 and 82 years of age); transient ischemic attack (TIA) patients (16 males and 9 females, ranging between 53 and 79 years of age); and normal subjects (14 males and 11 females, ranging between 52 and 80 years of age) to analyze whether the method is effective. In addition, we used the receiver operating characteristic curve (ROC) for the sensitivity analysis, and determined the threshold value of the tongue deviation angle for the warning sign of a stroke. Results The means and standard deviations of the tongue deviation angles of the stroke, TIA, and normal groups were: 6.9 ± 3.1, 4.9 ± 2.1 and 1.4 ± 0.8 degrees, respectively. Analyzed by the unpaired Student’s t-test, the p-value between the stroke group and the TIA group was 0.015 (>0.01), indicating no significant difference in the tongue deviation angle. The p-values between the stroke group and the normal group, as well as between the TIA group and the normal group were both less than 0.01. These results show the significant differences in the tongue deviation angle between the patient groups (stroke and TIA patients) and the normal group. These results also imply that the tongue deviation angle can effectively identify the patient group (stroke and TIA patients) and the normal group. With respect to the visual examination, 40% and 32% of stroke patients, 24% and 16% of TIA patients, and 4% and 0% of normal subjects were found to have tongue deviations when physicians “A” and “B” examined them. The variation showed the essentiality of the quantification method in a clinical setting. In the receiver operating characteristic curve (ROC), the Area Under Curve (AUC, = 0.96) indicates good discrimination. The tongue deviation angle more than the optimum threshold value (= 3.2°) predicts a risk of stroke. Conclusions In summary, we developed an effective quantification method to characterize the tongue deviation angle, and we confirmed the feasibility of recognizing the tongue deviation angle as an early warning sign of an impending stroke. PMID:22908956

Analysis of using the tongue deviation angle as a warning sign of a stroke.

PubMed

Wei, Ching-Chuan; Huang, Shu-Wen; Hsu, Sheng-Lin; Chen, Hsing-Chung; Chen, Jong-Shin; Liang, Hsinying

2012-08-21

The symptom of tongue deviation is observed in a stroke or transient ischemic attack. Nevertheless, there is much room for the interpretation of the tongue deviation test. The crucial factor is the lack of an effective quantification method of tongue deviation. If we can quantify the features of the tongue deviation and scientifically verify the relationship between the deviation angle and a stroke, the information provided by the tongue will be helpful in recognizing a warning of a stroke. In this study, a quantification method of the tongue deviation angle was proposed for the first time to characterize stroke patients. We captured the tongue images of stroke patients (15 males and 10 females, ranging between 55 and 82 years of age); transient ischemic attack (TIA) patients (16 males and 9 females, ranging between 53 and 79 years of age); and normal subjects (14 males and 11 females, ranging between 52 and 80 years of age) to analyze whether the method is effective. In addition, we used the receiver operating characteristic curve (ROC) for the sensitivity analysis, and determined the threshold value of the tongue deviation angle for the warning sign of a stroke. The means and standard deviations of the tongue deviation angles of the stroke, TIA, and normal groups were: 6.9 ± 3.1, 4.9 ± 2.1 and 1.4 ± 0.8 degrees, respectively. Analyzed by the unpaired Student's t-test, the p-value between the stroke group and the TIA group was 0.015 (>0.01), indicating no significant difference in the tongue deviation angle. The p-values between the stroke group and the normal group, as well as between the TIA group and the normal group were both less than 0.01. These results show the significant differences in the tongue deviation angle between the patient groups (stroke and TIA patients) and the normal group. These results also imply that the tongue deviation angle can effectively identify the patient group (stroke and TIA patients) and the normal group. With respect to the visual examination, 40% and 32% of stroke patients, 24% and 16% of TIA patients, and 4% and 0% of normal subjects were found to have tongue deviations when physicians "A" and "B" examined them. The variation showed the essentiality of the quantification method in a clinical setting. In the receiver operating characteristic curve (ROC), the Area Under Curve (AUC, = 0.96) indicates good discrimination. The tongue deviation angle more than the optimum threshold value (= 3.2°) predicts a risk of stroke. In summary, we developed an effective quantification method to characterize the tongue deviation angle, and we confirmed the feasibility of recognizing the tongue deviation angle as an early warning sign of an impending stroke.

Characterizing Accuracy and Precision of Glucose Sensors and Meters

PubMed Central

2014-01-01

There is need for a method to describe precision and accuracy of glucose measurement as a smooth continuous function of glucose level rather than as a step function for a few discrete ranges of glucose. We propose and illustrate a method to generate a “Glucose Precision Profile” showing absolute relative deviation (ARD) and /or %CV versus glucose level to better characterize measurement errors at any glucose level. We examine the relationship between glucose measured by test and comparator methods using linear regression. We examine bias by plotting deviation = (test – comparator method) versus glucose level. We compute the deviation, absolute deviation (AD), ARD, and standard deviation (SD) for each data pair. We utilize curve smoothing procedures to minimize the effects of random sampling variability to facilitate identification and display of the underlying relationships between ARD or %CV and glucose level. AD, ARD, SD, and %CV display smooth continuous relationships versus glucose level. Estimates of MARD and %CV are subject to relatively large errors in the hypoglycemic range due in part to a markedly nonlinear relationship with glucose level and in part to the limited number of observations in the hypoglycemic range. The curvilinear relationships of ARD and %CV versus glucose level are helpful when characterizing and comparing the precision and accuracy of glucose sensors and meters. PMID:25037194

Large Deviations in Weakly Interacting Boundary Driven Lattice Gases

NASA Astrophysics Data System (ADS)

van Wijland, Frédéric; Rácz, Zoltán

2005-01-01

One-dimensional, boundary-driven lattice gases with local interactions are studied in the weakly interacting limit. The density profiles and the correlation functions are calculated to first order in the interaction strength for zero-range and short-range processes differing only in the specifics of the detailed-balance dynamics. Furthermore, the effective free-energy (large-deviation function) and the integrated current distribution are also found to this order. From the former, we find that the boundary drive generates long-range correlations only for the short-range dynamics while the latter provides support to an additivity principle recently proposed by Bodineau and Derrida.

Quantitation of underivatized branched-chain amino acids in sport nutritional supplements by capillary electrophoresis with direct or indirect UV absorbance detection.

PubMed

Qiu, Jun; Wang, Jinhao; Xu, Zhongqi; Liu, Huiqing; Ren, Jie

2017-01-01

The branched-chain amino acids (BCAAs) including leucine (Leu), isoleucine (Ile) and valine (Val) play a pivotal role in the human body. Herein, we developed capillary electrophoresis (CE) coupled with conventional UV detector to quantify underivatized BCAAs in two kinds of sport nutritional supplements. For direct UV detection at 195 nm, the BCAAs (Leu, two enantiomers of Ile and Val) were separated in a background electrolyte (BGE) consisting of 40.0 mmol/L sodium tetraborate, and 40.0 mmol/L β-cyclodextrin (β-CD) at pH 10.2. In addition, the indirect UV detection at 264 nm was achieved in a BGE of 2.0 mmol/L Na2HPO4, 10.0 mmol/L p-aminosalicylic acid (PAS) as UV absorbing probe, and 40.0 mmol/L β-CD at pH 12.2. The β-CD significantly benefited the isomeric separation of Leu, L- and D-Ile. The optimal conditions allowed the LODs (limit of detections) of direct and indirect UV absorption detection to be tens μmol/L level, which was comparable to the reported CE inline derivatization method. The RSDs (relative standard deviations) of migration time and peak area were less than 0.91% and 3.66% (n = 6). Finally, CE with indirect UV detection method was applied for the quantitation of BCAAs in two commercial sport nutritional supplements, and good recovery and precision were obtained. Such simple CE method without tedious derivatization process is feasible of quality control and efficacy evaluation of the supplemental proteins.

Into the deep: Evaluation of SourceTracker for assessment of faecal contamination of coastal waters.

PubMed

Henry, Rebekah; Schang, Christelle; Coutts, Scott; Kolotelo, Peter; Prosser, Toby; Crosbie, Nick; Grant, Trish; Cottam, Darren; O'Brien, Peter; Deletic, Ana; McCarthy, David

2016-04-15

Faecal contamination of recreational waters is an increasing global health concern. Tracing the source of the contaminant is a vital step towards mitigation and disease prevention. Total 16S rRNA amplicon data for a specific environment (faeces, water, soil) and computational tools such as the Markov-Chain Monte Carlo based SourceTracker can be applied to microbial source tracking (MST) and attribution studies. The current study applied artificial and in-laboratory derived bacterial communities to define the potential and limitations associated with the use of SourceTracker, prior to its application for faecal source tracking at three recreational beaches near Port Phillip Bay (Victoria, Australia). The results demonstrated that at minimum multiple model runs of the SourceTracker modelling tool (i.e. technical replicates) were required to identify potential false positive predictions. The calculation of relative standard deviations (RSDs) for each attributed source improved overall predictive confidence in the results. In general, default parameter settings provided high sensitivity, specificity, accuracy and precision. Application of SourceTracker to recreational beach samples identified treated effluent as major source of human-derived faecal contamination, present in 69% of samples. Site-specific sources, such as raw sewage, stormwater and bacterial populations associated with the Yarra River estuary were also identified. Rainfall and associated sand resuspension at each location correlated with observed human faecal indicators. The results of the optimised SourceTracker analysis suggests that local sources of contamination have the greatest effect on recreational coastal water quality. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Preparation and performance characterization of gold nanoparticles modified chiral capillary electrochromatography stationary phase].

