Determination of diacylhydrazines-type insect growth regulator JS-118 residues in cabbage and soil by high performance liquid chromatography with DAD detection.

PubMed

Hu, J-Y; Deng, Z-B; Qin, D-M

2009-12-01

JS-118 is a diacylhydrazines-type insect growth regulator used extensively in China now. An analytical method for residues determination of JS-118 in cabbage and soil samples by high performance liquid chromatography with DAD detection was established and optimized. Primary secondary amine solid phase extraction cartridge was used for sample preparation. Mean recoveries for the analyte ranged from 96.6% to 107.0% with CV value less than 4.7%. The limit of quantification is 0.01 mg/kg. Direct confirmation of JS-118 residues in samples was realized by high performance liquid chromatography-mass spectrometry. The proposed method is simple, rapid and reliable to perform and could be utilized for monitoring of pesticides residues.

Ultra-Trace Analysis of Nine Macrolides, including Tulathromycin A (Draxxin), in Edible Animal Tissues with Mini-Column Liquid Chromatography Tandem Mass Spectrometry

USDA-ARS?s Scientific Manuscript database

Analysis of 9 macrolides is presented, including tulathromycin A (Draxxin), in beef, poultry and pork muscle with a simple multi-residue extraction and analysis method using high performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The extraction method inv...

Liquid Chromatographic Detection of Permethrin from Filter Paper Wipes of White-tailed Deer

USDA-ARS?s Scientific Manuscript database

A simple, small-scale method for the determination of the presence or absence of permethrin on the hair coat of white-tailed deer, Odocoileus virginianus (Zimmermann), by high performance liquid chromatography was developed. White-tailed deer in South Texas and the northeastern U.S. are routinely tr...

Determination of MDMA, MDEA and MDA in urine by high performance liquid chromatography with fluorescence detection.

PubMed

da Costa, José Luiz; da Matta Chasin, Alice Aparecida

2004-11-05

This paper describes the development and validation of analytical methodology for the determination of the use of MDMA, MDEA and MDA in urine. After a simple liquid extraction, the analyses were carried out on a high performance liquid chromatography (HPLC) in an octadecyl column, with fluorescence detection. The mobile phase using a sodium dodecyl sulfate ion-pairing reagent allows good separation and efficiency. The method showed good linearity and precision. Recovery was between 85 and 102% and detection limits were 10, 15 and 20 ng/ml for MDA, MDMA and MDEA, respectively. No interfering substances were detected with fluorescence detection.

Simple and rapid high-performance liquid chromatographic method for the determination of aspartame and its metabolites in foods.

PubMed

Gibbs, B F; Alli, I; Mulligan, C N

1996-02-23

A method for the determination of aspartame (N-L-alpha-aspartyl-L-phenylalanine methyl ester) and its metabolites, applicable on a routine quality assurance basis, is described. Liquid samples (diet Coke, 7-Up, Pepsi, etc.) were injected directly onto a mini-cartridge reversed-phase column on a high-performance liquid chromatographic system, whereas solid samples (Equal, hot chocolate powder, pudding, etc.) were extracted with water. Optimising chromatographic conditions resulted in resolved components of interest within 12 min. The by-products were confirmed by mass spectrometry. Although the method was developed on a two-pump HPLC system fitted with a diode-array detector, it is straightforward and can be transformed to the simplest HPLC configuration. Using a single-piston pump (with damper), a fixed-wavelength detector and a recorder/integrator, the degradation of products can be monitored as they decompose. The results obtained were in harmony with previously reported tedious methods. The method is simple, rapid, quantitative and does not involve complex, hazardous or toxic chemistry.

Simultaneous determination of niacin and pyridoxine at trace levels by using diode array high-performance liquid chromatography and liquid chromatography with quadrupole time-of-flight tandem mass spectrometry.

PubMed

Sel, Sabriye; Öztürk Er, Elif; Bakırdere, Sezgin

2017-12-01

A highly sensitive and simple diode-array high-performance liquid chromatography and liquid chromatography with quadrupole time-of-flight tandem mass spectrometry method was developed for the simultaneous determination of niacin and pyridoxine in pharmaceutical drugs, tap water, and wastewater samples. To determine the in vivo behavior of niacin and pyridoxine, analytes were subjected to simulated gastric conditions. The calibration plots of the diode-array high-performance liquid chromatography and liquid chromatography with quadrupole time-of-flight tandem mass spectrometry method showed good linearity over a wide concentration range with close to 1.0 correlation coefficients for both analytes. The limit of detection/limit of quantitation values for liquid chromatography quadrupole time-of-flight tandem mass spectrometry analysis were 1.98/6.59 and 1.3/4.4 μg/L for niacin and pyridoxine, respectively, while limit of detection/limit of quantitation values for niacin and pyridoxine in high-performance liquid chromatography analysis were 3.7/12.3 and 5.7/18.9 μg/L, respectively. Recovery studies were also performed to show the applicability of the developed methods, and percentage recovery values were found to be 90-105% in tap water and 94-97% in wastewater for both analytes. The method was also successfully applied for the qualitative and quantitative determination of niacin and pyridoxine in drug samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simple and rapid analysis of endocrine disruptors in liquid medicines and intravenous injection solutions by automated in-tube solid-phase microextraction/high performance liquid chromatography.

PubMed

Mitani, Kurie; Narimatsu, Shizuo; Izushi, Fumio; Kataoka, Hiroyuki

2003-07-14

A simple and rapid method was developed for analyzing contamination of endocrine disruptors in liquid medicines and intravenous injection solutions. Endocrine disrupting compounds such as bisphenol A (BPA), alkylphenols and phthalates were quantitated by on-line in-tube solid-phase microextraction coupled with high performance liquid chromatography (in-tube SPME/HPLC) with UV detection. The liquid medicines and intravenous injection solutions could be used directly without any pretreatment, and the BPA, alkylphenols and phthalates in these solutions were automatically analyzed. The limits of quantification for these compounds were 1-10 ng/ml. Recoveries of these compounds spiked to the intravenous injection solutions was over 80%, except for some phthalates. Di-n-butyl phthalate (DBP) was detected at a concentration of 7-60 ng/ml in most intravenous injection solutions in plastic containers, but it was not detected in solutions in glass bottles. Diethyl phthalate, di-n-propyl phthalate, DBP and di-2-ethylhexyl phthalate (DEHP) were also detected in syrup, lotion and eye drops in plastic containers. On the other hand, BPA and alkylphenols were not detected at all in these solutions. DEHP contamination from an administration set increased when total vitamin formulation was added to the infusion solution. DEHP was easily leached from polyvinyl chloride tubing by polysorbate 80. The in-tube SPME/HPLC method is simple, rapid and automatic, and it provides a useful tool for the screening and determination of endocrine disruptor contamination in liquid medicines and intravenous injection solutions.

Simultaneous Determination of Food-Related Biogenic Amines and Precursor Amino Acids Using in Situ Derivatization Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction by Ultra-High-Performance Liquid Chromatography Tandem Mass Spectrometry.

PubMed

He, Yongrui; Zhao, Xian-En; Wang, Renjun; Wei, Na; Sun, Jing; Dang, Jun; Chen, Guang; Liu, Zhiqiang; Zhu, Shuyun; You, Jinmao

2016-11-02

A simple, rapid, sensitive, selective, and environmentally friendly method, based on in situ derivatization ultrasound-assisted dispersive liquid-liquid microextraction (in situ DUADLLME) coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) using multiple reaction monitoring (MRM) mode has been developed for the simultaneous determination of food-related biogenic amines and amino acids. A new mass-spectrometry-sensitive derivatization reagent 4'-carbonyl chloride rosamine (CCR) was designed, synthesized, and first reported. Parameters and conditions of in situ DUADLLME and UHPLC-MS/MS were optimized in detail. Under the optimized conditions, the in situ DUADLLME was completed speedily (within 1 min) with high derivatization efficiencies (≥98.5%). With the cleanup and concentration of microextraction step, good analytical performance was obtained for the analytes. The results showed that this method was accurate and practical for quantification of biogenic amines and amino acids in common food samples (red wine, beer, wine, cheese, sausage, and fish).

Measuring Drag Force in Newtonian Liquids

ERIC Educational Resources Information Center

Mawhinney, Matthew T.; O'Donnell, Mary Kate; Fingerut, Jonathan; Habdas, Piotr

2012-01-01

The experiments described in this paper have two goals. The first goal is to show how students can perform simple but fundamental measurements of objects moving through simple liquids (such as water, oil, or honey). In doing so, students can verify Stokes' law, which governs the motion of spheres through simple liquids, and see how it fails at…

Low Density Solvent-Based Dispersive Liquid-Liquid Microextraction for the Determination of Synthetic Antioxidants in Beverages by High-Performance Liquid Chromatography

PubMed Central

Çabuk, Hasan; Köktürk, Mustafa

2013-01-01

A simple and efficient method was established for the determination of synthetic antioxidants in beverages by using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography with ultraviolet detection. Butylated hydroxy toluene, butylated hydroxy anisole, and tert-butylhydroquinone were the antioxidants evaluated. Experimental parameters including extraction solvent, dispersive solvent, pH of sample solution, salt concentration, and extraction time were optimized. Under optimal conditions, the extraction recoveries ranged from 53 to 96%. Good linearity was observed by the square of correlation coefficients ranging from 0.9975 to 0.9997. The relative standard deviations ranged from 1.0 to 5.2% for all of the analytes. Limits of detection ranged from 0.85 to 2.73 ng mL−1. The method was successfully applied for determination of synthetic antioxidants in undiluted beverage samples with satisfactory recoveries. PMID:23853535

Fast, simple and efficient salting-out assisted liquid-liquid extraction of naringenin from fruit juice samples prior to their enantioselective determination by liquid chromatography.

PubMed

Magiera, Sylwia; Kwietniowska, Ewelina

2016-11-15

In this study, an easy, simple and efficient method for the determination of naringenin enantiomers in fruit juices after salting-out-assisted liquid-liquid extraction (SALLE) and high-performance liquid chromatography (HPLC) with diode-array detection (DAD) was developed. The sample treatment is based on the use of water-miscible acetonitrile as the extractant and acetonitrile phase separation under high-salt conditions. After extraction, juice samples were incubated with hydrochloric acid in order to achieve hydrolysis of naringin to naringenin. The hydrolysis parameters were optimized by using a half-fraction factorial central composite design (CCD). After sample preparation, chromatographic separation was obtained on a Chiralcel® OJ-RH column using the mobile phase consisting of 10mM aqueous ammonium acetate:methanol:acetonitrile (50:30:20; v/v/v) with detection at 288nm. The average recovery of the analyzed compounds ranged from 85.6 to 97.1%. The proposed method was satisfactorily used for the determination of naringenin enantiomers in various fruit juices samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Molecularly imprinted polymer cartridges coupled on-line with high performance liquid chromatography for simple and rapid analysis of dextromethorphan in human plasma samples.

PubMed

Moein, Mohammad Mahdi; Javanbakht, Mehran; Akbari-Adergani, Behrouz

2011-04-01

In this paper, a novel method is described for automated determination of dextromethorphan in biological fluids using molecularly imprinted solid-phase extraction (MISPE) as a sample clean-up technique combined with high performance liquid chromatography (HPLC). The water-compatible molecularly imprinted polymers (MIPs) were prepared using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker, chloroform as porogen and dextromethorphan as template molecule. These imprinted polymers were used as solid-phase extraction sorbent for the extraction of dextromethorphan from human plasma samples. Various parameters affecting the extraction efficiency of the MIP cartridges were evaluated. The high selectivity of the sorbent coupled to the high performance liquid chromatographic system permitted a simple and rapid analysis of this drug in plasma samples with limits of detection (LOD) and quantification (LOQ) of 0.12 ng/mL and 0.35 ng/mL, respectively. The MIP selectivity was evaluated by analyzing of the dextromethorphan in presence of several substances with similar molecular structures and properties. Results from the HPLC analyses showed that the recoveries of dextromethorphan using MIP cartridges from human plasma samples in the range of 1-50 ng/mL were higher than 87%. Copyright © 2011 Elsevier B.V. All rights reserved.

Improving the light-emitting properties of single-layered polyfluorene light-emitting devices by simple ionic liquid blending

NASA Astrophysics Data System (ADS)

Horike, Shohei; Nagaki, Hiroto; Misaki, Masahiro; Koshiba, Yasuko; Morimoto, Masahiro; Fukushima, Tatsuya; Ishida, Kenji

2018-03-01

This paper describes an evaluation of ionic liquids (ILs) as potential electrolytes for single-layered light-emitting devices with good emission performance. As optoelectronic devices continue to grow in abundance, high-performance light-emitting devices with a single emission layer are becoming increasingly important for low-cost production. We show that a simple technique of osmosing IL into the polymer layer can result in high luminous efficiency and good response times of single-layered light-emitting polymers, even without the additional stacking of charge carrier injection and transport layers. The IL contributions to the light-emission of the polymer are discussed from the perspectives of energy diagrams and of the electric double layers on the electrodes. Our findings enable a faster, cheaper, and lower-in-waste production of light-emitting devices.

Determination of diflubenzuron and chlorbenzuron in fruits by combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

PubMed

Ruan, Chunqiang; Zhao, Xiang; Liu, Chenglan

2015-09-01

In this study, a simple and low-organic-solvent-consuming method combining an acetonitrile-partitioning extraction procedure followed by "quick, easy, cheap, effective, rugged and safe" cleanup with ionic-liquid-based dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection was developed for the determination of diflubenzuron and chlorbenzuron in grapes and pears. Ionic-liquid-based dispersive liquid-liquid microextraction was performed using the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate as the extractive solvent and acetonitrile extract as the dispersive solvent. The main factors influencing the efficiency of the dispersive liquid-liquid microextraction were evaluated, including the extractive solvent type and volume and the dispersive solvent volume. The validation parameters indicated the suitability of the method for routine analyses of benzoylurea insecticides in a large number of samples. The relative recoveries at three spiked levels ranged between 98.6 and 109.3% with relative standard deviations of less than 5.2%. The limit of detection was 0.005 mg/kg for the two insecticides. The proposed method was successfully used for the rapid determination of diflubenzuron and chlorbenzuron residues in real fruit samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-resolution mapping of molecules in an ionic liquid via scanning transmission electron microscopy.

PubMed

Miyata, Tomohiro; Mizoguchi, Teruyasu

2018-03-01

Understanding structures and spatial distributions of molecules in liquid phases is crucial for the control of liquid properties and to develop efficient liquid-phase processes. Here, real-space mapping of molecular distributions in a liquid was performed. Specifically, the ionic liquid 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C2mimTFSI) was imaged using atomic-resolution scanning transmission electron microscopy. Simulations revealed network-like bright regions in the images that were attributed to the TFSI- anion, with minimal contributions from the C2mim+ cation. Simple visualization of the TFSI- distribution in the liquid sample was achieved by binarizing the experimental image.

Dense simple plasmas as high-temperature liquid simple metals

NASA Technical Reports Server (NTRS)

Perrot, F.

1990-01-01

The thermodynamic properties of dense plasmas considered as high-temperature liquid metals are studied. An attempt is made to show that the neutral pseudoatom picture of liquid simple metals may be extended for describing plasmas in ranges of densities and temperatures where their electronic structure remains 'simple'. The primary features of the model when applied to plasmas include the temperature-dependent self-consistent calculation of the electron charge density and the determination of a density and temperature-dependent ionization state.

Rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection.

PubMed

Yang, Xiao; Diao, Chun-Peng; Sun, Ai-Ling; Liu, Ren-Min

2014-10-01

A method for the rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection was proposed in this paper. A simple apparatus consisting of a test tube and a cut-glass dropper was designed and applied to collect the floating extraction drop in liquid-liquid microextraction when low-density organic solvent was used as the extraction solvent. Solidification and melting steps that were tedious but necessary once the low-density organic solvent used as extraction solvent could be avoided by using this apparatus. Bisphenol A was selected as model pollutant and vortex-assisted liquid-liquid microextraction was employed to investigate the usefulness of the apparatus. High-performance liquid chromatography with fluorescence detection was selected as the analytical tool for the detection of bisphenol A. The linear dynamic range was from 0.10 to 100 μg/L for bisphenol A, with good squared regression coefficient (r(2) = 0.9990). The relative standard deviation (n = 7) was 4.7% and the limit of detection was 0.02 μg/L. The proposed method had been applied to the determination of bisphenol A in natural water samples and was shown to be economical, fast, and convenient. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-performance liquid chromatographic determination of loxoprofen and its diastereomeric alcohol metabolites in biological fluids by fluorescence labelling with 4-bromomethyl-6,7-methylenedioxycoumarin.

PubMed

Naganuma, H; Kawahara, Y

1990-09-14

A simple and sensitive high-performance liquid chromatographic procedure to determine loxoprofen and its diastereomeric alcohol metabolites in biological specimens is described. The analysis involves liquid-liquid extraction with benzene, pre-column derivatization with a highly fluorogenic reagent, 4-bromomethyl-6,7-methylenedioxycoumarin (BrMDC) and subsequent separation on a reversed-phase column. Loxoprofen, its pharmacologically active metabolite, trans-alcohol, and less active cis-alcohol were completely separated within 20 min with a mobile phase of 55% of aqueous acetonitrile containing acetic acid. Any endogenous substances do not interfere in the analysis of either plasma or urine samples. The quantitation limit was 0.01 micrograms/ml for human plasma and 0.05 micrograms/ml for urine. The method was applied to a pharmacokinetic study in healthy human subjects who had received 60 mg of loxoprofen sodium.

Simple and robust resistive dual-axis accelerometer using a liquid metal droplet

NASA Astrophysics Data System (ADS)

Huh, Myoung; Won, Dong-Joon; Kim, Joong Gil; Kim, Joonwon

2017-12-01

This paper presents a novel dual-axis accelerometer that consists of a liquid metal droplet in a cone-shaped channel and an electrode layer with four Nichrome electrodes. The sensor uses the advantages of the liquid metal droplet (i.e., high surface tension, electrical conductivity, high density, and deformability). The cone-shaped channel imposes a restoring force on the liquid metal droplet. We conducted simulation tests to determine the appropriate design specifications of the cone-shaped channel. Surface modifications to the channel enhanced the nonwetting performance of the liquid metal droplet. The performances of the sensor were analyzed by a tilting test. When the acceleration was applied along the axial direction, the device showed 6 kΩ/g of sensitivity and negligible crosstalk between the X- and Y-axes. In a diagonal direction test, the device showed 4 kΩ/g of sensitivity.

Preparative isolation and characterization of some minor impurities of astaxanthin by high-performance liquid chromatography.

PubMed

Rao, R Nageswara; Alvi, S Naseeruddin; Rao, B Nageswara

2005-05-27

A simple and rapid preparative high-performance liquid chromatography (HPLC) method has been developed to isolate and characterize some minor impurities of astaxanthin using a normal-phase Lichrosorb silica column with n-hexane-acetone-tetrahydrofuran (90:2:8, v/v/v) as mobile-phase and detection at 475 nm. The isolated impurities were characterized as astacene, dehydro astacene and apoastaxanthinal by UV-vis, ESI-MS, 1H and 13C NMR spectroscopy and the molecular structures were assigned. The impurities collected using the developed conditions were over 98% pure.

Simultaneous determination of phenytoin, carbamazepine, and 10,11-carbamazepine epoxide in human plasma by high-performance liquid chromatography with ultraviolet detection.

PubMed

Bhatti, M M; Hanson, G D; Schultz, L

1998-03-01

The Bioanalytical Chemistry Department at the Madison facility of Covance Laboratories, has developed and validated a simple and sensitive method for the simultaneous determination of phenytoin (PHT), carbamazepine (CBZ) and 10,11-carbamazepine epoxide (CBZ-E) in human plasma by high-performance liquid chromatography with 10,11 dihydrocarbamazepine as the internal standard. Acetonitrile was added to plasma samples containing PHT, CBZ and CBZ-E to precipitate the plasma proteins. After centrifugation, the acetonitrile supernatant was transferred to a clean tube and evaporated under N2. The dried sample extract was reconstituted in 0.4 ml of mobile phase and injected for analysis by high-performance liquid chromatography. Separation was achieved on a Spherisorb ODS2 analytical column with a mobile phase of 18:18:70 acetonitrile:methanol:potassium phosphate buffer. Detection was at 210 nm using an ultraviolet detector. The mean retention times of CBZ-E, PHT and CBZ were 5.8, 9.9 and 11.8 min, respectively. Peak height ratios were fit to a least squares linear regression algorithm with a 1/(concentration)2 weighting. The method produces acceptable linearity, precision and accuracy to a minimum concentration of 0.050 micrograms ml-1 in human plasma. It is also simple and convenient, with no observable matrix interferences.

Ionic liquid-based air-assisted liquid-liquid microextraction followed by high performance liquid chromatography for the determination of five fungicides in juice samples.

PubMed

You, Xiangwei; Chen, Xiaochu; Liu, Fengmao; Hou, Fan; Li, Yiqiang

2018-01-15

A novel and simple ionic liquid-based air-assisted liquid-liquid microextraction technique combined with high performance liquid chromatography was developed to analyze five fungicides in juice samples. In this method, ionic liquid was used instead of a volatile organic solvent as the extraction solvent. The emulsion was formed by pulling in and pushing out the mixture of aqueous sample solution and extraction solvent repeatedly using a 10mL glass syringe. No organic dispersive solvent was required. Under the optimized conditions, the limits of detection (LODs) were 0.4-1.8μgL -1 at a signal-to-noise ratio of 3. The limits of quantification (LOQs) set as the lowest spiking levels with acceptable recovery in juices were 10μgL -1 , except for fludioxonil whose LOQ was 20μgL -1 . The proposed method was applied to determine the target fungicides in juice samples, and acceptable recoveries ranging from 74.9% to 115.4% were achieved. Copyright © 2017. Published by Elsevier Ltd.

Simultaneous determination of the HIV nucleoside analogue reverse transcriptase inhibitors lamivudine, didanosine, stavudine, zidovudine and abacavir in human plasma by reversed phase high performance liquid chromatography.

PubMed

Verweij-van Wissen, C P W G M; Aarnoutse, R E; Burger, D M

2005-02-25

A reversed phase high performance liquid chromatography method was developed for the simultaneous quantitative determination of the nucleoside reverse transcriptase inhibitors (NRTIs) lamivudine, didanosine, stavudine, zidovudine and abacavir in plasma. The method involved solid-phase extraction with Oasis MAX cartridges from plasma, followed by high performance liquid chromatography with a SymmetryShield RP 18 column and ultraviolet detection set at a wavelength of 260 nm. The assay was validated over the concentration range of 0.015-5 mg/l for all five NRTIs. The average accuracies for the assay were 92-102%, inter- and intra-day coefficients of variation (CV) were <2.5% and extraction recoveries were higher than 97%. This method proved to be simple, accurate and precise, and is currently in use in our laboratory for the quantitative analysis of NRTIs in plasma.

Evaluation and application of microwave-assisted extraction and dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for the determination of polar heterocyclic aromatic amines in hamburger patties.

PubMed

Aeenehvand, Saeed; Toudehrousta, Zahra; Kamankesh, Marzieh; Mashayekh, Morteza; Tavakoli, Hamid Reza; Mohammadi, Abdorreza

2016-01-01

This study developed an analytical method based on microwave-assisted extraction and dispersive liquid-liquid microextraction followed by high-performance liquid chromatography for the determination of three polar heterocyclic aromatic amines from hamburger patties. Effective parameters controlling the performance of the microextraction process, such as the type and volume of extraction and disperser solvents, microwave time, nature of alkaline aqueous solution, pH and salt amount, were optimized. The calibration graphs were linear in the range of 1-200 ng g(-1), with a coefficient of determination (R(2)) better than 0.9993. The relative standard deviations (RSD) for seven analyses were between 3.2% and 6.5%. The recoveries of those compounds in hamburger patties were from 90% to 105%. Detection limits were between 0.06 and 0.21 ng g(-1). A comparison of the proposed method with the existing literature demonstrates that it is a simple, rapid, highly selective and sensitive, and it gives good enrichment factors and detection limits for determining HAAs in real hamburger patties samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

Highly sensitive reversed-phase high-performance liquid chromatography assay for the detection of Tamm-Horsfall protein in human urine.

PubMed

Akimoto, Masaru; Hokazono, Eisaku; Ota, Eri; Tateishi, Takiko; Kayamori, Yuzo

2016-01-01

Tamm-Horsfall protein (also known as uromodulin) is the most abundant urinary protein in healthy individuals. Since initially characterized by Tamm and Horsfall, the amount of urinary excretion and structural mutations of Tamm-Horsfall protein is associated with kidney diseases. However, currently available assays for Tamm-Horsfall protein, which are mainly enzyme-linked immunosorbent assay-based, suffer from poor reproducibility and might give false negative results. We developed a novel, quantitative assay for Tamm-Horsfall protein using reversed-phase high-performance liquid chromatography. A precipitation pretreatment avoided urine matrix interference and excessive sample dilution. High-performance liquid chromatography optimization based on polarity allowed excellent separation of Tamm-Horsfall protein from other major urine components. Our method exhibited high precision (based on the relative standard deviations of intraday [≤2.77%] and interday [≤5.35%] repetitions). The Tamm-Horsfall protein recovery rate was 100.0-104.2%. The mean Tamm-Horsfall protein concentration in 25 healthy individuals was 31.6 ± 18.8 mg/g creatinine. There was a strong correlation between data obtained by high-performance liquid chromatography and enzyme-linked immunosorbent assay (r = 0.906), but enzyme-linked immunosorbent assay values tended to be lower than high-performance liquid chromatography values at low Tamm-Horsfall protein concentrations. The high sensitivity and reproducibility of our Tamm-Horsfall protein assay will reduce the number of false negative results of the sample compared with enzyme-linked immunosorbent assay. Moreover, our method is superior to other high-performance liquid chromatography methods, and a simple protocol will facilitate further research on the physiological role of Tamm-Horsfall protein. © The Author(s) 2015.

Ionic liquids and ionic liquid acids with high temperature stability for fuel cell and other high temperature applications, method of making and cell employing same

DOEpatents

Angell, C Austen [Mesa, AZ; Xu, Wu [Broadview Heights, OH; Belieres, Jean-Philippe [Chandler, AZ; Yoshizawa, Masahiro [Tokyo, JP

2011-01-11

Disclosed are developments in high temperature fuel cells including ionic liquids with high temperature stability and the storage of inorganic acids as di-anion salts of low volatility. The formation of ionically conducting liquids of this type having conductivities of unprecedented magnitude for non-aqueous systems is described. The stability of the di-anion configuration is shown to play a role in the high performance of the non-corrosive proton-transfer ionic liquids as high temperature fuel cell electrolytes. Performance of simple H.sub.2(g) electrolyte/O.sub.2(g) fuel cells with the new electrolytes is described. Superior performance both at ambient temperature and temperatures up to and above 200.degree. C. are achieved. Both neutral proton transfer salts and the acid salts with HSO.sup.-.sub.4 anions, give good results, the bisulphate case being particularly good at low temperatures and very high temperatures. The performance of all electrolytes is improved by the addition of a small amount of involatile base of pK.sub.a value intermediate between those of the acid and base that make the bulk electrolyte. The preferred case is the imidazole-doped ethylammonium hydrogensulfate which yields behavior superior in all respects to that of the industry standard phosphoric acid electrolyte.

Rapid determination of triclosan in personal care products using new in-tube based ultrasound-assisted salt-induced liquid-liquid microextraction coupled with high performance liquid chromatography-ultraviolet detection.

PubMed

Chen, Ming-Jen; Liu, Ya-Ting; Lin, Chiao-Wen; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

2013-03-12

This paper describes the development of a novel, simple and efficient in-tube based ultrasound-assisted salt-induced liquid-liquid microextraction (IT-USA-SI-LLME) technique for the rapid determination of triclosan (TCS) in personal care products by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. IT-USA-SI-LLME method is based on the rapid phase separation of water-miscible organic solvent from the aqueous phase in the presence of high concentration of salt (salting-out phenomena) under ultrasonication. In the present work, an indigenously fabricated home-made glass extraction device (8-mL glass tube inbuilt with a self-scaled capillary tip) was utilized as the phase separation device for USA-SI-LLME. After the extraction, the upper extractant layer was narrowed into the self-scaled capillary tip by pushing the plunger plug; thus, the collection and measurement of the upper organic solvent layer was simple and convenient. The effects of various parameters on the extraction efficiency were thoroughly evaluated and optimized. Under optimal conditions, detection was linear in the concentration range of 0.4-100ngmL(-1) with correlation coefficient of 0.9968. The limit of detection was 0.09ngmL(-1) and the relative standard deviations ranged between 0.8 and 5.3% (n=5). The applicability of the developed method was demonstrated for the analysis of TCS in different commercial personal care products and the relative recoveries ranged from 90.4 to 98.5%. The present method was proven to be a simple, sensitive, less organic solvent consuming, inexpensive and rapid procedure for analysis of TCS in a variety of commercially available personal care products or cosmetic preparations. Copyright © 2013 Elsevier B.V. All rights reserved.

Air-assisted liquid-liquid microextraction integrated with QuEChERS for determining endocrine-disrupting compounds in fish by high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Luo, Zhoufei; Lu, Jing; Li, Haipu; Tu, Yi; Wan, Yuehao; Yang, Zhaoguang

2018-09-15

A new, sensitive, and rapid method based on the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) approach and air-assisted liquid-liquid microextraction (AALLME) technology was developed for the determination of 20 endocrine-disrupting compounds (EDCs) in fish by high-performance liquid chromatography-tandem mass spectrometry. The method first integrates AALLME into QuEChERS to achieve clean-up and enrichment of the EDCs in one step. A self-made glass tube was enfolded with plasticine to withstand the high centrifugal force. The established method was developed by optimization of the parameters. High linearities (R 2  > 0.9924) and recoveries (78.2-118.6%) at three spiked levels (5, 10, and 20 ng g -1 ), and low relative standard deviation values (1.1-14.5%) and limits of detection (0.03-0.80 ng g -1 ) were obtained. The method comparison shows that the proposed method is superior as it involves less organic solvent usage, simple operation and high efficiency. This method was successfully applied to different fishes for analyzing EDCs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Rapid determination of nitrite in foods in acidic conditions by high-performance liquid chromatography with fluorescence detection.

PubMed

Wang, Xiao-Fang; Fan, Ji-Cai; Ren, Ren; Jin, Quan; Wang, Jing

2016-06-01

In this study, a simple, rapid, and sensitive method for the determination of nitrite (NO2 (-) ) in food samples by high-performance liquid chromatography with fluorescence detection in acidic conditions had been developed. The derivatization of the nitrite with 2,3-diaminonaphthalene was performed in acidic conditions to yield the highly fluorescent 2,3-naphthotriazole, which was directly analyzed by high-performance liquid chromatography with fluorescence detection without adjusting the solution to alkaline. The analysis column was reversed-phase C8 column. A constant flow rate of 1.0 mL/min was employed using water/acetonitrile as the mobile phase in isocratic mode (70:30, v/v). Fluorescence was monitored with excitation at 375 nm and emission at 415 nm. The standard calibration curves were linear for nitrite in different matrixes in the concentration range of 0-100 μg/L, and the correlation coefficients ranged from 0.9978 to 0.9998. The limits of detection and quantification were in the ranges of 0.012-0.060 and 0.040-0.20 mg/kg, respectively. The recoveries of nitrite from samples spiked at three different concentrations were 74.0-113.2%, and the relative standard deviations of the recovery results (n = 6) were 1.67-10.8%. The proposed method has good repeatability and is very sensitive and simple. It has been successfully used to determine nitrite in foods. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid quantification of iodopropynyl butylcarbamate as the preservative in cosmetic formulations using high-performance liquid chromatography-electrospray mass spectrometry.

PubMed

Frauen, M; Steinhart, H; Rapp, C; Hintze, U

2001-07-01

A simple, rapid and reproducible method for identification and quantification of iodopropynyl butylcarbamate (IPBC) in different cosmetic formulations is presented. The determination was carried out using a high-performance liquid chromatography (HPLC) procedure on a reversed phase column coupled to a single quadrupole mass spectrometer (MS) via an electrospray ionization (ESI) interface. Detection was performed in the positive selected ion-monitoring mode. In methanol/water extracts from different cosmetic formulations a detection limit between 50 and 100 ng/g could be achieved. A routine analytical procedure could be set up with good quantification reliability (relative standard deviation between 0.9 and 2.9%).

A simple high performance liquid chromatography method for analyzing paraquat in soil solution samples.

PubMed

Ouyang, Ying; Mansell, Robert S; Nkedi-Kizza, Peter

2004-01-01

A high performance liquid chromatography (HPLC) method with UV detection was developed to analyze paraquat (1,1'-dimethyl-4,4'-dipyridinium dichloride) herbicide content in soil solution samples. The analytical method was compared with the liquid scintillation counting (LSC) method using 14C-paraquat. Agreement obtained between the two methods was reasonable. However, the detection limit for paraquat analysis was 0.5 mg L(-1) by the HPLC method and 0.05 mg L(-1) by the LSC method. The LSC method was, therefore, 10 times more precise than the HPLC method for solution concentrations less than 1 mg L(-1). In spite of the high detection limit, the UC (nonradioactive) HPLC method provides an inexpensive and environmentally safe means for determining paraquat concentration in soil solution compared with the 14C-LSC method.

A simple modern correctness condition for a space-based high-performance multiprocessor

NASA Technical Reports Server (NTRS)

Probst, David K.; Li, Hon F.

1992-01-01

A number of U.S. national programs, including space-based detection of ballistic missile launches, envisage putting significant computing power into space. Given sufficient progress in low-power VLSI, multichip-module packaging and liquid-cooling technologies, we will see design of high-performance multiprocessors for individual satellites. In very high speed implementations, performance depends critically on tolerating large latencies in interprocessor communication; without latency tolerance, performance is limited by the vastly differing time scales in processor and data-memory modules, including interconnect times. The modern approach to tolerating remote-communication cost in scalable, shared-memory multiprocessors is to use a multithreaded architecture, and alter the semantics of shared memory slightly, at the price of forcing the programmer either to reason about program correctness in a relaxed consistency model or to agree to program in a constrained style. The literature on multiprocessor correctness conditions has become increasingly complex, and sometimes confusing, which may hinder its practical application. We propose a simple modern correctness condition for a high-performance, shared-memory multiprocessor; the correctness condition is based on a simple interface between the multiprocessor architecture and a high-performance, shared-memory multiprocessor; the correctness condition is based on a simple interface between the multiprocessor architecture and the parallel programming system.

Determination of sulfonamides in butter samples by ionic liquid magnetic bar liquid-phase microextraction high-performance liquid chromatography.

PubMed

Wu, Lijie; Song, Ying; Hu, Mingzhu; Xu, Xu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

2015-01-01

A novel, simple, and environmentally friendly pretreatment method, ionic liquid magnetic bar liquid-phase microextraction, was developed for the determination of sulfonamides in butter samples by high-performance liquid chromatography. The ionic liquid magnetic bar was prepared by inserting a stainless steel wire into the hollow of a hollow fiber and immobilizing ionic liquid in the micropores of the hollow fiber. In the extraction process, the ionic liquid magnetic bars were used to stir the mixture of sample and extraction solvent and enrich the sulfonamides in the mixture. After extraction, the analyte-adsorbed ionic liquid magnetic bars were readily isolated with a magnet from the extraction system. It is notable that the present method was environmentally friendly since water and only several microliters of ionic liquid were used in the whole extraction process. Several parameters affecting the extraction efficiency were investigated and optimized, including the type of ionic liquid, sample-to-extraction solvent ratio, the number of ionic liquid magnetic bars, extraction temperature, extraction time, salt concentration, stirring speed, pH of the extraction solvent, and desorption conditions. The recoveries were in the range of 73.25-103.85 % and the relative standard deviations were lower than 6.84 %. The experiment results indicated that the present method was effective for the extraction of sulfonamides in high-fat content samples.

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.

An evaluation of sucrose as a possible contaminant in e-liquids for electronic cigarettes by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

PubMed

Kubica, Paweł; Wasik, Andrzej; Kot-Wasik, Agata; Namieśnik, Jacek

2014-05-01

The influence of sucrose combustion products on smoking and nicotine addiction is still controversial because the presence of the sucrose may be treated as a source of aldehydes and organic acids. In e-liquids used as refills for electronic cigarettes, which are made primarily of poly(propylene glycol), glycerine and ethanol, sucrose may be present at trace levels, and its impact on mainstream smoke formation, and hence on human health and smoking/nicotine addiction is unknown. An analytical method was developed where high-performance liquid chromatography in hydrophilic interaction liquid chromatography mode and tandem mass spectrometry were used for fast and simple determination of sucrose and other saccharides in e-liquids for electronic cigarettes. Minimal effort was required in the sample preparation step, and satisfactory results were obtained, and the sample matrix had an insignificant impact. The chromatographic separation was done using an Ascentis Express OH5 column (150 mm × 2.1 mm, 2.7 μm). The coefficients of variation for within-day precision for three concentrations were 2.4 %, 1.6 % and 2.3 %, and the between-day coefficients of variation for a single concentration were 2.1 %, 2.5 % and 1.7 % measured on the next 3 days. The detection limit was 0.73 μg/g, and the sucrose content in e-liquids ranged from 0.76 to 72.93 μg/g among 37 samples. Moreover, with the method presented it is possible to determine the presence of other saccharides such as fructose, glucose, maltose and lactose. However, only sucrose was found in all samples of e-liquids. The proposed method is rapid, simple and reliable in terms of high-performance liquid chromatography coupled with tandem mass spectrometry.

A simple liquid extraction protocol for overcoming the ion suppression of triacylglycerols by phospholipids in liquid chromatography mass spectrometry studies.

PubMed

Araujo, Pedro; Tilahun, Ephrem; Breivik, Joar Fjørtoft; Abdulkader, Bashir M; Frøyland, Livar; Zeng, Yingxu

2016-02-01

It is well-known that triacylglycerol (TAG) ions are suppressed by phospholipid (PL) ions in regiospecific analysis of TAG by mass spectrometry (MS). Hence, it is essential to remove the PL during sample preparation prior to MS analysis. The present article proposes a cost-effective liquid-liquid extraction (LLE) method to remove PL from TAG in different kinds of biological samples by using methanol, hexane and water. High performance thin layer chromatography confirmed the lack of PL in krill oil and salmon liver samples, submitted to the proposed LLE protocol, and liquid chromatography tandem MS confirmed that the identified TAG ions were highly enhanced after implementing the LLE procedure. Copyright © 2015 Elsevier B.V. All rights reserved.

A low voltage submillisecond-response polymer network liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Sun, Jie; Wu, Shin-Tson; Haseba, Yasuhiro

2014-01-01

We report a low voltage and highly transparent polymer network liquid crystal (PNLC) with submillisecond response time. By employing a large dielectric anisotropy LC host JC-BP07N, we have lowered the V2π voltage to 23 V at λ = 514 nm. This will enable PNLC to be integrated with a high resolution liquid-crystal-on-silicon spatial light modulator, in which the maximum voltage is 24 V. A simple model correlating PNLC performance with its host LC is proposed and validated experimentally. By optimizing the domain size, we can achieve V2π < 15 V with some compromises in scattering and response time.

Liquid lens driven by elastomer actuator

NASA Astrophysics Data System (ADS)

Jin, Boya; Lee, Ji-Hyeon; Zhou, Zuowei; Lee, Gi-Bbeum; Ren, Hongwen; Nah, Changwoon

2015-09-01

By filling a liquid droplet in the hole of a dielectric elastomer (DE) film directly, we prepared two small liquid lenses. The aperture of one lens is macro size and the other is micro size. The liquid droplet in each hole of the DE film exhibits a lens character due to its biconvex shape. In relaxed state, the focal length of each liquid droplet is the longest. When a sufficiently high DC voltage is applied, the diameter of each DE hole is decreased by the generated Maxwell stress, causing the curvature of its droplet to increase. As a result, the focal length of each lens is reduced. Here the DE film functions as an actuator. In contrast to previous approaches, our miniature liquid lenses possess the advantages of simple fabrication, fast response time (~ 540 ms), and high optical performance (~ 114 lp/mm). Moreover, the micro-sized liquid lens presents good mechanical stability.

Highly Stretchable and Transparent Microfluidic Strain Sensors for Monitoring Human Body Motions.

PubMed

Yoon, Sun Geun; Koo, Hyung-Jun; Chang, Suk Tai

2015-12-16

We report a new class of simple microfluidic strain sensors with high stretchability, transparency, sensitivity, and long-term stability with no considerable hysteresis and a fast response to various deformations by combining the merits of microfluidic techniques and ionic liquids. The high optical transparency of the strain sensors was achieved by introducing refractive-index matched ionic liquids into microfluidic networks or channels embedded in an elastomeric matrix. The microfluidic strain sensors offer the outstanding sensor performance under a variety of deformations induced by stretching, bending, pressing, and twisting of the microfluidic strain sensors. The principle of our microfluidic strain sensor is explained by a theoretical model based on the elastic channel deformation. In order to demonstrate its capability of practical usage, the simple-structured microfluidic strain sensors were performed onto a finger, wrist, and arm. The highly stretchable and transparent microfluidic strain sensors were successfully applied as potential platforms for distinctively monitoring a wide range of human body motions in real time. Our novel microfluidic strain sensors show great promise for making future stretchable electronic devices.

Preconcentration and determination of ceftazidime in real samples using dispersive liquid-liquid microextraction and high-performance liquid chromatography with the aid of experimental design.

PubMed

Razmi, Rasoul; Shahpari, Behrouz; Pourbasheer, Eslam; Boustanifar, Mohammad Hasan; Azari, Zhila; Ebadi, Amin

2016-11-01

A rapid and simple method for the extraction and preconcentration of ceftazidime in aqueous samples has been developed using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography analysis. The extraction parameters, such as the volume of extraction solvent and disperser solvent, salt effect, sample volume, centrifuge rate, centrifuge time, extraction time, and temperature in the dispersive liquid-liquid microextraction process, were studied and optimized with the experimental design methods. Firstly, for the preliminary screening of the parameters the taguchi design was used and then, the fractional factorial design was used for significant factors optimization. At the optimum conditions, the calibration curves for ceftazidime indicated good linearity over the range of 0.001-10 μg/mL with correlation coefficients higher than the 0.98, and the limits of detection were 0.13 and 0.17 ng/mL, for water and urine samples, respectively. The proposed method successfully employed to determine ceftazidime in water and urine samples and good agreement between the experimental data and predictive values has been achieved. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of Fusarium toxins in functional vegetable milks applying salting-out-assisted liquid-liquid extraction combined with ultra-high-performance liquid chromatography tandem mass spectrometry.

PubMed

Hamed, Ahmed M; Arroyo-Manzanares, Natalia; García-Campaña, Ana M; Gámiz-Gracia, Laura

2017-11-01

Vegetable milks are considered as functional foods due to their physiological benefits. Although the consumption of these products has significantly increased, they have received little attention in legislation with regard to contaminants. However, they may contain mycotoxins resulting from the use of contaminated raw materials. In this work, ultra-high-performance liquid chromatography tandem mass spectrometry has been proposed for the determination of the most relevant Fusarium toxins (fumonisin B 1 and B 2 , HT-2 and T-2 toxins, zearalenone, deoxynivalenol and fusarenon-X) in different functional beverages based on cereals, legumes and seeds. Sample treatment consisted of a simple salting-out-assisted liquid-liquid extraction with no further clean-up. The method provided limits of quantification between 3.2 and 57.7 µg L -1 , recoveries above 80% and precision with RSD lower than 12%. The method was also applied for studying the occurrence of these mycotoxins in market samples of vegetable functional beverages and deoxynivalenol was found in three oat-based commercial drinks.

Development of a UHPLC-MS/MS method for the measurement of chlortetracycline degradation in swine manure

USDA-ARS?s Scientific Manuscript database

An ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed capable of simultaneously measuring chlortetracycline (CTC), epi-chlortetracycline (epi-CTC), isochlortetracycline (ICTC), oxytetracycline, and tetracycline in swine manure. A simple sample pr...

Quantitation of silibinin, a putative cancer chemopreventive agent derived from milk thistle (Silybum marianum), in human plasma by high-performance liquid chromatography and identification of possible metabolites.

PubMed

Hoh, Carmen S L; Boocock, David J; Marczylo, Timothy H; Brown, V A; Cai, Hong; Steward, William P; Berry, David P; Gescher, Andreas J

2007-04-04

Silibinin has recently received attention as a potential cancer chemopreventive agent because of its antiproliferative and anticarcinogenic effects. A simple and specific reversed-phase high-performance liquid chromatography method was developed and validated for the quantitation of silibinin in human plasma. Sample preparation involved simple protein precipitation, and separation was achieved on a Waters Atlantis C18 column with flow rate of 1.0 mL/min at 40 degrees C and UV detection at 290 nm. Silibinin was detected as two peaks corresponding to trans-diastereoisomers. The peak area was linear over the investigated concentration range (0-5000 ng/mL). The limits of detection were 2 and 1 ng/mL for the two diastereoisomers (d1 and d2), with a recovery of 53-58%. This method was utilized to detect silibinin in plasma of colorectal patients after 7 days of treatment with silipide (silibinin formulated with phosphatidyl choline).

Application of a rapid and selective method for the simultaneous determination of carebastine and pseudoephedrine in human plasma by liquid chromatography-electrospray mass spectrometry for bioequivalence study in Korean subjects.

PubMed

Lee, Myung-Jae; Lee, Heon-Woo; Kang, Jong-Min; Seo, Ji-Hyung; Tak, Seong-Kun; Shim, Wangseob; Yim, Sung-Vin; Hong, Seung Jae; Lee, Kyung-Tae

2010-10-01

We describe a simple, rapid and sensitive high-performance liquid chromatography-electrospray ionization tandem mass spectrometric method that was developed for the simultaneous determination of carebastine and pseudoephedrine in human plasma using cisapride as an internal standard. Acquisition was performed in multiple-reaction monitoring mode by monitoring the transitions: m/z 500.43 > 167.09 for carebastine and m/z 166.04 > 147.88 for pseudoephedrine. The devised method involves a simple single-step liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on a C(18) reversed-phase chromatographic column at 0.2  mL/min by isocratic elution with 10  mM ammonium formate buffer-acetonitrile (30:70, v/v; adjusted to pH 3.3 with formic acid). The devised method was validated over 0.5-100  ng/mL of carebastine and 5-1000  ng/mL of pseudoephedrine with acceptable accuracy and precision, and was successfully applied to a bioequivalence study involving a single oral dose (10  mg of ebastine plus 120  mg of pseudoephedrine complex) to healthy Korean volunteers. Copyright © 2010 John Wiley & Sons, Ltd.

Determination of dasatinib in the tablet dosage form by ultra high performance liquid chromatography, capillary zone electrophoresis, and sequential injection analysis.

PubMed

Gonzalez, Aroa Garcia; Taraba, Lukáš; Hraníček, Jakub; Kozlík, Petr; Coufal, Pavel

2017-01-01

Dasatinib is a novel oral prescription drug proposed for treating adult patients with chronic myeloid leukemia. Three analytical methods, namely ultra high performance liquid chromatography, capillary zone electrophoresis, and sequential injection analysis, were developed, validated, and compared for determination of the drug in the tablet dosage form. The total analysis time of optimized ultra high performance liquid chromatography and capillary zone electrophoresis methods was 2.0 and 2.2 min, respectively. Direct ultraviolet detection with detection wavelength of 322 nm was employed in both cases. The optimized sequential injection analysis method was based on spectrophotometric detection of dasatinib after a simple colorimetric reaction with folin ciocalteau reagent forming a blue-colored complex with an absorbance maximum at 745 nm. The total analysis time was 2.5 min. The ultra high performance liquid chromatography method provided the lowest detection and quantitation limits and the most precise and accurate results. All three newly developed methods were demonstrated to be specific, linear, sensitive, precise, and accurate, providing results satisfactorily meeting the requirements of the pharmaceutical industry, and can be employed for the routine determination of the active pharmaceutical ingredient in the tablet dosage form. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controllable Synthesis of Formaldehyde Modified Manganese Oxide Based on Gas-Liquid Interfacial Reaction and Its Application of Electrochemical Sensing.

PubMed

Bai, Wushuang; Sheng, Qinglin; Nie, Fei; Zheng, Jianbin

2015-12-30

Controllable synthesis of manganese oxides was performed via a simple one-step synthetic method. Then obtained manganese oxides which exhibit flower-like, cloud-like, hexagon-like, and rod-like morphologies were modified by formaldehyde based on a simple self-made gas-liquid reaction device respectively and the modified manganese oxides with coral-like, scallop-like and rod-like morphology were synthesized accordingly. The obtained materials were characterized and the formation mechanism was also researched. Then the modified manganese oxides were used to fabricate electrochemical sensors to detect H2O2. Comparison of electrochemical properties between three kinds of modified manganese oxides was investigated and the best one has been successfully employed as H2O2 sensor which shows a low detection limit of 0.01 μM, high sensitivity of 162.69 μA mM(-1) cm(-2), and wide linear range of 0.05 μM-12.78 mM. The study provides a new method for controllable synthesis of metal oxides, and electrochemical application of formaldehyde modified manganese oxides will provides a new strategy for electrochemical sensing with high performance, low cost, and simple fabrication.

Application of the desulfurization of phenothiazines for a sensitive detection method by high-performance liquid chromatography.

PubMed

Shimada, K; Mino, T; Nakajima, M; Wakabayashi, H; Yamato, S

1994-11-04

A simple and sensitive high-performance liquid chromatographic (HPLC) method for the determination of phenothiazine (PHE) is described. PHE is converted to diphenylamine (DIP) by desulfurization with Raney nickel catalyst. DIP is highly sensitive to electrochemical detection. The calibration graph for PHE quantification after desulfurization was linear between 0.1 and 2.0 ng per injection. The detection limit (signal-to-noise ratio = 3) of PHE after desulfurization was 10 pg, which is twenty times higher than that of the parent compound PHE. The proposed desulfurization technique was applied to other PHE-related compounds. The structural confirmation of the desulfurized product of PHE was carried out by LC-MS using atmospheric pressure chemical ionization.

[Developments in preparation and experimental method of solid phase microextraction fibers].

PubMed

Yi, Xu; Fu, Yujie

2004-09-01

Solid phase microextraction (SPME) is a simple and effective adsorption and desorption technique, which concentrates volatile or nonvolatile compounds from liquid samples or headspace of samples. SPME is compatible with analyte separation and detection by gas chromatography, high performance liquid chromatography, and other instrumental methods. It can provide many advantages, such as wide linear scale, low solvent and sample consumption, short analytical times, low detection limits, simple apparatus, and so on. The theory of SPME is introduced, which includes equilibrium theory and non-equilibrium theory. The novel development of fiber preparation methods and relative experimental techniques are discussed. In addition to commercial fiber preparation, different newly developed fabrication techniques, such as sol-gel, electronic deposition, carbon-base adsorption, high-temperature epoxy immobilization, are presented. Effects of extraction modes, selection of fiber coating, optimization of operating conditions, method sensitivity and precision, and systematical automation, are taken into considerations in the analytical process of SPME. A simple perspective of SPME is proposed at last.

Simple and sensitive method for quantification of fluorescent enzymatic mature and senescent crosslinks of collagen in bone hydrolysate using single-column high performance liquid chromatography.

PubMed

Viguet-Carrin, S; Gineyts, E; Bertholon, C; Delmas, P D

2009-01-01

A rapid high performance liquid chromatographic method was developed including an internal standard for the measurement of mature and senescent crosslinks concentration in non-demineralized bone hydrolysates. To avoid the demineralization which is a tedious step, we developed a method based on the use of a solid-phase extraction procedure to clean-up the samples. It resulted in sensitive and accurate measurements: the detection limits as low as 0.2 pmol for the pyridimium crosslinks and 0.02 pmol for the pentosidine. The inter- and intra-assay coefficients of variation were as low as 5% and 2%, respectively, for all crosslinks.

[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.

Determination of alpha-hydroxy acids in cosmetic products by high-performance liquid chromatography with a narrow-bore column.

PubMed

Nicoletti, I; Corradini, C; Cogliandro, E; Cavazza, A

1999-08-01

This paper reports the results of a study carried out to develop a simple, rapid and sensitive method for the separation, identification and quantitative measurement of alpha-hydroxy acids in commercial cosmetics using high-performance liquid chromatography (HPLC). This method is successfully applied to the simultaneous identification and quantitative determination of glycolic, lactic, malic, tartaric and citric acids employing a reversed phase narrow-bore column under isocratic condition and UV detection. The method is validated by determining the precision of replicate analyses and accuracy by analyzing samples with and without adding know amount of the alpha-hydroxy acids. The procedure is suitable for routine analyses of commercial cosmetics.

[Determination of glycyrrhizinic acid in biotransformation system by reversed-phase high performance liquid chromatography].

PubMed

Li, Hui; Lu, Dingqiang; Liu, Weimin

2004-05-01

A method for determining glycyrrhizinic acid in the biotransformation system by reversed-phase high performance liquid chromatography (RP-HPLC) was developed. The HPLC conditions were as follows: Hypersil C18 column (4.6 mm i.d. x 250 mm, 5 microm) with a mixture of methanol-water-acetic acid (70:30:1, v/v) as the mobile phase; flow rate at 1.0 mL/min; and UV detection at 254 nm. The linear range of glycyrrhizinic acid was 0.2-20 microg. The recoveries were 98%-103% with relative standard deviations between 0.16% and 1.58% (n = 3). The method is simple, rapid and accurate for determining glycyrrhizinic acid.

High Performance Liquid Chromatography-Diode Array Detector Method for the Simultaneous Determination of Five Compounds in the Pulp and Seed of Sea Buckthorn.

PubMed

Zhao, Lu; Wen, E; Upur, Halmuart; Tian, Shuge

2017-01-01

Sea buckthorn ( Hippophae rhamnoides L.) as a traditional Chinese medicinal plant has various uses in Xinjiang. A reversed-phase rapid-resolution liquid-chromatography method with diode array detector was developed for simultaneous determination of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the pulp and seed of sea buckthorn, a widely used traditional Chinese medicine for promoting metabolism and treating scurvy and other diseases. Compounds were separated on an Agilent ZORBAX SB-C18 column (4.6 mm × 250 mm, 5 μm; USA) with gradient elution using methanol and 0.4% phosphoric acid (v/v) at 1.0 mL/min. Detection wavelength was set at 280 nm. The fruits of wild sea buckthorn were collected from Wushi County in Aksu, Xinjiang Province. The RSD of precision test of the five compounds were in the range of 0.60-2.22%, and the average recoveries ranged from 97.36% to 101.19%. Good linearity between specific chromatographic peak and component qualities were observed in the investigated ranges for all the analytes ( R 2 > 0.9997). The proposed method was successfully applied to determine the levels of five active components in sea buckthorn samples from Aksu in Xinjiang. The proposed method is simple, fast, sensitive, accurate, and suitable for quantitative assessment of the pulp and seed of sea buckthorn. Quantitative analysis method of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the extract of sea buckthorn pulp and seed is developed by high-performance liquid chromatography (HPLC) diode array detection.This method is simple and accurate; has strong specificity, good precision, and high recovery rate; and provides a reliable basis for further development of the substances in the pulp and seed of sea buckthorn.The method is widely used for content determination of active ingredients or physiologically active components in traditional Chinese medicine and its preparation Abbreviation used: PR: protocatechuic acid, RU: rutin, QU: quercetin, KA: kaempferol, IS: isorhamnetin, HPLC: high-performance liquid chromatography, HPLC-DAD: high performance liquid chromatographydiode array detector, LOD: linearity and limit of detection, LOQ: limit of quantitation, RSD: relative standard deviation.

High-Throughput Density Measurement Using Magnetic Levitation.

PubMed

Ge, Shencheng; Wang, Yunzhe; Deshler, Nicolas J; Preston, Daniel J; Whitesides, George M

2018-06-20

This work describes the development of an integrated analytical system that enables high-throughput density measurements of diamagnetic particles (including cells) using magnetic levitation (MagLev), 96-well plates, and a flatbed scanner. MagLev is a simple and useful technique with which to carry out density-based analysis and separation of a broad range of diamagnetic materials with different physical forms (e.g., liquids, solids, gels, pastes, gums, etc.); one major limitation, however, is the capacity to perform high-throughput density measurements. This work addresses this limitation by (i) re-engineering the shape of the magnetic fields so that the MagLev system is compatible with 96-well plates, and (ii) integrating a flatbed scanner (and simple optical components) to carry out imaging of the samples that levitate in the system. The resulting system is compatible with both biological samples (human erythrocytes) and nonbiological samples (simple liquids and solids, such as 3-chlorotoluene, cholesterol crystals, glass beads, copper powder, and polymer beads). The high-throughput capacity of this integrated MagLev system will enable new applications in chemistry (e.g., analysis and separation of materials) and biochemistry (e.g., cellular responses under environmental stresses) in a simple and label-free format on the basis of a universal property of all matter, i.e., density.

Time- and cost-saving apparatus for analytical sample filtration

Treesearch

William R. Kenealy; Joseph C. Destree

2005-01-01

Simple and cost-effective protocols were developed for removing particulates from samples prior to analysis by high performance liquid chromatography and gas chromatography. A filter and vial holder were developed for use with a 96-well filtration plate. The device saves preparation time and costs.

A simple and robust high-performance liquid chromatography coupled to a diode-array detector method for the analysis of genistein in mouse tissues.

PubMed

Tamames-Tabar, C; Imbuluzqueta, E; Campanero, M A; Horcajada, P; Blanco-Prieto, M J

2013-09-15

A simple liquid-liquid extraction procedure and quantification by high-performance liquid chromatography (HPLC) method coupled to a diode-array detector (DAD) of genistein (GEN) was developed in various mouse biological matrices. 7-ethoxycoumarin was used as internal standard (IS) and peaks were optimally separated using a Kinetex C18 column (2.6μm, 150mm×2.10mm I.D.) at 40°C with an isocratic elution of mobile phase with sodium dihydrogen phosphate 0.01M in water at pH 2.5 and methanol (55:45, v/v), at a flow rate of 0.25mL/min. The injection volume was 10μL. In all cases, the range of GEN recovery was higher than 61%. The low limit of quantification (LLOQ) was 25ng/mL. The linearity of the calibration curves was satisfactory in all cases as shown by correlation coefficients >0.996. The within-day and between-day precisions were <15% and the accuracy ranged in all cases between 90.14% and 106.05%. This method was successfully applied to quantify GEN in liver, spleen, kidney and plasma after intravenous administration of a single dose (30mg/kg) in female BALB/C mice. Copyright © 2013 Elsevier B.V. All rights reserved.

Separation of enantiomers of new psychoactive substances by high-performance liquid chromatography.

PubMed

Kadkhodaei, Kian; Forcher, Lisa; Schmid, Martin G

2018-03-01

New psychoactive substances are defined as compounds with consciousness-changing effects and have been developed simultaneously with classical drugs. They arise through structural modifications of illegal substances and are mainly produced to circumvent laws. Availability is simple, since new psychoactive substances can be purchased from the Internet. Among them many chemical drug compound classes are chiral and thus the two resulting enantiomers can differ in their effects. The aim of this study is to develop a suitable chiral high-performance liquid chromatography separation method for a broad spectrum of new psychoactive substances using cellulose tris(3,5-dichlorophenylcarbamate) as a chiral selector. Experiments were performed by high-performance liquid chromatography in normal-phase mode under isocratic conditions using ultraviolet detection. Direct separation was carried out on a high-performance liquid chromatography column (Lux® i-Cellulose-5, 3.5 μm, Phenomenex®), available since 2016. Excellent separation results were obtained for cathinones. After further optimization, even 47 instead of 39 out of 52 cathinones showed baseline separation. For amphetamine derivatives, satisfactory results were not achieved. Further, new psychoactive substances from other compound classes such as benzofuranes, thiophenes, phenidines, phenidates, morpholines, and ketamines were partially resolved, depending on the polarity and degree of substitution. All analytes, which were mainly purchased from the Internet, were proven to be traded as racemates. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A simple, rapid and validated high-performance liquid chromatography method suitable for clinical measurements of human mercaptalbumin and non-mercaptalbumin.

PubMed

Yasukawa, Keiko; Shimosawa, Tatsuo; Okubo, Shigeo; Yatomi, Yutaka

2018-01-01

Background Human mercaptalbumin and human non-mercaptalbumin have been reported as markers for various pathological conditions, such as kidney and liver diseases. These markers play important roles in redox regulations throughout the body. Despite the recognition of these markers in various pathophysiologic conditions, the measurements of human mercaptalbumin and non-mercaptalbumin have not been popular because of the technical complexity and long measurement time of conventional methods. Methods Based on previous reports, we explored the optimal analytical conditions for a high-performance liquid chromatography method using an anion-exchange column packed with a hydrophilic polyvinyl alcohol gel. The method was then validated using performance tests as well as measurements of various patients' serum samples. Results We successfully established a reliable high-performance liquid chromatography method with an analytical time of only 12 min per test. The repeatability (within-day variability) and reproducibility (day-to-day variability) were 0.30% and 0.27% (CV), respectively. A very good correlation was obtained with the results of the conventional method. Conclusions A practical method for the clinical measurement of human mercaptalbumin and non-mercaptalbumin was established. This high-performance liquid chromatography method is expected to be a powerful tool enabling the expansion of clinical usefulness and ensuring the elucidation of the roles of albumin in redox reactions throughout the human body.

Rapid determination of some psychotropic drugs in complex matrices by tandem dispersive liquid-liquid microextraction followed by high performance liquid chromatography.

PubMed

Asghari, Alireza; Fahimi, Ebrahim; Bazregar, Mohammad; Rajabi, Maryam; Boutorabi, Leila

2017-05-01

Simple and rapid determinations of some psychotropic drugs in some pharmaceutical wastewater and human plasma samples were successfully accomplished via the tandem dispersive liquid-liquid microextraction combined with high performance liquid chromatography-ultraviolet detection (TDLLME-HPLC-UV). TDLLME of the three psychotropic drugs clozapine, chlorpromazine, and thioridazine was easily performed through two consecutive dispersive liquid-liquid microextractions. By performing this convenient method, proper sample preconcentrations and clean-ups were achieved in just about 7min. In order to achieve the best extraction efficiency, the effective parameters involved were optimized. The optimal experimental conditions consisted of 100μL of CCl 4 (as the extraction organic solvent), and the pH values of 13 and 2 for the donor and acceptor phases, respectively. Under these optimum experimental conditions, the proposed TDLLME-HPLC-UV technique provided a good linearity in the range of 5-3000ngmL -1 for the three psychotropic drugs with the correlation of determinations (R 2 s) higher than 0.996. The limits of quantification (LOQs) and limits of detection (LODs) obtained were 5.0ngmL -1 and 1.0-1.5ngmL -1 , respectively. Also the proper enrichment factors (EFs) of 96, 99, and 88 for clozapine, chlorpromazine, and thioridazine, respectively, and good extraction repeatabilities (relative standard deviations below 9.3%, n=5) were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of new psychoactive substances in human urine by ultra-high performance supercritical fluid and liquid chromatography: Validation and comparison.

PubMed

Borovcová, Lucie; Pauk, Volodymyr; Lemr, Karel

2018-05-01

New psychoactive substances represent serious social and health problem as tens of new compounds are detected in Europe annually. They often show structural proximity or even isomerism, which complicates their analysis. Two methods based on ultra high performance supercritical fluid chromatography and ultra high performance liquid chromatography with mass spectrometric detection were validated and compared. A simple dilute-filter-and-shoot protocol utilizing propan-2-ol or methanol for supercritical fluid or liquid chromatography, respectively, was proposed to detect and quantify 15 cathinones and phenethylamines in human urine. Both methods offered fast separation (<3 min) and short total analysis time. Precision was well <15% with a few exceptions in liquid chromatography. Limits of detection in urine ranged from 0.01 to 2.3 ng/mL, except for cathinone (5 ng/mL) in supercritical fluid chromatography. Nevertheless, this technique distinguished all analytes including four pairs of isomers, while liquid chromatography was unable to resolve fluoromethcathinone regioisomers. Concerning matrix effects and recoveries, supercritical fluid chromatography produced more uniform results for different compounds and at different concentration levels. This work demonstrates the performance and reliability of supercritical fluid chromatography and corroborates its applicability as an alternative tool for analysis of new psychoactive substances in biological matrixes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous determination of nicotine and cotinine in serum using high-performance liquid chromatography with fluorometric detection and postcolumn UV-photoirradiation system.

PubMed

Yasuda, Makoto; Ota, Tatsuhiro; Morikawa, Atsushi; Mawatari, Ken-ichi; Fukuuchi, Tomoko; Yamaoka, Noriko; Kaneko, Kiyoko; Nakagomi, Kazuya

2013-09-01

A simple and rapid method for the simultaneous determination of serum nicotine and cotinine using high-performance liquid chromatography (HPLC)-fluorometric detection with a postcolumn ultraviolet-photoirradiation system was developed. Analytes were extracted from alkalinized human serum via liquid-liquid extraction using chloroform. The organic phase was back-extracted with the acidified aqueous phase, and the analytes were directly injected into an ion-pair reversed-phase HPLC system. 6-Aminoquinoline was used as an internal standard. Nicotine, cotinine, and 6-aminoquinoline were separated within 14min. The extraction efficiency of nicotine and cotinine was greater than 91%. The linear range was 0.30-1000ng for nicotine and 0.06-1000ng for cotinine. In serum samples from smokers, the concentrations of nicotine and cotinine were 8-15ng/mL and 156-372ng/mL, respectively. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparison of micellar extraction combined with ionic liquid based vortex-assisted liquid-liquid microextraction and modified quick, easy, cheap, effective, rugged, and safe method for the determination of difenoconazole in cowpea.

PubMed

Chen, Xiaochu; Bian, Yanli; Liu, Fengmao; Teng, Peipei; Sun, Pan

2017-10-06

Two simple sample pretreatment for the determination of difenoconazole in cowpea was developed including micellar extraction combined with ionic liquid based vortex-assisted liquid-liquid microextraction (ME-IL-VALLME) prior to high performance liquid chromatography (HPLC), and modified quick, easy, cheap, effective, rugged, and safe method (QuEChERS) coupled with HPLC-MS/MS. In ME-IL-VALLME method, the target analyte was extracted by surfactant Tween 20 micellar solution, then the supernatant was diluted with 3mL water to decrease the solubility of micellar solution. Subsequently, the vortex-assisted liquid-liquid microextraction (VALLME) procedure was performed in the diluted extraction solution by using the ionic liquid of 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM]PF 6 ) as the extraction solvent and Tween 20 as an emulsifier to enhance the dispersion of the water-immiscible ionic liquid into the aqueous phase. Parameters that affect the extraction have been investigated in both methods Under the optimum conditions, the limits of quantitation were 0.10 and 0.05mgkg -1 , respectively. And good linearity was achieved with the correlation coefficient higher than 0.9941. The relative recoveries ranged from 78.6 to 94.8% and 92.0 to 118.0% with the relative standard deviations (RSD) of 7.9-9.6% and 1.2-3.2%, respectively. Both methods were quick, simple and inexpensive. However, the ME-IL-VALLME method provides higher enrichment factor compared with conventional QuEChERS method. The ME-IL-VALLME method has a strong potential for the determination of difenoconazole in complex vegetable matrices with HPLC. Copyright © 2017 Elsevier B.V. All rights reserved.

High-pressure liquid chromatography of aromatic amines

NASA Technical Reports Server (NTRS)

Young, P. R.

1979-01-01

Analysis made on commercially available liquid chromatograph demonstrates high-pressure liquid chromatographic conditions for separation of approximately 50 aromatic amines ranging from simple aniline derivatives to complex multiring di- and tri-amines.

Current and state-of-the-art approaches for detecting mycotoxins in commodities

USDA-ARS?s Scientific Manuscript database

The tools that have been applied to detection of mycotoxins in commodities are numerous and powerful. These include everything from simple to use diagnostic test strips to complex, instrument intensive, methods such as ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS). This wi...

Microfluidic droplet trapping array as nanoliter reactors for gas-liquid chemical reaction.

PubMed

Zhang, Qingquan; Zeng, Shaojiang; Qin, Jianhua; Lin, Bingcheng

2009-09-01

This article presents a simple method for trapping arrays of droplets relying on the designed microstructures of the microfluidic device, and this has been successfully used for parallel gas-liquid chemical reaction. In this approach, the trapping structure is composed of main channel, lateral channel and trapping region. Under a negative pressure, array droplets can be generated and trapped in the microstructure simultaneously, without the use of surfactant and the precise control of the flow velocity. By using a multi-layer microdevice containing the microstructures, single (pH gradient) and multiple gas-liquid reactions (metal ion-NH3 complex reaction) can be performed in array droplets through the transmembrane diffusion of the gas. The droplets with quantitative concentration gradient can be formed by only replacing the specific membrane. The established method is simple, robust and easy to operate, demonstrating the potential of this device for droplet-based high-throughput screening.

2-Naphthalenthiol derivatization followed by dispersive liquid-liquid microextraction as an efficient and sensitive method for determination of acrylamide in bread and biscuit samples using high-performance liquid chromatography.

PubMed

Faraji, Mohammad; Hamdamali, Mohammadrezza; Aryanasab, Fezzeh; Shabanian, Meisam

2018-07-13

In this research, an ultrasonic-assisted extraction followed by 2-naphthalenthiol derivatization and dispersive liquid-liquid microextraction of acrylamide (AA) was developed as simple and sensitive sample preparation method for AA in bread and biscuit samples using high performance liquid chromatography. Influence of derivatization and microextraction parameters were evaluated and optimized. Results showed that the derivatization of AA leads to improve its hydrophobicity and chromatographic behavior. Under optimum conditions of derivatization and microextraction, the method yielded a linear calibration curve ranging from 10 to 1000 μg L -1 with a determination coefficient (R 2 ) of 0.9987. Limit of detection (LOD) and limit of quantification (LOQ) were 3.0 and 9.0 μg L -1 , respectively. Intra-day (n = 6) and inter-day (n = 3) precisions based on relative standard deviation percent (RSD%) for extraction and determination of AA at 50 and 500 μg L -1 levels were less than 9.0%. Finally, the performance of proposed method was investigated for determination of AA in some bread and biscuit samples, and satisfactory results were obtained (relative recovery ≥ 90%). Copyright © 2018. Published by Elsevier B.V.

Tunnel frit: a nonmetallic in-capillary frit for nanoflow ultra high-performance liquid chromatography-mass spectrometryapplications.

