Development and validation of a selective, sensitive and stability indicating UPLC-MS/MS method for rapid, simultaneous determination of six process related impurities in darunavir drug substance.

PubMed

A, Vijaya Bhaskar Reddy; Yusop, Zulkifli; Jaafar, Jafariah; Aris, Azmi B; Majid, Zaiton A; Umar, Khalid; Talib, Juhaizah

2016-09-05

In this study a sensitive and selective gradient reverse phase UPLC-MS/MS method was developed for the simultaneous determination of six process related impurities viz., Imp-I, Imp-II, Imp-III, Imp-IV, Imp-V and Imp-VI in darunavir. The chromatographic separation was performed on Acquity UPLC BEH C18 (50 mm×2.1mm, 1.7μm) column using gradient elution of acetonitrile-methanol (80:20, v/v) and 5.0mM ammonium acetate containing 0.01% formic acid at a flow rate of 0.4mL/min. Both negative and positive electrospray ionization (ESI) modes were operated simultaneously using multiple reaction monitoring (MRM) for the quantification of all six impurities in darunavir. The developed method was fully validated following ICH guidelines with respect to specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, robustness and sample solution stability. The method was able to quantitate Imp-I, Imp-IV, Imp-V at 0.3ppm and Imp-II, Imp-III, and Imp-VI at 0.2ppm with respect to 5.0mg/mL of darunavir. The calibration curves showed good linearity over the concentration range of LOQ to 250% for all six impurities. The correlation coefficient obtained was >0.9989 in all the cases. The accuracy of the method lies between 89.90% and 104.60% for all six impurities. Finally, the method has been successfully applied for three formulation batches of darunavir to determine the above mentioned impurities, however no impurity was found beyond the LOQ. This method is a good quality control tool for the trace level quantification of six process related impurities in darunavir during its synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

Targeted quantification of low ng/mL level proteins in human serum without immunoaffinity depletion

PubMed Central

Shi, Tujin; Sun, Xuefei; Gao, Yuqian; Fillmore, Thomas L.; Schepmoes, Athena A.; Zhao, Rui; He, Jintang; Moore, Ronald J.; Kagan, Jacob; Rodland, Karin D.; Liu, Tao; Liu, Alvin Y.; Smith, Richard D.; Tang, Keqi; Camp, David G.; Qian, Wei-Jun

2013-01-01

We recently reported an antibody-free targeted protein quantification strategy, termed high-pressure, high-resolution separations with intelligent selection and multiplexing (PRISM) for achieving significantly enhanced sensitivity using selected reaction monitoring (SRM) mass spectrometry. Integrating PRISM with front-end IgY14 immunoaffinity depletion, sensitive detection of targeted proteins at 50–100 pg/mL levels in human blood plasma/serum was demonstrated. However, immunoaffinity depletion is often associated with undesired losses of target proteins of interest. Herein we report further evaluation of PRISM-SRM quantification of low-abundance serum proteins without immunoaffinity depletion. Limits of quantification (LOQ) at low ng/mL levels with a median coefficient of variation (CV) of ~12% were achieved for proteins spiked into human female serum. PRISM-SRM provided >100-fold improvement in the LOQ when compared to conventional LC-SRM measurements. PRISM-SRM was then applied to measure several low-abundance endogenous serum proteins, including prostate-specific antigen (PSA), in clinical prostate cancer patient sera. PRISM-SRM enabled confident detection of all target endogenous serum proteins except the low pg/mL-level cardiac troponin T. A correlation coefficient >0.99 was observed for PSA between the results from PRISM-SRM and immunoassays. Our results demonstrate that PRISM-SRM can successful quantify low ng/mL proteins in human plasma or serum without depletion. We anticipate broad applications for PRISM-SRM quantification of low-abundance proteins in candidate biomarker verification and systems biology studies. PMID:23763644

Quantification of Sunscreen Ethylhexyl Triazone in Topical Skin-Care Products by Normal-Phase TLC/Densitometry

PubMed Central

Sobanska, Anna W.; Pyzowski, Jaroslaw

2012-01-01

Ethylhexyl triazone (ET) was separated from other sunscreens such as avobenzone, octocrylene, octyl methoxycinnamate, and diethylamino hydroxybenzoyl hexyl benzoate and from parabens by normal-phase HPTLC on silica gel 60 as stationary phase. Two mobile phases were particularly effective: (A) cyclohexane-diethyl ether 1 : 1 (v/v) and (B) cyclohexane-diethyl ether-acetone 15 : 1 : 2 (v/v/v) since apart from ET analysis they facilitated separation and quantification of other sunscreens present in the formulations. Densitometric scanning was performed at 300 nm. Calibration curves for ET were nonlinear (second-degree polynomials), with R > 0.998. For both mobile phases limits of detection (LOD) were 0.03 and limits of quantification (LOQ) 0.1 μg spot−1. Both methods were validated. PMID:22629203

Digital Protocol for Chemical Analysis at Ultralow Concentrations by Surface-Enhanced Raman Scattering.

PubMed

de Albuquerque, Carlos Diego L; Sobral-Filho, Regivaldo G; Poppi, Ronei J; Brolo, Alexandre G

2018-01-16

Single molecule surface-enhanced Raman spectroscopy (SM-SERS) has the potential to revolutionize quantitative analysis at ultralow concentrations (less than 1 nM). However, there are no established protocols to generalize the application of this technique in analytical chemistry. Here, a protocol for quantification at ultralow concentrations using SM-SERS is proposed. The approach aims to take advantage of the stochastic nature of the single-molecule regime to achieved lower limits of quantification (LOQ). Two emerging contaminants commonly found in aquatic environments, enrofloxacin (ENRO) and ciprofloxacin (CIPRO), were chosen as nonresonant molecular probes. The methodology involves a multivariate resolution curve fitting known as non-negative matrix factorization with alternating least-squares algorithm (NMF-ALS) to solve spectral overlaps. The key element of the quantification is to realize that, under SM-SERS conditions, the Raman intensity generated by a molecule adsorbed on a "hotspot" can be digitalized. Therefore, the number of SERS event counts (rather than SERS intensities) was shown to be proportional to the solution concentration. This allowed the determination of both ENRO and CIPRO with high accuracy and precision even at ultralow concentrations regime. The LOQ for both ENRO and CIPRO were achieved at 2.8 pM. The digital SERS protocol, suggested here, is a roadmap for the implementation of SM-SERS as a routine tool for quantification at ultralow concentrations.

Towards tributyltin quantification in natural water at the Environmental Quality Standard level required by the Water Framework Directive.

PubMed

Alasonati, Enrica; Fettig, Ina; Richter, Janine; Philipp, Rosemarie; Milačič, Radmila; Sčančar, Janez; Zuliani, Tea; Tunç, Murat; Bilsel, Mine; Gören, Ahmet Ceyhan; Fisicaro, Paola

2016-11-01

The European Union (EU) has included tributyltin (TBT) and its compounds in the list of priority water pollutants. Quality standards demanded by the EU Water Framework Directive (WFD) require determination of TBT at so low concentration level that chemical analysis is still difficult and further research is needed to improve the sensitivity, the accuracy and the precision of existing methodologies. Within the frame of a joint research project "Traceable measurements for monitoring critical pollutants under the European Water Framework Directive" in the European Metrology Research Programme (EMRP), four metrological and designated institutes have developed a primary method to quantify TBT in natural water using liquid-liquid extraction (LLE) and species-specific isotope dilution mass spectrometry (SSIDMS). The procedure has been validated at the Environmental Quality Standard (EQS) level (0.2ngL(-1) as cation) and at the WFD-required limit of quantification (LOQ) (0.06ngL(-1) as cation). The LOQ of the methodology was 0.06ngL(-1) and the average measurement uncertainty at the LOQ was 36%, which agreed with WFD requirements. The analytical difficulties of the method, namely the presence of TBT in blanks and the sources of measurement uncertainties, as well as the interlaboratory comparison results are discussed in detail. Copyright © 2016 Elsevier B.V. All rights reserved.

Development and validation of an LC-MS/MS method for the quantification of tiamulin, trimethoprim, tylosin, sulfadiazine and sulfamethazine in medicated feed.

PubMed

Patyra, Ewelina; Nebot, Carolina; Gavilán, Rosa Elvira; Cepeda, Alberto; Kwiatek, Krzysztof

2018-05-01

A new multi-compound method for the analysis of veterinary drugs, namely tiamulin, trimethoprim, tylosin, sulfadiazine and sulfamethazine was developed and validated in medicated feeds. After extraction, the samples were centrifuged, diluted in Milli-Q water, filtered and analysed by high performance liquid chromatography coupled to tandem mass spectrometry. The separation of the analytes was performed on a biphenyl column with a gradient of 0.1% formic acid in acetonitrile and 0.1% formic acid in Milli-Q water. Quantitative validation was done in accordance with the guidelines laid down in European Commission Decision 2002/657/EC. Method performances were evaluated by the following parameters: linearity (R 2  < 0.99), precision (repeatability <14% and within-laboratory reproducibility <24%), recovery (73.58-115.21%), sensitivity, limit of detection (LOD), limit of quantification (LOQ), selectivity and expanded measurement uncertainty (k. = 2). The validated method was successfully applied to the 2 medicated feeds obtained from the interlaboratory studies and feed manufactures from Spain in August 2017. In these samples, tiamulin, tylosin and sulfamethazine were detected at the concentration levels declared by the manufacturers. The developed method can therefore be successfully used to routinely control the content and homogeneity of these antibacterial substances in medicated feed. Abbreviations AAFCO - Association of American Feed Control Officials; TYL - tylosin; TIAM - tiamulin fumarate; TRIM - trimethoprim; SDZ - sulfadiazine; SMZ - sulfamethazine; UV - ultraviolet detector; FLD - fluorescence detector; HPLC - high performance liquid chromatography; MS/MS - tandem mass spectrometry; LOD - limit of detection; LOQ - limit of quantification; CV - coefficient of variation; SD - standard deviation; U - uncertainty.

Quantification of 4'-geranyloxyferulic acid, a new natural colon cancer chemopreventive agent, by HPLC-DAD in grapefruit skin extract.

PubMed

Genovese, S; Epifano, F; Carlucci, G; Marcotullio, M C; Curini, M; Locatelli, M

2010-10-10

Oxyprenylated natural products (isopentenyloxy-, geranyloxy- and the less spread farnesyloxy-compounds and their biosynthetic derivatives) represent a family of secondary metabolites that have been consider for years merely as biosynthetic intermediates of the most abundant C-prenylated derivatives. Many of the isolated oxyprenylated natural products were shown to exert in vitro and in vivo remarkable anti-cancer and anti-inflammatory effects. 4'-Geranyloxyferulic acid [3-(4'-geranyloxy-3'-methoxyphenyl)-2-trans-propenoic] has been discovered as a valuable chemopreventive agent of several types of cancer. After development of a high yield and "eco-friendly" synthetic scheme of this secondary metabolite, starting from cheap and non-toxic reagents and substrates, we developed a new HPLC-DAD method for its quantification in grapefruit skin extract. A preliminary study on C18 column showed the separation between GOFA and boropinic acid (having the same core but with an isopentenyloxy side chain), used as internal standard. The tested column were thermostated at 28+/-1 degrees C and the separation was achieved in gradient condition at a flow rate of 1 mL/min with a starting mobile phase of H(2)O:methanol (40:60, v/v, 1% formic acid). The limit of detection (LOD, S/N=3) was 0.5 microg/mL and the limit of quantification (LOQ, S/N=10) was 1 microg/mL. Matrix-matched standard curves showed linearity up to 75 microg/mL. In the analytical range the precision (RSD%) values were

Occurrence of perchlorate in drinking water and seawater in South Korea.

PubMed

Her, Namguk; Jeong, Hyunchan; Kim, Jongsung; Yoon, Yeomin

2011-08-01

Concentrations of perchlorate were determined by both liquid-chromatography-mass spectrometry (LC-MS) and ion chromatography tandem mass spectrometry (IC-MS/MS) in 520 tap-water, 48 bottled-water, and 9 seawater samples obtained or purchased from >100 different locations in South Korea. The method detection limits were 0.013 μg/L for LC-MS and 0.005 μg/L for IC-MS/MS, and the limits of quantification (LOQs) were 0.10 μg/L for LC-MS and 0.032 μg/L for IC-MS/MS. Perchlorate was detected in most (80%) of the tap-water samples, with concentrations higher than the LOQ; the concentrations ranged from <1.0 to 6.1 μg/L (mean 0.56). Perchlorate was detected by IC-MS/MS in many (n = 23) of the bottled-water samples, with concentrations higher then the LOQ, ranging from 0.04 to 0.29 μg/L (mean 0.07 ± 0.01). The concentrations of perchlorate in all seawater samples collected from the various locations were higher than the LOQ, with a mean concentration of 1.15 ± 0.01 μg/L (maximum 6.11 and minimum 0.11). This study provides further evidence that drinking-water sources have been contaminated by perchlorate. To the best of our knowledge, this is the first comprehensive study on perchlorate assessment in drinking water and seawater in South Korea.

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

PubMed

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

2015-03-01

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

Simultaneous quantification and identification of flavonoids, lignans, coumarin and amides in leaves of Zanthoxylum armatum using UPLC-DAD-ESI-QTOF-MS/MS.