PubMed

Xiong, Lele; Li, Ruijun; Ji, Yibing

2017-07-08

Gold nanoparticles (GNPs, 15 nm) were prepared and introduced to amino groups derived silica monolithic column. Bovine serum albumin (BSA) was immobilized via covalent modification method onto the carboxylic functionalized GNPs to afford chiral stationary phase (CSP) for enantioseparation. GNPs were well dispersed and successfully incorporated onto the columns with the contents as high as 17.18% by characterization method such as transmission electron microscopy (TEM), ultraviolet (UV)-visible absorption spectra and scanning electron microscopy (SEM). The preparation conditions of the BSA modified CSP were optimized and 10% (v/v) 3-aminopropyltriethoxysilane (APTES) and 15 g/L BSA were selected as appropriate reaction conditions. The enantioseparation performance of the BSA modified CSP has been investigated by capillary electrochromatography (CEC). Enantiomers of tryptophan, ephedrine and atenolol were resolved, and the baseline separation of tryptophan was achieved. Meanwhile, the influences of pH value, buffer concentrations and applied voltages used on the chiral separation were studied, and the optimal separation conditions were 10 mmol/L phosphate buffer at pH 7.4 and 15 kV applied voltages. In comparison with the BSA modified CSP prepared by physical adsorption, the CSP prepared by covalent modification method had better separation results, and the analytes could be separated directly without pre-column derivatization. In addition, the prepared BSA modified CSP exhibited good run to run repeatability with relative standard deviations (RSDs) of the migration times and selectivity factors not more than 2.3% and 0.96%, respectively. This work offers a good thinking for modification with other proteins or other types of chiral selectors.

Quantitation of underivatized branched-chain amino acids in sport nutritional supplements by capillary electrophoresis with direct or indirect UV absorbance detection

PubMed Central

Liu, Huiqing; Ren, Jie

2017-01-01

The branched-chain amino acids (BCAAs) including leucine (Leu), isoleucine (Ile) and valine (Val) play a pivotal role in the human body. Herein, we developed capillary electrophoresis (CE) coupled with conventional UV detector to quantify underivatized BCAAs in two kinds of sport nutritional supplements. For direct UV detection at 195 nm, the BCAAs (Leu, two enantiomers of Ile and Val) were separated in a background electrolyte (BGE) consisting of 40.0 mmol/L sodium tetraborate, and 40.0 mmol/L β-cyclodextrin (β-CD) at pH 10.2. In addition, the indirect UV detection at 264 nm was achieved in a BGE of 2.0 mmol/L Na2HPO4, 10.0 mmol/L p-aminosalicylic acid (PAS) as UV absorbing probe, and 40.0 mmol/L β-CD at pH 12.2. The β-CD significantly benefited the isomeric separation of Leu, L- and D-Ile. The optimal conditions allowed the LODs (limit of detections) of direct and indirect UV absorption detection to be tens μmol/L level, which was comparable to the reported CE inline derivatization method. The RSDs (relative standard deviations) of migration time and peak area were less than 0.91% and 3.66% (n = 6). Finally, CE with indirect UV detection method was applied for the quantitation of BCAAs in two commercial sport nutritional supplements, and good recovery and precision were obtained. Such simple CE method without tedious derivatization process is feasible of quality control and efficacy evaluation of the supplemental proteins. PMID:28640882

Quantification of maltol in Korean ginseng (Panax ginseng) products by high-performance liquid chromatography-diode array detector

PubMed Central

Jeong, Hyun Cheol; Hong, Hee-Do; Kim, Young-Chan; Rhee, Young Kyoung; Choi, Sang Yoon; Kim, Kyung-Tack; Kim, Sung Soo; Lee, Young-Chul; Cho, Chang-Won

2015-01-01

Background: Maltol, as a type of phenolic compounds, is produced by the browning reaction during the high-temperature treatment of ginseng. Thus, maltol can be used as a marker for the quality control of various ginseng products manufactured by high-temperature treatment including red ginseng. For the quantification of maltol in Korean ginseng products, an effective high-performance liquid chromatography-diode array detector (HPLC-DAD) method was developed. Materials and Methods: The HPLC-DAD method for maltol quantification coupled with a liquid-liquid extraction (LLE) method was developed and validated in terms of linearity, precision, and accuracy. An HPLC separation was performed on a C18 column. Results: The LLE methods and HPLC running conditions for maltol quantification were optimized. The calibration curve of the maltol exhibited good linearity (R2 = 1.00). The limit of detection value of maltol was 0.26 μg/mL, and the limit of quantification value was 0.79 μg/mL. The relative standard deviations (RSDs) of the data of the intra- and inter-day experiments were <1.27% and 0.61%, respectively. The results of the recovery test were 101.35–101.75% with an RSD value of 0.21–1.65%. The developed method was applied successfully to quantify the maltol in three ginseng products manufactured by different methods. Conclusion: The results of validation demonstrated that the proposed HPLC-DAD method was useful for the quantification of maltol in various ginseng products. PMID:26246746

Preparation and evaluation of silica-UIO-66 composite as liquid chromatographic stationary phase for fast and efficient separation.

PubMed

Yan, Zhiming; Zheng, Jiangnan; Chen, Jinfeng; Tong, Ping; Lu, Minghua; Lin, Zian; Zhang, Lan

2014-10-31

A silica-UIO-66 composite was fabricated by a simple hydrothermal method and then applied as liquid chromatographic stationary phase for fast and efficient separation. X-ray diffraction patterns showed the presence of UIO-66 crystals in the silica-UIO-66 composites; while scanning electron microscope (SEM) images revealed that silica-UIO-66 composites were a homogeneous mixture of silica bead and UIO-66 crystals. A variety of substituted aromatics, chlorobenzene compounds and polycyclic aromatic hydrocarbons (PAHs) were used to evaluate the retention properties of the silica-UIO-66 composite packed column. Under the optimized conditions, baseline separation of ethylbenzene (EB) and styrene was obtained with high resolution and short retention time. In addition, the silica-UIO-66 composite packed column also showed some advantages in separation of positional isomers, with which baseline separation of EB and xylene, chlorotoluene and dichlorobenzene isomers was achieved. Moreover, the retention mechanisms of these compounds were also discussed in detail. The relative standard deviations (RSDs) for the separation of EB and xylene, chlorotoluene and dichlorobenzene isomers, as well as EB and styrene were 0.42-0.9%, 1.0-1.9%, 0.75-2.0%, and 0.9-2.1% for the retention time, peak area, peak height, and half peak width, respectively. The column efficiencies for EB, p-chlorotoluene, p-dichlorobenzene and styrene were 8780, 9060, 9990 and 5130 plates/m. The successful applications suggested high potentials of silica-MOFs composite as stationary phase for fast and efficient liquid chromatography separation. Copyright © 2014 Elsevier B.V. All rights reserved.

Estimating the sample mean and standard deviation from the sample size, median, range and/or interquartile range.

PubMed

Wan, Xiang; Wang, Wenqian; Liu, Jiming; Tong, Tiejun

2014-12-19

In systematic reviews and meta-analysis, researchers often pool the results of the sample mean and standard deviation from a set of similar clinical trials. A number of the trials, however, reported the study using the median, the minimum and maximum values, and/or the first and third quartiles. Hence, in order to combine results, one may have to estimate the sample mean and standard deviation for such trials. In this paper, we propose to improve the existing literature in several directions. First, we show that the sample standard deviation estimation in Hozo et al.'s method (BMC Med Res Methodol 5:13, 2005) has some serious limitations and is always less satisfactory in practice. Inspired by this, we propose a new estimation method by incorporating the sample size. Second, we systematically study the sample mean and standard deviation estimation problem under several other interesting settings where the interquartile range is also available for the trials. We demonstrate the performance of the proposed methods through simulation studies for the three frequently encountered scenarios, respectively. For the first two scenarios, our method greatly improves existing methods and provides a nearly unbiased estimate of the true sample standard deviation for normal data and a slightly biased estimate for skewed data. For the third scenario, our method still performs very well for both normal data and skewed data. Furthermore, we compare the estimators of the sample mean and standard deviation under all three scenarios and present some suggestions on which scenario is preferred in real-world applications. In this paper, we discuss different approximation methods in the estimation of the sample mean and standard deviation and propose some new estimation methods to improve the existing literature. We conclude our work with a summary table (an Excel spread sheet including all formulas) that serves as a comprehensive guidance for performing meta-analysis in different situations.

A study on the measurement of wrist motion range using the iPhone 4 gyroscope application.