PubMed

Chen, Chao-Jung; Chen, Wei-Yun; Tseng, Mei-Chun; Chen, Yet-Ran

2012-01-03

In this study, an easy method to fabricate a durable in-capillary frit was developed for use in nanoflow liquid chromatography (nanoLC). A small orifice was tunneled into the sol-gel frit during the polymerization process resulting in the simple fabrication of a tunnel frit. A short packing tunnel frit column (2 cm, C(18) particles) was able to sustain over 10,000 psi continuous liquid flow for 10 days without observation of particle loss, and back pressure variation was less than 5%. The tunnel frit was successfully applied to the fabrication of nanoflow ultra high-performance liquid chromatography (nano-UHPLC) trap and analytical columns. In the analysis of tryptic peptides, the tunnel frit trap and analytical columns were demonstrated to have high separation efficiency and sensitivity. In analysis of phosphopeptides, the use of the nonmetallic tunnel frit column showed better sensitivity than the metallic frit column. This design can facilitate the preparation of nano-HPLC and nano-UHPLC columns and the packing material can easily be refilled when the column is severely contaminated or clogged. © 2011 American Chemical Society

Liquid-liquid microextraction of synthetic pigments in beverages using a hydrophobic deep eutectic solvent.

PubMed

Zhu, Shuqiang; Zhou, Jia; Jia, Hongfang; Zhang, Haixia

2018-03-15

A method was developed for the determination of eight synthetic pigments in beverage samples by liquid-liquid microextraction followed by high performance liquid chromatography. Using hydrophobic deep eutectic solvent (DES) as the microextraction solvent, several key parameters were optimized, including the type and volume of the hydrophobic DES, pH value, vortex time and salt content. Detection limits were in the range 0.016-1.12 ng/mL, recoveries were in the range 74.5-102.5% and relative standard deviations were <5.4%. The method is simple, green and practical, and could be applied to the extraction and determination of synthetic pigments in beverages. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development and validation of a high-performance liquid chromatography method for determination of cefquinome concentrations in sheep plasma and its application to pharmacokinetic studies.

PubMed

Uney, Kamil; Altan, Feray; Elmas, Muammer

2011-02-01

Cefquinome has a broad spectrum of antibacterial activity and was developed especially for use in animals. A simple and sensitive high-performance liquid chromatography (HPLC) method with UV-visible detection for quantification of cefquinome concentrations in sheep plasma was developed and validated. Separation of cefquinome from plasma components was achieved on a Phenomenex Gemini C(18) column (250 mm by 4.6 mm; internal diameter [i.d.], 5 μm). The mobile phase consisted of acetonitrile and 0.1% trifluoroacetic acid in water and was delivered at a rate of 0.9 ml/min. A simple and rapid sample preparation involved the addition of methanol to 200 μl of plasma to precipitate plasma proteins followed by direct injection of 50 μl of supernatant into the high-performance liquid chromatography system. The linearity range of the proposed method was 0.02 to 12 μg/ml. The intraday and interday coefficients of variation obtained from cefquinome were less than 5%, and biases ranged from -3.76% to 1.24%. Mean recovery based on low-, medium-, and high-quality control standards ranged between 92.0 and 93.9%. Plasma samples were found to be stable in various storage conditions (freeze-thaw, postpreparative, short-term, and long-term stability). The method described was found to be readily available, practicable, cheap, rapid, sensitive, precise, and accurate. It was successfully applied to the study of the pharmacokinetics of cefquinome in sheep. This method can be very useful and an alternate to performing pharmacokinetic studies in the determination of cefquinome for clinical use.

Regioselctive Thiocyanation of Aromatic and Heteroaromatic Compounds Using a Novel Bronsted Acidic Ionic Liquid.

PubMed

Rezayati, Sobhan; Sheikholeslami-Farahani, Fatemeh; Hossaini, Zinatossadat; Hajinasiri, Rahimeh; Abad, Saeid Afshari Sharif

2016-01-01

A convenient procedure for the preparation of 1-(1-Propylsulfonic)-3- methylimidazolium thiocyanate as a novel Brønsted acidic ionic liquid thiocyanation agent and highly efficient heterogeneous catalytic is described. This catalyst is used in regioselective thiocyanation of indoles, anilines, pyrroles and their derivatives (aromatic and heteroaromatic organic compounds) in the presence of H2O2 as a mild and oxidant in EtOH:H2O (1:1 v/v). These reactions are performed under mild and simple conditions and give regioselective products in high yields and short reaction time.

Rapid quantitative analysis of individual anthocyanin content based on high-performance liquid chromatography with diode array detection with the pH differential method.

PubMed

Wang, Huayin

2014-09-01

A new quantitative technique for the simultaneous quantification of the individual anthocyanins based on the pH differential method and high-performance liquid chromatography with diode array detection is proposed in this paper. The six individual anthocyanins (cyanidin 3-glucoside, cyanidin 3-rutinoside, petunidin 3-glucoside, petunidin 3-rutinoside, and malvidin 3-rutinoside) from mulberry (Morus rubra) and Liriope platyphylla were used for demonstration and validation. The elution of anthocyanins was performed using a C18 column with stepwise gradient elution and individual anthocyanins were identified by high-performance liquid chromatography with tandem mass spectrometry. Based on the pH differential method, the high-performance liquid chromatography peak areas of maximum and reference absorption wavelengths of anthocyanin extracts were conducted to quantify individual anthocyanins. The calibration curves for these anthocyanins were linear within the range of 10-5500 mg/L. The correlation coefficients (r(2)) all exceeded 0.9972, and the limits of detection were in the range of 1-4 mg/L at a signal-to-noise ratio ≥5 for these anthocyanins. The proposed quantitative analysis was reproducible with good accuracy of all individual anthocyanins ranging from 96.3 to 104.2% and relative recoveries were in the range 98.4-103.2%. The proposed technique is performed without anthocyanin standards and is a simple, rapid, accurate, and economical method to determine individual anthocyanin contents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance of a Small Gas Generator Using Liquid Hydrogen and Liquid Oxygen

NASA Technical Reports Server (NTRS)

Acker, Loren W.; Fenn, David B.; Dietrich, Marshall W.

1961-01-01

The performance and operating problems of a small hot-gas generator burning liquid hydrogen with liquid oxygen are presented. Two methods of ignition are discussed. Injector and combustion chamber design details based on rocket design criteria are also given. A carefully fabricated showerhead injector of simple design provided a gas generator that yielded combustion efficiencies of 93 and 96 percent.

High Performance Liquid Chromatography-Diode Array Detector Method for the Simultaneous Determination of Five Compounds in the Pulp and Seed of Sea Buckthorn

PubMed Central

Zhao, Lu; Wen, E; Upur, Halmuart; Tian, Shuge

2017-01-01

Context: Sea buckthorn (Hippophae rhamnoides L.) as a traditional Chinese medicinal plant has various uses in Xinjiang. Objective: A reversed-phase rapid-resolution liquid-chromatography method with diode array detector was developed for simultaneous determination of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the pulp and seed of sea buckthorn, a widely used traditional Chinese medicine for promoting metabolism and treating scurvy and other diseases. Settings and design: Compounds were separated on an Agilent ZORBAX SB-C18 column (4.6 mm × 250 mm, 5 μm; USA) with gradient elution using methanol and 0.4% phosphoric acid (v/v) at 1.0 mL/min. Detection wavelength was set at 280 nm. Materials and Methods: The fruits of wild sea buckthorn were collected from Wushi County in Aksu, Xinjiang Province. Statistical performances: The RSD of precision test of the five compounds were in the range of 0.60-2.22%, and the average recoveries ranged from 97.36% to 101.19%. Good linearity between specific chromatographic peak and component qualities were observed in the investigated ranges for all the analytes (R2 > 0.9997). Results: The proposed method was successfully applied to determine the levels of five active components in sea buckthorn samples from Aksu in Xinjiang. Conclusions: The proposed method is simple, fast, sensitive, accurate, and suitable for quantitative assessment of the pulp and seed of sea buckthorn. SUMMARY Quantitative analysis method of protocatechuic acid, rutin, quercetin, kaempferol, and isorhamnetin in the extract of sea buckthorn pulp and seed is developed by high-performance liquid chromatography (HPLC) diode array detection.This method is simple and accurate; has strong specificity, good precision, and high recovery rate; and provides a reliable basis for further development of the substances in the pulp and seed of sea buckthorn.The method is widely used for content determination of active ingredients or physiologically active components in traditional Chinese medicine and its preparation Abbreviation used: PR: protocatechuic acid, RU: rutin, QU: quercetin, KA: kaempferol, IS: isorhamnetin, HPLC: high-performance liquid chromatography, HPLC-DAD: high performance liquid chromatographydiode array detector, LOD: linearity and limit of detection, LOQ: limit of quantitation, RSD: relative standard deviation PMID:28216897

Application of dispersion-solidification liquid-liquid microextraction for the determination of triazole fungicides in environmental water samples by high-performance liquid chromatography.

PubMed

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

2011-01-15

A simple, rapid and environmentally friendly method has been developed for the determination of four triazole fungicides (myclobutanil, tebuconazole, triadimenol, hexaconazole) in water samples by dispersion-solidification liquid-liquid microextraction coupled with high performance liquid chromatography-diode array detection. Several variables that affect the extraction efficiencies, including the type and volume of the extraction solvent and dispersive solvent, extraction time, effect of pH and salt addition, were investigated and optimized. Under the optimum conditions, the proposed method is sensitive and shows a good linearity within a range of 0.5-200 ng mL(-1), with the correlation coefficients (r) varying from 0.9992 to 0.9998. High enrichment factors were achieved ranging from 190 to 450. The recoveries of the target analytes from water samples at spiking levels of 1.0, 5.0 and 50.0 ng mL(-1) were between 84.8% and 110.2%. The limits of detection (LODs) for the analytes were ranged in 0.06-0.1 ng mL(-1), and the relative standard deviations (RSD) varied from 3.9% to 5.7%. The proposed method has been successfully applied for the determination of the triazole fungicides in real water samples. Copyright © 2010 Elsevier B.V. All rights reserved.

Analysis of 6-mercaptopurine in human plasma with a high-performance liquid chromatographic method including post-column derivatization and fluorimetric detection.

PubMed

Jonkers, R E; Oosterhuis, B; ten Berge, R J; van Boxtel, C J

1982-12-10

A relatively simple assay with improved reliability and sensitivity for measuring levels of 6-mercaptopurine in human plasma is presented. After extraction of the compound and the added internal standard with phenyl mercury acetate, samples were separated by ion-pair reversed-phase high-performance liquid chromatography. On-line the analytes were oxidized to fluorescent products and detected in a flow-fluorimeter. The within-day coefficient of variation was 3.8% at a concentration of 25 ng/ml. The lower detection limit was 2 ng/ml when 1.0 ml of plasma was used. Mercaptopurine concentration versus time curves of two subjects after a single oral dose of azathioprine are shown.

Simultaneous quantification of five major active components in capsules of the traditional Chinese medicine ‘Shu-Jin-Zhi-Tong’ by high performance liquid chromatography

PubMed Central

Yang, Xing-Xin; Zhang, Xiao-Xia; Chang, Rui-Miao; Wang, Yan-Wei; Li, Xiao-Ni

2011-01-01

A simple and reliable high performance liquid chromatography (HPLC) method has been developed for the simultaneous quantification of five major bioactive components in ‘Shu-Jin-Zhi-Tong’ capsules (SJZTC), for the purposes of quality control of this commonly prescribed traditional Chinese medicine. Under the optimum conditions, excellent separation was achieved, and the assay was fully validated in terms of linearity, precision, repeatability, stability and accuracy. The validated method was applied successfully to the determination of the five compounds in SJZTC samples from different production batches. The HPLC method can be used as a valid analytical method to evaluate the intrinsic quality of SJZTC. PMID:29403711

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.

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.

High-performance liquid chromatography with fluorescence detection for the rapid analysis of pheophytins and pyropheophytins in virgin olive oil.

PubMed

Li, Xueqi; Woodman, Michael; Wang, Selina C

2015-08-01

Pheophytins and pyropheophytin are degradation products of chlorophyll pigments, and their ratios can be used as a sensitive indicator of stress during the manufacturing and storage of olive oil. They increase over time depending on the storage condition and if the oil is exposed to heat treatments during the refining process. The traditional analysis method includes solvent- and time-consuming steps of solid-phase extraction followed by analysis by high-performance liquid chromatography with ultraviolet detection. We developed an improved dilute/fluorescence method where multi-step sample preparation was replaced by a simple isopropanol dilution before the high-performance liquid chromatography injection. A quaternary solvent gradient method was used to include a fourth strong solvent wash on a quaternary gradient pump, which avoided the need to premix any solvents and greatly reduced the oil residues on the column from previous analysis. This new method not only reduces analysis cost and time but shows reliability, repeatability, and improved sensitivity, especially important for low-level samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alternative solvent-based methyl benzoate vortex-assisted dispersive liquid-liquid microextraction for the high-performance liquid chromatographic determination of benzimidazole fungicides in environmental water samples.

PubMed

Santaladchaiyakit, Yanawath; Srijaranai, Supalax

2014-11-01

Vortex-assisted dispersive liquid-liquid microextraction using methyl benzoate as an alternative extraction solvent for extracting and preconcentrating three benzimidazole fungicides (i.e., carbendazim, thiabendazole, and fluberidazole) in environmental water samples before high-performance liquid chromatographic analysis has been developed. The selected microextraction conditions were 250 μL of methyl benzoate containing 300 μL of ethanol, 1.0% w/v sodium acetate, and vortex agitation speed of 2100 rpm for 30 s. Under optimum conditions, preconcentration factors were 14.5-39.0 for the target fungicides. Limits of detection were obtained in the range of 0.01-0.05 μg/L. The proposed method was then applied to surface water samples and the recovery evaluations at three spiked concentration levels of 5, 30, and 50 μg/L were obtained in the range of 77.4-110.9% with the relative standard deviation <7.4%. The present method was simple, rapid, low cost, sensitive, environmentally friendly, and suitable for the trace analysis of the studied fungicides in environmental water samples. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid determination of parabens in seafood sauces by high-performance liquid chromatography: A practical comparison of core-shell particles and sub-2 μm fully porous particles.

PubMed

Ye, Jing; Cao, Xiaoji; Cheng, Zhuo; Qin, Ye; Lu, Yanbin

2015-12-01

In this work, the chromatographic performance of superficially porous particles (Halo core-shell C18 column, 50 mm × 2.1 mm, 2.7 μm) was compared with that of sub-2 μm fully porous particles (Acquity BEH C18 , 50 mm × 2.1 mm, 1.7 μm). Four parabens, methylparaben, ethylparaben, propylparaben, and butylparaben, were used as representative compounds for calculating the plate heights in a wide flow rate range and analyzed on the basis of the Van Deemter and Knox equations. Theoretical Poppe plots were constructed for each column to compare their kinetic performance. Both phases gave similar minimum plate heights when using nonreduced coordinates. Meanwhile, the flat C-term of the core-shell column provided the possibilities for applying high flow rates without significant loss in efficiency. The low backpressure of core-shell particles allowed this kind of column, especially compatible with conventional high-performance liquid chromatography systems. Based on these factors, a simple high-performance liquid chromatography method was established and validated for the determination of parabens in various seafood sauces using the Halo core-shell C18 column for separation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dispersive liquid-liquid microextraction of phenolic compounds from vegetable oils using a magnetic ionic liquid.

PubMed

Zhu, Shuqiang; Wang, Lijun; Su, Along; Zhang, Haixia

2017-08-01

A novel method was developed for the determination of two endocrine-disrupting chemicals, bisphenol A and 4-nonylphenol, in vegetable oil by dispersive liquid-liquid microextraction followed by ultra high performance liquid chromatography with tandem mass spectrometry. Using a magnetic liquid as the microextraction solvent, several key parameters were optimized, including the type and volume of the magnetic liquid, extraction time, amount of dispersant, and the type of reverse extractant. The detection limits for bisphenol A and 4-nonylphenol were 0.1 and 0.06 μg/kg, respectively. The recoveries were 70.4-112.3%, and the relative standard deviations were less than 4.2%. The method is simple for the extraction of bisphenol A and 4-nonylphenol from vegetable oil and suitable for routine analysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

HPLC of the Polypeptides in a Hydrolyzate of Egg-White Lysozyme. An Experiment for the Undergraduate Biochemistry Laboratory.

ERIC Educational Resources Information Center

Richardson, W. S., III; Burns, L.

1988-01-01

Describes a simple high-performance liquid chromatography experiment for undergraduate biochemistry laboratories. The experiment illustrates the separation of polypeptides by a step gradient elution using a single pump instrument with no gradient attachments. Discusses instrumentation, analysis, a sample preparation, and results. (CW)

Rapid and simple method for the determination of emodin in tartary buckwheat (Fagopyrum tataricum) by high-performance liquid chromatography coupled to a diode array detector.

PubMed

Peng, Lian-Xin; Wang, Jing-Bo; Hu, Li-Xue; Zhao, Jiang-Lin; Xiang, Da-Bing; Zou, Liang; Zhao, Gang

2013-01-30

A simple and rapid method for determining emodin, an active factor presented in tartary buckwheat (Fagopyrum tataricum), by high-performance liquid chromatography coupled to a diode array detector (HPLC-DAD) has been developed. Emodin was separated from an extract of buckwheat on a Kromasil-ODS C(18) (250 mm × 4.6 mm × 5 μm) column. The separation is achieved within 15 min on the ODS column. Emodin can be quantified using an external standard method detecting at 436 nm. Good linearity is obtained with a correlation coefficient exceeding 0.9992. The limit of detection and the limit of quantification are 5.7 and 19 μg/L, respectively. This method shows good reproducibility for the quantification of the emodin with a relative standard deviation value of 4.3%. Under optimized extraction conditions, the recovery of emodin was calculated as >90%. The validated method is successfully applied to quantify the emodin in tartary buckwheat and its products.

A simple quantitative approach for the determination of long and medium chain lipids in bio-relevant matrices by high performance liquid chromatography with refractive index detection.

PubMed

Lee, Kathy Wai Yu; Porter, Christopher J H; Boyd, Ben J

2013-09-01

There is increasing attention in the literature towards understanding the behaviour of lipid-based drug formulations under digestion conditions using in vitro and in vivo methods. This necessitates a convenient method for quantitation of lipids and lipid digestion products. In this study, a simple and accessible method for the separation and quantitative determination of typical formulation and digested lipids using high performance liquid chromatography coupled to refractive index detection (HPLC-RI) is described. Long and medium chain lipids were separated and quantified in a biological matrix (gastrointestinal content) without derivatisation using HPLC-RI on C18 and C8 columns, respectively. The intra- and inter-assay accuracy was between 92% and 106%, and the assays were precise to within a coefficient of variation of less than 10% over the range of 0.1-2 mg/mL for both long and medium chain lipids. This method is also shown to be suitable for quantifying the lipolysis products collected from the gastrointestinal tract in the course of in vivo lipid digestion studies.

[Separation of catechins and caffeine in tea polyphenol by isocratic elution high performance liquid chromatography].

PubMed

Tang, G Y; Wu, H J; Wu, L; Li, Z J; Yao, Y G

2001-05-01

The catechins, particularly in green tea, have been found to possess anti-mutagenic and anti-tumorigenic properties. As each catechin possesses distinct properties, a simple and rapid method that could be used for analysis of individual catechins in a complex mixture would be necessary. A relatively simple and rapid method for simultaneous separation of five catechins and caffeine in tea polyphenol by isocratic elution high performance liquid chromatography has been developed. The analysis could be finished within 30 min. They were measured using Resolve C18 column (at 43 degrees C) and UV detector (at 280 nm), water-85% phosphoric acid aqueous solution-acetonitrile-dimethyl formamide(DMF) (859:1:120:20, V/V) as mobile phase. There was a good linear relationship between the content of component and its peak area for catechins and caffeine, with the correlation coefficients of 0.9992-0.9999. The average recoveries (n = 5) were 83.33%-104.42%, and the relative standard deviations (n = 6) were 0.74%-1.43%. The effect of concentration of DMF in mobile phase was studied.

Simultaneous and rapid determination of deoxynivalenol and its acetylate derivatives in wheat flour and rice by ultra high performance liquid chromatography with photo diode array detection.

PubMed

Xu, Jiao-Jiao; Zhou, Jian; Huang, Bai-Fen; Cai, Zeng-Xuan; Xu, Xiao-Min; Ren, Yi-Ping

2016-06-01

A simple and reliable method of ultra high performance liquid chromatography coupled with photo-diode array detection has been proposed for the simultaneous determination of deoxynivalenol and its acetylated derivatives in wheat flour and rice, especially focusing on the optimization of sample extraction, cleanup, and chromatographic separation conditions. Sample pretreatment consisted of a first step using a quick, easy, cheap, effective, rugged, and safe based extraction procedure and a subsequent cleanup step based on solid-phase extraction. The method was extensively validated in wheat flour and rice, obtaining satisfactory analytical performance with good linearity (R(2) ≥ 0.999), acceptable recoveries (80.0-104.4%), and repeatability (RSDs 1.3-10.7%). The limits of detection (21.7-57.4 μg/kg) and quantitation (72.3-191.4 μg/kg) for deoxynivalenols were lower than those usually permitted by various countries' legislation in these food matrices. The method was applied to 34 wheat and rice samples. The results were further compared with results of ultra high performance liquid chromatography with electrospray ionization tandem mass spectrometry. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development and Validation of a Simple High Performance Liquid Chromatography/UV Method for Simultaneous Determination of Urinary Uric Acid, Hypoxanthine, and Creatinine in Human Urine.

PubMed

Wijemanne, Nimanthi; Soysa, Preethi; Wijesundara, Sulochana; Perera, Hemamali

2018-01-01

Uric acid and hypoxanthine are produced in the catabolism of purine. Abnormal urinary levels of these products are associated with many diseases and therefore it is necessary to have a simple and rapid method to detect them. Hence, we report a simple reverse phase high performance liquid chromatography (HPLC/UV) technique, developed and validated for simultaneous analysis of uric acid, hypoxanthine, and creatinine in human urine. Urine was diluted appropriately and eluted with C-18 column 100 mm × 4.6 mm with a C-18 precolumn 25 mm × 4.6 mm in series. Potassium phosphate buffer (20 mM, pH 7.25) at a flow rate of 0.40 mL/min was employed as the solvent and peaks were detected at 235 nm. Tyrosine was used as the internal standard. The experimental conditions offered a good separation of analytes without interference of endogenous substances. The calibration curves were linear for all test compounds with a regression coefficient, r 2 > 0.99. Uric acid, creatinine, tyrosine, and hypoxanthine were eluted at 5.2, 6.1, 7.2, and 8.3 min, respectively. Intraday and interday variability were less than 4.6% for all the analytes investigated and the recovery ranged from 98 to 102%. The proposed HPLC procedure is a simple, rapid, and low cost method with high accuracy with minimum use of organic solvents. This method was successfully applied for the determination of creatinine, hypoxanthine, and uric acid in human urine.

[Rapid detection of caffeine in blood by freeze-out extraction].

PubMed

Bekhterev, V N; Gavrilova, S N; Kozina, E P; Maslakov, I V

2010-01-01

A new method for the detection of caffeine in blood has been proposed based on the combination of extraction and freezing-out to eliminate the influence of sample matrix. Metrological characteristics of the method are presented. Selectivity of detection is achieved by optimal conditions of analysis by high performance liquid chromatography. The method is technically simple and cost-efficient, it ensures rapid performance of the studies.

A Highly Sensitive Fiber Optic Sensor Based on Two-Core Fiber for Refractive Index Measurement

PubMed Central

Guzmán-Sepúlveda, José Rafael; Guzmán-Cabrera, Rafael; Torres-Cisneros, Miguel; Sánchez-Mondragón, José Javier; May-Arrioja, Daniel Alberto

2013-01-01

A simple and compact fiber optic sensor based on a two-core fiber is demonstrated for high-performance measurements of refractive indices (RI) of liquids. In order to demonstrate the suitability of the proposed sensor to perform high-sensitivity sensing in a variety of applications, the sensor has been used to measure the RI of binary liquid mixtures. Such measurements can accurately determine the salinity of salt water solutions, and detect the water content of adulterated alcoholic beverages. The largest sensitivity of the RI sensor that has been experimentally demonstrated is 3,119 nm per Refractive Index Units (RIU) for the RI range from 1.3160 to 1.3943. On the other hand, our results suggest that the sensitivity can be enhanced up to 3485.67 nm/RIU approximately for the same RI range. PMID:24152878

Application of dispersive liquid-liquid microextraction for the preconcentration of eight parabens in real samples and their determination by high-performance liquid chromatography.

PubMed

Shen, Xiong; Liang, Jian; Zheng, Luxia; Lv, Qianzhou; Wang, Hong

2017-11-01

A simple and sensitive method for the simultaneous determination of eight parabens in human plasma and urine samples was developed. The samples were preconcentrated using dispersive liquid-liquid microextraction based on the solidification of floating organic drops and determined by high-performance liquid chromatography with ultraviolet detection. The influence of variables affecting the extraction efficiency was investigated and optimized using Placket-Burman design and Box-Behnken design. The optimized values were: 58 μL of 1-decanol (as extraction solvent), 0.65 mL methanol (as disperser solvent), 1.5% w/v NaCl in 5.0 mL of sample solution, pH 10.6, and 4.0 min centrifugation at 4000 rpm. The extract was injected into the high-performance liquid chromatography system for analysis. Under the optimum conditions, the linear ranges for eight parabens in plasma and urine were 1.0-1000 ng/mL, with correlation coefficients above 0.994. The limit of detection was 0.2-0.4 and 0.1-0.4 ng/mL for plasma and urine samples, respectively. Relative recoveries were between 80.3 and 110.7%, while relative standard deviations were less than 5.4%. Finally, the method was applied to analyze the parabens in 98 patients of primary breast cancer. Results showed that parabens existed widely, at least one paraben detected in 96.9% (95/98) of plasma samples and 98.0% (96/98) of urine samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of high performance liquid chromatography method for miconazole analysis in powder sample

NASA Astrophysics Data System (ADS)

Hermawan, D.; Suwandri; Sulaeman, U.; Istiqomah, A.; Aboul-Enein, H. Y.

2017-02-01

A simple high performance liquid chromatography (HPLC) method has been developed in this study for the analysis of miconazole, an antifungal drug, in powder sample. The optimized HPLC system using C8 column was achieved using mobile phase composition containing methanol:water (85:15, v/v), a flow rate of 0.8 mL/min, and UV detection at 220 nm. The calibration graph was linear in the range from 10 to 50 mg/L with r 2 of 0.9983. The limit of detection (LOD) and limit of quantitation (LOQ) obtained were 2.24 mg/L and 7.47 mg/L, respectively. The present HPLC method is applicable for the determination of miconazole in the powder sample with a recovery of 101.28 % (RSD = 0.96%, n = 3). The developed HPLC method provides short analysis time, high reproducibility and high sensitivity.

Simple and sensitive analysis of blonanserin and blonanserin C in human plasma by liquid chromatography tandem mass spectrometry and its application.

PubMed

Zheng, Yunliang; Hu, Xingjiang; Liu, Jian; Wu, Guolan; Zhou, Huili; Zhu, Meixiang; Zhai, You; Wu, Lihua; Shentu, Jianzhong

2014-01-01

A highly sensitive, simple, and rapid liquid chromatography tandem mass spectrometry method to simultaneously determine blonanserin and blonanserin C in human plasma with AD-5332 as internal standard (IS) was established. A simple direct protein precipitation method was used for the sample pretreatment, and chromatographic separation was performed on a Waters XBridge C8 (4.6 × 150 mm, 3.5  μ m) column. The mobile phase consists of a mixture of 10 mM ammonium formate and 0.1% formic acid in water (A) and 0.1% formic acid in methanol (B). To quantify blonanserin, blonanserin C, and IS, multiple reaction monitoring (MRM) was performed in positive ESI mode. The calibration curve was linear in the concentration range of 0.012-5.78 ng·mL(-1) for blonanserin and 0.023-11.57 ng·mL(-1) for blonanserin C (r (2) > 0.9990). The intra- and interday precision of three quality control (QC) levels in plasma were less than 7.5%. Finally, the current simple, sensitive, and accurate LC-MS/MS method was successfully applied to investigate the pharmacokinetics of blonanserin and blonanserin C in healthy Chinese volunteers.

Simple and Sensitive Analysis of Blonanserin and Blonanserin C in Human Plasma by Liquid Chromatography Tandem Mass Spectrometry and Its Application

PubMed Central

Zheng, Yunliang; Hu, Xingjiang; Liu, Jian; Wu, Guolan; Zhou, Huili; Zhu, Meixiang; Zhai, You; Wu, Lihua; ShenTu, Jianzhong

2014-01-01

A highly sensitive, simple, and rapid liquid chromatography tandem mass spectrometry method to simultaneously determine blonanserin and blonanserin C in human plasma with AD-5332 as internal standard (IS) was established. A simple direct protein precipitation method was used for the sample pretreatment, and chromatographic separation was performed on a Waters XBridge C8 (4.6 × 150 mm, 3.5 μm) column. The mobile phase consists of a mixture of 10 mM ammonium formate and 0.1% formic acid in water (A) and 0.1% formic acid in methanol (B). To quantify blonanserin, blonanserin C, and IS, multiple reaction monitoring (MRM) was performed in positive ESI mode. The calibration curve was linear in the concentration range of 0.012–5.78 ng·mL−1 for blonanserin and 0.023–11.57 ng·mL−1 for blonanserin C (r 2 > 0.9990). The intra- and interday precision of three quality control (QC) levels in plasma were less than 7.5%. Finally, the current simple, sensitive, and accurate LC-MS/MS method was successfully applied to investigate the pharmacokinetics of blonanserin and blonanserin C in healthy Chinese volunteers. PMID:24678425

Magnetic graphene dispersive solid phase extraction combining high performance liquid chromatography for determination of fluoroquinolones in foods.

PubMed

He, Xin; Wang, Geng Nan; Yang, Kun; Liu, Hui Zhi; Wu, Xia Jun; Wang, Jian Ping

2017-04-15

In this study, a magnetic graphene-based dispersive solid phase extraction method was developed that was combined with high performance liquid chromatography to determine the residues of fluoroquinolone drugs in foods of animal origin. During the experiments, several parameters possible influencing the extraction performance were optimized (amount of magnetic graphene, sample pH, extraction time and elution solution). This extraction method showed high absorption capacities (>6800ng) and high enrichment factors (68-79-fold) for seven fluoroquinolones. Furthermore, this absorbent could be reused for at least 40 times. The limits of detection were in the range of 0.05-0.3ng/g, and the recoveries from the standards fortified blank samples (bovine milk, chicken muscle and egg) were in the range of 82.4-108.5%. Therefore, this method could be used as a simple and sensitive tool to determine the residues of fluoroquinolones in foods of animal origin. Copyright © 2016 Elsevier Ltd. All rights reserved.

Determination of hydroxyaromatic compounds in water by solid-phase microextraction coupled to high-performance liquid chromatography.

PubMed

Wu, Y C; Huang, S D

1999-03-12

Solid-phase microextraction (SPME) coupled with high-performance liquid chromatography (HPLC) for the analysis of hydroxyaromatic compounds is described. Three kinds of fibers [50 microns carbowax-templated resin (CW-TPR), 60 microns polydimethylsiloxane-divinylbenzene (PDMS-DVB) and 85 microns polyacrylate (PA) fibers] were evaluated. CW-TPR and PDMS-DVB were selected for further study. The parameters of the desorption procedure (such as desorption mode, the composition of the solvent for desorption and the duration of fiber soaking) were studied and optimized. The effect of the structure and physical properties of analytes, carryover, duration of absorption, temperature of absorption, pH and ionic strength of samples were also investigated. The method was applied to environmental samples (lake water) using a simple calibration curve.

Isocratic non-aqueous reversed-phase high-performance liquid chromatographic separation of capsanthin and capsorubin in red peppers (Capsicum annuum L.), paprika and oleoresin.

PubMed

Weissenberg, M; Schaeffler, I; Menagem, E; Barzilai, M; Levy, A

1997-01-03

A simple, rapid high-performance liquid chromatography method has been devised in order to separate and quantify the xanthophylls capsorubin and capasanthin present in red pepper (Capsicum annuum L.) fruits and preparations made from them (paprika and oleoresin). A reversed-phase isocratic non-aqueous system allows the separation of xanthophylls within a few minutes, with detection at 450 nm, using methyl red as internal standard to locate the various carotenoids and xanthophylls found in plant extracts. The selection of extraction solvents, mild saponification conditions, and chromatographic features is evaluated and discussed. The method is proposed for rapid screening of large plant populations, plant selection, as well as for paprika products and oleoresin, and also for nutrition and quality control studies.

High-performance liquid chromatographic method optimization for ondansetron assay in extemporaneous topical gel and in marketed products.

PubMed

Quamrun, Masuda; Mamoon, Rashid; Nasheed, Shams; Randy, Mullins

2014-01-01

The compounding and evaluation of ondansetron hydrochloride dihydrate topical gel, 2.5% w/w, were conducted in this study. The gelling agent was Carbopol 940. Ethanol 70% in purified water was used to dissolve the drug and disperse the gelling agent. A gel was formed by adding drops of 0.1 N sodium hydroxide solution. To assay this gel, we developed a simple and reproducible stability--indicating high-performance liquid chromatographic method. This method was validated for specificity, accuracy, and precision. The compounded gel was assayed in triplicate, and the average recovery was 98.3%. Ondansetron marketed products were analyzed for comparison with the compounded formulation. Assay, accuracy, and precision data of the compounded topical gel were comparable to the marketed products.

Simultaneous determination of nitroimidazoles, benzimidazoles, and chloramphenicol components in bovine milk by ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Wang, Yuanyuan; Li, Xiaowei; Zhang, Zhiwen; Ding, Shuangyang; Jiang, Haiyang; Li, Jiancheng; Shen, Jianzhong; Xia, Xi

2016-02-01

A sensitive, confirmatory ultra-high performance liquid chromatography-tandem mass spectrometric method was developed and validated to detect 23 veterinary drugs and metabolites (nitroimidazoles, benzimidazoles, and chloramphenicol components) in bovine milk. Compounds of interest were sequentially extracted from milk with acetonitrile and basified acetonitrile using sodium chloride to induce liquid-liquid partition. The extract was purified on a mixed mode solid-phase extraction cartridge. Using rapid polarity switching in electrospray ionization, a single injection was capable of detecting both positively and negatively charged analytes in a 9 min chromatography run time. Recoveries based on matrix-matched calibrations and isotope labeled internal standards for milk ranged from 51.7% to 101.8%. The detection limits and quantitation limits of the analytical method were found to be within the range of 2-20 ng/kg and 5-50 ng/kg, respectively. The recommended method is simple, specific, and reliable for the routine monitoring of nitroimidazoles, benzimidazoles, and chloramphenicol components in bovine milk samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

Liquid chromatographic determination of florfenicol in the plasma of multiple species of fish

USGS Publications Warehouse

Vue, C.; Schmidt, L.J.; Stehly, G.R.; Gingerich, W.H.

2002-01-01

A simple method was developed for determining florfenicol concentration in a small volume (250 mul) of plasma from five phylogenetically diverse species of freshwater fish. Florfenicol was isolated from the plasma matrix through C-18 solid-phase extraction and quantified by reversed-phase high-performance liquid chromatography with UV detection. The accuracy (84-104%), precision (%RSDless than or equal to8), and sensitivity (quantitation limit <30 ng/ml) of the method indicate its usefulness for conducting pharmacokinetic studies on a variety of freshwater fish. Published by Elsevier Science B.V.

The simple determination method for anthocyanidin aglycones in fruits using ultra-high-performance liquid chromatography.

PubMed

Shim, You-Shin; Yoon, Won-Jin; Kim, Dong-Man; Watanabe, Masaki; Park, Hyun-Jin; Jang, Hae Won; Lee, Jangho; Ha, Jaeho

2015-01-01

The simple determination method for anthocyanidin aglycones in fruits using ultra-high-performance liquid chromatography (UHPLC) coupled with the heating-block acidic hydrolysis method was validated through the precision, accuracy and linearity. The UHPLC separation was performed on a reversed-phase C18 column (particle size 2 μm, i.d. 2 mm, length 100 mm) with a photodiode-array detector. The limits of detection and quantification of the UHPLC analyses were 0.09 and 0.29 mg/kg for delphinidin, 0.08 and 0.24 mg/kg for cyanidin, 0.09 and 0.26 mg/kg for petunidin, 0.14 and 0.42 mg/kg for pelargonidin, 0.16 and 0.48 mg/kg for peonidin and 0.30 and 0.91 mg/kg for malvidin, respectively. The intra- and inter-day precisions of individual anthocyanidin aglycones were <10.3%. All calibration curves exhibited good linearity (r = 0.999) within the tested ranges. The total run time of UHPLC was 8 min. The simple preparation method with UHPLC detection in this study presented herein significantly improved the speed and the simplicity for preparation step of delphinidin, cyanidin, petunidin, pelargonidin, peonidin and malvidin in fruits. Especially, the UHPLC detection exhibited good resolution in spite of shorter run time about four times than conventional HPLC detection. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Determination of organophosphorus pesticides in environmental water samples by dispersive liquid-liquid microextraction with solidification of floating organic droplet followed by high-performance liquid chromatography.

PubMed

Wu, Chunxia; Liu, Huimin; Liu, Weihua; Wu, Qiuhua; Wang, Chun; Wang, Zhi

2010-07-01

A simple dispersive liquid-liquid microextraction based on solidification of floating organic droplet coupled with high-performance liquid chromatography-diode array detection was developed for the determination of five organophosphorus pesticides (OPs) in water samples. In this method, the extraction solvent used is of low density, low toxicity, and proper melting point near room temperature. The extractant droplet could be collected easily by solidifying it in the lower temperature. Some important experimental parameters that affect the extraction efficiencies were optimized. Under the optimum conditions, the calibration curve was linear in the concentration range from 1 to 200 ng mL(-1) for the five OPs (triazophos, parathion, diazinon, phoxim, and parathion-methyl), with the correlation coefficients (r) varying from 0.9991 to 0.9998. High enrichment factors were achieved ranging from 215 to 557. The limits of detection were in the range between 0.1 and 0.3 ng mL(-1). The recoveries of the target analytes from water samples at spiking levels of 5.0 and 50.0 ng mL(-1) were 82.2-98.8% and 83.6-104.0%, respectively. The relative standard deviations fell in the range of 4.4% to 6.3%. The method was suitable for the determination of the OPs in real water samples.

Simultaneous determination and qualitative analysis of six types of components in Naoxintong capsule by miniaturized matrix solid-phase dispersion extraction coupled with ultra high-performance liquid chromatography with photodiode array detection and quadrupole time-of-flight mass spectrometry.

PubMed

Wang, Huilin; Jiang, Yan; Ding, Mingya; Li, Jin; Hao, Jia; He, Jun; Wang, Hui; Gao, Xiu-Mei; Chang, Yan-Xu

2018-02-03

A simple and effective sample preparation process based on miniaturized matrix solid-phase dispersion was developed for simultaneous determination of phenolic acids (gallic acid, chlorogenic acid, ferulic acid, 3,5-dicaffeoylqunic acid, 1,5-dicaffeoylqunic acid, rosmarinic acid, lithospermic acid, and salvianolic acid B), flavonoids (kaempferol-3-O-rutinoside, calycosin, and formononetin), lactones (ligustilide and butyllidephthalide), monoterpenoids (paeoniflorin), phenanthraquinones (cryptotanshinone), and furans (5-hydroxymethylfurfural) in Naoxintong capsule by ultra high-performance liquid chromatography. The optimized condition was that 25 mg Naoxintong powder was blended homogeneously with 100 mg Florisil PR for 4 min. One milliliter of methanol/water (75:25, v/v) acidified by 0.05% formic acid was selected to elute all components. It was found that the recoveries of the six types of components ranged from 61.36 to 96.94%. The proposed miniaturized matrix solid-phase dispersion coupled with ultra high-performance liquid chromatography was successfully applied to simultaneous determination of the six types of components in Naoxintong capsules. The results demonstrated that the proposed miniaturized matrix solid-phase dispersion coupled with ultra high-performance liquid chromatography could be used as an environmentally friendly tool for the extraction and determination of multiple bioactive components in natural products. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A hollow coaxial cable Fabry-Pérot resonator for liquid dielectric constant measurement

NASA Astrophysics Data System (ADS)

Zhu, Chen; Zhuang, Yiyang; Chen, Yizheng; Huang, Jie

2018-04-01

We report, for the first time, a low-cost and robust homemade hollow coaxial cable Fabry-Pérot resonator (HCC-FPR) for measuring liquid dielectric constant. In the HCC design, the traditional dielectric insulating layer is replaced by air. A metal disk is welded onto the end of the HCC serving as a highly reflective reflector, and an open cavity is engineered on the HCC. After the open cavity is filled with the liquid analyte (e.g., water), the air-liquid interface acts as a highly reflective reflector due to large impedance mismatch. As a result, an HCC-FPR is formed by the two highly reflective reflectors, i.e., the air-liquid interface and the metal disk. We measured the room temperature dielectric constant for ethanol/water mixtures with different concentrations using this homemade HCC-FPR. Monitoring the evaporation of ethanol in ethanol/water mixtures was also conducted to demonstrate the ability of the sensor for continuously monitoring the change in dielectric constant. The results revealed that the HCC-FPR could be a promising evaporation rate detection platform with high performance. Due to its great advantages, such as high robustness, simple configuration, and ease of fabrication, the novel HCC-FPR based liquid dielectric constant sensor is believed to be of high interest in various fields.

A hollow coaxial cable Fabry-Pérot resonator for liquid dielectric constant measurement.

PubMed

Zhu, Chen; Zhuang, Yiyang; Chen, Yizheng; Huang, Jie

2018-04-01

We report, for the first time, a low-cost and robust homemade hollow coaxial cable Fabry-Pérot resonator (HCC-FPR) for measuring liquid dielectric constant. In the HCC design, the traditional dielectric insulating layer is replaced by air. A metal disk is welded onto the end of the HCC serving as a highly reflective reflector, and an open cavity is engineered on the HCC. After the open cavity is filled with the liquid analyte (e.g., water), the air-liquid interface acts as a highly reflective reflector due to large impedance mismatch. As a result, an HCC-FPR is formed by the two highly reflective reflectors, i.e., the air-liquid interface and the metal disk. We measured the room temperature dielectric constant for ethanol/water mixtures with different concentrations using this homemade HCC-FPR. Monitoring the evaporation of ethanol in ethanol/water mixtures was also conducted to demonstrate the ability of the sensor for continuously monitoring the change in dielectric constant. The results revealed that the HCC-FPR could be a promising evaporation rate detection platform with high performance. Due to its great advantages, such as high robustness, simple configuration, and ease of fabrication, the novel HCC-FPR based liquid dielectric constant sensor is believed to be of high interest in various fields.

Hollow Fiber Supported Ionic Liquids Liquid-Phase Micro-extraction Followed by High-Performance Liquid Chromatography for the Determination of Polycyclic Aromatic Hydrocarbons in Milk Samples.

PubMed

Wang, Meng; Cheng, Chunsheng; Liu, Chunbo; Yang, Yaling

2018-01-01

A rapid, simple, reliable and efficient hollow fiber supported ionic liquids liquid-phase micro-extraction method (IL-HF-LPME) followed by high-performance liquid chromatography was successfully applied to the determination of four kinds of polycyclic aromatic hydrocarbons (PAHs) in milk samples. In the IL-HF-LPME method, a mixture of [OMIM]PF6 and lauric acid, in a ratio of 3:1, was immobilized in the pores of a polypropylene hollow fiber used as extraction solvent. A series of essential parameters influencing the extraction efficiency were investigated and optimized. Under the optimal conditions, the extraction equilibrium is achieved within 3 min, the good linearity was >0.9990, the limits of detection varied from 0.14 to 0.71 ng/mL, the limit of quantification values were between 0.4 and 1.8 ng/mL, and the relative standard deviations were in the range of 1.24-3.27% (n = 5). The proposed method was applied to analyze four PAHs in milk samples and recoveries were between 93.6 and 102.8%. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Simultaneous determination of six synthetic phenolic antioxidants in edible oils using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with diode array detection.

PubMed

Xu, Shuangjiao; Liu, Liangliang; Wang, Yanqin; Zhou, Dayun; Kuang, Meng; Fang, Dan; Yang, Weihua; Wei, Shoujun; Xiao, Aiping; Ma, Lei

2016-08-01

A simple, rapid, organic-solvent- and sample-saving pretreatment technique, called dispersive liquid-liquid microextraction, was developed for the determination of six synthetic phenolic antioxidants from edible oils before high-performance liquid chromatography with diode array detection. The entire procedure was composed of a two-step microextraction and a centrifugal process and could be finished in about 5 min, only consuming only 25 mg of sample and 1 mL of the organic solvent for each extraction. The influences of several important parameters on the microextraction efficiency were thoroughly investigated. Recovery assays for oil samples were spiked at three concentration levels, 50, 100 and 200 mg/kg, and provided recoveries in the 86.3-102.5% range with a relative standard deviation below 3.5%. The intra-day and inter-day precisions for the analysis were less than 3.8%. The proposed method was successfully applied for the determination of synthetic phenolic antioxidants in different oil samples, and satisfactory results were obtained. Thus, the developed method represents a viable alternative for the quality control of synthetic phenolic antioxidant concentrations in edible oils. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymeric ionic liquid-based portable tip microextraction device for on-site sample preparation of water samples.

PubMed

Chen, Lei; Pei, Junxian; Huang, Xiaojia; Lu, Min

2018-06-05

On-site sample preparation is highly desired because it avoids the transportation of large-volume samples and ensures the accuracy of the analytical results. In this work, a portable prototype of tip microextraction device (TMD) was designed and developed for on-site sample pretreatment. The assembly procedure of TMD is quite simple. Firstly, polymeric ionic liquid (PIL)-based adsorbent was in-situ prepared in a pipette tip. After that, the tip was connected with a syringe which was driven by a bidirectional motor. The flow rates in adsorption and desorption steps were controlled accurately by the motor. To evaluate the practicability of the developed device, the TMD was used to on-site sample preparation of waters and combined with high-performance liquid chromatography with diode array detection to measure trace estrogens in water samples. Under the most favorable conditions, the limits of detection (LODs, S/N = 3) for the target analytes were in the range of 4.9-22 ng/L, with good coefficients of determination. Confirmatory study well evidences that the extraction performance of TMD is comparable to that of the traditional laboratory solid-phase extraction process, but the proposed TMD is more simple and convenient. At the same time, the TMD avoids complicated sampling and transferring steps of large-volume water samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Simple method for the extraction and reversed-phase high-performance liquid chromatographic analysis of carotenoid pigments from red yeasts (Basidiomycota, Fungi).

PubMed

Weber, Roland W S; Anke, Heidrun; Davoli, Paolo

2007-03-23

A simple method for the extraction of carotenoid pigments from frozen wet cells of red yeasts (Basidiomycota) and their analysis by reversed-phase HPLC using a C(18) column and a water/acetone solvent system is described. Typical red yeast carotenoids belonging to an oxidative series from the monocyclic gamma-carotene to 2-hydroxytorularhodin and from the bicyclic beta-carotene to astaxanthin were separated. Pigment identity was confirmed by LC-atmospheric pressure chemical ionisation (APCI) mass spectrometry using similar chromatographic conditions.

Simultaneous determination of carotenoids, tocopherols, retinol and cholesterol in ovine lyophilised samples of milk, meat, and liver and in unprocessed/raw samples of fat.

PubMed

Bertolín, J R; Joy, M; Rufino-Moya, P J; Lobón, S; Blanco, M

2018-08-15

An accurate, fast, economic and simple method to determine carotenoids, tocopherols, retinol and cholesterol in lyophilised samples of ovine milk, muscle and liver and raw samples of fat, which are difficult to lyophilise, is sought. Those analytes have been studied in animal tissues to trace forage feeding and unhealthy contents. The sample treatment consisted of mild overnight saponification, liquid-liquid extraction, evaporation with vacuum evaporator and redissolution. The quantification of the different analytes was performed by the use of ultra-high performance liquid chromatography with diode-array detector for carotenoids, retinol and cholesterol and fluorescence detector for tocopherols. The retention times of the analytes were short and the resolution between analytes was very high. The limits of detection and quantification were very low. This method is suitable for all the matrices and analytes and could be adapted to other animal species with minor changes. Copyright © 2018 Elsevier Ltd. All rights reserved.

Determination of dapsone in serum and saliva using reversed-phase high-performance liquid chromatography with ultraviolet or electrochemical detection.

PubMed

Moncrieff, J

1994-03-18

A simple, extractionless method for the determination of dapsone in serum and saliva is described. Reversed-phase high-performance liquid chromatography is used with UV detection at 295 nm or electrochemical detection at 0.7 V. Diazoxide in buffer is the internal standard for UV detection and practolol for electrochemical detection. Sample preparation is minimal with protein precipitation of serum samples whilst saliva samples are simply diluted with addition of an internal standard. Low-level serum and saliva samples are front-cut on-line with a 3 cm laboratory-made precolumn in the loop position on a standard Valco injection valve. Isocratic separation is achieved on a 250 mm x 4.6 mm I.D. stainless-steel Spherisorb S5 ODS-1 column. The mobile phase for high levels of dapsone is acetonitrile-elution buffer (12:88, v/v) at 2 ml/min and a column temperature of 40 degrees C for both serum and saliva separations. For the low-level assays using electrochemical detection and solid-phase clean-up, the mobile phase is acetonitrile-methanol-elution buffer (9:4:87, v/v/v). The UV and electrochemical detection limits are 25 ng/ml and 200 pg/ml, respectively, in both serum and saliva. This simple method is applicable to the routine monitoring of dapsone levels in serum from leprotic patients and electrochemical detection gives a simple, reliable method for the monitoring of trough values in subjects on anti-malarial prophylaxis.

A high-performance liquid chromatography assay to monitor the new antiepileptic drug lacosamide in patients with epilepsy.

PubMed

Greenaway, Clare; Ratnaraj, Neville; Sander, Josemir W; Patsalos, Philip N

2010-08-01

A simple high-performance liquid chromatographic micromethod is described for the quantitation of the new antiepileptic drug lacosamide in serum of patients. Serum (100 microL) was first precipitated with 10 microL 60% perchloric acid and 10 microL supernatant injected directly into the high-performance liquid chromatograph. Chromatographic separation was achieved by use of a steel cartridge column (125 x 3 mm inside diameter) packed with Hypersil BDS C-18, at 40 degrees C, and with a gradient elution system comprising methanol, formic acid and water. The eluent was monitored at 215 nm by diode array detection and the calibration curve was linear in the range of 10 to 250 micromol/L. Recovery ranged from 99% to 106%. The limit of quantification was 1 micromol/L and the intrabatch and interbatch coefficients of variation were less than 5%. No interference from commonly prescribed antiepileptic drugs (clobazam, clonazepam, carbamazepine, carbamazepine-10,11-epoxide, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, phenobarbital, phenytoin, primidone, pregabalin, valproic acid, and vigabatrin) was observed, so the method can be used to routinely monitor lacosamide in patients on polytherapy antiepileptic drug regimens.

Development of an ionic-liquid-based dispersive liquid-liquid microextraction method for the determination of antichagasic drugs in human breast milk: Optimization by central composite design.

PubMed

Padró, Juan M; Pellegrino Vidal, Rocío B; Echevarria, Romina N; Califano, Alicia N; Reta, Mario R

2015-05-01

Chagas disease constitutes a major public health problem in Latin America. Human breast milk is a biological sample of great importance for the analysis of therapeutic drugs, as unwanted exposure through breast milk could result in pharmacological effects in the nursing infant. Thus, the goal of breast milk drug analysis is to inquire to which extent a neonate may be exposed to a drug during lactation. In this work, we developed an analytical technique to quantify benznidazole and nifurtimox (the two antichagasic drugs currently available for medical treatment) in human breast milk, with a simple sample pretreatment followed by an ionic-liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography and UV detection. For this technique, the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate has been used as the "extraction solvent." A central composite design was used to find the optimum values for the significant variables affecting the extraction process: volume of ionic liquid, volume of dispersant solvent, ionic strength, and pH. At the optimum working conditions, the average recoveries were 77.5 and 89.7%, the limits of detection were 0.06 and 0.09 μg/mL and the interday reproducibilities were 6.25 and 5.77% for benznidazole and nifurtimox, respectively. The proposed methodology can be considered sensitive, simple, robust, accurate, and green. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A simple high performance liquid chromatography method for determination of rebamipide in rat urine.

PubMed

Cooper, Dustin L; Harirforoosh, Sam

2014-01-01

Rebamipide is a mucoprotective agent commonly used to prevent nonsteriodal anti-inflammatory drug-induced gastrointenstinal side effects [1]. Human plasma and urine analysis of rebamipide utilizing high performance liquid chromatography (HPLC) have been reported [2]. Recently, we reported on the plasma levels of rebamipide in presense or absence of celecoxib or diclofenac in rats [3] using a modified HPLC method of detection developed by Jeoung et al. [4]. To tailor the method towards use in urinary rebamipide extraction and analysis, the following modifications were made:•To compensate for high concentrations of rebamipide found in urine, a new rebamipide stock solution was prepared with a final concentration of 50,000 ng/mL.•Rat urine calibration standards were obtained within the range of 50-1000 ng/mL and 1000-50,000 ng/mL.•Plasma samples were replaced with urine samples.

Simple and sensitive analysis of long-chain free fatty acids in milk by fluorogenic derivatization and high-performance liquid chromatography.

PubMed

Lu, Chi-Yu; Wu, Hsin-Lung; Chen, Su-Hwei; Kou, Hwang-Shang; Wu, Shou-Mei

2002-01-02

A highly sensitive high-performance liquid chromatography (HPLC) method is described for the simultaneous determination of some important saturated and unsaturated fatty acids in milk, including lauric (dodecanoic), myristic (tetradecanoic), palmitic (hexadecanoic), stearic (octadecanoic), palmitoleic (hexadecenoic), oleic (octadecenoic), and linoleic acids (octadecadienoic acids). The fatty acids were fluorogenically derivatized with 2-(2-naphthoxy)ethyl 2-(piperidino)ethanesulfonate (NOEPES) as their naphthoxyethyl derivatives. The resulting derivatives were separated by isocratic HPLC and monitored with a fluorometric detector (lambdaex = 235 nm, lambdaem = 350 nm). The fatty acids in milk were extracted with toluene, and the extract with the fatty acids was directly derivatized with NOEPES without solvent replacement. Determination of long-chain free fatty acids in milk is feasible by a standard addition method. A small amount of milk product, 10 microL, is sufficient for the analysis.

Novel polymeric monolith materials with a β-cyclodextrin-graphene composite for the highly selective extraction of methyl jasmonate.

PubMed

Yu, Xinhong; Ling, Xu; Zou, Li; Chen, Zilin

2017-04-01

A novel polymeric monolith column with a  β-cyclodextrin-graphene composite was prepared for extraction of methyl jasmonate. A simple, sensitive, and effective polymeric monolith microextraction with high-performance liquid chromatography method has been presented for the determination. To carry out the best microextraction efficiency, several parameters such as sample flow rate, sample volume, and sample pH value were systematically optimized. In addition, the method validation showed a wide linear range of 5-2000 ng/mL, with a good linearity and low limits of detection for methyl jasmonate. The proposed method was successfully applied for the determination of methyl jasmonate in wintersweet flowers with recoveries of 90.67%. The result was confirmed by high-performance liquid chromatography with mass spectrometry. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of phenformin metabolism in rat liver microsomes by HPLC, CE and on-line HPLC-electrospray ionization mass spectrometry.

PubMed

Llambias, E B; Luo, J

1996-01-01

Methods for the analysis of phenformin and its metabolite by high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESIMS) are developed. The effects of pH, buffer concentration and proportion of organic modifier on the retention of the compounds in HPLC have been studied. The optimum condition was used for the separation and identification of phenformin and its metabolite in microsomal metabolism by HPLC-ESIMS. A simple CE method is also described for the separation of these compounds. Optimum incubation conditions and cofactor requirements for the formation of 4-hydroxyphenformin by microsomal preparations of rat liver were determined. A linear response in the formation of product was found with increasing concentrations of protein and up to 15 min incubation. High concentrations of phenformin inhibited its metabolite formation, and K(m) was 4 microM.

Determination of three estrogens and bisphenol A by functional ionic liquid dispersive liquid-phase microextraction coupled with ultra-high performance liquid chromatography and ultraviolet detection.

PubMed

Jiang, Yuehuang; Tang, Tingting; Cao, Zhen; Shi, Guoyue; Zhou, Tianshu

2015-06-01

A hydroxyl-functionalized ionic liquid, 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, was employed in an improved dispersive liquid-phase microextraction method coupled with ultra high performance liquid chromatography for the enrichment and determination of three estrogens and bisphenol A in environmental water samples. The introduced hydroxyl group acted as the H-bond acceptor that dispersed the ionic liquid effectively in the aqueous phase without dispersive solvent or external force. Fourier transform infrared spectroscopy indicated that the hydroxyl group of the cation of the ionic liquid enhanced the combination of extractant and analytes through the formation of hydrogen bonds. The improvement of the extraction efficiency compared with that with the use of alkyl ionic liquid was proved by a comparison study. The main parameters including volume of extractant, temperature, pH, and extraction time were investigated. The calibration curves were linear in the range of 5.0-1000 μg/L for estrone, estradiol, and bisphenol A, and 10.0-1000 μg/L for estriol. The detection limits were in the range of 1.7-3.4 μg/L. The extraction efficiency was evaluated by enrichment factor that were between 85 and 129. The proposed method was proved to be simple, low cost, and environmentally friendly for the determination of the four endocrine disruptors in environmental water samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A simple and rapid ultra-high-performance liquid chromatography-tandem mass spectrometry method to determine plasma biotin in hemodialysis patients.

PubMed

Yagi, Shigeaki; Nishizawa, Manabu; Ando, Itiro; Oguma, Shiro; Sato, Emiko; Imai, Yutaka; Fujiwara, Masako

2016-08-01

A simple, rapid, and selective method for determination of plasma biotin was developed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After single-step protein precipitation with methanol, biotin and stable isotope-labeled biotin as an internal standard (IS) were chromatographed on a pentafluorophenyl stationary-phase column (2.1 × 100 mm, 2.7 μm) under isocratic conditions using 10 mm ammonium formate-acetonitrile (93:7, v/v) at a flow rate of 0.6 mL/min. The total chromatographic runtime was 5 min for each injection. Detection was performed in a positive electrospray ionization mode by monitoring selected ion transitions at m/z 245.1/227.0 and 249.1/231.0 for biotin and the IS, respectively. The calibration curve was linear in the range of 0.05-2 ng/mL using 300 μL of plasma. The intra- and inter-day precisions were all <7.1%. The accuracy varied from -0.7 to 8.2%. The developed UHPLC-MS/MS method was successfully applied to determine plasma biotin concentrations in hemodialysis patients. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Highly informative multiclass profiling of lipids by ultra-high performance liquid chromatography - Low resolution (quadrupole) mass spectrometry by using electrospray ionization and atmospheric pressure chemical ionization interfaces.

PubMed

Beccaria, Marco; Inferrera, Veronica; Rigano, Francesca; Gorynski, Krzysztof; Purcaro, Giorgia; Pawliszyn, Janusz; Dugo, Paola; Mondello, Luigi

2017-08-04

A simple, fast, and versatile method, using an ultra-high performance liquid chromatography system coupled with a low resolution (single quadrupole) mass spectrometer was optimized to perform multiclass lipid profiling of human plasma. Particular attention was made to develop a method suitable for both electrospray ionization and atmospheric pressure chemical ionization interfaces (sequentially in positive- and negative-ion mode), without any modification of the chromatographic conditions (mobile phase, flow-rate, gradient, etc.). Emphasis was given to the extrapolation of the structural information based on the fragmentation pattern obtained using atmospheric pressure chemical ionization interface, under each different ionization condition, highlighting the complementary information obtained using the electrospray ionization interface, of support for related molecule ions identification. Furthermore, mass spectra of phosphatidylserine and phosphatidylinositol obtained using the atmospheric pressure chemical ionization interface are reported and discussed for the first time. Copyright © 2017 Elsevier B.V. All rights reserved.

A green ionic liquid-based vortex-forced MSPD method for the simultaneous determination of 5-HMF and iridoid glycosides from Fructus Corni by ultra-high performance liquid chromatography.

PubMed

Du, Kunze; Li, Jin; Bai, Yun; An, Mingrui; Gao, Xiu-Mei; Chang, Yan-Xu

2018-04-01

A simple and green ionic liquid-based vortex-forced matrix solid phase dispersion (IL-VFMSPD) method was presented to simultaneously extract 5-hydroxymethyl furfurol (5-HMF) and iridoid glycosides in Fructus Corni by ultra-high performance liquid chromatography. Ionic liquid was used as a green elution reagent in vortex-forced MSPD process. A few parameters such as the type of ionic liquid, the type of sorbent, ratio of sample to sorbent, the concentration and volume of ionic liquid, grinding time and vortex time, were investigated in detail and an orthogonal design experiment was introduced to confirm the best conditions in this procedure. With the final optimized method, the recoveries of the target compounds in Fructus Corni were in the range of 95.2-103% (RSD<5.0%) and the method displayed a good linearity within the range of 0.8-200 μg mL -1 for morroniside, sweroside, loganin, cornuside and 1.2-300 μg mL -1 for 5-HMF. The limits of detection ranged from 0.02 to 0.08 μg mL -1 for all compounds. The results showed that the newly established method was efficiently applied to extract and determine iridoid glycosides and 5-HMF for quality control of Fructus Corni. Copyright © 2017 Elsevier Ltd. All rights reserved.

High performance photolithographically-patterned polymer thin-film transistors gated with an ionic liquid/poly(ionic liquid) blend ion gel

NASA Astrophysics Data System (ADS)

Thiburce, Q.; Porcarelli, L.; Mecerreyes, D.; Campbell, A. J.

2017-06-01

We demonstrate the fabrication of polymer thin-film transistors gated with an ion gel electrolyte made of the blend of an ionic liquid and a polymerised ionic liquid. The ion gel exhibits a high stability and ionic conductivity, combined with facile processing by simple drop-casting from solution. In order to avoid parasitic effects such as high hysteresis, high off-currents, and slow switching, a fluorinated photoresist is employed in order to enable high-resolution orthogonal patterning of the polymer semiconductor over an area that precisely defines the transistor channel. The resulting devices exhibit excellent characteristics, with an on/off ratio of 106, low hysteresis, and a very large transconductance of 3 mS. We show that this high transconductance value is mostly the result of ions penetrating the polymer film and doping the entire volume of the semiconductor, yielding an effective capacitance per unit area of about 200 μF cm-2, one order of magnitude higher than the double layer capacitance of the ion gel. This results in channel currents larger than 1 mA at an applied gate bias of only -1 V. We also investigate the dynamic performance of the devices and obtain a switching time of 20 ms, which is mostly limited by the overlap capacitance between the ion gel and the source and drain contacts.

[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.

C18-coated stir bar sorptive extraction combined with high performance liquid chromatography-electrospray tandem mass spectrometry for the analysis of sulfonamides in milk and milk powder.

PubMed

Yu, Chunhe; Hu, Bin

2012-02-15

A simple, rapid, sensitive, inexpensive and less sample consuming method of C(18)-stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS) was proposed for the determination of six sulfonamides in milk and milk powder samples. C(18) silica particles coated stir bar was prepared by adhesion method, and two kinds of adhesive glue, polydimethylsiloxane (PDMS) sol and epoxy glue were tried. It was found that the C(18)-coated stir bar prepared by PDMS sol as adhesive glue is more robust than that prepared by epoxy glue when liquid desorption was employed, in terms of both lifetime and organic solvent tolerance. The preparation of C(18) stir bar was simple with good mechanic strength and the stir bar could be reused for more than 20 times. Granular coating has relatively high specific surface area and is propitious to sorptive extraction based process. Compared to conventional PDMS SBSE coating, C(18) coating shows good affinity to the target polar/weak polar sulfonamides. To achieve optimum SBSE extraction performance, several parameters including extraction and desorption time, ionic strength, sample pH and stirring speed were investigated. The detection limits of the proposed method for six sulfonamides were in the range of 0.9-10.5 μg/L for milk and 2.7-31.5 μg/kg for milk powder. Good linearities were obtained for sulfonamides with the correlation coefficients (R) above 0.9922. Finally, the proposed method was successfully applied to the determination of sulfonamides in milk and milk powder samples and satisfied recoveries of spiked target compounds in real samples were obtained. Copyright © 2012 Elsevier B.V. All rights reserved.

Detection of Organophosphorus Pesticides in Wheat by Ionic Liquid-Based Dispersive Liquid-Liquid Microextraction Combined with HPLC

PubMed Central

Quan, Ji; Hu, Zeshu

2018-01-01

Food safety issues closely related to human health have always received widespread attention from the world society. As a basic food source, wheat is the fundamental support of human survival; therefore, the detection of pesticide residues in wheat is very necessary. In this work, the ultrasonic-assisted ionic liquid-dispersive liquid-liquid microextraction (DLLME) method was firstly proposed, and the extraction and analysis of three organophosphorus pesticides were carried out by combining high-performance liquid chromatography (HPLC). The extraction efficiencies of three ionic liquids with bis(trifluoromethylsulfonyl)imide (Tf2N) anion were compared by extracting organophosphorus in wheat samples. It was found that the use of 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([OMIM][Tf2N]) had both high enrichment efficiency and appropriate extraction recovery. Finally, the method was used for the determination of three wheat samples, and the recoveries of them were 74.8–112.5%, 71.8–104.5%, and 83.8–115.5%, respectively. The results show that the method proposed is simple, fast, and efficient, which can be applied to the extraction of organic matters in wheat samples. PMID:29854562

Simultaneous determination of four trace estrogens in feces, leachate, tap and groundwater using solid-liquid extraction/auto solid-phase extraction and high-performance liquid chromatography with fluorescence detection.

PubMed

Liu, Na; Shi, Yue-e; Li, Mengyan; Zhang, Ting-di; Gao, Song

2015-10-01

A simple and selective high-performance liquid chromatography method coupled with fluorescence detection was developed for the simultaneous measurement of trace levels of four estrogens (estrone, estradiol, estriol and 17α-ethynyl estradiol) in environmental matrices. For feces samples, solid-liquid extraction was applied with a 1:1 v/v mixture of acetonitrile and ethyl acetate as the extraction solvent. For liquid samples (e.g., leachate and groundwater), hydrophobic/lipophilic balanced automated solid-phase extraction disks were selected due to their high recoveries compared to conventional C18 disks. Chromatographic separations were performed on a reversed-phase C18 column gradient-eluted with a 45:55 v/v mixture of acetonitrile and water. The detection limits were down to 1.1 × 10(-2) (estrone), 4.11 × 10(-4) (estradiol), 5.2 × 10(-3) (estriol) and 7.18 × 10(-3) μg/L (17α-ethynyl estradiol) at excitation/emission wavelengths of 288/310 nm, with recoveries in the range of 96.9 ± 3.2-105.4 ± 3.2% (n = 3). The method was successfully applied to determine estrogens in feces and water samples collected at livestock farms and a major river in Northeast China. We observed relatively high abundance and widespread distribution of all four estrogens in our sample collections, implying the urgency for a comprehensive and intricate investigation of estrogenic fate and contamination in our researched area. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Isolation and purification of seven catechin compounds from fresh tea leaves by semi-preparative liquid chromatography].

PubMed

Gong, Zhihong; Chen, Si; Gao, Jiangtao; Li, Meihong; Wang, Xiaxia; Lin, Jun; Yu, Xiaomin

2017-11-08

An effective and simple method was established to simultaneously purify seven tea catechins (gallocatechin (GC), epigallocatechin (EGC), catechin (C), epigallocatechin-3- O -gallate (EGCG), epicatechin (EC), epigallocatechin-3- O -(3- O -methyl)-gallate (EGCG3"Me) and epicatechin-3- O -gallate (ECG)) from fresh tea leaves by semi-preparative high performance liquid chromatography (HPLC). Fresh leaves of Tieguanyin tea were successively extracted with methanol and chloroform. Then crude catechins were precipitated from the aqueous fraction of chloroform extraction by adding lead subacetate. Crude catechins were used for the isolation of the seven target catechin compounds by semi-preparative HPLC. Methanol-water and acetonitrile-water were sequentially used as mobile phases. After two rounds of semi-preparative HPLC, all target compounds were achieved with high purities (>90%). The proposed method was tested on two additional tea cultivars and showed similar results. This method demonstrated a simple and efficient strategy based on solvent extraction, ion precipitation and semi-preparative HPLC for the preparation of multiple catechins from tea leaves.

Development and Validation of a Fast Procedure to Analyze Amoxicillin in River Waters by Direct-Injection LC-MS/MS

ERIC Educational Resources Information Center

Homem, Vera; Alves, Arminda; Santos, Lu´cia

2014-01-01

A laboratory application with a strong component in analytical chemistry was designed for undergraduate students, in order to introduce a current problem in the environmental science field, the water contamination by antibiotics. Therefore, a simple and rapid method based on direct injection and high performance liquid chromatography-tandem mass…

Gradient Scouting in Reversed-Phase HPLC Revisited

ERIC Educational Resources Information Center

Alcazar, A.; Jurado, J. M.; Gonzalez, A. G.

2011-01-01

Gradient scouting is the best way to decide the most suitable elution mode in reversed-phase high-performance liquid chromatography (RP-HPLC). A simple rule for this decision involves the evaluation of the ratio [delta]t/t[subscript G] (where [delta]t is the difference in the retention time between the last and the first peak and t[subscript G] is…

[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.

Simple high-performance liquid chromatographic method to monitor vigabatrin, and preliminary review of concentrations determined in epileptic patients.

PubMed

George, S; Gill, L; Braithwaite, R A

2000-05-01

A simple and rapid high-performance liquid chromatographic method has been developed for the determination of vigabatrin concentrations in plasma or serum. The assay uses only 100 microL of specimen and has been found to be linear over a concentration range of 1 to 50 mg/L. The limit of detection has been determined as 1 mg/L, and the between-batch coefficient of variation for the two internal quality controls routinely analysed (n = 33) has been found to be less than 5%. There was no evidence of interferences in the assay from other commonly prescribed anti-epileptic drugs. This method has been applied to routine clinical specimens to determine the concentration of vigabatrin in 47 patient specimens over a 12-month period. It was found that only 63% of the male group and 53% of the female group were within the proposed target concentration of 5 to 35 mg/L. In addition, it was found that 26% of the male group and 36% of the female group were found to have concentrations below 5 mg/L, which may indicate lack of compliance and/or lack of therapeutic efficacy of treatment.

[Determination of paraquat and diquat in drinking water and environmental water by high performance liquid chromatography coupled with on-line clean-up and solid phase extraction].