PubMed

Bhatt, Vinod; Sharma, Sushila; Kumar, Neeraj; Sharma, Upendra; Singh, Bikram

2017-01-05

The current study presents isolation and characterization of twelve compounds including catechin (1), isovitexin (2), hesperidin (3), psoralin (4), eudesmin (5), kobusin (6), fargesin (7), sesamin (8), asarinin (9), planispine-A (10), α-sanshool (11) and vitexin (12), from the leaves of Zanthoxylum armatum. Further, two rapid and simple ultra performance liquid chromatography-diode array detection (UPLC-DAD) methods were developed for the simultaneous quantitative determination of isolated compounds from Z. armatum leaves. These analytical methods were validated for linearity, precision, accuracy, limit of detection (LOD) and limit of quantification (LOQ). The LOD and LOQ were in the range of 0.06-0.21μg/mL and 0.19-0.69μg/mL, respectively. The validated method was linear (R 2 ≥0.9906), precise in terms of peak area (intra-day RSDs <3.8% and inter-day RSDs <2.7%), and accurate (109.6-92.5%). This is the first report on the isolation and quantification of 1, 2, 4 and 12 in Z. armatum and 3 in Zanthoxylum genus. The methods: were successfully applied to assess the quality of samples collected from different locations of Himachal Pradesh during summer and winter season. The results demonstrated that flavonoids and furofuran lignans were the major constituents in Z. armatum leaves. The developed methods: were further applied for tandem electrospray ionization-mass spectrometry (UPLC-DAD-ESI-MS/MS) and total eighteen compounds were identified including phenolic acid, flavonoids, furofuran lignans, coumarin and isobutyl amides. Copyright © 2016 Elsevier B.V. All rights reserved.

Determination of lipophilic marine toxins in mussels. Quantification and confirmation criteria using high resolution mass spectrometry.

PubMed

Domènech, Albert; Cortés-Francisco, Nuria; Palacios, Oscar; Franco, José M; Riobó, Pilar; Llerena, José J; Vichi, Stefania; Caixach, Josep

2014-02-07

A multitoxin method has been developed for quantification and confirmation of lipophilic marine biotoxins in mussels by liquid chromatography coupled to high resolution mass spectrometry (HRMS), using an Orbitrap-Exactive HCD mass spectrometer. Okadaic acid (OA), yessotoxin, azaspiracid-1, gymnodimine, 13-desmethyl spirolide C, pectenotoxin-2 and Brevetoxin B were analyzed as representative compounds of each lipophilic toxin group. HRMS identification and confirmation criteria were established. Fragment and isotope ions and ion ratios were studied and evaluated for confirmation purpose. In depth characterization of full scan and fragmentation spectrum of the main toxins were carried out. Accuracy (trueness and precision), linearity, calibration curve check, limit of quantification (LOQ) and specificity were the parameters established for the method validation. The validation was performed at 0.5 times the current European Union permitted levels. The method performed very well for the parameters investigated. The trueness, expressed as recovery, ranged from 80% to 94%, the precision, expressed as intralaboratory reproducibility, ranged from 5% to 22% and the LOQs range from 0.9 to 4.8pg on column. Uncertainty of the method was also estimated for OA, using a certified reference material. A top-down approach considering two main contributions: those arising from the trueness studies and those coming from the precision's determination, was used. An overall expanded uncertainty of 38% was obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

Validated spectrofluorimetric method for the determination of tamsulosin in spiked human urine, pure and pharmaceutical preparations.

PubMed

Karasakal, A; Ulu, S T

2014-05-01

A novel, sensitive and selective spectrofluorimetric method was developed for the determination of tamsulosin in spiked human urine and pharmaceutical preparations. The proposed method is based on the reaction of tamsulosin with 1-dimethylaminonaphthalene-5-sulfonyl chloride in carbonate buffer pH 10.5 to yield a highly fluorescent derivative. The described method was validated and the analytical parameters of linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, precision, recovery and robustness were evaluated. The proposed method showed a linear dependence of the fluorescence intensity on drug concentration over the range 1.22 × 10(-7) to 7.35 × 10(-6)  M. LOD and LOQ were calculated as 1.07 × 10(-7) and 3.23 × 10(-7)  M, respectively. The proposed method was successfully applied for the determination of tamsulosin in pharmaceutical preparations and the obtained results were in good agreement with those obtained using the reference method. Copyright © 2013 John Wiley & Sons, Ltd.

Quantitative determination of rocuronium in human plasma by liquid chromatography-electrospray ionization mass spectrometry.

PubMed

Farenc, C; Enjalbal, C; Sanchez, P; Bressolle, F; Audran, M; Martinez, J; Aubagnac, J L

2001-02-23

Liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) was used for the quantification of the neuromuscular blocking agent rocuronium in human plasma. Verapamil was used as internal standard. The samples were subjected to a dichloromethane liquid-liquid extraction after ion pairing of the positively charged ammonium compound with iodide prior to LC-MS. Optimized conditions involved separation on a Symmetry Shield RP-18 column (50 x 2.1 mm, 3.5 microm) using a 15-min gradient from 10 to 90% acetonitrile in water containing 0.1% trifluoroacetic acid at 250 microl/min. Linear detector responses for standards were observed from 25 to 2,000 ng/ml. The extraction recovery averaged 59% for rocuronium and 83% for the internal standard. The limit of quantification (LOQ), using 500 microl of plasma, was 25 ng/ml. Precision ranged from 1.3 to 19% (LOQ), and accuracy was between 92 and 112%. In plasma samples, at 20 and 4 degrees C, rocuronium was stable at physiological pH for 4 h; frozen at -30 degrees C it was stable for at least 75 days. The method was found suitable for the analysis of samples collected during pharmacokinetic investigations in humans.

Species identification and quantification in meat and meat products using droplet digital PCR (ddPCR).

PubMed

Floren, C; Wiedemann, I; Brenig, B; Schütz, E; Beck, J

2015-04-15

Species fraud and product mislabelling in processed food, albeit not being a direct health issue, often results in consumer distrust. Therefore methods for quantification of undeclared species are needed. Targeting mitochondrial DNA, e.g. CYTB gene, for species quantification is unsuitable, due to a fivefold inter-tissue variation in mtDNA content per cell resulting in either an under- (-70%) or overestimation (+160%) of species DNA contents. Here, we describe a reliable two-step droplet digital PCR (ddPCR) assay targeting the nuclear F2 gene for precise quantification of cattle, horse, and pig in processed meat products. The ddPCR assay is advantageous over qPCR showing a limit of quantification (LOQ) and detection (LOD) in different meat products of 0.01% and 0.001%, respectively. The specificity was verified in 14 different species. Hence, determining F2 in food by ddPCR can be recommended for quality assurance and control in production systems. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

A HPLC method for the quantification of butyramide and acetamide at ppb levels in hydrogeothermal waters

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

Gracy Elias; Earl D. Mattson; Jessica E. Little

A quantitative analytical method to determine butyramide and acetamide concentrations at the low ppb levels in geothermal waters has been developed. The analytes are concentrated in a preparation step by evaporation and analyzed using HPLC-UV. Chromatographic separation is achieved isocratically with a RP C-18 column using a 30 mM phosphate buffer solution with 5 mM heptane sulfonic acid and methanol (98:2 ratio) as the mobile phase. Absorbance is measured at 200 nm. The limit of detection (LOD) for BA and AA were 2.0 {mu}g L{sup -1} and 2.5 {mu}g L{sup -1}, respectively. The limit of quantification (LOQ) for BA andmore » AA were 5.7 {mu}g L{sup -1} and 7.7 {mu}g L{sup -1}, respectively, at the detection wavelength of 200 nm. Attaining these levels of quantification better allows these amides to be used as thermally reactive tracers in low-temperature hydrogeothermal systems.« less

Validation of a Thin-Layer Chromatography for the Determination of Hydrocortisone Acetate and Lidocaine in a Pharmaceutical Preparation

PubMed Central

Dołowy, Małgorzata; Kulpińska-Kucia, Katarzyna; Pyka, Alina

2014-01-01

A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform + acetone + ammonia (25%) in volume composition 8 : 2 : 0.1 and silica gel 60F254 plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of 3.75 ÷ 12.50 μg·spot−1, and from 1.00 ÷ 2.50 μg·spot−1 for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198 μg·spot−1 and LOD is 0.066 μg·spot−1. LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090 μg·spot−1, respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia. PMID:24526880

Validation of a thin-layer chromatography for the determination of hydrocortisone acetate and lidocaine in a pharmaceutical preparation.

PubMed

Dołowy, Małgorzata; Kulpińska-Kucia, Katarzyna; Pyka, Alina

2014-01-01

A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform+acetone+ammonia (25%) in volume composition 8:2:0.1 and silica gel 60F254 plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of 3.75÷12.50  μg·spot(-1), and from 1.00÷2.50  μg·spot(-1) for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198  μg·spot(-1) and LOD is 0.066  μg·spot(-1). LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090  μg·spot(-1), respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia.

Exposure to airborne organophosphates originating from hydraulic and turbine oils among aviation technicians and loaders.

PubMed

Solbu, Kasper; Daae, Hanne Line; Thorud, Syvert; Ellingsen, Dag Gunnar; Lundanes, Elsa; Molander, Paal

2010-12-01

This study describes the potential for occupational exposure to organophosphates (OPs) originating from turbine and hydraulic oils, among ground personnel within the aviation industry. The OPs tri-n-butyl phosphate (TnBP), dibutyl phenyl phosphate (DBPP), triphenyl phosphate (TPP) and tricresyl phosphate (TCP) have been emphasized due to their use in such oils. Oil aerosol/vapor and total volatile organic compounds (tVOCs) in air were also determined. In total, 228 and 182 OPs and oil aerosol/vapor samples from technician and loader work tasks during work on 42 and 21 aircrafts, respectively, were collected in pairs. In general, the measured exposure levels were below the limit of quantification (LOQ) for 84%/98% (oil aerosol) and 82%/90% (TCP) of the samples collected during technician/loader work tasks. The air concentration ranges for all samples related to technician work were

One Novel Multiple-Target Plasmid Reference Molecule Targeting Eight Genetically Modified Canola Events for Genetically Modified Canola Detection.

PubMed

Li, Zhuqing; Li, Xiang; Wang, Canhua; Song, Guiwen; Pi, Liqun; Zheng, Lan; Zhang, Dabing; Yang, Litao

2017-09-27

Multiple-target plasmid DNA reference materials have been generated and utilized as good substitutes of matrix-based reference materials in the analysis of genetically modified organisms (GMOs). Herein, we report the construction of one multiple-target plasmid reference molecule, pCAN, which harbors eight GM canola event-specific sequences (RF1, RF2, MS1, MS8, Topas 19/2, Oxy235, RT73, and T45) and a partial sequence of the canola endogenous reference gene PEP. The applicability of this plasmid reference material in qualitative and quantitative PCR assays of the eight GM canola events was evaluated, including the analysis of specificity, limit of detection (LOD), limit of quantification (LOQ), and performance of pCAN in the analysis of various canola samples, etc. The LODs are 15 copies for RF2, MS1, and RT73 assays using pCAN as the calibrator and 10 genome copies for the other events. The LOQ in each event-specific real-time PCR assay is 20 copies. In quantitative real-time PCR analysis, the PCR efficiencies of all event-specific and PEP assays are between 91% and 97%, and the squared regression coefficients (R 2 ) are all higher than 0.99. The quantification bias values varied from 0.47% to 20.68% with relative standard deviation (RSD) from 1.06% to 24.61% in the quantification of simulated samples. Furthermore, 10 practical canola samples sampled from imported shipments in the port of Shanghai, China, were analyzed employing pCAN as the calibrator, and the results were comparable with those assays using commercial certified materials as the calibrator. Concluding from these results, we believe that this newly developed pCAN plasmid is one good candidate for being a plasmid DNA reference material in the detection and quantification of the eight GM canola events in routine analysis.

A Limited Survey of Heavy Metal Concentrations in Fresh and Frozen Cuttlefish Ink and Mantle Used As Food.

PubMed

Conficoni, Daniele; Alberghini, Leonardo; Bissacco, Elisa; Contiero, Barbara; Giaccone, Valerio

2018-02-01

Cuttlefish ink is consumed as a delicacy worldwide. The current study is the first assessment of heavy metal concentrations in cuttlefish ink versus mantle under different storage methods. A total of 212 samples (64 of fresh mantle, 42 of frozen mantle, 64 of fresh ink, and 42 of frozen ink) were analyzed for the detection of the following heavy metals: arsenic (As), chromium (Cr), iron (Fe), lead (Pb), mercury (Hg), and cadmium (Cd). The median As concentrations were 12.9 mg/kg for fresh mantle, 8.63 mg/kg for frozen mantle, 10.8 mg/kg for frozen ink, and 0.41 mg/kg for fresh ink. The median Cr concentrations were 0.06 mg/kg for fresh mantle and frozen ink, 0.03 mg/kg for frozen mantle, and below the limit of quantification (LOQ) for fresh ink. The median Fe concentrations were 4.08 mg/kg for frozen ink, 1.51 mg/kg for fresh mantle, 0.73 mg/kg for frozen mantle, and below the LOQ for fresh ink. The median Pb concentrations of almost all samples were below the LOQ; only two frozen ink, one fresh ink, one frozen mantle, and one fresh mantle sample exceeded the limit stipulated by the European Union. The Hg concentrations were statistically similar among the four categories of samples; the median Hg concentrations were below the LOQ, and the maximum concentrations were found in frozen ink, at 1.62 mg/kg. The median Cd concentrations were 0.69 mg/kg for frozen ink and 0.11 mg/kg for frozen mantle, fresh mantle and fresh ink concentrations were below the LOQ, and in 11.3% of the tested samples, Cd concentrations were higher than the European Union limit. The probability of samples having a Cd concentration above the legal limit was 35.75 times higher in frozen than in fresh products. Fresh ink had significantly lower concentrations of As, Cr, Fe, and Cd, but the concentrations of Hg and Pb were not significantly different from those of other products. Frozen ink had significantly higher concentrations of Cd, Cr, and Fe, but concentrations of As were lower than those in fresh mantle, pointing out a possible role for the freezing process and for different fishing zones as risk factors for heavy metal contamination.