PubMed

Kim, Tae Seob; Park, David Dae Hwan; Lee, Young Bae; Han, Dong Gil; Shim, Jeong Su; Lee, Young Jig; Kim, Peter Chan Woo

2014-08-01

Measuring the range of motion (ROM) of the wrist is an important physical examination conducted in the Department of Hand Surgery for the purpose of evaluation, diagnosis, prognosis, and treatment of patients. The most common method for performing this task is by using a universal goniometer. This study was performed using 52 healthy participants to compare wrist ROM measurement using a universal goniometer and the iPhone 4 Gyroscope application. Participants did not have previous wrist illnesses and their measured values for wrist motion were compared in each direction. Normal values for wrist ROM are 73 degrees of flexion, 71 degrees of extension, 19 degrees of radial deviation, 33 degrees of ulnar deviation, 140 degrees of supination, and 60 degrees of pronation.The average measurement values obtained using the goniometer were 74.2 (5.1) degrees for flexion, 71.1 (4.9) degrees for extension, 19.7 (3.0) degrees for radial deviation, 34.0 (3.7) degrees for ulnar deviation, 140.8 (5.6) degrees for supination, and 61.1 (4.7) degrees for pronation. The average measurement values obtained using the iPhone 4 Gyroscope application were 73.7 (5.5) degrees for flexion, 70.8 (5.1) degrees for extension, 19.5 (3.0) degrees for radial deviation, 33.7 (3.9) degrees for ulnar deviation, 140.4 (5.7) degrees for supination, and 60.8 (4.9) degrees for pronation. The differences between the measurement values by the Gyroscope application and average value were 0.7 degrees for flexion, -0.2 degrees for extension, 0.5 degrees for radial deviation, 0.7 degrees for ulnar deviation, 0.4 degrees for supination, and 0.8 degrees for pronation. The differences in average value were not statistically significant. The authors introduced a new method of measuring the range of wrist motion using the iPhone 4 Gyroscope application that is simpler to use and can be performed by the patient outside a clinical setting.

Analytical probabilistic proton dose calculation and range uncertainties

NASA Astrophysics Data System (ADS)

Bangert, M.; Hennig, P.; Oelfke, U.

2014-03-01

We introduce the concept of analytical probabilistic modeling (APM) to calculate the mean and the standard deviation of intensity-modulated proton dose distributions under the influence of range uncertainties in closed form. For APM, range uncertainties are modeled with a multivariate Normal distribution p(z) over the radiological depths z. A pencil beam algorithm that parameterizes the proton depth dose d(z) with a weighted superposition of ten Gaussians is used. Hence, the integrals ∫ dz p(z) d(z) and ∫ dz p(z) d(z)2 required for the calculation of the expected value and standard deviation of the dose remain analytically tractable and can be efficiently evaluated. The means μk, widths δk, and weights ωk of the Gaussian components parameterizing the depth dose curves are found with least squares fits for all available proton ranges. We observe less than 0.3% average deviation of the Gaussian parameterizations from the original proton depth dose curves. Consequently, APM yields high accuracy estimates for the expected value and standard deviation of intensity-modulated proton dose distributions for two dimensional test cases. APM can accommodate arbitrary correlation models and account for the different nature of random and systematic errors in fractionated radiation therapy. Beneficial applications of APM in robust planning are feasible.

Range and Energy Straggling in Ion Beam Transport

NASA Technical Reports Server (NTRS)

Wilson, John W.; Tai, Hsiang

2000-01-01

A first-order approximation to the range and energy straggling of ion beams is given as a normal distribution for which the standard deviation is estimated from the fluctuations in energy loss events. The standard deviation is calculated by assuming scattering from free electrons with a long range cutoff parameter that depends on the mean excitation energy of the medium. The present formalism is derived by extrapolating Payne's formalism to low energy by systematic energy scaling and to greater depths of penetration by a second-order perturbation. Limited comparisons are made with experimental data.

Simultaneous determination of eleven preservatives in cosmetics by micellar electrokinetic chromatography.

PubMed

Wang, Ping; Ding, Xiaojing; Li, Yun; Yang, Yuanyuan

2012-01-01

A new method for the simultaneous quantitation of 11 preservatives-imidazolidinyl urea, benzyl alcohol, dehydroacetic acid, sorbic acid, phenoxyethanol, benzoic acid, salicylic acid, and four parabens (methyl, ethyl, propyl, and butyl)-in cosmetics by micellar electrokinetic capillary chromatography was established and validated. The separation was performed using an uncoated fused-silica capillary (50 pm id x 60.2 cm, effective length 50 cm) with a running buffer consisting of 15 mmol/L sodium tetraborate, 60 mmol/L boric acid, and 100 mmol/L sodium dodecyl sulfate. A 1:10 dilution of the running buffer was used as the sample buffer to extract the cosmetic samples. The key factors, such as the concentration and pH of the running and sample buffers, which influence quantitative analysis of the above 11 preservatives in cosmetic samples, were investigated in detail. The linear ranges of the calibration curves for imidazolidinyl urea and the other 10 preservatives were 50-1000 and 10-200 mg/L, respectively. The correlation coefficients of the standard curves were all higher than 0.999. The recoveries at the concentrations studied ranged from 93.0 to 102.7%. RSDs were all less than 5%. The new method with simple sample pretreatment met the needs for routine analysis of the 11 preservatives in cosmetics.

Optimized ultrasound-assisted extraction procedure for the analysis of opium alkaloids in papaver plants by cyclodextrin-modified capillary electrophoresis.

PubMed

Fakhari, Ali Reza; Nojavan, Saeed; Ebrahimi, Samad Nejad; Evenhuis, Christopher John

2010-07-01

This study investigated the use of ultrasound-assisted extraction to improve the extraction efficiency of morphine, codeine and thebaine from the papaver plants. Extraction conditions such as type of solvent, temperature, duration, frequency and power level of ultrasonic were optimized and the influences of different parameters on resolution of alkaloids in CE were studied. The optimized condition for CE separation includes a sodium phosphate buffer (100 mM, pH 3.0) containing 5 mM alpha-CD. The optimized extraction conditions for ultrasound-assisted extraction was an extraction time of 1 h, an ultrasonic frequency of 60 kHz with water-methanol (80:20) at 40 degrees C as the extraction solvent. The LOD for alkaloids was found to be 0.1 microg/mL at a signal-to-noise ratio of 3:1. The RSDs for peak areas were in the range of 1.4-4.4%. The amounts of opium alkaloids (mg/100 g dried sample) in four Iranian papaver plants were found to be in the range of 7.8-8.7 (morphine), 5.5-9.5 (codeine) and 1.4-10.4 (thebaine). It should be emphasized that no cleanup of the filtered extract was required; hence, direct determination after extraction drastically simplifies the analytical process.

Simultaneous determination of main reaction components in the reaction mixture during biodiesel production.

PubMed

Sánek, Lubomír; Pecha, Jiří; Kolomazník, Karel

2013-03-01

The proposed analytical method allows for simultaneous determination by GC using a programed temperature vaporization injector and a flame ionization detector of the main reaction components (i.e. glycerol, methyl esters, mono-, di-, and triacylglycerols) in the reaction mixture during biodiesel production. The suggested method is convenient for the rapid and simple evaluation of the kinetic data gained during the transesterification reaction and, also partially serves as an indicator of the quality of biodiesel and mainly, as the indicator of the efficiency of the whole production process (i.e. the conversion of triacylglycerols to biodiesel and its time progress). The optimization of chromatographic conditions (e.g. the oven temperature program, injector setting, amount of derivatization reagent, and the derivatization reaction time) was performed. The method has been validated with crude samples of biodiesel made from waste-cooking oils in terms of linearity, precision, accuracy, sensitivity, and limits of detection and quantification. The results confirmed a satisfactory degree of accuracy and repeatability (the mean RSDs were usually below 2%) necessary for the reliable quantitative determination of all components in the considerable concentration range (e.g. 10-1100 μg/mL in case of methyl esters). Compound recoveries ranging from 96 to 104% were obtained. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymer monolithic capillary microextraction combined on-line with inductively coupled plasma MS for the determination of trace rare earth elements in biological samples.

PubMed

Zhang, Lin; Chen, Beibei; He, Man; Hu, Bin

2013-07-01

A rapid and sensitive method based on polymer monolithic capillary microextraction combined on-line with microconcentric nebulization inductively coupled plasma MS has been developed for the determination of trace/ultratrace rare earth elements in biological samples. For this purpose, the iminodiacetic acid modified poly(glycidyl methacrylate-trimethylolpropane trimethacrylate) monolithic capillary was prepared and characterized by SEM and FTIR spectroscopy. Factors affecting the extraction efficiency, such as sample pH, sample flow rate, sample/eluent volume, and coexisting ions were investigated in detail. Under the optimal conditions, the LODs for rare earth elements were in the range of 0.08 (Er) to 0.97 ng/L (Nd) with a sampling frequency of 8.5 h(-1), and the RSDs were between 1.5% (Sm) and 7.4% (Nd) (c = 20 ng/L, n = 7). The proposed method was successfully applied to the analysis of trace/ultratrace rare earth elements in human urine and serum samples, and the recoveries for the spiked samples were in the range of 82-105%. The developed method was simple, rapid, sensitive, and favorable for the analysis of trace/ultratrace rare earth elements in biological samples with limited sample volume. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microwave-assisted extraction at atmospheric pressure coupled to different clean-up methods for the determination of organophosphorus pesticides in olive and avocado oil.