PubMed

Chen, Jing; Liu, Zhaojin; An, Baochao; Lu, Yan; Xu, Qun

2012-10-01

An on-line solid phase extraction (SPE) system was used to eliminate the interferences sufficiently and fulfill the simple and sensitive determination of diquat and paraquat in tap and pond water. This on-line SPE system used two SPE cartridges. One was an Acclaim Mixed-Mode WAX-1 cartridge for the elimination of anionic interferences; the other one was an Acclaim Mixed-Mode WCX-1 cartridge for the enrichment of diquat and paraquat and the elimination of co-enriched cationic interferences. The baseline separation of diquat and paraquat was achieved on an Acclaim Trinity P1 column. A dual-gradient high performance liquid chromatographic (HPLC) system provided an efficient platform to fulfill the on-line SPE and separation, and the system operated under automatic control of chromatography data system software. The complete analysis only required 16 min, and the detection limits of the method were 0.12 microg/L for diquat and 0.10 microg/L for paraquat. The method is simple, rapid and sensitive, and can be applied to the determination of diquat and paraquat in drinking water and environmental water.

Development of a high-throughput method for the determination of ethosuximide in human plasma by liquid chromatography mass spectrometry.

PubMed

Bhatt, Mitesh; Shah, Sanjay; Shivprakash

2010-06-01

A simple, rapid, sensitive and specific ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the quantification of ethosuximide in human plasma is described. Analyte was chromatographed on a Hypersil Gold C18 column (100 mm x 2.1 mm, i.d., 1.9 microm) with isocratic elution at a flow rate of 0.250 mL/min and pravastatin was used as the internal standard. The assay involves a simple solid-phase extraction procedure of 0.25 mL human plasma and the analysis was performed on a triple-quadrupole tandem mass spectrometer by MRM mode via electrospray ionization (ESI). The method was linear in the concentration range of 0.25-60.0 microg/mL. The lower limit of quantification (LLOQ) was 0.25 microg/mL. The within- and between-day precision and accuracy of the quality control samples were within 10.0%. The recovery was 95.1% and 94.4% for ethosuximide and pravastatin, respectively. The analysis time for each sample was 1.8 min. The method was highly reproducible and gave peaks with excellent chromatography properties. Copyright 2010 Elsevier B.V. All rights reserved.

Simple Quantification of Pentosidine in Human Urine and Plasma by High-Performance Liquid Chromatography

PubMed Central

Lee, Ji Sang; Chung, Yoon-Sok; Chang, Sun Young

2017-01-01

Pentosidine is an advanced glycation end-product (AGE) and fluorescent cross-link compound. A simple high-performance liquid chromatographic (HPLC) method was developed for the detection and quantification of pentosidine in human urine and plasma. The mobile phase used a gradient system to improve separation of pentosidine from endogenous peaks, and chromatograms were monitored by fluorescent detector set at excitation and emission wavelengths of 328 and 378 nm, respectively. The retention time for pentosidine was 24.3 min and the lower limits of quantification (LLOQ) in human urine and plasma were 1 nM. The intraday assay precisions (coefficients of variation) were generally low and found to be in the range of 5.19–7.49% and 4.96–8.78% for human urine and plasma, respectively. The corresponding values of the interday assay precisions were 9.45% and 4.27%. Accuracies (relative errors) ranged from 87.9% to 115%. Pentosidine was stable in a range of pH solutions, human urine, and plasma. In summary, this HPLC method can be applied in future preclinical and clinical evaluation of pentosidine in the diabetic patients. PMID:29181026

Simultaneous separation and determination of eleven nucleosides and bases in beer, herring sperm DNA and RNA soft capsule by high-performance liquid chromatography.

PubMed

Hou, Shengjie; Ding, Mingyu

2010-01-01

A simple and rapid high-performance liquid chromatography method was developed for the determination of eleven nucleosides and bases in beer, herring sperm DNA and RNA soft capsules. The separation was carried out on an Agilent extend-C(18) column with a simple gradient elution of acetonitrile and water as the mobile phase. Good linear relationships between the peak areas and the concentrations of the analytes were obtained. The detection limits for eleven analytes were in the range of 0.007-0.037 mg/L by UV detection at 260 nm. The relative standard deviations (RSDs) of the retention times were in the range of 0.78-1.85% for intra-day and 0.87-1.94% for inter-day, respectively. The RSDs of the peak areas were in the range of 2.71-3.22% for intra-day and 3.03-3.39% for inter-day, respectively. This method has been successfully applied to simultaneous determination of eleven nucleosides and bases in beer, herring sperm DNA and RNA soft capsules with the recoveries in the range of 93.7-108.3%.

The Development and Validation of Novel, Simple High-Performance Liquid Chromatographic Method with Refractive Index Detector for Quantification of Memantine Hydrochloride in Dissolution Samples.

PubMed

Sawant, Tukaram B; Wakchaure, Vikas S; Rakibe, Udyakumar K; Musmade, Prashant B; Chaudhari, Bhata R; Mane, Dhananjay V

2017-07-01

The present study was aimed to develop an analytical method for quantification of memantine (MEM) hydrochloride in dissolution samples using high-performance liquid chromatography with refractive index (RI) detector. The chromatographic separation was achieved on C18 (250 × 4.5 mm, 5 μm) column using isocratic mobile phase comprises of buffer (pH 5.2):methanol (40:60 v/v) pumped at a flow rate of 1.0 mL/min. The column effluents were monitored using RI detector. The retention time of MEM was found to be ~6.5 ± 0.3 min. The developed chromatographic method was validated and found to be linear over the concentration range of 5.0-45.0 μg/mL for MEM. Mean recovery of MEM was found to be 99.2 ± 0.5% (w/w). The method was found to be simple, fast, precise and accurate, which can be utilized for the quantification of MEM in dissolution samples. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

High-performance liquid chromatography coupled with post-column dual-bioactivity assay for simultaneous screening of xanthine oxidase inhibitors and free radical scavengers from complex mixture.

PubMed

Li, D Q; Zhao, J; Li, S P

2014-06-06

Xanthine oxidase (XO) can catalyze hypoxanthine and xanthine to generate uric acid and reactive oxygen species (ROS), including superoxide anion radical (O₂(•-)) and hydrogen peroxide. XO inhibitors and free radical scavengers are beneficial to the treatment of gout and many related diseases. In the present study, an on-line high-performance liquid chromatography (HPLC) coupled with post-column dual-bioactivity assay was established and successfully applied to simultaneously screening of XO inhibitors and free radical scavengers from a complex mixture, Oroxylum indicum extract. The integrated system of HPLC separation, bioactivity screening and mass spectrometry identification was proved to be simple and effective for rapid and sensitive screening of individual bioactive compounds in complex mixtures. Copyright © 2014 Elsevier B.V. All rights reserved.

Application of solvent floatation to separation and determination of triazine herbicides in honey by high-performance liquid chromatography.

PubMed

Wang, Kun; Jiang, Jia; Lv, Xinping; Zang, Shuang; Tian, Sizhu; Zhang, Hanqi; Yu, Aimin; Zhang, Ziwei; Yu, Yong

2018-03-01

Based on the foaming property of the honey, a rapid, simple, and effective method solvent floatation (SF) was developed and firstly applied to the extraction and separation of triazine herbicides in honey. The analytes were determined by high-performance liquid chromatography. Some parameters affecting the extraction efficiencies, such as the type and volume of extraction solvent, type of salt, amount of (NH 4 ) 2 SO 4 , pH value of sample solution, gas flow rate, and floatation time, were investigated and optimized. The limits of detection for analytes are in the range of 0.16-0.56 μg kg -1 . The recoveries and relative standard deviations for determining triazines in five real honey samples are in the range of 78.2-112.9 and 0.2-9.2%, respectively.

Paired-ion chromatography and high performance liquid chromatography of labetalol in feeds.

PubMed

Townley, E R; Ross, B

1980-11-01

A high performance liquid chromatographic (HPLC) method using reverse phase paired-ion chromatography and ultraviolet detection at 280 nm has been developed to determine labetalol, an alpha and beta adrenoceptor blocking agent, in Purina No. 5001 rodent chow. The method is simple and rapid, and demonstrates a separation technique applicable to other acidic and basic drugs. It requires only extraction of the drug with methanol--water--acetic acid (66 + 33 + 1) and separation of insoluble material by filtration before HPLC. Labetalol, is chromatographically separated from soluble feed components by means of a microBondapak C18 column and methanol--water--acetic acid (66 + 33 + 1) mobile phase, 0.005M with respect to sodium dioctylsulfosuccinate paired-ion reagent. Average recovery is 98.7% with a relative standard deviation of +/- 2.3% for the equipment described.

High performance liquid chromatography method for the determination of cinnamyl alcohol dehydrogenase activity in soybean roots.

PubMed

dos Santos, W D; Ferrarese, Maria de Lourdes Lucio; Ferrarese-Filho, O

2006-01-01

This study proposes a simple, quick and reliable method for determining the cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) activity in soybean (Glycine max L. Merr.) roots using reversed-phase high performance liquid chromatography (RP-HPLC). The method includes a single extraction of the tissue and conduction of the enzymatic reaction at 30 degrees C with cinnamaldehydes (coniferyl or sinapyl), substrates of CAD. Disappearance of the substrates in the reaction mixture is monitored at 340 nm (for coniferaldehyde) or 345 nm (for sinapaldehyde) by isocratic elution with methanol/acetic acid through a GLC-ODS (M) column. This HPLC technique furnishes a rapid and reliable measure of cinnamaldehyde substrates, and may be used as an alternative tool to analyze CAD activity in enzyme preparation without previous purification.

Identification and characterization of potential impurities of donepezil.

PubMed

Krishna Reddy, K V S R; Moses Babu, J; Kumar, P Anil; Chandrashekar, E R R; Mathad, Vijayavitthal T; Eswaraiah, S; Reddy, M Satyanarayana; Vyas, K

2004-09-03

Five unknown impurities ranging from 0.05 to 0.2% in donepezil were detected by a simple isocratic reversed-phase high performance liquid chromatography (HPLC). These impurities were isolated from crude sample of donepezil using isocratic reversed-phase preparative high performance liquid chromatography. Based on the spectral data (IR, NMR and MS), the structures of these impurities were characterised as 5,6-dimethoxy-2-(4-pyridylmethyl)-1-indanone (impurity I), 4-(5,6-dimethoxy-2,3-dihydro-1H-2-indenylmethyl) piperidine (impurity II), 2-(1-benzyl-4-piperdylmethyl)-5,6-dimethoxy-1-indanol (impurity III) 1-benzyl-4(5,6-dimethoxy-2,3-dihydro-1H-2-indenylmethyl) piperidine (impurity IV) and 1,1-dibenzyl-4(5,6-dimethoxy-1-oxo-2,3-dihydro-2H-2-indenylmethyl)hexahydropyridinium bromide (impurity V). The synthesis of these impurities and their formation was discussed.

Analysis of glyoxal and related substances by means of high-performance liquid chromatography with refractive index detection.

PubMed

Zhang, Zhiyong; Zhao, Dishun; Xu, Baoyun

2013-01-01

A simple and rapid method is described for the analysis of glyoxal and related substances by high-performance liquid chromatography with a refractive index detector. The following chromatographic conditions were adopted: Aminex HPX-87H column, mobile phase consisting of 0.01N H2SO4, flow rate of 0.8 mL/min and temperature of 65°C. The application of the analytical technique developed in this study demonstrated that the aqueous reaction mixture produced by the oxidation of acetaldehyde with HNO3 was composed of glyoxal, acetaldehyde, acetic acid, formic acid, glyoxylic acid, oxalic acid, butanedione and glycolic acid. The method was validated by evaluating analytical parameters such as linearity, limits of detection and quantification, precision, recovery and robustness. The proposed methodology was successfully applied to the production of glyoxal.

Ultra-high performance liquid chromatography with fluorescence detection following salting-out assisted liquid-liquid extraction for the analysis of benzimidazole residues in farm fish samples.

PubMed

Tejada-Casado, Carmen; Lara, Francisco J; García-Campaña, Ana M; Del Olmo-Iruela, Monsalud

2018-03-30

Ultra-high performance liquid chromatography (UHPLC) coupled with fluorescence detection (FL) has been proposed for the first time to determine thirteen benzimidazoles (BZs) in farmed fish samples. In order to optimize the chromatographic separation, parameters such as mobile phase composition and flow rate were carefully studied, establishing a gradient mode with a mobile phase consisted of water (solvent A) and acetonitrile (solvent B) at a flow rate of 0.4 mL/min. The separation was performed on a Zorbax Eclipse Plus RRHD C 18 column (50 × 2.1 mm, 1.8 μm), involving a total analysis time lower than 12 min. Salting-out assisted liquid-liquid extraction (SALLE) was applied as sample treatment to different types of farmed fish (trout, sea bream and sea bass). To obtain satisfactory extraction efficiencies for the studied analytes, several parameters affecting the SALLE procedure were optimized including the amount of sample, type and volume of the extraction solvent, and the nature and amount of the salt used. Characterization of the method in terms of performance characteristics was carried out, obtaining satisfactory results for the linearity (R 2  ≥ 0.997), repeatability (RSD ≤ 6.1%), reproducibility (RSD ≤ 10.8%) and recoveries (R ≥ 79%; RSD ≤ 7.8%). Detection limits between 0.04-29.9 μg kg -1 were obtained, demonstrating the applicability of this fast, simple and environmentally friendly method. Copyright © 2018 Elsevier B.V. All rights reserved.

High performance liquid chromatography coupled with resonance Rayleigh scattering for the detection of three fluoroquinolones and mechanism study

NASA Astrophysics Data System (ADS)

Zhou, Mingqiong; Peng, Jingdong; He, Rongxing; He, Yuting; Zhang, Jing; Li, Aiping

2015-02-01

A reliable and versatile high performance liquid chromatography coupled with resonance Rayleigh scattering method was established for the determination of three fluoroquinolones, including levofloxacin, norfloxacin and enrofloxacin in water sample and human urine sample. In pH 4.4-4.6 Britton-Robinson buffer medium, the fluoroquinolones separated by high performance liquid chromatography could react with erythrosine to form 1:1 ion-association complexes, which could make contributions to the great enhancement of RRS. The resonance Rayleigh scattering signal was recorded at λex = λem = 330 nm. The resonance Rayleigh scattering spectral characteristics of the drugs and the experimental conditions such as pH, detection wavelength, erythrosine concentration, flow rate, the length of reaction tube were studied. Quantum chemistry calculation, Fourier transform infrared spectroscopy and absorption spectroscopy were used to discuss the reaction mechanism. The recoveries of samples added standard ranged from 97.53% to 102.00%, and the relative standard deviation was below 4.64%. The limit of detection (S/N = 3) of 0.05-0.12 μg mL-1 was reached, and the linear regression coefficients were all above 0.999. The proposed method was proved as a simple, low cost and high sensitivity method.

Magnetic molecularly imprinted polymers for the determination of β-agonist residues in milk by ultra high performance liquid chromatography with tandem mass spectrometry.

PubMed

Liu, Hongcheng; Lin, Xin; Lin, Tao; Zhang, Yulong; Luo, Yinglan; Li, Qiwan

2016-09-01

A simple, accurate, and highly sensitive analytical method was developed in this study for the determination of nine β-agonists in milk. In this method, a new magnetic adsorbent of molecularly imprinted polymers/magnetic nanoparticles prepared by simple physical blending was adopted, which enabled magnetic solid-phase extraction. Thus, the resultant material can be separated from the solvent rapidly and conveniently by a magnet. Two kinds of molecularly imprinted polymer/magnetic nanoparticles materials were fabricated, and the characteristics of materials such as the ratio, pH, amount, desorption, and regeneration were investigated. The analytes were quantified by ultra high performance liquid chromatography coupled to an electrospray ionization tandem mass spectrometer operating in multiple reaction monitoring modes. The detection limit of the method was 0.003-0.3 μg/L, and the detection capability was 0.01-0.3 μg/L. The recoveries of these compounds were 65.7-114% at three spiked levels. Reproducibility represented by relative standard deviation was 11.2% or less. The method was successfully applied to the screening of real samples obtained from local markets and confirmation of the suspected target analytes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel method for the rapid detection of benzo(a)pyrene in liquid milk by dimethyl sulfoxide selectively enhanced synchronous fluorescence spectrometry.

PubMed

Lin, Li-Rong; Luo, He-Dong; Li, Xiu-Ying; Li, Na; Zhou, Na; Jia, Yu-Zhu; Liu, Yi-Hong; Li, Yao-Qun

2014-01-01

Based on the high solubility efficiency and strong fluorescence response of benzo(a)pyrene (BaP) in dimethyl sulfoxide in combination with the high-performance derivative constant-energy synchronous fluorescence spectroscopic (DCESFS) technique, a simple, sensitive and economic method was developed for the determination of BaP in liquid milk. This method comprises ultrasound-assisted solvent extraction, solvent replacement and DCESFS detection. No saponification or other tedious clean-up procedures were needed. The recoveries of BaP in different milk samples were greater than 82%. Detection limits in full- and low-fat milk were 0.03 and 0.04 μg kg(-1), respectively.

Determination of steroid sex hormones in wastewater by stir bar sorptive extraction based on poly(vinylpyridine-ethylene dimethacrylate) monolithic material and liquid chromatographic analysis.

PubMed

Huang, Xiaojia; Lin, Jianbin; Yuan, Dongxing; Hu, Rongzong

2009-04-17

In this study, a simple and rapid method was developed for the determination of seven steroid hormones in wastewater. Sample preparation and analysis were performed by stir bar sorptive extraction (SBSE) based on poly(vinylpyridine-ethylene dimethacrylate) monolithic material (SBSEM) combined with high-performance liquid chromatography with diode array detection. To achieve the optimum extraction performance, several main parameters, including extraction and desorption time, pH value and contents of inorganic salt in the sample matrix, were investigated. Under the optimized experimental conditions, the method showed good linearity and repeatability, as well as advantages such as sensitivity, simplicity, low cost and high feasibility. The extraction performance of SBSEM to the target compounds also compared with commercial SBSE which used polydimethylsiloxane as coating. Finally, the proposed method was successfully applied to the determination of the target compounds in wastewater samples. The recoveries of spiked target compounds in real samples ranged from 48.2% to 110%.

Determination of three steroidal saponins from Ophiopogon japonicus (Liliaceae) via high-performance liquid chromatography with mass spectrometry.

PubMed

Wang, Yongyi; Xu, Jinzhong; Qu, Haibin

2013-01-01

A simple and accurate analytical method was developed for simultaneous quantification of three steroidal saponins in the roots of Ophiopogon japonicus via high-performance liquid chromatography (HPLC) with mass spectrometry (MS) in this study. Separation was performed on a Tigerkin C(18) column and detection was performed by mass spectrometry. A mobile phase consisted of 0.02% formic acid in water (v/v) and 0.02% formic acid in acetonitrile (v/v) was used with a flow rate of 0.5 mL min(-1). The quantitative HPLC-MS method was validated for linearity, precision, repeatability, stability, recovery, limits of detection and quantification. This developed method provides good linearity (r >0.9993), intra- and inter-day precisions (RSD <4.18%), repeatability (RSD <5.05%), stability (RSD <2.08%) and recovery (93.82-102.84%) for three steroidal saponins. It could be considered as a suitable quality control method for O. japonicus.

Analysis of gas turbine engines using water and oxygen injection to achieve high Mach numbers and high thrust

NASA Technical Reports Server (NTRS)

Henneberry, Hugh M.; Snyder, Christopher A.

1993-01-01

An analysis of gas turbine engines using water and oxygen injection to enhance performance by increasing Mach number capability and by increasing thrust is described. The liquids are injected, either separately or together, into the subsonic diffuser ahead of the engine compressor. A turbojet engine and a mixed-flow turbofan engine (MFTF) are examined, and in pursuit of maximum thrust, both engines are fitted with afterburners. The results indicate that water injection alone can extend the performance envelope of both engine types by one and one-half Mach numbers at which point water-air ratios reach 17 or 18 percent and liquid specific impulse is reduced to some 390 to 470 seconds, a level about equal to the impulse of a high energy rocket engine. The envelope can be further extended, but only with increasing sacrifices in liquid specific impulse. Oxygen-airflow ratios as high as 15 percent were investigated for increasing thrust. Using 15 percent oxygen in combination with water injection at high supersonic Mach numbers resulted in thrust augmentation as high as 76 percent without any significant decrease in liquid specific impulse. The stoichiometric afterburner exit temperature increased with increasing oxygen flow, reaching 4822 deg R in the turbojet engine at a Mach number of 3.5. At the transonic Mach number of 0.95 where no water injection is needed, an oxygen-air ratio of 15 percent increased thrust by some 55 percent in both engines, along with a decrease in liquid specific impulse of 62 percent. Afterburner temperature was approximately 4700 deg R at this high thrust condition. Water and/or oxygen injection are simple and straightforward strategies to improve engine performance and they will add little to engine weight. However, if large Mach number and thrust increases are required, liquid flows become significant, so that operation at these conditions will necessarily be of short duration.

Ionic-liquid-based dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the forensic determination of methamphetamine in human urine.

PubMed

Wang, Ruifeng; Qi, Xiujuan; Zhao, Lei; Liu, Shimin; Gao, Shuang; Ma, Xiangyuan; Deng, Youquan

2016-07-01

Determination of methamphetamine in forensic laboratories is a major issue due to its health and social harm. In this work, a simple, sensitive, and environmentally friendly method based on ionic liquid dispersive liquid-liquid microextraction combined with high-performance liquid chromatography was established for the analysis of methamphetamine in human urine. 1-Octyl-3-methylimidazolium hexafluorophosphate with the help of disperser solvent methanol was selected as the microextraction solvent in this process. Various parameters affecting the extraction efficiency of methamphetamine were investigated systemically, including extraction solvent and its volume, disperser solvent and its volume, sample pH, extraction temperature, and centrifugal time. Under the optimized conditions, a good linearity was obtained in the concentration range of 10-1000 ng/mL with determination coefficient >0.99. The limit of detection calculated at a signal-to-noise ratio of 3 was 1.7 ng/mL and the relative standard deviations for six replicate experiments at three different concentration levels of 100, 500, and 1000 ng/mL were 6.4, 4.5, and 4.7%, respectively. Meanwhile, up to 220-fold enrichment factor of methamphetamine and acceptable extraction recovery (>80.0%) could be achieved. Furthermore, this method has been successfully employed for the sensitive detection of a urine sample from a suspected drug abuser. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A 20-liter test stand with gas purification for liquid argon research

DOE PAGES

Li, Y.; Thorn, C.; Tang, W.; ...

2016-06-06

Here, we describe the design of a 20-liter test stand constructed to study fundamental properties of liquid argon (LAr). Moreover, this system utilizes a simple, cost-effective gas argon (GAr) purification to achieve high purity, which is necessary to study electron transport properties in LAr. An electron drift stack with up to 25 cm length is constructed to study electron drift, diffusion, and attachment at various electric fields. Finally, a gold photocathode and a pulsed laser are used as a bright electron source. The operational performance of this system is reported.

A 20-liter test stand with gas purification for liquid argon research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Y.; Thorn, C.; Tang, W.

Here, we describe the design of a 20-liter test stand constructed to study fundamental properties of liquid argon (LAr). Moreover, this system utilizes a simple, cost-effective gas argon (GAr) purification to achieve high purity, which is necessary to study electron transport properties in LAr. An electron drift stack with up to 25 cm length is constructed to study electron drift, diffusion, and attachment at various electric fields. Finally, a gold photocathode and a pulsed laser are used as a bright electron source. The operational performance of this system is reported.

Development and validation of a RP-HPLC method for the quantitation of tofacitinib in rat plasma and its application to a pharmacokinetic study.

PubMed

S, Vijay Kumar; Dhiman, Vinay; Giri, Kalpesh Kumar; Sharma, Kuldeep; Zainuddin, Mohd; Mullangi, Ramesh

2015-09-01

A novel, simple, specific, sensitive and reproducible high-performance liquid chromatography (HPLC) assay method has been developed and validated for the estimation of tofacitinib in rat plasma. The bioanalytical procedure involves extraction of tofacitinib and itraconazole (internal standard, IS) from rat plasma with a simple liquid-liquid extraction process. The chromatographic analysis was performed on a Waters Alliance system using a gradient mobile phase conditions at a flow rate of 1.0 mL/min and C18 column maintained at 40 ± 1 °C. The eluate was monitored using an UV detector set at 287 nm. Tofacitinib and IS eluted at 6.5 and 8.3 min, respectively and the total run time was 10 min. Method validation was performed as per US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over a concentration range of 182-5035 ng/mL (r(2) = 0.995). The intra- and inter-day precisions were in the range of 1.41-11.2 and 3.66-8.81%, respectively, in rat plasma. The validated HPLC method was successfully applied to a pharmacokinetic study in rats. Copyright © 2015 John Wiley & Sons, Ltd.

Microwave-assisted ionic liquid homogeneous liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of anthraquinones in Rheum palmatum L.

PubMed

Wang, Zhibing; Hu, Jianxue; Du, Hongxia; He, Shuang; Li, Qing; Zhang, Hanqi

2016-06-05

The microwave-assisted ionic liquid homogeneous liquid-liquid microextraction (MA-IL-HLLME) coupled with high performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of anthraquinones, including aloe-emodin, emodin, chrysophanol and physcion in root of Rheum palmatum L. Several experimental parameters influencing the extraction efficiency, including amount of sample, type and volume of ionic liquid, volume and pH value of extraction medium, microwave power and extraction time, concentration of NH4PF6 as well as centrifugal condition were optimized. When 140μL of ionic liquid ([C8MIM][BF4]) was used as an extraction solvent, target analytes can be extracted from sample matrix in one minute with the help of microwave irradiation. The MA-IL-HLLME is simple and quick. The calibration curves exhibited good linear relationship (r>0.9984). The limits of detection and quantification were in the range of 0.015-0.026 and 0.051-0.088μgmL(-1), respectively. The spiked recovery for each analyte was in the range of 81.13-93.07% with relative standard deviations lower than 6.89%. The present method is free of volatile organic solvents, and represents lower expenditures of sample, extraction time and solvent, compared with ultrasonic and heat reflux extraction. The results indicated that the present method can be successfully applied to the determination of anthraquinones in medicinal plant. Copyright © 2016 Elsevier B.V. All rights reserved.

Extended temperature range ACPS thruster investigation

NASA Technical Reports Server (NTRS)

Blubaugh, A. L.; Schoenman, L.

1974-01-01

The successful hot fire demonstration of a pulsing liquid hydrogen/liquid oxygen and gaseous hydrogen/liquid oxygen attitude control propulsion system thruster is described. The test was the result of research to develop a simple, lightweight, and high performance reaction control system without the traditional requirements for extensive periods of engine thermal conditioning, or the use of complex equipment to convert both liquid propellants to gas prior to delivery to the engine. Significant departures from conventional injector design practice were employed to achieve an operable design. The work discussed includes thermal and injector manifold priming analyses, subscale injector chilldown tests, and 168 full scale and 550 N (1250 lbF) rocket engine tests. Ignition experiments, at propellant temperatures ranging from cryogenic to ambient, led to the generation of a universal spark ignition system which can reliably ignite an engine when supplied with liquid, two phase, or gaseous propellants. Electrical power requirements for spark igniter are very low.

[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.

Evaluation of on-board hydrogen storage methods f or high-speed aircraft

NASA Technical Reports Server (NTRS)

Akyurtlu, Ates; Akyurtlu, Jale F.

1991-01-01

Hydrogen is the fuel of choice for hypersonic vehicles. Its main disadvantage is its low liquid and solid density. This increases the vehicle volume and hence the drag losses during atmospheric flight. In addition, the dry mass of the vehicle is larger due to larger vehicle structure and fuel tankage. Therefore it is very desirable to find a fuel system with smaller fuel storage requirements without deteriorating the vehicle performance substantially. To evaluate various candidate fuel systems, they were first screened thermodynamically with respect to their energy content and cooling capacities. To evaluate the vehicle performance with different fuel systems, a simple computer model is developed to compute the vehicle parameters such as the vehicle volume, dry mass, effective specific impulse, and payload capacity. The results indicate that if the payload capacity (or the gross lift-off mass) is the most important criterion, only slush hydrogen and liquid hydrogen - liquid methane gel shows better performance than the liquid hydrogen vehicle. If all the advantages of a smaller vehicle are considered and a more accurate mass analysis can be performed, other systems using endothermic fuels such as cyclohexane, and some boranes may prove to be worthy of further consideration.

Liquid-liquid critical point in a simple analytical model of water.

PubMed

Urbic, Tomaz

2016-10-01

A statistical model for a simple three-dimensional Mercedes-Benz model of water was used to study phase diagrams. This model on a simple level describes the thermal and volumetric properties of waterlike molecules. A molecule is presented as a soft sphere with four directions in which hydrogen bonds can be formed. Two neighboring waters can interact through a van der Waals interaction or an orientation-dependent hydrogen-bonding interaction. For pure water, we explored properties such as molar volume, density, heat capacity, thermal expansion coefficient, and isothermal compressibility and found that the volumetric and thermal properties follow the same trends with temperature as in real water and are in good general agreement with Monte Carlo simulations. The model exhibits also two critical points for liquid-gas transition and transition between low-density and high-density fluid. Coexistence curves and a Widom line for the maximum and minimum in thermal expansion coefficient divides the phase space of the model into three parts: in one part we have gas region, in the second a high-density liquid, and the third region contains low-density liquid.

Liquid-liquid critical point in a simple analytical model of water

NASA Astrophysics Data System (ADS)

Urbic, Tomaz

2016-10-01

A statistical model for a simple three-dimensional Mercedes-Benz model of water was used to study phase diagrams. This model on a simple level describes the thermal and volumetric properties of waterlike molecules. A molecule is presented as a soft sphere with four directions in which hydrogen bonds can be formed. Two neighboring waters can interact through a van der Waals interaction or an orientation-dependent hydrogen-bonding interaction. For pure water, we explored properties such as molar volume, density, heat capacity, thermal expansion coefficient, and isothermal compressibility and found that the volumetric and thermal properties follow the same trends with temperature as in real water and are in good general agreement with Monte Carlo simulations. The model exhibits also two critical points for liquid-gas transition and transition between low-density and high-density fluid. Coexistence curves and a Widom line for the maximum and minimum in thermal expansion coefficient divides the phase space of the model into three parts: in one part we have gas region, in the second a high-density liquid, and the third region contains low-density liquid.

A simple high-performance liquid chromatography for the determination of linezolid in human plasma and saliva.

PubMed

Hara, Shuuji; Uchiyama, Masanobu; Yoshinari, Masami; Matsumoto, Taichi; Jimi, Shiro; Togawa, Atsushi; Takata, Tohru; Takamatsu, Yasushi

2015-09-01

Linezolid is an antimicrobial agent for the treatment of multiresistant Gram-positive infections. A practical high-performance liquid chromatography method was developed for the determination of linezolid in human plasma and saliva. Linezolid and an internal standard (o-ethoxybenzamide) were extracted from plasma and saliva with ethyl acetate and analyzed on a Capcell Pak C18 MG column with UV detection at 254 nm. The calibration curve was linear through the range 0.5-50 µg/mL using a 200 μL sample volume. The intra- and interday precisions were all <6.44% for plasma and 5.60% for saliva. The accuracies ranged from 98.8 to 110% for both matrices. The mean recoveries of linezolid were 80.8% for plasma and 79.0% for saliva. This method was used to determine the plasma and saliva concentrations of linezolid in healthy volunteers who were orally administered a 600 mg dose of linezolid. Our liquid-liquid extraction procedure is easy and requires a small volume of plasma or saliva (200 μL). This small volume can be advantageous in clinical pharmacokinetic studies, especially if children participate. Copyright © 2015 John Wiley & Sons, Ltd.

Optimization of dispersive liquid-phase microextraction based on solidified floating organic drop combined with high-performance liquid chromatography for the analysis of glucocorticoid residues in food.

PubMed

Huang, Yuan; Zheng, Zhiqun; Huang, Liying; Yao, Hong; Wu, Xiao Shan; Li, Shaoguang; Lin, Dandan

2017-05-10

A rapid, simple, cost-effective dispersive liquid-phase microextraction based on solidified floating organic drop (SFOD-LPME) was developed in this study. Along with high-performance liquid chromatography, we used the developed approach to determine and enrich trace amounts of four glucocorticoids, namely, prednisone, betamethasone, dexamethasone, and cortisone acetate, in animal-derived food. We also investigated and optimized several important parameters that influenced the extraction efficiency of SFOD-LPME. These parameters include the extractant species, volumes of extraction and dispersant solvents, sodium chloride addition, sample pH, extraction time and temperature, and stirring rate. Under optimum experimental conditions, the calibration graph exhibited linearity over the range of 1.2-200.0ng/ml for the four analytes, with a reasonable linearity(r 2 : 0.9990-0.9999). The enrichment factor was 142-276, and the detection limits was 0.39-0.46ng/ml (0.078-0.23μg/kg). This method was successfully applied to analyze actual food samples, and good spiked recoveries of over 81.5%-114.3% were obtained. Copyright © 2017. Published by Elsevier B.V.

Simultaneous extraction and quantification of albendazole and triclabendazole using vortex-assisted hollow-fiber liquid-phase microextraction combined with high-performance liquid chromatography.

PubMed

Asadi, Mohammad; Haji Shabani, Ali Mohammad; Dadfarnia, Shayessteh

2016-06-01

A novel, simple, and rapid vortex-assisted hollow-fiber liquid-phase microextraction method was developed for the simultaneous extraction of albendazole and triclabendazole from various matrices before their determination by high-performance liquid chromatography with fluorescence detection. Several factors influencing the microextraction efficiency including sample pH, nature and volume of extraction solvent, ionic strength, vortex time, and sample volume were investigated and optimized. Under the optimal conditions, the limits of detection were 0.08 and 0.12 μg/L for albendazole and triclabendazole, respectively. The calibration curves were linear in the concentration ranges of 0.3-50.0 and 0.4-50.0 μg/L with the coefficients of determination of 0.9999 and 0.9995 for albendazole and triclabendazole, respectively. The interday and intraday relative standard deviations for albendazole and triclabendazole at three concentration levels (1.0, 10.0, and 30.0 μg/L) were in the range of 6.0-11.0 and 5.0-7.9%, respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, milk, honey, and urine samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of metabolite of nicergoline in human plasma by high-performance liquid chromatography and its application in pharmacokinetic studies.

PubMed

Zheng, Rong; Wu, Yi-Hong; Jiang, De-Xi; Zhang, Dan

2012-02-01

A fast, simple and sensitive high performance liquid chromatographic (HPLC) method has been developed for determination of 10 α -methoxy-6-methyl ergoline-8 β -methanol (MDL, a main metabolite of nicergoline) in human plasma. One-step liquid-liquid extraction (LLE) with diethyl ether was employed as the sample preparation method. Tizanidine hydrochloride was selected as the internal standard (IS). Analysis was carried out on a Diamonsil ODS column (150 mm×4.6 mm, 5 μm) using acetonitrile-ammonium acetate (0.1 mol/L) (15/85, v/v) as mobile phase at detection wavelength of 224 nm. The calibration curves were linear over the range of 2.288-73.2 ng/mL with a lower limit of quantitation (LLOQ) of 2.288 ng/mL. The intra- and inter-day precision values were below 13% and the recoveries were from 74.47% to 83.20% at three quality control levels. The method herein described was successfully applied in a randomized crossover bioequivalence study of two different nicergoline preparations after administration of 30 mg in 20 healthy volunteers.

A simple dual online ultra-high pressure liquid chromatography system (sDO-UHPLC) for high throughput proteome analysis.

PubMed

Lee, Hangyeore; Mun, Dong-Gi; Bae, Jingi; Kim, Hokeun; Oh, Se Yeon; Park, Young Soo; Lee, Jae-Hyuk; Lee, Sang-Won

2015-08-21

We report a new and simple design of a fully automated dual-online ultra-high pressure liquid chromatography system. The system employs only two nano-volume switching valves (a two-position four port valve and a two-position ten port valve) that direct solvent flows from two binary nano-pumps for parallel operation of two analytical columns and two solid phase extraction (SPE) columns. Despite the simple design, the sDO-UHPLC offers many advantageous features that include high duty cycle, back flushing sample injection for fast and narrow zone sample injection, online desalting, high separation resolution and high intra/inter-column reproducibility. This system was applied to analyze proteome samples not only in high throughput deep proteome profiling experiments but also in high throughput MRM experiments.

A simple sample preparation for simultaneous determination of chloramphenicol and its succinate esters in food products using high-performance liquid chromatography/high-resolution mass spectrometry.

PubMed

Amelin, Vasiliy; Korotkov, Anton

2017-02-01

A simple method is described for the determination of chloramphenicol and its succinate esters in food products. Examination of food products using high-performance liquid chromatography/high-resolution mass spectrometry showed the presence not only of chloramphenicol but also of its succinate forms. A scheme is proposed for determining chloramphenicol and its succinate esters (calculated as chloramphenicol) in meat (beef, pork, poultry), milk, liver, kidney, eggs, fish and honey. Analytes are extracted from a 1.0 g sample with 5 ml acetonitrile. It was found that using the method of standard addition and diluting the extract with water leads to the elimination of matrix effects and also eliminates errors associated with peak splitting due to the separate elution of the differing forms of the analyte. Validation results were satisfactory, with recoveries from 85% to 111% (meat, milk, liver, kidney, eggs, fish and honey) and a relative standard deviation (RSD) lower than 13% for spiked levels of 0.3, 1.0 and 5 µg kg - 1 . The limits of detection and quantification (calculated as chloramphenicol for all forms) were 0.1 and 0.3 µg kg - 1 , respectively. The RSD of the results of the analysis was < 10%. The duration of the analysis was less than 1 h.

Development and validation of high-performance liquid chromatography and high-performance thin-layer chromatography methods for the quantification of khellin in Ammi visnaga seed

PubMed Central

Kamal, Abid; Khan, Washim; Ahmad, Sayeed; Ahmad, F. J.; Saleem, Kishwar

2015-01-01

Objective: The present study was used to design simple, accurate and sensitive reversed phase-high-performance liquid chromatography RP-HPLC and high-performance thin-layer chromatography (HPTLC) methods for the development of quantification of khellin present in the seeds of Ammi visnaga. Materials and Methods: RP-HPLC analysis was performed on a C18 column with methanol: Water (75: 25, v/v) as a mobile phase. The HPTLC method involved densitometric evaluation of khellin after resolving it on silica gel plate using ethyl acetate: Toluene: Formic acid (5.5:4.0:0.5, v/v/v) as a mobile phase. Results: The developed HPLC and HPTLC methods were validated for precision (interday, intraday and intersystem), robustness and accuracy, limit of detection and limit of quantification. The relationship between the concentration of standard solutions and the peak response was linear in both HPLC and HPTLC methods with the concentration range of 10–80 μg/mL in HPLC and 25–1,000 ng/spot in HPTLC for khellin. The % relative standard deviation values for method precision was found to be 0.63–1.97%, 0.62–2.05% in HPLC and HPTLC for khellin respectively. Accuracy of the method was checked by recovery studies conducted at three different concentration levels and the average percentage recovery was found to be 100.53% in HPLC and 100.08% in HPTLC for khellin. Conclusions: The developed HPLC and HPTLC methods for the quantification of khellin were found simple, precise, specific, sensitive and accurate which can be used for routine analysis and quality control of A. visnaga and several formulations containing it as an ingredient. PMID:26681890

A novel fatty-acid-based in-tube dispersive liquid-liquid microextraction technique for the rapid determination of nonylphenol and 4-tert-octylphenol in aqueous samples using high-performance liquid chromatography-ultraviolet detection.

PubMed

Shih, Hou-Kuang; Shu, Ting-Yun; Ponnusamy, Vinoth Kumar; Jen, Jen-Fon

2015-01-07

In this study, a novel fatty-acid-based in-tube dispersive liquid-liquid microextraction (FA-IT-DLLME) technique is proposed for the first time and is developed as a simple, rapid and eco-friendly sample extraction method for the determination of alkylphenols in aqueous samples using high-performance liquid chromatography-ultraviolet detection (HPLC-UV). In this extraction method, medium-chain saturated fatty acids were investigated as a pH-dependent phase because they acted as either anionic surfactants or neutral extraction solvents based on the acid-base reaction caused solely by the adjustment of the pH of the solution. A specially designed home-made glass extraction tube with a built-in scaled capillary tube was utilized as the phase-separation device for the FA-IT-DLLME to collect and measure the separated extractant phase for analysis. Nonylphenol (NP) and 4-tert-octylphenol (4-tOP) were chosen as model analytes. The parameters influencing the FA-IT-DLLME were thoroughly investigated and optimized. Under the optimal conditions, the detector responses of NP and 4-tOP were linear in the concentration ranges of 5-4000 μg L(-1), with correlation coefficients of 0.9990 and 0.9996 for NP and 4-tOP, respectively. The limits of detection based on a signal-to-noise ratio of 3 were 0.7 and 0.5 μg L(-1), and the enrichment factors were 195 and 143 for NP and 4-tOP, respectively. The applicability of the developed method was demonstrated for the analysis of alkylphenols in environmental wastewater samples, and the recoveries ranged from 92.9 to 107.1%. The extraction process required less than 4 min and utilized only acids, alkalis, and fatty acids to achieve the extraction. The results demonstrated that the presented FA-IT-DLLME approach is highly cost-effective, simple, rapid and environmentally friendly in its sample preparation. Copyright © 2014 Elsevier B.V. All rights reserved.

Near-Infrared Scintillation of Liquid Argon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tilly, Elizabeth; Escobar, Carlos

2017-01-01

Liquid argon is well known to scintillate in the vacuum ultraviolet (VUV) range which is inherently difficult to detect. There has been recent evidence to suggest that it also emits near infrared (NIR) light. If this is the case, many large-scale time projection chambers and other similar detectors will be able to maximize light collection while minimizing cost. The goal of this project is to confirm and quantify this NIR emission. In order to accomplish this, an α-source was placed in a volume of highly purified liquid argon and observed using an infrared PMT with a filter excluding light withmore » wavelength <715 nm. Performing a simple counting experiment, there were indications of NIR scintillation. Further analysis is in progress.« less

Development and validation of an RP-HPLC method for the quantitation of odanacatib in rat and human plasma and its application to a pharmacokinetic study.

PubMed

Police, Anitha; Gurav, Sandip; Dhiman, Vinay; Zainuddin, Mohd; Bhamidipati, Ravi Kanth; Rajagopal, Sriram; Mullangi, Ramesh

2015-11-01

A simple, specific, sensitive and reproducible high-performance liquid chromatography (HPLC) assay method has been developed and validated for the estimation of odanacatib in rat and human plasma. The bioanalytical procedure involves extraction of odanacatib and itraconazole (internal standard, IS) from a 200 μL plasma aliquot with simple liquid-liquid extraction process. Chromatographic separation was achieved on a Symmetry Shield RP18 using an isocratic mobile phase at a flow rate of 0.7 mL/min. The UV detection wave length was 268 nm. Odanacatib and IS eluted at 5.5 and 8.6 min, respectively with a total run time of 10 min. Method validation was performed as per US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over a concentration range of 50.9-2037 ng/mL (r(2) = 0.994). The intra- and inter-day precisions were in the range of 2.06-5.11 and 5.84-13.1%, respectively, in rat plasma and 2.38-7.90 and 6.39-10.2%, respectively, in human plasma. The validated HPLC method was successfully applied to a pharmacokinetic study in rats. Copyright © 2015 John Wiley & Sons, Ltd.

Quantitative analysis of matrine in liquid crystalline nanoparticles by HPLC.

PubMed

Peng, Xinsheng; Li, Baohong; Hu, Min; Ling, Yahao; Tian, Yuan; Zhou, Yanxing; Zhou, Yanfang

2014-01-01

A reversed-phase high-performance liquid chromatographic method has been developed to quantitatively determine matrine in liquid crystal nanoparticles. The chromatographic method is carried out using an isocratic system. The mobile phase was composed of methanol-PBS(pH6.8)-triethylamine (50 : 50 : 0.1%) with a flow rate of 1 mL/min with SPD-20A UV/vis detector and the detection wavelength was at 220 nm. The linearity of matrine is in the range of 1.6 to 200.0  μ g/mL. The regression equation is y = 10706x - 2959 (R (2) = 1.0). The average recovery is 101.7%; RSD = 2.22%  (n = 9). This method provides a simple and accurate strategy to determine matrine in liquid crystalline nanoparticle.

Stir bar sorptive extraction and high performance liquid chromatographic determination of carvedilol in human serum using two different polymeric phases and an ionic liquid as desorption solvent.

PubMed

Talebpour, Zahra; Taraji, Maryam; Adib, Nuoshin

2012-05-04

This article presents a method employing stir bar coated with a film of poly (methyl methacrylate/ethyleneglycol dimethacrylate) (PA-EG) and polydimethylsiloxane (PDMS) in combination with liquid desorption (LD) using ionic liquid, followed by high performance liquid chromatography (HPLC) equipped with ultraviolet (UV) detection for the determination of carvedilol in human serum samples. Stir bar sorptive extraction (SBSE) variables, such as desorption and extraction time and temperature, desorption solvent and pH of the matrix were optimized, in order to achieve suitable analytical sensitivity in a short period of time. Also, the concentration effect of 1-methyl-3-octylimidazolium tetrafluoroborate [Omim][BF4] ionic liquid on the efficiency of LD was investigated. A comparison between PA-EG/SBSE and PDMS/SBSE was made by calculating the experimental recovery and partition coefficient (K), where PA-EG phase demonstrated to be an excellent alternative for the enrichment of the carvedilol from serum samples. The effect of [Omim][BF4] on carryover was studied and no carryover was observed. Under optimized experimental conditions, the analytical performance showed excellent linear dynamic range, with correlation coefficients higher than 0.999 and limits of detection and quantification of 0.3 and 1.0 ng mL(-1), respectively. Intra- and inter-day recovery ranged from 94 to 103% and the coefficients of variations were less than 3.2%. The proposed method was shown to be simple, highly sensitive and suitable for the measurement of trace concentration levels of carvedilol in biological fluid media. Copyright © 2012 Elsevier B.V. All rights reserved.

Binary Solvents Dispersive Liquid-Liquid Microextraction (BS-DLLME) Method for Determination of Tramadol in Urine Using High-Performance Liquid Chromatography.

PubMed

Kiarostami, Vahid; Rouini, Mohamad-Reza; Mohammadian, Razieh; Lavasani, Hoda; Ghazaghi, Mehri

2014-02-03

Tramadol is an opioid, synthetic analog of codeine and has been used for the treatment of acute or chronic pain may be abused. In this work, a developed Dispersive liquid liquid microextraction (DLLME) as binary solvents-based dispersive liquid-liquid microextraction (BS-DLLME) combined with high performance liquid chromatography (HPLC) with fluorescence detection (FD) was employed for determination of tramadol in the urine samples. This procedure involves the use of an appropriate mixture of binary extraction solvents (70 μL CHCl3 and 30 μL ethyl acetate) and disperser solvent (600 μL acetone) for the formation of cloudy solution in 5 ml urine sample comprising tramadol and NaCl (7.5%, w/v). After centrifuging, the small droplets of extraction solvents were precipitated. In the final step, the HPLC with fluorescence detection was used for determination of tramadol in the precipitated phase. Various factors on the efficiency of the proposed procedure were investigated and optimized. The detection limit (S/N = 3) and quantification limit (S/N = 10) were found 0.2 and 0.9 μg/L, respectively. The relative standard deviations (RSD) for the extraction of 30 μg L of tramadol was found 4.1% (n = 6). The relative recoveries of tramadol from urine samples at spiking levels of 10, 30 and 60 μg/L were in the range of 95.6 - 99.6%. Compared with other methods, this method provides good figures of merit such as good repeatability, high extraction efficiency, short analysis time, simple procedure and can be used as microextraction technique for routine analysis in clinical laboratories.

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.

A high-performance liquid chromatography-electronic circular dichroism online method for assessing the absolute enantiomeric excess and conversion ratio of asymmetric reactions

NASA Astrophysics Data System (ADS)

Zhang, Xiang; Wang, Mingchao; Li, Li; Yin, Dali

2017-03-01

Asymmetric reactions often need to be evaluated during the synthesis of chiral compounds. However, traditional evaluation methods require the isolation of the individual enantiomer, which is tedious and time-consuming. Thus, it is desirable to develop simple, practical online detection methods. We developed a method based on high-performance liquid chromatography-electronic circular dichroism (HPLC-ECD) that simultaneously analyzes the material conversion ratio and absolute optical purity of each enantiomer. In particular, only a reverse-phase C18 column instead of a chiral column is required in our method because the ECD measurement provides a g-factor that describes the ratio of each enantiomer in the mixtures. We used our method to analyze the asymmetric hydrosilylation of β-enamino esters, and we discussed the advantage, feasibility, and effectiveness of this new methodology.

Simultaneous determination of vancomycin and ceftazidime in cerebrospinal fluid in craniotomy patients by high-performance liquid chromatography.

PubMed

Ye, Guangming; Cai, Xuejian; Wang, Biao; Zhou, Zhongxian; Yu, Xiaohua; Wang, Weibin; Zhang, Jiandong; Wang, Yuhai; Dong, Jierong; Jiang, Yunyun

2008-11-04

A simple, accurate and rapid method for simultaneous analysis of vancomycin and ceftazidime in cerebrospinal fluid (CSF), utilizing high-performance liquid chromatography (HPLC), has been developed and thoroughly validated to satisfy strict FDA guidelines for bioanalytical methods. Protein precipitation was used as the sample pretreatment method. In order to increase the accuracy, tinidazole was chosen as the internal standard. Separation was achieved on a Diamonsil C18 column (200 mm x 4.6mm I.D., 5 microm) using a mobile phase composed of acetonitrile and acetate buffer (pH 3.5) (8:92, v/v) at room temperature (25 degrees C), and the detection wavelength was 240 nm. All the validation data, such as accuracy, precision, and inter-day repeatability, were within the required limits. The method was applied to determine vancomycin and ceftazidime concentrations in CSF in five craniotomy patients.

[Simultaneous determination of six synthetic sweeteners in food by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Liu, Xiaoxi; Ding, Li; Liu, Jinxia; Zhang, Ying; Huang, Zhiqiang; Wang, Libing; Chen, Bo

2010-11-01

A simple and sensitive method for the determination of six synthetic sweeteners (sodium cyclamate, saccharin sodium, acesulfame-K, aspartame, alitame and neotame) in food was developed. The synthetic sweeteners were extracted by methanol-water (1 : 1, v/v). The extract was separated on a C18 column using 0.1% (v/v) formic acid-5 mmol/L ammonium formate/acetonitrile as mobile phase, and then detected by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) using multiple reaction monitoring (MRM) mode. The good linearities (r > 0.998) were achieved for all the analytes over the range of 20-500 microg/L. The recoveries obtained ranged from 81.3% to 106.0% at three spiked concentrations, with the relative standard deviations lower than 11%. The established method has been successfully applied to the determination of synthetic sweeteners in food.

Cloud point extraction and determination of trace trichlorfon by high performance liquid chromatography with ultraviolet-detection based on its catalytic effect on benzidine oxidizing.

PubMed

Zhu, Hai-Zhen; Liu, Wei; Mao, Jian-Wei; Yang, Ming-Min

2008-04-28

4-Amino-4'-nitrobiphenyl, which is formed by catalytic effect of trichlorfon on sodium perborate oxidizing benzidine, is extracted with a cloud point extraction method and then detected using a high performance liquid chromatography with ultraviolet detection (HPLC-UV). Under the optimum experimental conditions, there was a linear relationship between trichlorfon in the concentration range of 0.01-0.2 mgL(-1) and the peak areas of 4-amino-4'-nitrobiphenyl (r=0.996). Limit of detection was 2.0 microgL(-1), recoveries of spiked water and cabbage samples ranged between 95.4-103 and 85.2-91.2%, respectively. It was proved that the cloud point extraction (CPE) method was simple, cheap, and environment friendly than extraction with organic solvents and had more effective extraction yield.

Rapid determination of vitellogenin in fish plasma by anion exchange high performance liquid chromatography using postcolumn fluorescence derivatization with o-phthalaldehyde.

PubMed

Wu, Cuiqin; Yuan, Dongxing; Liu, Baomin

2006-12-01

An analytical method involving anion exchange high performance liquid chromatographic determination of vitellogenin (Vtg) in fish plasma after postcolumn fluorescence derivatization with o-phthalaldehyde (OPA) was developed. The retention time of Vtg was about 11 min. The reagent variables for derivatization were optimized. The fluorophore was excited at 335 nm and detected at 435 nm. A calibration curve was established ranging from 0.13 to 11.28 microg. The determination limit of Vtg was found to be as low as 0.13 microg. The spiked recovery was 93.6% and interassay variability was less than 4%. The method developed was used to determine Vtg in fish plasma obtained from red sea bream (Pagrosomus major), black porgy (Sparus macrocephalus) and skew band grunt (Hapalogenys nitens), without complicated sample pretreatment. The results confirmed that the method showed advantages of being simple, rapid, reproducible and sensitive.

[Detection of the preservative chlorphenesin in cosmetics by high-performance liquid chromatography].

PubMed

Ikarashi, Yoshiaki; Miyazawa, Norimasa; Shimamura, Kimio; Sato, Nobuo; Yoshizawa, Ken-ichi; Hayashi, Masahito; Takano, Katsuhiro; Miyamoto, Michiko; Kojima, Takashi; Sakaguchi, Hiroshi; Fujiio, Makiko

2009-01-01

A simple determination method for preservative chlorphenesin in cosmetics was developed. Cosmetic samples were dissolved in methanol. The sample solution was analyzed by high-performance liquid chromatography (HPLC) with ODS column, using water-methanol (55:45) or water-acetonitrile (3:1) adjusted to pH 2.5 with phosphoric acid as the mobile phase. Chlorphenesin was detected with ultraviolet light detection at 280 nm. A linear relation was obtained between the peak areas and the concentrations of chlorphenesin in the range of 1-500 microg/ml. The determination limit of chlorphenesin was 1-2 microg/ml. Recoveries of chlorphenesin spiked in lotion and milky lotion at the levels of 0.03% and 0.3% were 98.8-100.0%. This method was applied for cosmetics including 0.03% and 0.3% of chlorphenesin and their content corresponded with the determined values.

On electro-hydrodynamic effects over liquids under influence of corona discharge

NASA Astrophysics Data System (ADS)

Bychkov, V. L.; Abakumov, V. I.; Bikmukhametova, A. R.; Chernikov, V. A.; Safronenkov, D. A.

2018-03-01

Electrohydrodynamic effects over liquids under high voltage electrode are considered in experiments with corona discharge. Simple theory is applied for description of a funnel appearance over a liquid is presented. New types of electrohydrodynamic instabilities are revealed.

Salting-out assisted liquid-liquid extraction with the aid of experimental design for determination of benzimidazole fungicides in high salinity samples by high-performance liquid chromatography.

PubMed

Wen, Yingying; Li, Jinhua; Yang, Fangfang; Zhang, Weiwei; Li, Weiran; Liao, Chunyang; Chen, Lingxin

2013-03-15

A novel method for the simultaneous separation and determination of four benzimidazole fungicides (i.e., carbendazim, fuberidazole, thiophanate-methyl and thiophanate) in high salinity samples was developed by using salting-out assisted liquid-liquid extraction (SALLE) via water-miscible acetonitrile as the extractant coupled with high-performance liquid chromatography. Box-Behnken design and response surface were employed to assist the optimization of SALLE conditions, including volume of salting-out solvent, the pH of sample solution and salting-out solvent as variable factors. The optimal salting-out parameters were obtained as follows: 2 mL of acetonitrile was added to 2 mL of sample solution with pH=4 and then 2 mL salting-out solvent containing 5 mol L(-1) sodium chloride at a pH of 7 was added to the solution for extraction. This procedure afforded a convenient and cost-saving operation with good cleanup ability for the benzimidazole fungicides, such as good linear relationships (R>0.996) between peak area and concentration from 2.5 ng mL(-1) to 500 ng mL(-1), low limits of detection between 0.14 ng mL(-1) and 0.38 ng mL(-1) and the intra-day precisions of retention time below 1.0%. The method recoveries obtained at fortified three concentrations for three seawater samples ranged from 60.4% to 99.1%. The simple, rapid and eco-benign SALLE based method proved potentially applicable for trace benzimidazole fungicides analysis in high salinity samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Indirect enantioseparation of fluoxetine in mouse serum by derivatization with 1R-(-)-menthyl chloroformate followed by ultra high performance liquid chromatography and quadrupole time-of-flight mass spectrometry.

PubMed

Zhao, Jing; Jin, Yan; Shin, Yujin; Jeong, Kyung Min; Lee, Jeongmi

2016-03-01

Here we describe a simple and sensitive analytical method for the enantioselective quantification of fluoxetine in mouse serum using ultra high performance liquid chromatography with quadrupole time-of-flight mass spectrometry. The sample preparation method included a simple deproteinization with acetonitrile in 50 μL of serum, followed by derivatization of the extracts in 50 μL of 2 mM 1R-(-)-menthyl chloroformate at 45ºC for 55 min. These conditions were statistically optimized through response surface methodology using a central composite design. Under the optimized conditions, neither racemization nor kinetic resolution occurred. The derivatized diastereomers were readily resolved on a conventional sub-2 μm C18 column under a simple gradient elution of aqueous methanol containing 0.1% formic acid. The established method was validated and found to be linear, precise, and accurate over the concentration range of 5.0-1000.0 ng/mL for both R and S enantiomers (r(2) > 0.993). Stability tests of the prepared samples at three different concentration levels showed that the R- and S-fluoxetine derivatives were relatively stable for 48 h. No significant matrix effects were observed. Last, the developed method was successfully used for enantiomeric analysis of real serum samples collected at a number of time points from mice administered with racemic fluoxetine. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High performance liquid chromatography for simultaneous determination of xipamide, triamterene and hydrochlorothiazide in bulk drug samples and dosage forms.

PubMed

Abd El-Hay, Soad S; Hashem, Hisham; Gouda, Ayman A

2016-03-01

A novel, simple and robust high-performance liquid chromatography (HPLC) method was developed and validated for simultaneous determination of xipamide (XIP), triamterene (TRI) and hydrochlorothiazide (HCT) in their bulk powders and dosage forms. Chromatographic separation was carried out in less than two minutes. The separation was performed on a RP C-18 stationary phase with an isocratic elution system consisting of 0.03 mol L(-1) orthophosphoric acid (pH 2.3) and acetonitrile (ACN) as the mobile phase in the ratio of 50:50, at 2.0 mL min(-1) flow rate at room temperature. Detection was performed at 220 nm. Validation was performed concerning system suitability, limits of detection and quantitation, accuracy, precision, linearity and robustness. Calibration curves were rectilinear over the range of 0.195-100 μg mL(-1) for all the drugs studied. Recovery values were 99.9, 99.6 and 99.0 % for XIP, TRI and HCT, respectively. The method was applied to simultaneous determination of the studied analytes in their pharmaceutical dosage forms.

[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.

Analysis of potential migrants from plastic materials in milk by liquid chromatography-mass spectrometry with liquid-liquid extraction and low-temperature purification.

PubMed

Bodai, Zsolt; Szabó, Bálint Sámuel; Novák, Márton; Hámori, Susanne; Nyiri, Zoltán; Rikker, Tamás; Eke, Zsuzsanna

2014-10-15

A simple and fast analytical method was developed for the determination of six UV stabilizers (Cyasorb UV-1164, Tinuvin P, Tinuvin 234, Tinuvin 326, Tinuvin 327, and Tinuvin 1577) and five antioxidants (Irgafos 168, Irganox 1010, Irganox 3114, Irganox 3790, and Irganox 565) in milk. For sample preparation liquid-liquid extraction with low-temperature purification combined with centrifugation was used to remove fats, proteins, and sugars. After the cleanup step, the sample was analyzed with high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). External standard and matrix calibrations were tested. External calibration proved to be acceptable for Tinuvin P, Tinuvin 234, Tinuvin 326, Tinuvin 327, Irganox 3114, and Irganox 3790. The method was successfully validated with matrix calibration for all compounds. Method detection limits were between 0.25 and 10 μg/kg. Accuracies ranged from 93 to 109%, and intraday precisions were <13%.

[Analysis of the preservative chlorphenesin in cosmetics by high performance liquid chromatography].

PubMed

Zhu, Huijuan; Zhang, Weiqiang; Yang, Yanwei; Zhu, Ying

2014-01-01

An analytical method was developed for the determination of the preservative of chlorphenesin in cosmetics by high performance liquid chromatography (HPLC). A C18 column (250 mm x 4.6 mm, 5 microm) and a photodiode array detector were used. The mobile phase was methanol-water (55:45, v/v) with a flow rate of 1.0 mL/min. The detection wavelength was set at 280 nm and the column temperature was 25 degrees C. The limit of detection was 3 ng. A good linear relationship was obtained between the peak area and the mass concentration of chlorphenesin in the range of 1 - 500 mg/L and the correlation coefficient was 1.000 0. The recoveries of chlorphenesin at different spiked levels were 99.0% - 103% with the relative standard deviations (RSD) < or = 1.2%. Interference test and sample test were also applied meanwhile and validation experiments were performed by three laboratories. The method is simple, sensitive, accurate, stable and suitable for the determination of chlorphenesin in cosmetics.

Development and validation of stability indicating method for the quantitative determination of venlafaxine hydrochloride in extended release formulation using high performance liquid chromatography

PubMed Central

Kaur, Jaspreet; Srinivasan, K. K.; Joseph, Alex; Gupta, Abhishek; Singh, Yogendra; Srinivas, Kona S.; Jain, Garima

2010-01-01

Objective: Venlafaxine,hydrochloride is a structurally novel phenethyl bicyclic antidepressant, and is usually categorized as a serotonin–norepinephrine reuptake inhibitor (SNRI) but it has been referred to as a serotonin–norepinephrine–dopamine reuptake inhibitor. It inhibits the reuptake of dopamine. Venlafaxine HCL is widely prescribed in the form of sustained release formulations. In the current article we are reporting the development and validation of a fast and simple stability indicating, isocratic high performance liquid chromatographic (HPLC) method for the determination of venlafaxine hydrochloride in sustained release formulations. Materials and Methods: The quantitative determination of venlafaxine hydrochloride was performed on a Kromasil C18 analytical column (250 × 4.6 mm i.d., 5 μm particle size) with 0.01 M phosphate buffer (pH 4.5): methanol (40: 60) as a mobile phase, at a flow rate of 1.0 ml/min. For HPLC methods, UV detection was made at 225 nm. Results: During method validation, parameters such as precision, linearity, accuracy, stability, limit of quantification and detection and specificity were evaluated, which remained within acceptable limits. Conclusions: The method has been successfully applied for the quantification and dissolution profiling of Venlafaxine HCL in sustained release formulation. The method presents a simple and reliable solution for the routine quantitative analysis of Venlafaxine HCL. PMID:21814426

Magnetic Solid Phase Extraction Based on Oleic Acid Coated Fe3O4 for the Determination of Benzo[α]pyrene in Cigarette Smoke Coupled with High-Performance Liquid Chromatography.

PubMed

Feng, Shouai; Wei, Kang; Tian, Zhaofu; Li, Xiaolan; Meng, Dongling; Liao, Wenlong; Miao, Mingming; Yang, Yaling

2016-07-29

In this work, a simple and effective method based on magnetic solid-phase extraction combined with high-performance liquid chromatography was developed for the determination of benzo[α]pyrene (BaP) in cigarette smoke. Oleic acid coated Fe 3 O 4 (Fe 3 O 4 -OA) was synthesized and directly used as an efficient sorbent for the first time in magnetic solid-phase extraction (MSPE) procedure for the clean-up of BaP in cigarette smoke extracts. The synthesized Fe 3 O 4 -OA was characterized by transmission electron microscopy, X-ray diffraction and Fourier transformed infrared spectroscopy. The extraction via Fe 3 O 4 -OA was dispersed in the extracts of cigarette smoke followed by the magnetic isolation, acetonitrile-tetrahydrofuran (ACN-THF; v/v = 9:1) was used for desorption of the analyte. The effects of important parameters such as the amount of adsorbent, solution pH, the content of acetonitrile, temperature and sorption time were investigated. The method showed good linearity for the determination of BaP in the concentration range of 0.5-50 ng mL -1 with a regression coefficient (R 2 ) of 0.9987. The limit of detection and limit of quantification for BaP were obtained to be 0.12 and 0.41 ng mL -1 , respectively. The mean recoveries were in the range from 81.0% to 97.6% at low, medium, high spiked levels, and the relative standard deviations were in the range of 2.7-6.8%. Combined with high-performance liquid chromatography and fluorescence detection, a simple and effective method was developed for the analysis of BaP in cigarette smoke. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Liquid-fuel valve with precise throttling control

NASA Technical Reports Server (NTRS)

Mcdougal, A. R.; Porter, R. N.; Riebling, R. W.

1971-01-01

Prototype liquid-fuel valve performs on-off and throttling functions in vacuum without component cold-welding or excessive leakage. Valve design enables simple and rapid disassembly and parts replacement and operates with short working stroke, providing maximum throttling sensitivity commensurate with good control.

Determination of sudan dyes in red wine and fruit juice using ionic liquid-based liquid-liquid microextraction and high-performance liquid chromatography.

PubMed

Sun, Shuo; Wang, Ying; Yu, Wenzhi; Zhao, Tianqi; Gao, Shiqian; Kang, Mingqin; Zhang, Yupu; Zhang, Hanqi; Yu, Yong

2011-07-01

The liquid-liquid microextraction (LLME) was developed for extracting sudan dyes from red wine and fruit juice. Room temperature ionic liquid was used as the extraction solvent. The target analytes were determined by high-performance liquid chromatography. The extraction parameters were optimized. The optimal conditions are as follows: volume of [C(6)MIM][PF(6)] 50 μL; the extraction time 10 min; pH value of the sample solution 7.0; NaCl concentration in sample solution 5%. The extraction recoveries for the analytes in red wine and fruit samples are 86.79-108.28 and 68.54-85.66%, whereas RSDs are 1.42-5.12 and 1.43-6.19%, respectively. The limits of detection and quantification were 0.428 and 1.426 ng/mL for sudan I, 0.938 and 3.127 ng/mL for sudan II, 1.334 and 4.445 ng/mL for sudan III, 1.454 and 4.846 ng/mL for sudan IV, respectively. Compared with conventional liquid-liquid extraction (CLLE) and ultrasonic extraction (UE), when LLME was applied, the sample amount was less (LLME: 4 mL; CLLE: 10 mL; UE: 10 mL), the extraction time was shorter (LLME: 15 min; CLLE: 110 min; UE: 50 min) and the extraction solvent amount was less (LLME: 0.05 mL IL; CLLE: 15 mL hexane; UE: 20 mL hexane). The proposed method offers a simple, rapid and efficient sample preparation for determining sudan dyes in red wine and fruit juice samples. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Steviol quantification at the picomole level by high-performance liquid chromatography.

PubMed

Minne, Veerle J Y; Compernolle, Frans; Toppet, Suzanne; Geuns, Jan M C

2004-05-05

A simple and highly sensitive reversed-phase high-performance liquid chromatographic method (RP-HPLC) has been developed for the determination of steviol (SV) using dihydroisosteviol (DHISV) as an internal standard (IS). SV and DHISV were derivatized by reaction of the acids with 4-(bromomethyl)-7-methoxycoumarin in an aprotic solvent (DMF or acetone). The resulting ester derivatives were separated on an ODS column (250 x 4.6 mm i.d., 5 microm particle size) using fluorescence detection with excitation at 321 nm and emission at 391 nm. The mobile phase consisted of acetonitrile/water (80:20 v/v) with a flow rate of 1 mL min(-)(1). A linear relationship was observed for concentrations between 0.5 and 50 microg/mL of SV, and the detection limit was 100 pg. For application of this method to samples of beer fortified with stevioside, a simple procedure for extraction of the beer with diethyl ether and derivatization in DMF was applied. Whereas beer samples spiked with SV gave a linear response over the range 0.1-15 microg/mL beer, no SV could be detected in beer samples enriched in stevioside that had been stored for over 3 years. The application of the method to plant samples involved preparation of an acid fraction containing the SV analyte, derivatization, and sample cleanup using small silica columns and thin-layer chromatography. A sensitive determination of 594 ng of steviol present in 100 mg of dry plant material was performed with high precision and accuracy.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by high-performance liquid chromatography with ultraviolet detection and liquid chromatography-tandem mass spectrometry for the determination of triclosan and 2,4-dichlorophenol in water samples.

PubMed

Zheng, Cao; Zhao, Jing; Bao, Peng; Gao, Jin; He, Jin

2011-06-24

A novel, simple and efficient dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) technique coupled with high-performance liquid chromatography with ultraviolet detection (HPLC-UV) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of triclosan and its degradation product 2,4-dichlorophenol in real water samples. The extraction solvent used in this work is of low density, low volatility, low toxicity and proper melting point around room temperature. The extractant droplets can be collected easily by solidifying it at a lower temperature. Parameters that affect the extraction efficiency, including type and volume of extraction solvent and dispersive solvent, salt effect, pH and extraction time, were investigated and optimized in a 5 mL sample system by HPLC-UV. Under the optimum conditions (extraction solvent: 12 μL of 1-dodecanol; dispersive solvent: 300 of μL acetonitrile; sample pH: 6.0; extraction time: 1 min), the limits of detection (LODs) of the pretreatment method combined with LC-MS/MS were in the range of 0.002-0.02 μg L(-1) which are lower than or comparable with other reported approaches applied to the determination of the same compounds. Wide linearities, good precisions and satisfactory relative recoveries were also obtained. The proposed technique was successfully applied to determine triclosan and 2,4-dichlorophenol in real water samples. Copyright © 2011 Elsevier B.V. All rights reserved.

[Simultaneous determination of 7 arsenic species in chicken muscle and chicken liver with high performance liquid chromatography-inductively coupled plasma mass spectrometry].

PubMed

Yang, Lijun; Hu, Qiaoru; Guo, Wei; Liu, Yumin; Song, Xiaohua; Zhang, Pengcheng

2011-05-01

A method for the simultaneous determination of 7 arsenic species was developed with high performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The sample was extracted with artificial gastric juice. The HPLC separation was performed on an anion analytical column utilizing a gradient elution program of ammonium carbonate and water as the mobile phase. Identification and quantification were achieved by ICP-MS. Good linearities of 7 arsenic species were observed in the range from 1 microg/kg to 50 microg/kg with the correlation coefficients greater than 0.999. The average recoveries of 7 arsenic species spiked at the three levels of 1, 2 and 10 microg/kg ranged from 84.3% to 106.6% with the relative standard deviations of 1.4%-4.2%. The quantification limits of 7 arsenic species were 1 microg/kg. The method was proved to be good reproducibility, high sensitivity and simple preprocessing. This method is suitable for the simultaneous determination of 7 arsenic species in chicken muscle and chicken liver.