Targeted quantification of low ng/mL level proteins in human serum without immunoaffinity depletion

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

Shi, Tujin; Sun, Xuefei; Gao, Yuqian

2013-07-05

We recently reported an antibody-free targeted protein quantification strategy, termed high-pressure, high-resolution separations with intelligent selection and multiplexing (PRISM) for achieving significantly enhanced sensitivity using selected reaction monitoring (SRM) mass spectrometry. Integrating PRISM with front-end IgY14 immunoaffinity depletion, sensitive detection of targeted proteins at 50-100 pg/mL levels in human blood plasma/serum was demonstrated. However, immunoaffinity depletion is often associated with undesired losses of target proteins of interest. Herein we report further evaluation of PRISM-SRM quantification of low-abundance serum proteins without immunoaffinity depletion and the multiplexing potential of this technique. Limits of quantification (LOQs) at low ng/mL levels with a medianmore » CV of ~12% were achieved for proteins spiked into human female serum using as little as 2 µL serum. PRISM-SRM provided up to ~1000-fold improvement in the LOQ when compared to conventional SRM measurements. Multiplexing capability of PRISM-SRM was also evaluated by two sets of serum samples with 6 and 21 target peptides spiked at the low attomole/µL levels. The results from SRM measurements for pooled or post-concatenated samples were comparable to those obtained from individual peptide fractions in terms of signal-to-noise ratios and SRM peak area ratios of light to heavy peptides. PRISM-SRM was applied to measure several ng/mL-level endogenous plasma proteins, including prostate-specific antigen, in clinical patient sera where correlation coefficients > 0.99 were observed between the results from PRISM-SRM and ELISA assays. Our results demonstrate that PRISM-SRM can be successfully used for quantification of low-abundance endogenous proteins in highly complex samples. Moderate throughput (50 samples/week) can be achieved by applying the post-concatenation or fraction multiplexing strategies. We anticipate broad applications for targeted PRISM-SRM quantification of low-abundance cellular proteins in systems biology studies as well as candidate biomarkers in biofluids.« less

Cannabis Use Surveillance by Sweat Analysis.

PubMed

Gambelunghe, Cristiana; Fucci, Nadia; Aroni, Kyriaki; Bacci, Mauro; Marcelli, Antonio; Rossi, Riccardo

2016-10-01

Sweat testing, an alternative matrix for establishing drug abuse, offers additional benefits to the more common biological samples. The authors developed a procedure using gas chromatography-mass spectrometry to test for Δ9-tetrahydrocannabinol, 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid, cannabinol (CBN), and cannabidiol (CBD) in a sweat patch. The results were compared with urine and hair sample results. Urine, hair, and sweat samples were simultaneously collected from 12 patients who were involved, respectively, in forensic case and monitoring abuse. Selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), recovery, intraday and interday imprecision, and inaccuracy of the quantification procedure were validated. LODs in hair were 0.05 ng/mg for Δ9-tetrahydrocannabinol, CBN, and CBD, and 0.005 ng/mg for 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid. The LOD for sweat was 0.30 ng/patch for all substances. The LOQ in hair was 0.1 ng/mg for Δ9-tetrahydrocannabinol, CBN, and CBD, and 0.01 ng/mg for 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid. The LOQ was 0.4 ng/patch in sweat for each analyte. Cannabinoid in urine was determined by means of immunochemical screening (cutoff 11-nor-Δ-tetrahydrocannabinol-9-carboxylic acid 50 ng/mL). All subjects tested positive for 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid and Δ9-tetrahydrocannabinol in urine and hair. In sweat samples, Δ9-tetrahydrocannabinol was found in all patches (0.4-2.0 ng/patch); 6 cases were positive for CBN (0.4-0.5 ng/patch) and 3 for CBD (0.4-0.6 ng/patch); 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid was never detected in patches. Present sweat analysis results integrated the information from hair and urine and showed that sweat analysis is a suitable, noninvasive method for monitoring compliance with rehabilitation therapy and for detecting recent cumulative use of cannabinoids.

Quality survey of natural mineral water and spring water sold in France: Monitoring of hormones, pharmaceuticals, pesticides, perfluoroalkyl substances, phthalates, and alkylphenols at the ultra-trace level.

PubMed

Le Coadou, Laurine; Le Ménach, Karyn; Labadie, Pierre; Dévier, Marie-Hélène; Pardon, Patrick; Augagneur, Sylvie; Budzinski, Hélène

2017-12-15

The aim of the present study, one of the most complete ever performed in France, was to carry out an extensive survey on the potential presence of a large amount of emerging contaminants in 40 French bottled waters, including parent compounds and metabolites. The studied samples represented 70% of the French bottled water market in volume. Six classes of compounds were investigated, most of them being unregulated in bottled waters: pesticides and their transformation products (118), pharmaceutical substances (172), hormones (11), alkylphenols (APs) (8), phthalates (11) and perfluoroalkyl substances (PFAS) (10). One of the objectives of this work was to achieve low and reliable limits of quantification (LOQs) (87% of the LOQs were below 10ng/L) using advanced analytical technologies and reliable sample preparation methodologies, including stringent quality controls. Among the 14,000 analyses performed, 99.7% of the results were below the LOQs. None of the hormones, pharmaceutical substances and phthalates were quantified. Nineteen compounds out of the 330 investigated were quantified in 11 samples. Eleven were pesticides including 7 metabolites, 6 were PFAS and 2 were APs. As regards pesticides, their sum was at least twice lower than the quality standards applicable for bottled waters in France. The presence of a majority of pesticide metabolites suggested a former use in the recharge areas of the exploited aquifers. The quantification of a few unregulated emerging compounds at the nano-trace level, such as PFAS, raised the issue of their potential sources, including long-range atmospheric transport and deposition. This study confirmed that the groundwater aquifers exploited for bottling were well-preserved from chemicals, as compared to less geologically protected groundwaters, and also underlined the need to pursue the protection policies implemented in recharge areas in order to limit the anthropogenic pressure. Copyright © 2016. Published by Elsevier B.V.

A high-performance liquid chromatographic-tandem mass spectrometric method for the determination of ethyl glucuronide and ethyl sulfate in urine validated according to forensic guidelines.

PubMed

Albermann, M E; Musshoff, F; Madea, B

2012-01-01

Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are powerful markers for alcohol intake and abuse. Several analytical procedures for the quantification of EtG and EtG in serum and urine have been developed so far. Many of the published methods show limits of detections (LODs) or limits of quantifications (LOQs) for EtG in urine within the range of 0.1 mg/L or higher. Since this is the actual cutoff value for proving abstinence in Germany, problems may occur if urine samples are highly diluted. In this paper, the validation of a highly sensitive, fast and simple LC-MS-MS for the determination of EtG and EtS in urine is described. The calibration curves for EtG and EtS is linear over the whole range (0.025-2.0 mg/L). Very low detection limits can be achieved (LOD: EtG 0.005 mg/L, EtS 0.005 mg/L; and LOQ: EtG 0.019 mg/L, EtS 0.015 mg/L). All data for selectivity, precision and accuracy, recovery, as well as for the processed sample and the freeze/thaw stability, comply with the guidelines of the German Society of Toxicological and Forensic Chemistry. Strong matrix-related effects can be compensated for by using an internal standard. Finally, the applicability of the procedure is proven by analysis of 87 human urine samples and by successful participation in interlaboratory comparison tests. © The Author [2011]. Published by Oxford University Press. All rights reserved.

Development and validation of a reversed phase liquid chromatographic method for analysis of oxytetracycline and related impurities.

PubMed

Kahsay, Getu; Shraim, Fairouz; Villatte, Philippe; Rotger, Jacques; Cassus-Coussère, Céline; Van Schepdael, Ann; Hoogmartens, Jos; Adams, Erwin

2013-03-05

A simple, robust and fast high-performance liquid chromatographic method is described for the analysis of oxytetracycline and its related impurities. The principal peak and impurities are all baseline separated in 20 min using an Inertsil C₈ (150 mm × 4.6 mm, 5 μm) column kept at 50 °C. The mobile phase consists of a gradient mixture of mobile phases A (0.05% trifluoroacetic acid in water) and B (acetonitrile-methanol-tetrahydrofuran, 80:15:5, v/v/v) pumped at a flow rate of 1.3 ml/min. UV detection was performed at 254 nm. The developed method was validated for its robustness, sensitivity, precision and linearity in the range from limit of quantification (LOQ) to 120%. The limits of detection (LOD) and LOQ were found to be 0.08 μg/ml and 0.32 μg/ml, respectively. This method allows the separation of oxytetracycline from all known and 5 unknown impurities, which is better than previously reported in the literature. Moreover, the simple mobile phase composition devoid of non-volatile buffers made the method suitable to interface with mass spectrometry for further characterization of unknown impurities. The developed method has been applied for determination of related substances in oxytetracycline bulk samples available from four manufacturers. The validation results demonstrate that the method is reliable for quantification of oxytetracycline and its impurities. Copyright © 2012 Elsevier B.V. All rights reserved.

Rapid analytical procedure for determination of mineral oils in edible oil by GC-FID.

PubMed

Wrona, Magdalena; Pezo, Davinson; Nerin, Cristina

2013-12-15

A procedure for the determination of mineral oils in edible oil has been fully developed. The procedure consists of using a sulphuric acid-impregnated silica gel (SAISG) glass column to eliminate the fat matter. A chemical combustion of the fatty acids takes place, while the mineral oils are not affected by the sulphuric acid. The column is eluted with hexane using a vacuum pump and the final extract is concentrated and analysed by gas chromatography (GC) with flame ionisation detector (FID). The detection limit (LOD) and the quantification limit (LOQ) in hexane were 0.07 and 0.21 μg g(-1) respectively and the LOQ in vegetable oil was 1 μg g(-1). Only a few minutes were necessary for sample treatment to have a clean extract. The efficiency of the process, measured through the recoveries from spiked samples of edible oil was higher than 95%. The procedure has been applied to determine mineral oil in olive oil from the retailed market. Copyright © 2013 Elsevier Ltd. All rights reserved.

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.

Development of a field method for measuring manganese in welding fume.

PubMed

Dale Marcy, A; Drake, Pamela L

2007-11-01

Workers who perform routine welding tasks are potentially exposed to fume that may contain manganese. Manganese may cause respiratory problems and is implicated in causing the occurrence of Parkinson-like symptoms. In this study, a field colorimetric method for extracting and measuring manganese in welding fume was developed. The method uses ultrasonic extraction with an acidic hydrogen peroxide solution to extract welding fume collected on polyvinyl chloride filters. Commercially available pre-packaged reagents are used to produce a colored solution, created by a reaction of manganese(ii) with 1-(2-pyridylazo)-2-naphthol. Absorbance measurements are then made using a portable spectrophotometer. The method detection limit and limit of quantification (LOQ) were 5.2 microg filter(-1) and 17 microg filter(-1), respectively, with a dynamic range up to 400 microg filter(-1). When the results are above the LOQ for the colorimetric method, the manganese masses are equivalent to those measured by the International Organization for Standardization Method 15202-2, which employs a strong acid digestion and analysis using inductively coupled plasma-optical emission spectrometry.

Second Trimester Amniotic Fluid Bisphenol A Concentration is Associated with Decreased Birth Weight in Term Infants

PubMed Central

Pinney, Sara E.; Mesaros, Clementina A.; Snyder, Nathaniel W.; Busch, Christine M.; Xiao, Rui; Aijaz, Sara; Ijaz, Naila; Blair, Ian A.; Manson, Jeanne M.

2016-01-01

Bisphenol A (BPA) is an endocrine disrupting chemical with ubiquitous environmental exposure. Animal studies have demonstrated that in utero BPA exposure leads to increased adult body weight. Our aim was to characterize human fetal BPA exposure by measuring BPA concentration in second trimester amniotic fluid (AF) samples and to study its relationship with birth weight (BW) in full term infants. To achieve these goals, we developed a total BPA assay utilizing derivatization with pentafluorobenzyl followed by analysis with LC-ECAPCI-MS/MS with a limit of detection of 0.08 ng/mL and limit of quantification (LOQ) of 0.25 ng/mL. The mean BW of infants with AF BPA 0.40-2.0 ng/mL was 241.8 grams less than infants with AF BPA less than the LOQ after controlling for covariates (p=0.049). No effect was seen outside this range indicating a non-monotonic effect. Our data suggest that low level BPA exposure in utero decreases BW and needs further study. PMID:27829162

Dissipation rate study and pre-harvest intervals calculation of imidacloprid and oxamyl in exported Egyptian green beans and chili peppers after pestigation treatment.

PubMed

Hanafi, Ahmad; Dasenaki, Marilena; Bletsou, Anna; Thomaidis, Nikolaos S

2018-02-01

Two QuEChERS-based methods were developed and validated, using liquid chromatography-tandem mass spectrometric detection, in order to accurately determine residues of imidacloprid and oxamyl in green beans and chili peppers after treatment via irrigation system under field conditions in Egyptian farms. The validation included experiments for specificity, linearity, trueness, precision, matrix effect and limits of detection and quantification according to European Commission standards. The dissipation rates of both pesticides in green beans and chili peppers were studied and the pre-harvest intervals (PHIs) were calculated. The LOQ values of imidacloprid were 0.47 and 2.6μg/kg in green beans and chili peppers, respectively, while for oxamyl the LOQs were 2.9 and 0.67μg/kg, respectively. No PHI of imidacloprid is required, while for oxamyl it was found that still after 21days, its residues' concentration on both crops was significantly higher than the maximum residue limit. Copyright © 2017 Elsevier Ltd. All rights reserved.