PubMed

Fuentes, Edwar; Báez, María E; Díaz, Juan

2009-12-18

An effective extraction method was devised for the determination of organophosphorus pesticides (OPPs) in olive and avocado oil samples, using atmospheric pressure microwave-assisted liquid-liquid extraction (APMAE) and solid-phase extraction or low-temperature precipitation as clean-up step. A simple glass system equipped with an air-cooled condenser was designed as an extraction vessel. The pesticides were partitioned between acetonitrile and oil solution in hexane. Analytical determinations were carried out by gas chromatography-flame photometric detection and gas chromatography-tandem mass spectrometry, using a triple quadrupole mass analyzer, for confirmation purposes. Several factors influencing the extraction efficiency were investigated and optimized through fractional factorial design and Doehlert design. Under optimal conditions the recovery of pesticides from oil at 0.025 microg g(-1) ranged from 71% to 103%, except for fenthion in avocado oil, with RSDs < or = 13% (n=5). The LOQ for the entire method ranged from 0.004 to 0.015 microg g(-1). Finally, the proposed method was successfully applied to the extraction and determination of the selected pesticides in 20 commercially packed extra virgin olive oils and four commercially packed avocado oils produced in Chile. Detectable residues of different OPPs were observed in 85% of samples.

Determination of benzoylurea insecticides in food by pressurized liquid extraction and LC-MS.

PubMed

Brutti, Monia; Blasco, Cristina; Picó, Yolanda

2010-01-01

A method based on pressurized liquid extraction and LC-MS/MS has been developed for determining nine benzoylureas (BUs) in fruit, vegetable, cereals, and animal products. Samples (5 g) were homogenized with diatomaceous earth and extracted in a 22 mL cell with 22 mL of ethyl acetate at 80 degrees C and 1500 psi. After solvent concentration and exchange to methanol, BUs were analyzed by LC-MS/MS using an IT mass analyzer, which achieved several transitions of precursor ions that increase selectivity providing identification. LOQs were between 0.002 and 0.01 mg/kg, which are equal or lower than maximum residue limits established by the Codex Alimentarius. Excellent linearity was achieved over a range of concentrations from 0.01 to 1 mg/kg with correlation coefficients 0.995-0.999 (n=7). Validation of the total method was performed by analyzing in quintuplicate seven different commodities (milk, eggs, meat, rice, lettuce, avocado, and lemon) at three concentration levels (0.01, 0.1, and 1 mg/kg). The recoveries ranged from 58 to 97% and the RSDs from 5 to 19% depending on the compound and the commodity. The combination of pressurized liquid extraction with LC-MS/MS provides a sensitive and selective method for the determination of BUs in food.

[Simultaneous determination of six fluorescent whitening agents in plastic and paper packaging materials by high performance liquid chromatography].

PubMed

Zhang, Juzhou; Ji, Shuilin; Cai, Huimei; Li, Jing; Wang, Yongxin; Wang, Jingqiu

2017-11-08

A novel analytical method was developed for the simultaneous determination of six fluorescent whitening agents (FWAs:FWA 135, FWA 184, FWA 185, FWA 199, FWA 378 and FWA 393) in paper and plastic food packaging materials by high performance liquid chromatography with fluorescence detection (HPLC-FLD). The sample was extracted with mixed solution of chloroform and acetonitrile (3:7, v/v), then cleaned up by HLB solid phase extraction column. Qualitative and quantitative analyses were carried out by HPLC. The sample was separated on a Phenomenex C18 column using acetonitrile and 5 mmol/L ammonium acetate aqueous solution as mobile phases. The results indicated that the linear range of FWA393 was 15-1500 μg/L and the linear ranges of the other five FWAs were 5-500 μg/L with correlation coefficients greater than 0.999. The recoveries in spiked samples were between 80.4% and 125.0% with RSDs ( n =6) of 1%-13%. Furthermore, this method was applied to analyze 12 samples in the market to verify the practicality of the method. The method showed the advantages of simplicity, high recovery and good precision, and is suitable for the detection of the six fluorescent whitening agents in food packaging materials.

Sensitive determination of polycyclic aromatic hydrocarbons in water samples by HPLC coupled with SPE based on graphene functionalized with triethoxysilane.

PubMed

Huang, Ke-Jing; Li, Jing; Liu, Yan-Ming; Wang, Lan

2013-02-01

The graphene functionalized with (3-aminopropyl) triethoxysilane was synthesized by a simple hydrothermal reaction and applied as SPE sorbents to extract trace polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. These sorbents possess high adsorption capacity and extraction efficiency due to strong adsorption ability of carbon materials and large specific surface area of nanoparticles, and only 10 mg of sorbents are required to extract PAHs from 100 mL water samples. Several condition parameters, such as eluent and its volume, adsorbent amount, sample volume, sample pH, and sample flow rate, were optimized to achieve good sensitivity and precision. Under the optimized extraction conditions, the method showed good linearity in the range of 1-100 μg/L, repeatability of the extraction (the RSDs were between 1.8 and 2.9%, n = 6), and satisfactory detection limits of 0.029-0.1 μg/L. The recoveries of PAHs spiked in environmental water samples ranged from 84.6 to 109.5%. All these results demonstrated that this new SPE technique was a viable alternative to conventional enrichment techniques for the extraction and analysis of PAHs in complex samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

QuEChERS-based purification method coupled to ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to determine six quaternary ammonium compounds (QACs) in dairy products.

PubMed

Xian, Yanping; Dong, Hao; Wu, Yuluan; Guo, Xindong; Hou, Xiangchang; Wang, Bin

2016-12-01

QuEChERS-based purification coupled with UPLC-MS/MS method, was developed for six quaternary ammonium compounds (QACs) determination in dairy products. Powder samples were firstly dispersed by water. Protein in liquid milk was precipitated and sample solution was extracted by acetonitrile. QuEChERS-based purification was used to purify the solution. QACs were finally separated by HILIC column and detected in MRM mode of MS/MS under ESI(+). The stable isotope benzyl-2,3,4,5,6-d5-dimethyltetradecylammonium bromide (C14-BAC-d5) was used as an internal standard. This method was validated in terms of linearity, sensitivity, precision, accuracy. Linear relations were favorable for QACs over the selected concentration ranges of 0.2-50μg/L, with correlation coefficients greater than 0.999. The limits of detection (LODs) were in the range of 0.4-14.5μg/kg. Recoveries were between 91.2% and 115% with RSDs of 2.8-7.5% for intra-day precision and 3.7-6.7% for inter-day precision. This validated method was successfully applied to determine the QACs concentrations in dairy products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chromium in water by graphite furnace atomic absorption spectrophotometry

USGS Publications Warehouse

McLain, B.J.

1993-01-01

Graphite furnace atomic absorption spectrophotometry is a sensitive, precise, and accurate method for the determination of chromium in natural water samples. The detection limit for this analytical method is 0.4 microg/L with a working linear limit of 25.0 microg/L. The precision at the detection limit ranges from 20 to 57 percent relative standard deviation (RSD) with an improvement to 4.6 percent RSD for concentrations more than 3 microg/L. Accuracy of this method was determined for a variety of reference standards that was representative of the analytical range. The results were within the established standard deviations. Samples were spiked with known concentrations of chromium with recoveries ranging from 84 to 122 percent. In addition, a comparison of data between graphite furnace atomic absorption spectrophotometry and direct-current plasma atomic emission spectrometry resulted in suitable agreement between the two methods, with an average deviation of +/- 2.0 microg/L throughout the analytical range.

Joint US Navy/US Air Force climatic study of the upper atmosphere. Volume 1: January

NASA Astrophysics Data System (ADS)

Changery, Michael J.; Williams, Claude N.; Dickenson, Michael L.; Wallace, Brian L.

1989-07-01

The upper atmosphere was studied based on 1980 to 1985 twice daily gridded analyses produced by the European Centre for Medium Range Weather Forecasts. This volume is for the month of January. Included are global analyses of: (1) Mean temperature standard deviation; (2) Mean geopotential height standard deviation; (3) Mean density standard deviation; (4) Mean density standard deviation (all for 13 levels - 1000, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30 mb); (5) Mean dew point standard deviation for the 13 levels; and (6) Jet stream at levels 500 through 30 mb. Also included are global 5 degree grid point wind roses for the 13 pressure levels.

[Magnetic solid phase extraction combined with gas chromatography-flame photometric detection for the determination of organophosphorus pesticides in juice samples].

PubMed

Huang, Qian; He, Man; Chen, Beibei; Hu, Bin

2014-10-01

A novel method for the determination of organophosphorous pesticides (OPPs) in fresh juice samples was developed. Fe3O4 @ P (St-co-MAA) magnetic microparticles were synthesized and modified with styrene (St) and methacrylic acid (MAA) by coating St and MAA on magnetic particles and characterized by a series of techniques. The results indicated that Fe3 O4 magnetic nanoparticles (MNPs) have been successfully modified with St and MAA. Based on the prepared FeO4 @ P (St-co-MAA) magnetic microparticles, a novel method of magnetic solid phase extraction (MSPE)-gas chromatography (GC)-flame photometric detection (FPD) was developed for the determination of OPPs. The extraction/desorption conditions of MSPE were optimized, and the analytical performance was evaluated under the optimal conditions. The limits of detection (LODs, S/N = 3) for target OPPs were in the range of 0.013-0.305 μg/L with the RSDs (n = 7) ranging from 3.1% to 8.8%. The enrichment factors varied from 406 to 951. The linear ranges were over three orders of magnitudes (R2 > 0.99) and the reproducibilities were 7.4%-14.5% (n = 5). Finally, the proposed MSPE-GC-FPD method was successfully applied to the analysis of the five OPPs in fresh tomato and strawberry juice samples, with the recoveries of target OPPs in the range of 85.4%-118.9% for the spiked samples. The proposed MSPE-GC-FPD method is featured with low cost, fast separation and high enrichment factor.