Dithizone-functionalized solid phase extraction-displacement elution-high performance liquid chromatography-inductively coupled plasma mass spectrometry for mercury speciation in water samples.

PubMed

Yin, Yong-guang; Chen, Ming; Peng, Jin-feng; Liu, Jing-fu; Jiang, Gui-bin

2010-06-15

A novel and simple solid phase extraction (SPE)-high performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) method was developed for determination of inorganic mercury (IHg), methylmercury MeHg and ethylmercury (EtHg) in water samples in the present work. The procedure involves pre-functionalization of the commercially available C18 SPE column with dithizone, loading water sample, displacement elution of mercury species by Na(2)S(2)O(3) solution, followed by HPLC-ICP-MS determination. Characterization and optimization of operation parameters of this new SPE procedure were discussed, including eluting reagent selection, concentration of eluting reagent, volume of eluting reagent, effect of NaCl and humic acid in sample matrix. At optimized conditions, the detection limits of mercury species for 100mL water sample were about 3ngL(-1) and the average recoveries were 93.7, 83.4, and 71.7% for MeHg, IHg and EtHg, respectively, by spiking 0.2microgL(-1) mercury species into de-ion water. Stability experiment reveals that both the dithizone-functionalized SPE cartridge and the mercury species incorporated were stable in the storage procedure. These results obtained demonstrate that SPE-HPLC-ICP-MS is a simple and sensitive technique for the determination of mercury species at trace level in water samples with high reproducibility and accuracy.

Challenges for Detecting Valproic Acid in a Nontargeted Urine Drug Screening Method.

PubMed

Pope, Jeffrey D; Black, Marion J; Drummer, Olaf H; Schneider, Hans G

2017-08-01

Valproic acid (VPA) is a widely prescribed medicine, and acute toxicity is possible. As such, it should be included in any nontargeted urine drug screening method. In many published liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS) methods, VPA is usually measured using a pseudo-multiple reaction monitoring (MRM) transition. We investigate a simple ultra-high-performance liquid chromatography-quadrupole time-of-flight (QTof) approach to detect the presence of VPA with more confidence. Three commercially sourced VPA metabolites were characterized and added to a nontargeted high-resolution MS urine drug screening method. All analyses were performed on a Waters Xevo G2-XS LC-QTof in negative electrospray ionization mode. The mass detector was operated in MS mode, and data were processed with UNIFI software. Sixty-eight patient urine samples, which were previously identified by a well-established gas chromatography-MS method as containing VPA, were analyzed on the Waters Xevo G2-XS LC-QTof, to validate this approach. VPA metabolite standards were characterized, and their detection data were added to the broad drug screening library. VPA metabolites were readily detectable in the urine of patients taking VPA. The inclusion of characterized VPA metabolites provides a simple and reliable method enabling the detection of VPA in nontargeted urine drug screening.

A Simple High-Performance Liquid Chromatography for Determining Lapatinib and Erlotinib in Human Plasma.

PubMed

Ohgami, Masahiro; Homma, Masato; Suzuki, Yoshiharu; Naito, Kanako; Yamada, Motoko; Mitsuhashi, Shoichi; Fujisawa, Fumie; Kojima, Hiroshi; Kaburagi, Takayuki; Uchiumi, Keiko; Yamada, Yutaka; Bando, Hiroko; Hara, Hisato; Takei, Keiji

2016-12-01

Lapatinib and erlotinib are used for cancer treatment, showing large interindividual variability. Therapeutic drug monitoring may be useful for assessing the clinical outcomes and adverse events. A simple high-performance liquid chromatography UV method was developed for the determination of lapatinib and erlotinib in human plasma. An aliquot of plasma sample spiked with internal standard was treated with acetonitrile to precipitate the proteins. Lapatinib and erlotinib were separated on an octadecylsilyl silica gel column using a mobile phase consisting of acetonitrile, methanol, water, and trifluoroacetic acid (26:26:48:0.1) pumped at a flow rate of 1.0 mL/min. The detection wavelength was set at 316 nm. The calibration curves for lapatinib and erlotinib were linear (r = 0.9999) in the range of 0.125-8.00 mcg/mL. The extraction recoveries for both lapatinib and erlotinib at the plasma concentration of 0.125-8.00 mcg/mL were higher than 89.9% with coefficients of variation less than 3.5%. The coefficients of variation for intraday and interday assays of lapatinib and erlotinib were less than 5.1% and 6.1%, respectively. The present method can be used for blood concentration monitoring for lapatinib or erlotinib in exactly the same conditions.

Quantitation of polyamines in cultured cells and tissue homogenates by reversed-phase high-performance liquid chromatography of their benzoyl derivatives.

PubMed

Verkoelen, C F; Romijn, J C; Schroeder, F H; van Schalkwijk, W P; Splinter, T A

1988-04-08

A rapid and simple method, originally described by Redmond and Tseng [J. Chromatogr., 170 (1979) 479] was applied to the analysis of di- and polyamines in cultured human tumour cells and human tumour xenografts. Optimization of the procedures and evaluation of the characteristic features of the assay are described. The (modified) procedure employs precolumn derivatization with benzoyl chloride, extraction of the derivatives by chloroform, separation by reversed-phase high-performance liquid chromatography under isocratic conditions and detection by ultraviolet absorbance measurement at 229 nm. The complete analysis was accomplished within 10 min per sample. The detection limit was ca. 1 pmol. The intra- and inter-assay coefficients of variation were 2.5-4.4% and 3.4-13.1%, respectively. The presence of well known inhibitors of polyamine biosynthesis, such as DL-alpha-difluoromethylornithine and methylglyoxal bis(guanylhydrazone), did not interfere with the assay, and disturbance by cyclohexylamine could be avoided by changing the polarity of the mobile phase. The method proved to be very suitable because it is rapid, simple, requires a minimum of sample pretreatment, and still provides sufficient sensitivity to quantitate polyamines in relatively small amounts of cells (10(5) cells) or tumour tissues (less than 1 mg), even after treatment with inhibitors of polyamine biosynthesis.

Sensitivity enhancement by chromatographic peak concentration with ultra-high performance liquid chromatography-nuclear magnetic resonance spectroscopy for minor impurity analysis.

PubMed

Tokunaga, Takashi; Akagi, Ken-Ichi; Okamoto, Masahiko

2017-07-28

High performance liquid chromatography can be coupled with nuclear magnetic resonance (NMR) spectroscopy to give a powerful analytical method known as liquid chromatography-nuclear magnetic resonance (LC-NMR) spectroscopy, which can be used to determine the chemical structures of the components of complex mixtures. However, intrinsic limitations in the sensitivity of NMR spectroscopy have restricted the scope of this procedure, and resolving these limitations remains a critical problem for analysis. In this study, we coupled ultra-high performance liquid chromatography (UHPLC) with NMR to give a simple and versatile analytical method with higher sensitivity than conventional LC-NMR. UHPLC separation enabled the concentration of individual peaks to give a volume similar to that of the NMR flow cell, thereby maximizing the sensitivity to the theoretical upper limit. The UHPLC concentration of compound peaks present at typical impurity levels (5.0-13.1 nmol) in a mixture led to at most three-fold increase in the signal-to-noise ratio compared with LC-NMR. Furthermore, we demonstrated the use of UHPLC-NMR for obtaining structural information of a minor impurity in a reaction mixture in actual laboratory-scale development of a synthetic process. Using UHPLC-NMR, the experimental run times for chromatography and NMR were greatly reduced compared with LC-NMR. UHPLC-NMR successfully overcomes the difficulties associated with analyses of minor components in a complex mixture by LC-NMR, which are problematic even when an ultra-high field magnet and cryogenic probe are used. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of Combustion Tube for Gaseous, Liquid, and Solid Fuels to Study Flame Acceleration and DDT

NASA Astrophysics Data System (ADS)

Graziano, Tyler J.

An experimental combustion tube of 20 ft. in length and 10.25 in. in internal diameter was designed and fabricated in order to perform combustion tests to study deflagration rates, flame acceleration, and the possibility of DDT. The experiment was designed to allow gaseous, liquid, or solid fuels, or any combination of the three to produce a homogenous fuel/air mixture within the tube. Combustion tests were initiated with a hydrogen/oxygen torch igniter and the resulting flame behavior was measured with high frequency ion probes and pressure transducers. Tests were performed with a variety of gaseous and liquid fuels in an unobstructed tube with a closed ignition end and open muzzle. The flame performance with the gaseous fuels is loosely correlated with the expansion ratio, while there is a stronger correlation with the laminar flame speed. The strongest correlation to flame performance is the run-up distance scaling factor. This trend was not observed with the liquid fuels. The reason for this is likely due to incomplete evaporation of the liquid fuel droplets resulting in a partially unburned mixture, effectively altering the intended equivalence ratio. Results suggest that the simple theory for run-up distance and flame acceleration must be modified to more accurately predict the behavior of gaseous fuels. Also, it is likely that more complex spray combustion modeling is required to accurately predict the flame behavior for liquid fuels.

Molecular Dynamics Simulations of Simple Liquids

ERIC Educational Resources Information Center

Speer, Owner F.; Wengerter, Brian C.; Taylor, Ramona S.

2004-01-01

An experiment, in which students were given the opportunity to perform molecular dynamics simulations on a series of molecular liquids using the Amber suite of programs, is presented. They were introduced to both physical theories underlying classical mechanics simulations and to the atom-atom pair distribution function.

Determination of para red, Sudan dyes, canthaxanthin, and astaxanthin in animal feeds using UPLC.

PubMed

Hou, Xiaolin; Li, Yonggang; Wu, Guojuan; Wang, Lei; Hong, Miao; Wu, Yongnin

2010-01-01

A simple high-performance liquid chromatography method was developed for quantitative determination of para red, Sudan I, Sudan II, Sudan III, Sudan IV, canthaxanthin, and astaxanthin in feedstuff. The sample was extracted using acetonitrile and cleaned up on a C(18) SPE column. The residues were analyzed using ultra-performance liquid chromatography coupled to a diode array detector at 500 nm. The mobile phase was acetonitrile-formic acid-water with a gradient elution condition. The external standard curves were calibrated. The mean recoveries of the seven colorants were 62.7-91.0% with relative standard deviation 2.6-10.4% (intra-day) and 4.0-13.2% (inter-day). The detection limits were in the range of 0.006-0.02 mg/kg.

A simple and green pathway toward nitrogen and sulfur dual doped hierarchically porous carbons from ionic liquids for oxygen reduction

NASA Astrophysics Data System (ADS)

Cui, Zhentao; Wang, Shuguang; Zhang, Yihe; Cao, Minhua

2014-08-01

We for the first time demonstrate a simple and green approach to heteroatom (N and S) co-doped hierarchically porous carbons (N-S-HC) with high surface area by using one organic ionic liquid as nitrogen, sulfur and carbon sources and the eutectic salt as templating. The resultant dual-doped N-S-HC catalysts exhibit significantly enhanced electrocatalytic activity, long-term operation stability, and tolerance to crossover effect compared to commercial Pt/C for oxygen reduction reactions (ORR) in alkaline environment. The excellent electrocatalytic performance may be attributed to the synergistic effects, which includes more catalytic sites for ORR provided by N-S heteroatom doping and high electron transfer rate provided by hierarchically porous structure. The DFT calculations reveal that the dual doping of S and N atoms lead to the redistribution of spin and charge densities, which may be responsible for the formation of a large number of carbon atom active sites. This newly developed approach may supply an efficient platform for the synthesis of a series of heteroatom doped carbon materials for fuel cells and other applications.

Application of hollow fiber-supported liquid-phase microextraction coupled with HPLC for the determination of guaifenesin enantiomer-protein binding.

PubMed

Hatami, Mehdi; Farhadi, Khalil

2012-07-01

A hollow fiber liquid-phase microextraction technique coupled with high-performance liquid chromatography with fluorescence detection was employed for determination and evaluation of the binding characteristics of drugs to bovine serum albumin (BSA). Enantiomers of guaifenesin (an expectorant drug) were investigated as a model system. After optimization of some influencing parameters on microextraction, the proposed method was used for calculation of the target drug distribution coefficient between n-octanol and the buffer solution as well as study of drug-BSA binding in physiological conditions. The developed method shows a new, improved and simple procedure for determination of free drug concentration in biological fluids and the extent of drug-protein binding. Copyright © 2011 John Wiley & Sons, Ltd.

Micro liquid chromatography-mass spectrometry with direct liquid introduction used for separation and quantitation of all-trans- and 13-cis-retinoic acids and their 4-oxo metabolites in human plasma.

PubMed

Ranalder, U B; Lausecker, B B; Huselton, C

1993-07-23

The separation and quantitation of the pentafluorobenzyl derivatives of all-trans- and 13-cis-retinoic acids and their 4-oxo metabolites in human plasma on micro high-performance liquid chromatographic columns (0.32 mm I.D.) is described. The column outlet was directly coupled to the source of a quadrupole mass spectrometer via a simple SFC-frit interface. Negative ion chemical ionization conditions were obtained by coaxial introduction of ammonia as a reagent gas. A signal-to-noise ratio well above 3 was obtained for 1 pg of each analyte injected. The limit of quantitation calculated from spiked biological plasma extracts was 0.3 ng/ml.

Binary Solvents Dispersive Liquid—Liquid Microextraction (BS-DLLME) Method for Determination of Tramadol in Urine Using High-Performance Liquid Chromatography

PubMed Central

2014-01-01

Background Tramadol is an opioid, synthetic analog of codeine and has been used for the treatment of acute or chronic pain may be abused. In this work, a developed Dispersive liquid liquid microextraction (DLLME) as binary solvents-based dispersive liquid-liquid microextraction (BS-DLLME) combined with high performance liquid chromatography (HPLC) with fluorescence detection (FD) was employed for determination of tramadol in the urine samples. This procedure involves the use of an appropriate mixture of binary extraction solvents (70 μL CHCl3 and 30 μL ethyl acetate) and disperser solvent (600 μL acetone) for the formation of cloudy solution in 5 ml urine sample comprising tramadol and NaCl (7.5%, w/v). After centrifuging, the small droplets of extraction solvents were precipitated. In the final step, the HPLC with fluorescence detection was used for determination of tramadol in the precipitated phase. Results Various factors on the efficiency of the proposed procedure were investigated and optimized. The detection limit (S/N = 3) and quantification limit (S/N = 10) were found 0.2 and 0.9 μg/L, respectively. The relative standard deviations (RSD) for the extraction of 30 μg L of tramadol was found 4.1% (n = 6). The relative recoveries of tramadol from urine samples at spiking levels of 10, 30 and 60 μg/L were in the range of 95.6 – 99.6%. Conclusions Compared with other methods, this method provides good figures of merit such as good repeatability, high extraction efficiency, short analysis time, simple procedure and can be used as microextraction technique for routine analysis in clinical laboratories. PMID:24495475

Determination of itopride in human plasma by liquid chromatography coupled to tandem mass spectrometric detection: application to a bioequivalence study.

PubMed

Lee, Heon-Woo; Seo, Ji-Hyung; Choi, Seung-Ki; Lee, Kyung-Tae

2007-01-30

A simple method using a one-step liquid-liquid extraction (LLE) with butyl acetate followed by high-performance liquid chromatography (HPLC) with positive ion electrospray ionization tandem mass spectrometric (ESI-MS/MS) detection was developed for the determination of itopride in human plasma, using sulpiride as an internal standard (IS). Acquisition was performed in multiple reaction monitoring (MRM) mode, by monitoring the transitions: m/z 359.5>166.1 for itopride and m/z 342.3>111.6 for IS, respectively. Analytes were chromatographed on an YMC C18 reverse-phase chromatographic column by isocratic elution with 1 mM ammonium acetate buffer-methanol (20: 80, v/v; pH 4.0 adjusted with acetic acid). Results were linear (r2=0.9999) over the studied range (0.5-1000 ng mL(-1)) with a total analysis time per run of 2 min for LC-MS/MS. The developed method was validated and successfully applied to bioequivalence studies of itopride hydrochloride in healthy male volunteers.

Optimization analysis of the motor cooling method in semi-closed single screw refrigeration compressor

NASA Astrophysics Data System (ADS)

Wang, Z. L.; Shen, Y. F.; Wang, Z. B.; Wang, J.

2017-08-01

Semi-closed single screw refrigeration compressors (SSRC) are widely used in refrigeration and air conditioning systems owing to the advantages of simple structure, balanced forces on the rotor, high volumetric efficiency and so on. In semi-closed SSRCs, motor is often cooled by suction gas or injected refrigerant liquid. Motor cooling method will changes the suction gas temperature, this to a certain extent, is an important factor influencing the thermal dynamic performance of a compressor. Thus the effects of motor cooling method on the performance of the compressor must be studied. In this paper mathematical models of motor cooling process by using these two methods were established. Influences of motor cooling parameters such as suction gas temperature, suction gas quantity, temperature of the injected refrigerant liquid and quantity of the injected refrigerant liquid on the thermal dynamic performance of the compressor were analyzed. The performances of the compressor using these two kinds of motor cooling methods were compared. The motor cooling capacity of the injected refrigerant liquid is proved to be better than the suction gas. All analysis results obtained can be useful for optimum design of the motor cooling process to improve the efficiency and the energy efficiency of the compressor.

Fingerprint chromatogram analysis of Pseudostellaria heterophylla (Miq.) Pax root by high performance liquid chromatography.

PubMed

Han, Chao; Chen, Junhui; Chen, Bo; Lee, Frank Sen-Chun; Wang, Xiaoru

2006-09-01

A simple and reliable high performance liquid chromatographic (HPLC) method has been developed and validated for the fingerprinting of extracts from the root of Pseudostellaria heterophylla (Miq.) Pax. HPLC with gradient elution was performed on an authentic reference standard of powdered P. heterophylla (Miq.) Pax root and 11 plant samples of the root were collected from different geographic locations. The HPLC chromatograms have been standardized through the selection and identification of reference peaks and the normalization of retention times and peak intensities of all the common peaks. The standardized HPLC fingerprints show high stability and reproducibility, and thus can be used effectively for the screening analysis or quality assessment of the root or its derived products. Similarity index calculations based on cosine angle values or correlation methods have been performed on the HPLC fingerprints. As a group, the fingerprints of the P. heterophylla (Miq.) Pax samples studied are highly correlated with closely similar fingerprints. Within the group, the samples can be further divided into subgroups based on hierarchical clustering analysis (HCA). Sample grouping based on HCA coincides nicely with those based on the geographical origins of the samples. The HPLC fingerprinting techniques thus have high potential in authentication or source-tracing types of applications.

A single step reversed-phase high performance liquid chromatography separation of polar and non-polar lipids.

PubMed

Olsson, Petter; Holmbäck, Jan; Herslöf, Bengt

2014-11-21

This paper reports a simple chromatographic system to separate lipids classes as well as their molecular species. By the use of phenyl coated silica as stationary phase in combination with a simple mobile phase consisting of methanol and water, all tested lipid classes elute within 30 min. Furthermore, a method to accurately predict retention times of specific lipid components for this type of chromatography is presented. Common detection systems were used, namely evaporative light scattering detection (ELSD), charged aerosol detection (CAD), electrospray mass spectrometry (ESI-MS), and UV detection. Copyright © 2014 Elsevier B.V. All rights reserved.

Automated dispersive liquid-liquid microextraction coupled to high performance liquid chromatography - cold vapour atomic fluorescence spectroscopy for the determination of mercury species in natural water samples.

PubMed

Liu, Yao-Min; Zhang, Feng-Ping; Jiao, Bao-Yu; Rao, Jin-Yu; Leng, Geng

2017-04-14

An automated, home-constructed, and low cost dispersive liquid-liquid microextraction (DLLME) device that directly coupled to a high performance liquid chromatography (HPLC) - cold vapour atomic fluorescence spectroscopy (CVAFS) system was designed and developed for the determination of trace concentrations of methylmercury (MeHg + ), ethylmercury (EtHg + ) and inorganic mercury (Hg 2+ ) in natural waters. With a simple, miniaturized and efficient automated DLLME system, nanogram amounts of these mercury species were extracted from natural water samples and injected into a hyphenated HPLC-CVAFS for quantification. The complete analytical procedure, including chelation, extraction, phase separation, collection and injection of the extracts, as well as HPLC-CVAFS quantification, was automated. Key parameters, such as the type and volume of the chelation, extraction and dispersive solvent, aspiration speed, sample pH, salt effect and matrix effect, were thoroughly investigated. Under the optimum conditions, linear range was 10-1200ngL -1 for EtHg + and 5-450ngL -1 for MeHg + and Hg 2+ . Limits of detection were 3.0ngL -1 for EtHg + and 1.5ngL -1 for MeHg + and Hg 2+ . Reproducibility and recoveries were assessed by spiking three natural water samples with different Hg concentrations, giving recoveries from 88.4-96.1%, and relative standard deviations <5.1%. Copyright © 2017 Elsevier B.V. All rights reserved.

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 limit of the film extraction technique for annular two-phase flow in a small tube

DOE Office of Scientific and Technical Information (OSTI.GOV)

Helm, D.E.; Lopez de Bertodano, M.; Beus, S.G.

1999-07-01

The limit of the liquid film extraction technique was identified in air-water and Freon-113 annular two-phase flow loops. The purpose of this research is to find the limit of the entrainment rate correlation obtained by Lopez de Bertodano et. al. (1998). The film extraction technique involves the suction of the liquid film through a porous tube and has been widely used to obtain annular flow entrainment and entrainment rate data. In these experiments there are two extraction probes. After the first extraction the entrained droplets in the gas core deposit on the tube wall. A new liquid film develops entirelymore » from liquid deposition and a second liquid film extraction is performed. While it is assumed that the entire liquid film is removed after the first extraction unit, this is not true for high liquid flow. At high liquid film flows the interfacial structure of the film becomes frothy. Then the entire liquid film cannot be removed at the first extraction unit, but continues on and is extracted at the second extraction unit. A simple model to characterize the limit of the extraction technique was obtained based on the hypothesis that the transition occurs due to a change in the wave structure. The resulting dimensionless correlation agrees with the data.« less

The limit of the film extraction technique for annular two-phase flow in a small tube

DOE Office of Scientific and Technical Information (OSTI.GOV)

Helm, D.E.; Lopez de Bertodano, M.; Beus, S.G.

1999-07-01

The limit of the liquid film extraction technique was identified in air-water and Freon-113 annular two-phase flow loops. The purpose of this research is to find the limit of the entrainment rate correlation obtained by Lopez de Bertodano et al. (1998). The film extraction technique involves the suction of the liquid film through a porous tube and has been widely used to obtain annular flow entrainment and entrainment rate data. In the experiments there are two extraction probes. After the first extraction the entrained droplets in the gas core deposit on the tube wall. A new liquid film develops entirelymore » from liquid deposition and a second liquid film extraction is performed. While it is assumed that the entire liquid film is removed after the first extraction unit, this is not true for high liquid flow. At high liquid film flows the interfacial structure of the film becomes frothy. Then the entire liquid film cannot be removed at the first extraction unit, but continues on and is extracted at the second extraction unit. A simple model to characterize the limit of the extraction technique was obtained based on the hypothesis that the transition occurs due to a change in the wave structure. The resulting dimensionless correlation agrees with the data.« less

Medicinal cannabis: Principal cannabinoids concentration and their stability evaluated by a high performance liquid chromatography coupled to diode array and quadrupole time of flight mass spectrometry method.

PubMed

Citti, Cinzia; Ciccarella, Giuseppe; Braghiroli, Daniela; Parenti, Carlo; Vandelli, Maria Angela; Cannazza, Giuseppe

2016-09-05

In the last few years, there has been a boost in the use of cannabis-based extracts for medicinal purposes, although their preparation procedure has not been standardized but rather decided by the individual pharmacists. The present work describes the development of a simple and rapid high performance liquid chromatography method with UV detection (HPLC-UV) for the qualitative and quantitative determination of the principal cannabinoids (CBD-A, CBD, CBN, THC and THC-A) that could be applied to all cannabis-based medicinal extracts (CMEs) and easily performed by a pharmacist. In order to evaluate the identity and purity of the analytes, a high-resolution mass spectrometry (HPLC-ESI-QTOF) analysis was also carried out. Full method validation has been performed in terms of specificity, selectivity, linearity, recovery, dilution integrity and thermal stability. Moreover, the influence of the solvent (ethyl alcohol and olive oil) was evaluated on cannabinoids degradation rate. An alternative extraction method has then been proposed in order to preserve cannabis monoterpene component in final CMEs. Copyright © 2016 Elsevier B.V. All rights reserved.

Cloud-point extraction and reversed-phase high-performance liquid chromatography for the determination of synthetic phenolic antioxidants in edible oils.

PubMed

Chen, Miao; Xia, Qinghai; Liu, Mousheng; Yang, Yaling

2011-01-01

A cloud-point extraction (CPE) method using Triton X-114 (TX-114) nonionic surfactant was developed for the extraction and preconcentration of propyl gallate (PG), tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) from edible oils. The optimum conditions of CPE were 2.5% (v/v) TX-114, 0.5% (w/v) NaCl and 40 min equilibration time at 50 °C. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography with ultraviolet detection at 280 nm, using a gradient mobile phase consisting of methanol and 1.5% (v/v) acetic acid. Under the studied conditions, 4 synthetic phenolic antioxidants (SPAs) were successfully separated within 24 min. The limits of detection (LOD) were 1.9 ng mL(-1) for PG, 11 ng mL(-1) for TBHQ, 2.3 ng mL(-1) for BHA, and 5.9 ng mL(-1) for BHT. Recoveries of the SPAs spiked into edible oil were in the range 81% to 88%. The CPE method was shown to be potentially useful for the preconcentration of the target analytes, with a preconcentration factor of 14. Moreover, the method is simple, has high sensitivity, consumes much less solvent than traditional methods, and is environment-friendly. Practical Application: The method established in this article uses less organic solvent to extract SPAs from edible oils; it is simple, highly sensitive and results in no pollution to the environment.

Pharmacokinetics and tissue distribution study of Praeruptorin D from Radix peucedani in rats by high-performance liquid chromatography (HPLC).

PubMed

Liang, Taigang; Yue, Wenyan; Du, Xue; Ren, Luhui; Li, Qingshan

2012-01-01

Praeruptorin D (PD), a major pyranocoumarin isolated from Radix Peucedani, exhibited antitumor and anti-inflammatory activities. The aim of this study was to investigate the pharmacokinetics and tissue distribution of PD in rats following intravenous (i.v.) administration. The levels of PD in plasma and tissues were measured by a simple and sensitive reversed-phase high-performance liquid chromatography (HPLC) method. The biosamples were treated by liquid-liquid extraction (LLE) with methyl tert-butyl ether (MTBE) and osthole was used as the internal standard (IS). The chromatographic separation was accomplished on a reversed-phase C(18) column using methanol-water (75:25, v/v) as mobile phase at a flow rate of 0.8 mL/min and ultraviolet detection wave length was set at 323 nm. The results demonstrate that this method has excellent specificity, linearity, precision, accuracy and recovery. The pharmacokinetic study found that PD fitted well into a two-compartment model with a fast distribution phase and a relative slow elimination phase. Tissue distribution showed that the highest concentration was observed in the lung, followed by heart, liver and kidney. Furthermore, PD can also be detected in the brain, which indicated that PD could cross the blood-brain barrier after i.v. administration.

Constant pressure mode extended simple gradient liquid chromatography system for micro and nanocolumns.

PubMed

Šesták, Jozef; Kahle, Vladislav

2014-07-11

Performing gradient liquid chromatography at constant pressure instead of constant flow rate has serious potential for shortening the analysis time and increasing the productivity of HPLC instruments that use gradient methods. However, in the constant pressure mode the decreasing column permeability during a long period of time negatively affects the repeatability of retention time. Thus a volume-based approach, in which the detector signal is plotted as a function of retention volume, must be taken into consideration. Traditional HPLC equipment, however, requires quite complex hardware and software modifications in order to work at constant pressure and in the volume-based mode. In this short communication, a low cost and easily feasible pressure-controlled extension of the previously described simple gradient liquid chromatography platform is proposed. A test mixture of four nitro esters was separated by 10-60% (v/v) acetone/water gradient and a high repeatability of retention volumes at 20MPa (RSD less than 0.45%) was realized. Separations were also performed at different values of pressure (20, 25, and 31MPa), and only small variations of the retention volumes (up to 0.8%) were observed. In this particular case, the gain in the analysis speed of 7% compared to the constant flow mode was realized at a constant pressure. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of triazine herbicides in fresh vegetables by dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction high performance liquid chromatography.

PubMed

Wu, Lijie; Hu, Mingzhu; Li, Zhanchao; Song, Ying; Yu, Cui; Zhang, Yupu; Zhang, Hanqi; Yu, Aimin; Ma, Qiang; Wang, Ziming

2015-02-01

A novel extraction method, dynamic microwave-assisted extraction coupled with homogeneous ionic liquid microextraction, was developed for the determination of triazine herbicides, including desmetryn, terbumeton, propazine, terbuthylazine, dimethametryn, and dipropetryn in fresh vegetable samples by high performance liquid chromatography (HPLC). In the developed method, 120 μL of 1-butyl-3-methylimidazolium tetrafluoroborate ([C4MIM][BF4]) was added to 10 mL of aqueous solution containing 0.3 g of NaCl to obtained the extraction solvent. Six triazines could be extracted completely within 4 min by the present method. Then, [NH4][PF6] was added into the extract to form a water-insoluble ionic liquid [C4MIM][PF6] via a simple metathesis reaction, and the analytes were enriched into the ionic liquid phase. After centrifugation and dilution with acetonitrile, the resulting solution was analyzed directly by HPLC. The effects of some experimental parameters, including type and volume of ionic liquid, volume of extraction solvent, amount of ion-pairing agent [NH4][PF6], salt concentration, microwave power, and flow rate of extraction solvent on the extraction efficiency were investigated and optimized. Under the optimum experimental conditions, the linearity for determining the analytes was in the range of 2.50-250.00 μg kg(-1), with the correlation coefficients ranging from 0.9989 to 0.9999. When the present method was applied to the analysis of vegetable samples, satisfactory recoveries were obtained in the range of 76.8%-106.9%, and relative standard deviations were lower than 9.8%.

Ionic Liquid Activation of Amorphous Metal-Oxide Semiconductors for Flexible Transparent Electronic Devices

DOE PAGES

Pudasaini, Pushpa Raj; Noh, Joo Hyon; Wong, Anthony T.; ...

2016-02-09

To begin this abstract, amorphous metal-oxide semiconductors offer the high carrier mobilities and excellent large-area uniformity required for high performance, transparent, flexible electronic devices; however, a critical bottleneck to their widespread implementation is the need to activate these materials at high temperatures which are not compatible with flexible polymer substrates. The highly controllable activation of amorphous indium gallium zinc oxide semiconductor channels using ionic liquid gating at room temperature is reported. Activation is controlled by electric field-induced oxygen migration across the ionic liquid-semiconductor interface. In addition to activation of unannealed devices, it is shown that threshold voltages of a transistormore » can be linearly tuned between the enhancement and depletion modes. Finally, the first ever example of transparent flexible thin film metal oxide transistor on a polyamide substrate created using this simple technique is demonstrated. Finally, this study demonstrates the potential of field-induced activation as a promising alternative to traditional postdeposition thermal annealing which opens the door to wide scale implementation into flexible electronic applications.« less

Surface nanodroplets for highly efficient liquid-liquid microextraction

NASA Astrophysics Data System (ADS)

Li, Miaosi; Lu, Ziyang; Yu, Haitao; Zhang, Xuehua

2016-11-01

Nanoscale droplets on a substrate are an essential element for a wide range of applications, such as laboratory-on-chip devices, simple and highly efficient miniaturized reactors for concentrating products, high-throughput single-bacteria or single-biomolecular analysis, encapsulation, and high-resolution imaging techniques. The solvent exchange process is a simple bottom-up approach for producing droplets at solid-liquid interfaces that are only several tens to hundreds of nanometers in height, or a few femtoliters in volume Oil nanodroplets can be produced on a substrate by solvent exchange in which a good solvent of oil is displaced by a poor solvent. Our previous work has significantly advanced understanding of the principle of solvent exchange, and the droplet size can be well-controlled by several parameters, including flow rates, flow geometry, gravitational effect and composition of solutions. In this work, we studied the microextraction effect of surface nanodroplets. Oil nanodroplets have been demonstrated to provide highly-efficient liquid-liquid microextraction of hydrophobic solute in a highly diluted solution. This effect proved the feasibility of nanodroplets as a platform for preconcentrating compounds for in situ highly sensitive microanalysis without further separation. Also the long lifetime and temporal stability of surface nanodroplets allow for some long-term extraction process and extraction without addition of stabilisers.

High conversion efficiency distributed feedback laser from a dye-doped holographic transmission grating

NASA Astrophysics Data System (ADS)

Liu, Lijuan; Zhang, Guiyang; Kong, Xiaobo; Liu, Yonggang; Xuan, Li

2018-01-01

A high conversion efficiency distributed feedback (DFB) laser from a dye-doped holographic polymer dispersed liquid crystal (HPDLC) transmission grating structure was reported. The alignment polyimide (PI) films were used to control the orientation of the phase separated liquid crystals (LCs) to increase the refractive index difference between the LC and the polymer, so it can provide better light feedback. The lasing wavelength located at 645.8 nm near the maximum of the amplified spontaneous emission (ASE) spectrum with the lowest threshold 0.97 μ J/pulse and the highest conversion efficiency 1.6% was obtained. The laser performance under electric field were also investigated and illustrated. The simple configuration, one-step fabrication organic dye laser shows the potential to realize ultra-low cost plastic lasers.

Highly crumpled solar reduced graphene oxide electrode for supercapacitor application

NASA Astrophysics Data System (ADS)

Mohanapriya, K.; Ahirrao, Dinesh J.; Jha, Neetu

2018-04-01

Highly crumpled solar reduced graphene oxide (CSRGO) was synthesized by simple and rapid method through freezing the solar reduced graphene oxide aqueous suspension using liquid nitrogen and used as electrode material for supercapacitor application. This electrode material was characterized by transmission electron microscope (TEM), X-Ray diffractometer (XRD) and Raman Spectroscopy techniques to understand the morphology and structure. The electrochemical performance was studied by cyclic voltammetry (CV), galvanostatic charge/discharge (CD) and electrochemical impedance spectroscopy (EIS) using 6M KOH electrolyte. The CSRGO exhibit high specifc capacitance of 210.1 F g-1 at the current density of 0.5 A g-1 and shows excellent rate capability. These features make the CSRGO material as promising electrode for high-performance supercapacitors.

Simultaneous determination of seven phthalic acid esters in beverages using ultrasound and vortex-assisted dispersive liquid-liquid microextraction followed by high-performance liquid chromatography.

PubMed

Yılmaz, Pelin Köseoğlu; Ertaş, Abdulselam; Kolak, Ufuk

2014-08-01

A sensitive, rapid, and simple high-performance liquid chromatography with UV detection method was developed for the simultaneous determination of seven phthalic acid esters (dimethyl phthalate, dipropyl phthalate, di-n-butyl phthalate, benzyl butyl phthalate, dicyclohexyl phthalate, di-(2-ethylhexyl) phthalate, and di-n-octyl phthalate) in several kinds of beverage samples. Ultrasound and vortex-assisted dispersive liquid-liquid microextraction method was used. The separation was performed using an Intersil ODS-3 column (C18 , 250 × 4.6 mm, 5.0 μm) and a gradient elution with a mobile phase consisting of MeOH/ACN (50:50) and 0.2 M KH2 PO4 buffer. Analytes were detected by a UV detector at 230 nm. The developed method was validated in terms of linearity, limit of detection, limit of quantification, repeatability, accuracy, and recovery. Calibration equations and correlation coefficients (> 0.99) were calculated by least squares method with weighting factor. The limit of detection and quantification were in the range of 0.019-0.208 and 0.072-0.483 μg/L. The repeatability and intermediate precision were determined in terms of relative standard deviation to be within 0.03-3.93 and 0.02-4.74%, respectively. The accuracy was found to be in the range of -14.55 to 15.57% in terms of relative error. Seventeen different beverage samples in plastic bottles were successfully analyzed, and ten of them were found to be contaminated by different phthalic acid esters. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of working fluids on thermal performance of closed loop pulsating heat pipe

NASA Astrophysics Data System (ADS)

Kolková, Zuzana; Malcho, Milan

2014-08-01

Improving the performance of electrical components needs higher heat removal from these systems. One of the solutions available is to use a sealed heat pipe with a throbbing filling, where development meets the current requirements for intensification of heat removal and elimination of moving parts cooling systems. Heat pipes operate using phase change working fluid, and it is evaporation and condensation. They have a meandering shape and are characterized by high intensity of heat transfer, high durability and reliability. Advantage of these tubes is that it is not necessary to create the internal capillary structure for transporting liquid and they need any pump to the working fluid circulation. They have a simple structure, low cost, high performance, and they can be used for various structural applications. The choice of working fluid volume and performance affects thermal performance. Distilled water, ethanol and acetone were used in the performance ranges 0-80%.

Methanesulfonic acid-assisted synthesis of N/S co-doped hierarchically porous carbon for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Huo, Silu; Liu, Mingquan; Wu, Linlin; Liu, Mingjie; Xu, Min; Ni, Wei; Yan, Yi-Ming

2018-05-01

Nitrogen and sulfur co-doped carbons are considered as electrode materials for high performance supercapacitors, while their further development is still limited by complicated synthesis procedure, unsatisfied structure and low energy density. Developing a simple synthetic strategy to obtain rationally structured carbon materials and high supercapacitor performance is remaining a grand challenge. Herein, we describe the synthesis of nitrogen and sulfur co-doped hierarchical porous carbons as high performance supercapacitors electrode by a methanesulfonic acid-assisted one-step carbonization and activation of the freeze-dried precursors mixture. The as-prepared carbon material not only exhibits ideally hierarchical pores, but also realizes uniform nitrogen and sulfur co-doping. In 6.0 M KOH electrolyte, the material can achieve a high specific capacitance of 272 F g-1 at 1.0 A g-1 and a promising rate performance retaining 172 F g-1 even at 100 A g-1. Moreover, a fabricated symmetric supercapacitor based on as-prepared nitrogen and sulfur co-doped hierarchical porous carbon delivers high energy densities of 12.4 W h kg-1 and 8.0 W h kg-1 in 6.0 M KOH liquid and KOH/PVA solid-state electrolytes, respectively. This work presents a simple and effective methanesulfonic acid-assisted approach for mass production of heteroatomic doping hierarchical porous carbons for future energy storage applications.

Self-diffusion and microscopic dynamics in a gold-silicon liquid investigated with quasielastic neutron scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evenson, Zach, E-mail: Zachary.Evenson@frm2.tum.de; Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt; Yang, Fan

2016-03-21

We use incoherent quasielastic neutron scattering to study the atomic dynamics of gold in a eutectic Au{sub 81}Si{sub 19} melt. Despite the glass-forming nature of this system, the gold self-diffusivity displays an Arrhenius behavior with a low activation energy characteristic of simple liquids. At high temperatures, long-range transport of gold atoms is well described by hydrodynamic theory with a simple exponential decay of the self-correlation function. On cooling towards the melting temperature, structural relaxation crosses over to a highly stretched exponential behavior. This suggests the onset of a heterogeneous dynamics, even in the equilibrium melt, and is indicative of amore » very fragile liquid.« less

Facile synthesis of poly(ionic liquid)-bonded magnetic nanospheres as a high-performance sorbent for the pretreatment and determination of phenolic compounds in water samples.

PubMed

Bi, Wentao; Wang, Man; Yang, Xiaodi; Row, Kyung Ho

2014-07-01

Poly(ionic liquid)-bonded magnetic nanospheres were easily synthesized and applied to the pretreatment and determination of phenolic compounds in water samples, which have detrimental effects on water quality and the health of living beings. The high affinity of poly(ionic liquid)s toward the target compounds as well as the magnetic behavior of Fe3 O4 were combined in this material to provide an efficient and simple magnetic solid-phase extraction approach. The adsorption behavior of the poly(ionic liquid)-bonded magnetic nanospheres was examined to optimize the synthesis. Different parameters affecting the magnetic solid-phase extraction of phenolic compounds were assessed in terms of adsorption and recovery. Under the optimal conditions, the proposed method showed excellent detection sensitivity with limits of detection in the range of 0.3-0.8 ng/mL and precision in the range of 1.2-3.3%. This method was also applied successfully to the analysis of real water samples; good spiked recoveries over the range of 82.5-99.2% were obtained. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Non-allowed Pharmacologically Active Substances in Physical and Sexual Performance Enhancing Products

PubMed Central

Pellegrini, Manuela; Rotolo, Maria Concetta; Busardò, Francesco Paolo; Pacifici, Roberta; Pichini, Simona

2017-01-01

Background: Recently, a large amount of physical and sexual performance enhancing products have started to be freely sold mainly on internet web sites as dietary supplements. However, there a high suspicion that pharmacologically active substance, prohibited in these products, can be present to provide the expected effect. Methods: A simple and rapid systematic toxicological analysis by gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry has been applied after a liquid-liquid extraction at acidic, neutral and alkaline pH with chloroform-isopropanol (9:1 v/v). The assays were validated in the range from 10 mg to 250 mg/g products showing a good linearity for the calibration curves (r2 ≥0.99). Mean extraction recoveries of analytes from different products were always higher than 90% and intra-assay and inter-assay precision and accuracy were always better than 15%. Results: The developed method was applied to the analysis of products with a high percentage of sales in websites and smart and sexy shops. In twelve of eighty supplements, anabolic steroids, anti-estrogenic drugs, psychoactive substances and sildenafil and analogs were identified and quantified. Conclusion: Eventual health hazards caused by the hidden presence of pharmacologically active substances in physical and sexual performance enhancing products are reported. PMID:27799033

Measuring Drag Force in Newtonian Liquids

NASA Astrophysics Data System (ADS)

Mawhinney, Matthew T.; O'Donnell, Mary Kate; Fingerut, Jonathan; Habdas, Piotr

2012-03-01

The experiments described in this paper have two goals. The first goal is to show how students can perform simple but fundamental measurements of objects moving through simple liquids (such as water, oil, or honey). In doing so, students can verify Stokes' law, which governs the motion of spheres through simple liquids, and see how it fails at higher object speeds. Moreover, they can qualitatively study fluid patterns at various object speeds (Reynolds numbers). The second goal is to help students make connections between physics and other sciences. Specifically, the results of these experiments can be used to help students understand the role of fluid motion in determining the shape of an organism, or where it lives. At Saint Josephs University we have developed these experiments as part of a newly developed course in biomechanics where both physics and biology undergraduate students bring their ideas and expertise to enrich a shared learning environment.

A rapid and simple pretreatment method for benzoylurea insecticides in honey samples using in-syringe dispersive liquid-liquid microextraction based on the direct solidification of ionic liquids.

PubMed

Wang, Huazi; Hu, Lu; Li, Wanzhen; Lu, Runhua; Zhang, Sanbing; Zhou, Wenfeng; Gao, Haixiang

2016-11-04

A pretreatment method using in-syringe dispersive liquid-liquid microextraction based on the direct solidification of ionic liquids before high performance liquid chromatography analysis was developed for the determination of benzoylurea insecticides (BUs) in honey samples. The hydrophobic ionic liquid [N 4444 ][PF 6 ], formed in situ by the hydrophilic ionic liquid [N 4444 ]Cl and the ion exchange reagent KPF 6 , was used to extract the target analytes. The entire extraction procedure was performed in a syringe. The extractant was solidified at room temperature and collected using a nylon membrane filter. This technique did not require a dispersive solvent, vortex mixer, ultrasound bath, or centrifugation. The parameters affecting the extraction efficiency were investigated through an experimental design. Under the optimal conditions, the limits of detection for the four BUs varied from 0.21 to 0.42μgL -1 in solution (2.1-4.2μgkg -1 in honey). Good linearities were obtained in the range of 2-300μgL -1 , with coefficients of determination greater than 0.999. The recoveries of the four BUs ranged from 80.94% to 84.59%. The intra-day (n=3) and inter-day (n=3) relative standard deviations were less than 5.08%. Finally, the proposed method was applied to the determination of BUs in commercial honey samples with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica

PubMed Central

Naveen, P.; Lingaraju, H. B.; Prasad, K. Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica, is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica. RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography–mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica. SUMMARY The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica. The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica. Abbreviations Used: M. indica: Mangifera indica, RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification. PMID:28539748

Rapid Development and Validation of Improved Reversed-Phase High-performance Liquid Chromatography Method for the Quantification of Mangiferin, a Polyphenol Xanthone Glycoside in Mangifera indica.

PubMed

Naveen, P; Lingaraju, H B; Prasad, K Shyam

2017-01-01

Mangiferin, a polyphenolic xanthone glycoside from Mangifera indica , is used as traditional medicine for the treatment of numerous diseases. The present study was aimed to develop and validate a reversed-phase high-performance liquid chromatography (RP-HPLC) method for the quantification of mangiferin from the bark extract of M. indica . RP-HPLC analysis was performed by isocratic elution with a low-pressure gradient using 0.1% formic acid: acetonitrile (87:13) as a mobile phase with a flow rate of 1.5 ml/min. The separation was done at 26°C using a Kinetex XB-C18 column as stationary phase and the detection wavelength at 256 nm. The proposed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification, and robustness by the International Conference on Harmonisation guidelines. In linearity, the excellent correlation coefficient more than 0.999 indicated good fitting of the curve and also good linearity. The intra- and inter-day precision showed < 1% of relative standard deviation of peak area indicated high reliability and reproducibility of the method. The recovery values at three different levels (50%, 100%, and 150%) of spiked samples were found to be 100.47, 100.89, and 100.99, respectively, and low standard deviation value < 1% shows high accuracy of the method. In robustness, the results remain unaffected by small variation in the analytical parameters, which shows the robustness of the method. Liquid chromatography-mass spectrometry analysis confirmed the presence of mangiferin with M/Z value of 421. The assay developed by HPLC method is a simple, rapid, and reliable for the determination of mangiferin from M. indica . The present study was intended to develop and validate an RP-HPLC method for the quantification of mangiferin from the bark extract of M. indica . The developed method was validated for linearity, precision, accuracy, limit of detection, limit of quantification and robustness by International Conference on Harmonization guidelines. This study proved that the developed assay by HPLC method is a simple, rapid and reliable for the quantification of the mangiferin from M. indica . Abbreviations Used: M. indica : Mangifera indica , RP-HPLC: Reversed-phase high-performance liquid chromatography, M/Z: Mass to charge ratio, ICH: International conference on harmonization, % RSD: Percentage of relative standard deviation, ppm: Parts per million, LOD: Limit of detection, LOQ: Limit of quantification.

Simultaneous determination of atorvastatin and valsartan in human plasma by solid-based disperser liquid-liquid microextraction followed by high-performance liquid chromatography-diode array detection.

PubMed

Farajzadeh, Mir Ali; Khorram, Parisa; Pazhohan, Azar

2016-04-01

A simple, sensitive, and efficient method has been developed for simultaneous estimation of valsartan and atorvastatin in human plasma by combination of solid-based dispersive liquid-liquid microextraction and high performance liquid chromatography-diode array detection. In the proposed method, 1,2-dibromoethane (extraction solvent) is added on a sugar cube (as a solid disperser) and it is introduced into plasma sample containing the analytes. After manual shaking and centrifugation, the resultant sedimented phase is subjected to back extraction into a small volume of sodium hydrogen carbonate solution using air-assisted liquid-liquid microextraction. Then the cloudy solution is centrifuged and the obtained aqueous phase is transferred into a microtube and analyzed by the separation system. Under the optimal conditions, extraction recoveries are obtained in the range of 81-90%. Calibration curves plotted in drug-free plasma sample are linear in the ranges of 5-5000μgL(-1) for valsartan and 10-5000μgL(-1) for atorvastatin with the coefficients of determination higher than 0.997. Limits of detection and quantification of the studied analytes in plasma sample are 0.30-2.6 and 1.0-8.2μgL(-1), respectively. Intra-day (n=6) and inter-days (n=4) precisions of the method are satisfactory with relative standard deviations less than 7.4% (at three levels of 10, 500, and 2000μgL(-1), each analyte). These data suggest that the method can be successfully applied to determine trace amounts of valsartan and atorvastatin in human plasma samples. Copyright © 2016 Elsevier B.V. All rights reserved.

In situ derivatization-ultrasound-assisted dispersive liquid-liquid microextraction for the determination of neurotransmitters in Parkinson's rat brain microdialysates by ultra high performance liquid chromatography-tandem mass spectrometry.

PubMed

He, Yongrui; Zhao, Xian-En; Zhu, Shuyun; Wei, Na; Sun, Jing; Zhou, Yubi; Liu, Shu; Liu, Zhiqiang; Chen, Guang; Suo, Yourui; You, Jinmao

2016-08-05

Simultaneous monitoring of several neurotransmitters (NTs) linked to Parkinson's disease (PD) has important scientific significance for PD related pathology, pharmacology and drug screening. A new simple, fast and sensitive analytical method, based on in situ derivatization-ultrasound-assisted dispersive liquid-liquid microextraction (in situ DUADLLME) in a single step, has been proposed for the quantitative determination of catecholamines and their biosynthesis precursors and metabolites in rat brain microdialysates. The method involved the rapid injection of the mixture of low toxic bromobenzene (extractant) and acetonitrile (dispersant), which containing commercial Lissamine rhodamine B sulfonyl chloride (LRSC) as derivatization reagent, into the aqueous phase of sample and buffer, and the following in situ DUADLLME procedure. After centrifugation, 50μL of the sedimented phase (bromobenzene) was directly injected for ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) detection in multiple reaction monitoring (MRM) mode. This interesting combination brought the advantages of speediness, simpleness, low matrix effects and high sensitivity in an effective way. Parameters of in situ DUADLLME and UHPLC-MS/MS conditions were all optimized in detail. The optimum conditions of in situ DUADLLME were found to be 30μL of microdialysates, 150μL of acetonitrile containing LRSC, 50μL of bromobenzene and 800μL of NaHCO3-Na2CO3 buffer (pH 10.5) for 3.0min at 37°C. Under the optimized conditions, good linearity was observed with LODs (S/N>3) and LOQs (S/N>10) of LRSC derivatized-NTs in the range of 0.002-0.004 and 0.007-0.015 nmol/L, respectively. It also brought good precision (3.2-12.8%, peak area CVs%), accuracy (94.2-108.6%), recovery (94.5-105.5%) and stability (3.8-8.1%, peak area CVs%) results. Moreover, LRSC derivatization significantly improved chromatographic resolution and MS detection sensitivity of NTs when compared with the reported studies through the introduction of a permanent charged moiety from LRSC into NTs. Taken together, this in situ DUADLLME method was successfully applied for the simultaneous determination of six NTs in biological samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Optimisation of solid-phase microextraction coupled to HPLC-UV for the determination of organochlorine pesticides and their metabolites in environmental liquid samples.

PubMed

Torres Padrón, M E; Sosa Ferrera, Z; Santana Rodríguez, J J

2006-09-01

A solid-phase microextraction (SPME) procedure using two commercial fibers coupled with high-performance liquid chromatography (HPLC) is presented for the extraction and determination of organochlorine pesticides in water samples. We have evaluated the extraction efficiency of this kind of compound using two different fibers: 60-mum polydimethylsiloxane-divinylbenzene (PDMS-DVB) and Carbowax/TPR-100 (CW/TPR). Parameters involved in the extraction and desorption procedures (e.g. extraction time, ionic strength, extraction temperature, desorption and soaking time) were studied and optimized to achieve the maximum efficiency. Results indicate that both PDMS-DVB and CW/TPR fibers are suitable for the extraction of this type of compound, and a simple calibration curve method based on simple aqueous standards can be used. All the correlation coefficients were better than 0.9950, and the RSDs ranged from 7% to 13% for 60-mum PDMS-DVB fiber and from 3% to 10% for CW/TPR fiber. Optimized procedures were applied to the determination of a mixture of six organochlorine pesticides in environmental liquid samples (sea, sewage and ground waters), employing HPLC with UV-diode array detector.

Advanced characterization of electrowetting retroreflectors.

PubMed

Kilaru, Murali K; Yang, Jia; Heikenfeld, Jason

2009-09-28

Electrowetting retroreflectors use a simple and scalable construction, and incorporate an electrically tunable liquid lenslet. By electrically modulating the lenslet geometry, the reflection is switched between retroreflection and scattering. In this paper, we report new capability and characterization, including higher index liquids and contrast ratio as a function of contact angle (theta(V)). The reflected intensity is also spatially profiled and reported as a function of view angle. A high contrast ratio of >16X is demonstrated, and methods for further improving performance are discussed. Because the electrowetting retroreflector platform is broad spectrum (VIS-IR), the electrowetting retroreflector may be useful for a large variety of naked eye applications such as safety markings, road-signage, or friend-foe-identification.

Morphology controlled synthesis of platinum nanoparticles performed on the surface of graphene oxide using a gas-liquid interfacial reaction and its application for high-performance electrochemical sensing.

PubMed

Bai, Wushuang; Sheng, Qinglin; Zheng, Jianbin

2016-07-21

In this paper, we report a novel morphology-controlled synthetic method. Platinum (Pt) nanoparticles with three kinds of morphology (aggregation-like, cube-like and globular) were grown on the surface of graphene oxide (GO) using a simple gas-liquid interfacial reaction and Pt/GO nanocomposites were obtained successfully. According to the experimental results, the morphology of the Pt nanoparticles can be controlled by adjusting the reaction temperature with the protection of chitosan. The obtained Pt/GO nanocomposites were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and fourier transform infrared spectroscopy (FTIR). Then the Pt/GO nanocomposites with the three kinds of morphology were all used to fabricate electrochemical sensors. The electrochemical experimental results indicated that compared with various reported electrochemical sensors, the Pt/GO modified sensors in this work exhibit a low detection limit, high sensitivity and an extra wide linear range for the detection of nitrite. In addition, the synthesis of Pt particles based on a gas-liquid interfacial reaction provides a new platform for the controllable synthesis of nanomaterials.

Determination of metabolite of nicergoline in human plasma by high-performance liquid chromatography and its application in pharmacokinetic studies

PubMed Central

Zheng, Rong; Wu, Yi-Hong; Jiang, De-Xi; Zhang, Dan

2012-01-01

A fast, simple and sensitive high performance liquid chromatographic (HPLC) method has been developed for determination of 10α-methoxy-6-methyl ergoline-8β-methanol (MDL, a main metabolite of nicergoline) in human plasma. One-step liquid–liquid extraction (LLE) with diethyl ether was employed as the sample preparation method. Tizanidine hydrochloride was selected as the internal standard (IS). Analysis was carried out on a Diamonsil ODS column (150 mm×4.6 mm, 5 μm) using acetonitrile–ammonium acetate (0.1 mol/L) (15/85, v/v) as mobile phase at detection wavelength of 224 nm. The calibration curves were linear over the range of 2.288–73.2 ng/mL with a lower limit of quantitation (LLOQ) of 2.288 ng/mL. The intra- and inter-day precision values were below 13% and the recoveries were from 74.47% to 83.20% at three quality control levels. The method herein described was successfully applied in a randomized crossover bioequivalence study of two different nicergoline preparations after administration of 30 mg in 20 healthy volunteers. PMID:29403722

Determination of efavirenz in human dried blood spots by reversed-phase high-performance liquid chromatography with UV detection.

PubMed

Hoffman, Justin T; Rossi, Steven S; Espina-Quinto, Rowena; Letendre, Scott; Capparelli, Edmund V

2013-04-01

Previously published methods for determination of efavirenz (EFV) in human dried blood spots (DBS) use costly and complex liquid chromatography/mass spectrometry. We describe the validation and evaluation of a simple and inexpensive high-performance liquid chromatography method for EFV quantification in human DBS and dried plasma spots (DPS), using ultraviolet detection appropriate for resource-limited settings. One hundred microliters of heparinized whole blood or plasma were spotted onto blood collection cards, dried, punched, and eluted. Eluates are injected onto a C-18 reversed phase high-performance liquid chromatography column. EFV is separated isocratically using a potassium phosphate and acetonitrile mobile phase. Ultraviolet detection is at 245 nm. Quantitation is by use of external calibration standards. Following validation, the method was evaluated using whole blood and plasma from HIV-positive patients undergoing EFV therapy. Mean recovery of drug from DBS is 91.5%. The method is linear over the validated concentration range of 0.3125-20.0 μg/mL. A good correlation (Spearman r = 0.96) between paired plasma and DBS EFV concentrations from the clinical samples was observed, and hematocrit level was not found to be a significant determinant of the EFV DBS level. The mean observed C DBS/C plasma ratio was 0.68. A good correlation (Spearman r = 0.96) between paired plasma and DPS EFV concentrations from the clinical samples was observed. The mean percent deviation of DPS samples from plasma samples is 1.68%. Dried whole blood spot or dried plasma spot sampling is well suited for monitoring EFV therapy in resource-limited settings, particularly when high sensitivity is not essential.

NASA Flexible Screen Propellant Management Device (PMD) Demonstration With Cryogenic Liquid

NASA Technical Reports Server (NTRS)

Wollen, Mark; Bakke, Victor; Baker, James

2012-01-01

While evaluating various options for liquid methane and liquid oxygen propellant management for lunar missions, Innovative Engineering Solutions (IES) conceived the flexible screen device as a potential simple alternative to conventional propellant management devices (PMD). An apparatus was designed and fabricated to test flexible screen devices in liquid nitrogen. After resolution of a number of issues (discussed in detail in the paper), a fine mesh screen (325 by 2300 wires per inch) spring return assembly was successfully tested. No significant degradation in the screen bubble point was observed either due to the screen stretching process or due to cyclic fatigue during testing. An estimated 30 to 50 deflection cycles, and approximately 3 to 5 thermal cycles, were performed on the final screen specimen, prior to and between formally recorded testing. These cycles included some "abusive" pressure cycling, where gas or liquid was driven through the screen at rates that produced differential pressures across the screen of several times the bubble point pressure. No obvious performance degradation or other changes were observed over the duration of testing. In summary, it is felt by the author that these simple tests validated the feasibility of the flexible screen PMD concept for use with cryogenic propellants.

Oscillating Droplets and Incompressible Liquids: Slow-Motion Visualization of Experiments with Fluids

ERIC Educational Resources Information Center

Vollmer, Michael; Mollmann, Klaus-Peter

2012-01-01

We present fascinating simple demonstration experiments recorded with high-speed cameras in the field of fluid dynamics. Examples include oscillations of falling droplets, effects happening upon impact of a liquid droplet into a liquid, the disintegration of extremely large droplets in free fall and the consequences of incompressibility. (Contains…

A new ether-based electrolyte for dendrite-free lithium-metal based rechargeable batteries

PubMed Central

Miao, Rongrong; Yang, Jun; Xu, Zhixin; Wang, Jiulin; Nuli, Yanna; Sun, Limin

2016-01-01

A new ether-based electrolyte to match lithium metal electrode is prepared by introducing 1, 4-dioxane as co-solvent into lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane solution. Under the synergetic effect of solvents and salt, this simple liquid electrolyte presents stable Li cycling with dendrite-free Li deposition even at relatively high current rate, high coulombic efficiency of ca. 98%, and good anodic stability up to ~4.87 V vs Li RE. Its excellent performance will open up a new possibility for high energy-density rechargeable Li metal battery system. PMID:26878890

Applications using high-Tc superconducting terahertz emitters

PubMed Central

Nakade, Kurama; Kashiwagi, Takanari; Saiwai, Yoshihiko; Minami, Hidetoshi; Yamamoto, Takashi; Klemm, Richard A.; Kadowaki, Kazuo

2016-01-01

Using recently-developed THz emitters constructed from single crystals of the high-Tc superconductor Bi2Sr2CaCu2O8+δ, we performed three prototype tests of the devices to demonstrate their unique characteristic properties for various practical applications. The first is a compact and simple transmission type of THz imaging system using a Stirling cryocooler. The second is a high-resolution Michelson interferometer used as a phase-sensitive reflection-type imaging system. The third is a system with precise temperature control to measure the liquid absorption coefficient. The detailed characteristics of these systems are discussed. PMID:26983905

High pressure gas spheres for neutron and photon experiments

NASA Astrophysics Data System (ADS)

Rupp, G.; Petrich, D.; Käppeler, F.; Kaltenbaek, J.; Leugers, B.; Reifarth, R.

2009-09-01

High pressure gas spheres have been designed and successfully used in several nuclear physics experiments on noble gases. The pros and cons of this solution are the simple design and the high reliability versus the fact that the density is limited to 40-60% of liquid or solid gas samples. Originally produced for neutron capture studies at keV energies, the comparably small mass of the gas spheres were an important advantage, which turned out to be of relevance for other applications as well. The construction, performance, and operation of the spheres are described and examples for their use are presented.

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.

The Indicating FTA Elute Cartridge

PubMed Central

de Bie, Roosmarie P.; Schmeink, Channa E.; Bakkers, Judith M.J.E.; Snijders, Peter J.F.; Quint, Wim G.V.; Massuger, Leon F.A.G.; Bekkers, Ruud L.M.; Melchers, Willem J.G.

2011-01-01

The clinically validated high-risk human papillomavirus (hrHPV) Hybrid Capture 2 (HC2) and GP5+/6+-PCR assays were analyzed on an Indicating FTA Elute cartridge (FTA cartridge). The FTA cartridge is a solid dry carrier that allows safe transport of cervical samples. FTA cartridge samples were compared with liquid-based samples for hrHPV and high-grade cervical intraepithelial neoplasia (CIN) detection. One cervical sample was collected in a liquid-based medium, and one was applied to the FTA cartridge. DNA was eluted directly from the FTA cartridge by a simple elution step. HC2 and GP5+/6+-PCR assays were performed on both the liquid-based and the FTA-eluted DNA of 88 women. Overall agreement between FTA and liquid-based samples for the presence of hrHPV was 90.9% with GP5+/6+-PCR and 77.3% with HC2. The sensitivity for high-grade CIN of hrHPV testing on the FTA cartridges was 84.6% with GP5+/6+-PCR and only 53.8% with HC2. By comparison, these sensitivities on liquid-based samples were 92.3% and 100% for GP5+/6+-PCR and HC2, respectively. Therefore, the FTA cartridge shows reasonably good overall agreement for hrHPV detection with liquid-based media when using GP5+/6+-PCR but not HC2 testing. Even with GP5+/6+-PCR, the FTA cartridge is not yet capable of detecting all high-grade CIN lesions. PMID:21704269

Determination of vigabatrin in human plasma and urine by high-performance liquid chromatography with UV-Vis detection.

PubMed

Cetin, Sevil Müge; Atmaca, Sedef

2004-03-26

A simple and reliable high-performance liquid chromatographic (HPLC) method with UV-Vis detection has been developed and validated for the determination of vigabatrin (VG) in human plasma and urine. The samples were pre-column derivatizated with 1,2-naphthoquinone-4-sulphonic acid sodium salt (NQS). A good chromatographic separation was achieved on a C18 column with a mobile phase consisting of acetonitrile and 10 mM orthophosphoric acid (pH 2.5) gradient elution. Tranexamic acid was used as an internal standard (I.S.). The method was linear over the concentration range of 0.8-30.0 microg/ml for both samples. The method is precise (relative standard deviation (R.S.D.) <9.13%) and accurate (relative mean error (RME) <-8.75%); analytical recoveries were 81.07% for plasma and 83.05% for urine. The assay was applied to pharmacokinetic study in a healthy volunteer after a single oral administration of 1 g of vigabatrin.

[Simultaneous determination of 15 industrial synthetic dyes in condiment by solid phase extraction-high performance liquid chromatography].

PubMed

Liu, Min; Li, Xiaolin; Bie, Wei; Wang, Minglin; Feng, Qian

2011-02-01

A new method was established for the determination of 15 industrial synthetic dyes in condiment by solid phase extraction-high performance liquid chromatography (SPE-HPLC). The samples were extracted by methanol-water (1:1, v/v) and purified by a solid phase extraction column. Then, the chromatographic separation was achieved on a Luna C18 column by linear gradient elution. The mobile phase was 10 mmol/L ammonium acetate-acetonitrile (containing 1% acetic acid). The results showed that the 15 industrial synthetic dyes can be separated efficiently. The recoveries of the 15 industrial synthetic dyes spiked in condiment were between 84.6% and 114.2% with the relative standard deviations of 0.9% - 10.3%. The limits of detection of this method was 0.05 - 0.18 mg/kg for the 15 industrial synthetic dyes. The method is simple, sensitive, accurate, repeatable and can be used for simultaneous determination of the 15 illegally added industrial synthetic dyes.

Determination of ochratoxin A in fruit juice by high-performance liquid chromatography after vortex-assisted emulsification microextraction based on solidification of floating organic drop.

PubMed

Asadi, Mohammad

2018-03-01

A rapid, simple, and green vortex-assisted emulsification microextraction method based on solidification of floating organic drop was developed for the extraction and determination of ochratoxin A (OTA) with high-performance liquid chromatography. Some factors influencing the extraction efficiency of OTA such as the type and volume of extraction solvent, sample pH, salt concentration, vortex time, and sample volume were optimized. Under optimized conditions, the calibration curve exhibited linearity in the range of 50.0-500 ng L -1 with a coefficient of determination higher than 0.999. The limit of detection was 15.0 ng L -1 . The inter- and intra-assays relative standard deviations were in a range of 4.7-8.7%. The accuracy of the developed method was investigated through recovery experiments, and it was successfully used for the quantification of OTA in 40 samples of fruit juice.

Determination and validation of a simple high-performance liquid chromatographic method for simultaneous assay of iprodione and vinclozolin in human urine.

PubMed

Carlucci, Giuseppe; Pasquale, Dorina Di; Ruggieri, Fabrizio; Mazzeo, Pietro

2005-12-15

A method based on solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) was developed for the simultaneous determination of 3-(3,5-diclorophenyl)-5-ethenyl-5-methyl-2,4-oxazolidinedione (vinclozolin) and 3-(3,5-diclorophenyl)-N-(1-methylethyl)-2,4-dioxo-1-imidazolidinecarboxamide (iprodione) in human urine. Urine samples containing vinclozolin and iprodione were collected by solid phase extraction using C(18) cartridges. The chromatographic separation was achieved on a Spherisorb ODS2 (250 mm x 4.6 mm, 5 microm) column with an isocratic mobile phase of acetonitrile-water (60:40, v/v). Detection was UV absorbance at 220 nm. The calibration graphs were linear from 30 to 1000 ng/mL for the two fungicides. Intra- and inter-day R.S.D. did not exceed 2.9%. The quantitation limit was 50 ng/mL for vinclozolin and 30 ng/mL for iprodione, respectively.

[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.

Analysis of the influence of processing of stir-baking with glycyrrhizae on the main components of Euodiae Fructus by high-performance liquid chromatography with diode array detector.

PubMed

Hu, Jue; Wu, Xin; Cao, Gang; Chen, Xiaocheng

2014-01-01

Euodiae Fructus is one of the most commonly used Chinese herbs in China. Specifically, the crude Euodiae Fructus and its processed products of Gancao Zhi Pin are used clinically for the treatment of different diseases. In order to improve the quality control standard and evaluate the crude and processed Euodiae Fructus, in this study, a simple and sensitive high-performance liquid chromatography-diode array detector method was developed for the simultaneous determination of five major compounds in Euodiae Fructus. The results indicated that the five components had significant linear relation (r(2) ≥ 0.9997) between the peak area and the injected concentration. The average recoveries of the five components were in the range from 97.38% to 102.56%. Overall intra- and inter-day variations were less than 1.36%. The developed method can be applied to the intrinsic quality control of crude and processed Euodiae Fructus.

Determination of N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine and its metabolites in human plasma and urine by column-switching high-performance liquid chromatography with ultraviolet detection.

PubMed

Ono, I; Matsuda, K; Kanno, S

1997-05-09

A simple, rapid and sensitive two column-switching high-performance liquid chromatographic (HPLC) method with ultraviolet detection at 210 nm has been developed for the determination of N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine (AY4166, I) and its seven metabolites in human plasma and urine. Measurements of I and its metabolites were carried out by two column-switching HPLC, because metabolites were classified into two groups according to their retention times. After purification of plasma samples using solid-phase extraction and direct dilution of urinary samples, I and each metabolite were injected into HPLC. The calibration graphs for plasma and urinary samples were linear in the ranges 0.1 to 10 microg ml(-1) and 0.5 to 50 microg ml(-1), respectively. Recoveries of I and its seven metabolites were over 88% by the standard addition method and the relative standard deviations of I and its metabolites were 1-6%.

[Simultaneous determination of sugar alcohols and sugars in functional foods by precolumn ultraviolet derivatization--high performance liquid chromatography].

PubMed

Liu, Ya-Pan; Ran, Xue-Qin; Chen, Lu-Ying; Zhang, Jing; Ruan, Jia; Li, Yong-Xin; Sun, Chengjun

2014-09-01

To establish a method using precolumn ultraviolet derivatization coupled with high performance liquid chromatography (HPLC) for simultaneous determination of erythritol, xylitol, galactitol, sorbitol, mannitol, maltitol, glucose and sucrose in functional foods. Target sugar alcohols and sugars in food samples were extracted in water by ultrasonic method and then reacted with benzoyl chloride to form violet-absorbing products, which were separated on a C18 column with gradient elution using methanol and water as mobile phase. The experiment was performed using a flow rate of 1.00 mL/min, column temperature at 30 degrees C and detected wavelength at 232 nm. The linear correlation coefficients of all the derivatives were more than 0. 999. The detection limits of the method were as low as 2. 2 microg/mL. The average recoveries were 89.6%-117.0%, with intraday relative standard derivations lower than 5%. This method is simple, inexpensive and easy to operate and it is suitable for the determination of sugar alcohols and glucose and sucrose in functional foods.

Application of Silver Ion High-Performance Liquid Chromatography for Quantitative Analysis of Selected n-3 and n-6 PUFA in Oil Supplements.

PubMed

Czajkowska-Mysłek, Anna; Siekierko, Urszula; Gajewska, Magdalena

2016-04-01

The aim of this study was to develop a simple method for simultaneous determination of selected cis/cis PUFA-LNA (18:2), ALA (18:3), GLA (18:3), EPA (20:5), and DHA (22:6) by silver ion high-performance liquid chromatography coupled to a diode array detector (Ag-HPLC-DAD). The separation was performed on three Luna SCX Silver Loaded columns connected in series maintained at 10 °C with isocratic elution by 1% acetonitrile in n-hexane. The applied chromatographic system allowed a baseline separation of standard mixture of n-3 and n-6 fatty acid methyl esters containing LNA, DHA, and EPA and partial separation of ALA and GLA positional isomers. The method was validated by means of linearity, precision, stability, and recovery. Limits of detection (LOD) for considered PUFA standard solutions ranged from 0.27 to 0.43 mg L(-1). The developed method was used to evaluate of n-3 and n-6 fatty acids contents in plant and fish softgel oil capsules, results were compared with reference GC-FID based method.