Design and characterization of a direct ELISA for the detection and quantification of leucomalachite green

PubMed Central

Singh, Gurmit; Koerner, Terence; Gelinas, Jean-Marc; Abbott, Michael; Brady, Beth; Huet, Anne-Catherine; Charlier, Caroline; Delahaut, Philippe; Godefroy, Samuel Benrejeb

2011-01-01

Malachite green (MG), a member of the N-methylated triphenylmethane class of dyes, has long been used to control fungal and protozoan infections in fish. MG is easily absorbed by fish during waterborne exposure and is rapidly metabolized into leucomalachite green (LMG), which is known for its long residence time in edible fish tissue. This paper describes the development of an enzyme-linked immunosorbent assay (ELISA) for the detection and quantification of LMG in fish tissue. This development includes a simple and versatile method for the conversion of LMG to monodesmethyl-LMG, which is then conjugated to bovine serum albumin (BSA) to produce an immunogenic material. Rabbit polyclonal antibodies are generated against this immunogen, purified and used to develop a direct competitive enzyme-linked immunosorbent assay (ELISA) for the screening and quantification of LMG in fish tissue. The assay performed well, with a limit of detection (LOD) and limit of quantification (LOQ) of 0.1 and 0.3 ng g−1 of fish tissue, respectively. The average extraction efficiency from a matrix of tilapia fillets was approximately 73% and the day-to-day reproducibility for these extractions in the assay was between 5 and 10%. PMID:21623496

Development of a LC-MS method for simultaneous determination of amoxicillin and metronidazole in human serum using hydrophilic interaction chromatography (HILIC).

PubMed

Kathriarachchi, Udani L; Vidhate, Sagar S; Al-Tannak, Naser; Thomson, Alison H; da Silva Neto, Michael J J; Watson, David G

2018-07-01

A method was developed for the determination of amoxicillin and metronidazole in human serum. The procedure used was hydrophilic interaction chromatography (HILIC) followed by mass spectrometric (MS) detection. Chromatographic separation was achieved on a ZIC-HILIC column and the mobile phase consisted of a mixture of 0.1% (v/v) formic acid in water and 0.1% (v/v) formic acid in acetonitrile. The method was validated with regard to selectivity, accuracy, precision, calibration, lower limit of quantification (LOQ), extraction recovery and matrix effect. The LOQs were 0.0138 and 0.008 μg/ml for amoxicillin and metronidazole respectively, while for quantification purposes linearity was achieved in the range of 0.1 μg/ml to 6.4 μg/ml for both drugs with correlation coefficients >0.9990. The intraday precision (expressed as %RSD) and the accuracy (expressed as the % deviation from the nominal value) was <15% for both antibiotics at all QC levels. Extraction recoveries for both drugs and internal standards were >80%, while a considerable matrix effect (<60%) was observed for amoxicillin. Finally, the method was applied to the determination of amoxicillin and metronidazole concentrations in serum for 20 patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Determination of endrin and δ-keto endrin in five food products of animal origin using GC-μECD: A modified QuEChERS approach to traditional detection.

PubMed

Rahman, Md Musfiqur; Lee, Han Sol; Abd El-Aty, A M; Kabir, Md Humayun; Chung, Hyung Suk; Park, Jong-Hyouk; Kim, Mi-Ra; Kim, Ji-Hyun; Shin, Ho-Chul; Shin, Sung Shik; Shim, Jae-Han

2018-10-15

A simple quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based method was developed for the analysis of endrin and its metabolite, δ-keto endrin, in five animal-derived food products (chicken, pork, beef, egg, and milk) using a gas chromatography-micro electron capture detector (GC-μECD). Samples were extracted with acidified acetonitrile, salted out with magnesium sulfate and sodium acetate, and finally purified with a dual layer solid-phase extraction cartridge (SPE) that contains both Supelclean ENVI-Carb (upper layer) and primary secondary amine (lower layer) SPE sorbents. A seven-point external calibration curve was constructed both for the solvent and matrix for both compounds. Good linearity was achieved for both analytes, with coefficients of determination (R 2 ) ≥ 0.9960. The limits of detection (LODs) were 0.003 mg/kg, whereas the limits of quantification (LOQ) were 0.01 mg/kg, which were 10 times lower than the extraneous maximum residue limit (EMRL) designated by CODEX Alimentarius for the specified matrices. The method was validated via recovery performances in triplicates, with three fortification levels equivalent to LOQ, 2 × LOQ, and 10 × LOQ. The method provided excellent recoveries, ranging between 75.63 and 117.92%, with relative standard deviations (RSD) ≤ 8.52% for both analytes in various matrices. The developed method was successfully applied to monitor market samples collected from 20 different places throughout the Republic of Korea, and none of the tested analytes were found in the analyzed samples. Conclusively, we could propose that the current method can be used for routine analysis of endrin and δ-keto endrin in any type of fatty food matrix. Copyright © 2018 Elsevier Ltd. All rights reserved.

Determination of perfluoroalkylated substances (PFASs) in drinking water from the Netherlands and Greece.

PubMed

Zafeiraki, Effrosyni; Costopoulou, Danae; Vassiliadou, Irene; Leondiadis, Leondios; Dassenakis, Emmanouil; Traag, Wim; Hoogenboom, Ron L A P; van Leeuwen, Stefan P J

2015-01-01

In the present study 11 perfluoroalkylated substances (PFASs) were analysed in drinking tap water samples from the Netherlands (n = 37) and from Greece (n = 43) by applying LC-MS/MS and isotope dilution. PFASs concentrations above the limit of quantification, LOQ (0.6 ng/l) were detected in 20.9% of the samples from Greece. Total PFAS concentrations ranged between 8) were only rarely detected. In the drinking water samples from the eastern part of the Netherlands, where drinking water is sourced from groundwater reservoirs, no PFASs were detected. This demonstrates that exposure to PFASs through drinking water in the Netherlands is dependent on the source. Additionally, five samples of bottled water from each country were analysed in the current study, with all of them originating from ground wells. In these samples, all PFASs were below the LOQ.

Persistent organochlorines in 13 shark species from offshore and coastal waters of Korea: Species-specific accumulation and contributing factors.

PubMed

Lee, Hyun-Kyung; Jeong, Yunsun; Lee, Sunggyu; Jeong, Woochang; Choy, Eun-Jung; Kang, Chang-Keun; Lee, Won-Chan; Kim, Sang-Jo; Moon, Hyo-Bang

2015-05-01

Data on persistent organochlorines (OCs) in sharks are scarce. Concentrations of OCs such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were determined in the muscle tissue of 13 shark species (n=105) collected from offshore (Indian and Pacific Oceans) and coastal waters of Korea, to investigate species-specific accumulation of OCs and to assess the potential health risks associated with consumption of shark meat. Overall OC concentrations were highly variable not only among species but also within the same species of shark. The concentrations of PCBs, DDTs, chlordanes, hexachlorobenzene, and heptachlor in all shark species ranged from

Colorimetric and fluorescent detection of hydrazine with high sensitivity and excellent selectivity

NASA Astrophysics Data System (ADS)

Shi, Bingjie; Qi, Sujie; Yu, Mingming; Liu, Chunxia; Li, Zhanxian; Wei, Liuhe; Ni, Zhonghai

2018-01-01

It is critical to develop probes for rapid, selective, and sensitive detection of the highly toxic hydrazine in both environmental and biological science. In this work, under mild condition, a novel colorimetric and off-on fluorescent probe was synthesized for rapid recognition of hydrazine with excellent selectivity over other various species including some biological species, metal ions and anions. The limit of quantification (LOQ) value was 1.5 × 10- 4 M-3.2 × 10- 3 M (colorimetric method) and 1.5 × 10- 4 M - 3.2 × 10- 3 M (fluorescent method) with as low as detection limit of 46.2 μM.

One-step liquid-liquid extraction of cocaine from urine samples for gas chromatographic analysis.

PubMed

Farina, Marcelo; Yonamine, Maurício; Silva, Ovandir A

2002-07-17

An improved technique for cocaine extraction from urine samples for gas chromatographic (GC) analysis is described. Employing a simple liquid-liquid extraction (LLE) of cocaine with a mixture of ethyl ether:isopropanol (9:1) the method presents a mean recovery of 74.49%. Limit of detection (LOD) and limit of quantification (LOQ) were 5 and 20 ng/ml, respectively. The method is highly precise (coefficient of variation (CV) <8%) and linear from 20 to 2000 ng/ml. It can he applied to detect the presence of cocaine in urine as a marker of its recent use in drug abuse treatment protocols.

The disappearance rate and risk assessment of thiacloprid residues in Asian pear using liquid chromatography confirmed with tandem mass spectrometry.

PubMed

Kabir, Md Humayun; Abd El-Aty, A M; Rahman, Md Musfiqur; Kim, Sung-Woo; Choi, Jeong-Heui; Lee, Young-Jun; Truong, Lieu T B; Lee, Kang-Bong; Kim, Mi-Ra; Shin, Ho-Chul; Shim, Jae-Han

2017-05-01

This study was undertaken to quantify the residue levels and propose the dissipation kinetics of thiacloprid formulated as suspension concentrate in field-incurred Asian pears grown under two different open-field conditions. Samples were extracted with 20% distilled water in acetonitrile; partitioned with brine water and dichloromethane; and purified with a Florisil solid phase extraction cartridge. The analyte was identified with an LC ultraviolet detector, and field-incurred samples were confirmed using LC-MS/MS. The calibration curve was linear over the range 0.05-5.0 mg/L with a satisfactory coefficient of determination (R 2  = 0.9994). The limits of detection and limits of quantification (LOQ) were 0.003 and 0.01 mg/kg, respectively. The recovery rate fortified to blank samples at LOQ, 10× LOQ, and the maximum residue limit (MRL) were between 73.7 and 86.2% with relative standard deviation ≤9.0%. The residual concentrations at both sites were considerably lower than the MRL (0.7 mg/kg) set by the Korean Ministry of Food Drug Safety, with biological half-lives of 5.0 and 7.4 days, for sites 1 and 2, respectively. From the pre-harvest residue limit curve, it was predicted that if the residues were <1.13 or 1.40 mg/kg 10 days before harvest, the residue level would be lower than the MRL during harvest. Risk assessment on day 0 showed an acceptable daily intake (%) of 13.0% and 11.0% for sites 1 and site 2, respectively, which indicates that the residual amounts are not hazardous to the Korean population. Copyright © 2016 John Wiley & Sons, Ltd.

Multiple headspace-solid-phase microextraction: an application to quantification of mushroom volatiles.

PubMed

Costa, Rosaria; Tedone, Laura; De Grazia, Selenia; Dugo, Paola; Mondello, Luigi

2013-04-03

Multiple headspace-solid phase microextraction (MHS-SPME) followed by gas chromatography/mass spectrometry (GC-MS) and flame ionization detection (GC-FID) was applied to the identification and quantification of volatiles released by the mushroom Agaricus bisporus, also known as champignon. MHS-SPME allows to perform quantitative analysis of volatiles from solid matrices, free of matrix interferences. Samples analyzed were fresh mushrooms (chopped and homogenized) and mushroom-containing food dressings. 1-Octen-3-ol, 3-octanol, 3-octanone, 1-octen-3-one and benzaldehyde were common constituents of the samples analyzed. Method performance has been tested through the evaluation of limit of detection (LoD, range 0.033-0.078 ng), limit of quantification (LoQ, range 0.111-0.259 ng) and analyte recovery (92.3-108.5%). The results obtained showed quantitative differences among the samples, which can be attributed to critical factors, such as the degree of cell damage upon sample preparation, that are here discussed. Considerations on the mushrooms biochemistry and on the basic principles of MHS analysis are also presented. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous ultra-high-pressure liquid chromatography-tandem mass spectrometry determination of amphetamine and amphetamine-like stimulants, cocaine and its metabolites, and a cannabis metabolite in surface water and urban wastewater.

PubMed

Bijlsma, Lubertus; Sancho, Juan V; Pitarch, Elena; Ibáñez, Maria; Hernández, Félix

2009-04-10

An ultra-high-pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method has been developed for the simultaneous quantification and confirmation of 11 basic/acidic illicit drugs and relevant metabolites in surface and urban wastewater at ng/L levels. The sample pre-treatment consisted of a solid-phase extraction using Oasis MCX cartridges. Analyte deuterated compounds were used as surrogate internal standards (except for norbenzoylecgonine and norcocaine) to compensate for possible errors resulting from matrix effects and those associated to the sample preparation procedure. After SPE enrichment, the selected drugs were separated within 6min under UHPLC optimized conditions. To efficiently combine UHPLC with MS/MS, a fast-acquisition triple quadrupole mass analyzer (TQD from Waters) in positive-ion mode (ESI+) was used. The excellent selectivity and sensitivity of the TQD analyzer in selected reaction monitoring mode allowed quantification and reliable identification at the LOQ levels. Satisfactory recoveries (70-120%) and precision (RSD<20%) were obtained for most compounds in different types of water samples, spiked at two concentration levels [limit of quantification (LOQ) and 10LOQ]. Thus, surface water was spiked at 30 ng/L and 300 ng/L (amphetamine and amphetamine-like stimulants), 10 ng/L and 100 ng/L (cocaine and its metabolites), 300 ng/L and 3000 ng/L (tetrahydrocannabinol-COOH). Recovery experiments in effluent and influent wastewater were performed at spiking levels of three and fifteen times higher than the levels spiked in surface water, respectively. The validated method was applied to urban wastewater samples (influent and effluent). The acquisition of three selected reaction monitoring transitions per analyte allowed positive findings to be confirmed by accomplishment of ion ratios between the quantification transition and two additional specific confirmation transitions. In general, drug consumption increased in the weekends and during an important musical event. The highest concentration levels were 27.5 microg/L and 10.5 microg/L, which corresponded to 3,4-methylenedioxymethamphetamine (MDMA, or ecstasy) and to benzoylecgonine (a cocaine metabolite), respectively. The wastewater treatment plants showed good removal efficiency (>99%) for low levels of illicit drugs in water, but some difficulties were observed when high drug levels were present in wastewaters.