The SEASAT altimeter wet tropospheric range correction revisited

NASA Technical Reports Server (NTRS)

Tapley, D. B.; Lundberg, J. B.; Born, G. H.

1984-01-01

An expanded set of radiosonde observations was used to calculate the wet tropospheric range correction for the brightness temperature measurements of the SEASAT scanning multichannel microwave radiometer (SMMR). The accuracy of the conventional algorithm for wet tropospheric range correction was evaluated. On the basis of the expanded observational data set, the algorithm was found to have a bias of about 1.0 cm, and a standard deviation 2.8 cm. In order to improve the algorithm, the exact linear, quadratic and logarithmic relationships between brightness temperatures and range corrections were determined. Various combinations of measurement parameters were used to reduce the standard deviation between SEASAT SMMR and radiosonde observations to about 2.1 cm. The performance of various range correction formulas is compared in a table.

A Collaborative Study: Determination of Mycotoxins in Corn, Peanut Butter, and Wheat Flour Using Stable Isotope Dilution Assay (SIDA) and Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).

PubMed

Zhang, Kai; Schaab, Matthew R; Southwood, Gavin; Tor, Elizabeth R; Aston, Linda S; Song, Wenlu; Eitzer, Brian; Majumdar, Sanghamitra; Lapainis, Theodore; Mai, Huy; Tran, Kevin; El-Demerdash, Aref; Vega, Victor; Cai, Yanxuan; Wong, Jon W; Krynitsky, Alexandra J; Begley, Timothy H

2017-08-23

A collaborative study was conducted to evaluate stable isotope dilution assay (SIDA) and LC-MS/MS for the simultaneous determination of aflatoxins B 1 , B 2 , G 1 , and G 2 ; deoxynivalenol; fumonisins B 1 , B 2 , and B 3 ; ochratoxin A; HT-2 toxin; T-2 toxin; and zearalenone in foods. Samples were fortified with 12 13 C uniformly labeled mycotoxins ( 13 C-IS) corresponding to the native mycotoxins and extracted with acetonitrile/water (50:50 v/v), followed by centrifugation, filtration, and LC-MS/MS analysis. In addition to certified reference materials, the six participating laboratories analyzed corn, peanut butter, and wheat flour fortified with the 12 mycotoxins at concentrations ranging from 1.0 to 1000 ng/g. Using their available LC-MS/MS platform, each laboratory developed in-house instrumental conditions for analysis. The majority of recoveries ranged from 80 to 120% with relative standard derivations (RSDs) <20%. Greater than 90% of the average recoveries of the participating laboratories were in the range of 90-110%, with repeatability RSD r (within laboratory) < 10% and reproducibility RSD R (among laboratory) < 15%. All Z scores of the results of certified reference materials were between -2 and 2. Using 13 C-IS eliminated the need for matrix-matched calibration standards for quantitation, simplified sample preparation, and achieved simultaneous identification and quantitation of multiple mycotoxins in a simple LC-MS/MS procedure.

Ionic liquid-impregnated agarose film two-phase micro-electrodriven membrane extraction (IL-AF-μ-EME) for the analysis of antidepressants in water samples.

PubMed

Mohamad Hanapi, Nor Suhaila; Sanagi, Mohd Marsin; Ismail, Abd Khamim; Wan Ibrahim, Wan Aini; Saim, Nor'ashikin; Wan Ibrahim, Wan Nazihah

2017-03-01

The aim of this study was to investigate and apply supported ionic liquid membrane (SILM) in two-phase micro-electrodriven membrane extraction combined with high performance liquid chromatography-ultraviolet detection (HPLC-UV) for pre-concentration and determination of three selected antidepressant drugs in water samples. A thin agarose film impregnated with 1-hexyl-3-methylimidazolium hexafluorophosphate, [C 6 MIM] [PF 6 ], was prepared and used as supported ionic liquid membrane between aqueous sample solution and acceptor phase for extraction of imipramine, amitriptyline and chlorpromazine. Under the optimized extraction conditions, the method provided good linearity in the range of 1.0-1000μgL -1 , good coefficients of determination (r 2 =0.9974-0.9992) and low limits of detection (0.1-0.4μgL -1 ). The method showed high enrichment factors in the range of 110-150 and high relative recoveries in the range of 88.2-111.4% and 90.9-107.0%, for river water and tap water samples, respectively with RSDs of ≤7.6 (n=3). This method was successfully applied to the determination of the drugs in river and tap water samples. It is envisaged that the SILM improved the perm-selectivity by providing a pathway for targeted analytes which resulted in rapid extraction with high degree of selectivity and high enrichment factor. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimization and Comparison of ESI and APCI LC-MS/MS Methods: A Case Study of Irgarol 1051, Diuron, and their Degradation Products in Environmental Samples

NASA Astrophysics Data System (ADS)

Maragou, Niki C.; Thomaidis, Nikolaos S.; Koupparis, Michael A.

2011-10-01

A systematic and detailed optimization strategy for the development of atmospheric pressure ionization (API) LC-MS/MS methods for the determination of Irgarol 1051, Diuron, and their degradation products (M1, DCPMU, DCPU, and DCA) in water, sediment, and mussel is described. Experimental design was applied for the optimization of the ion sources parameters. Comparison of ESI and APCI was performed in positive- and negative-ion mode, and the effect of the mobile phase on ionization was studied for both techniques. Special attention was drawn to the ionization of DCA, which presents particular difficulty in API techniques. Satisfactory ionization of this small molecule is achieved only with ESI positive-ion mode using acetonitrile in the mobile phase; the instrumental detection limit is 0.11 ng/mL. Signal suppression was qualitatively estimated by using purified and non-purified samples. The sample preparation for sediments and mussels is direct and simple, comprising only solvent extraction. Mean recoveries ranged from 71% to 110%, and the corresponding (%) RSDs ranged between 4.1 and 14%. The method limits of detection ranged between 0.6 and 3.5 ng/g for sediment and mussel and from 1.3 to 1.8 ng/L for sea water. The method was applied to sea water, marine sediment, and mussels, which were obtained from marinas in Attiki, Greece. Ion ratio confirmation was used for the identification of the compounds.

Determination of bisphenol A, 4-n-nonylphenol, and 4-tert-octylphenol by temperature-controlled ionic liquid dispersive liquid-phase microextraction combined with high performance liquid chromatography-fluorescence detector.

PubMed

Zhou, Qingxiang; Gao, Yuanyuan; Xie, Guohong

2011-09-15

Present study described a simple, sensitive, and viable method for the determination of bisphenol A, 4-n-nonylphenol and 4-tert-octylphenol in water samples using temperature-controlled ionic liquid dispersive liquid-phase microextraction coupled to high performance liquid chromatography-fluorescence detector. In this experiment, 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)MIM][PF(6)]) was used as the extraction solvent, and bisphenol A, 4-n-nonylphenol and 4-tert-octylphenol were selected as the model analytes. Parameters affecting the extraction efficiency such as the volume of [C(8)MIM][PF(6)], dissolving temperature, extraction time, sample pH, centrifuging time and salting-out effect have been investigated in detail. Under the optimized conditions, good linear relationship was found in the concentration range of 1.0-100 μg L(-1) for BPA, 1.5-150 μg L(-1) for 4-NP, and 3-300 μg L(-1) for 4-OP, respectively. Limits of detection (LOD, S/N=3) were in the range of 0.23-0.48 μg L(-1). Intra day and inter day precisions (RSDs, n=6) were in the range of 4.6-5.5% and 8.5-13.3%, respectively. This method has been also successfully applied to analyze the real water samples at two different spiked concentrations and excellent results were obtained. Copyright © 2011 Elsevier B.V. All rights reserved.

The use of immunoaffinity columns connected in tandem for selective and cost-effective mycotoxin clean-up prior to multi-mycotoxin liquid chromatographic-tandem mass spectrometric analysis in food matrices.

PubMed

Wilcox, Joyce; Donnelly, Carol; Leeman, David; Marley, Elaine

2015-06-26

This paper describes the use of two immunoaffinity columns (IACs) coupled in tandem, providing selective clean-up, based on targeted mycotoxins known to co-occur in specific matrices. An IAC for aflatoxins+ochratoxin A+fumonisins (AOF) was combined with an IAC for deoxynivalenol+zearalenone+T-2/HT-2 toxins (DZT); an IAC for ochratoxin A (O) was combined with a DZT column; and an aflatoxin+ochratoxin (AO) column was combined with a DZT column. By combining pairs of columns it was demonstrated that specific clean-up can be achieved as required for different matrices. Samples of rye flour, maize, breakfast cereal and wholemeal bread were analysed for mycotoxins regulated in the EU, by spiking at levels close to EU limits for adult and infant foods. After IAC clean-up extracts were analysed by LC-MS/MS with quantification using multiple reaction monitoring. Recoveries were found to be in range from 60 to 108%, RSDs below 10% depending on the matrix and mycotoxin combination and LOQs ranged from 0.1n g/g for aflatoxin B1 to 13.0 ng/g for deoxynivalenol. Surplus cereal proficiency test materials (FAPAS(®)) were also analysed with found levels of mycotoxins falling within the satisfactory range of concentrations (Z score ≤ ± 2), demonstrating the accuracy of the proposed multi-mycotoxin IAC methods. Copyright © 2015 Elsevier B.V. All rights reserved.