Evaluation of a new modified QuEChERS method for the monitoring of carbamate residues in high-fat cheeses by using UHPLC-MS/MS.

PubMed

Hamed, Ahmed M; Moreno-González, David; Gámiz-Gracia, Laura; García-Campaña, Ana M

2017-01-01

A simple and efficient method for the determination of 28 carbamates in high-fat cheeses is proposed. The methodology is based on a modified quick, easy, cheap, effective, rugged, and safe procedure as sample treatment using a new sorbent (Z-Sep + ) followed by ultra-high performance liquid chromatography with tandem mass spectrometry determination. The method has been validated in different kinds of cheese (Gorgonzola, Roquefort, and Camembert), achieving recoveries of 70-115%, relative standard deviations lower than 13% and limits of quantification lower than 5.4 μg/kg, below the maximum residue levels tolerated for these compounds by the European legislation. The matrix effect was lower than ±30% for all the studied pesticides. The combination of ultra-high performance liquid chromatography and tandem mass spectrometry with this modified quick, easy, cheap, effective, rugged, and safe procedure using Z-Sep + allowed a high sample throughput and an efficient cleaning of extracts for the control of these residues in cheeses with a high fat content. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Endoscope system with plasma flushing and coaxial round jet nozzle for off-pump cardiac surgery.

PubMed

Horiuchi, Tetsuya; Masamune, Ken; Iwase, Yuki; Ymashita, Hiromasa; Tsukihara, Hiroyuki; Motomura, Noboru; Ohta, Yuji; Dohi, Takeyoshi

2011-07-01

To develop a new endoscope for performing simple surgical tasks inside the blood-filled cardiac atrium/chamber, that is, "off-pump" cardiac surgeries. We developed the endoscope system with plasma flushing and coaxial round jet nozzle. The "plasma flushing" system was invented to observe the interior of the blood-filled heart by displacing blood cells in front of the endoscope tip. However, some areas could not be observed with simple flushing of the liquid because the flushed liquid mixed with blood. Further, a large amount of liquid had to be flushed, which posed a risk of cardiac damage caused by excess volume. Therefore, to safely capture high-resolution images of the interior of the heart, an endoscope with a coaxial round jet nozzle through which plasma is flushed has been developed. And to reduce the volume of flushed liquid, the synchronization system of heartbeat and the endoscope system with plasma flushing has been developed. We conducted an in vivo experiment to determine whether we could observe intracardiac tissues in swine without the use of a heart-lung machine. As a result, we successfully observed intracardiac tissues without using a heart-lung machine. By using a coaxial nozzle, we could even observe the tricuspid valve. Moreover, we were able to save up to 30% of the flushed liquid by replacing the original system with a synchronization system. And we evaluated the performance of the endoscope with the coaxial round jet nozzle by conducting fluid analysis and an in vitro experiment. We successfully observed intracardiac tissues without using a heart-lung machine. By using a coaxial nozzle, we could even observe the tricuspid valve. And by replacing an original system to a synchronization system, we were able to save up to 30% of the flushed liquid. As a follow-up study, we plan to create a surgical flexible device for valve disease that can grasp, staple, and repair cardiac valves by endoscopic visualization.

Simple and simultaneous determination of the hiv-protease inhibitors amprenavir, atazanavir, indinavir, lopinavir, nelfinavir, ritonavir and saquinavir plus M8 nelfinavir metabolite and the nonnucleoside reverse transcriptase inhibitors efavirenz and nevirapine in human plasma by reversed-phase liquid chromatography.

PubMed

Poirier, Jean-Marie; Robidou, Pascal; Jaillon, Patrice

2005-04-01

Several studies suggest that therapeutic drug monitoring of protease inhibitors and nonnucleoside reverse transcriptase inhibitors may contribute to the clinical outcome of HIV-infected patients. Because of the growing number of antiretroviral drugs and of drug combinations than can be administered to these patients, an accurate high-performance liquid chromatographic (HPLC) method allowing the simultaneous determination of these drugs may be useful. To date, the authors present the first simultaneous HPLC determination of the new protease inhibitor atazanavir with all the others currently in use (M8 nelfinavir metabolite included) and the 2 widely used nonnucleoside reverse transcriptase inhibitors efavirenz and nevirapine. This simple HPLC method allows the analysis all these drugs at a single ultraviolet wavelength following a 1-step liquid-liquid extraction procedure. A 500-muL plasma sample was spiked with internal standard and subjected to liquid-liquid extraction using by diethyl ether at pH 10. HPLC was performed using a Symmetry Shield RP18 and gradient elution. All the drugs of interest and internal standard were detected with ultraviolet detection at 210 nm. Calibration curves were linear in the range 50-10,000 ng/mL. The observed concentrations of the quality controls at plasma concentrations ranging from 50 to 5000 ng/mL for these drugs showed that the overall accuracy varied from 92% to 104% and 92% to 106% for intraday and day-to-day analysis, respectively. No metabolites of the assayed compounds or other drugs commonly coadministered to HIV-positive patients were found to coelute with the drugs of interest or with the internal standard. This assay was developed for the purpose of therapeutic monitoring (TDM) in HIV-infected patients.

Determination of pharmaceutical and illicit drugs in oral fluid by ultra-high performance liquid chromatography-tandem mass spectrometry.

PubMed

Di Corcia, D; Lisi, S; Pirro, V; Gerace, E; Salomone, A; Vincenti, M

2013-05-15

A simple and extremely fast procedure for the quantitative determination in oral fluid samples of 44 substances, including the most common drugs of abuse and several pharmaceutical drugs, was developed and fully validated. Preliminary sample treatment was limited to protein precipitation. The resulting acetonitrile solution was directly injected into an ultra-high performance liquid chromatograph (UHPLC) equipped with a C18 column (100mm×2.1mm, 1.7μm). The mobile phase eluted with linear gradient (water/formic acid 5mM: acetonitrile/formic acid 5mM; v:v) from 98:2 to 0:100 in 5.0min, followed by isocratic elution at 100% B for 1.0min. The flow rate was 0.6mL/min and the total run time was 9.0min including re-equilibration at the initial conditions. The analytes were revealed by a triple quadrupole mass spectrometer operating in the selected reaction monitoring mode. The method proved to be simple, accurate, rapid and highly sensitive, allowing the simultaneous detection of all compounds. The ease of sample treatment, together with the wide range of detectable substances, all with remarkable analytical sensitivity, make this procedure ideal for the screening of large populations in several forensic and clinical contexts, whenever oral fluid sampling has to be preferred to blood sampling, as for example in short retrospective investigations. Copyright © 2013 Elsevier B.V. All rights reserved.

Anion-exchange high-performance liquid chromatography with post-column detection for the analysis of phytic acid and other inositol phosphates

NASA Technical Reports Server (NTRS)

Rounds, M. A.; Nielsen, S. S.; Mitchell, C. A. (Principal Investigator)

1993-01-01

The use of gradient anion-exchange HPLC, with a simple post-column detection system, is described for the separation of myo-inositol phosphates, including "phytic acid" (myo-inositol hexaphosphate). Hexa-, penta-, tetra-, tri- and diphosphate members of this homologous series are clearly resolved within 30 min. This method should facilitate analysis and quantitation of "phytic acid" and other inositol phosphates in plant, food, and soil samples.

Stereoselective determination of vigabatrin enantiomers in human plasma by high performance liquid chromatography using UV detection.

PubMed

Franco, Valentina; Mazzucchelli, Iolanda; Fattore, Cinzia; Marchiselli, Roberto; Gatti, Giuliana; Perucca, Emilio

2007-07-01

A rapid and simple high-performance liquid chromatographic method for the determination of the R-(-)- and S-(+)-enantiomers of the antiepileptic drug vigabatrin in human plasma is described. After adding the internal standard (1-aminomethyl-cycloheptyl-acetic acid), plasma samples (200 microL) are deproteinized with acetonitrile and the supernatant is derivatized with 2,4,6 trinitrobenzene sulfonic acid (TNBSA). Separation is achieved on a reversed-phase cellulose-based chiral column (Chiralcel-ODR, 250 mm x 4.6 mm i.d.) using 0.05 M potassium hexafluorophosphate (pH 4.5)/acetonitrile/ethanol (50:40:10 vol/vol/vol) as mobile phase at a flow-rate of 0.9 mL/min. Chromatographic selectivity is improved by concentrating the derivatives on High Performance Extraction Disk Cartridges prior to injection. Detection is at 340 nm. Calibration curves are linear (r(2)> or =0.999) over the range of 0.5-40 microg/mL for each enantiomer, with a limit of quantification of 0.5 microg/mL for both analytes. The assay is suitable for therapeutic drug monitoring and for single-dose pharmacokinetic studies in man.

Simultaneous determination of 11 preservatives in cosmetics by high-performance liquid chromatography.

PubMed

Aoyama, Airin; Doi, Takahiro; Tagami, Takaomi; Kajimura, Keiji

2014-10-01

Preservatives prevent the growth of microorganisms in foods, pharmaceuticals and cosmetics. There exist numerous restrictions regarding the maximum allowable levels of preservatives in cosmetics. We analyzed 11 regulated preservatives in commercial cosmetics and manufacturers need to analyze their products for quality control purposes. However, methods used in previous studies to date have been inadequate for use by public institutions and manufacturers. Therefore, an effective, scalable method for the analysis of preservatives in cosmetics is required. We developed a novel method for the simultaneous determination of 11 regulated preservatives in cosmetics by high-performance liquid chromatography (HPLC). We applied the samples to a C18 column in a simple mobile phase (5 mmol/L ammonium formate solution and acetonitrile) with gradient elution at a flow rate of 1.0 mL/min at a single wavelength (230 nm). The correlation coefficients of the calibration curves were >0.997. The percent recoveries were 92.8-111.9% and the relative standard deviations were <4.3% (n = 6). The peak resolution for all preservatives was >1.9. Because of the simple conditions for isolation and complete separation, the HPLC method can be effectively applied to the analysis of preservatives in commercially retailed cosmetics. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Profiling of components of rhizoma et radix polygoni cuspidati by high-performance liquid chromatography with ultraviolet diode-array detector and ion trap/time-of-flight mass spectrometric detection.

PubMed

Fu, Jinfeng; Wang, Min; Guo, Huimin; Tian, Yuan; Zhang, Zunjian; Song, Rui

2015-01-01

Rhizoma et Radix Polygoni Cuspidati (Huzhang in Chinese, HZ) is a traditional medicinal plant in China. Many of the components of HZ have been proved to be bioactive while it is difficult to conduct a comprehensive chemical profiling of HZ as a consequence of the absence of efficient separation system and sensitive detective means. We developed a simple and effective method for comprehensive characterization of constituents in HZ. To develop a simple and effective method to characterize the components in HZ and provide useful information for subsequent metabolic studies of HZ. The components in HZ aqueous extract were characterized by using high performance liquid chromatography with UV diode-array detector (HPLC-DAD) and ion trap/time-of-flight mass spectrometric detection (HPLC-IT/TOF). Stilbenes, anthraquinones, gallates and tannins, naphthalenes and some other compounds were identified and confirmed by diagnostic fragment ions with accurate mass measurements, characteristic fragmentation pathways and relevant published literatures. Among the 238 constituents detected in HZ, a total number of 74 constituents were identified unambiguously or tentatively, including 29 compounds reported for the first time in HZ. The identification and structure elucidation of these chemicals provided essential data for quality control and further in vivo metabolic studies of HZ. Key words: Polygonum cuspidatum, HPLC-DAD, HPLC-IT/TOF, qualitative analysis.

An efficient preparative procedure for main flavonoids from the peel of Trichosanthes kirilowii Maxim. using polyamide resin followed by semi-preparative high performance liquid chromatography.

PubMed

Li, Aifeng; Sun, Ailing; Liu, Renmin; Zhang, Yongqing; Cui, Jichun

2014-08-15

In this study, a simple and efficient preparative procedure was developed for preparation of seven flavonoids from the peel of Trichosanthes kirilowii Maxim. using polyamide resin followed by semi-preparative high performance liquid chromatography (SPHPLC). First, the ethyl acetate fraction from the peel of T. kirilowii Maxim. obtained "prefractionation" using polyamide resin, which yielded two subfractions. And then the two subfractions were isolated by SPHPLC with an isocratic elution of methanol-water. Finally, seven known flavonoids were purified from 35 g of ethyl acetate extract including quercetin-3-O-[α-l-rhamnose (1→2)-β-d-glucopyranosyl]-5-O-β-d-glucopyranoside (19 mg), quercetin-3-O-rutinoside (24 mg), apigenin-7-O-β-d-glucopyranoside (10mg), diosmetin-7-O-β-d-glucopyranoside (45 mg), luteolin (21 mg), apigenin (15 mg), and diosmetin (56 mg). The purities of the compounds were determined by HPLC and the chemical structures were confirmed by UV and NMR analysis. In the present study, a simple, effective, and rapid procedure was established for preparative separation of multiple components from the peel of T. kirilowii Maxim. Furthermore, it was scalable and economical, so it was a promising basis for large-scale preparation of flavonoids from other plant extracts. Copyright © 2014. Published by Elsevier B.V.

Simultaneous determination of quercetin, kaempferol and isorhamnetin accumulated human breast cancer cells, by high-performance liquid chromatography.

PubMed

Wang, Yi; Cao, Jiang; Weng, Jian-Hua; Zeng, Su

2005-09-01

Quercetin, kaempferol and isorhamnetin are the most important constituents in ginkgo flavonoids. A simple, rapid and sensitive high-performance liquid chromatography method was developed to simultaneously determine quercetin, kaempferol and isorhamnetin absorped by human breast cancer cells. Cells were treated with ginkgo flavonols and then lysed with Triton-X 100. The flavonols in the samples were measured by RP-HPLC with a C18 column after a simple extraction with a mixture of ether and acetone. The mobile phase contained phosphate buffer (pH 2.0; 10 mM) tetrahydrofuran, methanol and isopropanol (65:15:10:20, v/v/v/v). The ultraviolet detector was operated at 380 nm. The calibration curve was linear from 0.1 to 1.0 microM (r > 0.999) for each flavonol. The mean extraction efficiency was about 70%. The recovery of the assay was between 98.9 and 100.6%. The limit of detection was 0.01 microM for quercetin and kaempferol and 0.05 microM for isorhamnetin. The limit of quantitation was 0.1 microM (R.S.D.<10%) for each flavonol. The intra- and inter-day coefficients of variation were less than 10% (R.S.D.). The validated method was applied to quantify quercetin, kaempferol and isorhamnetin in human breast cancer Bcap37 and Bcap37/MDR1 cells.

Catalytic Conversion of Carbohydrates to Levulinate Ester over Heteropolyanion-Based Ionic Liquids.

PubMed

Song, Changhua; Liu, Sijie; Peng, Xinwen; Long, Jinxing; Lou, Wenyong; Li, Xuehui

2016-12-08

An efficient one-pot approach for the production of levulinate ester from renewable carbohydrates is demonstrated over heteropolyanion-based ionic liquid (IL-POM) catalysts with alcohols as the promoters and solvents. The relationships between the structure, acidic strength, and solubility of the IL-POM in methanol and the catalytic performance were studied intensively. A cellulose conversion of 100 % could be achieved with a 71.4 % yield of methyl levulinate over the catalyst [PyPS] 3 PW 12 O 40 [PyPS=1-(3-sulfopropyl)pyridinium] at 150 °C for 5 h. This high efficiency is ascribed to the reasonably high activity of the ionic liquid (IL) catalyst and reaction coupling with rapid in situ esterification of the generated levulinic acid with the alcohol promoter, which allows the insolubility of cellulose encountered in biomass conversion to be overcome. Furthermore, the present process exhibits high feedstock adaptability for typical carbohydrates and handy catalyst recovery by a simple self-separation procedure through temperature control. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A rapid method for the simultaneous determination of 25 anti-hypertensive compounds in dietary supplements using ultra-high-pressure liquid chromatography.

PubMed

Heo, Seok; Yoo, Geum Joo; Choi, Ji Yeon; Park, Hyoung Joon; Park, Sung-Kwan; Baek, Sun Young

2016-11-01

A novel, stable, simple and specific ultra-performance liquid chromatography method with ultraviolet detection (205 nm) for the simultaneous analysis of 25 anti-hypertensive substances was developed. The method was validated according to the International Conference of Harmonisation guidelines with respect to linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ) and stability. From the ultra-performance liquid chromatography results, we identified the LOD and LOQ of solid samples to be 0.20-1.00 and 0.60-3.00 μg ml -1 , respectively, while those of liquid samples were 0.30-1.20 and 0.90-3.60 μg ml -1 , respectively. The linearity exceeded 0.9999, and the intra- and inter-day precisions were 0.15-6.48% and 0.28-8.67%, respectively. The intra- and inter-day accuracies were 82.25-111.42% and 80.70-115.64%, respectively, and the stability was lower than 12.9% (relative standard deviation). This method was applied to the monitoring of 97 commercially available dietary supplements obtained in Korea, such as pills, soft capsules, hard capsules, liquids, powders and tablets. The proposed method is accurate, precise and of high quality, and can be used for the routine, reproducible analysis and control of 25 anti-hypertensive substances in various dietary supplements. The work presented herein may help to prevent incidents related to food adulteration and restrict the illegal food market.

Deep eutectic solvent-based ultrasound-assisted dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for the determination of ultraviolet filters in water samples.

PubMed

Wang, Huazi; Hu, Lu; Liu, Xinya; Yin, Shujun; Lu, Runhua; Zhang, Sanbing; Zhou, Wenfeng; Gao, Haixiang

2017-09-22

In the present study, a simple and rapid sample preparation method designated ultrasound-assisted dispersive liquid-liquid microextraction based on a deep eutectic solvent (DES) followed by high-performance liquid chromatography with ultraviolet (UV) detection (HPLC-UVD) was developed for the extraction and determination of UV filters from water samples. The model analytes were 2,4-dihydroxybenzophenone (BP-1), benzophenone (BP) and 2-hydroxy-4-methoxybenzophenone (BP-3). The hydrophobic DES was prepared by mixing trioctylmethylammonium chloride (TAC) and decanoic acid (DecA). Various influencing factors (selection of the extractant, amount of DES, ultrasound duration, salt addition, sample volume, sample pH, centrifuge rate and duration) on UV filter recovery were systematically investigated. Under optimal conditions, the proposed method provided good recoveries in the range of 90.2-103.5% and relative standard deviations (inter-day and intra-day precision, n=5) below 5.9%. The enrichment factors for the analytes ranged from 67 to 76. The limits of detection varied from 0.15 to 0.30ngmL -1 , depending on the analytes. The linearities were between 0.5 and 500ngmL -1 for BP-1 and BP and between 1 and 500ngmL -1 for BP-3, with coefficients of determination greater than 0.99. Finally, the proposed method was applied to the determination of UV filters in swimming pool and river water samples, and acceptable relative recoveries ranging from 82.1 to 106.5% were obtained. Copyright © 2017. Published by Elsevier B.V.

Analysis of serotonin concentrations in human milk by high-performance liquid chromatography with fluorescence detection.

PubMed

Chiba, Takeshi; Maeda, Tomoji; Tairabune, Tomohiko; Tomita, Takashi; Sanbe, Atsushi; Takeda, Rika; Kikuchi, Akihiko; Kudo, Kenzo

2017-03-25

Serotonin (5-hydroxytryptamine, 5-HT) plays an important role in milk volume homeostasis in the mammary gland during lactation; 5-HT in milk may also affect infant development. However, there are few reports on 5-HT concentrations in human breast milk. To address this issue, we developed a simple method based on high-performance liquid chromatography with fluorescence detection (HPLC-FD) for measuring 5-HT concentrations in human breast milk. Breast milk samples were provided by four healthy Japanese women. Calibration curves for 5-HT in each sample were prepared with the standard addition method between 5 and 1000 ng/ml, and all had correlation coefficients >0.999. The recovery of 5-HT was 96.1%-101.0%, with a coefficient of variation of 3.39%-8.62%. The range of 5-HT concentrations estimated from the calibration curves was 11.1-51.1 ng/ml. Thus, the HPLC-FD method described here can effectively extract 5-HT from human breast milk with high reproducibility. Copyright © 2017 Elsevier Inc. All rights reserved.

HPLC/Fluorometric Detection of Carvedilol in Real Human Plasma Samples Using Liquid-Liquid Extraction.

PubMed

Yilmaz, Bilal; Arslan, Sakir

2016-03-01

A simple, rapid and sensitive high-performance liquid chromatography (HPLC) method has been developed to quantify carvedilol in human plasma using an isocratic system with fluorescence detection. The method included a single-step liquid-liquid extraction with diethylether and ethylacetate mixture (3 : 1, v/v). HPLC separation was carried out by reversed-phase chromatography with a mobile phase composed of 20 mM phosphate buffer (pH 7)-acetonitrile (65 : 35, v/v), pumped at a flow rate of 1.0 mL/min. Fluorescence detection was performed at 240 nm (excitation) and 330 nm (emission). The calibration curve for carvedilol was linear from 10 to 250 ng/mL. Intra- and interday precision values for carvedilol in human plasma were <4.93%, and accuracy (relative error) was better than 4.71%. The analytical recovery of carvedilol from human plasma averaged out to 91.8%. The limits of detection and quantification of carvedilol were 3.0 and 10 ng/mL, respectively. Also, the method was successfully applied to three patients with hypertension who had been given an oral tablet of 25 mg carvedilol. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Stereolithography of perfluoropolyethers for the microfabrication of robust omniphobic surfaces

NASA Astrophysics Data System (ADS)

Credi, Caterina; Levi, Marinella; Turri, Stefano; Simeone, Giovanni

2017-05-01

In this work, we provide a simple and straightforward method for the fabrication of stable highly hydrophobic and oleophobic surfaces by applying stereolithography (SL) to perfluoropolyethers (PFPEs). Inspired by the liquid repellency widely shown in nature, our approach enables to easily mimic the interplay between the chemistry and physics by microtexturing low surface tension PFPEs. To this end, UV-curable resins suitable for SL-processing were formulated by blending multifunctional (meth-)acrylates PFPEs oligomers with photoinitiator and visible dyes whose content was tuned to tailor resin SL sensitivities. Photocalorimetric studies were also performed to investigate the curing behavior of the different formulations upon SL light exposure. Being the first example of stereolithography applied to PFPEs, stereolithographic processability of new developed PFPEs photopolymer was compared with a standard photoresist taken as benchmark (DL260®). Optimized formulations were characterized by reduced laser penetration depth (<75 μm) and small critical energies thus enabling for fast printing of micrometric structures. Arrays of cylindrical pillars (85 μm diameter, 400 μm height) characterized by varied pillars spacing (200 ÷ 350 μm) were rapidly printed with high fidelity as attested by SEM examination. Contact angle measurements in static and dynamic conditions were performed to investigate the surface properties of textured samples using water and oil as the probing liquids. PFPEs liquid repellent performances were compared with those from DL260® textured surfaces arrayed by SL. High water contact angles coupled with low hysteresis asserted that high hydrophobic surfaces were successfully obtained and best-performing textured surfaces were also characterized by high oil repellency. Finally, this study demonstrated that omniphobic surfaces can be easily realized via a single-step, cost-effective, and time-saving process.

Fluorescent high-performance liquid chromatographic analysis of vigabatrin enantiomers after derivatizing with naproxen acyl chloride.

PubMed

Hsieh, Chun-Yu; Wang, Shing-Yaw; Kwan, Aij-Lie; Wu, Hsin-Lung

2008-01-18

Vigabatrin is widely used as an anticonvulsant in the treatment of seizures. Vigabatrin is usually supplied as racemate in formulation, but only the (S)-(+)-enantiomer of vigabatrin is pharmacologically active. A simple and sensitive liquid chromatographic method is described for the separation and quantification of vigabatrin enantiomers. The method is based on derivatizing racemic vigabatrin with a fluorescent chiral reagent (naproxen acyl chloride). The resulting diastereomeric derivatives are highly responsive to a fluorimetric detector (lambda(ex)=230 nm, lambda(em)=350 nm). The lower quantitation limit of the method is attainable at 25 nM for (S)-(+)-vigabatrin or (R)-(-)-vigabatrin with a detection limit of about 2.5 nM (S/N=3 with 10 microl injected). Application of the method to the analysis of vigabatrin in serum of dosed patients proved feasible.

Nonesterified fatty acid determination for functional lipidomics: comprehensive ultrahigh performance liquid chromatography-tandem mass spectrometry quantitation, qualification, and parameter prediction.

PubMed

Hellmuth, Christian; Weber, Martina; Koletzko, Berthold; Peissner, Wolfgang

2012-02-07

Despite their central importance for lipid metabolism, straightforward quantitative methods for determination of nonesterified fatty acid (NEFA) species are still missing. The protocol presented here provides unbiased quantitation of plasma NEFA species by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Simple deproteination of plasma in organic solvent solution yields high accuracy, including both the unbound and initially protein-bound fractions, while avoiding interferences from hydrolysis of esterified fatty acids from other lipid classes. Sample preparation is fast and nonexpensive, hence well suited for automation and high-throughput applications. Separation of isotopologic NEFA is achieved using ultrahigh-performance liquid chromatography (UPLC) coupled to triple quadrupole LC-MS/MS detection. In combination with automated liquid handling, total assay time per sample is less than 15 min. The analytical spectrum extends beyond readily available NEFA standard compounds by a regression model predicting all the relevant analytical parameters (retention time, ion path settings, and response factor) of NEFA species based on chain length and number of double bonds. Detection of 50 NEFA species and accurate quantification of 36 NEFA species in human plasma is described, the highest numbers ever reported for a LC-MS application. Accuracy and precision are within widely accepted limits. The use of qualifier ions supports unequivocal analyte verification. © 2012 American Chemical Society

A search for two types of transverse excitations in liquid polyvalent metals at ambient pressure: An ab initio molecular dynamics study of collective excitations in liquid Al, Tl and Ni

NASA Astrophysics Data System (ADS)

Bryk, Taras; Demchuk, Taras; Jakse, Noël; Wax, Jean-François

2018-02-01

Recent findings of pressure-induced emergence of unusual high-frequency contribution to transverse current spectral functions in several simple liquid metals at high pressures raised a question whether similar features can be observed in liquid metals at ambient conditions. We report here analysis of ab initio molecular dynamics-derived longitudinal (L) and transverse (T) current spectral functions and corresponding dispersions of collective excitations in liquid polyvalent metals Al, Tl, Ni. We have not found evidences of the second branch of high-frequency transverse modes in liquid Al and Ni, while in the case of liquid Tl they were clearly present in transverse dynamics. The vibrational density of states for liquid Tl has a pronounced high-frequency shoulder, which is located right in the frequency range of the second high-frequency transverse branch, while for liquid Al and Ni the vibrational density of states has only a weak indication of possible high-frequency shoulder. The origin of specific behavior of transverse excitations in liquid Tl is discussed.

Algebraic perturbation theory for dense liquids with discrete potentials

NASA Astrophysics Data System (ADS)

Adib, Artur B.

2007-06-01

A simple theory for the leading-order correction g1(r) to the structure of a hard-sphere liquid with discrete (e.g., square-well) potential perturbations is proposed. The theory makes use of a general approximation that effectively eliminates four-particle correlations from g1(r) with good accuracy at high densities. For the particular case of discrete perturbations, the remaining three-particle correlations can be modeled with a simple volume-exclusion argument, resulting in an algebraic and surprisingly accurate expression for g1(r) . The structure of a discrete “core-softened” model for liquids with anomalous thermodynamic properties is reproduced as an application.

Multiplex Liquid Chromatography-Tandem Mass Spectrometry Assay for Simultaneous Therapeutic Drug Monitoring of Ribavirin, Boceprevir, and Telaprevir

PubMed Central

Aouri, Manel; Moradpour, Darius; Cavassini, Matthias; Mercier, Thomas; Buclin, Thierry; Csajka, Chantal; Telenti, Amalio; Rauch, Andri

2013-01-01

New directly acting antivirals (DAAs) that inhibit hepatitis C virus (HCV) replication are increasingly used for the treatment of chronic hepatitis C. A marked pharmacokinetic variability and a high potential for drug-drug interactions between DAAs and numerous drug classes have been identified. In addition, ribavirin (RBV), commonly associated with hemolytic anemia, often requires dose adjustment, advocating for therapeutic drug monitoring (TDM) in patients under combined antiviral therapy. However, an assay for the simultaneous analysis of RBV and DAAs constitutes an analytical challenge because of the large differences in polarity among these drugs, ranging from hydrophilic (RBV) to highly lipophilic (telaprevir [TVR]). Moreover, TVR is characterized by erratic behavior on standard octadecyl-based reversed-phase column chromatography and must be separated from VRT-127394, its inactive C-21 epimer metabolite. We have developed a convenient assay employing simple plasma protein precipitation, followed by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for the simultaneous determination of levels of RBV, boceprevir, and TVR, as well as its metabolite VRT-127394, in plasma. This new, simple, rapid, and robust HPLC-MS/MS assay offers an efficient method of real-time TDM aimed at maximizing efficacy while minimizing the toxicity of antiviral therapy. PMID:23629707

Design and performance of a new continuous-flow sample-introduction system for flame infrared-emission spectrometry: Applications in process analysis, flow injection analysis, and ion-exchange high-performance liquid chromatography.

PubMed

Lam, C K; Zhang, Y; Busch, M A; Busch, K W

1993-06-01

A new sample introduction system for the analysis of continuously flowing liquid streams by flame infrared-emission (FIRE) spectrometry has been developed. The system uses a specially designed purge cell to strip dissolved CO(2) from solution into a hydrogen gas stream that serves as the fuel for a hydrogen/air flame. Vibrationally excited CO(2) molecules present in the flame are monitored with a simple infrared filter (4.4 mum) photometer. The new system can be used to introduce analytes as a continuous liquid stream (process analysis mode) or on a discrete basis by sample injection (flow injection analysis mode). The key to the success of the method is the new purge-cell design. The small internal volume of the cell minimizes problems associated with purge-cell clean-out and produces sharp, reproducible signals. Spent analytical solution is continuously drained from the cell, making cell disconnection and cleaning between samples unnecessary. Under the conditions employed in this study, samples could be analyzed at a maximum rate of approximately 60/h. The new sample introduction system was successfully tested in both a process analysis- and a flow injection analysis mode for the determination of total inorganic carbon in Waco tap water. For the first time, flame infrared-emission spectrometry was successfully extended to non-volatile organic compounds by using chemical pretreatment with peroxydisulfate in the presence of silver ion to convert the analytes into dissolved carbon dioxide, prior to purging and detection by the FIRE radiometer. A test of the peroxydisulfate/Ag(+) reaction using six organic acids and five sugars indicated that all 11 compounds were oxidized to nearly the same extent. Finally, the new sample introduction system was used in conjunction with a simple filter FIRE radiometer as a detection system in ion-exchange high-performance liquid chromatography. Ion-exchange chromatograms are shown for two aqueous mixtures, one containing six organic acids and the second containing six mono-, di-, and trisaccharides.

Incorporation of ionic liquid into porous polymer monoliths to enhance the separation of small molecules in reversed-phase high-performance liquid chromatography.

PubMed

Wang, Jiafei; Bai, Ligai; Wei, Zhen; Qin, Junxiao; Ma, Yamin; Liu, Haiyan

2015-06-01

An ionic liquid was incorporated into the porous polymer monoliths to afford stationary phases with enhanced chromatographic performance for small molecules in reversed-phase high-performance liquid chromatography. The effect of the ionic liquid in the polymerization mixture on the performance of the monoliths was studied in detail. While monoliths without ionic liquid exhibited poor resolution and low efficiency, the addition of ionic liquid to the polymerization mixture provides highly increased resolution and high efficiency. The chromatographic performances of the monoliths were demonstrated by the separations of various small molecules including aromatic hydrocarbons, isomers, and homologues using a binary polar mobile phase. The present column efficiency reached 27 000 plates/m, which showed that the ionic liquid monoliths are alternative stationary phases in the separation of small molecules by high-performance liquid chromatography. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A microcontroller-based microwave free-space measurement system for permittivity determination of lossy liquid materials.

PubMed

Hasar, U C

2009-05-01

A microcontroller-based noncontact and nondestructive microwave free-space measurement system for real-time and dynamic determination of complex permittivity of lossy liquid materials has been proposed. The system is comprised of two main sections--microwave and electronic. While the microwave section provides for measuring only the amplitudes of reflection coefficients, the electronic section processes these data and determines the complex permittivity using a general purpose microcontroller. The proposed method eliminates elaborate liquid sample holder preparation and only requires microwave components to perform reflection measurements from one side of the holder. In addition, it explicitly determines the permittivity of lossy liquid samples from reflection measurements at different frequencies without any knowledge on sample thickness. In order to reduce systematic errors in the system, we propose a simple calibration technique, which employs simple and readily available standards. The measurement system can be a good candidate for industrial-based applications.

Surface structure in simple liquid metals: An orbital-free first-principles study

NASA Astrophysics Data System (ADS)

González, D. J.; González, L. E.; Stott, M. J.

2006-07-01

Molecular dynamics simulations of the liquid-vapor interfaces in simple sp-bonded liquid metals have been performed using first-principles methods. Results are presented for liquid Li, Na, K, Rb, Cs, Mg, Ba, Al, Tl, and Si at thermodynamic conditions near their respective triple points, for samples of 2000 particles in a slab geometry. The longitudinal ionic density profiles exhibit a pronounced stratification extending several atomic diameters into the bulk, which is a feature already experimentally observed in liquid K, Ga, In, Sn, and Hg. The wavelength of the ionic oscillations shows a good scaling with the radii of the associated Wigner-Seitz spheres. The structural rearrangements at the interface are analyzed in terms of the transverse pair correlation function, the coordination number, and the bond-angle distribution between nearest neighbors. The valence electronic density profile also shows (weaker) oscillations whose phase, with respect to those of the ionic profile, changes from opposite phase in the alkalis to almost in-phase for Si.

Simultaneous determination of nikethamide and lidocaine in human blood and cerebrospinal fluid by high performance liquid chromatography.

PubMed

Chen, Lili; Liao, Linchuan; Zuo, Zhong; Yan, Youyi; Yang, Lin; Fu, Qiang; Chen, Yu; Hou, Junhong

2007-04-11

Nikethamide and lidocaine are often requested to be quantified simultaneously in forensic toxicological analysis. A simple reversed-phase high performance liquid chromatography (RP-HPLC) method has been developed for their simultaneous determination in human blood and cerebrospinal fluid. The method involves simple protein precipitation sample treatment followed by quantification of analytes using HPLC at 263 nm. Analytes were separated on a 5 microm Zorbax Dikema C18 column (150 mm x 4.60 mm, i.d.) with a mobile phase of 22:78 (v/v) mixture of methanol and a diethylamine-acetic acid buffer, pH 4.0. The mean recoveries were between 69.8 and 94.4% for nikethamide and between 78.9 and 97.2% for lidocaine. Limits of detection (LODs) for nikethamide and lidocaine were 0.008 and 0.16 microg/ml in plasma and 0.007 and 0.14 microg/ml in cerebrospinal fluid, respectively. The mean intra-assay and inter-assay coefficients of variation (CVs) for both analytes were less than 9.2 and 10.8%, respectively. The developed method was applied to blood sample analyses in eight forensic cases, where blood concentrations of lidocaine ranged from 0.68 to 34.4 microg/ml and nikethamide ranged from 1.25 to 106.8 microg/ml. In six cases cerebrospinal fluid analysis was requested. The values ranged from 20.3 to 185.6 microg/ml of lidocaine and 8.0 to 72.4 microg/ml of nikethamide. The method is simple and sensitive enough to be used in toxicological analysis for simultaneous determination of nikethamide and lidocaine in blood and cerebrospinal fluid.

Communication: Simple liquids' high-density viscosity

NASA Astrophysics Data System (ADS)

Costigliola, Lorenzo; Pedersen, Ulf R.; Heyes, David M.; Schrøder, Thomas B.; Dyre, Jeppe C.

2018-02-01

This paper argues that the viscosity of simple fluids at densities above that of the triple point is a specific function of temperature relative to the freezing temperature at the density in question. The proposed viscosity expression, which is arrived at in part by reference to the isomorph theory of systems with hidden scale invariance, describes computer simulations of the Lennard-Jones system as well as argon and methane experimental data and simulation results for an effective-pair-potential model of liquid sodium.

High-Performance Computing Data Center Warm-Water Liquid Cooling |

Science.gov Websites

Computational Science | NREL Warm-Water Liquid Cooling High-Performance Computing Data Center Warm-Water Liquid Cooling NREL's High-Performance Computing Data Center (HPC Data Center) is liquid water Liquid cooling technologies offer a more energy-efficient solution that also allows for effective

Determination of myriocin in natural and cultured Cordyceps cicadae using 9-fluorenylmethyl chloroformate derivatization and high-performance liquid chromatography with UV-detection.

PubMed

Yu, Jiawen; Xu, Hongjuan; Mo, Zhihong; Zhu, Huali; Mao, Xianbing

2009-07-01

A simple and sensitive reversed-phase liquid chromatographic method, based on the precolumn derivatization with 9-fluorenylmethyl chloroformate, was developed for the determination of myriocin. The derivatization reaction was performed in organic solvents of pyridine and tetrahydrofuran at 40 degrees C. Several factors influencing the derivative yield were investigated and optimized. The formed derivative was stable for more than 24 h at room temperature. The detection wavelength was 262 nm. The system offered the following analytical parameters: the limit of detection was 0.045 microg ml(-1), the linear correlation coefficient was 0.9963 and the linear range response was from 2.0 to 500.0 microg ml(-1). The precision of the method was <2.0%. As a preliminary application, the method has been successfully applied to the determination of myriocin in natural and cultured Cordyceps cicadae.

Aflatoxin B1 in eggs and chicken livers by dispersive liquid-liquid microextraction and HPLC.

PubMed

Amirkhizi, Behzad; Arefhosseini, Seyed Rafie; Ansarin, Masoud; Nemati, Mahboob

2015-01-01

A rapid, low-cost and simple technique has been developed for the determination of aflatoxin B1 (AFB1) in eggs and livers using high-performance liquid chromatography (HPLC) with UV detection. In this study, the presence of AFB1 was investigated in 150 eggs and 50 chicken livers from the local market of Tabriz, Iran. AFB1 was extracted with a mixture of acetonitrile:water (80:20) and cleaned up by dispersive liquid-liquid microextraction which is a very economical, fast and sensitive method. AFB1 was quantified by HPLC-UV without need for any complex derivatisation in samples to enhance the detection. The results showed that 72% of the liver and 58% of the egg samples were contaminated with AFB1 ranging from 0.30 to 16.36 µg kg (̶1). limit of detection and limit of quantification for AFB1 were 0.08 and 0.28 µg kg (̶ 1), respectively. The proposed method is suitable for fast analysing of AFB1 in egg and liver samples.

Centrifugeless dispersive liquid-liquid microextraction based on salting-out phenomenon followed by high performance liquid chromatography for determination of Sudan dyes in different species.

PubMed

Bazregar, Mohammad; Rajabi, Maryam; Yamini, Yadollah; Arghavani-Beydokhti, Somayeh; Asghari, Alireza

2018-04-01

In this work, a novel method, namely centrifugeless dispersive liquid-liquid microextraction, is introduced for the efficient extraction of banned Sudan dyes from foodstuff and water samples. In this method, which is based upon the salting-out phenomenon, in order to accelerate the extraction process, the extraction solvent (1-undecanol, 75 μL) is dispersed into the sample solution. Then the mixture is passed through a small column filled with 5 g sodium chloride, used as a separating reagent. In this condition, fine droplets of the extraction solvent are floated on the mixture, and the phase separation is simply achieved. This method is environmentally friendly, simple, and very fast, so that the overall extraction time is only 7 min. Under the optimal experimental conditions, the preconcentration factors in the range of 90-121 were obtained for the analytes. Also good linearities were obtained in the range of 2.5-1200 ng mL -1 (r 2  ≥ 0.993). Copyright © 2017 Elsevier Ltd. All rights reserved.

[Determination of vitamins D2, vitamin D3 in cosmetics by high performance liquid chromatography].

PubMed

Zhu, Ying; Yang, Yan-Wei; Wang, Xin

2005-09-01

A high performance liquid chromatography method was used to detect vitamins D2 and vitamin D3, which is useful to know the use of vitamins D2 and vitamin D3 in cosmetics, prohibit the influx of cosmetics containing vitamins D2 and vitamin D3 to cosmetic market, safeguard the health of consumers. A high performance liquid chromatography method was established for determination of vitamins D2 and vitamin D3 in cosmetics. The separation condition was optimized by trying different type of columns and mobile phases. The experiment goes on a Alltima C18 column (250 mm x 4.6 mm I. D., 5 microm)using methanol-acetonitrile (90: 10) as mobile phase at a flow rate of 1.0 ml/min, with the column temperature 25 degrees C and detection wave 265nm. The liner range is from 0.5 mg/L to 100 mg/L with good relationship. The detection limit of vitamin D2 is 0. 12 mg/L, the precision is less than 3.8% and recovery varies from 94.2% to 101.4%, while the detection limit of vitamin D3 is 0.06 mg/L, the precision is less than 3.5% and recovery varies from 91.6% to 97.2%. The method is simple, precise and accurate, which is suitable for the determination of vitamins D2 and vitamin D3 in cosmetics.

Simultaneous detection of six urinary pteridines and creatinine by high-performance liquid chromatography-tandem mass spectrometry for clinical breast cancer detection.

PubMed

Burton, Casey; Shi, Honglan; Ma, Yinfa

2013-11-19

Recent preliminary studies have implicated urinary pteridines as candidate biomarkers in a growing number of malignancies including breast cancer. While the developments of capillary electrophoresis-laser induced fluorescence (CE-LIF), high performance liquid chromatography (HPLC), and liquid chromatography-mass spectroscopy (LC-MS) pteridine urinalyses among others have helped to enable these findings, limitations including poor pteridine specificity, asynchronous or nonexistent renal dilution normalization, and a lack of information regarding adduct formation in mass spectrometry techniques utilizing electrospray ionization (ESI) have prevented application of these techniques to a larger clinical setting. In this study, a simple, rapid, specific, and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed and optimized for simultaneous detection of six pteridines previously implicated in breast cancer and creatinine as a renal dilution factor in urine. In addition, this study reports cationic adduct formation of urinary pteridines under ESI-positive ionization for the first time. This newly developed technique separates and detects the following six urinary pteridines: 6-biopterin, 6-hydroxymethylpterin, d-neopterin, pterin, isoxanthopterin, and xanthopterin, as well as creatinine. The method detection limit for the pteridines is between 0.025 and 0.5 μg/L, and for creatinine, it is 0.15 μg/L. The method was also validated by spiked recoveries (81-105%), reproducibility (RSD: 1-6%), and application to 25 real urine samples from breast cancer positive and negative samples through a double-blind study. The proposed technique was finally compared directly with a previously reported CE-LIF technique, concluding that additional or alternative renal dilution factors are needed for proper investigation of urinary pteridines as breast cancer biomarkers.

Simple determination of L-hydroxyproline in idiopathic pulmonary fibrosis lung tissues of rats using non-extractive high-performance liquid chromatography coupled with fluorescence detection after pre-column derivatization with novel synthetic 9-acetylimidazol-carbazole.

PubMed

Ren, Yan; Zhao, Juanjuan; Shi, Yanan; Chen, Caiyun; Chen, Xiangming; Lv, Changjun

2017-08-05

L-Hydroxyproline (L-Hyp) is an important biomarker for idiopathic pulmonary fibrosis (IPF). The quantitative methods based on high-performance liquid chromatography coupled with fluorescence detection after pre-column derivatization typically requires complicated derivatization conditions and obtains unstable derivatives. Here, a novel derivatization reagent, 9-acetylimidazol-carbazole, was synthesized for the first time to efficiently and rapidly label the amino groups of L-Hyp. The high-performance liquid chromatography method with pre-column derivatization was performed on an Agilent ZORBAX SB-C 18 column (4.6×250mm, 5μm). The product was measured using fluorescence detection at excitation and emission wavelengths of 232 and 370nm, respectively. The method was validated in specificity, linearity, limit of detection (66.7 fmol), limit of quantification (333.3fmol), intra-day precision (0.75%), inter-day precision (3.82%), stability (3.15%), and recovery (90.7-109.4%). The validated method was successfully applied to the determination of L-Hyp in the lung tissues of healthy and IPF rats. The results showed that the concentration of L-Hyp (3.64mg/g) in the IPF model was significantly higher than the concentration (2.33mg/g) in the healthy control group with P<0.01. This is a new method for the determination of L-Hyp and can be used for other amino acid-related studies in the future. Copyright © 2017. Published by Elsevier B.V.

Three-dimensional Imaging for Large LArTPCs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, C.; Qian, X.; Viren, B.

2017-12-14

High-performance event reconstruction is critical for current and future massive liquid argon time projection chambers (LArTPCs) to realize their full scientic potential. LArTPCs with readout using wire planes provides a limited number of 2D projections. In general, without a pixel-type readout it is challenging to achieve unambiguous 3D event reconstruction. As a remedy, we present a novel 3D imaging method, Wire-Cell, which incorporates the charge and sparsity information in addition to the time and geometry through simple and robust mathematics.

HPLC, MS, and pharmacokinetics of melphalan, bisantrene and 13-cis retinoic acid.

PubMed

Davis, T P; Peng, Y M; Goodman, G E; Alberts, D S

1982-11-01

High performance liquid chromatographic procedures are described for melphalan, bisantrene, and 13-cis retinoic acid, three important anticancer drugs in various stages of clinical development. The procedures require a rapid and simple sample clean-up followed by a 10-to 20-min chromatographic separation on a reversed-phase C18 column. Precisions are all less than 8% with recoveries greater than 80%. Mass spectrometry confirmation of each drug from patient sample separations is presented to provide unambiguous identification for valid pharmacokinetic parameter determination.

A parallel interaction potential approach coupled with the immersed boundary method for fully resolved simulations of deformable interfaces and membranes

NASA Astrophysics Data System (ADS)

Spandan, Vamsi; Meschini, Valentina; Ostilla-Mónico, Rodolfo; Lohse, Detlef; Querzoli, Giorgio; de Tullio, Marco D.; Verzicco, Roberto

2017-11-01

In this paper we show and discuss how the deformation dynamics of closed liquid-liquid interfaces (for example drops and bubbles) can be replicated with use of a phenomenological interaction potential model. This new approach to simulate liquid-liquid interfaces is based on the fundamental principle of minimum potential energy where the total potential energy depends on the extent of deformation of a spring network distributed on the surface of the immersed drop or bubble. Simulating liquid-liquid interfaces using this model require computing ad-hoc elastic constants which is done through a reverse-engineered approach. The results from our simulations agree very well with previous studies on the deformation of drops in standard flow configurations such as a deforming drop in a shear flow or cross flow. The interaction potential model is highly versatile, computationally efficient and can be easily incorporated into generic single phase fluid solvers to also simulate complex fluid-structure interaction problems. This is shown by simulating flow in the left ventricle of the heart with mechanical and natural mitral valves where the imposed flow, motion of ventricle and valves dynamically govern the behaviour of each other. Results from these simulations are compared with ad-hoc in-house experimental measurements. Finally, we present a simple and easy to implement parallelisation scheme, as high performance computing is unavoidable when studying large scale problems involving several thousands of simultaneously deforming bodies in highly turbulent flows.

The indicating FTA elute cartridge a solid sample carrier to detect high-risk HPV and high-grade cervical lesions.

PubMed

de Bie, Roosmarie P; Schmeink, Channa E; Bakkers, Judith M J E; Snijders, Peter J F; Quint, Wim G V; Massuger, Leon F A G; Bekkers, Ruud L M; Melchers, Willem J G

2011-07-01

The clinically validated high-risk human papillomavirus (hrHPV) Hybrid Capture 2 (HC2) and GP5+/6+-PCR assays were analyzed on an Indicating FTA Elute cartridge (FTA cartridge). The FTA cartridge is a solid dry carrier that allows safe transport of cervical samples. FTA cartridge samples were compared with liquid-based samples for hrHPV and high-grade cervical intraepithelial neoplasia (CIN) detection. One cervical sample was collected in a liquid-based medium, and one was applied to the FTA cartridge. DNA was eluted directly from the FTA cartridge by a simple elution step. HC2 and GP5+/6+-PCR assays were performed on both the liquid-based and the FTA-eluted DNA of 88 women. Overall agreement between FTA and liquid-based samples for the presence of hrHPV was 90.9% with GP5+/6+-PCR and 77.3% with HC2. The sensitivity for high-grade CIN of hrHPV testing on the FTA cartridges was 84.6% with GP5+/6+-PCR and only 53.8% with HC2. By comparison, these sensitivities on liquid-based samples were 92.3% and 100% for GP5+/6+-PCR and HC2, respectively. Therefore, the FTA cartridge shows reasonably good overall agreement for hrHPV detection with liquid-based media when using GP5+/6+-PCR but not HC2 testing. Even with GP5+/6+-PCR, the FTA cartridge is not yet capable of detecting all high-grade CIN lesions. Copyright © 2011 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.

A novel high sensitivity HPLC assay for topiramate, using 4-chloro-7-nitrobenzofurazan as pre-column fluorescence derivatizing agent.

PubMed

Bahrami, Gholamreza; Mohammadi, Bahareh

2007-05-01

A new, sensitive and simple high-performance liquid chromatographic method for analysis of topiramate, an antiepileptic agent, using 4-chloro-7-nitrobenzofurazan as pre-column derivatization agent is described. Following liquid-liquid extraction of topiramate and an internal standard (amlodipine) from human serum, derivatization of the drugs was performed by the labeling agent in the presence of dichloromethane, methanol, acetonitrile and borate buffer (0.05 M; pH 10.6). A mixture of sodium phosphate buffer (0.05 M; pH 2.4): methanol (35:65 v/v) was eluted as mobile phase and chromatographic separation was achieved using a Shimpack CLC-C18 (150 x 4.6 mm) column. In this method the limit of quantification of 0.01 microg/mL was obtained and the procedure was validated over the concentration range of 0.01 to 12.8 microg/mL. No interferences were found from commonly co-administrated antiepileptic drugs including phenytoin, phenobarbital carbamazepine, lamotrigine, zonisamide, primidone, gabapentin, vigabatrin, and ethosuximide. The analysis performance was carried-out in terms of specificity, sensitivity, linearity, precision, accuracy and stability and the method was shown to be accurate, with intra-day and inter-day accuracy from -3.4 to 10% and precise, with intra-day and inter-day precision from 1.1 to 18%.

Feasibility of the determination of polycyclic aromatic hydrocarbons in edible oils via unfolded partial least-squares/residual bilinearization and parallel factor analysis of fluorescence excitation emission matrices.

PubMed

Alarcón, Francis; Báez, María E; Bravo, Manuel; Richter, Pablo; Escandar, Graciela M; Olivieri, Alejandro C; Fuentes, Edwar

2013-01-15

The possibility of simultaneously determining seven concerned heavy polycyclic aromatic hydrocarbons (PAHs) of the US-EPA priority pollutant list, in extra virgin olive and sunflower oils was examined using unfolded partial least-squares with residual bilinearization (U-PLS/RBL) and parallel factor analysis (PARAFAC). Both of these methods were applied to fluorescence excitation emission matrices. The compounds studied were benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene and indeno[1,2,3-c,d]-pyrene. The analysis was performed using fluorescence spectroscopy after a microwave assisted liquid-liquid extraction and solid-phase extraction on silica. The U-PLS/RBL algorithm exhibited the best performance for resolving the heavy PAH mixture in the presence of both the highly complex oil matrix and other unpredicted PAHs of the US-EPA list. The obtained limit of detection for the proposed method ranged from 0.07 to 2 μg kg(-1). The predicted U-PLS/RBL concentrations were satisfactorily compared with those obtained using high-performance liquid chromatography with fluorescence detection. A simple analysis with a considerable reduction in time and solvent consumption in comparison with chromatography are the principal advantages of the proposed method. Copyright © 2012 Elsevier B.V. All rights reserved.

Liquid density analysis of sucrose and alcoholic beverages using polyimide guided Love-mode acoustic wave sensors

NASA Astrophysics Data System (ADS)

Turton, Andrew; Bhattacharyya, Debabrata; Wood, David

2006-02-01

A liquid density sensor using Love-mode acoustic waves has been developed which is suitable for use in the food and drinks industries. The sensor has an open flat surface allowing immersion into a sample and simple cleaning. A polyimide waveguide layer allows cheap and simple fabrication combined with a robust chemically resistant surface. The low shear modulus of polyimide allows thin guiding layers giving a high sensitivity. A dual structure with a smooth reference device exhibiting viscous coupling with the wave, and a patterned sense area to trap the liquid causing mass loading, allows discrimination of the liquid density from the square root of the density-viscosity product (ρη)0.5. Frequency shift and insertion loss change were proportional to (ρη)0.5 with a non-linear response due to the non-Newtonian nature of viscous liquids at high frequencies. Measurements were made with sucrose solutions up to 50% and different alcoholic drinks. A maximum sensitivity of 0.13 µg cm-3 Hz-1 was achieved, with a linear frequency response to density. This is the highest liquid density sensitivity obtained for acoustic mode sensors to the best of our knowledge.

Simultaneous Determination of Fluoroquinolones and Sulfonamides Originating from Sewage Sludge Compost

PubMed Central

Herodes, K.

2017-01-01

A simultaneous method for quantitative determination of traces of fluoroquinolones (FQs) and sulfonamides (SAs) in edible plants fertilized with sewage sludge was developed. The compounds were extracted from the plants by rapid and simple liquid extraction followed by extracts clean-up using solid phase extraction. The eluent additive 1,1,1,3,3,3-hexafluoro-2-propanol was used for liquid chromatographic detection to achieve separation of structurally similar antimicrobials like ciprofloxacin and norfloxacin. Identification and quantification of the compounds were performed using high-performance liquid chromatography with electrospray ionization mass spectrometry in selected reaction monitoring mode. Method was validated and extraction recoveries of FQs and SAs ranged from 66% to 93%. The limit of quantifications was from 5 ng/g in the case of ofloxacin to 40 ng/g for norfloxacin. The method precision ranged from 1.43% to 2.61%. The developed novel method was used to evaluate the plats antimicrobial uptake (potato (Solanum tuberosum L.), carrot (Daucus carota L.), lettuce (Lactuca sativa L.), and wheat (Triticum vulgare L.)) from soil and migration of the analytes inside the plants. PMID:28695191

Promising Cell Configuration for Next-Generation Energy Storage: Li2S/Graphite Battery Enabled by a Solvate Ionic Liquid Electrolyte.

PubMed

Li, Zhe; Zhang, Shiguo; Terada, Shoshi; Ma, Xiaofeng; Ikeda, Kohei; Kamei, Yutaro; Zhang, Ce; Dokko, Kaoru; Watanabe, Masayoshi

2016-06-29

Lithium-ion sulfur batteries with a [graphite|solvate ionic liquid electrolyte|lithium sulfide (Li2S)] structure are developed to realize high performance batteries without the issue of lithium anode. Li2S has recently emerged as a promising cathode material, due to its high theoretical specific capacity of 1166 mAh/g and its great potential in the development of lithium-ion sulfur batteries with a lithium-free anode such as graphite. Unfortunately, the electrochemical Li(+) intercalation/deintercalation in graphite is highly electrolyte-selective: whereas the process works well in the carbonate electrolytes inherited from Li-ion batteries, it cannot take place in the ether electrolytes commonly used for Li-S batteries, because the cointercalation of the solvent destroys the crystalline structure of graphite. Thus, only very few studies have focused on graphite-based Li-S full cells. In this work, simple graphite-based Li-S full cells were fabricated employing electrolytes beyond the conventional carbonates, in combination with highly loaded Li2S/graphene composite cathodes (Li2S loading: 2.2 mg/cm(2)). In particular, solvate ionic liquids can act as a single-phase electrolyte simultaneously compatible with both the Li2S cathode and the graphite anode and can further improve the battery performance by suppressing the shuttle effect. Consequently, these lithium-ion sulfur batteries show a stable and reversible charge-discharge behavior, along with a very high Coulombic efficiency.

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%.

A Compact Microwave Microfluidic Sensor Using a Re-Entrant Cavity.

PubMed

Hamzah, Hayder; Abduljabar, Ali; Lees, Jonathan; Porch, Adrian

2018-03-19

A miniaturized 2.4 GHz re-entrant cavity has been designed, manufactured and tested as a sensor for microfluidic compositional analysis. It has been fully evaluated experimentally with water and common solvents, namely methanol, ethanol, and chloroform, with excellent agreement with the expected behaviour predicted by the Debye model. The sensor's performance has also been assessed for analysis of segmented flow using water and oil. The samples' interaction with the electric field in the gap region has been maximized by aligning the sample tube parallel to the electric field in this region, and the small width of the gap (typically 1 mm) result in a highly localised complex permittivity measurement. The re-entrant cavity has simple mechanical geometry, small size, high quality factor, and due to the high concentration of electric field in the gap region, a very small mode volume. These factors combine to result in a highly sensitive, compact sensor for both pure liquids and liquid mixtures in capillary or microfluidic environments.

Teaching Simulation and Computer-Aided Separation Optimization in Liquid Chromatography by Means of Illustrative Microsoft Excel Spreadsheets

ERIC Educational Resources Information Center

Fasoula, S.; Nikitas, P.; Pappa-Louisi, A.

2017-01-01

A series of Microsoft Excel spreadsheets were developed to simulate the process of separation optimization under isocratic and simple gradient conditions. The optimization procedure is performed in a stepwise fashion using simple macros for an automatic application of this approach. The proposed optimization approach involves modeling of the peak…

Doping control analysis of 46 polar drugs in horse plasma and urine using a 'dilute-and-shoot' ultra high performance liquid chromatography-high resolution mass spectrometry approach.

PubMed

Kwok, Wai Him; Choi, Timmy L S; Kwok, Karen Y; Chan, George H M; Wong, Jenny K Y; Wan, Terence S M

2016-06-17

The high sensitivity of ultra high performance liquid chromatography coupled with high resolution mass spectrometry (UHPLC-HRMS) allows the identification of many prohibited substances without pre-concentration, leading to the development of simple and fast 'dilute-and-shoot' methods for doping control for human and equine sports. While the detection of polar drugs in plasma and urine is difficult using liquid-liquid or solid-phase extraction as these substances are poorly extracted, the 'dilute-and-shoot' approach is plausible. This paper describes a 'dilute-and-shoot' UHPLC-HRMS screening method to detect 46 polar drugs in equine urine and plasma, including some angiotensin-converting enzyme (ACE) inhibitors, sympathomimetics, anti-epileptics, hemostatics, the new doping agent 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), as well as two threshold substances, namely dimethyl sulfoxide and theobromine. For plasma, the sample (200μL) was protein precipitated using trichloroacetic acid, and the resulting supernatant was diluted using Buffer A with an overall dilution factor of 3. For urine, the sample (20μL) was simply diluted 50-fold with Buffer A. The diluted plasma or urine sample was then analysed using a UHPLC-HRMS system in full-scan ESI mode. The assay was validated for qualitative identification purpose. This straightforward and reliable approach carried out in combination with other screening procedures has increased the efficiency of doping control analysis in the laboratory. Moreover, since the UHPLC-HRMS data were acquired in full-scan mode, the method could theoretically accommodate an unlimited number of existing and new doping agents, and would allow a retrospectively search for drugs that have not been targeted at the time of analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Jetting from impact of a spherical drop with a deep layer

NASA Astrophysics Data System (ADS)

Zhang, Li; Toole, Jameson; Fazzaa, Kamel; Deegan, Robert; Deegan Group Team; X-Ray Science Division, Advanced Photon Source Collaboration

2011-11-01

We performed an experimental study of jets during the impact of a spherical drop with a deep layer of same liquid. Using high speed optical and X-ray imaging, we observe two types of jets: the so-called ejecta sheet which emerges almost immediately after impact and the lamella which emerges later. For high Reynolds number the two jets are distinct, while for low Reynolds number the two jets combine into a single continuous jet. We also measured the emergence time, speed, and position of the ejecta sheet and found simple scaling relations for these quantities.

Ionic liquid [OMIm][OAc] directly inducing oxidation cleavage of the β-O-4 bond of lignin model compounds.

PubMed

Yang, Yingying; Fan, Honglei; Meng, Qinglei; Zhang, Zhaofu; Yang, Guanying; Han, Buxing

2017-08-03

We explored the oxidation reactions of lignin model compounds directly induced by ionic liquids under metal-free conditions. In this work, it was found that ionic liquid 1-octyl-3-methylimidazolium acetate as a solvent could promote the aerobic oxidation of lignin model compound 2-phenoxyacetophenone (1) and the yields of phenol and benzoic acid from 1 could be as high as 96% and 86%, respectively. A possible reaction pathway was proposed based on a series of control experiments. An acetate anion from the ionic liquid attacked the hydrogen from the β-carbon thereby inducing the cleavage of the C-O bond of the aromatic ether. Furthermore, it was found that 2-(2-methoxyphenoxy)-1-phenylethanone (4) with a methoxyl group could also be transformed into aromatic products in this simple reaction system and the yields of phenol and benzoic acid from 4 could be as high as 98% and 85%, respectively. This work provides a simple way for efficient transformation of lignin model compounds.

Liquid oxygen liquid acquisition device bubble point tests with high pressure lox at elevated temperatures

NASA Astrophysics Data System (ADS)

Jurns, J. M.; Hartwig, J. W.

2012-04-01

When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth's gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMDs) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122 K) as part of NASA's continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures.

Development of an ionic liquid-based ultrasonic-assisted liquid-liquid microextraction method for sensitive determination of biogenic amines: application to the analysis of octopamine, tyramine and phenethylamine in beer samples.

PubMed

Huang, Ke-Jing; Jin, Chun-Xue; Song, Shi-Lin; Wei, Cai-Yun; Liu, Yan-Ming; Li, Jing

2011-03-15

A simple and efficient method, ionic liquid-based ultrasound-assisted liquid-liquid microextraction, has been developed for the determination of three biogenic amines including octopamine (OCT), tyramine (TYR) and phenethylamine (PHE). Fluorescence probe 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester was applied for derivatization of biogenic amines and high-performance liquid chromatography coupled with fluorescence detection was used for the determination of the derivatives. The factors affecting the extraction efficiency, such as the type and volume of ionic liquid, ultrasonication time and centrifugation time have been investigated in detail. Under the optimum conditions, linearity of the method was observed in the range of 0.5-50 μgmL(-1) for OCT and TYR, and 0.025-2.5 μgmL(-1) for PHE, respectively, with correlation coefficients (γ)>0.996. The limits of detection ranged from 0.25-50 ngmL(-1) (S/N=3). The spiked recoveries of three target compounds in beer samples were in the range of 90.2-114%. As a result, this method has been successfully applied for the sensitive determination of OCT, TYR and PHE in beer samples. Copyright © 2011 Elsevier B.V. All rights reserved.

Liquid Oxygen Liquid Acquisition Device Bubble Point Tests with High Pressure LOX at Elevated Temperatures

NASA Technical Reports Server (NTRS)

Jurns, John M.; Hartwig, Jason W.

2011-01-01

When transferring propellant in space, it is most efficient to transfer single phase liquid from a propellant tank to an engine. In earth s gravity field or under acceleration, propellant transfer is fairly simple. However, in low gravity, withdrawing single-phase fluid becomes a challenge. A variety of propellant management devices (PMD) are used to ensure single-phase flow. One type of PMD, a liquid acquisition device (LAD) takes advantage of capillary flow and surface tension to acquire liquid. The present work reports on testing with liquid oxygen (LOX) at elevated pressures (and thus temperatures) (maximum pressure 1724 kPa and maximum temperature 122K) as part of NASA s continuing cryogenic LAD development program. These tests evaluate LAD performance for LOX stored in higher pressure vessels that may be used in propellant systems using pressure fed engines. Test data shows a significant drop in LAD bubble point values at higher liquid temperatures, consistent with lower liquid surface tension at those temperatures. Test data also indicates that there are no first order effects of helium solubility in LOX on LAD bubble point prediction. Test results here extend the range of data for LOX fluid conditions, and provide insight into factors affecting predicting LAD bubble point pressures.

Comparison of green sample preparation techniques in the analysis of pyrethrins and pyrethroids in baby food by liquid chromatography-tandem mass spectrometry.

PubMed

Petrarca, Mateus Henrique; Ccanccapa-Cartagena, Alexander; Masiá, Ana; Godoy, Helena Teixeira; Picó, Yolanda

2017-05-12

A new selective and sensitive liquid chromatography triple quadrupole mass spectrometry method was developed for simultaneous analysis of natural pyrethrins and synthetic pyrethroids residues in baby food. In this study, two sample preparation methods based on ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and salting-out assisted liquid-liquid extraction (SALLE) were optimized, and then, compared regarding the performance criteria. Appropriate linearity in solvent and matrix-based calibrations, and suitable recoveries (75-120%) and precision (RSD values≤16%) were achieved for selected analytes by any of the sample preparation procedures. Both methods provided the analytical selectivity required for the monitoring of the insecticides in fruit-, cereal- and milk-based baby foods. SALLE, recognized by cost-effectiveness, and simple and fast execution, provided a lower enrichment factor, consequently, higher limits of quantification (LOQs) were obtained. Some of them too high to meet the strict legislation regarding baby food. Nonetheless, the combination of ultrasound and DLLME also resulted in a high sample throughput and environmental-friendly method, whose LOQs were lower than the default maximum residue limit (MRL) of 10μgkg -1 set by European Community for baby foods. In the commercial baby foods analyzed, cyhalothrin and etofenprox were detected in different samples, demonstrating the suitability of proposed method for baby food control. Copyright © 2017 Elsevier B.V. All rights reserved.

A comparative pharmacokinetic study of three flavonoids and three anthraquinones in normal and gastrointestinal motility disorders rat plasma after the oral administration of Wei-Chang-Shu tablet using high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Ren, Yan; Zhao, Weiwei; Zhao, Juanjuan; Chen, Xiangming; Yu, Chen; Liu, Mengan

2017-11-01

A simple, fast and reliable high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous quantification and pharmacokinetic study of three flavonoids (liquiritigenin, isoliquiritigenin and formononetin) and three anthraquinones (emodin, rhein and aloe-emodin), which are the bioactive ingredients of Wei-Chang-Shu tablet found in rat plasma. After extraction by liquid-liquid extraction with ethyl acetate, chromatographic separation was achieved on an Agilent Zorbax SB-C 18 column (4.6 × 150 mm, 5 μm) at a flow rate of 1 mL/min by gradient elution using 0.1% aqueous acetic acid and acetonitrile. The detection was performed using a triple quadrupole mass spectrometer equipped with electrospray ionization source in the negative ionization and selected reaction monitoring mode. Method validation was performed in terms of specificity, carryover, linearity (r > 0.99), intra-/inter-day precision (1.0-10.1%), accuracy (relative error, <7.6%), stability (0.6-13.2%), extract recovery (74.9-91.9%) and matrix effect (89.1-109%). The lower limits of quantification of the six analytes varied from 0.92 to 10.4 ng/mL. The validated method was successfully applied to compare the pharmacokinetic properties of Wei-Chang-Shu tablet in normal rats and in rats with gastrointestinal motility disorders. The results indicated that there were obvious differences in the pharmacokinetic behavior between normal and model rats. This study will be helpful in the clinical application of Wei-Chang-Shu tablet. Copyright © 2017 John Wiley & Sons, Ltd.

A simple and selective method for determination of phthalate biomarkers in vegetable samples by high pressure liquid chromatography-electrospray ionization-tandem mass spectrometry.

PubMed

Zhou, Xi; Cui, Kunyan; Zeng, Feng; Li, Shoucong; Zeng, Zunxiang

2016-06-01

In the present study, solid-phase extraction cartridges including silica reversed-phase Isolute C18, polymeric reversed-phase Oasis HLB and mixed-mode anion-exchange Oasis MAX, and liquid-liquid extractions with ethyl acetate, n-hexane, dichloromethane and its mixtures were compared for clean-up of phthalate monoesters from vegetable samples. Best recoveries and minimised matrix effects were achieved using ethyl acetate/n-hexane liquid-liquid extraction for these target compounds. A simple and selective method, based on sample preparation by ultrasonic extraction and liquid-liquid extraction clean-up, for the determination of phthalate monoesters in vegetable samples by liquid chromatography/electrospray ionisation-tandem mass spectrometry was developed. The method detection limits for phthalate monoesters ranged from 0.013 to 0.120 ng g(-1). Good linearity (r(2)>0.991) between MQLs and 1000× MQLs was achieved. The intra- and inter-day relative standard deviation values were less than 11.8%. The method was successfully used to determine phthalate monoester metabolites in the vegetable samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Determination of josamycin residues in porcine tissues using high-performance liquid chromatography with pre-column derivatization and spectrofluorimetric detection.

PubMed

Leroy, P; Decolin, D; Nicolas, A; Archimbault, P

1994-12-01

A simple, selective and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the measurement of josamycin residues in four porcine tissues (i.e., muscle, liver, kidney and fat). The sample preparation consisted of a homogenization step in an acetonitrile-10 mmol l-1 phosphate buffer mixture, pH 6.0 (35 + 65), centrifugation and a liquid-liquid extractive clean-up of the resulting supernatant with isooctane. Pre-column derivatization of josamycin was performed using cyclohexa-1,3-dione in ammonium acetate buffer, pH 5.0 (90 degrees C for 2 h). The derivative was chromatographed in an isocratic reversed-phase HPLC system. A LiChrospher RP 18 end-capped (5 microns) column was eluted with an acetonitrile-methanol-10 mmol l-1 phosphate buffer mixture, pH 6.0 (45 + 5 + 50). The capacity factor of the josamycin derivative was 17.5. Detection was achieved using spectrofluorimetry (lambda ex = 375 nm; lambda em = 450 nm). The structure of the derivative was assessed by using mass spectrometry. Full selectivity was obtained in the HPLC system versus other macrolide antibiotics (tylosin, spiramycin and erythromycin), aldehydes (formaldehyde, acetaldehyde and benzaldehyde) and endogenous compounds. Linearity and repeatability were tested. Correlation coefficients, for calibration curves in the range of 0.1-3.2 micrograms g-1, were greater than 0.999 for all tissues and the relative standard deviation (S(r)) was 4.9% (1.6 micrograms g-1; n = 6); recovery was higher than 88%.