A review of available analytical technologies for qualitative and quantitative determination of nitramines.

PubMed

Lindahl, Sofia; Gundersen, Cathrine Brecke; Lundanes, Elsa

2014-08-01

This review aims to summarize the available analytical methods in the open literature for the determination of some aliphatic and cyclic nitramines. Nitramines covered in this review are the ones that can be formed from the use of amines in post-combustion CO2 capture (PCC) plants and end up in the environment. Since the literature is quite scarce regarding the determination of nitramines in aqueous and soil samples, methods for determination of nitramines in other matrices have also been included. Since the nitramines are found in complex matrices and/or in very low concentration, an extraction step is often necessary before their determination. Liquid-liquid extraction (LLE) using dichloromethane and solid phase extraction (SPE) with an activated carbon based material have been the two most common extraction methods. Gas chromatography (GC) or reversed phase liquid chromatography (RPLC) has been used often combined with mass spectrometry (MS) in the final determination step. Presently there is no comprehensive method available that can be used for determination of all nitramines included in this review. The lowest concentration limit of quantification (cLOQ) is in the ng L(-1) range, however, most methods appear to have a cLOQ in the μg L(-1) range, if the cLOQ has been given.

Levels of lead in foods from the first French total diet study on infants and toddlers.

PubMed

Guérin, Thierry; Le Calvez, Emilie; Zinck, Julie; Bemrah, Nawel; Sirot, Véronique; Leblanc, Jean-Charles; Chekri, Rachida; Hulin, Marion; Noël, Laurent

2017-12-15

Infants and toddlers are highly vulnerable to exposure to lead due to its higher absorption in small children than in adults. This study describes the optimisation and validation of a very sensitive method for the determination of low levels of lead in foods mostly consumed by infants and toddlers. This method, based on inductively coupled plasma-mass spectrometry with a programmable temperature cyclonic spray chamber, attained a limit of quantification (LOQ) of 0.6 or 0.9µgPbkg -1 for a liquid or a solid sample, that was improved by a factor 5.6-8.3 compared to the previous method (LOQ: 5µgkg -1 ). The analytical method was then applied to 291 food samples from the first French total diet study on infants and toddlers. Lead was detected in most samples at relatively low concentrations (range 0.0-16µgkg -1 ). The highest lead concentrations were mainly found in processed food products (e.g. products containing chocolate). Copyright © 2017 Elsevier Ltd. All rights reserved.

Occurrence and removal of NDMA and NDMA formation potential in wastewater treatment plants.

PubMed

Yoon, Suchul; Nakada, Norihide; Tanaka, Hiroaki

2011-06-15

N-Nitrosodimethylamine (NDMA) is a potent carcinogen that is formed during disinfection by chlorination or ozonation in wastewater treatment plants (WWTPs). At present, little is known about the occurrence and fate of NDMA and its formation potential (FP) during wastewater treatment. We investigated the fate of NDMA and NDMA FP in 12 WWTPs. NDMA occurred in the influents at a concentration ranging from below the limit of quantification (LOQ <10 ng/L) to 80 ng/L, and in the final discharges from below the LOQ to 73 ng/L. In three WWTPs located in industrial areas, the influent had a high NDMA FP (up to 8230 ng/L). The rate of NDMA FP reduction from influent to secondary effluent varied between 85 and 98%, regardless of treatment process. The rate of NDMA removal is due more to the influent properties than to the type of biological treatment process. Copyright © 2011 Elsevier B.V. All rights reserved.

Highly sensitive and selective analysis of urinary steroids by comprehensive two-dimensional gas chromatography combined with positive chemical ionization quadrupole mass spectrometry

PubMed Central

Zhang, Ying; Tobias, Herbert J.; Brenna, J. Thomas

2014-01-01

Comprehensive two dimensional gas chromatography (GC×GC) provides greater separation space than conventional GC. Because of fast peak elution, a time of flight mass spectrometer (TOFMS) is the usual structure-specific detector of choice. The quantitative capabilities of a novel GC×GC fast quadrupole MS were investigated with electron ionization (EI), and CH4 or NH3 positive chemical ionization (PCI) for analysis of endogenous urinary steroids targeted in anti-doping tests. Average precisions for steroid quantitative analysis from replicate urine extractions were 6% (RSD) for EI and 8% for PCI-NH3. The average limits of detection (LOD) calculated by quantification ions for 12 target steroids spiked into steroid-free urine matrix (SFUM) were 2.6 ng mL−1 for EI, 1.3 ng mL−1 for PCI-CH4, and 0.3 ng mL−1 for PCI-NH3, all in mass scanning mode. The measured limits of quantification (LOQ) with full mass scan GC×GC-qMS were comparable with the LOQ values measured by one-dimensional GC-MS in single ion monitoring (SIM) mode. PCI-NH3 yields fewer fragments and greater (pseudo)molecular ion abundances than EI or PCI-CH4. These data show a benchtop GC×GC-qMS system has the sensitivity, specificity, and resolution to analyze urinary steroids at normal urine concentrations, and that PCI-NH3, not currently available on most GC×GC-TOFMS instruments, is of particular value for generation of structure-specific ions. PMID:22606686

Simultaneous determination of four aflatoxins and ochratoxin A in ginger after inoculation with fungi by ultra-fast liquid chromatography-tandem mass spectrometry.

PubMed

Yang, Ying; Wen, Jing; Kong, Weijun; Liu, Qiutao; Luo, Hongli; Wang, Jian; Yang, Meihua

2016-09-01

Aflatoxins (AFs) and ochratoxin A (OTA) have been detected frequently in food, agricultural products and traditional Chinese medicines, and their presence poses serious health and economic problems worldwide. Ginger can easily be polluted with mycotoxins. In this study, ginger samples were cultivated for 15 days after inoculation with fungi and were prepared based on ultrasound-assisted solid-liquid extraction using methanol/water followed by immunoaffinity column clean-up and analysed by ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) for AFs and OTA. The limits of detection and quantification of AFs and OTA were 0.04-0.30 µg mL(-1) and 0.125-1.0 µg mL(-1) , respectively. The recoveries were 82.0-100.2%. After 15 days' cultivation, no macroscopic mildew was found in ginger. But, the content of AFB1 expressed an increasing trend in ginger, peel [less than the limit of quantification (LOQ)] to the innermost layer (51.86 µ mL(-1) ), AFB2 was only detected in the innermost layer at the level of 0.87 µ mL(-1) . A small amount (

Quantification of Triacylglycerol Molecular Species in Edible Fats and Oils by Gas Chromatography-Flame Ionization Detector Using Correction Factors.

PubMed

Yoshinaga, Kazuaki; Obi, Junji; Nagai, Toshiharu; Iioka, Hiroyuki; Yoshida, Akihiko; Beppu, Fumiaki; Gotoh, Naohiro

2017-03-01

In the present study, the resolution parameters and correction factors (CFs) of triacylglycerol (TAG) standards were estimated by gas chromatography-flame ionization detector (GC-FID) to achieve the precise quantification of the TAG composition in edible fats and oils. Forty seven TAG standards comprising capric acid, lauric acid, myristic acid, pentadecanoic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, and/or linolenic acid were analyzed, and the CFs of these TAGs were obtained against tripentadecanoyl glycerol as the internal standard. The capillary column was Ultra ALLOY + -65 (30 m × 0.25 mm i.d., 0.10 μm thickness) and the column temperature was programmed to rise from 250°C to 360°C at 4°C/min and then hold for 25 min. The limit of detection (LOD) and limit of quantification (LOQ) values of the TAG standards were > 0.10 mg and > 0.32 mg per 100 mg fat and oil, respectively, except for LnLnLn, and the LOD and LOQ values of LnLnLn were 0.55 mg and 1.84 mg per 100 mg fat and oil, respectively. The CFs of TAG standards decreased with increasing total acyl carbon number and degree of desaturation of TAG molecules. Also, there were no remarkable differences in the CFs between TAG positional isomers such as 1-palmitoyl-2-oleoyl-3-stearoyl-rac-glycerol, 1-stearoyl-2-palmitoyl-3-oleoyl-rac-glycerol, and 1-palmitoyl-2-stearoyl-3-oleoyl-rac-glycerol, which cannot be separated by GC-FID. Furthermore, this method was able to predict the CFs of heterogeneous (AAB- and ABC-type) TAGs from the CFs of homogenous (AAA-, BBB-, and CCC-type) TAGs. In addition, the TAG composition in cocoa butter, palm oil, and canola oil was determined using CFs, and the results were found to be in good agreement with those reported in the literature. Therefore, the GC-FID method using CFs can be successfully used for the quantification of TAG molecular species in natural fats and oils.

Development and in-house validation of the event-specific qualitative and quantitative PCR detection methods for genetically modified cotton MON15985.

PubMed

Jiang, Lingxi; Yang, Litao; Rao, Jun; Guo, Jinchao; Wang, Shu; Liu, Jia; Lee, Seonghun; Zhang, Dabing

2010-02-01

To implement genetically modified organism (GMO) labeling regulations, an event-specific analysis method based on the junction sequence between exogenous integration and host genomic DNA has become the preferential approach for GMO identification and quantification. In this study, specific primers and TaqMan probes based on the revealed 5'-end junction sequence of GM cotton MON15985 were designed, and qualitative and quantitative polymerase chain reaction (PCR) assays were established employing the designed primers and probes. In the qualitative PCR assay, the limit of detection (LOD) was 0.5 g kg(-1) in 100 ng total cotton genomic DNA, corresponding to about 17 copies of haploid cotton genomic DNA, and the LOD and limit of quantification (LOQ) for quantitative PCR assay were 10 and 17 copies of haploid cotton genomic DNA, respectively. Furthermore, the developed quantitative PCR assays were validated in-house by five different researchers. Also, five practical samples with known GM contents were quantified using the developed PCR assay in in-house validation, and the bias between the true and quantification values ranged from 2.06% to 12.59%. This study shows that the developed qualitative and quantitative PCR methods are applicable for the identification and quantification of GM cotton MON15985 and its derivates.

Technical note: Simultaneous carotenoid and vitamin analysis of milk from total mixed ration-fed cows optimized for xanthophyll detection.

PubMed

Stout, M A; Benoist, D M; Drake, M A

2018-06-01

Concentrations of retinol, α-tocopherol, and major carotenoids in dairy products are often determined simultaneously by liquid chromatography. These compounds have different polarity and solubility; thus, extracting them simultaneously can be difficult and inefficient. In milks with low carotenoid concentrations, the xanthophylls lutein and zeaxanthin may not be completely resolved using common extraction techniques. A simplified method was developed to optimize extraction efficiency and the limit of detection and limit of quantification (LoQ) of lutein and zeaxanthin in bovine milk without decreasing sensitivity to other vitamins or carotenoids. The developed method evaluates lutein, zeaxanthin, β-carotene, retinol, and α-tocopherol simultaneously by ultra-high performance liquid chromatography-photodiode array detection. Common saponification temperatures (40-60°C) and concentrations of KOH in water (10-50% KOH wt/vol) were evaluated. Multiple solvents were evaluated for optimal xanthophyll extraction (diethyl ether, dichloromethane, hexane, and tetrahydrofuran) following saponification. The limit of detection and LoQ were defined as 3:1 and 10:1 signal-to-noise ratio, respectively. All experiments were performed in triplicate. The optimal saponification procedure was a concentration of 25% KOH at either 40 or 50°C. Saponified extracts solubilized in solutions containing diethyl ether had greater concentrations of lutein- than hexane- or tetrahydrofuran-based solutions, with peak areas above LoQ values. The solution containing diethyl ether solubilized similar concentrations of retinol, α-tocopherol, and β-carotene when compared with other solutions. The proposed optimized method allows for the simultaneous determination of carotenoids from milk with increased lutein and zeaxanthin sensitivity without sacrificing recovery of retinol, α-tocopherol, and β-carotene. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Development and validation of a gas chromatography/ion trap-mass spectrometry method for simultaneous quantification of cocaine and its metabolites benzoylecgonine and norcocaine: application to the study of cocaine metabolism in human primary cultured renal cells.