[Simultaneous determination of 11 constituents in Citrus reticulate 'Chachi' by high performance liquid chromatography].

PubMed

Ye, Xiaolan; Song, Fenyun; Fan, Guorong; Wu, Fuhai

2015-04-01

An HPLC method was developed for the simultaneous determination of 11 constituents, 5-hydroxymethyl furfural (5-HMF), vicenin-2, hesperidin, hesperetin, isosinensetin, sinensetin, tetramethyl-O-isoscutellarein (TEOS), nobiletin, 3, 5, 6, 7, 8, 3', 4'-heptamethoxy- flavone (HEPTA), tangeretin, 5-demethylnobiletin in Citrus reticulate 'Chachi'. The separation was conducted on a Hanbon Benatach C18 column (250 mm x 4.6 mm, 5 µm) with acetonitrile and 0.2% formic acid as mobile phases with gradient elution. The flow rate was 1.0 mL/min. The detection wavelength was 280 nm. The column temperature was 25 °C. The results showed that the correlation coefficients (r) between concentration and chromatographic peak area of the 11 constituents were over 0.998 in the selected linear ranges. The limits of detection (LODs, S/N = 3) and limits of quantification (LOQs, S/N = 10) of the 11 constituents were in the range of 0.0125-1.25 mg/L and 0.0502-4.99 mg/L, respectively. The average recoveries (n = 3) of the 11 constituents were in the range of 96.4%-102.4% and the RSDs were 0.25%-4.01%. The developed method has been successfully applied for the analysis of eight samples from different cultivation regions in Guangdong Province. This method is simple, accurate and effective for the simultaneous determination of the 11 components, and suitable for the quality control of Citrus reticulate 'Chachi'.

Determination of changes in the metabolic profile of avocado fruits (Persea americana) by two CE-MS approaches (targeted and non-targeted).

PubMed

Contreras-Gutiérrez, Paulina K; Hurtado-Fernández, Elena; Gómez-Romero, María; Ignacio Hormaza, José; Carrasco-Pancorbo, Alegría; Fernández-Gutiérrez, Alberto

2013-10-01

A CZE method with two different MS detection conditions (MRM and Full Scan) was developed to determine qualitative and quantitative changes in the metabolic profile of avocado fruits (Persea americana). LODs in MRM approach were found between 20.1 and 203.0 ppb for abscisic acid and perseitol, respectively, whilst in Full Scan, varied within the range 0.22–1.90 ppm for the same metabolites. The RSDs for reproducibility test did not exceed 11.45%. The two MS approaches were used to quantify 10 metabolites (phenolic acids, flavonoids, a carbohydrate, an organic acid, a vitamin and a phytohormone) in 18 samples of avocado at different ripening states, and the achieved results were compared. Perseitol, quinic, chlorogenic, trans-cinnamic, pantothenic and abscisic acids, as well as epicatechin and catechin decreased during the ripening process, whereas ferulic and p-coumaric acids showed the opposite trend. Moreover, some other unknown compounds whose concentration changed largely during ripening were also studied by MS/MS and QTOF MS to get a tentative identification.

[Study on arsenic speciation changes in crude and processed traditional Chinese medicines by HPLC-ICP-MS].

PubMed

Jin, Peng-fei; Wu, Xue-jun; Zou, Ding; Kuang, Yong-mei; Hu, Xin; Jiang, Wen-qing; Sun, Chun-hua

2011-03-01

A HPLC-ICP-MS method for simultaneous determination of As(III), As(V), MMA and DMA in traditional Chinese medicines (TCMs) was established, and the contents of As(III), As(V), MMA and DMA in a TCM with high total arsenic content (Cordyceps) and 5 crude and processed TCMs (Radix Astragali, Radix et Rhizoma Rhei, Radix Scutellariae, Radix Polygoni Multiflori and Radix Rehmanniae) were determined and analyzed. The method validation indicated that the correlative coefficients (r) for all speciations were bigger than 0.9984; the limits of quantitation (LOQ) were from 0.8 to 1.0 microg x L(-1); the reproducibility and stability were satisfactory with all RSDs less than 10%; the spiked recoveries ranged from 82.40% to 119.5%. The results of samples analysis showed that the inorganic arsenic (As(III) and As(V)) was the dominating speciation in the tested TCMs; MMA and DMA were not found in all plant resourced TCMs, but MMA was found in Cordyceps; all the tested TCMs indicated a content increasing of inorganic arsenic after processing.

Solid-phase microextraction coupled with high performance liquid chromatography: a complementary technique to solid-phase microextraction-gas chromatography for the analysis of pesticide residues in strawberries.

PubMed

Wang, Z; Hennion, B; Urruty, L; Montury, M

2000-11-01

Solid-phase microextraction coupled with high performance liquid chromatography has been studied for the analysis of methiocarb, napropamide, fenoxycarb and bupirimate in strawberries. The strawberries were blended and centrifuged. Then, an aliquot of the resulting extracting solution was subjected to solid-phase microextraction (SPME) on a 60 microns polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 45 min at room temperature. The extracted pesticides on the SPME fibre were desorbed into SPME/high performance liquid chromatography (HPLC) interface for HPLC analysis with diode-array detection (DAD). The method is organic solvent-free for the whole extraction process and is simple and easy to manipulate. The detection limits were shown to be at low microgram kg-1 level and the linear response covered the range from 0.05 to 2 mg kg-1 of pesticides in strawberries with a regression coefficient larger than 0.99. A good repeatability with RSDs between 2.92 and 9.25% was obtained, depending on compounds.

[Simultaneous determination of 4 diterpenoids in Rabdosia japonica var.glaucocalyx by HPLC-ESI-MS/MS and cluster analysis].

PubMed

Tian, Ting-Ting; Ma, Ying-Hua; Xie, Wei-Wei; Jin, Yi-Ran; Xu, Hui-Jun; Zhang, Lan-Tong; Du, Ying-Feng

2016-01-01

A quick HPLC-ESI-MS/MS method was established for simultaneous determination of four major diterpenoids in Rabdosia japonica var.glaucocalyx, including glaucocalyxin A, oridonin, hebeirubesensin and enmenol. Analysis was performed on an Agilent ZORBAX SB-C18(4.6 mm×250 mm, 5 μm ) column eluted in a gradient program with methanol and water. The flow rate was 0.8 mL•min⁻¹. Multiple reaction monitoring (MRM) scanning mode was performed in negative ion switching mode to apply for the quantitative determination. The calibration curves for the above four compounds were linear in corresponding injection amount. The average recoveries of the compounds ranged from 92.40% to 105.9%, with RSDs of 1.7%-6.5%. The method is simple, rapid, accurate with good repeatability, which can provide a reference for overcalling evaluation the quality of R. japonica var.glaucocalyx. The result of cluster analysis- showed that the quality of R. japonica glaucocalyx var. greatly varied between areas and parts. Copyright© by the Chinese Pharmaceutical Association.

Miniaturized solid-phase extraction of macrolide antibiotics in honey and bovine milk using mesoporous MCM-41 silica as sorbent.

PubMed

Du, Li-Jing; Yi, Ling; Ye, Li-Hong; Chen, Yu-Bo; Cao, Jun; Peng, Li-Qing; Shi, Yu-Ting; Wang, Qiu-Yan; Hu, Yu-Han

2018-02-16

A simple and effective method of miniaturized solid-phase extraction (mini-SPE) was developed for the simultaneous purification and enrichment of macrolide antibiotics (MACs) (i.e. azithromycin, clarithromycin, erythromycin, lincomycin and roxithromycin) from honey and skim milk. Mesoporous MCM-41 silica was synthesized and used as sorbent in mini-SPE. Several key parameters affecting the performance of mini-SPE procedure were thoroughly investigated, including sorbent materials, amount of sorbent and elution solvents. Under the optimized condition, satisfactory linearity (r 2  > 0.99), acceptable precision (RSDs, 0.3-7.1%), high sensitivity (limit of detection in the range of 0.01-0.76 μg/kg), and good recoveries (83.21-105.34%) were obtained. With distinct advantages of simplicity, reliability and minimal sample requirement, the proposed mini-SPE procedure coupled with ultrahigh performance liquid chromatography and quadrupole time-of-flight tandem mass spectrometry could become an alternative tool to analyze the residues of MACs in complex food matrixes. Copyright © 2018 Elsevier B.V. All rights reserved.

Analysis of 16 phthalic acid esters in food simulants from plastic food contact materials by LC-ESI-MS/MS.

PubMed

Li, Xiaojing; Xiong, Wenming; Lin, Hua; Zhuo, Liyang; Lv, Shuiyuan; Tang, Xi; Chen, Minshi; Zou, Zhexiang; Lin, Zhenyu; Qiu, Bin; Chen, Guonan

2013-02-01

An RP LC-ESI-MS/MS method for the determination of the migration of 16 primary phthalic acid esters from plastic samples has been developed using distilled water, 3% acetic acid, 10% alcohol, and olive oil as food simulants. Detection limits were 1.6-18.5 μg/kg in distilled water, 1.4-17.3 μg/kg in 3% acetic acid, 1.4-19.2 μg/kg in 10% alcohol, and 31.9-390.8 μg/kg in olive oil. The RSDs were in the range of 0.07-11.28%. The real plastic products inspection showed that only few analyzed samples were phthalates contaminated. Bis-2-ethylhexyl ester and dibutyl phthalate were the common items migrated from the plastic products into food and feeds, but the migration concentrations were far below the limits set by European Union (1.5 mg/kg for bis-2-ethylhexyl ester and 0.3 mg/kg for dibutyl phthalate). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermophilic Geobacillus galactosidasius sp. nov. loaded γ-Fe2O3 magnetic nanoparticle for the preconcentrations of Pb and Cd.