Automated Gravimetric Calibration to Optimize the Accuracy and Precision of TECAN Freedom EVO Liquid Handler

PubMed Central

Bessemans, Laurent; Jully, Vanessa; de Raikem, Caroline; Albanese, Mathieu; Moniotte, Nicolas; Silversmet, Pascal; Lemoine, Dominique

2016-01-01

High-throughput screening technologies are increasingly integrated into the formulation development process of biopharmaceuticals. The performance of liquid handling systems is dependent on the ability to deliver accurate and precise volumes of specific reagents to ensure process quality. We have developed an automated gravimetric calibration procedure to adjust the accuracy and evaluate the precision of the TECAN Freedom EVO liquid handling system. Volumes from 3 to 900 µL using calibrated syringes and fixed tips were evaluated with various solutions, including aluminum hydroxide and phosphate adjuvants, β-casein, sucrose, sodium chloride, and phosphate-buffered saline. The methodology to set up liquid class pipetting parameters for each solution was to split the process in three steps: (1) screening of predefined liquid class, including different pipetting parameters; (2) adjustment of accuracy parameters based on a calibration curve; and (3) confirmation of the adjustment. The run of appropriate pipetting scripts, data acquisition, and reports until the creation of a new liquid class in EVOware was fully automated. The calibration and confirmation of the robotic system was simple, efficient, and precise and could accelerate data acquisition for a wide range of biopharmaceutical applications. PMID:26905719

Quantification of Soluble Sugars and Sugar Alcohols by LC-MS/MS.

PubMed

Feil, Regina; Lunn, John Edward

2018-01-01

Sugars are simple carbohydrates composed primarily of carbon, hydrogen, and oxygen. They play a central role in metabolism as sources of energy and as building blocks for synthesis of structural and nonstructural polymers. Many different techniques have been used to measure sugars, including refractometry, colorimetric and enzymatic assays, gas chromatography, high-performance liquid chromatography, and nuclear magnetic resonance spectroscopy. In this chapter we describe a method that combines an initial separation of sugars by high-performance anion-exchange chromatography (HPAEC) with detection and quantification by tandem mass spectrometry (MS/MS). This combination of techniques provides exquisite specificity, allowing measurement of a diverse range of high- and low-abundance sugars in biological samples. This method can also be used for isotopomer analysis in stable-isotope labeling experiments to measure metabolic fluxes.

About the Shape of the Melting Line as a Possible Precursor of a Liquid-Liquid Phase Transition

NASA Astrophysics Data System (ADS)

Imre, Attila R.; Rzoska, Sylwester J.

Several simple, non-mesogenic liquids can exists in two or more different liquid forms. When the liquid-liquid line, separating two liquid forms, meets the melting line, one can expect some kind of break on the melting line, caused by the different freezing/melting behaviour of the two liquid forms. Unfortunately recently several researchers are using this vein of thinking in reverse; seeing some irregularity on the melting line, they will expect a break and the appearance of a liquid-liquid line. In this short paper, we are going to show, that in the case of the high-pressure nitrogen studied recently by Mukherjee and Boehler, the high-pressure data can be easily described by a smooth, break-free function, the modified Simon-Glatzel equation. In this way, the break, suggested by them and consequently the suggested appearance of a new liquid phase of the nitrogen might be artefacts.

Easy monitoring of velocity fields in microfluidic devices using spatiotemporal image correlation spectroscopy.

PubMed

Travagliati, Marco; Girardo, Salvatore; Pisignano, Dario; Beltram, Fabio; Cecchini, Marco

2013-09-03

Spatiotemporal image correlation spectroscopy (STICS) is a simple and powerful technique, well established as a tool to probe protein dynamics in cells. Recently, its potential as a tool to map velocity fields in lab-on-a-chip systems was discussed. However, the lack of studies on its performance has prevented its use for microfluidics applications. Here, we systematically and quantitatively explore STICS microvelocimetry in microfluidic devices. We exploit a simple experimental setup, based on a standard bright-field inverted microscope (no fluorescence required) and a high-fps camera, and apply STICS to map liquid flow in polydimethylsiloxane (PDMS) microchannels. Our data demonstrates optimal 2D velocimetry up to 10 mm/s flow and spatial resolution down to 5 μm.

Mixed ion/electron-conductive protective soft nanomatter-based conformal surface modification of lithium-ion battery cathode materials

NASA Astrophysics Data System (ADS)

Park, Jang-Hoon; Kim, Ju-Myung; Lee, Chang Kee; Lee, Sang-Young

2014-10-01

Understanding and control of interfacial phenomena between electrode material and liquid electrolytes are of major scientific importance for boosting development of high-performance lithium ion batteries with reliable electrochemical/safety attributes. Here, as an innovative surface engineering approach to address the interfacial issues, a new concept of mixed ion/electron-conductive soft nanomatter-based conformal surface modification of the cathode material is presented. The soft nanomatter is comprised of an electron conductive carbonaceous (C) substance embedded in an ion conductive polyimide (PI) nanothin compliant film. In addition to its structural uniqueness, the newly proposed surface modification benefits from a simple fabrication process. The PI/carbon soft nanomatter is directly synthesized on LiCoO2 surface via one-pot thermal treatment of polyamic acid (=PI precursor) and sucrose (=carbon source) mixture, where the LiCoO2 powders are chosen as a model system to explore the feasibility of this surface engineering strategy. The resulting PI/carbon coating layer facilitates electronic conduction and also suppresses unwanted side reactions arising from the cathode material-liquid electrolyte interface. These synergistic coating effects of the multifunctional PI/carbon soft nanomatter significantly improve high-voltage cell performance and also mitigate interfacial exothermic reaction between cathode material and liquid electrolyte.

Liquid Propulsion: Propellant Feed System Design. Chapter 2.3.11

NASA Technical Reports Server (NTRS)

Cannon, James L.

2010-01-01

The propellant feed system of a liquid rocket engine determines how the propellants are delivered from the tanks to the thrust chamber. They are generally classified as either pressure fed or pump fed. The pressure-fed system is simple and relies on tank pressures to feed the propellants into the thrust chamber. This type of system is typically used for space propulsion applications and auxiliary propulsion applications requiring low system pressures and small quantities of propellants. In contrast, the pump-fed system is used for high pressure, high performance applications. The selection of one propellant feed system over another is determined based on design trade studies at both the engine and vehicle levels. This chapter first provides a brief overview of the basic configurations of pressure-fed systems. Pump-fed systems are then discussed with greater detail given to the turbomachinery design. Selected design requirements and configurations are provided.

Porous 3D graphene-based bulk materials with exceptional high surface area and excellent conductivity for supercapacitors

PubMed Central

Zhang, Long; Zhang, Fan; Yang, Xi; Long, Guankui; Wu, Yingpeng; Zhang, Tengfei; Leng, Kai; Huang, Yi; Ma, Yanfeng; Yu, Ao; Chen, Yongsheng

2013-01-01

Until now, few sp2 carbon materials simultaneously exhibit superior performance for specific surface area (SSA) and electrical conductivity at bulk state. Thus, it is extremely important to make such materials at bulk scale with those two outstanding properties combined together. Here, we present a simple and green but very efficient approach using two standard and simple industry steps to make such three-dimensional graphene-based porous materials at the bulk scale, with ultrahigh SSA (3523 m2/g) and excellent bulk conductivity. We conclude that these materials consist of mainly defected/wrinkled single layer graphene sheets in the dimensional size of a few nanometers, with at least some covalent bond between each other. The outstanding properties of these materials are demonstrated by their superior supercapacitor performance in ionic liquid with specific capacitance and energy density of 231 F/g and 98 Wh/kg, respectively, so far the best reported capacitance performance for all bulk carbon materials. PMID:23474952

HOT ELUENT CAPILLARY LIQUID CHROMATOGRAPHY USING ZIRCONIA AND TITANIA BASED STATIONARY PHASES. (R825344)

EPA Science Inventory

Abstract

High speed capillary liquid chromatographic separations using a simple home made system constructed from readily available inexpensive components have been studied. Using thermally stable zirconia and titania based packing, the separation of eight alkylbenzene...

Simple method for determination of patulin production by Penicillium griseofulvum Dierckx.

PubMed Central

Torres, M; Sanchis, V; Riba, M; Canela, R

1986-01-01

Patulin production by Penicillium griseofulvum was monitored with Sep-Pak cartridges and high-pressure liquid chromatography. Determination and quantification of this metabolite proved to be very simple, and our method saved time and a large amount of organic solvents. PMID:3513700

Simultaneous determination of 13 carotenoids by a simple C18 column-based ultra-high-pressure liquid chromatography method for carotenoid profiling in the astaxanthin-accumulating Haematococcus pluvialis.

PubMed

Jin, Hui; Lao, Yong Min; Zhou, Jin; Zhang, Huai Jin; Cai, Zhong Hua

2017-03-10

A simple ultra-high-pressure liquid chromatography (UHPLC) method for rapidly and simultaneously identifying thirteen carotenoids in Haematococcus pluvialis was developed in this study. The method is capable of effectively separating two astaxanthin isomers, two ζ-carotene isomers, and three phytoene isomers on two simple C18 columns within 9 and 12min only by using methanol and acetonitrile, respectively. To our best knowledge, this is the rapidest method for these carotenoid isomers, currently. Using this method, carotenoid profiling in the astaxanthin-accumulating H. pluvialis under environmental stresses was successfully carried out. Results indicated that carotenoid biosynthesis was differentially perturbed by environmental stresses, indicating that this simple and rapid method is suitable to not only bacterial but also algal samples, with potential applications for a wide range of samples from plant to animal. Finally, possible reasons for the elution order of carotenoids were studied. Copyright © 2017 Elsevier B.V. All rights reserved.

Magnetic solid-phase extraction of heterocyclic pesticides in environmental water samples using metal-organic frameworks coupled to high performance liquid chromatography determination.

PubMed

Ma, Jiping; Wu, Gege; Li, Shuang; Tan, Weiqiang; Wang, Xiaoyan; Li, Jinhua; Chen, Lingxin

2018-06-08

A simple method of magnetic solid-phase extraction (MSPE) coupled to high performance liquid chromatography (HPLC) was developed for the simultaneous extraction and determination of four kinds of heterocyclic pesticides (carbendazim, triadimefon, chlorfenapyr and fenpyroximate) in environmental water samples. Magnetic metal-organic frameworks (MOFs) of type MOF-5 were prepared and used as adsorbents of MSPE. Several main parameters influencing MSPE efficiency were investigated, including amount of magnetic MOF-5, sample solution pH, extraction time, salt concentration, type and volume of desorption solvents and desorption time. Under optimal conditions, the MSPE-HPLC method presented fast simple separation and analysis, and excellent linearity in the range of 0.3-500.0 μg/L for carbendazim and triadimefon, and 0.1-500.0 μg/L for chlorfenapyr and fenpyroximate, with correlation coefficients (r) higher than 0.9992. High sensitivity with limits of detection and quantification ranging from 0.04-0.11 μg/L and 0.13-0.35 μg/L, respectively, were achieved, as well as good precision with relative standard deviations of 2.98-7.11% (intra-day) and 3.31-7.12% (inter-day). Furthermore, the method was successfully applied to reservoir and Yellow River water samples, and satisfactory recoveries at three spiked concentration levels were between 80.20% and 108.33%.The magnetic MOF-5 composites based MSPE followed by HPLC proved promising for convenient and efficient determination of heterocyclic pesticides in environmental water samples. Copyright © 2018 Elsevier B.V. All rights reserved.

Fast quantification of endogenous carbohydrates in plasma using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry.

PubMed

Zhu, Bangjie; Liu, Feng; Li, Xituo; Wang, Yan; Gu, Xue; Dai, Jieyu; Wang, Guiming; Cheng, Yu; Yan, Chao

2015-01-01

Endogenous carbohydrates in biosamples are frequently highlighted as the most differential metabolites in many metabolomics studies. A simple, fast, simultaneous quantitative method for 16 endogenous carbohydrates in plasma has been developed using hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry. In order to quantify 16 endogenous carbohydrates in plasma, various conditions, including columns, chromatographic conditions, mass spectrometry conditions, and plasma preparation methods, were investigated. Different conditions in this quantified analysis were performed and optimized. The reproducibility, precision, recovery, matrix effect, and stability of the method were verified. The results indicated that a methanol/acetonitrile (50:50, v/v) mixture could effectively and reproducibly precipitate rat plasma proteins. Cold organic solvents coupled with vortex for 1 min and incubated at -20°C for 20 min were the most optimal conditions for protein precipitation and extraction. The results, according to the linearity, recovery, precision, matrix effect, and stability, showed that the method was satisfactory in the quantification of endogenous carbohydrates in rat plasma. The quantified analysis of endogenous carbohydrates in rat plasma performed excellently in terms of sensitivity, high throughput, and simple sample preparation, which met the requirement of quantification in specific expanded metabolomic studies after the global metabolic profiling research. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High-throughput method for macrolides and lincosamides antibiotics residues analysis in milk and muscle using a simple liquid-liquid extraction technique and liquid chromatography-electrospray-tandem mass spectrometry analysis (LC-MS/MS).

PubMed

Jank, Louise; Martins, Magda Targa; Arsand, Juliana Bazzan; Campos Motta, Tanara Magalhães; Hoff, Rodrigo Barcellos; Barreto, Fabiano; Pizzolato, Tânia Mara

2015-11-01

A fast and simple method for residue analysis of the antibiotics classes of macrolides (erythromycin, azithromycin, tylosin, tilmicosin and spiramycin) and lincosamides (lincomycin and clindamycin) was developed and validated for cattle, swine and chicken muscle and for bovine milk. Sample preparation consists in a liquid-liquid extraction (LLE) with acetonitrile, followed by liquid chromatography-electrospray-tandem mass spectrometry analysis (LC-ESI-MS/MS), without the need of any additional clean-up steps. Chromatographic separation was achieved using a C18 column and a mobile phase composed by acidified acetonitrile and water. The method was fully validated according the criteria of the Commission Decision 2002/657/EC. Validation parameters such as limit of detection, limit of quantification, linearity, accuracy, repeatability, specificity, reproducibility, decision limit (CCα) and detection capability (CCβ) were evaluated. All calculated values met the established criteria. Reproducibility values, expressed as coefficient of variation, were all lower than 19.1%. Recoveries range from 60% to 107%. Limits of detection were from 5 to 25 µg kg(-1).The present method is able to be applied in routine analysis, with adequate time of analysis, low cost and a simple sample preparation protocol. Copyright © 2015. Published by Elsevier B.V.

Multiple monolithic fiber solid-phase microextraction based on a polymeric ionic liquid with high-performance liquid chromatography for the determination of steroid sex hormones in water and urine.

PubMed

Liao, Keren; Mei, Meng; Li, Haonan; Huang, Xiaojia; Wu, Cuiqin

2016-02-01

The development of a simple and sensitive analytical approach that combines multiple monolithic fiber solid-phase microextraction with liquid desorption followed by high-performance liquid chromatography with diode array detection is proposed for the determination of trace levels of seven steroid sex hormones (estriol, 17β-estradiol, testosterone, ethinylestradiol, estrone, progesterone and mestranol) in water and urine matrices. To extract the target analytes effectively, multiple monolithic fiber solid-phase microextraction based on a polymeric ionic liquid was used to concentrate hormones. Several key extraction parameters including desorption solvent, extraction and desorption time, pH value and ionic strength in sample matrix were investigated in detail. Under the optimal experimental conditions, the limits of detection were found to be in the range of 0.027-0.12 μg/L. The linear range was 0.10-200 μg/L for 17β-estradiol, 0.25-200 μg/L estriol, ethinylestradiol and estrone, and 0.50-200 μg/L for the other hormones. Satisfactory linearities were achieved for analytes with the correlation coefficients above 0.99. Acceptable method reproducibility was achieved by evaluating the repeatability and intermediate precision with relative standard deviations of both less than 8%. The enrichment factors ranged from 54- to 74-fold. Finally, the proposed method was successfully applied to the analysis of steroid sex hormones in environmental water samples and human urines with spiking recoveries ranged from 75.6 to 116%. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of superparamagnetic high-magnetization C18-functionalized magnetic silica nanoparticles as sorbents for enrichment and determination of methylprednisolone in rat plasma by high performance liquid chromatography.

PubMed

Yu, Panfeng; Wang, Qi; Zhang, Xifeng; Zhang, Xuesong; Shen, Shun; Wang, Yan

2010-09-23

In this study, a novel extraction and enrichment technique based on superparamagnetic high-magnetization C(18)-functionalized magnetic silica nanoparticles (C(18)-MNPs) as sorbents was successfully developed for the determination of methylprednisolone (MP) in rat plasma by high performance liquid chromatography (HPLC). The synthesized silica-coated magnetite modified with chlorodimethyl-n-octadecylsilane was about 320 nm in diameter with strong magnetism and high surface area. It provided an efficient way for extraction and concentration of MP in the samples through hydrophobic interaction by the interior C(18) groups. Moreover, MP adsorbed with C(18)-MNPs could be simply and rapidly isolated through placing a strong magnet on the bottom of container, and then easily eluted from C(18)-MNPs by n-hexane solution. Extraction conditions such as amounts of C(18)-MNPs added, adsorption time and desorption solvent, were investigated. Method validations including linear range, detection limit, precision, and recovery were also studied. The results showed that the proposed method based on C(18)-MNPs was a simple, accurate and high efficient approach for the analysis of MP in the complex plasma samples. Copyright © 2010 Elsevier B.V. All rights reserved.

A simple and efficient HPLC method for benznidazole dosage in human breast milk.

PubMed

Marson, María E; Padró, Juan M; Reta, Mario R; Altcheh, Jaime; García-Bournissen, Facundo; Mastrantonio, Guido

2013-08-01

Due to migration, Chagas disease is a significant public health problem in Latin America, and in other nonendemic regions. The 2 drugs currently available for the treatment, nifurtimox and benznidazole (BNZ), are associated with a high risk of toxicity in therapeutic doses. Excretion of drug into human breast milk is a potential source of unwanted exposure and pharmacologic effects in the nursing infant. However, this phenomenon was not evaluated until now, and measurement techniques for both drugs in milk were not developed. In this work, we described the development of a simple and fast method to quantify BNZ in human milk using a pretreatment that involves acid protein precipitation followed by tandem microfiltration, and reverse phase high-performance liquid chromatography/ultraviolet analysis. It is simple because it takes only 3 steps to obtain a clean extracted solution that is ready to inject into the high-performance liquid chromatography equipment. It is fast because a complete analysis of a sample takes only 36 minutes. Although the human breast milk composition is very variable, and lipids are one of the most difficult compounds to clean up on a milk sample, the procedure has proven to be robust and sensitive with a limit of detection of 0.3 μg/mL and quantization of 0.9 μg/mL. Despite a 70% recovery value, which could be considered a relatively low result, this recovery is reproducible (coefficient of variation <10%) and the analytical response under the linear range is very good (r = 0.9969 adjusted). Real samples of human breast milk from patients in treatment with BNZ were dosed to support the validation process of the method. The method described is fast, specific, accurate, precise, and sufficiently sensitive in the clinical context for the quantification of BNZ in human milk. For all these reasons, it is suitable for clinical risk evaluation studies.

Analytical Method Development and Validation for the Simultaneous Estimation of Abacavir and Lamivudine by Reversed-phase High-performance Liquid Chromatography in Bulk and Tablet Dosage Forms.

PubMed

Raees Ahmad, Sufiyan Ahmad; Patil, Lalit; Mohammed Usman, Mohammed Rageeb; Imran, Mohammad; Akhtar, Rashid

2018-01-01

A simple rapid, accurate, precise, and reproducible validated reverse phase high performance liquid chromatography (HPLC) method was developed for the determination of Abacavir (ABAC) and Lamivudine (LAMI) in bulk and tablet dosage forms. The quantification was carried out using Symmetry Premsil C18 (250 mm × 4.6 mm, 5 μm) column run in isocratic way using mobile phase comprising methanol: water (0.05% orthophosphoric acid with pH 3) 83:17 v/v and a detection wavelength of 245 nm and injection volume of 20 μl, with a flow rate of 1 ml/min. In the developed method, the retention times of ABAC and LAMI were found to be 3.5 min and 7.4 min, respectively. The method was validated in terms of linearity, precision, accuracy, limits of detection, limits of quantitation, and robustness in accordance with the International Conference on Harmonization guidelines. The assay of the proposed method was found to be 99% - 101%. The recovery studies were also carried out and mean % recovery was found to be 99% - 101%. The % relative standard deviation from reproducibility was found to be <2%. The proposed method was statistically evaluated and can be applied for routine quality control analysis of ABAC and LAMI in bulk and in tablet dosage form. Attempts were made to develop RP-HPLC method for simultaneous estimation of Abacavir and Lamivudine for the RP-HPLC method. The developed method was validated according to the ICH guidelines. The linearity, precision, range, robustness were within the limits as specified by the ICH guidelines. Hence the method was found to be simple, accurate, precise, economic and reproducible. So the proposed methods can be used for the routine quality control analysis of Abacavir and Lamivudine in bulk drug as well as in formulations. Abbreviations Used: HPLC: High-performance liquid chromatography, UV: Ultraviolet, ICH: International Conference on Harmonization, ABAC: Abacavir, LAMI: Lamivudine, HIV: Human immunodeficiency virus, AIDS: Acquired immunodeficiency syndrome, NRTI: Nucleoside reverse transcriptase inhibitors, ARV: Antiretroviral, RSD: Relative standard deviation, RT: Retention time, SD: Standard deviation.

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.

A simple, sensitive and rapid isocratic reversed-phase high-performance liquid chromatography method for determination and stability study of curcumin in pharmaceutical samples

PubMed Central

Amanolahi, Farjad; Mohammadi, Ali; Kazemi Oskuee, Reza; Nassirli, Hooriyeh; Malaekeh-Nikouei, Bizhan

2017-01-01

Objective: This study was designed to develop and validate a new reversed-phase high-performance liquid chromatography (RP-HPLC) method based on Q2 (R1) International Conference on Harmonization (ICH) guideline for determination of curcumin in pharmaceutical samples. Materials and Methods: The HPLC instrument method was optimized with isocratic elution with acetonitrile: ammonium acetate (45:55, v/v, pH 3.5), C18 column (150 mm×4.6 mm×5 µm particle size) and a flow rate of 1 ml/min in ambient condition and total retention time of 17 min. The volume of injection was set at 20 µl and detection was recorded at 425 nm. The robustness of the method was examined by changing the mobile phase composition, mobile phase pH, and flow rate. Results: The method was validated with respect to precision, accuracy and linearity in a concentration range of 2-100 µg/ml. The limit of detection (LOD) and limit of quantification (LOQ) were 0.25 and 0.5 µg/ml, respectively. The percentage of recovery was 98.9 to 100.5 with relative standard deviation (RSD) < 0.638%. Conclusion: The method was found to be simple, sensitive and rapid for determination of curcumin in pharmaceutical samples and had enough sensitivity to detect degradation product of curcumin produced under photolysis and hydrolysis stress condition. PMID:29062806

A simple high-performance liquid chromatographic method for the determination of acyclovir in human plasma and application to a pharmacokinetic study.

PubMed

Yu, Liyan; Xiang, Bingren; Zhan, Ying

2008-01-01

A rapid, simple and sensitive reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the measurement of acyclovir (CAS 59277-89-3) concentrations in human plasma and its use in bioavailability studies is evaluated. The method was linear in the concentration range of 0.05-4.0 microg/ml. The lower limit of quantification (LLOQ) was 0.05 microg/ml in 0.5 ml plasma sample. The intra- and inter-day relative standard deviations across three validation runs over the entire concentration range were less than 8.2%. This method was successfully applied for the evaluation of pharmacokinetic profiles of acyclovir capsule in 19 healthy volunteers. The main pharmacokinetic parameters obtained were: AUC(o-t) 6.50 +/- 1.47 and 7.13 +/- 1.44 microg x h/ml, AUC(0-infinity) 6.77 +/- 1.48 and 7.41 +/- 1.49 microg x h/ml, C(max) 2.27 +/- 0.57 and 2.27 +/- 0.62 microg/ml, t(1/2) 2.96 +/- 0.41 and 2.88 +/- 0.33 h, t(max) 0.8 +/- 0.3 and 1.0 +/- 0.5 h for test and reference formulations, respectively. No statistical differences were observed for C(max) and the area under the plasma concentration--time curve for acyclovir. 90% confidence limits calculated for C(max) and AUC from zero to infinity (AUC(0-infinity)) of acyclovir were included in the bioequivalence range (0.8-1.25 for AUC).

Efficient HPTLC-dual wavelength spectrodensitometric method for simultaneous determination of sofosbuvir and daclatasvir: Biological and pharmaceutical analysis.

PubMed

Abo-Zeid, Mohammad Nabil; El-Gizawy, Samia M; Atia, Noha N; El-Shaboury, Salwa R

2018-05-01

Sofosbuvir (SOF) and daclatasvir (DCS) are newly discovered anti-hepatitis C drugs that have direct antiviral activity. A novel and simple high-performance thin-layer chromatography (HPTLC) method was designed for simultaneous determination of SOF and DCS in miscellaneous matrices. The method adopts coupling HPTLC with dual wavelength spectrodensitometry. Consequently, this enabled sensitive, specific and cost-effective determination of the SOF-DCS mixture. The developed HPTLC procedure is based on a simple liquid-liquid extraction, enrichment of the analytes and subsequent chromatographic separation with UV detection. Separations were performed on HPTLC silica gel 60 F 254 aluminum plates with a mobile phase consisting of ethyl acetate-isopropanol (85:15, v/v). Dual wavelength scanning was carried out in the absorbance mode at 265 and 311 nm for SOF and DCS, respectively. The linear ranges were 40-640 and 20-320 ng band -1 for SOF and DCS, respectively with correlation coefficients of ≥0.9997. The detection limits were 11.3 and 6.5 ng band -1 for SOF and DCS, respectively indicating high sensitivity of the proposed method. Consequently, this permits in vitro and in vivo application of the proposed method in human plasma with good percentage recovery (94.1-103.5%). Validation parameters were assessed according to ICH guidelines and US-FDA guidelines. Furthermore, the application was extended to analysis of SOF and DCS in their pharmaceutical formulations. Copyright © 2018 Elsevier B.V. All rights reserved.

Simultaneous Determination of Six Benzodiazepines in Spiked Soft Drinks by High Performance Liquid Chromatography with Ultra Violet Detection (HPLC-UV)

PubMed Central

Soltaninejad, Kambiz; Karimi, Mohammad; Nateghi, Alireza; Daraei, Bahram

2016-01-01

A high performance liquid chromatographic method with ultra violet detection for simultaneous analysis of six benzodiazepines (BZDs) (chlordiazepoxide, diazepam, clonazepam, midazolam , flurazpam, and lorazepam) has been developed for forensic screening of adulterated non-alcoholic drinks. Samples were analyzed after a simple procedure for preparation using pH adjustment and filtering. Isocratic elution on a C18 column (250mm × 4.6 mm, 5μm) in the temperature 45ºC with a mobile phase consisting of 15mM phosphate buffer: methanol (50:50 v/v) at a flow rate 1.4 mL/min has been done. The column eluent was monitored with a UV detector at 245 nm. This allowed a rapid detection and identification as well as quantization of the eluting peaks. Calibration curves for all drugs in the range of 0.5- 10 µg/ mL that all the linear regression and has more than 0.996. Recovery rates for the BZDs were in the range 93.7- 108.7%. The limits of detection were calculated between 0.01- 0.02 µg/ mL. Also, the limits of quantification were 0.03- 0.05 µg/mL. Within-day and between -day coefficient of variation for all BZDs at all concentrations in the range of 0.45 - 7.69 % was calculated. The procedure can provide a simple, sensitive and fast method for the screening of six BZDs in adulterated soft drinks in forensic analysis. PMID:27642316

Passive Standoff Detection of Chemical Warfare Agents on Surfaces

NASA Astrophysics Data System (ADS)

Thériault, Jean-Marc; Puckrin, Eldon; Hancock, Jim; Lecavalier, Pierre; Lepage, Carmela Jackson; Jensen, James O.

2004-11-01

Results are presented on the passive standoff detection and identification of chemical warfare (CW) liquid agents on surfaces by the Fourier-transform IR radiometry. This study was performed during surface contamination trials at Defence Research and Development Canada-Suffield in September 2002. The goal was to verify that passive long-wave IR spectrometric sensors can potentially remotely detect surfaces contaminated with CW agents. The passive sensor, the Compact Atmospheric Sounding Interferometer, was used in the trial to obtain laboratory and field measurements of CW liquid agents, HD and VX. The agents were applied to high-reflectivity surfaces of aluminum, low-reflectivity surfaces of Mylar, and several other materials including an armored personnel carrier. The field measurements were obtained at a standoff distance of 60 m from the target surfaces. Results indicate that liquid contaminant agents deposited on high-reflectivity surfaces can be detected, identified, and possibly quantified with passive sensors. For low-reflectivity surfaces the presence of the contaminants can usually be detected; however, their identification based on simple correlations with the absorption spectrum of the pure contaminant is not possible.

Overview of online two-dimensional liquid chromatography based on cell membrane chromatography for screening target components from traditional Chinese medicines.

PubMed

Muhammad, Saqib; Han, Shengli; Xie, Xiaoyu; Wang, Sicen; Aziz, Muhammad Majid

2017-01-01

Cell membrane chromatography is a simple, specific, and time-saving technique for studying drug-receptor interactions, screening of active components from complex mixtures, and quality control of traditional Chinese medicines. However, the short column life, low sensitivity, low column efficiency (so cannot resolve satisfactorily mixture of compounds), low peak capacity, and inefficient in structure identification were bottleneck in its application. Combinations of cell membrane chromatography with multidimensional chromatography such as two-dimensional liquid chromatography and high sensitivity detectors like mass have significantly reduced many of the above-mentioned shortcomings. This paper provides an overview of the current advances in online two-dimensional-based cell membrane chromatography for screening target components from traditional Chinese medicines with particular emphasis on the instrumentation, preparation of cell membrane stationary phase, advantages, and disadvantages compared to alternative approaches. The last section of the review summarizes the applications of the online two-dimensional high-performance liquid chromatography based cell membrane chromatography reported since its emergence to date (2010-June 2016). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of acrylamide and methacrylamide by normal phase high performance liquid chromatography and UV detection.

PubMed

Paleologos, E K; Kontominas, M G

2005-06-10

A method using normal phase high performance liquid chromatography (NP-HPLC) with UV detection was developed for the analysis of acrylamide and methacrylamide. The method relies on the chromatographic separation of these analytes on a polar HPLC column designed for the separation of organic acids. Identification of acrylamide and methacrylamide is approached dually, that is directly in their protonated forms and as their hydrolysis products acrylic and methacrylic acid respectively, for confirmation. Detection and quantification is performed at 200 nm. The method is simple allowing for clear resolution of the target peaks from any interfering substances. Detection limits of 10 microg L(-1) were obtained for both analytes with the inter- and intra-day RSD for standard analysis lying below 1.0%. Use of acetonitrile in the elution solvent lowers detection limits and retention times, without impairing resolution of peaks. The method was applied for the determination of acrylamide and methacrylamide in spiked food samples without native acrylamide yielding recoveries between 95 and 103%. Finally, commercial samples of french and roasted fries, cookies, cocoa and coffee were analyzed to assess applicability of the method towards acrylamide, giving results similar with those reported in the literature.

Fingerprint chromatogram analysis of extracts from the leaves of Tripterygium wilfordii Hook. F. by high performance liquid chromatography.

PubMed

Li, Ke; Wang, Shudong

2005-05-01

A simple and reliable high performance liquid chromatographic (HPLC) method has been developed and validated for the study of fingerprint chromatograms of extracts from the leaves of Tripterygium wilfordii Hook. F. (TWHF) and for controlling the quality of the herb. HPLC separation of the extracts was performed on a Lichrospher RP-18 column and detected by ultraviolet absorbance at 210 nm. The column temperature was maintained at 35 degrees C. A mobile phase composed of acetonitrile:H2O in the ratio of 39:61 (v/v) was found to be most suitable for this separation at a flow rate of 0.8 mL/min with isocratic elution. Under the chromatographic conditions described, the peak profile of the 10 components collected within 35 min made up the fingerprint of the extracts from leaves of TWHF with universal features. The fingerprint chromatograms had a good stability, precision, and reproducibility. The similarity of the extracts from leaves of TWHF collected in summer and winter was studied with triptolide as a reference peak. The method is suitable for differentiation of extracts from the leaves of TWHF, and can be used as a quality control method for this herb.

[Simultaneous determination of canthaxanthin and astaxanthin in feedstuffs using solid phase extraction-reversed-phase high performance liquid chromatography].

PubMed

Zhang, Hua; Yang, Xin; Ma, Ying; Dong, Aijun; Zhang, Yingchun

2008-05-01

A method was developed for the simultaneous determination of canthaxanthin and astaxanthin in feedstuffs using reversed-phase high performance liquid chromatography (RP-HPLC). The sample was extracted by acetonitrile, and cleaned up by an LC-NH2 column. An Agilent ZORBAX Eclipse XDB-C18 analytical column (150 mm x 4.6 mm, 5 microm) was used and kept at 25 degrees C. Acetonitrile-methanol (95 : 5, v/v) was used as the mobile phase at a flow rate of 1.0 mL/min. The detection was performed by a diode array detector at 474 nm. The quantitive analysis of external standard calibration curves was used. The linear ranges of the method for canthaxanthin and astaxanthin were 1.0 - 30.0 mg/L (r = 0.999 0) and 1.0 - 20.0 mg/L (r = 0.999 1), respectively. The average recoveries were 90% - 101% with the relative standard deviations of 0.62% - 3.68%. The detection limits were 0.84 and 0.60 mg/L for canthaxanthin and astaxanthin, respectively. The method is simple, precise, sensitive and reproductive. It can be used to determine the contents of canthaxanthin and astaxanthin in feedstuffs.

[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.

Determination of starting materials, intermediates, and subsidiary colors in the color additive Food Red No. 106 (Sulforhodamine B) using high-performance liquid chromatography.

PubMed

Tatebe, Chiye; Ohtsuki, Takashi; Fujita, Tsuyoshi; Nishiyama, Koji; Itoh, Sumio; Sugimoto, Naoki; Kubota, Hiroki; Tada, Atsuko; Sato, Kyoko; Akiyama, Hiroshi

2017-12-15

The main subsidiary color of structure in Food Red No. 106 (R106) was identified to be a desethyl derivative (R106-SubA). High-performance liquid chromatography (HPLC) was performed for the quantitative determination of benzaldehyde-2,4-disulfonic acid, N,N-diethyl-m-aminophenol, leuco acid, pyrone acid, R106-SubA, etc. in R106. An ammonium acetate solution (20mM) and acetonitrile:water (7:3) were used to stabilize the retention time of the HPLC analytes. The linearity of the calibration curves was in the range of 0.05-10μg/mL, with good correlation coefficients (R 2 >0.9983). The recoveries of impurities at levels 0.1%, 0.5% and 1% ranged from 94.2% to 106.6% with relative standard deviations of 0.1%-1.0%. While surveying commercial R106, the amounts obtained by area% determination were similar to those obtained by the calibration-curve determination. The area% determination by HPLC for the determinations of impurities in R106 is a simple and reliable method and can be applied in routine analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stability of sotalol hydrochloride in extemporaneously prepared oral suspension formulations.

PubMed

Sidhom, Madiha B; Rivera, Nadya; Almoazen, Hassan; Taft, David R; Kirschenbaum, Harold L

2005-01-01

The physical, chemical, and microbial stabilities of extemporaneously compounded oral liquid formulations of sotalol hydrochloride were studied. Sotalol hydrochloride oral liquid suspensions (5mg/mL) were prepared from commercially available tablets (Betapace) in a 1:1 mixture of Ora-Plus: Ora-Sweet, a 1:1 mixture of Ora-Plus:Ora-Sweet SF, and a 1:2.4 mixture of simple syrup:methylcellulose vehicle. Six batches of each formulation were prepared; three were stored at refrigerated temperature (2 deg to 8 deg C) and three at room temperature (20 deg to 25 deg C). Samples were collected from each batch weekly for 6 weeks, and again at 12 weeks. Samples were analyzed by means of a high-performance liquid chromatographic method, and the concentrations obtained were compared to the theoretical time zero value. Samples were examined for pH, odor, color, and consistency changes. The suspensions also were evaluated for their microbial stability. Sotalol hydrochloride oral liquid suspensions (5mg/mL) were chemically stable for 12 weeks regardless of storage conditions (room temperature or refrigerated). Bacterial growth was not supported by any of the formulations. Suspensions stored at refrigerated temperature retained better physical quality (e.g., odor, color, and consistency) than suspensions stored at room temperature. Overall, this study demonstrates that oral formulations of sotalol hydrochloride can be readily prepared with commercially available vehicles. The method of preparation is relatively simple, the materials are relatively inexpensive, and the products have a shelf-life of at least 12 weeks.

Radhard optical patchcords and packaging for satellites using liquid crystal polymers

NASA Astrophysics Data System (ADS)

O'Riorden, S.; Mahapatra, A.

2017-11-01

There are many advantages to employing fiber optics for high capacity satellite communication. However, optical cables can be susceptible to high radiation, temperature extremes and vacuum environment. Any hardware used in these systems must be rugged, durable and immune to the detrimental effects of the aforementioned conditions. Standard COTS optical fiber will darken when exposed to high levels of radiation limiting the effectiveness of the communications system. Of particular concern to satellites in GEO are energetic electrons, bursts of heavy particles due to solar storms which can cause total dose and single event effects (SEE). Conventional fiber optic cables have several issues performing in high radiation environments. Linden has patented and developed a novel cable using an extruded layer of Liquid Crystal Polymer (LCP) applied to commercially available fiber. Total dose effects are minimized by shielding with Liquid Crystal Polymer jacketing. It is a simple, inexpensive way to increase the radiation shielding and mechanical performance of cables in satellites while concomitantly providing hermeticity and thus increased fatigue factor for optical glass. • LCPs exposed to 5000 Mrad dose of gamma rays retain in excess of 90% of their mechanical properties. • LCPs exposed to 1 Mrad radiation dose with energetic protons retain almost 100% of their mechanical strength. Tensile modulus increases with exposure to the radiation. • Weight for weight the proton absorbing power of LCP is 25% better than that of aluminum. We will present experimental data on radhard optical patchcords.

Genetic and Chemical Profiling of Gymnema sylvestre Accessions from Central India: Its Implication for Quality Control and Therapeutic Potential of Plant

PubMed Central

Verma, Ashutosh Kumar; Dhawan, Sunita Singh; Singh, Seema; Bharati, Kumar Avinash; Jyotsana

2016-01-01

Background: Gymnema sylvestre, a vulnerable plant species, is mentioned in Indian Pharmacopeia as an antidiabetic drug Objective: Study of genetic and chemical diversity and its implications in accessions of G. sylvestre Materials and Methods: Fourteen accessions of G. sylvestre collected from Central India and assessment of their genetic and chemical diversity were carried out using ISSR (inter simple sequence repeat) and HPLC (high performance liquid chromatography) fingerprinting methods Results: Among the screened 40 ISSR primers, 15 were found polymorphic and collectively produced nine unique accession-specific bands. The maximum and minimum numbers of amplicones were noted for ISSR-15 and ISSR-11, respectively. The ISSR -11 and ISSR-13 revealed 100% polymorphism. HPLC chromatograms showed that accessions possess the secondary metabolites of mid-polarity with considerable variability. Unknown peaks with retention time 2.63, 3.41, 23.83, 24.50, and 44.67 were found universal type. Comparative hierarchical clustering analysis based on foresaid fingerprints indicates that both techniques have equal potential to discriminate accessions according to percentage gymnemic acid in their leaf tissue. Second approach was noted more efficiently for separation of accessions according to their agro-climatic/collection site Conclusion: Highly polymorphic ISSRs could be utilized as molecular probes for further selection of high gymnemic acid yielding accessions. Observed accession specific bands may be used as a descriptor for plant accessions protection and converted into sequence tagged sites markers. Identified five universal type peaks could be helpful in identification of G. sylvestre-based various herbal preparations. SUMMARY Nine accession specific unique bandsFive marker peaks for G. sylvestre.Suitability of genetic and chemical fingerprinting Abbreviations used: HPLC: High Performance Liquid Chromatography, ISSR: Inter Simple Sequence Repeats, CTAB: Cetyl Trimethylammonium Bromide, DNTP: Deoxynucleotide Triphosphates PMID:27761067

Genetic and Chemical Profiling of Gymnema sylvestre Accessions from Central India: Its Implication for Quality Control and Therapeutic Potential of Plant.

PubMed

Verma, Ashutosh Kumar; Dhawan, Sunita Singh; Singh, Seema; Bharati, Kumar Avinash; Jyotsana

2016-07-01

Gymnema sylvestre , a vulnerable plant species, is mentioned in Indian Pharmacopeia as an antidiabetic drug. Study of genetic and chemical diversity and its implications in accessions of G. sylvestre . Fourteen accessions of G. sylvestre collected from Central India and assessment of their genetic and chemical diversity were carried out using ISSR (inter simple sequence repeat) and HPLC (high performance liquid chromatography) fingerprinting methods. Among the screened 40 ISSR primers, 15 were found polymorphic and collectively produced nine unique accession-specific bands. The maximum and minimum numbers of amplicones were noted for ISSR-15 and ISSR-11, respectively. The ISSR -11 and ISSR-13 revealed 100% polymorphism. HPLC chromatograms showed that accessions possess the secondary metabolites of mid-polarity with considerable variability. Unknown peaks with retention time 2.63, 3.41, 23.83, 24.50, and 44.67 were found universal type. Comparative hierarchical clustering analysis based on foresaid fingerprints indicates that both techniques have equal potential to discriminate accessions according to percentage gymnemic acid in their leaf tissue. Second approach was noted more efficiently for separation of accessions according to their agro-climatic/collection site. Highly polymorphic ISSRs could be utilized as molecular probes for further selection of high gymnemic acid yielding accessions. Observed accession specific bands may be used as a descriptor for plant accessions protection and converted into sequence tagged sites markers. Identified five universal type peaks could be helpful in identification of G. sylvestre -based various herbal preparations. Nine accession specific unique bandsFive marker peaks for G. sylvestre .Suitability of genetic and chemical fingerprinting Abbreviations used: HPLC: High Performance Liquid Chromatography, ISSR: Inter Simple Sequence Repeats, CTAB: Cetyl Trimethylammonium Bromide, DNTP: Deoxynucleotide Triphosphates.

High-performance liquid chromatographic analysis of vigabatrin enantiomers in human serum by precolumn derivatization with o-phthaldialdehyde-N-acetyl-L-cysteine and fluorescence detection.

PubMed

Vermeij, T A; Edelbroek, P M

1998-09-25

A rapid and simple method is presented for the determination of vigabatrin enantiomers in human serum by high-performance liquid chromatography. Serum is deproteinized with trichloroacetic acid and aliquots of the supernatant are precolumn derivatized with o-phthaldialdehyde and N-acetyl-L-cysteine, resulting in the formation of diastereomeric isoindoles. Separation was achieved on a Spherisorb 3ODS2 column using a gradient solvent program and the column eluent is monitored using fluorescence detection. L-Homoarginine was used as an internal standard. Within-day precisions (C.V.; n=8) were 2.8 and 1.1%, respectively, for the (R)-(-)- and (S)-(+)-enantiomer in serum containing 15.4 mg/l (RS)-vigabatrin. The method was linear in the 0-45 mg/l range for both enantiomers and the minimum quantitation limit was 0.20 mg/l for (R)-(-)-vigabatrin and 0.14 mg/l for (S)-(+)-vigabatrin. No interferences were found from commonly co-administered antiepileptic drugs and from endogenous amino acids. The method is suitable for routine therapeutic drug monitoring and for pharmacokinetic studies.

Optimization of sample preparation by central composite design for multi-class determination of veterinary drugs in bovine muscle, kidney and liver by ultra-high-performance liquid chromatographic-tandem mass spectrometry.

PubMed

Rizzetti, Tiele M; de Souza, Maiara P; Prestes, Osmar D; Adaime, Martha B; Zanella, Renato

2018-04-25

In this study a simple and fast multi-class method for the determination of veterinary drugs in bovine liver, kidney and muscle was developed. The method employed acetonitrile for extraction followed by clean-up with EMR-Lipid® sorbent and trichloracetic acid. Tests indicated that the use of TCA was most effective when added in the final step of the clean-up procedure instead of during extraction. Different sorbents were tested and optimized using central composite design and the analytes determined by ultra-high-performance liquid chromatographic-tandem mass spectrometry (UHPLC-MS/MS). The method was validated according the European Commission Decision 2002/657 presenting satisfactory results for 69 veterinary drugs in bovine liver and 68 compounds in bovine muscle and kidney. The method was applied in real samples and in proficiency tests and proved to be adequate for routine analysis. Residues of abamectin, doramectin, eprinomectin and ivermectin were found in samples of bovine muscle and only ivermectin in bovine liver. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination of triterpene glycosides in sea cucumber (Stichopus japonicus) and its related products by high-performance liquid chromatography.

PubMed

Dong, Ping; Xue, Chang-Hu; Yu, Lin-Fang; Xu, Jie; Chen, Shi-Guo

2008-07-09

A creative and sensitive method has been developed for the determination of triterpene glycosides concentrations in sea cucumber ( Stichopus japonicus) and related products by using d-quinovose (6-deoxyglucose) as the measurement standard by reverse-phase high-performance liquid chromatography (HPLC) and variable-wavelength detection. d-quinovose, which is a unique monosaccharide in holostane triterpene glycosides, was liberated by acid hydrolysis and precolumn derivatized by 1-phenyl-3-methyl-5-pyrazolone (PMP). PMP-quinovose was analyzed by HPLC with 22% acetonitrile in 0.05 M KH2PO4 aquatic solution (pH 5.2) as mobile phase. The calibration curves of d-quinovose were linear within the range of 6.56-164 mg/L (r(2) > 0.995). The contents of triterpene glycosides in various S. japonicus products were determined after appropriate pretreatment methods. The concentration of triterpene glycosides was calculated by the formula C = C(qui) x alpha (alpha = 8.5). The result showed that this method was a simple, rapid, and stable method for the determination of triterpene glycosides in S. japonicus products.

[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.

Application of mixed cloud point extraction for the analysis of six flavonoids in Apocynum venetum leaf samples by high performance liquid chromatography.

PubMed

Zhou, Jun; Sun, Jiang Bing; Xu, Xin Yu; Cheng, Zhao Hui; Zeng, Ping; Wang, Feng Qiao; Zhang, Qiong

2015-03-25

A simple, inexpensive and efficient method based on the mixed cloud point extraction (MCPE) combined with high performance liquid chromatography was developed for the simultaneous separation and determination of six flavonoids (rutin, hyperoside, quercetin-3-O-sophoroside, isoquercitrin, astragalin and quercetin) in Apocynum venetum leaf samples. The non-ionic surfactant Genapol X-080 and cetyl-trimethyl ammonium bromide (CTAB) was chosen as the mixed extracting solvent. Parameters that affect the MCPE processes, such as the content of Genapol X-080 and CTAB, pH, salt content, extraction temperature and time were investigated and optimized. Under the optimized conditions, the calibration curve for six flavonoids were all linear with the correlation coefficients greater than 0.9994. The intra-day and inter-day precision (RSD) were below 8.1% and the limits of detection (LOD) for the six flavonoids were 1.2-5.0 ng mL(-1) (S/N=3). The proposed method was successfully used to separate and determine the six flavonoids in A. venetum leaf samples. Copyright © 2015 Elsevier B.V. All rights reserved.

[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 monosaccharides and sugar alcohols in tissues from diabetic rats by high-performance liquid chromatography with pulsed amperometric detection.

PubMed

Tomiya, N; Suzuki, T; Awaya, J; Mizuno, K; Matsubara, A; Nakano, K; Kurono, M

1992-10-01

A sensitive and simple high-performance liquid chromatographic method has been developed to determine the concentration of monosaccharides and sugar alcohols in animal tissues. Five neutral monosaccharides (D-glucose, D-galactose, D-mannose, D-fructose, and D-ribose) and three neutral sugar alcohols (myo-inositol, glycerol, and D-sorbitol) predominate in the renal cortices and sciatic nerves of rats. These monosaccharides and sugar alcohols were extracted with distilled water, purified by deproteinization with ethanol, a Sep-Pak C18 cartridge, and columns of Dowex 50W-X8 and Amberlite CG-400, then separated on Ca2+ and Pb2+ cation-exchange columns, eluted with deionized distilled water at 80 degrees C, and detected using integrated pulsed amperometry. About 10 pmol of each sugar was detectable with a signal-to-noise ratio of 10:1. D-Glucose, D-fructose, D-sorbitol, and D-mannose were higher in both the renal and sciatic tissues of diabetic rats than in those of normal animals. D-Ribose and glycerol were higher in the renal cortex of diabetic animals.

Determination of glutathione in human plasma using high-performance liquid chromatography with electrochemical detection with a carbon-epoxy resin composite electrode chemically modified with cobalt phthalocyanine.

PubMed

Wring, S A; Hart, J P; Birch, B J

1989-12-01

High-performance liquid chromatography with electrochemical detection (LCEC), incorporating a novel carbon-epoxy resin working electrode modified with cobalt phthalocyanine, has been employed for preliminary studies directed towards the determination of normal circulating levels of reduced glutathione (GSH) in human plasma. The mobile phase consisted of 0.05 M phosphate buffer (pH 3) containing 0.1% m/m ethylenediaminetetraacetic acid (EDTA); the calibration graph was linear in the range 0.24-30.7 ng of GSH injected. The mean recovery of GSH added to a control serum over the physiological concentration range (0.38-3.07 ng ml-1) was 99%; this was achieved following a simple sample pre-treatment method, prior to LCEC, involving chelation of divalent cations with EDTA and subsequent acidification with orthophosphoric acid. Using the LCEC method, the mean circulating level of GSH in plasma, found in three normal subjects, was 2.69 microM, GSH; this indicates that the method might be applicable to the determination of depressed circulating levels of GSH.

Determination of Flurbiprofen in Human Plasma by High-Performance Liquid Chromatography.

PubMed

Yilmaz, Bilal; Erdem, Ali Fuat

2015-10-01

A simple high-performance liquid chromatography method has been developed for determination of flurbiprofen in human plasma. The method was validated on an Ace C18 column using UV detection. The mobile phase was acetonitrile-0.05 M potassium dihydrogen phosphate solution (60:40, v/v) adjusted to pH 3.5 with phosphoric acid. The calibration curve was linear between the concentration range of 0.10-5.0 μg/mL. Intra- and inter-day precision values for flurbiprofen in plasma were <4.47, and accuracy (relative error) was better than 3.67%. The extraction recoveries of flurbiprofen from human plasma were between 93.0 and 98.9%. The limits of detection and quantification of flurbiprofen were 0.03 and 0.10 μg/mL, respectively. In addition, this assay was applied to determine the pharmacokinetic parameters of flurbiprofen in six healthy Turkish volunteers who had been given 100 mg flurbiprofen. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Metabolic profiling of nuciferine in rat urine, plasma, bile and feces after oral administration using ultra-high performance liquid chromatography-diode array detection-quadrupole time-of-flight mass spectrometry.

PubMed

Wu, Xiao-Lei; Wu, Ming-Jiang; Chen, Xin-Ze; Ma, Hao-Ling; Ding, Li-Qin; Qiu, Feng; Pan, Qin; Zhang, De-Qin

2017-06-05

Nuciferine, a major alkaloid found in Nelumbinis Folium, exhibits a broad spectrum of bioactivities, such as antiobesity, anti-diabetes and anti-inflammatory. However, many research regarding nuciferine focused on the extraction, isolation and biological activity, the metabolism is not comprehensively explained in vivo. Thence, the present of this paper is to establish a simple method for speculating metabolites of nuciferine. A total of 15 metabolites were detected and tentatively identified through ultra high performance liquid chromatography-diode array detection-quadrupole time-of-flight mass spectrometry (UHPLC-DAD-QTOF-MS), including 7 new metabolites. Among them, we also discovered a previously unmentioned metabolically active site at the C 1 -OCH 3 position. These metabolites suggested that demethylation, oxidation, glucuronidation and sulfation were major metabolic pathways. This study provided significant experiment basis for its safety estimate and valuable information about the metabolism of nuciferine, which will be advantageous for new drug development. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of organic acids by high-performance liquid chromatography with electrochemical detection during wine brewing.

PubMed

Kotani, Akira; Miyaguchi, Yuji; Tomita, Eiji; Takamura, Kiyoko; Kusu, Fumiyo

2004-03-24

Voltammetric determination of acids by means of the electrochemical reduction of quinone was applied to high-performance liquid chromatography (HPLC) with electrochemical detection (ED) for determining organic acids in fruit wines. A two-channel HPLC-ED system was fabricated by use of an ion-exclusion column and an electrochemical detector with a glassy carbon working electrode. Aqueous solution of 0.1 mM HClO(4) and ethanol containing 2-methyl-1,4-naphthoquinone served as a mobile phase and reagent solution, respectively. Determination of acetic, citric, lactic, malic, succinic, and tartaric acids was made by measuring the peak areas of the flow signals due to the reduction current of quinone caused by the eluted acids. The peak area was found to be linearly related to the acid amount ranging from 0.1 to 40 nmol per 20 microL injection. The present method was characterized by reproducibility with the simple and rapid procedure without derivatization of analytes. The method was shown as an effective means for following acid contents in fruit juices during fermentation with wine yeast.

Graphene oxide-coated stir bar sorptive extraction of trace aflatoxins from soy milk followed by high performance liquid chromatography-laser-induced fluorescence detection.

PubMed

Ma, Haiyan; Ran, Congcong; Li, Mengjiao; Gao, Jinglin; Wang, Xinyu; Zhang, Lina; Bian, Jing; Li, Junmei; Jiang, Ye

2018-04-01

Mycotoxins are potential food pollutants produced by fungi. Among them, aflatoxins (AFs) are the most toxic. Therefore, AFs were selected as models, and a sensitive, simple and green graphene oxide (GO)-based stir bar sorptive extraction (SBSE) method was developed for extraction and determination of AFs with high performance liquid chromatography-laser-induced fluorescence detector (HPLC-LIF). This method improved the sensitivity of AFs detection and solved the deposition difficulty of the direct use of GO as adsorbent. Several parameters including a spiked amount of NaCl, stirring rate, extraction time and desorption time were investigated. Under optimal conditions, the quantitative method had low limits of detection of 2.4-8.0 pg/mL, which were better than some reported AFs analytical methods. The developed method has been applied to soy milk samples with good recoveries ranging from 80.5 to 102.3%. The prepared GO-based SBSE can be used as a sensitive screening technique for detecting AFs in soy milk.

Probing Hydrogen Diffusion under High Pressure

NASA Astrophysics Data System (ADS)

Bove, L. E.; Klotz, S.; Strassle, T.; Saitta, M.

2012-12-01

The study of the microscopic mechanism governing hydrogen and hydrogen-based liquids (as water, ammonia and methane) diffusion is crucial for a variety of scientific issues spanning most of natural sciences. As an example, characterizing hydrogen diffusion in a confined medium, like in porous systems or zeolites, is fundamental in problems relating to environment, hydrogen storage and industrial applications [1]. The presence of water diffusion in the minerals of the Earth's mantle have strong incidence on the processes governing volcanic eruptions and intermediate-depth seismicity. As last example, knowing in details the microscopic dynamics of hydrogen-based simple liquids under extreme conditions is essential in order to interpret observations and develop models of planet interiors [2]. On the other hand, water and other simple hydrogen-based liquids have always been key systems in the development of modern condensed-matter physics, because of their simple electronic structure and the peculiar properties deriving from the hydrogen-bond network. Their high compressibility and chemical reactivity have made these systems very challenging to study experimentally under static high P-T conditions. In the last few years, a large effort has been undertaken by several groups around the world [2] to extend the static and dynamic techniques to high temperatures and pressures, a program in which our group has been actively involved [3-6]. However, while the structure of water and other hydrogenated liquids of geological interest, is now known up to almost 20 GPa, the study of their transport properties greatly lags behind. We have recently developed a new large-volume gasket-anvil ensemble for the Paris-Edinburgh press based on a novel toroidal design [7], which allows to perform quasi elastic neutron scattering measurements on hydrogen based liquids up to one order of magnitude higher pressures (5 GPa) respect to what was achievable with standard methods [8]. The large volume HP press can be now warmed up to 600K and the peculiar geometry of the gasket assure an excellent signal to background ratio. This new device has been recently settled up on neutron scattering facilities (PSI, ILL), successfully showing that very high quality data can be obtained on liquid water, and more generally on hydrogenated liquids dynamics under high pressure. Some new exciting results on the diffusion mechanism in hot dense water will be presented [9]. Possible future implementation of the device to reach the 20GPa and 1000K conditions will be also discussed. References [1] C. Cavazzoni et al., Science 283, 44 (1999) ; T. Guillot, Science 286 (1999), 72 . 77. [2] Some of the most active groups in this field are the Geophysical Laboratory (USA), Lawrence Livermore National Laboratory (USA), CEA/DAM (France) and the Bayerisches Geoinstitut (Allemagne). [3] Klotz S et al, Phys. Rev. Lett. 96 149602, 2006. [4] Nelmes R J Nature Phys. 2 414, 2006. [5] S. Klotz, L. Bove et al., Nature Mat. 8, 405 (2009). [6] L.E. Bove et al., Phys. Rev. Lett., 106 (2011) . [7] L. E. Bove et al., Phys. Appl. Lett., in preparation (2012). [8] A. Cunsolo et al., Journal of Chem. Phys. 124, 084503 (2006). [9] L.E. Bove et al., Phys. Rev. Lett., submitted (2012) .

MAGNETIC LIQUID DEFORMABLE MIRRORS FOR ASTRONOMICAL APPLICATIONS: ACTIVE CORRECTION OF OPTICAL ABERRATIONS FROM LOWER-GRADE OPTICS AND SUPPORT SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borra, E. F., E-mail: borra@phy.ulaval.ca

2012-08-01

Deformable mirrors are increasingly used in astronomy. However, they still are limited in stroke for active correction of high-amplitude optical aberrations. Magnetic liquid deformable mirrors (MLDMs) are a new technology that has the advantages of high-amplitude deformations and low costs. In this paper, we demonstrate extremely high strokes and interactuator strokes achievable by MLDMs which can be used in astronomical instrumentation. In particular, we consider the use of such a mirror to suggest an interesting application for the next generation of large telescopes. We present a prototype 91 actuator deformable mirror made of a magnetic liquid (ferrofluid). This mirror usesmore » a technique that linearizes the response of such mirrors by superimposing a large and uniform magnetic field on the magnetic field produced by an array of small coils. We discuss experimental results that illustrate the performance of MLDMs. A most interesting application of MLDMs comes from the fact they could be used to correct the aberrations of large and lower optical quality primary mirrors held by simple support systems. We estimate basic parameters of the needed MLDMs, obtaining reasonable values.« less

Concurrent determination of olanzapine, risperidone and 9-hydroxyrisperidone in human plasma by ultra performance liquid chromatography with diode array detection method: application to pharmacokinetic study.

PubMed

Siva Selva Kumar, M; Ramanathan, M

2016-02-01

A simple and sensitive ultra-performance liquid chromatography (UPLC) method has been developed and validated for simultaneous estimation of olanzapine (OLZ), risperidone (RIS) and 9-hydroxyrisperidone (9-OHRIS) in human plasma in vitro. The sample preparation was performed by simple liquid-liquid extraction technique. The analytes were chromatographed on a Waters Acquity H class UPLC system using isocratic mobile phase conditions at a flow rate of 0.3 mL/min and Acquity UPLC BEH shield RP18 column maintained at 40°C. Quantification was performed on a photodiode array detector set at 277 nm and clozapine was used as internal standard (IS). OLZ, RIS, 9-OHRIS and IS retention times were found to be 0.9, 1.4, .1.8 and 3.1 min, respectively, and the total run time was 4 min. The method was validated for selectivity, specificity, recovery, linearity, accuracy, precision and sample stability. The calibration curve was linear over the concentration range 1-100 ng/mL for OLZ, RIS and 9-OHRIS. Intra- and inter-day precisions for OLZ, RIS and 9-OHRIS were found to be good with the coefficient of variation <6.96%, and the accuracy ranging from 97.55 to 105.41%, in human plasma. The validated UPLC method was successfully applied to the pharmacokinetic study of RIS and 9-OHRIS in human plasma. Copyright © 2015 John Wiley & Sons, Ltd.

Fast and parallel determination of PCB 77 and PCB 180 in plasma using ultra performance liquid chromatography with diode array detection: A pharmacokinetic study in Swiss albino mouse.

PubMed

Ramanujam, N; Sivaselvakumar, M; Ramalingam, S

2017-11-01

A simple, sensitive and reproducible ultra-performance liquid chromatography (UPLC) method has been developed and validated for simultaneous estimation of polychlorinated biphenyl (PCB) 77 and PCB 180 in mouse plasma. The sample preparation was performed by simple liquid-liquid extraction technique. The analytes were chromatographed on a Waters Acquity H class UPLC system using isocratic mobile phase conditions at a flow rate of 0.3 mL/min and Acquity UPLC BEH shield RP 18 column maintained at 35°C. Quantification was performed on a photodiode array detector set at 215 nm and PCB 101 was used as internal standard (IS). PCB 77, PCB 180, and IS retention times were 2.6, 4.7 and 2.8 min, respectively, and the total run time was 6 min. The method was validated for specificity, selectivity, recovery, linearity, accuracy, precision and sample stability. The calibration curve was linear over the concentration range 10-3000 ng/mL for PCB 77 and PCB 180. Intra- and inter-day precisions for PCBs 77 and 180 were found to be good with CV <4.64%, and the accuracy ranged from 98.90 to 102.33% in mouse plasma. The validated UPLC method was successfully applied to the pharmacokinetic study of PCBs 77 and 180 in mouse plasma. Copyright © 2017 John Wiley & Sons, Ltd.

[Analysis of microalbuminuria with immunonephelometry and high performance liquid chromatography. Evaluation of new criteria].

PubMed

Markó, Lajos; Molnár, Gergo Attila; Wagner, Zoltán; Koszegi, Tamás; Matus, Zoltán; Mohás, Márton; Kuzma, Mónika; Szijártó, István András; Wittmann, István

2008-01-13

Hypertension as well as type 2 diabetes mellitus is a major factor in population mortality. Both diseases damage the endothelium, the early sign of which is microalbuminuria, which can be screened by dipstick and can be diagnosed by using immuno-based and high performance liquid chromatography methods. Using high performance liquid chromatography, the non-immunoreactive albumin can be detected as well. The authors aimed at the examination of albuminuria in the case of immunonephelometrically negative patients with high performance liquid chromatography, in diabetic and hypertensive and non-diabetic hypertensive populations. The authors also wanted to compare the present (albumin-creatinine ratio: male: > or =2.5 mg/mmol, female: > or =3.5 mg/mmol) and a new criteria of the Heart Outcomes Prevention Evaluation study (patients without diabetes: immunological method, > or =0.7 mg/mmol; high performance liquid chromatography, > or =3.1 mg/mmol; individuals with diabetes: immunological method, > or =1.4 mg/mmol; high performance liquid chromatography, > or =5.2 mg/mmol) of microalbuminuria. Examination of fresh urines of 469 microalbuminuria negative patients by dipstick were performed by immunonephelometry. Patients, who were microalbuminuria negative by immunonephelometry as well, were further analyzed by high performance liquid chromatography using the Accumintrade mark Kit, based on size-exclusion chromatography. Three times higher albuminuria were found with high performance liquid chromatography than with immunonephelometry. The intraindividual coefficient of variation did not differ in the two methods (37 +/- 31% vs. 40 +/- 31%, p = 0.869; immunonephelometry vs. high performance liquid chromatography; mean +/- standard deviation). Using the present criteria for microalbuminuria, 43% of immunonephelometrically negative patients proved to be microalbuminuric by high performance liquid chromatography. Using the new criteria of the Heart Outcomes Prevention Evaluation study, the rate of microalbuminuria positivity among the immunonephelometrically negative patients decreased to 14.5% by high performance liquid chromatography and the decrease in the number of microalbuminuria positive cases by high performance liquid chromatography could be observed mainly in the diabetic and hypertensive group (49% vs. 7.5%), while slighter decrease could be observed in the non-diabetic hypertensive group (37% vs. 26.5%). Applying the traditional criteria, the strongest predictor was the male gender by the logistic regression analysis. In 28% of microalbuminuria negative patients by immunonephelometry the diagnosis of microalbuminuria can be established using high performance liquid chromatography. Almost in one-third of microalbuminuria negative patients by immunonephelometry the diagnosis of microalbuminuria can be established by high performance liquid chromatography for which diagnosis three constitutive urine examinations are still needed. New criteria determined by the Heart Outcomes Prevention Evaluation study can be used neither in case of diabetic and hypertensive patients, nor in the case of non-diabetic hypertensive patients. The gender as the most important predictor of microalbuminuria cannot be ignored.

Chocolate--A Sweet Conundrum.

ERIC Educational Resources Information Center

Beckett, Stephen

1988-01-01

Presented is a brief history of manufacturing chocolate and an outline of production methods. Describes laboratory techniques used to monitor liquid chocolate viscosity. Discusses a simple experiment which can be performed in the classroom. (Author/CW)

Remote sensing of liquid level measurement using Fiber Bragg grating sensor

NASA Astrophysics Data System (ADS)

Sengupta, Dipankar; Shankar, M. Sai; Srimannarayana, K.; Vengal Rao, P.

2013-09-01

The present work proposes a simple low cost sensor head design making use of FBG sensor, for the measurement of liquid level. The sensor head consists of a lever, a buoyancy tube and an FBG. The lever is used to transfer the buoyancy force due to change in liquid level to the FBG resulting in shift in Bragg wavelength. The Flexibility of this design enables to measure the liquid level in an open or closed tank. The arrangement shows that liquid level sensitivity is high and is 10.7pm/mm.

A continuous stream flash evaporator for the calibration of an IR cavity ring-down spectrometer for the isotopic analysis of water.

PubMed

Gkinis, Vasileios; Popp, Trevor J; Johnsen, Sigfus J; Blunier, Thomas

2010-12-01

A new technique for high-resolution simultaneous isotopic analysis of δ¹⁸O and δD in liquid water is presented. A continuous stream flash evaporator has been designed that is able to vapourise a stream of liquid water in a continuous mode and deliver a stable and finely controlled water vapour sample to a commercially available infrared cavity ring-down spectrometer. Injection of sub-microlitre amounts of the liquid water is achieved by pumping liquid water sample through a fused silica capillary and instantaneously vapourising it with 100% efficiency in a home-made oven at a temperature of 170 °C. The system's simplicity, low power consumption and low dead volume together with the possibility for automated unattended operation provides a solution for the calibration of laser instruments performing isotopic analysis of water vapour. Our work is mainly driven by the possibility to perform high-resolution online water isotopic analysis on continuous-flow analysis (CFA) systems typically used to analyse the chemical composition of ice cores drilled in polar regions. In the following, we describe the system's precision and stability and sensitivity to varying levels of sample size and we assess the observed memory effects. A test run with standard waters of different isotopic compositions is presented, demonstrating the ability to calibrate the spectrometer's measurements on a VSMOW scale with a relatively simple and fast procedure.

Pressure ratio effects on self-similar scalar mixing of high-pressure turbulent jets in a pressurized volume

NASA Astrophysics Data System (ADS)

Ruggles, Adam; Pickett, Lyle; Frank, Jonathan

2014-11-01

Many real world combustion devices model fuel scalar mixing by assuming the self-similar argument established in atmospheric free jets. This allows simple prediction of the mean and rms fuel scalar fields to describe the mixing. This approach has been adopted in super critical liquid injections found in diesel engines where the liquid behaves as a dense fluid. The effect of pressure ratio (injection to ambient) when the ambient is greater than atmospheric pressure, upon the self-similar collapse has not been well characterized, particularly the effect upon mixing constants, jet spreading rates, and virtual origins. Changes in these self-similar parameters control the reproduction of the scalar mixing statistics. This experiment investigates the steady state mixing of high pressure ethylene jets in a pressurized pure nitrogen environment for various pressure ratios and jet orifice diameters. Quantitative laser Rayleigh scattering imaging was performed utilizing a calibration procedure to account for the pressure effects upon scattering interference within the high-pressure vessel.

UHPLC-UV method for the determination of flavonoids in dietary supplements and for evaluation of their antioxidant activities.

PubMed

Magiera, Sylwia; Baranowska, Irena; Lautenszleger, Anna

2015-01-01

A simple and rapid ultra-high performance liquid chromatographic (UHPLC) method coupled with an ultraviolet detector (UV) has been developed and validated for the separation and determination of 14 major flavonoids ((±)-catechin, (-)-epicatechin, glycitin, (-)-epicatechin gallate, rutin, quercitrin, hesperidine, neohesperidine, daidzein, glycitein, quercetin, genistein, hesperetin, and biochanin A) in herbal dietary supplements. The flavonoids have been separated on a Chromolith Fast Gradient Monolithic RP-18e column utilizing a mobile phase composed of 0.05% trifluoroacetic acid in water and acetonitrile in gradient elution mode. Under these conditions, flavonoids were separated in a 5 min run. The selectivity of the developed UHPLC-UV method was confirmed by comparison with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis. The validation parameters such as linearity, sensitivity, precision, and accuracy were found to be highly satisfactory. The optimized method was applied to determination of flavonoids in different dietary supplements. Additionally, the developed HPLC-UV method combined with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay was used in the evaluation of antioxidant activity of the selected flavonoids. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of rivaroxaban in patient's plasma samples by anti-Xa chromogenic test associated to High Performance Liquid Chromatography tandem Mass Spectrometry (HPLC-MS/MS).

PubMed

Derogis, Priscilla Bento Matos; Sanches, Livia Rentas; de Aranda, Valdir Fernandes; Colombini, Marjorie Paris; Mangueira, Cristóvão Luis Pitangueira; Katz, Marcelo; Faulhaber, Adriana Caschera Leme; Mendes, Claudio Ernesto Albers; Ferreira, Carlos Eduardo Dos Santos; França, Carolina Nunes; Guerra, João Carlos de Campos

2017-01-01

Rivaroxaban is an oral direct factor Xa inhibitor, therapeutically indicated in the treatment of thromboembolic diseases. As other new oral anticoagulants, routine monitoring of rivaroxaban is not necessary, but important in some clinical circumstances. In our study a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was validated to measure rivaroxaban plasmatic concentration. Our method used a simple sample preparation, protein precipitation, and a fast chromatographic run. It was developed a precise and accurate method, with a linear range from 2 to 500 ng/mL, and a lower limit of quantification of 4 pg on column. The new method was compared to a reference method (anti-factor Xa activity) and both presented a good correlation (r = 0.98, p < 0.001). In addition, we validated hemolytic, icteric or lipemic plasma samples for rivaroxaban measurement by HPLC-MS/MS without interferences. The chromogenic and HPLC-MS/MS methods were highly correlated and should be used as clinical tools for drug monitoring. The method was applied successfully in a group of 49 real-life patients, which allowed an accurate determination of rivaroxaban in peak and trough levels.