PubMed

Valente, Maria João; Carvalho, Félix; Bastos, M Lourdes; Carvalho, Márcia; de Pinho, Paula Guedes

2010-11-15

Acute renal failure is a common finding in cocaine abusers. While cocaine metabolism may contribute to its nephrotoxic mechanisms, its pharmacokinetics in kidney cells is hitherto to be clarified. Primary cultures of human proximal tubular cells (HPTCs) provide a well-characterized in vitro model, phenotypically representative of HPTCs in vivo. Thus, the present work describes the first sensitive gas chromatography/ion trap-mass spectrometry (GC/IT-MS) method for measurement of cocaine and its metabolites benzoylecgonine (BE) and norcocaine (NCOC) using a primary culture of HPTCs as cellular matrix, following solid phase extraction (SPE) and derivatization with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA). The application of this methodology also enables the identification of two other cocaine metabolites: ecgonine methyl ester (EME) and anhydroecgonine methyl ester (AEME). The validation of the method was performed through the evaluation of selectivity, linearity, precision and accuracy, limit of detection (LOD), and limit of quantification (LOQ). Its applicability was demonstrated through the quantification of cocaine, BE and NCOC in primary cultured HPTCs after incubation, at physiological conditions, with 1 mM cocaine for 72 h. The developed GC/IT-MS method was found to be linear (r² > 0.99). The intra-day precision varied between 3.6% and 13.5% and the values of accuracy between 92.7% and 111.9%. The LOD values for cocaine, BE and NCOC were 0.97±0.09, 0.40±0.04 and 20.89±1.81 ng/mL, respectively, and 3.24±0.30, 1.34±0.14 and 69.62±6.05 ng/mL as LOQ values. Copyright © 2010 Elsevier B.V. All rights reserved.

Development of an Advanced HPLC–MS/MS Method for the Determination of Carotenoids and Fat-Soluble Vitamins in Human Plasma

PubMed Central

Hrvolová, Barbora; Martínez-Huélamo, Miriam; Colmán-Martínez, Mariel; Hurtado-Barroso, Sara; Lamuela-Raventós, Rosa Maria; Kalina, Jiří

2016-01-01

The concentration of carotenoids and fat-soluble vitamins in human plasma may play a significant role in numerous chronic diseases such as age-related macular degeneration and some types of cancer. Although these compounds are of utmost interest for human health, methods for their simultaneous determination are scarce. A new high pressure liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS) method for the quantification of selected carotenoids and fat-soluble vitamins in human plasma was developed, validated, and then applied in a pilot dietary intervention study with healthy volunteers. In 50 min, 16 analytes were separated with an excellent resolution and suitable MS signal intensity. The proposed HPLC–MS/MS method led to improvements in the limits of detection (LOD) and quantification (LOQ) for all analyzed compounds compared to the most often used HPLC–DAD methods, in some cases being more than 100-fold lower. LOD values were between 0.001 and 0.422 µg/mL and LOQ values ranged from 0.003 to 1.406 µg/mL, according to the analyte. The accuracy, precision, and stability met with the acceptance criteria of the AOAC (Association of Official Analytical Chemists) International. According to these results, the described HPLC-MS/MS method is adequately sensitive, repeatable and suitable for the large-scale analysis of compounds in biological fluids. PMID:27754400

Development of an Advanced HPLC-MS/MS Method for the Determination of Carotenoids and Fat-Soluble Vitamins in Human Plasma.

PubMed

Hrvolová, Barbora; Martínez-Huélamo, Miriam; Colmán-Martínez, Mariel; Hurtado-Barroso, Sara; Lamuela-Raventós, Rosa Maria; Kalina, Jiří

2016-10-14

The concentration of carotenoids and fat-soluble vitamins in human plasma may play a significant role in numerous chronic diseases such as age-related macular degeneration and some types of cancer. Although these compounds are of utmost interest for human health, methods for their simultaneous determination are scarce. A new high pressure liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS) method for the quantification of selected carotenoids and fat-soluble vitamins in human plasma was developed, validated, and then applied in a pilot dietary intervention study with healthy volunteers. In 50 min, 16 analytes were separated with an excellent resolution and suitable MS signal intensity. The proposed HPLC-MS/MS method led to improvements in the limits of detection (LOD) and quantification (LOQ) for all analyzed compounds compared to the most often used HPLC-DAD methods, in some cases being more than 100-fold lower. LOD values were between 0.001 and 0.422 µg/mL and LOQ values ranged from 0.003 to 1.406 µg/mL, according to the analyte. The accuracy, precision, and stability met with the acceptance criteria of the AOAC (Association of Official Analytical Chemists) International. According to these results, the described HPLC-MS/MS method is adequately sensitive, repeatable and suitable for the large-scale analysis of compounds in biological fluids.

Simultaneous accelerated solvent extraction and hydrolysis of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid glucuronide in meconium samples for gas chromatography-mass spectrometry analysis.

PubMed

Mantovani, Cinthia de Carvalho; Silva, Jefferson Pereira E; Forster, Guilherme; Almeida, Rafael Menck de; Diniz, Edna Maria de Albuquerque; Yonamine, Mauricio

2018-02-01

Cannabis misuse during pregnancy is associated with severe impacts on the mother and baby health, such as newborn low birth weight, growth restriction, pre-term birth, neurobehavioral and developmental deficits. In most of the cases, drug abuse is omitted or denied by the mothers. Thus, toxicological analyzes using maternal-fetal matrices takes place as a suitable tool to assess drug use. Herein, meconium was the chosen matrix to evaluate cannabis exposure through identification and quantification of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic (THCCOOH). Accelerated solvent extraction (ASE) was applied for sample preparation technique to simultaneously extract and hydrolyze conjugated THCCOOH from meconium, followed by a solid-phase extraction (SPE) procedure. The method was developed and validated for gas chromatography-mass spectrometry (GC-MS), reaching hydrolysis efficiency of 98%. Limits of detection (LOD) and quantification (LOQ) were, respectively, 5 and 10 ng/g. The range of linearity was LOQ to 500 ng/g. Inter and intra-batch coefficients of variation were <8.4% for all concentration levels. Accuracy was in 101.7-108.9% range. Recovery was on average 60.3%. Carryover effect was not observed. The procedure was applied in six meconium samples from babies whose mothers were drug users and showed satisfactory performance to confirm fetal cannabis exposure. Copyright © 2018 Elsevier B.V. All rights reserved.

Validated enantiospecific LC method for determination of (R)-enantiomer impurity in (S)-efavirenz.

PubMed

Seshachalam, U; Narasimha Rao, D V L; Chandrasekhar, K B

2008-02-01

A high-performance liquid chromatographic method was developed for separation of the enantiomers of efavirenz. The developed method was applied for the determination of (R)-enantiomer in (S)-efavirenz and satisfactory results were achieved. The base line separation with a resolution of more than 4.0 was achieved on Chiralcel OD (250 mm x 4.6 mm, 10 microm) column containing tris-(3,5-dimethylphenylcarbomate) as stationary phase. The mobile phase consists of n-hexane: isopropyl alcohol (80:20 v/v) with 0.1% (v/v) of formic acid as additive. The flow rate was kept at 1.0 ml/min and the UV detection was monitored at 254 nm. The (R)-enantiomer was found linear over the range of 0.1 microg/ml--6 microg/ml. The limit of detection (LOD) was 0.03 microg/ml and the limit of quantification (LOQ) was 0.1 microg/ml (n=3. The precision of (R)-enantiomer at LOQ level was evaluated through six replicate injections and the RSD of the peak response was achieved as 1.34%. The results demonstrated that the developed LC method was simple, precise, robust and applicable for the purity determination of efavirenz.

High sensitivity mass spectrometric quantification of serum growth hormone by amphiphilic peptide conjugation

NASA Astrophysics Data System (ADS)

Arsene, Cristian G.; Schulze, Dirk; Kratzsch, Jürgen; Henrion, André

2012-12-01

Amphiphilic peptide conjugation affords a significant increase in sensitivity with protein quantification by electrospray-ionization mass spectrometry. This has been demonstrated here for human growth hormone in serum using N-(3-iodopropyl)-N,N,N-dimethyloctylammonium iodide (IPDOA-iodide) as derivatizing reagent. The signal enhancement achieved in comparison to the method without derivatization enables extension of the applicable concentration range down to the very low concentrations as encountered with clinical glucose suppression tests for patients with acromegaly. The method has been validated using a set of serum samples spiked with known amounts of recombinant 22 kDa growth hormone in the range of 0.48 to 7.65 \\mug/L. The coefficient of variation (CV) calculated, based on the deviation of results from the expected concentrations, was 3.5% and the limit of quantification (LoQ) was determined as 0.4 \\mug/L. The potential of the method as a tool in clinical practice has been demonstrated with patient samples of about 1 \\mug/L.

Establishment of a method for determination of arsenic species in seafood by LC-ICP-MS.

PubMed

Zmozinski, Ariane V; Llorente-Mirandes, Toni; López-Sánchez, José F; da Silva, Márcia M

2015-04-15

An analytical method for determination of arsenic species (inorganic arsenic (iAs), methylarsonic acid (MA), dimethylarsinic acid (DMA), arsenobetaine (AB), trimethylarsine oxide (TMAO) and arsenocholine (AC)) in Brazilian and Spanish seafood samples is reported. This study was focused on extraction and quantification of inorganic arsenic (iAs), the most toxic form. Arsenic speciation was carried out via LC with both anionic and cationic exchange with ICP-MS detection (LC-ICP-MS). The detection limits (LODs), quantification limits (LOQs), precision and accuracy for arsenic species were established. The proposed method was evaluated using eight reference materials (RMs). Arsenobetaine was the main species found in all samples. The total and iAs concentration in 22 seafood samples and RMs ranged between 0.27-35.2 and 0.02-0.71 mg As kg(-1), respectively. Recoveries ranging from 100% to 106% for iAs, based on spikes, were achieved. The proposed method provides reliable iAs data for future risk assessment analysis. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Immunoaffinity columns and determination of ochratoxin A in cereals by HPLC. Part I.: Evaluation of extraction using methanol/water].

PubMed

Czerwiecki, Ludwik; Czyzyk, Kamila; Kwiecień, Agnieszka; Wilczyńska, Grazyna

2004-01-01

The method for ochratoxin A determination in cereals (wheat, rye) was described. Application of immunoaffinity columns (IAC) for clean-up of extracts was investigated. The ochratoxin A content was determined by high-performance liquid chromatography using C18 column and fluorimetric detection at 330 nm (excitation) and 460 nm (emission). The mean recovery of ochratoxin A was 65-78%. The limits of detection (LOD) and quantification (LOQ) were 0.015 and 0.025 microg/kg, respectively. The positive results were confirmed by reaction with BF3 complex in methanol.

Rapid Detection of Melamine in Tap Water and Milk Using Conjugated "One-Step" Molecularly Imprinted Polymers-Surface Enhanced Raman Spectroscopic Sensor.

PubMed

Hu, Yaxi; Lu, Xiaonan

2016-05-01

An innovative "one-step" sensor conjugating molecularly imprinted polymers and surface enhanced Raman spectroscopic-active substrate (MIPs-SERS) was investigated for simultaneous extraction and determination of melamine in tap water and milk. This sensor was fabricated by integrating silver nanoparticles (AgNPs) with MIPs synthesized by bulk polymerization of melamine (template), methacrylic acid (functional monomer), ethylene glycol dimethacrylate (cross-linking agent), and 2,2'-azobisisobutyronitrile (initiator). Static and kinetic adsorption tests validated the specific affinity of MIPs-AgNPs to melamine and the rapid adsorption equilibration rate. Principal component analysis segregated SERS spectral features of tap water and milk samples with different melamine concentrations. Partial least squares regression models correlated melamine concentrations in tap water and skim milk with SERS spectral features. The limit of detection (LOD) and limit of quantification (LOQ) of melamine in tap water were determined as 0.0019 and 0.0064 mmol/L, while the LOD and LOQ were 0.0165 and 0.055 mmol/L for the determination of melamine in skim milk. However, this sensor is not ideal to quantify melamine in tap water and skim milk. By conjugating MIPs with SERS-active substrate (that is, AgNPs), reproducibility of SERS spectral features was increased, resulting in more accurate detection. The time required to determine melamine in tap water and milk were 6 and 25 min, respectively. The low LOD, LOQ, and rapid detection confirm the potential of applying this sensor for accurate and high-throughput detection of melamine in tap water and milk. © 2016 Institute of Food Technologists®

Simultaneous determination of macronutrients, micronutrients and trace elements in mineral fertilizers by inductively coupled plasma optical emission spectrometry

NASA Astrophysics Data System (ADS)

de Oliveira Souza, Sidnei; da Costa, Silvânio Silvério Lopes; Santos, Dayane Melo; dos Santos Pinto, Jéssica; Garcia, Carlos Alexandre Borges; Alves, José do Patrocínio Hora; Araujo, Rennan Geovanny Oliveira

2014-06-01

An analytical method for simultaneous determination of macronutrients (Ca, Mg, Na and P), micronutrients (Cu, Fe, Mn and Zn) and trace elements (Al, As, Cd, Pb and V) in mineral fertilizers was optimized. Two-level full factorial design was applied to evaluate the optimal proportions of reagents used in the sample digestion on hot plate. A Doehlert design for two variables was used to evaluate the operating conditions of the inductively coupled plasma optical emission spectrometer in order to accomplish the simultaneous determination of the analyte concentrations. The limits of quantification (LOQs) ranged from 2.0 mg kg- 1 for Mn to 77.3 mg kg- 1 for P. The accuracy and precision of the proposed method were evaluated by analysis of standard reference materials (SRMs) of Western phosphate rock (NIST 694), Florida phosphate rock (NIST 120C) and Trace elements in multi-nutrient fertilizer (NIST 695), considered to be adequate for simultaneous determination. Twenty-one samples of mineral fertilizers collected in Sergipe State, Brazil, were analyzed. For all samples, the As, Ca, Cd and Pb concentrations were below the LOQ values of the analytical method. For As, Cd and Pb the obtained LOQ values were below the maximum limit allowed by the Brazilian Ministry of Agriculture, Livestock and Food Supply (Ministério da Agricultura, Pecuária e Abastecimento - MAPA). The optimized method presented good accuracy and was effectively applied to quantitative simultaneous determination of the analytes in mineral fertilizers by inductively coupled plasma optical emission spectrometry (ICP OES).