PubMed

Özdemir, Sadin; Kilinç, Ersin; Okumuş, Veysi; Poli, Annarita; Nicolaus, Barbara; Romano, Ida

2016-02-01

Thermophilic bacteria, Geobacillus galactosidasius sp nov. was loaded on γ-Fe2O3 magnetic nanoparticle for the preconcentrations of Pb and Cd by solid phase extraction before ICP-OES. pH and flow rate of the solution, amounts of biosorbent and magnetic nanoparticle, volume of sample solution, effects of the possible interferic ions were investigated in details. Linear calibration curves were constructed in the concentration ranges of 1.0-60ngmL(-1) for Pb and Cd. The RSDs of the method were lower than 2.8% for Pb and 3.8% for Cd. Certified and standard reference samples of fortified water, wastewater, poplar leaves, and simulated fresh water were used to accurate the method. LOD values were found as 0.07 and 0.06ngmL(-1) respectively for Pb and Cd. The biosorption capacities were found as 34.3mgg(-1) for Pb and 37.1mgg(-1) for Cd. Pb and Cd concentrations in foods were determined. Surface microstructure was investigated by SEM-EDX. Copyright © 2015 Elsevier Ltd. All rights reserved.

Towards the identification of alkaline phosphatase binding ligands in Li-Dan-Hua-Shi pills: A Box-Behnken design optimized affinity selection approach tandem with UHPLC-Q-TOF/MS analysis.

PubMed

Tao, Yi; Huang, Surun; Gu, Xianghui; Li, Weidong; Cai, Baochang

2018-05-30

Alkaline phosphatase conjugated magnetic microspheres were synthesized via amide reaction, and employed as an effective adsorbent in affinity selection of binding ligands followed by UHPLC-Q-TOF/MS analysis. The analytical validity of the developed approach was evaluated under optimized conditions and the following figures of merit were obtained: linearity, 0.01-0.5 g L -1 with good determination coefficients (R 2  = 0.9992); limits of detection (LODs), 0.003 g L -1 ; and limits of quantitation (LOQ), 0.01 g L -1 . The precision (RSD%) of the proposed affinity selection approach was studied based on intra-day (0.8%) and inter-day (1.3%) precisions. Finally, the adsorbent was successfully applied to identification of binding ligands in Li-Dan-Hua-Shi pills and good recoveries were obtained in the range from 96.9 to 99.4% (RSDs 1.6-3.0%). Copyright © 2018 Elsevier B.V. All rights reserved.

Estimating extreme stream temperatures by the standard deviate method

NASA Astrophysics Data System (ADS)

Bogan, Travis; Othmer, Jonathan; Mohseni, Omid; Stefan, Heinz

2006-02-01

It is now widely accepted that global climate warming is taking place on the earth. Among many other effects, a rise in air temperatures is expected to increase stream temperatures indefinitely. However, due to evaporative cooling, stream temperatures do not increase linearly with increasing air temperatures indefinitely. Within the anticipated bounds of climate warming, extreme stream temperatures may therefore not rise substantially. With this concept in mind, past extreme temperatures measured at 720 USGS stream gauging stations were analyzed by the standard deviate method. In this method the highest stream temperatures are expressed as the mean temperature of a measured partial maximum stream temperature series plus its standard deviation multiplied by a factor KE (standard deviate). Various KE-values were explored; values of KE larger than 8 were found physically unreasonable. It is concluded that the value of KE should be in the range from 7 to 8. A unit error in estimating KE translates into a typical stream temperature error of about 0.5 °C. Using a logistic model for the stream temperature/air temperature relationship, a one degree error in air temperature gives a typical error of 0.16 °C in stream temperature. With a projected error in the enveloping standard deviate dKE=1.0 (range 0.5-1.5) and an error in projected high air temperature d Ta=2 °C (range 0-4 °C), the total projected stream temperature error is estimated as d Ts=0.8 °C.

Refractive index, molar refraction and comparative refractive index study of propylene carbonate binary liquid mixtures.

PubMed

Wankhede, Dnyaneshwar Shamrao

2012-06-01

Refractive indices (n) have been experimentally determined for the binary liquid-liquid mixtures of Propylene carbonate (PC) (1) with benzene, ethylbenzene, o-xylene and p-xylene (2) at 298.15, 303.15 and 308.15 K over the entire mole fraction range. The experimental values of n are utilised to calculate deviation in refractive index (Δn), molar refraction (R) and deviation in molar refraction (ΔR). A comparative study of Arago-Biot (A-B), Newton (NW), Eyring and John (E-J) equations for determining refractive index of a liquid has been carried out to test their validity for all the binary mixtures over the entire composition range at 298.15 K. Comparison of various mixing relations is represented in terms of average deviation (AVD). The Δn and ΔR values have been fitted to Redlich-Kister equation at 298.15 K and standard deviations have been calculated. The results are discussed in terms of intermolecular interactions present amongst the components.

Selective mixed-bed solid phase extraction of atrazine herbicide from environmental water samples using molecularly imprinted polymer.

PubMed

Zarejousheghani, Mashaalah; Fiedler, Petra; Möder, Monika; Borsdorf, Helko

2014-11-01

A novel approach for the selective extraction of organic target compounds from water samples has been developed using a mixed-bed solid phase extraction (mixed-bed SPE) technique. The molecularly imprinted polymer (MIP) particles are embedded in a network of silica gel to form a stable uniform porous bed. The capabilities of this method are demonstrated using atrazine as a model compound. In comparison to conventional molecularly imprinted-solid phase extraction (MISPE), the proposed mixed-bed MISPE method in combination with gas chromatography-mass spectrometry (GC-MS) analysis enables more reproducible and efficient extraction performance. After optimization of operational parameters (polymerization conditions, bed matrix ingredients, polymer to silica gel ratio, pH of the sample solution, breakthrough volume plus washing and elution conditions), improved LODs (1.34 µg L(-1) in comparison to 2.25 µg L(-1) obtained using MISPE) and limits of quantification (4.5 µg L(-1) for mixed-bed MISPE and 7.5 µg L(-1) for MISPE) were observed for the analysis of atrazine. Furthermore, the relative standard deviations (RSDs) for atrazine at concentrations between 5 and 200 µg L(-1) ranged between 1.8% and 6.3% compared to MISPE (3.5-12.1%). Additionally, the column-to-column reproducibility for the mixed-bed MISPE was significantly improved to 16.1%, compared with 53% that was observed for MISPE. Due to the reduced bed-mass sorbent and at optimized conditions, the total amount of organic solvents required for conditioning, washing and elution steps reduced from more than 25 mL for conventional MISPE to less than 2 mL for mixed-bed MISPE. Besides reduced organic solvent consumption, total sample preparation time of the mixed-bed MISPE method relative to the conventional MISPE was reduced from more than 20 min to less than 10 min. The amount of organic solvent required for complete elution diminished from 3 mL (conventional MISPE) to less than 0.4 mL with the mixed-bed technique shows its inherent potential for online operation with an analytical instrument. In order to evaluate the selectivity and matrix effects of the developed mixed-bed MISPE method, it was applied as an extraction technique for atrazine from environmental wastewater and river water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Identification and quantification of three genetically modified insect resistant cotton lines using conventional and TaqMan real-time polymerase chain reaction methods.

PubMed

Yang, Litao; Pan, Aihu; Zhang, Kewei; Guo, Jinchao; Yin, Changsong; Chen, Jianxiu; Huang, Cheng; Zhang, Dabing

2005-08-10

As the genetically modified organisms (GMOs) labeling policies are issued in many countries, qualitative and quantitative polymerase chain reaction (PCR) techniques are increasingly used for the detection of genetically modified (GM) crops in foods. Qualitative PCR and TaqMan real-time quantitative PCR methods to detect and identify three varieties of insect resistant cotton, i.e., Mon531 cotton (Monsanto Co.) and GK19 and SGK321 cottons (Chinese Academy of Agricultural Sciences), which were approved for commercialization in China, were developed in this paper. Primer pairs specific to inserted DNAs, such as Cowpea trypsin inhibitor (CpTI) gene of SGK321 cotton and the specific junction DNA sequences containing partial Cry1A(c) gene and NOS terminator of Mon531, GK19, and SGK321 cotton varieties were designed to conduct the identified PCR assays. In conventional specific identified PCR assays, the limit of detection (LOD) was 0.05% for Mon531, GK19, or SGK321 in 100 ng of cotton genomic DNA for one reaction. Also, the multiplex PCR method for screening the three GM cottons was also established, which could save time and cost in practical detection. Furthermore, a real-time quantitative PCR assay based on TaqMan chemistry for detection of insect resistant gene, Cry1A(c), was developed. This assay also featured the use of a standard plasmid as a reference molecule, which contained both a specific region of the transgene Cry1A(c) and an endogenous stearoyl-acyl carrier protein desaturase (Sad1) gene of the cotton. In quantitative PCR assay, the quantification range was from 0.01 to 100% in 100 ng of the genome DNA template, and in the detection of 1.0, 3.0, and 5.0% levels of three insect resistant cotton lines, respectively, all of the relative standard deviations (RSDs) were less than 8.2% except for the GM cotton samples with 1.0% Mon531 or GK19, which meant that our real-time PCR assays involving the use of reference molecule were reliable and practical for GM insect resistant cottons quantification. All of these results indicated that our established conventional and TaqMan real-time PCR assays were applicable to detect the three insect resistant cottons qualitatively and quantitatively.