Bifocal computational near eye light field displays and Structure parameters determination scheme for bifocal computational display.

PubMed

Liu, Mali; Lu, Chihao; Li, Haifeng; Liu, Xu

2018-02-19

We propose a bifocal computational near eye light field display (bifocal computational display) and structure parameters determination scheme (SPDS) for bifocal computational display that achieves greater depth of field (DOF), high resolution, accommodation and compact form factor. Using a liquid varifocal lens, two single-focal computational light fields are superimposed to reconstruct a virtual object's light field by time multiplex and avoid the limitation on high refresh rate. By minimizing the deviation between reconstructed light field and original light field, we propose a determination framework to determine the structure parameters of bifocal computational light field display. When applied to different objective to SPDS, it can achieve high average resolution or uniform resolution display over scene depth range. To analyze the advantages and limitation of our proposed method, we have conducted simulations and constructed a simple prototype which comprises a liquid varifocal lens, dual-layer LCDs and a uniform backlight. The results of simulation and experiments with our method show that the proposed system can achieve expected performance well. Owing to the excellent performance of our system, we motivate bifocal computational display and SPDS to contribute to a daily-use and commercial virtual reality display.

A comparative study of first-derivative spectrophotometry and column high-performance liquid chromatography applied to the determination of repaglinide in tablets and for dissolution testing.

PubMed

AlKhalidi, Bashar A; Shtaiwi, Majed; AlKhatib, Hatim S; Mohammad, Mohammad; Bustanji, Yasser

2008-01-01

A fast and reliable method for the determination of repaglinide is highly desirable to support formulation screening and quality control. A first-derivative UV spectroscopic method was developed for the determination of repaglinide in tablet dosage form and for dissolution testing. First-derivative UV absorbance was measured at 253 nm. The developed method was validated for linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ) in comparison to the U.S. Pharmacopeia (USP) column high-performance liquid chromatographic (HPLC) method. The first-derivative UV spectrophotometric method showed excellent linearity [correlation coefficient (r) = 0.9999] in the concentration range of 1-35 microg/mL and precision (relative standard deviation < 1.5%). The LOD and LOQ were 0.23 and 0.72 microg/mL, respectively, and good recoveries were achieved (98-101.8%). Statistical comparison of results of the first-derivative UV spectrophotometric and the USP HPLC methods using the t-test showed that there was no significant difference between the 2 methods. Additionally, the method was successfully used for the dissolution test of repaglinide and was found to be reliable, simple, fast, and inexpensive.

In-syringe demulsified dispersive liquid-liquid microextraction and high performance liquid chromatography-mass spectrometry for the determination of trace fungicides in environmental water samples.

PubMed

Xia, Yating; Cheng, Min; Guo, Feng; Wang, Xiangfang; Cheng, Jing

2012-04-29

An in-syringe demulsified dispersive liquid-liquid microextraction (ISD-DLLME) technique was developed using low-density extraction solvents for the highly sensitive determination of the three trace fungicides (azoxystrobin, diethofencarb and pyrimethanil) in water samples by high performance liquid chromatography-mass spectrometry chromatography-diode array detector/electrospray ionisation mass spectrometry. In the proposed technique, a 5-mL syringe was used as an extraction, separation and preconcentration container. The emulsion was obtained after the mixture of toluene (extraction solvent) and methanol (dispersive solvent) was injected into the aqueous bulk of the syringe. The obtained emulsion cleared into two phases without centrifugation, when an aliquot of methanol was introduced as a demulsifier. The separated floating organic extraction solvent was impelled and collected into a pipette tip fitted to the tip of the syringe. Under the optimal conditions, the enrichment factors for azoxystrobin, diethofencarb and pyrimethanil were 239, 200, 195, respectively. The limits of detection, calculated as three times the signal-to-noise ratio (SN(-1)), were 0.026 μg L(-1) for azoxystrobin, 0.071 μg L(-1) for diethofencarb and 0.040 μg L(-1) for pyrimethanil. The repeatability study was carried out by extracting the spiked water samples at concentration levels of 0.02 μg mL(-1) for all the three fungicides. The relative standard deviations varied between 4.9 and 8.2% (n=5). The recoveries of all the three fungicides from tap, lake and rain water samples at spiking levels of 0.2, 1, 5 μg L(-1) were in the range of 90.0-105.0%, 86.0-114.0% and 88.6-110.0%, respectively. The proposed ISD-DLLME technique was demonstrated to be simple, practical and efficient for the determination of different kinds of fungicide residues in real water samples. Copyright © 2012. Published by Elsevier B.V.

Improvement in device performance from a mixture of a liquid crystal and photosensitive acrylic prepolymer with the photoinduced vertical alignment method

PubMed Central

Ho, Czung-Yu; Lin, Fa-Hsin; Tao, Yu-Tai; Lee, Jiunn-Yih

2011-01-01

In a multicomponent nematic liquid crystal (NLC) mixture of a liquid crystal (negative-type NLC) and a photosensitive acrylic prepolymer, photopolymerization upon UV irradiation induces the separation of the LC and photosensitive acrylic prepolymer layers, thereby leading to a vertical arrangement of LC molecules. In this study, we propose a simple vertical alignment method for LC molecules, by adding a chiral smectic A (SmA∗) liquid crystal having homeotropic texture characteristics to an NLC mixture solution. Measurements of electro-optical properties revealed that the addition of the SmA∗ LC not only strengthened the anchoring force of the copolymer alignment film surface, but also significantly enhanced the contrast ratio (∼73%), response time and grayscale switching performance of the device. PMID:27877462

A physical retrieval of cloud liquid water over the global oceans using special sensor microwave/imager (SSM/I) observations

NASA Astrophysics Data System (ADS)

Greenwald, Thomas J.; Stephens, Graeme L.; Vonder Haar, Thomas H.; Jackson, Darren L.

1993-10-01

A method of remotely sensing integrated cloud liquid water over the oceans using spaceborne passive measurements from the special sensor microwave/imager (SSM/I) is described. The technique is comprised of a simple physical model that uses the 19.35- and 37-GHz channels of the SSM/I. The most comprehensive validation to date of cloud liquid water estimated from satellites is presented. This is accomplished through a comparison to independent ground-based microwave radiometer measurements of liquid water on San Nicolas Island, over the North Sea, and on Kwajalein and Saipan Islands in the western Pacific. In areas of marine stratocumulus clouds off the coast of California a further comparison is made to liquid water inferred from advanced very high resolution radiometer (AVHRR) visible reflectance measurements. The results are also compared qualitatively with near-coincident satellite imagery and with other existing microwave methods in selected regions. These comparisons indicate that the liquid water amounts derived from the simple scheme are consistent with the ground-based measurements for nonprecipitating cloud systems in the subtropics and middle to high latitudes. The comparison in the tropics, however, was less conclusive. Nevertheless, the retrieval method appears to have general applicability over most areas of the global oceans. An observational measure of the minimum uncertainty in the retrievals is determined in a limited number of known cloud-free areas, where the liquid water amounts are found to have a low variability of 0.016 kg m-2. A simple sensitivity and error analysis suggests that the liquid water estimates have a theoretical relative error typically ranging from about 25% to near 40% depending on the atmospheric/surface conditions and on the amount of liquid water present in the cloud. For the global oceans as a whole the average cloud liquid water is determined to be about 0.08 kg m-2. The major conclusion of this paper is that reasonably accurate amounts of cloud liquid water can be retrieved from SSM/I observations for nonprecipitating cloud systems, particularly in areas of persistent stratocumulus clouds, with less accurate retrievals in tropical regions.

Rapid determination of the various native forms of vitamin B6 and B2 in cow's milk using ultra-high performance liquid chromatography.

PubMed

Schmidt, A; Schreiner, M G; Mayer, H K

2017-06-02

As the formation of pyridoxal phosphate, the active cofactor of vitamin B 6 , is dependent on riboflavin 5-phosphate, we propose a fast and simple ultra-high performance liquid chromatography method for the simultaneous determination of the native B 6 vitamers pyridoxal, pyridoxine, pyridoxamine, their mono phosphorus esters and 4-pyridoxic acid as well as vitamin B 2 as riboflavin and its phosphorus ester riboflavin 5-phosphate in milk. Separation was achieved under 6.0min by reversed-phase and pH gradient elution. Sample preparation was optimized regarding various acids and pH levels. Changes in those parameters led to significant deviations of sample matrix breakdown efficiency. The optimized method was then validated regarding specificity, accuracy, precision, linearity, range, detection and quantification limits. As the method performed satisfactory, is was used to study commercial liquid cow's milk (n=31), regarding effects of the employed preservation technique (pasteurization, extended shelf-life, ultra-high temperature) on the composition and content of B 6 and B 2 vitamers. In cow's milk, vitamin B 6 mostly consists of pyridoxal and its phosphate ester, with pyridoxal phosphate being the bulk component. The catabolite of the vitamin B 6 metabolism, 4-pyridoxic acid was present in significant amounts in all studied samples, with up to 2.69μmolL -1 . Vitamin B 2 was present as riboflavin and its phosphate ester up to 12.86μmolL -1 . Copyright © 2017 Elsevier B.V. All rights reserved.

Accelerated gas-liquid visible light photoredox catalysis with continuous-flow photochemical microreactors.

PubMed

Straathof, Natan J W; Su, Yuanhai; Hessel, Volker; Noël, Timothy

2016-01-01

In this protocol, we describe the construction and use of an operationally simple photochemical microreactor for gas-liquid photoredox catalysis using visible light. The general procedure includes details on how to set up the microreactor appropriately with inlets for gaseous reagents and organic starting materials, and it includes examples of how to use it to achieve continuous-flow preparation of disulfides or trifluoromethylated heterocycles and thiols. The reported photomicroreactors are modular, inexpensive and can be prepared rapidly from commercially available parts within 1 h even by nonspecialists. Interestingly, typical reaction times of gas-liquid visible light photocatalytic reactions performed in microflow are lower (in the minute range) than comparable reactions performed as a batch process (in the hour range). This can be attributed to the improved irradiation efficiency of the reaction mixture and the enhanced gas-liquid mass transfer in the segmented gas-liquid flow regime.

Sample preparation combined with electroanalysis to improve simultaneous determination of antibiotics in animal derived food samples.

PubMed

da Silva, Wesley Pereira; de Oliveira, Luiz Henrique; Santos, André Luiz Dos; Ferreira, Valdir Souza; Trindade, Magno Aparecido Gonçalves

2018-06-01

A procedure based on liquid-liquid extraction (LLE) and phase separation using magnetically stirred salt-induced high-temperature liquid-liquid extraction (PS-MSSI-HT-LLE) was developed to extract and pre-concentrate ciprofloxacin (CIPRO) and enrofloxacin (ENRO) from animal food samples before electroanalysis. Firstly, simple LLE was used to extract the fluoroquinolones (FQs) from animal food samples, in which dilution was performed to reduce interference effects to below a tolerable threshold. Then, adapted PS-MSSI-HT-LLE protocols allowed re-extraction and further pre-concentration of target analytes in the diluted acid samples for simultaneous electrochemical quantification at low concentration levels. To improve the peak separation, in simultaneous detection, a baseline-corrected second-order derivative approach was processed. These approaches allowed quantification of target FQs from animal food samples spiked at levels of 0.80 to 2.00 µmol L -1 in chicken meat, with recovery values always higher than 80.5%, as well as in milk samples spiked at 4.00 µmol L -1 , with recovery values close to 70.0%. Copyright © 2018 Elsevier Ltd. All rights reserved.

An improved ionic liquid-based headspace single-drop microextraction-liquid chromatography method for the analysis of camphor and trans-anethole in compound liquorice tablets.

PubMed

He, Xiaowen; Zhang, Fucheng; Jiang, Ye

2012-07-01

A simple, accurate and sensitive ionic liquid-based headspace single-drop microextraction procedure followed by high-performance liquid chromatography was developed and validated for the determination of camphor and trans-anethole in compound liquorice tablets. The volume of the ionic liquid microdrop was increased to 12 µL by modifying the device of the suspended drop. The stability of the microdrop and the sensitivity of the method were improved. Under the optimum experimental conditions, the calculated calibration curves gave acceptable linearity for camphor and trans-anethole with correlation coefficients of 0.9990 and 0.9998, respectively. The repeatability of the proposed method, expressed as relative standard deviation, was below 4.5% (n = 5). The limits of detection for the two target analytes were found to be 9.77 and 1.95 × 10(-2) μg/mL, respectively. In this study, the separation, purification and enrichment were achieved in one step in an airtight system, which reduced the interferences caused by other complicated constituents, increased the signal-to-noise of the method and ensured the accuracy of the results because there was no loss of volatile components. It is expected to be widely applied for sample pretreatment of volatile components with high boiling points in samples with complicated matrices such as the extractions of plants or Chinese traditional drugs.

Determination of tylosin residues in different animal tissues by high performance liquid chromatography.

PubMed

Prats, C; Francesch, R; Arboix, M; Pérez, B

2002-01-05

A HPLC method to determine and quantify tylosin residues from calves, pigs and poultry is reported. This procedure permitted tylosin to be separated from muscle, liver, kidney and fat after a simple extraction with chloroform or ethyl acetate under basic conditions. The analytical methodology showed a high specificity and sensitivity and an adequate precision and accuracy with a limit of quantification of 50 microg/kg. Eight calves were administered 20 mg/kg/day of tylosin for 5 days and slaughtered at 7 and 14 days post-administration. Results showed that at the 14th day tylosin levels were lower than the MRL in all target tissues.

Physics on Tap

ERIC Educational Resources Information Center

Wheeler, Andrew P. S.

2012-01-01

This article aims to describe how to visualize surface tension effects in liquid jets. A simple experiment is proposed using the liquid jet flow from a mains water tap/faucet. Using a modern digital camera with a high shutter speed, it is possible to visualize the instabilities (capillary waves) that form within the jet due to the action of…

Rapid Screening and Characterization of Acetylcholinesterase Inhibitors from Yinhuang Oral Liquid Using Ultrafiltration-liquid Chromatography-electrospray Ionization Tandem Mass Spectrometry

PubMed Central

Zhang, Haomin; Guo, Yinan; Meng, Lingwen; Sun, Hui; Yang, Yinping; Gao, Ying; Sun, Jiaming

2018-01-01

Background: At present, approximately 17–25 million people in the world suffer from Alzheimer's disease (AD). The most efficacious and acceptable therapeutic drug clinically are the acetylcholinesterase inhibitors (AChEIs). Yinhuang oral liquid is a Chinese medicine preparation which contains AChEIs according to the literatures. However, no strategy has been presented for rapid screening and identification of AChEIs from Yinhuang oral liquid. Objective: To develop a method for rapid screening and identification of AChEIs from Yinhuang oral liquid using ultrafiltration–liquid chromatography–electrospray ionization tandem mass spectrometry (UF-LC-ESI-MS/MS). Materials and Methods: In this study, UF incubation conditions such as enzyme concentration, incubation time, and incubation temperature were optimized so as to get better screening results. The AChEIs from Yinhuang oral liquid were identified by high-performance liquid chromatography-ESI-MS and the improved Ellman method was used for the AChE inhibitory activity test in vitro. Results: The results showed that Yinhuang oral liquid can inhibit the activity of AChE. We screened and identified seven compounds with potential AChE inhibitory activity from Yinhuang oral liquid, which provided experimental basis for the treatment and prevention of AD. Conclusion: The current technique was used to directly screen the active ingredients with acetylcholinesterase inhibition from complex traditional Chinese medicine, which was simple, rapid, accurate, and suitable for high-throughput screening of AChEI from complex systems. SUMMARY A UF-LC-ESI-MS/MS method for rapid screening and identification of AChEIs from Yinhuang oral liquid was developedSeven compounds were screened and identified with potential AChE inhibitory activity from Yinhuang oral liquidIt provided experimental basis of Yinhuang oral liquid for the treating and preventing AD. Abbreviations used: (AD): Alzheimer's disease; (UF-LC-ESI-MS/MS): ultrafiltration–liquid chromatography–electrospray ionization tandem mass spectrometry; (AChEIs): acetylcholinesterase inhibitors. PMID:29720840

Offline solid-phase extraction for preconcentration of pharmaceuticals and personal care products in environmental water and their simultaneous determination using the reversed phase high-performance liquid chromatography method.

PubMed

G Archana; Dhodapkar, Rita; Kumar, Anupama

2016-09-01

The present study reports a precise and simple offline solid-phase extraction (SPE) coupled with reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination of five representative and commonly present pharmaceuticals and personal care products (PPCPs), a new class of emerging pollutants in the aquatic environment. The target list of analytes including ciprofloxacin, acetaminophen, caffeine benzophenone and irgasan were separated by a simple HPLC method. The column used was a reversed-phase C18 column, and the mobile phase was 1 % acetic acid and methanol (20:80 v/v) under isocratic conditions, at a flow rate of 1 mL min(-1). The analytes were separated and detected within 15 min using the photodiode array detector (PDA). The linearity of the calibration curves were obtained with correlation coefficients 0.98-0.99.The limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and ruggedness demonstrated the reproducibility, specificity and sensitivity of the developed method. Prior to the analysis, the SPE was performed using a C18 cartridge to preconcentrate the targeted analytes from the environmental water samples. The developed method was applied to evaluate and fingerprint PPCPs in sewage collected from a residential engineering college campus, polluted water bodies such as Nag river and Pili river and the influent and effluent samples from a sewage treatment plant (STP) situated at Nagpur city, in the peak summer season. This method is useful for estimation of pollutants present in microquantities in the surface water bodies and treated sewage as compared to nanolevel pollutants detected by mass spectrometry (MS) detectors.

Gas-exfoliated porous monolayer boron nitride for enhanced aerobic oxidative desulfurization performance.

PubMed

Wu, Yingcheng; Wu, Peiwen; Chao, Yanhong; He, Jing; Li, Hongping; Lu, Linjie; Jiang, Wei; Zhang, Beibei; Li, Huaming; Zhu, Wenshuai

2018-01-12

Hexagonal boron nitride has been regarded to be an efficient catalyst in aerobic oxidation fields, but limited by the less-exposed active sites. In this contribution, we proposed a simple green liquid nitrogen gas exfoliation strategy for preparation of porous monolayer nanosheets (BN-1). Owing to the reduced layer numbers, decreased lateral sizes and artificially-constructed pores, increased exposure of active sites was expected, further contributed to an enhanced aerobic oxidative desulfurization (ODS) performance up to ∼98% of sulfur removal, achieving ultra-deep desulfurization. This work not only introduced an excellent catalyst for aerobic ODS, but also provided a strategy for construction of some other highly-efficient monolayer two-dimensional materials for enhanced catalytic performance.

Gas-exfoliated porous monolayer boron nitride for enhanced aerobic oxidative desulfurization performance

NASA Astrophysics Data System (ADS)

Wu, Yingcheng; Wu, Peiwen; Chao, Yanhong; He, Jing; Li, Hongping; Lu, Linjie; Jiang, Wei; Zhang, Beibei; Li, Huaming; Zhu, Wenshuai

2018-01-01

Hexagonal boron nitride has been regarded to be an efficient catalyst in aerobic oxidation fields, but limited by the less-exposed active sites. In this contribution, we proposed a simple green liquid nitrogen gas exfoliation strategy for preparation of porous monolayer nanosheets (BN-1). Owing to the reduced layer numbers, decreased lateral sizes and artificially-constructed pores, increased exposure of active sites was expected, further contributed to an enhanced aerobic oxidative desulfurization (ODS) performance up to ˜98% of sulfur removal, achieving ultra-deep desulfurization. This work not only introduced an excellent catalyst for aerobic ODS, but also provided a strategy for construction of some other highly-efficient monolayer two-dimensional materials for enhanced catalytic performance.

Modified extraction procedure for gas-liquid chromatography applied to the identification of anaerobic bacteria.

PubMed Central

Thomann, W R; Hill, G B

1986-01-01

Chloroform and ether commonly are used as solvents to extract metabolic organic acids for analysis by gas-liquid chromatography in the identification of anaerobic bacteria. Because these solvents are potentially hazardous to personnel, modified extraction procedures involving the use of a safer solvent, methyl tert-butyl ether were developed which remained both simple to perform and effective for organism identification. PMID:3700623

History of Solid Rockets

NASA Technical Reports Server (NTRS)

Green, Becky; Hales, Christy

2017-01-01

Solid rockets were created by accident and their design and uses have evolved over time. Solid rockets are more simple and reliable than liquid rockets, but they have reduced performance capability. All solid rockets have a similar set of failure modes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carpita, N.C.

We have just completed the second year of a three-year project entitled Biosynthesis assembly of cell wall polysaccharides in cereal grasses.'' We made significant progress on two aspects of cell wall synthesis in grasses and greatly refined gas-liquid and high- performance liquid chromatographic techniques necessary to identify the products of synthesis in vitro and in vivo. First, Dr. David Gibeaut, a post-doctoral associate, devised a convenient procedure for the enrichment of Golgi membranes by flotation centrifugation following initial downward rate-zonal separation. Based on comparison of the IDPase marker enzyme, flotation centrifugation enriched the Golgi apparatus almost 7-fold after the initialmore » downward separation. This system is now used in our studies of the synthesis in vitro of the mixed-linkage {beta}-D-glucan. Second, Gibeaut and I have devised a simple technique to feed radioactive sugars into intact growing seedlings and follow incorporation of radioactivity into and turnover from specific cell wall polysaccharides. The project has also provided a few spin-off projects that have been productive as well. First, in collaboration with the group of Prof. Peter Kaufman, University of Michigan, we examined changes in cell wall structure concomitant with reaction to gravistimulation in the gravisensing oat pulvinus. Second, Dr. Gibeaut developed a simple clean-up procedure for partially methylated alditol derivatives to remove a large amount of undesirable interfering compounds that confound separation of the derivatives by gas-liquid chromatography. 5 refs.« less

Simple Cloud Chambers Using Gel Ice Packs

ERIC Educational Resources Information Center

Kamata, Masahiro; Kubota, Miki

2012-01-01

Although cloud chambers are highly regarded as teaching aids for radiation education, school teachers have difficulty in using cloud chambers because they have to prepare dry ice or liquid nitrogen before the experiment. We developed a very simple and inexpensive cloud chamber that uses the contents of gel ice packs which can substitute for dry…

Quantitation of 5-Methyltetrahydrofolate in Cerebrospinal Fluid Using Liquid Chromatography-Electrospray Tandem Mass Spectrometry.

PubMed

Arning, Erland; Bottiglieri, Teodoro

2016-01-01

We describe a simple stable isotope dilution method for accurate and precise measurement of cerebrospinal fluid (CSF) 5-methyltetrahydrofolate (5-MTHF) as a clinical diagnostic test. 5-MTHF is the main biologically active form of folic acid and is involved in regulation of homocysteine and DNA synthesis. Measurement of 5-MTHF in CSF provides diagnostic information regarding diseases affecting folate metabolism within the central nervous system, in particular inborn errors of folate metabolism. Determination of 5-MTHF in CSF (50 μL) was performed utilizing high performance liquid chromatography coupled with electrospray positive ionization tandem mass spectrometry (HPLC-ESI-MS/MS). 5-MTHF in CSF is determined by a 1:2 dilution with internal standard (5-MTHF-(13)C5) and injected directly onto the HPLC-ESI-MS/MS system. Each assay is quantified using a five-point standard curve (25-400 nM) and has an analytical measurement range of 3-1000 nM.

Hydrophilic Interaction Liquid Chromatography-Tandem Mass Spectrometry Analysis of Fosetyl-Aluminum in Airborne Particulate Matter

PubMed Central

Di Filippo, Patrizia; Riccardi, Carmela; Pomata, Donatella; Marsiglia, Riccardo; Console, Carla; Puri, Daniele

2018-01-01

Fosetyl-aluminum is a synthetic fungicide administered to plants especially to prevent diseases caused by the members of the Peronosporales and several Phytophthora species. Herein, we present a selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to analyze residues of fosetyl-A1 in air particulate matter. This study was performed in perspective of an exposure assessment of this substance of health concern in environments where high levels of fosetly-Al, relatively to airborne particulate matter, can be found after spraying it. The cleanup procedure of the analyte, from sampled filters of atmospheric particulate matter, was optimized using a Strata X solid-phase extraction cartridge, after accelerated extraction by using water. The chromatographic separation was achieved using a polymeric column based on hydrophilic interaction in step elution with water/acetonitrile, whereas the mass spectrometric detection was performed in negative electrospray ionization. The proposed method resulted to be a simple, fast, and suitable method for confirmation purposes. PMID:29686933

Photolithography-Based Patterning of Liquid Metal Interconnects for Monolithically Integrated Stretchable Circuits.

PubMed

Park, Chan Woo; Moon, Yu Gyeong; Seong, Hyejeong; Jung, Soon Won; Oh, Ji-Young; Na, Bock Soon; Park, Nae-Man; Lee, Sang Seok; Im, Sung Gap; Koo, Jae Bon

2016-06-22

We demonstrate a new patterning technique for gallium-based liquid metals on flat substrates, which can provide both high pattern resolution (∼20 μm) and alignment precision as required for highly integrated circuits. In a very similar manner as in the patterning of solid metal films by photolithography and lift-off processes, the liquid metal layer painted over the whole substrate area can be selectively removed by dissolving the underlying photoresist layer, leaving behind robust liquid patterns as defined by the photolithography. This quick and simple method makes it possible to integrate fine-scale interconnects with preformed devices precisely, which is indispensable for realizing monolithically integrated stretchable circuits. As a way for constructing stretchable integrated circuits, we propose a hybrid configuration composed of rigid device regions and liquid interconnects, which is constructed on a rigid substrate first but highly stretchable after being transferred onto an elastomeric substrate. This new method can be useful in various applications requiring both high-resolution and precisely aligned patterning of gallium-based liquid metals.

A simple validated multi-analyte method for detecting drugs in oral fluid by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

PubMed

Zheng, Yufang; Sparve, Erik; Bergström, Mats

2018-06-01

A UPLC-MS/MS method was developed to identify and quantitate 37 commonly abused drugs in oral fluid. Drugs of interest included amphetamines, benzodiazepines, cocaine, opiates, opioids, phencyclidine and tetrahydrocannabinol. Sample preparation and extraction are simple, and analysis times short. Validation showed satisfactory performance at relevant concentrations. The possibility of contaminated samples as well as the interpretation in relation to well-knows matrices, such as urine, will demand further study. Copyright © 2017 John Wiley & Sons, Ltd.

A simple method for the determination of glyphosate and aminomethylphosphonic acid in seawater matrix with high performance liquid chromatography and fluorescence detection.

PubMed

Wang, Shu; Liu, Baomin; Yuan, Dongxing; Ma, Jian

2016-12-01

Glyphosate (GLYP) is an important herbicide which is also used as the phosphorus source for marine organisms. The wide applications of GLYP can lead to its accumulation in oceans and coastal waters, thus creating environmental issues. However, there is limited methods for detection of GLYP and its degradation product, aminomethylphosphonic acid (AMPA) in saline samples. Therefore, a simple and fast method for the quantification of GLYP and AMPA in seawater matrix has been developed based on the derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl), separation with high performance liquid chromatography (HPLC) and detection with fluorescence detector (FLD). In order to maximize sensitivity, the derivatization procedure was carefully optimized regarding concentration of FMOC-Cl, volume of borate buffer, pH of borate buffer, mixing and derivatization time. The derivatization reaction could be completed within 30min in seawater samples without any additional clean-up or desalting steps. Under the optimized conditions, the developed HPLC method showed a wide linear response (up to several mg/L, R 2 >0.99). The limits of detection were 0.60μg/L and 0.30μg/L for GLYP and AMPA in seawater matrix, respectively. The relative standard deviation was 14.0% for GLYP (1.00mg/L) and 3.1% for AMPA (100μg/L) in saline samples with three different operators (n=24). This method was applied to determine the concentration of GLYP and AMPA in seawater culture media and the recovery data indicated minimal matrix interference. Due to its simplicity, high reproducibility and successful application in seawater culture media analysis, this method is a potentially useful analytical technique for both marine research and environmental science. Copyright © 2016 Elsevier B.V. All rights reserved.

A simple and precise method to detect sterol esterification activity of lecithin/cholesterol acyltransferase by high-performance liquid chromatography.

PubMed

Wang, Yu; Wang, Siming; Zhang, Lijiao; Zeng, Jie; Yang, Ruiyue; Li, Hongxia; Tang, Yueming; Chen, Wenxiang; Dong, Jun

2018-02-01

The measurement of lecithin: cholesterol acyltransferase (LCAT, EC 2.3.1.43) activity is important in high-density lipoprotein (HDL) metabolism study and cardiovascular disease (CVD) risk assessment. However, current methods suffer from complex design and preparation of exogenous substrate, low reproducibility, and interference of cofactors. In this study, we developed a simple and precise high performance liquid chromatography (HPLC) method for the measurement of LCAT activity. By using 7-dehydrocholesterol (7-DHC) and 1,2-didecanoyl-sn-glycero-3-phosphocholine(10:0PC) as substrates, and an LCAT activating peptide (P642) as activator and emulsifier, the substrate reagent was easily made by vortex. The substrate reagent was mixed with serum samples (50:1, v/v) and incubated at 37 °C for 1 h. After incubation, the lipid was extracted with hexane and ethanol. With a conjugated double bond and ultraviolet absorption, 7-DHC and its esterification product could be separated and analyzed by a single HPLC run without calibration. LCAT activity was a linear function of the serum sample volume and the intra- and total assay coefficients of variation (CV) less than 2.5% were obtained under the standardized conditions. The substrate reagent was stable, and assay result accurately reflected LCAT activity. LCAT activities in 120 healthy subjects were positively correlated with triglyceride (P < 0.05), fractional esterification rate of HDL cholesterol (FER HDL ) (P < 0.0001), and negatively correlated with apolipoprotein AI (apoAI) (P < 0.05) and HDL cholesterol (HDL-C) (P < 0.001). These results suggest that this method is sensitive, reproducible, and not greatly influenced by serum components and added substances, and will be a useful tool in the lipid metabolism study and the risk assessment of CVD.

Simple, fast and reliable liquid chromatographic and spectrophotometric methods for the determination of theophylline in urine, saliva and plasma samples.

PubMed

Charehsaz, Mohammad; Gürbay, Aylin; Aydin, Ahmet; Sahin, Gönül

2014-01-01

In this study, a high-performance liquid chromatographic method (HPLC) and UV spectrophotometric method were developed, validated and applied for the determination of theophylline in biological fluids. Liquid- liquid extraction is performed for isolation of the drug and elimination of plasma and saliva interferences. Urine samples were applied without any extraction. The chromatographic separation was achieved on a C18 column by using 60:40 methanol:water as mobile phase under isocratic conditions at a flow rate of 0.75 mL/min with UV detection at 280 nm in HPLC method. UV spectrophotometric analysis was performed at 275 nm. the limit of quantification: 1.1 µg/mL for urine, 1.9 µg/mL for saliva, 3.1 µg/mL for plasma; recovery: 94.85% for plasma, 100.45% for saliva, 101.39% for urine; intra-day precision: 0.22-2.33%, inter-day precision: 3.17-13.12%. Spectrophotometric analysis results were as follows: the limit of quantitation: 5.23 µg/mL for plasma, 8.7 µg/mL for urine; recovery: 98.27% for plasma, 95.25% for urine; intra-day precision: 2.37 - 3.00%, inter-day precision: 5.43-7.91%. It can be concluded that this validated HPLC method is easy, precise, accurate, sensitive and selective for determination of theophylline in biological samples. Also spectrophotometric analysis can be used where it can be applicable.

Simultaneous Determination of Ten Constituents in Chaiqin Qingning Capsule by High-performance Liquid Chromatography Coupled with Triple-quadrupole Mass Spectrometry

PubMed Central

Li, Ting Yu; Huo, Xiao Kui; Zheng, Lu; Wang, Chao; Cong, Hai Jian; Xiang, Ting; Zhang, Lin; Zhang, Bao Jing; Huang, Shan Shan; Wu, Bin; Li, Xin Yu

2017-01-01

Background: Chaiqin Qingning Capsule (CQQNC) was a prescription of Traditional Chinese Medicine with the effects of clearing away heat and removing toxin, harmonizing the exterior and interior, it was widely used in Asian, for example, China and Japan, different batches of the raws materials and different processing time may be the vital factor which raised a challenge to control the quality of the CQQNC. Experimental Methods: In this experiment, a high-performance liquid chromatography-mass spectrometry/MS (HPLC-MS/MS) method was developed to simultaneously determine ten bioactive components for the quality control of CQQNC. Chromatographic separation was achieved using an XBridge BEH C18 column (150 mm × 4.6 mm, 2.5 μm) with a mobile phase composed of 10 mm aqueous ammonium acetate and acetonitrile using a gradient elution in 20 min. This study was conducted by multiple reaction monitoring mode through electrospray ionization resource with a negative ionization mode. Results: The established method was validated with good performance of precision, accuracy, stability, and reproducibility and was utilized to simultaneously quantify ten constituents of CQQNC obtained from seven different batches. Conclusion: It is the first time to report the rapid and simultaneous analysis of the ten compounds in CQQNC by HPLC-MS/MS and apply to determine 10 constituents in 7 batches of CQQNC bought from drug store in china. This method could be considered as good quality criteria to control the quality of CQQNC. SUMMARY In this paper, a simple, specific, and rapid high-performance liquid chromatogram coupled with triple-quadrupole mass spectrometry method for simultaneous quantification of ten constituents in Chaiqin Qingning Capsule has been developed for the first time. This method could be considered as good quality criteria to control the quality of CQQNC. Abbreviations used: CHM: Chinese herbal medicine; TCM: Traditional Chinese Medicine; CQQNC: Triple-quadrupole mass spectrometry Chaiqin Qingning Capsules; HPLC–MS/MS: High liquid chromatography equipped with tandem mass spectrometry; ESI: Electrospray ionization; DP: Declustering potential; CE: Collision energy; RSD: Relative standard deviation; LOD: Limit of detection; LOQ: Limit of quantity. PMID:29200714

A novel automated hydrophilic interaction liquid chromatography method using diode-array detector/electrospray ionization tandem mass spectrometry for analysis of sodium risedronate and related degradation products in pharmaceuticals.

PubMed

Bertolini, Tiziana; Vicentini, Lorenza; Boschetti, Silvia; Andreatta, Paolo; Gatti, Rita

2014-10-24

A simple, sensitive and fast hydrophilic interaction liquid chromatography (HILIC) method using ultraviolet diode-array detector (UV-DAD)/electrospray ionization tandem mass spectrometry was developed for the automated high performance liquid chromatography (HPLC) determination of sodium risedronate (SR) and its degradation products in new pharmaceuticals. The chromatographic separations were performed on Ascentis Express HILIC 2.7μm (150mm×2.1mm, i.d.) stainless steel column (fused core). The mobile phase consisted of formate buffer solution (pH 3.4; 0.03M)/acetonitrile 42:58 and 45:55 (v/v) for granules for oral solution and effervescent tablet analysis, respectively, at a flow-rate of 0.2mL/min, setting the wavelength at 262nm. Stability characteristics of SR were evaluated by performing stress test studies. The main degradation product formed under oxidation conditions corresponding to sodium hydrogen (1-hydroxy-2-(1-oxidopyridin-3-yl)-1-phosphonoethyl)phosphonate was characterized by high performance liquid chromatography-electrospray ionization-mass tandem mass spectrometry (HPLC-ESI-MS/MS). The validation parameters such as linearity, sensitivity, accuracy, precision and selectivity were found to be highly satisfactory. Linear responses were observed in standard and in fortified placebo solutions. Intra-day precision (relative standard deviation, RSD) was ≤1.1% for peak area and ≤0.2% for retention times (tR) without significant differences between intra- and inter-day data. Recovery studies showed good results for all the examined compounds (from 98.7 to 101.0%) with RSD ranging from 0.6 to 0.7%. The limits of detection (LOD) and quantitation (LOQ) were 1 and 3ng/mL, respectively. The high stability of standard and sample solutions at room temperature means an undoubted advantage of the method allowing the simultaneous preparation of many samples and consecutive chromatographic analyses by using an autosampler. The developed stability indicating method is suitable for the quality control of SR in new and commercial pharmaceutical formulations. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous Determination of Ten Constituents in Chaiqin Qingning Capsule by High-performance Liquid Chromatography Coupled with Triple-quadrupole Mass Spectrometry.

PubMed

Li, Ting Yu; Huo, Xiao Kui; Zheng, Lu; Wang, Chao; Cong, Hai Jian; Xiang, Ting; Zhang, Lin; Zhang, Bao Jing; Huang, Shan Shan; Wu, Bin; Li, Xin Yu

2017-01-01

Chaiqin Qingning Capsule (CQQNC) was a prescription of Traditional Chinese Medicine with the effects of clearing away heat and removing toxin, harmonizing the exterior and interior, it was widely used in Asian, for example, China and Japan, different batches of the raws materials and different processing time may be the vital factor which raised a challenge to control the quality of the CQQNC. In this experiment, a high-performance liquid chromatography-mass spectrometry/MS (HPLC-MS/MS) method was developed to simultaneously determine ten bioactive components for the quality control of CQQNC. Chromatographic separation was achieved using an XBridge BEH C18 column (150 mm × 4.6 mm, 2.5 μm) with a mobile phase composed of 10 mm aqueous ammonium acetate and acetonitrile using a gradient elution in 20 min. This study was conducted by multiple reaction monitoring mode through electrospray ionization resource with a negative ionization mode. The established method was validated with good performance of precision, accuracy, stability, and reproducibility and was utilized to simultaneously quantify ten constituents of CQQNC obtained from seven different batches. It is the first time to report the rapid and simultaneous analysis of the ten compounds in CQQNC by HPLC-MS/MS and apply to determine 10 constituents in 7 batches of CQQNC bought from drug store in china. This method could be considered as good quality criteria to control the quality of CQQNC. In this paper, a simple, specific, and rapid high-performance liquid chromatogram coupled with triple-quadrupole mass spectrometry method for simultaneous quantification of ten constituents in Chaiqin Qingning Capsule has been developed for the first time. This method could be considered as good quality criteria to control the quality of CQQNC. Abbreviations used: CHM: Chinese herbal medicine; TCM: Traditional Chinese Medicine; CQQNC: Triple-quadrupole mass spectrometry Chaiqin Qingning Capsules; HPLC-MS/MS: High liquid chromatography equipped with tandem mass spectrometry; ESI: Electrospray ionization; DP: Declustering potential; CE: Collision energy; RSD: Relative standard deviation; LOD: Limit of detection; LOQ: Limit of quantity.

Spectral properties of thermal fluctuations on simple liquid surfaces below shot-noise levels.

PubMed

Aoki, Kenichiro; Mitsui, Takahisa

2012-07-01

We study the spectral properties of thermal fluctuations on simple liquid surfaces, sometimes called ripplons. Analytical properties of the spectral function are investigated and are shown to be composed of regions with simple analytic behavior with respect to the frequency or the wave number. The derived expressions are compared to spectral measurements performed orders of magnitude below shot-noise levels, which is achieved using a novel noise reduction method. The agreement between the theory of thermal surface fluctuations and the experiment is found to be excellent, elucidating the spectral properties of the surface fluctuations. The measurement method requires relatively only a small sample both spatially (few μm) and temporally (~20 s). The method also requires relatively weak light power (~0.5 mW) so that it has a broad range of applicability, including local measurements, investigations of time-dependent phenomena, and noninvasive measurements.

High-performance liquid chromatography as a technique to determine protein adsorption onto hydrophilic/hydrophobic surfaces.

PubMed

Huang, Tongtong; Anselme, Karine; Sarrailh, Segolene; Ponche, Arnaud

2016-01-30

The purpose of this study is to evaluate the potential of simple high performance liquid chromatography (HPLC) setup for quantification of adsorbed proteins on various type of plane substrates with limited area (<3 cm(2)). Protein quantification was investigated with a liquid chromatography chain equipped with a size exclusion column or a reversed-phase column. By evaluating the validation of the method according to guidelines of the International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH), all the results obtained by HPLC were reliable. By simple adsorption test at the contact of hydrophilic (glass) and hydrophobic (polydimethylsiloxane: PDMS) surfaces, kinetics of adsorption were determined and amounts of adsorbed bovine serum albumin, myoglobin and lysozyme were obtained: as expected for each protein, the amount adsorbed at the plateau on glass (between 0.15 μg/cm(2) and 0.4 μg/cm(2)) is lower than for hydrophobic PDMS surfaces (between 0.45 μg/cm(2) and 0.8 μg/cm(2)). These results were consistent with bicinchoninic acid protein determination. According to ICH guidelines, both Reversed Phase and Size Exclusion HPLC can be validated for quantification of adsorbed protein. However, we consider the size exclusion approach more interesting in this field because additional informations can be obtained for aggregative proteins. Indeed, monomer, dimer and oligomer of bovine serum albumin (BSA) were observed in the chromatogram. On increasing the temperature, we found a decrease of peak intensity of bovine serum albumin as well as the fraction of dimer and oligomer after contact with PDMS and glass surface. As the surface can act as a denaturation parameter, these informations can have a huge impact on the elucidation of the interfacial behavior of protein and in particular for aggregation processes in pharmaceutical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

NASA Technical Reports Server (NTRS)

Belieres, Jean-Philippe

2004-01-01

There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research Center during this summer is to develop and characterize proton exchange membranes doped with ionic liquids. The main techniques used to characterize these materials are: Impedance Spectroscopy, NMR, DSC, TGA, DMA, IR, and SEM ...

Evaluation of on-board hydrogen storage methods for hypersonic vehicles

NASA Technical Reports Server (NTRS)

Akyurtlu, Ates; Akyurtlu, J. F.; Adeyiga, A. A.; Perdue, Samara; Northam, G. B.

1989-01-01

Hydrogen is the foremost candidate as a fuel for use in high speed transport. Since any aircraft moving at hypersonic speeds must have a very slender body, means of decreasing the storage volume requirements below that for liquid hydrogen are needed. The total performance of the hypersonic plane needs to be considered for the evaluation of candidate fuel and storage systems. To accomplish this, a simple model for the performance of a hypersonic plane is presented. To allow for the use of different engines and fuels during different phases of flight, the total trajectory is divided into three phases: subsonic-supersonic, hypersonic and rocket propulsion phase. The fuel fraction for the first phase is found be a simple energy balance using an average thrust to drag ratio for this phase. The hypersonic flight phase is investigated in more detail by taking small altitude increments. This approach allowed the use of flight profiles other than the constant dynamic pressure flight. The effect of fuel volume on drag, structural mass and tankage mass was introduced through simplified equations involving the characteristic dimension of the plane. The propellant requirement for the last phase is found by employing the basic rocket equations. The candidate fuel systems such as the cryogenic fuel combinations and solid and liquid endothermic hydrogen generators are first screened thermodynamically with respect to their energy densities and cooling capacities and then evaluated using the above model.

The Physics Teacher: The Four States of Matter--Solid, Squishy, Liquid and Gas

ERIC Educational Resources Information Center

Clark, Roy W.

2007-01-01

The Physics Teacher provides introductory physics education at the high school and university levels and some of its articles are of interest to chemists. One such article points out that several substances used in the kitchen and bathrooms are not simple liquids or solids but are squishy substances, which include mayonnaise, shaving cream,…

A low-threshold, high-efficiency microfluidic waveguide laser.

PubMed

Vezenov, Dmitri V; Mayers, Brian T; Conroy, Richard S; Whitesides, George M; Snee, Preston T; Chan, Yinthai; Nocera, Daniel G; Bawendi, Moungi G

2005-06-29

This communication describes a long (1 cm), laser-pumped, liquid core-liquid cladding (L2) waveguide laser. This device provides a simple, high intensity, tunable light source for microfludic applications. Using a core solution of 2 mM rhodamine 640 perchlorate, optically pumped by a frequency-doubled Nd:YAG laser, we found that the threshold for lasing was as low as 22 muJ (16-ns pulse length) and had a slope efficiency up to 20%. The output wavelength was tunable over a 20-nm range by changing the ratio of solvent components (dimethyl sulfoxide and methanol) in the liquid core.

[Determination of morroniside concentration in beagle plasma and its pharmacokinetics by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Xiong, Shan; Li, Jinglai; Zhu, Xiuqing; Wang, Xiaoying; Lü, Guiyuan; Zhang, Zhenqing

2014-03-01

A sensitive, simple and specific high performance liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) method was developed for the determination of morroniside in the plasma of beagles administered via intragastric (ig) doses of morroniside. The method employed paeoniflorin as the internal standard and extracted by simple protein precipitation. The separation was achieved using an Inertsil ODS-SP column (50 mm x 2.1 mm, 5 microm) with mobile phases of 1 mmol/L sodium formate aqueous solution and acetonitrile (gradient elution) at a flow rate of 0.4 mL/min. The detection was accomplished by a mass spectrometer using multiple reaction monitoring (MRM) in positive mode. Pharmacokinetic parameters were fitted by software DAS 2.0. The methodological study showed a good linear relationship of 2-5 000 microg/L (r = 0.996 6) with a sensitivity of 2 microg/L as the limit of quantification. The precision, accuracy, mean recoveries and the matrix effects were satisfied with the requirements of biological sample measurement. The method described above was successfully applied to the pharmacokinetic study of morroniside in the beagle plasma samples. The area under the plasma concentration-time curves (AUC(0-infinity)) of morroniside after single ig administration doses of 5, 15 and 45 mg/kg were (1 631.20 +/- 238.50), (3 984.05 +/- 750.38) and (10 397.64 +/- 3 156.34) microg/L x h. The relationship between dose and AUC showed a good linearity. The pharmacokinetic property of morroniside was proposed to be linear pharmacokinetics.

Non-ionic detergent Triton X-114 Based vortex- synchronized matrix solid-phase dispersion method for the simultaneous determination of six compounds with various polarities from Forsythiae Fructus by ultra high-performance liquid chromatography.

PubMed

Du, Kunze; Li, Jin; Tian, Fei; Chang, Yan-Xu

2018-02-20

A simple nonionic detergent - based vortex- synchronized matrix solid-phase dispersion (ND-VSMSPD) method was developed to extract bioactive compounds in Forsythiae Fructus coupled with ultra high-performance liquid chromatography (UHPLC). Nonionic detergent Triton 114 was firstly used as a green elution reagent in vortex- synchronized MSPD procedure. The optimum parameters were investigated to attain the best results, including Florisil as sorbent, 2mL 10% (v/v) nonionic detergent Triton X-114 as the elution reagent, 1:1 of sample/sorbent ratio, grinding for 3min, and whirling for 2min. The recoveries of the six compounds in Forsythiae Fructus were in the range of 95-104% (RSD <4.6%) and the method displayed a good linearity within the range of 0.08-20μgmL -1 for caffeic acid, 0.6-150μgmL -1 for forsythoside A, 0.4-100μgmL -1 phillyrin, 0.2-50μgmL -1 for quercetin, isorhamnetin and arctigenin (r≥0.999). It was proved that the extraction yields of almost all compounds attained by the established vortex- synchronized MSPD, which required lower sample, reagent and time, were higher than the normal MSPD and the traditional ultrasonic-assisted extraction. Consequently, this developed vortex- synchronized MSPD coupled with simple UHPLC method could be efficiently applies to extract and analyze the target compounds in real Forsythiae Fructus samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of ionic liquids in vacuum microwave-assisted extraction followed by macroporous resin isolation of three flavonoids rutin, hyperoside and hesperidin from Sorbus tianschanica leaves.

PubMed

Gu, Huiyan; Chen, Fengli; Zhang, Qiang; Zang, Jing

2016-03-01

Rutin, hyperoside and hesperidin were effectively extracted from Sorbus tianschanica leaves by an ionic liquid vacuum microwave-assisted method. A series of ionic liquids with various anions and alkyl chain length of the cations were studied and the extraction was performed in [C6mim][BF4] aqueous solution. After optimization by a factorial design and response surface methodology, total extraction yield of 2.37mg/g with an error of 0.12mg/g (0.71±0.04mg/g, 1.18±0.06mg/g and 0.48±0.02 for rutin, hyperoside and hesperidin, respectively) was achieved under -0.08MPa for vacuum, 19min and 420W for microwave irradiation time and power, and 15mL/g for liquid-solid ratio. The proposed method here is more efficient and needs a shorter extraction time for rutin, hyperoside and hesperidin from S. tianschanica leaves than reference extraction techniques. In stability studies performed with standard rutin, hyperoside and hesperidin, the target analytes were stable under the optimum conditions. The proposed method had a high reproducibility and precision. In addition, separation of rutin, hyperoside and hesperidin from [C6mim][BF4] extraction solution was completed effectively by AB-8 macroporous resin adsorption and desorption process. Ionic liquid vacuum microwave-assisted extraction is a simple, rapid and efficient sample extraction technique. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface Tension Gradients Induced by Temperature: The Thermal Marangoni Effect

ERIC Educational Resources Information Center

Gugliotti, Marcos; Baptisto, Mauricio S.; Politi, Mario J.

2004-01-01

Surface tensions gradients were generated in a thin liquid film because of the local increase in temperature, for demonstration purposes. This is performed using a simple experiment and allows different alternatives for heat generation to be used.

Sensitive determination of three aconitum alkaloids and their metabolites in human plasma by matrix solid-phase dispersion with vortex-assisted dispersive liquid-liquid microextraction and HPLC with diode array detection.

PubMed

Wang, Xiaozhong; Li, Xuwen; Li, Lanjie; Li, Min; Liu, Ying; Wu, Qian; Li, Peng; Jin, Yongri

2016-05-01

A simple and sensitive method for determination of three aconitum alkaloids and their metabolites in human plasma was developed using matrix solid-phase dispersion combined with vortex-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography with diode array detection. The plasma sample was directly purified by matrix solid-phase dispersion and the eluate obtained was concentrated and further clarified by vortex-assisted dispersive liquid-liquid microextraction. Some important parameters affecting the extraction efficiency, such as type and amount of dispersing sorbent, type and volume of elution solvent, type and volume of extraction solvent, salt concentration as well as sample solution pH, were investigated in detail. Under optimal conditions, the proposed method has good repeatability and reproducibility with intraday and interday relative standard deviations lower than 5.44 and 5.75%, respectively. The recoveries of the aconitum alkaloids ranged from 73.81 to 101.82%, and the detection limits were achieved within the range of 1.6-2.1 ng/mL. The proposed method offered the advantages of good applicability, sensitivity, simplicity, and feasibility, which makes it suitable for the determination of trace amounts of aconitum alkaloids in human plasma samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selective separation of americium from europium using 2,9-bis(triazine)-1,10-phenanthrolines in ionic liquids: a new twist on an old story

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Neil J.; Dehaudt, Jeremy; Bryantsev, Vyacheslav S.

Bis-triazine phenanthrolines have shown great promise for f-block metal separations, attributable to their highly preorganized structure, nitrogen donors, and more enhanced covalent bonding with actinides over lanthanides. However, their limited solubility in traditional solvents remains a technological bottleneck. Here in this paper we report our recent work using a simple 2,9-bis(triazine)-1,10-phenanthroline (Me-BTPhen) dissolved in an ionic liquid (IL), demonstrating the efficacy of IL extraction systems for the selective separation of americium from europium, achieving separation factors in excess of 7500 and selectively removing up to 99% of the americium. Characterization of the coordination environment was performed using a combination ofmore » X-ray absorption fine structure spectroscopy (XAFS) and density functional theory (DFT) calculations.« less

Liquid chromatographic determination of 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one in human plasma with fluorescence detection.

PubMed

Cheng, H; Pittman, K A; Dandekar, K A

1987-12-01

A simple and sensitive assay for quantitating 9-methyl-3-(1H-tetrazol-5-yl)-4H-pyrido[1,2-a]pyrimidin-4-one (1; BMY 26517) in human plasma was developed using high-performance liquid chromatography with fluorescence detection. The method involves precipitation of protein and reversed-phase chromatography. The method is linear in the range of 4.3-429 ng/mL of 1, and the limit of detection is 0.4 ng/mL. The day-to-day precision values of this method at 25.7 and 386 ng/mL are 2.1 and 2.6%, respectively. The day-to-day accuracy values at these concentrations are 99.7 and 99.8%, respectively. The recovery of 1 is 98.3%.

Selective separation of americium from europium using 2,9-bis(triazine)-1,10-phenanthrolines in ionic liquids: a new twist on an old story

DOE PAGES

Williams, Neil J.; Dehaudt, Jeremy; Bryantsev, Vyacheslav S.; ...

2017-02-10

Bis-triazine phenanthrolines have shown great promise for f-block metal separations, attributable to their highly preorganized structure, nitrogen donors, and more enhanced covalent bonding with actinides over lanthanides. However, their limited solubility in traditional solvents remains a technological bottleneck. Here in this paper we report our recent work using a simple 2,9-bis(triazine)-1,10-phenanthroline (Me-BTPhen) dissolved in an ionic liquid (IL), demonstrating the efficacy of IL extraction systems for the selective separation of americium from europium, achieving separation factors in excess of 7500 and selectively removing up to 99% of the americium. Characterization of the coordination environment was performed using a combination ofmore » X-ray absorption fine structure spectroscopy (XAFS) and density functional theory (DFT) calculations.« less

Rapid determination of minoxidil in human plasma using ion-pair HPLC.

PubMed

Zarghi, A; Shafaati, A; Foroutan, S M; Khoddam, A

2004-10-29

A rapid, simple and sensitive ion-pair high-performance liquid chromatography (HPLC) method has been developed for quantification of minoxidil in plasma. The assay enables the measurement of minoxidil for therapeutic drug monitoring with a minimum detectable limit of 0.5 ng ml(-1). The method involves simple, one-step extraction procedure and analytical recovery was complete. The separation was performed on an analytical 150 x 4.6 mm i.d. microbondapak C18 column. The wavelength was set at 281 nm. The mobile phase was a mixture of 0.01 M sodium dihydrogen phosphate buffer and acetonitrile (60:40, v/v) containing 2.5 mM sodium dodecyl sulphate adjusted to pH 3.5 at a flow rate of 1 ml/min. The column temperature was set at 50 degrees C. The calibration curve was linear over the concentration range 2-100 ng ml(-1). The coefficients of variation for inter-day and intra-day assay were found to be less than 8%.

Development of a sensitive high-performance liquid chromatographic method with simple extraction for simultaneous determination of huperzine A and huperzine B in the species containing lycopodium alkaloids.

PubMed

Zhang, Yanqing; Xie, Junbo; Chen, Wen-Qian; Zhou, Tian-Yan; Lu, Wei

2009-01-01

A sensitive HPLC method with simple extraction was developed for simultaneous determination of huperzine A (HupA) and huperzine B (HupB) in Huperzia serrata, H. crispata, H. miyoshiana, and Lycopodiastrum casuarinoides. In order to avoid conventional multiple-step and time-consuming sample preparation methods, direct reflux extraction with alkaline chloroform was adopted. The quantitative determination was conducted by reversed-phase HPLC with a photodiode array detector set at 308 nm. Separation was performed on a Luna C18 column (250 x 4.6 mm id, 5 microm) with methanol-0.2% aqueous acetic acid (18 + 82, v/v) mobile phase. The method was validated for accuracy, reproducibility, precision, and limits of detection and quantification. Quantification of the two active compounds in the samples was performed by this newly developed method, and the content of HupA and HupB varied substantially among four different species. The satisfactory results indicated that the developed method can readily be utilized for quality control of the species of Huperziaceae and Lycopodiaceae containing the two compounds.

Simultaneous determination of thirteen flavonoids from Xiaobuxin-Tang extract using high-performance liquid chromatography coupled with electrospray ionization mass spectrometry.

PubMed

Cen, Meifeng; Ruan, Jinxiu; Huang, Lihua; Zhang, Zhenqing; Yu, Nengjiang; Zhang, Youzhi; Cheng, Xuange; Xiong, Xiaohong; Wang, Guixiang; Zang, Linquan; Wang, Sujun

2015-11-10

A simple and reliable high performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS) analysis method was established to simultaneously determine thirteen flavonoids of Xiaobuxing-Tang in intestine perfusate, namely onpordin, 3'-O-methylorobol, glycitein, patuletin, genistein, luteolin, quercetin, nepitrin, quercimeritrin, daidzin, patulitrin, quercetagitrin and 3-glucosylisorhamnetin. Detection was performed on a quadrupole mass spectrometer equipped with an electrospray ionization (ESI) source operating in negative ionization mode. Negative ion ESI was used to form deprotonated molecules at m/z 315 for onpordin, m/z 299 for 3'-O-methylorobol, m/z 283 for glycitein, m/z 331 for patuletin, m/z 269 for genistein, m/z 285 for luteolin, m/z 301 for quercetin, m/z 477 for nepitrin, m/z 463 for quercimeritrin, m/z 461 for daidzin, m/z 493 for patulitrin, m/z 479 for quercetagitrin, m/z 477 for 3-glucosylisorhamnetin and m/z 609.2 for rutin. The linearity, sensitivity, selectivity, repeatability, accuracy, precision, recovery and matrix effect of the assay were evaluated. The proposed method was successfully applied to simultaneous determination of these thirteen flavonoids, and using this method, the intestinal absorption profiles of thirteen flavonoids were preliminarily predicted. Copyright © 2015 Elsevier B.V. All rights reserved.

[Determination of antibiotics in oral hygiene products by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Zhou, Weijun; Xie, Zhengfu; Shao, Linzhi

2012-07-01

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/ MS) method was developed for simultaneous determination of 13 antibiotics in oral hygiene products, including five tetracyclines, three macrolides, two quinolones, one beta-lactam and two lincosamides. The sample was extracted with 0.1% (volume percentage, same hereinafter) formic acid-acetonitrile (95:5, v/v), then centrifuged, filtered and diluted. The target compounds were separated on a C18 column (150 mm x 2.1 mm, 5 microm) with a gradient elution of 0. 1% formic acid and acetonitrile as the mobile phases, and detected by tandem mass spectrometry in positive electrospray ionization and multiple reaction monitoring (MRM) mode. The quantification of 13 antibiotics was performed by the external standard method. The calibration curves showed good linearity in the range of 5.0-50.0 microg/L with detection limits of 10.0 mg/kg. The recoveries of antibiotics in mouthwash and toothpaste samples at the three spiked levels of 10, 20 and 100 mg/kg were in the range of 80.1%-115% with the relative standard deviations in the range of 0.94%-8.69%. This method is accurate, reliable, simple, and suitable for the analysis of antibiotics in oral hygiene products.

[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.

Effective extraction and simultaneous determination of Sudan dyes from tomato sauce and chili-containing foods using magnetite/reduced graphene oxide nanoparticles coupled with high-performance liquid chromatography.

PubMed

Zhang, Ming-Yue; Wang, Man-Man; Hao, Yu-Lan; Shi, Xin-Ran; Wang, Xue-Sheng

2016-05-01

A simple, effective, and robust magnetic solid-phase extraction method was developed using magnetite/reduced graphene oxide nanoparticles as the adsorbent for the simultaneous determination of Sudan dyes (I, II, III, and IV) in foodstuffs. The magnetite/reduced graphene oxide nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. The extraction parameters including extraction time, elution solution, and elution time and volume were investigated in detail. Such magnetite/reduced graphene oxide nanoparticles based magnetic solid-phase extraction in combination with high-performance liquid chromatography and variable wavelength detection gave the detection limits of 3-6 μg/kg for Sudan I-IV in chili sauce, tomato sauce, chili powder, and chili flake samples. The recoveries were 79.6-108% at three spiked levels with the intra- and inter-day relative standard deviations of 1.2-8.6 and 4.5-9.6%, respectively. The feasibility was further performed by a comparison with commercial alumina-N. This method is suitable for the routine analysis of Sudan dyes due to its sensitivity, simplicity, and low cost. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Validation of a high-performance liquid chromatographic method with UV detection for the determination of ethopabate residues in poultry liver.

PubMed

Granja, Rodrigo H M M; Niño, Alfredo M Montes; Zucchetti, Roberto A M; Niño, Rosario E Montes; Salerno, Alessandro G

2008-01-01

Ethopabate is frequently used in the prophylaxis and treatment of coccidiosis in poultry. Residues of this drug in food present a potential risk to consumers. A simple, rapid, and sensitive column high-performance liquid chromatographic (HPLC) method with UV detection for determination of ethopabate in poultry liver is presented. The drug is extracted with acetonitrile. After evaporation, the residue is dissolved with an acetone-hexane mixture and cleaned up by solid-phase extraction using Florisil columns. The analyte is then eluted with methanol. LC analysis is carried out on a C18 5 microm Gemini column, 15 cm x 4.6 mm. Ethopabate is quantified by means of UV detection at 270 nm. Parameters such as decision limit, detection capability, precision, recovery, ruggedness, and measurement uncertainty were calculated according to method validation guidelines provided in 2002/657/EC and ISO/IEC 17025:2005. Decision limit and detection capability were determined to be 2 and 3 microg/kg, respectively. Average recoveries from poultry samples fortified with 10, 15, and 20 microg/kg levels of ethopabate were 100-105%. A complete statistical analysis was performed on the results obtained, including an estimation of the method uncertainty. The method is to be implemented into Brazil's residue monitoring and control program for ethopabate.

Performance of a pentafluorophenylpropyl stationary phase for the electrospray ionization high-performance liquid chromatography-mass spectrometry-mass spectrometry assay of cocaine and its metabolite ecgonine methyl ester in human urine.

PubMed

Needham, S R; Jeanville, P M; Brown, P R; Estape, E S

2000-10-01

A pentafluorophenylpropyl (PFPP) bonded silica column has been used for the high-performance liquid chromatography-electrospray ionization-mass spectrometry-mass spectrometry assay (HPLC-ESI-MS-MS) of cocaine (COC) and its metabolite, ecgonine methyl ester (EME) in human urine. COC and EME were used as model basic solutes to demonstrate that a PFPP phase yields excellent results for the assay and validation of drugs in biological fluids. The assay was linear over three orders of magnitude (1.0-1000 ng/ml) and precision and accuracy of the assay was 4 and 15%, respectively. The limit of detection (LOD) for COC and EME was 1.6 and 2.8 pg on column, respectively. In addition, only a simple 1:10 dilution of the urine was necessary for the sample preparation procedure thus saving time on a laborious extraction step. The major advantage of the PFPP phase was the enhancement of the ESI-MS signal by providing good retention and good peak shape of COC and EME with a mobile phase of 90% acetonitrile. The MS signal for COC was a factor of 12 times greater on the PFPP phase than on the C18 phase.

[Simultaneous determination of four common nonprotein nitrogen substances in urine by high performance liquid chromatography].

PubMed

Ma, Yuhua; Huang, Dongqun; Zhang, Rui; Xu, Shiru; Feng, Shun

2013-11-01

A high performance liquid chromatographic (HPLC) method was proposed to simultaneously determine four common nonprotein nitrogen substances, including creatine (Cr), creatinine (Cn), uric acid (Ua) and pseudouridine (Pu) in urine. After proteins being removed by acetone precipitation method, freeze drying and redissolving, the urine samples were analyzed by HPLC. Chromatographic separation was performed on a Waters RP18 Column (150 mm x 4.60 mm, 3.5 microm) in gradient elution mode using 10.0 mmol/L KH2PO4 solution (pH 4.78) and acetonitrile as mobile phases at a flow rate of 0.8 mL/min. The samples were detected at 220 nm. Rapid separation was achieved within 7 min. Under the optimized conditions, good linearities of four common nonprotein nitrogen substances were obtained in the range of 0.1-250 mg/L. The detection limits were 9.31 (Cr), 26.19 (Cn), 4.70 (Ua), an 6.30 (Pu) microg/L and the recoveries were in the range of 81%-111% with the relative standar deviations of 0.23%-2.78% (n = 3). The results demonstrate that this method is simple, rapid and accurate with good reproducibility, and can provide early diagnosis and preliminary judgment for type 2 diabetes mellitus (T2DM) patients with renal damage.

Simultaneous determination of sulfonamides, penicillins and coccidiostats in pork by high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Nebot, C; Regal, P; Miranda, J; Cepeda, A; Fente, C

2012-05-01

Veterinary drugs are widely and legally used to treat and prevent disease in livestock. However, drugs are also used illegally as growth-promoting agents. To protect the health of consumers, maximum residue limits (MRL) in food of animal origin have been established and are listed in Regulation 37/2010. According to this regulation, more than 300 drugs need to be controlled regularly in laboratories for residues of veterinary drugs. A cost-effective analytical method is very important and explains why the development of multi-residual methods is becoming popular in laboratories. The aim of this work is to describe a simple, rapid and economical high-performance liquid chromatography-tandem mass spectrometry method for the simultaneous identification and quantification of 21 veterinary drugs in pork muscle samples. The sample clean-up procedure is performed with acidified dichloromethane and does not require solid phase extraction. The method is applicable to nine sulfonamides and seven coccidiostats identified within 36 min. Calculated relevant validation parameters such as recoveries (from 72.to 126 %), intra-precision and intermediate precision (relative standard deviation below 40 %) and decision limits (below 7 µg Kg(-1)) were within acceptable range and in compliance with the requirements of Commission Decision 2002/657/EC. © The Author [2012]. Published by Oxford University Press. All rights reserved.

Comparison of liquid-state anomalies in Stillinger-Weber models of water, silicon, and germanium

NASA Astrophysics Data System (ADS)

Dhabal, Debdas; Chakravarty, Charusita; Molinero, Valeria; Kashyap, Hemant K.

2016-12-01

We use molecular dynamics simulations to compare and contrast the liquid-state anomalies in the Stillinger-Weber models of monatomic water (mW), silicon (Si), and germanium (Ge) over a fairly wide range of temperatures and densities. The relationships between structure, entropy, and mobility, as well as the extent of the regions of anomalous behavior, are discussed as a function of the degree of tetrahedrality. We map out the cascade of density, structural, pair entropy, excess entropy, viscosity, and diffusivity anomalies for these three liquids. Among the three liquids studied here, only mW displays anomalies in the thermal conductivity, and this anomaly is evident only at very low temperatures. Diffusivity and viscosity, on the other hand, show pronounced anomalous regions for the three liquids. The temperature of maximum density of the three liquids shows re-entrant behavior consistent with either singularity-free or liquid-liquid critical point scenarios proposed to explain thermodynamic anomalies. The order-map, which shows the evolution of translational versus tetrahedral order in liquids, is different for Ge than for Si and mW. We find that although the monatomic water reproduces several thermodynamic and dynamic properties of rigid-body water models (e.g., SPC/E, TIP4P/2005), its sequence of anomalies follows, the same as Si and Ge, the silica-like hierarchy: the region of dynamic (diffusivity and viscosity) anomalies encloses the region of structural anomalies, which in turn encloses the region of density anomaly. The hierarchy of the anomalies based on excess entropy and Rosenfeld scaling, on the other hand, reverses the order of the structural and dynamic anomalies, i.e., predicts that the three Stillinger-Weber liquids follow a water-like hierarchy of anomalies. We investigate the scaling of diffusivity, viscosity, and thermal conductivity with the excess entropy of the liquid and find that for dynamical properties that present anomalies there is no universal scaling of the reduced property with excess entropy for the whole range of temperatures and densities. Instead, Rosenfeld's scaling holds for all the three liquids at high densities and high temperatures, although deviations from simple exponential dependence are observed for diffusivity and viscosity at lower temperatures and intermediate densities. The slope of the scaling of transport properties obtained for Ge is comparable to that obtained for simple liquids, suggesting that this low tetrahedrality liquid, although it stabilizes a diamond crystal, is already close to simple liquid behavior for certain properties.

Comparison of liquid-state anomalies in Stillinger-Weber models of water, silicon, and germanium.

PubMed

Dhabal, Debdas; Chakravarty, Charusita; Molinero, Valeria; Kashyap, Hemant K

2016-12-07

We use molecular dynamics simulations to compare and contrast the liquid-state anomalies in the Stillinger-Weber models of monatomic water (mW), silicon (Si), and germanium (Ge) over a fairly wide range of temperatures and densities. The relationships between structure, entropy, and mobility, as well as the extent of the regions of anomalous behavior, are discussed as a function of the degree of tetrahedrality. We map out the cascade of density, structural, pair entropy, excess entropy, viscosity, and diffusivity anomalies for these three liquids. Among the three liquids studied here, only mW displays anomalies in the thermal conductivity, and this anomaly is evident only at very low temperatures. Diffusivity and viscosity, on the other hand, show pronounced anomalous regions for the three liquids. The temperature of maximum density of the three liquids shows re-entrant behavior consistent with either singularity-free or liquid-liquid critical point scenarios proposed to explain thermodynamic anomalies. The order-map, which shows the evolution of translational versus tetrahedral order in liquids, is different for Ge than for Si and mW. We find that although the monatomic water reproduces several thermodynamic and dynamic properties of rigid-body water models (e.g., SPC/E, TIP4P/2005), its sequence of anomalies follows, the same as Si and Ge, the silica-like hierarchy: the region of dynamic (diffusivity and viscosity) anomalies encloses the region of structural anomalies, which in turn encloses the region of density anomaly. The hierarchy of the anomalies based on excess entropy and Rosenfeld scaling, on the other hand, reverses the order of the structural and dynamic anomalies, i.e., predicts that the three Stillinger-Weber liquids follow a water-like hierarchy of anomalies. We investigate the scaling of diffusivity, viscosity, and thermal conductivity with the excess entropy of the liquid and find that for dynamical properties that present anomalies there is no universal scaling of the reduced property with excess entropy for the whole range of temperatures and densities. Instead, Rosenfeld's scaling holds for all the three liquids at high densities and high temperatures, although deviations from simple exponential dependence are observed for diffusivity and viscosity at lower temperatures and intermediate densities. The slope of the scaling of transport properties obtained for Ge is comparable to that obtained for simple liquids, suggesting that this low tetrahedrality liquid, although it stabilizes a diamond crystal, is already close to simple liquid behavior for certain properties.