Determination of Sphingosine-1-Phosphate in Human Plasma Using Liquid Chromatography Coupled with Q-Tof Mass Spectrometry

PubMed Central

Egom, Emmanuel E.; Fitzgerald, Ross; Canning, Rebecca; Pharithi, Rebabonye B.; Murphy, Colin; Maher, Vincent

2017-01-01

Evidence suggests that high-density lipoprotein (HDL) components distinct from cholesterol, such as sphingosine-1-phosphate (S1P), may account for the anti-atherothrombotic effects attributed to this lipoprotein. The current method for the determination of plasma levels of S1P as well as levels associated with HDL particles is still cumbersome an assay method to be worldwide practical. Recently, a simplified protocol based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the sensitive and specific quantification of plasma levels of S1P with good accuracy has been reported. This work utilized a triple quadrupole (QqQ)-based LC-MS/MS system. Here we adapt that method for the determination of plasma levels of S1P using a quadrupole time of flight (Q-Tof) based LC-MS system. Calibration curves were linear in the range of 0.05 to 2 µM. The lower limit of quantification (LOQ) was 0.05 µM. The concentration of S1P in human plasma was determined to be 1 ± 0.09 µM (n = 6). The average accuracy over the stated range of the method was found to be 100 ± 5.9% with precision at the LOQ better than 10% when predicting the calibration standards. The concentration of plasma S1P in the prepared samples was stable for 24 h at room temperature. We have demonstrated the quantification of plasma S1P using Q-Tof based LC-MS with very good sensitivity, accuracy, and precision that can used for future studies in this field. PMID:28820460

Non-linear mixed effects modeling of antiretroviral drug response after administration of lopinavir, atazanavir and efavirenz containing regimens to treatment-naïve HIV-1 infected patients.

PubMed

Röshammar, Daniel; Simonsson, Ulrika S H; Ekvall, Håkan; Flamholc, Leo; Ormaasen, Vidar; Vesterbacka, Jan; Wallmark, Eva; Ashton, Michael; Gisslén, Magnus

2011-12-01

The objective of this analysis was to compare three methods of handling HIV-RNA data below the limit of quantification (LOQ) when describing the time-course of antiretroviral drug response using a drug-disease model. Treatment naïve Scandinavian HIV-positive patients (n = 242) were randomized to one of three study arms. Two nucleoside reverse transcriptase inhibitors were administrated in combination with 400/100 mg lopinavir/ritonavir twice daily, 300/100 mg atazanavir/ritonavir once a day or 600 mg efavirenz once a day. The viral response was monitored at screening, baseline and at 1, 2, 3, 4, 12, 24, 48, 96, 120, and 144 weeks after study initiation. Data up to 400 days was fitted using a viral dynamics non-linear mixed effects drug-disease model in NONMEM. HIV-RNA data below LOQ of 50 copies/ml plasma (39%) was omitted, replaced by LOQ/2 or included in the analysis using a likelihood-based method (M3 method). Including data below LOQ using the M3 method substantially improved the model fit. The drug response parameter expressing the fractional inhibition of viral replication was on average (95% CI) estimated to 0.787 (0.721-0.864) for lopinavir and atazanavir treatment arms and 0.868 (0.796-0.923) for the efavirenz containing regimen. At 400 days after treatment initiation 90% (76-100) of the lopinavir and atazanavir treated patients were predicted to have undetectable viral levels and 96% (89-100%) for the efavirenz containing treatment. Including viral data below the LOQ rather than omitting or replacing data provides advantages such as better model predictions and less biased parameter estimates which are of importance when quantifying antiretroviral drug response.

Enantiomeric analysis of overlapped chromatographic profiles in the presence of interferences. Determination of ibuprofen in a pharmaceutical formulation containing homatropine.

PubMed

Padró, J M; Osorio-Grisales, J; Arancibia, J A; Olivieri, A C; Castells, C B

2016-10-07

In this work, we studied the combination of chemometric methods with chromatographic separations as a strategy applied to the analysis of enantiomers when complete enantioseparation is difficult or requires long analysis times and, in addition, the target signals have interference from the matrix. We present the determination of ibuprofen enantiomers in pharmaceutical formulations containing homatropine as interference by chiral HPLC-DAD detection in combination with partial least-squares algorithms. The method has been applied to samples containing enantiomeric ratios from 95:5 to 99.5:0.5 and coelution of interferents. The results were validated using univariate calibration and without homatropine. Relative error of the method was less than 4.0%, for both enantiomers. Limits of detection (LOD) and quantification (LOQ) for (S)-(+)-ibuprofen were 4.96×10 -10 and 1.50×10 -9 mol, respectively. LOD and LOQ for the R-(-)-ibuprofen were LOD=1.60×10 -11 mol and LOQ=4.85×10 -11 mol, respectively. Finally, the chemometric method was applied to the determination of enantiomeric purity of commercial pharmaceuticals. The ultimate goal of this research was the development of rapid, reliable, and robust methods for assessing enantiomeric purity by conventional diode array detector assisted by chemometric tools. Copyright © 2016 Elsevier B.V. All rights reserved.

Development and application of a multi-targeting reference plasmid as calibrator for analysis of five genetically modified soybean events.

PubMed

Pi, Liqun; Li, Xiang; Cao, Yiwei; Wang, Canhua; Pan, Liangwen; Yang, Litao

2015-04-01

Reference materials are important in accurate analysis of genetically modified organism (GMO) contents in food/feeds, and development of novel reference plasmid is a new trend in the research of GMO reference materials. Herein, we constructed a novel multi-targeting plasmid, pSOY, which contained seven event-specific sequences of five GM soybeans (MON89788-5', A2704-12-3', A5547-127-3', DP356043-5', DP305423-3', A2704-12-5', and A5547-127-5') and sequence of soybean endogenous reference gene Lectin. We evaluated the specificity, limit of detection and quantification, and applicability of pSOY in both qualitative and quantitative PCR analyses. The limit of detection (LOD) was as low as 20 copies in qualitative PCR, and the limit of quantification (LOQ) in quantitative PCR was 10 copies. In quantitative real-time PCR analysis, the PCR efficiencies of all event-specific and Lectin assays were higher than 90%, and the squared regression coefficients (R(2)) were more than 0.999. The quantification bias varied from 0.21% to 19.29%, and the relative standard deviations were from 1.08% to 9.84% in simulated samples analysis. All the results demonstrated that the developed multi-targeting plasmid, pSOY, was a credible substitute of matrix reference materials, and could be used as a reliable reference calibrator in the identification and quantification of multiple GM soybean events.

Ultrasensitive Single Fluorescence-Labeled Probe-Mediated Single Universal Primer-Multiplex-Droplet Digital Polymerase Chain Reaction for High-Throughput Genetically Modified Organism Screening.

PubMed

Niu, Chenqi; Xu, Yuancong; Zhang, Chao; Zhu, Pengyu; Huang, Kunlun; Luo, Yunbo; Xu, Wentao

2018-05-01

As genetically modified (GM) technology develops and genetically modified organisms (GMOs) become more available, GMOs face increasing regulations and pressure to adhere to strict labeling guidelines. A singleplex detection method cannot perform the high-throughput analysis necessary for optimal GMO detection. Combining the advantages of multiplex detection and droplet digital polymerase chain reaction (ddPCR), a single universal primer-multiplex-ddPCR (SUP-M-ddPCR) strategy was proposed for accurate broad-spectrum screening and quantification. The SUP increases efficiency of the primers in PCR and plays an important role in establishing a high-throughput, multiplex detection method. Emerging ddPCR technology has been used for accurate quantification of nucleic acid molecules without a standard curve. Using maize as a reference point, four heterologous sequences ( 35S, NOS, NPTII, and PAT) were selected to evaluate the feasibility and applicability of this strategy. Surprisingly, these four genes cover more than 93% of the transgenic maize lines and serve as preliminary screening sequences. All screening probes were labeled with FAM fluorescence, which allows the signals from the samples with GMO content and those without to be easily differentiated. This fiveplex screening method is a new development in GMO screening. Utilizing an optimal amplification assay, the specificity, limit of detection (LOD), and limit of quantitation (LOQ) were validated. The LOD and LOQ of this GMO screening method were 0.1% and 0.01%, respectively, with a relative standard deviation (RSD) < 25%. This method could serve as an important tool for the detection of GM maize from different processed, commercially available products. Further, this screening method could be applied to other fields that require reliable and sensitive detection of DNA targets.

Development and validation of a sensitive UPLC-MS/MS instrumentation and alkaline nitrobenzene oxidation method for the determination of lignin monomers in wheat straw.

PubMed

Zheng, Mengjing; Gu, Shubo; Chen, Jin; Luo, Yongli; Li, Wenqian; Ni, Jun; Li, Yong; Wang, Zhenlin

2017-06-15

A method to determine the lignin monomers (p-hydroxybenzaldehyde, vanillin and syringaldehyde) in plant cell wall of wheat internode was developed and validated using a high-throughput nitrobenzene oxidation step and ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for quantification. UPLC analyses were carried out using an reversed phase C 18 column (ACQUITY UPLC BEH, 1.7μm, 2.1×100mm) and gradient elution with water and acetonitrile. This method was completely validated in terms of analyzing speed, linearity, sensitivity, limits of detection (LODs) and limits of quantification (LOQs).The three lignin monomers were successfully separated within 6min and only 2min were required to regain its equilibrium. The method linearity with regression coefficients values (R2) greater than 0.997. Additionally, LODs ranged from 0.21 to 0.89μgL -1 and LOQs ranged from 0.69 to 2.95μgL -1 . The applicability of this analytical approach for determining the three lignin monomers was confirmed by the successful analysis of real samples of wheat stem internodes. The nitrobenzene oxidation method was used for the analysis of lignin monomers. We have optimized the treatment temperature (170°C, 1h) and realized the high-throughput using the microwave digestion instrument. Recovery of this extraction method ranged from 68.4% to 77.7%. The analysis result showed that the guaiacyl unit (G) was the major component of lignin and there was a higher content of the syringyl unit (S) than that of the hydroxybenzyl unit (H). Copyright © 2017. Published by Elsevier B.V.

Analytical and clinical performance of thyroglobulin autoantibody assays in thyroid cancer follow-up.

PubMed

Katrangi, Waddah; Grebe, Stephan K G; Algeciras-Schimnich, Alicia

2017-10-26

While thyroglobulin autoantibodies (TgAb) can result in false low serum thyroglobulin (Tg) immunoassay (IA) measurements, they might also be indicators of disease persistence/recurrence. Hence, accurate TgAb measurement, in addition to Tg quantification, is crucial for thyroid cancer monitoring. We compared the analytical and clinical performance of four commonly used TgAb IAs. We measured Tg by mass spectrometry (Tg-MS) and by four pairs of Tg and TgAb IAs (Beckman, Roche, Siemens, Thermo) in 576 samples. Limit of quantitation (LOQ) and manufacturers' upper reference interval cut-off (URI) were used for comparisons. Clinical performance was assessed by receiving operator characteristics (ROC) curve analysis. Quantitative and qualitative agreement between TgAb-IAs was moderate with R2 of 0.20-0.70 and κ from 0.41-0.66 using LOQ and 0.47-0.71 using URI. In samples with TgAb interference, detection rates of TgAb were similar using LOQ and URI for Beckman, Siemens, and Thermo, but much lower for the Roche TgAb-IA when the URI was used. In TgAb positive cases, the ROC areas under the curve (AUC) for the TgAb-IAs were 0.59 (Beckman), 0.62 (Siemens), 0.59 (Roche), and 0.59 (Thermo), similar to ROC AUCs achieved with Tg. Combining Tg and TgAb measurements improved the ROC AUCs compared to Tg or TgAb alone. TgAb-IAs show significant qualitative and quantitative differences. For 2 of the 4 TgAb-IAs, using the LOQ improves the detection of interfering TgAbs. All assays showed suboptimal clinical performance when used as surrogate markers of disease, with modest improvements when Tg and TgAb were combined.

Capillary electrophoresis with contactless conductivity detection for the quantification of fluoride in lithium ion battery electrolytes and in ionic liquids-A comparison to the results gained with a fluoride ion-selective electrode.

PubMed

Pyschik, Marcelina; Klein-Hitpaß, Marcel; Girod, Sabrina; Winter, Martin; Nowak, Sascha

2017-02-01

In this study, an optimized method using capillary electrophoresis (CE) with a direct contactless conductivity detector (C 4 D) for a new application field is presented for the quantification of fluoride in common used lithium ion battery (LIB) electrolyte using LiPF 6 in organic carbonate solvents and in ionic liquids (ILs) after contacted to Li metal. The method development for finding the right buffer and the suitable CE conditions for the quantification of fluoride was investigated. The results of the concentration of fluoride in different LIB electrolyte samples were compared to the results from the ion-selective electrode (ISE). The relative standard deviations (RSDs) and recovery rates for fluoride were obtained with a very high accuracy in both methods. The results of the fluoride concentration in the LIB electrolytes were in very good agreement for both methods. In addition, the limit of detection (LOD) and limit of quantification (LOQ) values were determined for the CE method. The CE method has been applied also for the quantification of fluoride in ILs. In the fresh IL sample, the concentration of fluoride was under the LOD. Another sample of the IL mixed with Li metal has been investigated as well. It was possible to quantify the fluoride concentration in this sample. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Novel Selective Deep Eutectic Solvent Extraction Method for Versatile Determination of Copper in Sediment Samples by ICP-OES.