Determination of nitric oxide metabolites, nitrate and nitrite, in Anopheles culicifacies mosquito midgut and haemolymph by anion exchange high-performance liquid chromatography: plausible mechanism of refractoriness

PubMed Central

Sharma, Arun; Raghavendra, Kamaraju; Adak, Tridibesh; Dash, Aditya P

2008-01-01

Background The diverse physiological and pathological role of nitric oxide in innate immune defenses against many intra and extracellular pathogens, have led to the development of various methods for determining nitric oxide (NO) synthesis. NO metabolites, nitrite (NO2-) and nitrate (NO3-) are produced by the action of an inducible Anopheles culicifacies NO synthase (AcNOS) in mosquito mid-guts and may be central to anti-parasitic arsenal of these mosquitoes. Method While exploring a plausible mechanism of refractoriness based on nitric oxide synthase physiology among the sibling species of An. culicifacies, a sensitive, specific and cost effective high performance liquid chromatography (HPLC) method was developed, which is not influenced by the presence of biogenic amines, for the determination of NO2- and NO3- from mosquito mid-guts and haemolymph. Results This method is based on extraction, efficiency, assay reproducibility and contaminant minimization. It entails de-proteinization by centrifugal ultra filtration through ultracel 3 K filter and analysis by high performance anion exchange liquid chromatography (Sphereclone, 5 μ SAX column) with UV detection at 214 nm. The lower detection limit of the assay procedure is 50 pmoles in all midgut and haemolymph samples. Retention times for NO2- and NO3- in standards and in mid-gut samples were 3.42 and 4.53 min. respectively. Assay linearity for standards ranged between 50 nM and 1 mM. Recoveries of NO2- and NO3- from spiked samples (1–100 μM) and from the extracted standards (1–100 μM) were calculated to be 100%. Intra-assay and inter assay variations and relative standard deviations (RSDs) for NO2- and NO3- in spiked and un-spiked midgut samples were 5.7% or less. Increased levels NO2- and NO3- in midguts and haemolymph of An. culicifacies sibling species B in comparison to species A reflect towards a mechanism of refractoriness based on AcNOS physiology. Conclusion HPLC is a sensitive and accurate technique for identification and quantifying pmole levels of NO metabolites in mosquito midguts and haemolymph samples that can be useful for clinical investigations of NO biochemistry, physiology and pharmacology in various biological samples. PMID:18442373

Optimization and application of ICPMS with dynamic reaction cell for precise determination of 44Ca/40Ca isotope ratios.

PubMed

Boulyga, Sergei F; Klötzli, Urs; Stingeder, Gerhard; Prohaska, Thomas

2007-10-15

An inductively coupled plasma mass spectrometer with dynamic reaction cell (ICP-DRC-MS) was optimized for determining (44)Ca/(40)Ca isotope ratios in aqueous solutions with respect to (i) repeatability, (ii) robustness, and (iii) stability. Ammonia as reaction gas allowed both the removal of (40)Ar+ interference on (40)Ca+ and collisional damping of ion density fluctuations of an ion beam extracted from an ICP. The effect of laboratory conditions as well as ICP-DRC-MS parameters such a nebulizer gas flow rate, rf power, lens potential, dwell time, or DRC parameters on precision and mass bias was studied. Precision (calculated using the "unbiased" or "n - 1" method) of a single isotope ratio measurement of a 60 ng g(-1) calcium solution (analysis time of 6 min) is routinely achievable in the range of 0.03-0.05%, which corresponded to the standard error of the mean value (n = 6) of 0.012-0.020%. These experimentally observed RSDs were close to theoretical precision values given by counting statistics. Accuracy of measured isotope ratios was assessed by comparative measurements of the same samples by ICP-DRC-MS and thermal ionization mass spectrometry (TIMS) by using isotope dilution with a (43)Ca-(48)Ca double spike. The analysis time in both cases was 1 h per analysis (10 blocks, each 6 min). The delta(44)Ca values measured by TIMS and ICP-DRC-MS with double-spike calibration in two samples (Ca ICP standard solution and digested NIST 1486 bone meal) coincided within the obtained precision. Although the applied isotope dilution with (43)Ca-(48)Ca double-spike compensates for time-dependent deviations of mass bias and allows achieving accurate results, this approach makes it necessary to measure an additional isotope pair, reducing the overall analysis time per isotope or increasing the total analysis time. Further development of external calibration by using a bracketing method would allow a wider use of ICP-DRC-MS for routine calcium isotopic measurements, but it still requires particular software or hardware improvements aimed at reliable control of environmental effects, which might influence signal stability in ICP-DRC-MS and serve as potential uncertainty sources in isotope ratio measurements.

Joint US Navy/US Air Force climatic study of the upper atmosphere. Volume 7: July

NASA Astrophysics Data System (ADS)

Changery, Michael J.; Williams, Claude N.; Dickenson, Michael L.; Wallace, Brian L.

1989-07-01

The upper atmosphere was studied based on 1980 to 1985 twice daily gridded analysis produced by the European Centre for Medium Range Weather Forecasts. This volume is for the month of July. Included are global analyses of: (1) Mean temperature/standard deviation; (2) Mean geopotential height/standard deviation; (3) Mean density/standard deviation; (4) Height and vector standard deviation (all at 13 pressure levels - 1000, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30 mb); (5) Mean dew point standard deviation at levels 1000 through 30 mb; and (6) Jet stream at levels 500 through 30 mb. Also included are global 5 degree grid point wind roses for the 13 pressure levels.

Joint US Navy/US Air Force climatic study of the upper atmosphere. Volume 10: October

NASA Astrophysics Data System (ADS)

Changery, Michael J.; Williams, Claude N.; Dickenson, Michael L.; Wallace, Brian L.

1989-07-01

The upper atmosphere was studied based on 1980 to 1985 twice daily gridded analysis produced by the European Centre for Medium Range Weather Forecasts. This volume is for the month of October. Included are global analyses of: (1) Mean temperature/standard deviation; (2) Mean geopotential height/standard deviation; (3) Mean density/standard deviation; (4) Height and vector standard deviation (all at 13 pressure levels - 1000, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30 mb); (5) Mean dew point/standard deviation at levels 1000 through 30 mb; and (6) Jet stream at levels 500 through 30 mb. Also included are global 5 degree grid point wind roses for the 13 pressure levels.

Joint US Navy/US Air Force climatic study of the upper atmosphere. Volume 3: March

NASA Astrophysics Data System (ADS)

Changery, Michael J.; Williams, Claude N.; Dickenson, Michael L.; Wallace, Brian L.

1989-11-01

The upper atmosphere was studied based on 1980 to 1985 twice daily gridded analysis produced by the European Centre for Medium Range Weather Forecasts. This volume is for the month of March. Included are global analyses of: (1) Mean Temperature Standard Deviation; (2) Mean Geopotential Height Standard Deviation; (3) Mean Density Standard Deviation; (4) Height and Vector Standard Deviation (all for 13 pressure levels - 1000, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30 mb); (5) Mean Dew Point Standard Deviation for levels 1000 through 30 mb; and (6) Jet stream for levels 500 through 30 mb. Also included are global 5 degree grid point wind roses for the 13 pressure levels.

Joint US Navy/US Air Force climatic study of the upper atmosphere. Volume 2: February

NASA Astrophysics Data System (ADS)

Changery, Michael J.; Williams, Claude N.; Dickenson, Michael L.; Wallace, Brian L.

1989-09-01

The upper atmosphere was studied based on 1980 to 1985 twice daily gridded analyses produced by the European Centre for Medium Range Weather Forecasts. This volume is for the month of February. Included are global analyses of: (1) Mean temperature standard deviation; (2) Mean geopotential height standard deviation; (3) Mean density standard deviation; (4) Height and vector standard deviation (all for 13 pressure levels - 1000, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30 mb); (5) Mean dew point standard deviation for the 13 levels; and (6) Jet stream for levels 500 through 30 mb. Also included are global 5 degree grid point wind roses for the 13 pressure levels.

Joint US Navy/US Air Force climatic study of the upper atmosphere. Volume 4: April

NASA Astrophysics Data System (ADS)

Changery, Michael J.; Williams, Claude N.; Dickenson, Michael L.; Wallace, Brian L.

1989-07-01

The upper atmosphere was studied based on 1980 to 1985 twice daily gridded analyses produced by the European Centre for Medium Range Weather Forecasts. This volume is for the month of April. Included are global analyses of: (1) Mean temperature standard deviation; (2) Mean geopotential height standard deviation; (3) Mean density standard deviation; (4) Height and vector standard deviation (all for 13 pressure levels - 1000, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, 30 mb); (5) Mean dew point standard deviation for the 13 levels; and (6) Jet stream for levels 500 through 30 mb. Also included are global 5 degree grid point wind roses for the 13 pressure levels.