Extremely simple holographic projection of color images

NASA Astrophysics Data System (ADS)

Makowski, Michal; Ducin, Izabela; Kakarenko, Karol; Suszek, Jaroslaw; Kolodziejczyk, Andrzej; Sypek, Maciej

2012-03-01

A very simple scheme of holographic projection is presented with some experimental results showing good quality image projection without any imaging lens. This technique can be regarded as an alternative to classic projection methods. It is based on the reconstruction real images from three phase iterated Fourier holograms. The illumination is performed with three laser beams of primary colors. A divergent wavefront geometry is used to achieve an increased throw angle of the projection, compared to plane wave illumination. Light fibers are used as light guidance in order to keep the setup as simple as possible and to provide point-like sources of high quality divergent wave-fronts at optimized position against the light modulator. Absorbing spectral filters are implemented to multiplex three holograms on a single phase-only spatial light modulator. Hence color mixing occurs without any time-division methods, which cause rainbow effects and color flicker. The zero diffractive order with divergent illumination is practically invisible and speckle field is effectively suppressed with phase optimization and time averaging techniques. The main advantages of the proposed concept are: a very simple and highly miniaturizable configuration; lack of lens; a single LCoS (Liquid Crystal on Silicon) modulator; a strong resistance to imperfections and obstructions of the spatial light modulator like dead pixels, dust, mud, fingerprints etc.; simple calculations based on Fast Fourier Transform (FFT) easily processed in real time mode with GPU (Graphic Programming).

Effervescence-assisted dispersive solid-phase extraction using ionic-liquid-modified magnetic β-cyclodextrin/attapulgite coupled with high-performance liquid chromatography for fungicide detection in honey and juice.

PubMed

Wu, Xiaoling; Yang, Miyi; Zeng, Haozhe; Xi, Xuefei; Zhang, Sanbing; Lu, Runhua; Gao, Haixiang; Zhou, Wenfeng

2016-11-01

In this study, a simple effervescence-assisted dispersive solid-phase extraction method was developed to detect fungicides in honey and juice. Most significantly, an innovative ionic-liquid-modified magnetic β-cyclodextrin/attapulgite sorbent was used because its large specific surface area enhanced the extraction capacity and also led to facile separation. A one-factor-at-a-time approach and orthogonal design were employed to optimize the experimental parameters. Under the optimized conditions, the entire extraction procedure was completed within 3 min. In addition, the calibration curves exhibited good linearity, and high enrichment factors were achieved for pure water and honey samples. For the honey samples, the extraction efficiencies for the target fungicides ranged from 77.0 to 94.3% with relative standard deviations of 2.3-5.44%. The detection and quantitation limits were in the ranges of 0.07-0.38 and 0.23-1.27 μg/L, respectively. Finally, the developed technique was successfully applied to real samples, and satisfactory results were achieved. This analytical technique is cost-effective, environmentally friendly, and time-saving. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simple and validated UHPLC-MS/MS analysis of nimodipine in plasma and cerebrospinal fluid of patients with subarachnoid haemorrhage.

PubMed

Mohamed, Susan; Riva, Roberto; Contin, Manuela

2016-08-15

We present a simple, fast and validated method for the determination of nimodipine in plasma and cerebrospinal fluid (CSF) of patients with subarachnoid haemorrhage using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Plasma or CSF 250μL aliquots were pretreated with acetonitrile spiked with lacosamide as internal standard. The chromatographic separation was performed on a Fusion (3μm) 50×2.0mm I.D. column with gradient elution of 0.1% (v/v) formic acid in water and 0.1% (v/v) formic acid in acetonitrile at a flow rate of 0.35mL/min. The MS/MS ion transitions were 419.1→343 for nimodipine and 251.1→91 for the internal standard. The linearity was determined from 2.0 to 40.0ng/mL in plasma and 40.0-800.0pg/mL in CSF. The lower limit of quantitation (LLOQ) of nimodipine was 0.4ng/mL in plasma and 40pg/mL in CSF. The mean recovery for nimodipine was ≥75% in plasma and ≥90% in CSF at all three considered concentrations. Intra- and interassay precision and accuracy were ≤15% at all quality control concentrations in plasma and CSF. The method was applied to measure plasma and CSF concentrations of nimodipine in a series of patients with subarachnoid haemorrhage treated with intravenous nimodipine. The present procedure, omitting time-consuming liquid-liquid extraction and drying steps, is faster, simpler and cheaper than published LC-MS/MS analytical methods for nimodipine in plasma and the first validated one for nimodipine in CSF. Copyright © 2016 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).

Determination of Alternaria mycotoxins in wine and juice using ionic liquid modified countercurrent chromatography as a pretreatment method followed by high-performance liquid chromatography.

PubMed

Fan, Chen; Cao, Xueli; Liu, Man; Wang, Wei

2016-03-04

Alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TeA) are some of the main Alternaria mycotoxins that can be found as contaminants in food materials. The objective of this study was to develop a pretreatment method with countercurrent chromatography (CCC) for enrichment and cleanup of trace Alternaria mycotoxins in food samples prior to high-performance liquid chromatography (HPLC) analysis. An Analytical CCC instrument with a column volume 22.5mL was used, and a two-phase solvent system composed of ethyl acetate and water modified with 6% [HOOMIM][Cl] in mass to volume ratio was selected. Under the optimized CCC operation conditions, trace amounts of AOH, AME, and TeA in large volume of liquid sample were efficiently extracted and enriched in the stationary phase, and then eluted out just by reversing the stationary phase as mobile phase in the opposite flowing direction tail-to-head. The enrichment and elution strategies are unique and can be fulfilled online with high enrichment factors (87-114) and high recoveries (81.14-110.94%). The method has been successively applied to the determination of Alternaria mycotoxins in real apple juice and wine samples with the limits of detection (LOD) in the range of 0.03-0.14μgL(-1). Totally 12 wine samples and 15 apple juice samples from the local market were analyzed. The detection rate of AOH and AME in both kinds of the samples were more than 50%, while TeA was found in relatively high level of 1.75-49.61μgL(-1) in some of the apple juice samples. The proposed method is simple, rapid, and sensitive and could also be used for the analysis and monitoring of Alternaria mycotoxin in other food samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Lipidomics by ultrahigh performance liquid chromatography-high resolution mass spectrometry and its application to complex biological samples

PubMed Central

Triebl, Alexander; Trötzmüller, Martin; Hartler, Jürgen; Stojakovic, Tatjana; Köfeler, Harald C

2018-01-01

An improved approach for selective and sensitive identification and quantitation of lipid molecular species using reversed phase chromatography coupled to high resolution mass spectrometry was developed. The method is applicable to a wide variety of biological matrices using a simple liquid-liquid extraction procedure. Together, this approach combines three selectivity criteria: Reversed phase chromatography separates lipids according to their acyl chain length and degree of unsaturation and is capable of resolving positional isomers of lysophospholipids, as well as structural isomers of diacyl phospholipids and glycerolipids. Orbitrap mass spectrometry delivers the elemental composition of both positive and negative ions with high mass accuracy. Finally, automatically generated tandem mass spectra provide structural insight into numerous glycerolipids, phospholipids, and sphingolipids within a single run. Method validation resulted in a linearity range of more than four orders of magnitude, good values for accuracy and precision at biologically relevant concentration levels, and limits of quantitation of a few femtomoles on column. Hundreds of lipid molecular species were detected and quantified in three different biological matrices, which cover well the wide variety and complexity of various model organisms in lipidomic research. Together with a reliable software package, this method is a prime choice for global lipidomic analysis of even the most complex biological samples. PMID:28415015

Lipidomics by ultrahigh performance liquid chromatography-high resolution mass spectrometry and its application to complex biological samples.

PubMed

Triebl, Alexander; Trötzmüller, Martin; Hartler, Jürgen; Stojakovic, Tatjana; Köfeler, Harald C

2017-05-15

An improved approach for selective and sensitive identification and quantitation of lipid molecular species using reversed phase chromatography coupled to high resolution mass spectrometry was developed. The method is applicable to a wide variety of biological matrices using a simple liquid-liquid extraction procedure. Together, this approach combines multiple selectivity criteria: Reversed phase chromatography separates lipids according to their acyl chain length and degree of unsaturation and is capable of resolving positional isomers of lysophospholipids, as well as structural isomers of diacyl phospholipids and glycerolipids. Orbitrap mass spectrometry delivers the elemental composition of both positive and negative ions with high mass accuracy. Finally, automatically generated tandem mass spectra provide structural insight into numerous glycerolipids, phospholipids, and sphingolipids within a single run. Calibration showed linearity ranges of more than four orders of magnitude, good values for accuracy and precision at biologically relevant concentration levels, and limits of quantitation of a few femtomoles on column. Hundreds of lipid molecular species were detected and quantified in three different biological matrices, which cover well the wide variety and complexity of various model organisms in lipidomic research. Together with a software package, this method is a prime choice for global lipidomic analysis of even the most complex biological samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Contactless processing of SiGe-melts in EML under reduced gravity.

PubMed

Luo, Yuansu; Damaschke, Bernd; Schneider, Stephan; Lohöfer, Georg; Abrosimov, Nikolay; Czupalla, Matthias; Samwer, Konrad

2016-01-01

The processing of semiconductors based on electromagnetic levitation is a challenge, because this kind of materials shows a poor electrical conductivity. Here, we report the results of measurements of the thermophysical properties obtained recently from highly doped semiconductors Si 1- x Ge x under microgravity conditions in the framework of parabola flight campaigns. Due to the limited time of about 20 s of microgravity especially Ge-rich samples with low melting temperatures were investigated. The measurements were performed contactlessly by video techniques with subsequent digital image processing. Linear and volume thermal expansion coefficients were measured hereby from image data. An anomaly of volume changes near the solidus temperature is visible. Viscosity and surface tension were determined by the oscillating drop technique using optic and electronic data. It was observed that the alloying of Si into Ge increases the surface tension of the melts. The viscosity is following an Arrhenius equation and shows a crossover temperature which separates simple liquid at high temperatures from cooperative liquid at low temperatures.

Molecularly imprinted membrane extraction combined with high-performance liquid chromatography for selective analysis of cloxacillin from shrimp samples.

PubMed

Du, Wei; Sun, Min; Guo, Pengqi; Chang, Chun; Fu, Qiang

2018-09-01

Nowadays, the abuse of antibiotics in aquaculture has generated considerable problems for food safety. Therefore, it is imperative to develop a simple and selective method for monitoring illegal use of antibiotics in aquatic products. In this study, a method combined molecularly imprinted membranes (MIMs) extraction and liquid chromatography was developed for the selective analysis of cloxacillin from shrimp samples. The MIMs was synthesized by UV photopolymerization, and characterized by scanning electron microscope, Fourier transform infrared spectra, thermo-gravimetric analysis and swelling test. The results showed that the MIMs exhibited excellent permselectivity, high adsorption capacity and fast adsorption rate for cloxacillin. Finally, the method was utilized to determine cloxacillin from shrimp samples, with good accuracies and acceptable relative standard deviation values for precision. The proposed method was a promising alternative for selective analysis of cloxacillin in shrimp samples, due to the easy-operation and excellent selectivity. Copyright © 2018. Published by Elsevier Ltd.

FLIC: High-Throughput, Continuous Analysis of Feeding Behaviors in Drosophila

PubMed Central

Pletcher, Scott D.

2014-01-01

We present a complete hardware and software system for collecting and quantifying continuous measures of feeding behaviors in the fruit fly, Drosophila melanogaster. The FLIC (Fly Liquid-Food Interaction Counter) detects analog electronic signals as brief as 50 µs that occur when a fly makes physical contact with liquid food. Signal characteristics effectively distinguish between different types of behaviors, such as feeding and tasting events. The FLIC system performs as well or better than popular methods for simple assays, and it provides an unprecedented opportunity to study novel components of feeding behavior, such as time-dependent changes in food preference and individual levels of motivation and hunger. Furthermore, FLIC experiments can persist indefinitely without disturbance, and we highlight this ability by establishing a detailed picture of circadian feeding behaviors in the fly. We believe that the FLIC system will work hand-in-hand with modern molecular techniques to facilitate mechanistic studies of feeding behaviors in Drosophila using modern, high-throughput technologies. PMID:24978054

Multidetection of antibiotics in liver tissue by ultra-high-pressure-liquid-chromatography-tandem mass spectrometry.

PubMed

Freitas, Andreia; Barbosa, Jorge; Ramos, Fernando

2015-01-22

A multiresidue quantitative screening method covering 39 antibiotics from 7 different families by ultra-high-pressure-liquid-chromatography-tandem mass spectrometry (UHPLC-MS/MS) is described. Sulfonamides, trimethoprim, tetracyclines, macrolides, quinolones, penicillins and chloramphenicol are simultaneously detected in liver tissue. A simple sample treatment method consisting of extraction with a mixture of acetonitrile and ethylenediaminetetraacetic acid (EDTA) followed by solid-phase extraction (SPE) with a hydrophilic-lipophilic balanced (HLB) cartridge was developed. The methodology was validated, in accordance with Decision 2002/657/EC, by evaluating the following required parameters: decision limit (CCα), detection capability (CCβ), specificity, repeatability and reproducibility. The precision, in terms of the relative standard deviation, was under 22% for all of the compounds, and the recoveries were between 80% and 110%. The CCα and CCβ were determined according to the maximum residue limit (MRL) or the minimum required performance limit (MRPL), when established. Copyright © 2014 Elsevier B.V. All rights reserved.

A Simple Method for Determination of the Density of Granular Materials

ERIC Educational Resources Information Center

Tsutsumanova, G. G.; Kirilov, K. M.; Russev, S. C.

2012-01-01

A simple experiment using low cost equipment for the determination of the density of granular materials, without immersing them in a liquid, is presented. It is based only on the ideal gas state equation, so it is a good experimental task for undergraduate and high school students. (Contains 2 tables and 5 figures.)

Liquid crystal point diffraction interferometer. Ph.D. Thesis - Arizona Univ., 1995

NASA Technical Reports Server (NTRS)

Mercer, Carolyn R.

1995-01-01

A new instrument, the liquid crystal point diffraction-interferometer (LCPDI), has been developed for the measurement of phase objects. This instrument maintains the compact, robust design of Linnik's point diffraction interferometer (PDI) and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with very high data density and with automated data reduction. This dissertation describes the theory of both the PDI and liquid crystal phase control. The design considerations for the LCPDI are presented, including manufacturing considerations. The operation and performance of the LCPDI are discussed, including sections regarding alignment, calibration, and amplitude modulation effects. The LCPDI is then demonstrated using two phase objects: defocus difference wavefront, and a temperature distribution across a heated chamber filled with silicone oil. The measured results are compared to theoretical or independently measured results and show excellent agreement. A computer simulation of the LCPDI was performed to verify the source of observed periodic phase measurement error. The error stems from intensity variations caused by dye molecules rotating within the liquid crystal layer. Methods are discussed for reducing this error. Algorithms are presented which reduce this error; they are also useful for any phase-stepping interferometer that has unwanted intensity fluctuations, such as those caused by unregulated lasers.

Sensitive determination of estrogens in environmental waters treated with polymeric ionic liquid-based stir cake sorptive extraction and liquid chromatographic analysis.

PubMed

Chen, Lei; Mei, Meng; Huang, Xiaojia; Yuan, Dongxing

2016-05-15

A simple, sensitive and environmentally friendly method using polymeric ionic liquid-based stir cake sorptive extraction followed by high performance liquid chromatography with diode array detection (HPLC/DAD) has been developed for efficient quantification of six selected estrogens in environmental waters. To extract trace estrogens effectively, a poly (1-ally-3-vinylimidazolium chloride-co-ethylene dimethacrylate) monolithic cake was prepared and used as the sorbent of stir cake sorptive extraction (SCSE). The effects of preparation conditions of sorbent and extraction parameters of SCSE for estrogens were investigated and optimized. Under optimal conditions, the developed method showed satisfactory analytical performance for targeted analytes. Low limits of detection (S/N=3) and quantification limits (S/N=10) were achieved within the range of 0.024-0.057 µg/L and 0.08-0.19 µg/L, respectively. Good linearity of method was obtained for analytes with the correlation coefficients (R(2)) above 0.99. At the same time, satisfactory method repeatability and reproducibility was achieved in terms of intra- and inter-day precisions, respectively. Finally, the established SCSE-HPLC/DAD method was successfully applied for the determination of estrogens in different environmental water samples. Recoveries obtained for the determination of estrogens in spiked samples ranged from 71.2% to 108%, with RSDs below 10% in all cases. Copyright © 2016 Elsevier B.V. All rights reserved.

Simple and rapid determination of norethindrone in human plasma by supported liquid extraction and ultra performance liquid chromatography with tandem mass spectrometry.

PubMed

Gong, Zhilong; Chandler, Kiresha; Webster, Stephen; Kerley, Remy; Buist, Susan; McCort-Tipton, Melanie

2012-03-15

We report for the first time an ultra performance liquid chromatographic method with tandem mass spectrometric detection (UPLC/MS/MS) for the determination of norethindrone alone in human plasma over the concentration range of 50.0-25000 pg mL(-1) using a sample volume of 0.250 mL. Norethindrone and its internal standard (ISTD), norethindrone-(13)C(2), were extracted from human plasma by supported liquid extraction (SLE). After evaporation of the organic solvent, samples were reconstituted and analyzed on an UPLC/MS/MS system. The UPLC system used a Waters BEH C18 (100 mm × 2.1mm, 1.7 μm) column with mobile phase A of 0.05% formic acid in water:acetonitrile (65:35, v/v) and mobile phase B of 0.05% formic acid in methanol:acetonitrile (50:50, v/v). The flow rate was 0.500 mL min(-1). The method was fully validated. The inter-run accuracy and precision at the lower limit of quantitation (LLOQ), low, mid and high quality control (QC) concentration levels were 99.2-108.4% with a <8.1% CV (coefficient of variation), respectively. The validated method has been successfully applied to analysis of thousands of pharmacokinetic samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Plasma capric acid concentrations in healthy subjects determined by high-performance liquid chromatography.

PubMed

Shrestha, Rojeet; Hui, Shu-Ping; Imai, Hiromitsu; Hashimoto, Satoru; Uemura, Naoto; Takeda, Seiji; Fuda, Hirotoshi; Suzuki, Akira; Yamaguchi, Satoshi; Hirano, Ken-Ichi; Chiba, Hitoshi

2015-09-01

Capric acid (FA10:0, decanoic acid) is a medium-chain fatty acid abundant in tropical oils such as coconut oil, whereas small amounts are present in milk of goat, cow, and human. Orally ingested FA10:0 is transported to the liver and quickly burnt within it. Only few reports are available for FA10:0 concentrations in human plasma. Fasting (n = 5, male/female = 3/2, age 31 ± 9.3 years old) and non-fasting (n = 106, male/female = 44/62, age 21.9 ± 3.2 years old) blood samples were collected from apparently healthy Japanese volunteers. The total FA10:0 in the plasma were measured by high-performance liquid chromatography after derivatization with 2-nitrophenylhydrazine followed by UV detection. Inter and intra-assay coefficient of variation of FA10:0 assay at three different concentrations ranged in 1.7-3.9 and 1.3-5.4%, respectively, with an analytical recovery of 95.2-104.0%. FA10:0 concentration was below detection limit (0.1 µmol/L) in each fasting human plasma. FA10:0 was not detected in 50 (47.2%) of 106 non-fasting blood samples, while 29 (27.4%) plasma samples contained FA10:0 less than or equal to 0.5 µmol/L (0.4 ± 0.1), and 27 (25.5%) contained it at more than 0.5 µmol/L (0.9 ± 0.3). A half of the non-fasting plasma samples contained detectable FA10:0. This simple, precise, and accurate high-performance liquid chromatography method might be useful for monitoring plasma FA10:0 during medium-chain triglycerides therapy. © The Author(s) 2015.

Feasibility of a responsive, hybrid propulsion augmented, Vertical-Takeoff-and-Landing, Single-Stage-to-Orbit launch system

NASA Astrophysics Data System (ADS)

Pelaccio, Dennis G.

1996-03-01

A novel, reusable, Vertical-Takeoff-and-Landing, Single-Stage-to-Orbit (VTOL/SSTO) launch system concept, named HYP-SSTO, is presented in this paper. This launch vehicle system concept uses a highly coupled, main high performance liquid oxygen/liquid hydrogen (LOX/LH2) propulsion system, that is used only for launch, with a hybrid auxiliary propulsion system which is used during final orbit insertion, major orbit maneuvering, and landing propulsive burn phases of flight. By using a hybrid propulsion system for major orbit maneuver burns and landing, this launch system concept has many advantages over conventional VTOL/SSTO concepts that use LOX/LH2 propulsion system(s) burns for all phases of flight. Because hybrid propulsion systems are relatively simple and inert by their nature, this concept has the potential to support short turnaround times between launches, be economical to develop, and be competitive in terms of overall system life-cycle cost. This paper provides a technical description of the novel, reusable HYP-SSTO launch system concept. Launch capability performance, as well as major design and operational system attributes, are identified and discussed.

[Simultaneous determination of 9 ultraviolet stabilizers in food plastic packaging materials by solid phase extraction-high performance liquid chromatography].

PubMed

Zhang, Juzhou; Li, Jing; Shao, Dongliang; Yao, Bangben; Jiang, Junshu

2012-02-01

An effective high performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of 9 ultraviolet stabilizers in food plastic packaging materials. The food packaging samples were firstly extracted by methanol-ethyl acetate, and then purified by a C18 solid-phase extraction (SPE) column. The target compounds were separated on a ZORBAX SB-C18 column (250 mm x 4.6 mm, 5 microm) in gradient elution mode using methanol and water as mobile phases. The detection wavelength was at 310 nm. The linear plots of the nine ultraviolet stabilizers were obtained between 0.2 and 10 mg/L, with the correlation coefficients of above 0. 999 for the nine ultraviolet stabilizers. The limits of detection for this method were in the range from 0.05 to 0.1 mg/L. The recoveries spiked in commercial food plastic packaging materials were in the range of 70.2% - 89.0% with the relative standard deviations of 0.4% - 4.5%. The results indicated that the method is simple, accurate, and suitable for the simultaneous determination of the nine ultraviolet stabilizers in food plastic packaging materials.

[[Chiral separation of five arylpropionic acid drugs and determination of their enantiomers in pharmaceutical preparations by reversed-phase high performance liquid chromatography with cellulose-tris-(4-methylbenzoate) stationary phase

PubMed

Luo, An; Wan, Qiang; Fan, Huajun; Chen, Zhi; Wu, Xuehao; Huang, Xiaowen; Zang, Linquan

2014-09-01

Chromatographic behaviors for enantiomeric separation of arylpropionic acid drugs were systematically developed by reversed phase-high performance liquid chromatography (RP-HPLC) using cellulose-tris-(4-methylbenzoate) (CTMB) as chiral stationary phase (CSP). The effects of the composition of the mobile phase, additives and temperature on chiral separation of flurbiprofen, pranoprofen, naproxen, ibuprofen and loxoprofen were further investigated. The enantiomers had been successfully separated on CSP of CTMB by the mobile phase of methanol-0.1% (v/v) formic acid except naproxen by acetonitrile-0.1% (v/v) formic acid at 25 °C. The mechanisms of the racemic resolution for the above mentioned five drugs are discussed thermodynamically and structurally. The resolutions between respective enantiomers for arylpropionic acid drugs on CTMB had significant differences due to their chromatographic behaviors. The order of resolutions ranked pranoprofen, loxoprofen, flurbiprofen, ibuprofen and naproxen. The method established has been successfully applied to the determination of the enantiomers of the five drugs in commercial preparations under the optimized conditions. It proved that the method is simple, reliable and accurate.

Molecularly imprinted solid-phase extraction for determination of tilmicosin in feed using high performance liquid chromatography.

PubMed

Zheng, Yaqiu; Liu, Yahong; Guo, Hongbin; He, Limin; Fang, Binghu; Zeng, Zhenling

2011-04-01

A simple, sensitive and reproducible molecularly imprinted solid-phase extraction (MISPE) coupled with high performance liquid chromatographic method was developed for monitoring tilmicosin in feeds. The polymers were prepared using tylosin as mimic template molecule, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linking monomer, and chloroform as a solvent by bulk polymerization. Under the optimum MISPE conditions, the novel polymer sorbent can selectively extract and enrich tilmicosin from variety of feeds. The MISPE cartridge was better than non-imprinted, C(18) and HLB cartridges in terms of both recovery and precision. Mean recoveries of tilmicosin from five kinds of feeds spiked at 1, 10 and 50 mg kg(-1) ranged from 76.9% to 95.6%, with intra-day and inter-day relative standard deviation less than 7.6%. The linearity was ranged from 1.0 to 100 mg L(-1) for matrix standard solution (r=0.9990). The limit of detection was approximately 0.35 mg kg(-1) and the limit of quantification was approximately 0.98 mg kg(-1). There was cleaner chromatogram by using MISPE than C(18) and HLB SPE. Copyright © 2011 Elsevier B.V. All rights reserved.

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

Residue analysis and persistence evaluation of fipronil and its metabolites in cotton using high-performance liquid chromatography-tandem mass spectrometry.

PubMed

Wu, Xiaohu; Yu, Yang; Xu, Jun; Dong, Fengshou; Liu, Xingang; Du, Pengqiang; Wei, Dongmei; Zheng, Yongquan

2017-01-01

A simple residue analytical method based on the QuEChERS approach and high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection was developed for the analysis of fipronil and its three metabolites in cottonseed, cotton plant and soil. The average recoveries of four test compounds from all three matrices were 78.6-108.9% at the level of 0.005 to 0.5 mg/kg, with an RSD in the range of 0.6 to 13.7%. The limit of quantification (LOQ) of the four test compounds ranged from 0.005 to 0.01 mg/kg. The results of the residual dynamics experiments showed that fipronil dissipated rapidly in cotton plants and soil and that oxidation and photolysis were the main degradation pathways. Moreover, the bi-exponential models demonstrated a good fit of the measured data for fipronil in cotton plants and soil, with R2 in the range of 0.8989 to 0.9989. Furthermore, a total of 40 samples of cottonseed from Shandong Province were analyzed, and all of the samples were free from the four test compound residues.

Residue analysis and persistence evaluation of fipronil and its metabolites in cotton using high-performance liquid chromatography-tandem mass spectrometry

PubMed Central

Wu, Xiaohu; Yu, Yang; Xu, Jun; Dong, Fengshou; Liu, Xingang; Du, Pengqiang; Wei, Dongmei; Zheng, Yongquan

2017-01-01

A simple residue analytical method based on the QuEChERS approach and high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection was developed for the analysis of fipronil and its three metabolites in cottonseed, cotton plant and soil. The average recoveries of four test compounds from all three matrices were 78.6–108.9% at the level of 0.005 to 0.5 mg/kg, with an RSD in the range of 0.6 to 13.7%. The limit of quantification (LOQ) of the four test compounds ranged from 0.005 to 0.01 mg/kg. The results of the residual dynamics experiments showed that fipronil dissipated rapidly in cotton plants and soil and that oxidation and photolysis were the main degradation pathways. Moreover, the bi-exponential models demonstrated a good fit of the measured data for fipronil in cotton plants and soil, with R2 in the range of 0.8989 to 0.9989. Furthermore, a total of 40 samples of cottonseed from Shandong Province were analyzed, and all of the samples were free from the four test compound residues. PMID:28291815

Rapid and sensitive quantitation of the antiproliferative agent mitoguazone in small volumes of plasma by high-performance liquid chromatography with ultraviolet detection.

PubMed

Cheng, Ching-Ling; Lin, E Gin; Chou, Chen-Hsi

2003-08-15

Mitoguazone is an antiproliferative agent used in chemotherapy. This study describes a simple and sensitive high-performance liquid chromatographic method for the determination of mitoguazone in 100 microl of plasma. Samples were deproteinized with 100 microl of a solution of internal standard (amiloride, 10 microg/ml) in acetonitrile. An aliquot of the supernatant was injected onto the column. HPLC separation was achieved on a silica column with the mobile phase of methanol-50 mM potassium phosphate buffer (pH 3)-triethylamine (80:20:0.3, v/v), at a flow-rate of 1 ml/min. The eluent was detected at 320 nm. The retention time was about 5.5 min for amiloride and 12 min for mitoguazone. No endogenous substances were found to interfere. Calibration curves were linear from 0.25 to 50 microg/ml. The absolute recoveries of mitoguazone and amiloride were both greater than 84%. The limit of quantitation was 0.25 microg/ml. The intra- and inter-day precision (expressed as RSD) was 5.8%, or less, and the accuracy was 94.7% of the nominal concentration. The method is suitable in pharmacokinetic investigation and monitoring mitoguazone concentration.

Determination of N-glycans by high performance liquid chromatography using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate as the glycosylamine labeling reagent.

PubMed

Wu, Yike; Sha, Qiuyue; Du, Juan; Wang, Chang; Zhang, Liang; Liu, Bi-Feng; Lin, Yawei; Liu, Xin

2018-02-02

Robust, efficient identification and accurate quantification of N-glycans are of great significance in N-glycomics analysis. Here, a simple and rapid derivatization method, based on the combination of microwave-assisted deglycosylation and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) labeling, was developed for the analysis of N-glycan by high performance liquid chromatography with fluorescence detection (HPLC-FLD). After optimizing various parameters affecting deglycosylation and derivatization by RNase B, the time for N-glycan labeling was shortened to 50 min with ∼10-fold enhancement in detection sensitivity comparing to conventional 2-aminobenzoic acid (2-AA) labeling method. Additionally, the method showed good linearity (correlation coefficients > 0.991) and reproducibility (RSD < 8.7%). These advantages of the proposed method were further validated by the analysis of complex samples, including fetuin and human serum. Investigation of serum N-glycome for preliminary diagnosis of human lung cancer was conducted, where significant changes of several N-glycans corresponding to core-fucosylated, mono- and disialylated glycans have been evidenced by a series of statistical analysis. Copyright © 2018 Elsevier B.V. All rights reserved.

[Direct determination of purine bases in tea by reversed-phase high performance liquid chromatography].

PubMed

Ding, M; Yang, H; Xiao, S; Chen, P

1999-09-01

A reversed-phase high performance liquid chromatographic(RP-HPLC) method for the direct determination of three purine bases(theobromin, theophyllin and caffeine) in tea was developed. An ODS column with Zorbax SB-C18(4.6 mm i.d. x 250 mm, 5 microns) was employed. The aqueous solution of methanol containing 0.05% of acetic acid and 0.25% of N,N-dimethylformamide(DMF) was used as eluent with a flow rate of 0.8 mL/min. In this method, the aqueous extract of tea can be injected into HPLC directly, but in current HPLC methods for purine bases the coexisted tea polyphenols must be pre-separated. The three purine bases in tea were separated without any interference from the coexisted tea polyphenols. This method is simple (without any special sample pretreatment) and sensitive with detection limits (S/N = 3) of 0.7, 0.9 and 1.8 mg/L for theobromin, theophyllin and caffeine respectively. The linear range of the calibration curve of peak area for the three purine bases were from 6 mg/L to 1,000 mg/L with a correlation coefficient (r) of 0.998-0.999.

A practical and highly sensitive C3N4-TYR fluorescent probe for convenient detection of dopamine

NASA Astrophysics Data System (ADS)

Li, Hao; Yang, Manman; Liu, Juan; Zhang, Yalin; Yang, Yanmei; Huang, Hui; Liu, Yang; Kang, Zhenhui

2015-07-01

The C3N4-tyrosinase (TYR) hybrid is a highly accurate, sensitive and simple fluorescent probe for the detection of dopamine (DOPA). Under optimized conditions, the relative fluorescence intensity of C3N4-TYR is proportional to the DOPA concentration in the range from 1 × 10-3 to 3 × 10-8 mol L-1 with a correlation coefficient of 0.995. In the present system, the detection limit achieved is as low as 3 × 10-8 mol L-1. Notably, these quantitative detection results for clinical samples are comparable to those of high performance liquid chromatography. Moreover, the enzyme-encapsulated C3N4 sensing arrays on both glass slide and test paper were evaluated, which revealed sensitive detection and excellent stability. The results reported here provide a new approach for the design of a multifunctional nanosensor for the detection of bio-molecules.The C3N4-tyrosinase (TYR) hybrid is a highly accurate, sensitive and simple fluorescent probe for the detection of dopamine (DOPA). Under optimized conditions, the relative fluorescence intensity of C3N4-TYR is proportional to the DOPA concentration in the range from 1 × 10-3 to 3 × 10-8 mol L-1 with a correlation coefficient of 0.995. In the present system, the detection limit achieved is as low as 3 × 10-8 mol L-1. Notably, these quantitative detection results for clinical samples are comparable to those of high performance liquid chromatography. Moreover, the enzyme-encapsulated C3N4 sensing arrays on both glass slide and test paper were evaluated, which revealed sensitive detection and excellent stability. The results reported here provide a new approach for the design of a multifunctional nanosensor for the detection of bio-molecules. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr03316k

Sensitive determination of nitrophenol isomers by reverse-phase high-performance liquid chromatography in conjunction with liquid-liquid extraction

USDA-ARS?s Scientific Manuscript database

A method for the highly sensitive determination of 2-, 3- and 4- nitrophenols was developed using reverse-phase high-performance liquid chromatography (RP-HPLC) with a UV photodiode array detector. Using a reverse-phase column and 40% aqueous acetonitrile as an eluent (i.e. isocratic elution), the i...

Determination of rivaroxaban in patient’s plasma samples by anti-Xa chromogenic test associated to High Performance Liquid Chromatography tandem Mass Spectrometry (HPLC-MS/MS)

PubMed Central

Derogis, Priscilla Bento Matos; Sanches, Livia Rentas; de Aranda, Valdir Fernandes; Colombini, Marjorie Paris; Mangueira, Cristóvão Luis Pitangueira; Katz, Marcelo; Faulhaber, Adriana Caschera Leme; Mendes, Claudio Ernesto Albers; Ferreira, Carlos Eduardo dos Santos; França, Carolina Nunes; Guerra, João Carlos de Campos

2017-01-01

Rivaroxaban is an oral direct factor Xa inhibitor, therapeutically indicated in the treatment of thromboembolic diseases. As other new oral anticoagulants, routine monitoring of rivaroxaban is not necessary, but important in some clinical circumstances. In our study a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was validated to measure rivaroxaban plasmatic concentration. Our method used a simple sample preparation, protein precipitation, and a fast chromatographic run. It was developed a precise and accurate method, with a linear range from 2 to 500 ng/mL, and a lower limit of quantification of 4 pg on column. The new method was compared to a reference method (anti-factor Xa activity) and both presented a good correlation (r = 0.98, p < 0.001). In addition, we validated hemolytic, icteric or lipemic plasma samples for rivaroxaban measurement by HPLC-MS/MS without interferences. The chromogenic and HPLC-MS/MS methods were highly correlated and should be used as clinical tools for drug monitoring. The method was applied successfully in a group of 49 real-life patients, which allowed an accurate determination of rivaroxaban in peak and trough levels. PMID:28170419

Spectrophotometric and high performance liquid chromatographic methods for sensitive determination of bisphenol A

NASA Astrophysics Data System (ADS)

Zhuang, Yafeng; Zhou, Meng; Gu, Jia; Li, Xiangmei

2014-03-01

A new spectrophotometric method for the determination of trace amounts of bisphenol A based on a diazotization-coupling reaction was developed. In acidic solution, clenbuterol was first diazotized with sodium nitrite, then coupled with bisphenol A to from an azo-compound [I] in NH3-NH4Cl buffer, which shows a maximum absorption at 410 nm. The effects of the amount of sodium nitrite, diazo reaction time, the amount of clenbuterol, coupling reaction time and coupling reaction temperature have been examined. Under the optional conditions, the determination of the linear range of bisphenol A is 0.24-8.4 μg/mL, correlation coefficient is 0.9905 and detection limit of this method is 0.15 μg/mL. The spectrophotometric method is simple, rapid, high sensitivity with better accuracy. High performance liquid chromatography (HPLC) technique combined with this new spectrophotometric method has been also developed for the measurement of bisphenol A. The analysis was achieved on a C18 column using water and methanol as a mobile phase and the detection was done spectrophotometrically at 410 nm. These reported methods were applied to the determination of bisphenol A in hot water in contact with commercially available table-water bottle samples.

High Performance Fatty Acid-Based Vinyl Ester Resin for Liquid Molding

DTIC Science & Technology

2007-07-01

High Performance Fatty Acid -Based Vinyl Ester Resin for Liquid Molding by Xing Geng, John J. La Scala, James M. Sands, and Giuseppe R...it to the originator. Army Research Laboratory Aberdeen Proving Ground, MD 21005-5069 ARL-RP-184 July 2007 High Performance Fatty Acid ...CONTRACT NUMBER 5b. GRANT NUMBER 4. TITLE AND SUBTITLE High Performance Fatty Acid -Based Vinyl Ester Resin for Liquid Molding 5c. PROGRAM

Development of high-throughput multi-residue method for non-steroidal anti-inflammatory drugs monitoring in swine muscle by LC-MS/MS.

PubMed

Castilhos, Tamara S; Barreto, Fabiano; Meneghini, Leonardo; Bergold, Ana Maria

2016-07-01

A reliable and simple method for the detection and quantification of residues of 14 non-steroidal anti-inflammatory drugs and a metamizole metabolite in swine muscle was developed using liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS). The samples were extracted with acetonitrile (ACN) in solid-liquid extraction followed by a low-temperature partitioning (LLE-LTP) process at -20 ± 2°C. After evaporation to dryness, the residue was reconstituted with hexane and a mixture of water:acetonitrile (1:1). LC separation was achieved on a reversed-phase (RP18) column with gradient elution using water (phase A) and ACN (phase B) both containing 1 mmol l(-)(1) ammonium acetate (NH4COO) with 0.025% acetic acid. Analysis was carried out on a triple-quadrupole tandem mass spectrometer (LC-MS/MS) in multiple reaction monitoring mode using an electrospray interface in negative and positive mode in a single run. Method validation was performed according to the criteria of Commission Decision No. 2002/657/EC. The matrix effect and linearity were evaluated. Decision limit (CCα), detection capability (CCβ), accuracy and repeatability of the method are also reported. The proposed method proved to be simple, easy and adequate for high-throughput analysis and was applied to routine analysis by the Brazilian Ministry of Agriculture, Livestock and Food Supply.

Using dispersive liquid-liquid microextraction and liquid chromatography for determination of guaifenesin enantiomers in human urine.

PubMed

Hatami, Mehdi; Farhadi, Khalil; Abdollahpour, Assem

2011-11-01

A simple, rapid, and efficient method, dispersive liquid-liquid microextraction (DLLME) coupled with high-performance liquid chromatography-fluorescence detector, has been developed for the determination of guaifenesin (GUA) enantiomers in human urine samples after an oral dose administration of its syrup formulation. Urine samples were collected during the time intervals 0-2, 2-4, and 4-6 h and concentration and ratio of two enantiomers was determined. The ratio of R-(-) to S-(+) enantiomer concentrations in urine showed an increase with time, with R/S ratios of 0.66 at 2 h and 2.23 at 6 h. For microextraction process, a mixture of extraction solvent (dichloromethane, 100 μL) and dispersive solvent (THF, 1 mL) was rapidly injected into 5.0 mL diluted urine sample for the formation of cloudy solution and extraction of enantiomers into the fine droplets of CH(2)Cl(2). After optimization of HPLC enantioselective conditions, some important parameters, such as the kind and volume of extraction and dispersive solvents, extraction time, temperature, pH, and salt effect were optimized for dispersive liquid-liquid microextraction process. Under the optimum extraction condition, the method yields a linear calibration curve in the concentration range from 10 to 2000 ng/mL for target analytes. LOD was 3.00 ng/mL for both of the enantiomers. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Very Stable High Throughput Taylor Cone-jet in Electrohydrodynamics

PubMed Central

Morad, M. R.; Rajabi, A.; Razavi, M.; Sereshkeh, S. R. Pejman

2016-01-01

A stable capillary liquid jet formed by an electric field is an important physical phenomenon for formation of controllable small droplets, power generation and chemical reactions, printing and patterning, and chemical-biological investigations. In electrohydrodynamics, the well-known Taylor cone-jet has a stability margin within a certain range of the liquid flow rate (Q) and the applied voltage (V). Here, we introduce a simple mechanism to greatly extend the Taylor cone-jet stability margin and produce a very high throughput. For an ethanol cone-jet emitting from a simple nozzle, the stability margin is obtained within 1 kV for low flow rates, decaying with flow rate up to 2 ml/h. By installing a hemispherical cap above the nozzle, we demonstrate that the stability margin could increase to 5 kV for low flow rates, decaying to zero for a maximum flow rate of 65 ml/h. The governing borders of stability margins are discussed and obtained for three other liquids: methanol, 1-propanol and 1-butanol. For a gravity-directed nozzle, the produced cone-jet is more stable against perturbations and the axis of the spray remains in the same direction through the whole stability margin, unlike the cone-jet of conventional simple nozzles. PMID:27917956

Species discrimination of Radix Bupleuri through the simultaneous determination of ten saikosaponins by high performance liquid chromatography with evaporative light scattering detection and electrospray ionization mass spectrometry.

PubMed

Lee, Jaehyun; Yang, Dong-Hyug; Suh, Joon Hyuk; Kim, Unyong; Eom, Han Young; Kim, Junghyun; Lee, Mi Young; Kim, Jinwoong; Han, Sang Beom

2011-12-15

A simple, rapid and robust high performance liquid chromatography-evaporative light scattering detection (HPLC-ELSD) method was established for the species discrimination and quality evaluation of Radix Bupleuri through the simultaneous determination of ten saikosaponins, namely saikosaponin-a, -b(1), -b(2), -b(3), -b(4), -c, -d, -g, -h, and -i. These compounds were chromatographed on an Ascentis(®) Express C18 column with a gradient elution of acetonitrile and water containing 0.1% acetic acid at a flow rate of 1.0 mL/min. Saikosaponins were monitored by ELSD, which was operated at a 50°C drift tube temperature and 3.0 bar nebulizer gas (N(2)) pressure. The developed method was validated with respect to linearity, intra- and inter-day accuracy and precision, limit of quantification (LOQ), recovery, robustness and stability, thereby showing good precision and accuracy, with intra- and inter-assay coefficients of variation less than 15% at all concentrations. Furthermore, a high performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) method was developed to certify the existence of ten saikosaponins, as well as to confirm the reliability of ELSD. The extraction conditions of saikosaponins from Radix Bupleuri were also optimized by investigating the effect of extraction methods (sonication, reflux and maceration) and various solvents on the extraction efficiencies for saikosaponins. Sonication with 70% methanol for 40 min was found to be simple and effective for extraction of major saikosaponins. This analytical method was applied to determine saikosaponin profiles in 20 real samples consisting of four Bupleurum species, namely B. falcatum, B. chinense, B. sibiricum and the poisonous B. longiradiatum. It was found that three major saikosaponin-a, -c and -d were the major constituents in B. falcatum, B. chinense, and B. longiradiatum, while one major saikosaponin (saikosaponin-c) was not identified from B. sibiricum. In addition, no saikosaponin-b(3) was detected in B. longiradiatum samples, indicating that the toxic B. longiradiatum may be tentatively distinguished from officially listed Bupleurum species (B. falcatum and B. chinense) based on their saikosaponin profiles. Overall the simultaneous determination of ten saikosaponins in Radix Bupleuri was shown to be a promising tool to adopt for the discrimination and quality control of closely related Bupleurum species. Copyright © 2011 Elsevier B.V. All rights reserved.

Non-enzymatic synthesis of the coenzymes, uridine diphosphate glucose and cytidine diphosphate choline, and other phosphorylated metabolic intermediates

NASA Technical Reports Server (NTRS)

Mar, A.; Dworkin, J.; Oro, J.

1987-01-01

Using urea and cyanamide, the two condensing agents considered to have been present on the primitive earth, uridine diphosphate glucose (UDPG), cytidine diphosphate choline (CDP-choline), glucose-1-phosphate (G1P), and glucose-6-phosphate (G6P) were synthesized under simulated prebiotic conditions. The reaction products were separated and identified using paper chromatography, thin layer chromatography, enzymatic analyses, and ion-pair reverse-phase high performance liquid chromatography. The possibility of nonenzymatic synthesis of metabolic intermediates on the primitive earth from simple precursors was thus demonstrated.

Comparison between micellar liquid chromatography and capillary zone electrophoresis for the determination of hydrophobic basic drugs in pharmaceutical preparations.

PubMed

Torres-Cartas, S; Martín-Biosca, Y; Sagrado, S; Villanueva-Camañas, R M; Medina-Hernández, M J

2007-01-01

The determination of highly hydrophobic basic compounds by means of conventional reversed-phase liquid chromatographic methods has several drawbacks. Owing to the characteristics of micellar liquid chromatography (MLC) and capillary electrophoresis (CE), these techniques could be advantageous alternatives to reversed-phase chromatographic methods for the determination of these kinds of compounds. The objective of this study was to develop and compare MLC and CE methods for the determination of antipsychotic basic drugs (amitryptiline, haloperidol, perphenazine and thioridazine) in pharmaceutical preparations. The chromatographic determination of the analytes was performed on a Kromasil C(18) analytical column; the mobile phase was 0.04 m cetyltrimethylammonium bromide (CTAB), at pH 3, containing 5% 1-butanol, at a flow rate of 1 mL/min. The CE separation was performed in a fused-silica capillary with a 50 mm tris-(hydroxymethyl)-aminomethane buffer, pH 7, at an applied voltage of 20 kV, using barbital as internal stardard. The proposed methods are suitable for a reliable quantitation of these compounds in the commercial tablets and drops in terms of accuracy and precision and require a very simple pre-treatment of the samples. By comparing the performance characteristics and experimental details of the MLC and CE methods we conclude that CE seems to be slightly better than MLC in the determination of highly hydrophobic compounds in pharmaceuticals in terms of resolution and economy, taking into account that the limits of detection are not a handicap in pharmaceutical samples. Copyright 2006 John Wiley & Sons, Ltd.

A novel liquid chromatography method using diode-array detector for the determination of oleuropein in dietary supplements.

PubMed

Bertolini, Tiziana; Vicentini, Lorenza; Boschetti, Silvia; Andreatta, Paolo; Gatti, Rita

2016-09-10

A simple and fast chromatographic method using ultraviolet diode-array detector (UV-DAD) was developed for the automatic high performance liquid chromatography (HPLC) determination of the title of oleuropein in a new dietary supplements in form of effervescent granules. The chromatographic separations were performed on a C18 core-shell column with detection at λ=232nm. The mobile phase consisted of deionized water with 0.1% TFA and acetonitrile under gradient conditions at a flow-rate of 0.8mL/min. Oleuropein and oleuroside present in the raw material were characterized by high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The validation of the analytical procedure has been performed determining the following parameters: specificity, linearity, repeatability, reproducibility, accuracy, limit of quantification (LOQ), stability of the standard and sample solutions. Linear response was observed in fortified placebo solutions (determination coefficient: 0.9998). Intra-day precision (relative standard deviation, RSD) was ≤5.0% for peak area and for retention times (tR) without significant differences between intra- and inter-day data. The limits of quantitation (LOQ) was about 5μg/mL and 9pmol/inject. Oleuropein recovery studies gave good results (99.9%) with a R.S.D. of 0.5%. The speed of analysis and the stability of the solutions with a fluctuation Δ (%) ≤2.0 at room temperature means an undoubted advantage of the method allowing the simultaneous preparation of many samples and consecutive chromatographic analyses by using an autosampler. The developed method is suitable for the quality control of oleuropein in raw material and industrial products. The method can be applied in any analytical laboratory not requiring a sophisticated instrumentation. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of hydroxylated polycyclic aromatic hydrocarbons by HPLC-photoionization tandem mass spectrometry in wood smoke particles and soil samples.

PubMed

Avagyan, Rozanna; Nyström, Robin; Boman, Christoffer; Westerholm, Roger

2015-06-01

A simple and fast method for analysis of hydroxylated polycyclic aromatic hydrocarbons using pressurized liquid extraction and high performance liquid chromatography utilizing photoionization tandem mass spectrometry was developed. Simultaneous separation and determination of nine hydroxylated polycyclic aromatic hydrocarbons and two hydroxy biphenyls could be performed in negative mode with a run time of 12 min, including equilibration in 5 min. The calibration curves were in two concentration ranges; 1-50 ng/mL and 0.01-50 μg/mL, with coefficients of correlation R (2) > 0.997. The limits of detection and method quantification limits were in the range of 9-56 pg and 5-38 ng/g, respectively. A two-level full factorial experimental design was used for screening of conditions with the highest impact on the extraction. The extraction procedure was automated and suitable for a large number of samples. The extraction recoveries ranged from 70 to 102 % and the matrix effects were between 92 and 104 %. The overall method was demonstrated on wood smoke particles and soil samples with good analytical performance, and five OH-PAHs were determined in the concentration range of 0.19-210 μg/g. As far as we know, hydroxylated polycyclic aromatic hydrocarbons were determined in wood smoke and soil samples using photoionization mass spectrometry for the first time in this present study. Accordingly, this study shows that high performance liquid chromatography photoionization tandem mass spectrometry can be a good option for the determination of hydroxylated polycyclic aromatic hydrocarbons in complex environmental samples. Graphical Abstract The method developed in this study was used to determine hydroxylated polycyclic aromatic hydrocarbons in wood smoke and soil.

Integration of phase separation with ultrasound-assisted salt-induced liquid-liquid microextraction for analyzing the fluoroquinones in human body fluids by liquid chromatography.

PubMed

Wang, Huili; Gao, Ming; Wang, Mei; Zhang, Rongbo; Wang, Wenwei; Dahlgren, Randy A; Wang, Xuedong

2015-03-15

Herein, we developed a novel integrated device to perform phase separation based on ultrasound-assisted salt-induced liquid-liquid microextraction for determination of five fluoroquinones (FQs) in human body fluids. The integrated device consisted of three simple HDPE components used to separate the extraction solvent from the aqueous phase prior to retrieving the extractant. A series of extraction parameters were optimized using the response surface method based on central composite design. Optimal conditions consisted of 945μL acetone extraction solvent, pH 2.1, 4.1min stir time, 5.9g Na2SO4, and 4.0min centrifugation. Under optimized conditions, the limits of detection (at S/N=3) were 0.12-0.66μgL(-1), the linear range was 0.5-500μgL(-1) and recoveries were 92.6-110.9% for the five FQs extracted from plasma and urine. The proposed method has several advantages, such as easy construction from inexpensive materials, high extraction efficiency, short extraction time, and compatibility with HPLC analysis. Thus, this method shows excellent prospects for sample pretreatment and analysis of FQs in human body fluids. Copyright © 2015 Elsevier B.V. All rights reserved.

Gold metal liquid-like droplets.

PubMed

Smirnov, Evgeny; Scanlon, Micheál D; Momotenko, Dmitry; Vrubel, Heron; Méndez, Manuel A; Brevet, Pierre-Francois; Girault, Hubert H

2014-09-23

Simple methods to self-assemble coatings and films encompassing nanoparticles are highly desirable in many practical scenarios, yet scarcely any examples of simple, robust approaches to coat macroscopic droplets with continuous, thick (multilayer), reflective and stable liquid nanoparticle films exist. Here, we introduce a facile and rapid one-step route to form films of reflective liquid-like gold that encase macroscopic droplets, and we denote these as gold metal liquid-like droplets (MeLLDs). The present approach takes advantage of the inherent self-assembly of gold nanoparticles at liquid-liquid interfaces and the increase in rates of nanoparticle aggregate trapping at the interface during emulsification. The ease of displacement of the stabilizing citrate ligands by appropriate redox active molecules that act as a lubricating molecular glue is key. Specifically, the heterogeneous interaction of citrate stabilized aqueous gold nanoparticles with the lipophilic electron donor tetrathiafulvalene under emulsified conditions produces gold MeLLDs. This methodology relies exclusively on electrochemical reactions, i.e., the oxidation of tetrathiafulvalene to its radical cation by the gold nanoparticle, and electrostatic interactions between the radical cation and nanoparticles. The gold MeLLDs are reversibly deformable upon compression and decompression and kinetically stable for extended periods of time in excess of a year.

Stretchable, Twisted Conductive Microtubules for Wearable Computing, Robotics, Electronics, and Healthcare.

PubMed

Do, Thanh Nho; Visell, Yon

2017-05-11

Stretchable and flexible multifunctional electronic components, including sensors and actuators, have received increasing attention in robotics, electronics, wearable, and healthcare applications. Despite advances, it has remained challenging to design analogs of many electronic components to be highly stretchable, to be efficient to fabricate, and to provide control over electronic performance. Here, we describe highly elastic sensors and interconnects formed from thin, twisted conductive microtubules. These devices consist of twisted assemblies of thin, highly stretchable (>400%) elastomer tubules filled with liquid conductor (eutectic gallium indium, EGaIn), and fabricated using a simple roller coating process. As we demonstrate, these devices can operate as multimodal sensors for strain, rotation, contact force, or contact location. We also show that, through twisting, it is possible to control their mechanical performance and electronic sensitivity. In extensive experiments, we have evaluated the capabilities of these devices, and have prototyped an array of applications in several domains of stretchable and wearable electronics. These devices provide a novel, low cost solution for high performance stretchable electronics with broad applications in industry, healthcare, and consumer electronics, to emerging product categories of high potential economic and societal significance.

Microwave-Assisted Synthesis of Highly-Crumpled, Few-Layered Graphene and Nitrogen-Doped Graphene for Use as High-Performance Electrodes in Capacitive Deionization

NASA Astrophysics Data System (ADS)

Amiri, Ahmad; Ahmadi, Goodarz; Shanbedi, Mehdi; Savari, Maryam; Kazi, S. N.; Chew, B. T.

2015-12-01

Capacitive deionization (CDI) is a promising procedure for removing various charged ionic species from brackish water. The performance of graphene-based material in capacitive deionization is lower than the expectation of the industry, so highly-crumpled, few-layered graphene (HCG) and highly-crumpled nitrogen-doped graphene (HCNDG) with high surface area have been introduced as promising candidates for CDI electrodes. Thus, HCG and HCNDG were prepared by exfoliation of graphite in the presence of liquid-phase, microwave-assisted methods. An industrially-scalable, cost-effective, and simple approach was employed to synthesize HCG and HCNDG, resulting in few-layered graphene and nitrogen-doped graphene with large specific surface area. Then, HCG and HCNDG were utilized for manufacturing a new class of carbon nanostructure-based electrodes for use in large-scale CDI equipment. The electrosorption results indicated that both the HCG and HCNDG have fairly large specific surface areas, indicating their huge potential for capacitive deionization applications.

Optical biosensor based on liquid crystal droplets for detection of cholic acid

NASA Astrophysics Data System (ADS)

Niu, Xiaofang; Luo, Dan; Chen, Rui; Wang, Fei; Sun, Xiaowei; Dai, Haitao

2016-12-01

A highly sensitive cholic acid biosensor based on 4-cyano-4‧-penthlbiphenyl (5CB) Liquid crystal droplets in phosphate buffer saline solution was reported. A radial-to-bipolar transition of 5CB droplet would be triggered during competitive reaction of CA at the sodium dodecyl sulfate surfactant-laden 5CB droplet surface. Our liquid crystal droplet sensor is a low-cost, simple and fast method for CA detection. The detection limit (5 μM) of our method is 2.4 times lower than previously report by using liquid crystal film to detection of CA.

A Simple System for Observing Dynamic Phase Equilibrium via an Inquiry-Based Laboratory or Demonstration

ERIC Educational Resources Information Center

Cloonan, Carrie A.; Andrew, Julie A.; Nichol, Carolyn A.; Hutchinson, John S.

2011-01-01

This article describes an activity that can be used as an inquiry-based laboratory or demonstration for either high school or undergraduate chemistry students to provide a basis for understanding both vapor pressure and the concept of dynamic phase equilibrium. The activity includes a simple setup to create a closed system of only water liquid and…

X-Ray Scattering Studies of the Liquid-Vapor Interface of Gallium.

NASA Astrophysics Data System (ADS)

Kawamoto, Eric Hitoshi

A UHV system was developed for performing X-ray scattering studies and in situ analyses of liquid metal surfaces. A nearly ideal choice for this study, gallium has a melting point just above room temperature; is amenable to handling in both air and vacuum; its surface oxides can be removed while its cleanliness is maintained and monitored. Using argon glow-discharge sputtering techniques to remove intervening surface oxides, thin wetting layers of gallium were prepared atop nonreactive substrates, to be used as samples suited for liquid surface scattering experiments. Preliminary measurements of X-ray reflectivity from the liquid-vapor interface of gallium were performed with the X-ray UHV chamber configured for use in conjunction with liquid surface spectrometers at two synchrotron beamlines. A novel technique for carrying out and interpreting scattering measurements from curved liquid surfaces was demonstrated. The energy tunability and intense focused white beam flux from a wiggler source was shown to place within reach the large values of wavevector transfer at which specular reflectivity data yield small length scale information about surface structure. Various theoretical treatments and simulations predict quasi-lamellar ordering of atoms near the free surface of metallic liquids due to energetics particular to metals (electron delocalization, the dependence of system energy on ion and electron densities, surface tension and electrostatic energy). However, the experimental data reported to date is insufficient to distinguish between a monotonic, sigmoidal electron density profile found at the free surfaces of dielectric liquids, and the damped oscillatory layer-like profiles anticipated for metallic liquids. Out to a wavevector transfer of Q = 0.55 A ^{-1}, the reflectivity data measured from a curved Ga surface is not inconsistent with what is expected for a liquid-vapor electron density profile of Gaussian width sigma = 1.3 +/- 0.2 A. Subsequent measurements roughly tripled the range of Q, but an oxidized surface led to poor data and hindered interpretation. The analysis presented is speculative at best, but within the context of the thermally excited capillary wave model of simple liquid surfaces, there seems to be no serious deviation from the simple Gaussian interfacial profile with the aforementioned roughness.

[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.

A novel HPLC-MS/MS method for the simultaneous determination of astemizole and its major metabolite in dog or monkey plasma and application to pharmacokinetics.

PubMed

Back, Hyun-moon; Lee, Jong-Hwa; Chae, Jung-woo; Song, Byungjeong; Seo, Joung-Wook; Yun, Hwi-yeol; Kwon, Kwang-il

2015-10-10

Astemizole (AST), a second-generation antihistamine, is metabolized to desmethyl astemizole (DEA), and although it has been removed from the market for inducing QT interval prolongation, it has reemerged as a potential anticancer and antimalarial agent. This report describes a novel high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for simultaneously determining the concentrations of AST and DEA in beagle dog and cynomolgus monkey plasma with simple preparation method and short retention time. Prior to HPLC analyses, the plasma samples were extracted with simple liquid-liquid extraction method. The isocratic mobile phase was 0.025% trifluoroacetic acid (TFA dissolved in acetonitrile) and 20 mM ammonium acetate (94:6) at a flow rate of 0.25 mL/min and diphenhydramine used as internal standard. In MS/MS analyses, precursor ions of the analytes were optimized as protonated molecular ions: [M+H](+). The lower limit of quantification of astemizole was 2.5 ng/mL in both species and desmethyl astemizole were 7.5 ng/mL and 10 ng/mL in dog and monkey plasma, respectively. The accuracy, precision, and stability of the method were in accordance with FDA guidelines for the validation of bioanalytical methods. Finally this validated method was successfully applied to a pharmacokinetic study in dogs and monkeys after oral administration of 10 mg/kg AST. Copyright © 2015 Elsevier B.V. All rights reserved.

The influence of cavitation on the flow characteristics of liquid nitrogen through spray nozzles: A CFD study

NASA Astrophysics Data System (ADS)

Xue, Rong; Ruan, Yixiao; Liu, Xiufang; Cao, Feng; Hou, Yu

2017-09-01

Spray cooling with cryogen could achieve lower temperature level than refrigerant spray. The internal flow conditions within spray nozzles have crucial impacts on the mass flow rate, particle size, spray angle and spray penetration, thereby influencing the cooling performance. In this paper, CFD simulations based on mixture model are performed to study the cavitating flow of liquid nitrogen in spray nozzles. The cavitation model is verified using the experimental results of liquid nitrogen flow over hydrofoil. The numerical models of spray nozzle are validated against the experimental data of the mass flow rate of liquid nitrogen flow through different types of nozzles including the pressure swirl nozzle and the simple convergent nozzle. The numerical studies are performed under a wide range of pressure difference and inflow temperature, and the vapor volume fraction distribution, outlet vapor quality, mass flow rate and discharge coefficient are obtained. The results show that the outlet diameter, the pressure difference, and the inflow temperature significantly influence the mass flow rate of spray nozzles. The increase of the inflow temperature leads to higher saturation pressure, higher cavitation intensity, and more vapor at nozzle outlet, which can significantly reduce mass flow rate. While the discharge coefficient is mainly determined by the inflow temperature and has little dependence on the pressure difference and outlet diameter. Based on the numerical results, correlations of discharge coefficient are proposed for pressure swirl nozzle and simple convergent nozzles, respectively, and the deviation is less than 20% for 93% of data.

Chromatographic behavior of small organic compounds in low-temperature high-performance liquid chromatography using liquid carbon dioxide as the mobile phase.

PubMed

Motono, Tomohiro; Nagai, Takashi; Kitagawa, Shinya; Ohtani, Hajime

2015-07-01

Low-temperature high-performance liquid chromatography, in which a loop injector, column, and detection cell were refrigerated at -35ºC, using liquid carbon dioxide as the mobile phase was developed. Small organic compounds (polyaromatic hydrocarbons, alkylbenzenes, and quinones) were separated by low-temperature high-performance liquid chromatography at temperatures from -35 to -5ºC. The combination of liquid carbon dioxide mobile phase with an octadecyl-silica (C18 ) column provided reversed phase mode separation, and a bare silica-gel column resulted in normal phase mode separation. In both the cases, nonlinear behavior at approximately -15ºC was found in the relationship between the temperature and the retention factors of the analytes (van't Hoff plots). In contrast to general trends in high-performance liquid chromatography, the decrease in temperature enhanced the separation efficiency of both the columns. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A rapid liquid chromatography determination of free formaldehyde in cod.

PubMed

Storey, Joseph M; Andersen, Wendy C; Heise, Andrea; Turnipseed, Sherri B; Lohne, Jack; Thomas, Terri; Madson, Mark

2015-01-01

A rapid method for the determination of free formaldehyde in cod is described. It uses a simple water extraction of formaldehyde which is then derivatised with 2,4-dinitrophenylhydrazine (DNPH) to form a sensitive and specific chromophore for high-performance liquid chromatography (HPLC) detection. Although this formaldehyde derivative has been widely used in past tissue analysis, this paper describes an improved derivatisation procedure. The formation of the DNPH formaldehyde derivative has been shortened to 2 min and a stabilising buffer has been added to the derivative to increase its stability. The average recovery of free formaldehyde in spiked cod was 63% with an RSD of 15% over the range of 25-200 mg kg(-1) (n = 48). The HPLC procedure described here was also compared to a commercial qualitative procedure - a swab test for the determination of free formaldehyde in fish. Several positive samples were compared by both methods.

V2O5 encapsulated MWCNTs in 2D surface architecture: Complete solid-state bendable highly stabilized energy efficient supercapacitor device

NASA Astrophysics Data System (ADS)

Pandit, Bidhan; Dubal, Deepak P.; Gómez-Romero, Pedro; Kale, Bharat B.; Sankapal, Babasaheb R.

2017-03-01

A simple and scalable approach has been reported for V2O5 encapsulation over interconnected multi-walled carbon nanotubes (MWCNTs) network using chemical bath deposition method. Chemically synthesized V2O5/MWCNTs electrode exhibited excellent charge-discharge capability with extraordinary cycling retention of 93% over 4000 cycles in liquid-electrolyte. Electrochemical investigations have been performed to evaluate the origin of capacitive behavior from dual contribution of surface-controlled and diffusion-controlled charge components. Furthermore, a complete flexible solid-state, flexible symmetric supercapacitor (FSS-SSC) device was assembled with V2O5/MWCNTs electrodes which yield remarkable values of specific power and energy densities along with enhanced cyclic stability over liquid configuration. As a practical demonstration, the constructed device was used to lit the ‘VNIT’ acronym assembled using 21 LED’s.

Simple Verification of the Parabolic Shape of a Rotating Liquid and a Boat on Its Surface

ERIC Educational Resources Information Center

Sabatka, Z.; Dvorak, L.

2010-01-01

This article describes a simple and inexpensive way to create and to verify the parabolic surface of a rotating liquid. The liquid is water. The second part of the article deals with the problem of a boat on the surface of a rotating liquid. (Contains 1 table, 10 figures and 5 footnotes.)

Experimental setup for precise measurement of losses in high-temperature superconducting transformer

NASA Astrophysics Data System (ADS)

Janu, Z.; Wild, J.; Repa, P.; Jelinek, Z.; Zizek, F.; Peksa, L.; Soukup, F.; Tichy, R.

2006-10-01

A simple cryogenic system for testing of the superconducting power transformer was constructed. Thermal shielding is provided by additional liquid nitrogen bath instead of super-insulation. The system, together with use of a precise nitrogen liquid level meter, permitted calorimetric measurements of losses of the 8 kVA HTS transformer with a resolution of the order of 0.1 W.

Preparation of stir cake sorptive extraction based on polymeric ionic liquid for the enrichment of benzimidazole anthelmintics in water, honey and milk samples.

PubMed

Wang, Yulei; Zhang, Jie; Huang, Xiaojia; Yuan, Dongxing

2014-08-20

In this work, a new stir cake sorptive extraction (SCSE) using polymeric ionic liquid monolith as sorbent was prepared. The sorbent was obtained by in situ copolymerization of an ionic liquid, 1-allyl-3-methylimidazolium bis[(trifluoro methyl)sulfonyl]imide (AMII) and divinylbenzene (DB) in the presence of N,N-dimethylformamide. The influence of the content of ionic liquid and the porogen in the polymerization mixture on extraction performance was studied thoroughly. The physicochemical properties of the polymeric ionic liquid were characterized by infrared spectroscopy, elemental analysis, scanning electron microscopy and mercury intrusion porosimetry. The usefulness of SCSE-AMIIDB was demonstrated by the enrichment of trace benzimidazole anthelmintics. Several parameters affecting the extraction efficiency were investigated, and under the optimized conditions, a simple and effective method for the determination of trace benzimidazoles residues in water, milk and honey samples was established by coupling SCSE-AMIIDB with high performance liquid chromatography/diode array detection (SCSE-AMIIDB-HPLC/DAD). Results indicated that the limits of detection (S/N=3) for target compounds were 0.020-0.072 μg L(-1), 0.035-0.10 μg L(-1) and 0.026-0.076 μg L(-1) in water, milk and honey samples, respectively. In addition, an acceptable reproducibility was achieved by evaluating the repeatability and intermediate precision with relative standard deviations (RSD) of less than 9% and 11%, respectively. Finally, the established AMII-SCSE-HPLC/DAD method was successfully applied for the determination of benzimidazoles residues in milk, honey and environmental water samples. Recoveries obtained for the determination of benzimidazole anthelmintics in spiking samples ranged from 70.2% to 117.6%, with RSD below 12% in all cases. Copyright © 2014 Elsevier B.V. All rights reserved.

Liquid-vapor rectilinear diameter revisited

NASA Astrophysics Data System (ADS)

Garrabos, Y.; Lecoutre, C.; Marre, S.; Beysens, D.; Hahn, I.

2018-02-01

In the modern theory of critical phenomena, the liquid-vapor density diameter in simple fluids is generally expected to deviate from a rectilinear law approaching the critical point. However, by performing precise scannerlike optical measurements of the position of the SF6 liquid-vapor meniscus, in an approach much closer to criticality in temperature and density than earlier measurements, no deviation from a rectilinear diameter can be detected. The observed meniscus position from far (10 K ) to extremely close (1 mK ) to the critical temperature is analyzed using recent theoretical models to predict the complete scaling consequences of a fluid asymmetry. The temperature dependence of the meniscus position appears consistent with the law of rectilinear diameter. The apparent absence of the critical hook in SF6 therefore seemingly rules out the need for the pressure scaling field contribution in the complete scaling theoretical framework in this SF6 analysis. More generally, this work suggests a way to clarify the experimental ambiguities in the simple fluids for the near-critical singularities in the density diameter.

Sensitive and simple determination of zwitterionic morphine in human urine based on liquid-liquid micro-extraction coupled with surface-enhanced Raman spectroscopy.

PubMed

Yu, Borong; Cao, Chentai; Li, Pan; Mao, Mei; Xie, Qiwen; Yang, Liangbao

2018-08-15

Morphine, a kind of illicit drugs, is also one of the main heroin metabolites. In consideration of a noninvasive way to monitor and identify drug abuse during forensic cases, the urine samples are usually detected. Here, colloidal gold nanorods (Au NRs) were introduced to act as active substrate, because of the strong optical extinction and spectral tunability of the longitudinal surface plasmon resonance (SPR). Thus, well surface-enhanced Raman spectra of morphine even at low concentrations could be obtained by portable Raman spectrometer. For the complex matrix environment of urine, liquid-liquid micro-extraction (LLME), a simple and inexpensive pretreatment, was employed to avoid the interferences. And then, the coupled surface-enhanced Raman spectroscopy (SERS) can give full play to the advantages of high sensitivity and unique spectroscopic fingerprint. According to the zwitterionic structure and physicochemical parameters of morphine molecules, the pH value of urine sample was adjusted to about 9 by buffer solution (KOH/NaB 4 O 7 ) and the mixture of chloroform and isopropyl alcohol (V/V=9:1) was chosen as extractant. Moreover, such pretreatment was proved to be appropriate for separation and concentration of morphine from urine. The developed LLME-SERS method could provide a detection limit less than 1 ppm in the human urine environment and the whole process of detection just needed take 5-6 min. What's more, the results of urine samples from heroin users exhibited application value of the proposed technique. The excellent performance makes it promising to become a rapid, reliable, and on-spot analyzer, especially for public safety and healthcare. Copyright © 2018 Elsevier B.V. All rights reserved.

Quality evaluation of moluodan concentrated pill using high-performance liquid chromatography fingerprinting coupled with chemometrics.

PubMed

Tao, Lingyan; Zhang, Qing; Wu, Yongjiang; Liu, Xuesong

2016-12-01

In this study, a fast and effective high-performance liquid chromatography method was developed to obtain a fingerprint chromatogram and quantitative analysis simultaneously of four indexes including gallic acid, chlorogenic acid, albiflorin and paeoniflorin of the traditional Chinese medicine Moluodan Concentrated Pill. The method was performed by using a Waters X-bridge C 18 reversed phase column on an Agilent 1200S high-performance liquid chromatography system coupled with diode array detection. The mobile phase of the high-performance liquid chromatography method was composed of 20 mmol/L phosphate solution and acetonitrile with a 1 mL/min eluent velocity, under a detection temperature of 30°C and a UV detection wavelength of 254 nm. After the methodology validation, 16 batches of Moluodan Concentrated Pill were analyzed by this high-performance liquid chromatography method and both qualitative and quantitative evaluation results were achieved by similarity analysis, principal component analysis and hierarchical cluster analysis. The results of these three chemometrics were in good agreement and all indicated that batch 10 and batch 16 showed significant differences with the other 14 batches. This suggested that the developed high-performance liquid chromatography method could be applied in the quality evaluation of Moluodan Concentrated Pill. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.