PubMed

Bağda, Esra; Altundağ, Huseyin; Tüzen, Mustafa; Soylak, Mustafa

2017-08-01

In the present study, a simple, mono step deep eutectic solvent (DES) extraction was developed for selective extraction of copper from sediment samples. The optimization of all experimental parameters, e.g. DES type, sample/DES ratio, contact time and temperature were performed with using BCR-280 R (lake sediment certified reference material). The limit of detection (LOD) and the limit of quantification (LOQ) were found as 1.2 and 3.97 µg L -1 , respectively. The RSD of the procedure was 7.5%. The proposed extraction method was applied to river and lake sediments sampled from Serpincik, Çeltek, Kızılırmak (Fadl and Tecer region of the river), Sivas-Turkey.

Statistical characterization of multiple-reaction monitoring mass spectrometry (MRM-MS) assays for quantitative proteomics

PubMed Central

2012-01-01

Multiple reaction monitoring mass spectrometry (MRM-MS) with stable isotope dilution (SID) is increasingly becoming a widely accepted assay for the quantification of proteins and peptides. These assays have shown great promise in relatively high throughput verification of candidate biomarkers. While the use of MRM-MS assays is well established in the small molecule realm, their introduction and use in proteomics is relatively recent. As such, statistical and computational methods for the analysis of MRM-MS data from proteins and peptides are still being developed. Based on our extensive experience with analyzing a wide range of SID-MRM-MS data, we set forth a methodology for analysis that encompasses significant aspects ranging from data quality assessment, assay characterization including calibration curves, limits of detection (LOD) and quantification (LOQ), and measurement of intra- and interlaboratory precision. We draw upon publicly available seminal datasets to illustrate our methods and algorithms. PMID:23176545

Statistical characterization of multiple-reaction monitoring mass spectrometry (MRM-MS) assays for quantitative proteomics.

PubMed

Mani, D R; Abbatiello, Susan E; Carr, Steven A

2012-01-01

Multiple reaction monitoring mass spectrometry (MRM-MS) with stable isotope dilution (SID) is increasingly becoming a widely accepted assay for the quantification of proteins and peptides. These assays have shown great promise in relatively high throughput verification of candidate biomarkers. While the use of MRM-MS assays is well established in the small molecule realm, their introduction and use in proteomics is relatively recent. As such, statistical and computational methods for the analysis of MRM-MS data from proteins and peptides are still being developed. Based on our extensive experience with analyzing a wide range of SID-MRM-MS data, we set forth a methodology for analysis that encompasses significant aspects ranging from data quality assessment, assay characterization including calibration curves, limits of detection (LOD) and quantification (LOQ), and measurement of intra- and interlaboratory precision. We draw upon publicly available seminal datasets to illustrate our methods and algorithms.

Simultaneous liquid chromatography-tandem mass spectrometry analysis of brominated flame retardants (tetrabromobisphenol A and hexabromocyclododecane diastereoisomers) in French breast milk.

PubMed

Inthavong, Chanthadary; Hommet, Frédéric; Bordet, François; Rigourd, Virginie; Guérin, Thierry; Dragacci, Sylviane

2017-11-01

TBBPA and HBCDs are the two classes of flame retardants that are still allowed for use by the European Commission. In May 2013, HBCDs were listed as Persistent Organic Pollutants under the Stockholm Convention, and they were banned with an exemption on EPS/XPS for cavity wall insulation. This study describes the development and optimisation of a rapid LC-ESI-MS/MS method using isotopic dilution quantification including a simplified extraction step using a mixture of solvents and sulphuric acid hydrolysis followed by the one-shot analysis of TBBPA and each of the α-, β- and γ-HBCD diastereoisomers. The limits of detection and quantification (LOD and LOQ) were 0.5 and 2.5 ng g -1 (lipid weight, lw) for TBBPA and HBCD diastereoisomers, respectively. The method was applied to analyse 106 samples of individual mature breast milk. TBBPA was quantified in 42% of these samples within a range of

Simultaneous Liquid Chromatography–Mass Spectrometry Quantification of Urinary Opiates, Cocaine, and Metabolites in Opiate-Dependent Pregnant Women in Methadone-Maintenance Treatment

PubMed Central

Shakleya, Diaa M.; Dams, Riet; Choo, Robin E.; Jones, Hendree; Huestis, Marilyn A.

2011-01-01

Opiates, cocaine, and metabolites were quantified by liquid chromatography–mass spectrometry (LC–MS) in 284 urine specimens, collected thrice weekly, to monitor possible drug relapse in 15 pregnant heroin-dependent women. Opiates were detected in 149 urine specimens (52%) with limits of quantification (LOQ) of 10–50 μg/L. Morphine, morphine-3-glucuronide, and/or morphine-6-glucuronide were positive in 121 specimens; 6-acetylmorphine, a biomarker of heroin ingestion, was quantifiable in only 7. No heroin, 6-acetylcodeine, papaverine, or noscapine were detected. One hundred and sixty-five urine specimens (58%) from all 15 participants were positive for one or more cocaine analytes (LOQ 10–100 μg/L). Ecgonine methylester (EME) and/or benzoylecgonine were the major cocaine biomarkers in 142. Anhydroecgonine methylester, a biomarker of smoked cocaine, was positive in six; cocaethylene and/or ecgonine ethylester, biomarkers of cocaine and ethanol co-ingestion, were found in 25. At the current Substance Abuse Mental Health Services Administration cutoffs for total morphine (2000 μg/L), codeine (2000 μg/L), 6-acetylmorphine (10 μg/L), and benzoylecgonine (100 μg/L), 16 opiate- and 29 cocaine-positive specimens were identified. Considering 100 μg/L EME as an additional urinary cocaine biomarker would identify 51 more positive cocaine specimens. Of interest is the differential pattern of opiate and cocaine biomarkers observed after LC–MS as compared to gas chromatography–mass spectrometry analysis. PMID:20109298

Validation of a GC-MS method for the estimation of dithiocarbamate fungicide residues and safety evaluation of mancozeb in fruits and vegetables.

PubMed

Mujawar, Sumaiyya; Utture, Sagar C; Fonseca, Eddie; Matarrita, Jessie; Banerjee, Kaushik

2014-05-01

A sensitive and rugged residue analysis method was validated for the estimation of dithiocarbamate fungicides in a variety of fruit and vegetable matrices. The sample preparation method involved reaction of dithiocarbamates with Tin(II) chloride in aqueous HCl. The CS2 produced was absorbed into an isooctane layer and estimated by GC-MS selected ion monitoring. Limit of quantification (LOQ) was ⩽40μgkg(-1) for grape, green chilli, tomato, potato, brinjal, pineapple and chayote and the recoveries were within 75-104% (RSD<15% at LOQ). The method could be satisfactorily applied for analysis of real world samples. Dissipation of mancozeb, the most-used dithiocarbamate fungicide, in field followed first+first order kinetics with pre-harvest intervals of 2 and 4days in brinjal, 7 and 10days in grapes and 0day in chilli at single and double dose of agricultural applications. Cooking practices were effective for removal of mancozeb residues from vegetables. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development, Optimization, and Evaluation of a Duplex Droplet Digital PCR Assay To Quantify the T-nos/hmg Copy Number Ratio in Genetically Modified Maize.

PubMed

Félix-Urquídez, Dalmira; Pérez-Urquiza, Melina; Valdez Torres, José-Benigno; León-Félix, Josefina; García-Estrada, Raymundo; Acatzi-Silva, Abraham

2016-01-05

Certified reference materials (CRMs) are required to guarantee the reliability of analytical measurements. The CRMs available in the field of genetically modified organisms (GMOs) are characterized using real-time polymerase chain reaction (qPCR). This technology has limited application, because of its dependence on a calibrant. The objective of this study was to obtain a method with higher metrological quality, to characterize the CRMs for their contents of T-nos/hmg copy number ratio in maize. A duplex droplet digital PCR (ddPCR) assay was developed and optimized by a central composite design. The developed method achieved an absolute limit of detection (LOD) of 11 cP T-nos, a relative LOD of 0.034%, a limit of quantification (LOQ) of 23 cP (relative LOQ of 0.08%), and a dynamic range of 0.08%-100% T-nos/hmg ratio. The specificity and applicability of the assay were established for the analysis of low T-nos concentrations (0.9%) in several corn varieties. The convenience of DNA digestion to reduce measurement bias in the case of multiple-copy binding was confirmed through an enzymatic restriction assay. Given its overall performance, this method can be used to characterize CRM candidates for their contents of T-nos/hmg ratio.

Development, Optimization, and Evaluation of a Duplex Droplet Digital PCR Assay To Quantify the T-nos/hmg Copy Number Ratio in Genetically Modified Maize

PubMed Central

2015-01-01

Certified reference materials (CRMs) are required to guarantee the reliability of analytical measurements. The CRMs available in the field of genetically modified organisms (GMOs) are characterized using real-time polymerase chain reaction (qPCR). This technology has limited application, because of its dependence on a calibrant. The objective of this study was to obtain a method with higher metrological quality, to characterize the CRMs for their contents of T-nos/hmg copy number ratio in maize. A duplex droplet digital PCR (ddPCR) assay was developed and optimized by a central composite design. The developed method achieved an absolute limit of detection (LOD) of 11 cP T-nos, a relative LOD of 0.034%, a limit of quantification (LOQ) of 23 cP (relative LOQ of 0.08%), and a dynamic range of 0.08%–100% T-nos/hmg ratio. The specificity and applicability of the assay were established for the analysis of low T-nos concentrations (0.9%) in several corn varieties. The convenience of DNA digestion to reduce measurement bias in the case of multiple-copy binding was confirmed through an enzymatic restriction assay. Given its overall performance, this method can be used to characterize CRM candidates for their contents of T-nos/hmg ratio. PMID:26605751

Selective and sensitive fluorimetric determination of carbendazim in apple and orange after preconcentration with magnetite-molecularly imprinted polymer

NASA Astrophysics Data System (ADS)

İlktaç, Raif; Aksuner, Nur; Henden, Emur

2017-03-01

In this study, magnetite-molecularly imprinted polymer has been used for the first time as selective adsorbent before the fluorimetric determination of carbendazim. Adsorption capacity of the magnetite-molecularly imprinted polymer was found to be 2.31 ± 0.63 mg g- 1 (n = 3). Limit of detection (LOD) and limit of quantification (LOQ) of the method were found to be 2.3 and 7.8 μg L- 1, respectively. Calibration graph was linear in the range of 10-1000 μg L- 1. Rapidity is an important advantage of the method where re-binding and recovery processes of carbendazim can be completed within an hour. The same imprinted polymer can be used for the determination of carbendazim without any capacity loss repeatedly for at least ten times. Proposed method has been successfully applied to determine carbendazim residues in apple and orange, where the recoveries of the spiked samples were found to be in the range of 95.7-103%. Characterization of the adsorbent and the effects of some potential interferences were also evaluated. With the reasonably high capacity and reusability of the adsorbent, dynamic calibration range, rapidity, simplicity, cost-effectiveness and with suitable LOD and LOQ, the proposed method is an ideal method for the determination of carbendazim.

Variability of pesticide residues in cauliflower units collected from a field trial and market places in Greece.

PubMed

Prodhan, M D H; Papadakis, Emmanouil-N; Papadopoulou-Mourkidou, Euphemia

2016-09-01

To estimate the variability of pesticide residue levels present in cauliflower units, a total of 142 samples were collected from a field trial of a cooperative farmer, and 120 samples were collected from different market places in Thessaloniki, Greece. The collected samples were extracted using the quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction technique, and the residues were determined by liquid chromatography-tandem mass spectrometry. The developed method was validated by evaluating the accuracy, precision, linearity, limit of detection (LOD), and limit of quantification (LOQ). The average recoveries for all the analytes, derived from the data of control samples fortified at 0.01, 0.05, 0.1, and 0.2 mg/kg, ranged from 74 to 110% with a relative standard deviation of ≤8%. The correlation coefficient (R(2)) was ≥0.997 for all the analytes using matrix-matched calibration standards. The LOD values ranged from 0.001 to 0.003 mg/kg, and the LOQ was determined at 0.01 mg/kg for all the sought analytes. The matrix effect was found to be at a considerable level, especially for cypermethrin and deltamethrin, amounting to +90% and +145%, respectively. For the field samples, the unit-to-unit variability factors (VFs) calculated for cypermethrin and deltamethrin were 2.38 and 2.32, respectively, while the average VF for the market basket samples was 5.11. In the market basket samples, residues of cypermethrin, deltamethrin, chlorpyrifos, and indoxacarb were found at levels ≥LOQ and their respective VFs were 7.12, 5.67, 5.28, and 2.40.

Ultra-HPLC method for quality and adulterant assessment of steviol glycosides sweeteners - Stevia rebaudiana and stevia products.

PubMed

Wang, Yan-Hong; Avula, Bharathi; Tang, Wenzhao; Wang, Mei; Elsohly, Mahmoud A; Khan, Ikhlas A

2015-01-01

Stevia products are advertised as a zero-calorie sweetener. Glucose should not be an intrinsic component of this product, but it has been identified from some of stevia products in a preliminary study. An UHPLC-UV method was developed for the quantitative determination of glucose from stevia products. After stevia products reacted with 1-phenyl-3-methyl-5-pyrazolone (PMP), PMP derivatives were analysed and glucose was found in seven out of 35 products in the range 0.3-91.5% (w/w). Two products, SPR-12 and SPR-27, showed remarkable amounts of glucose at 61.6% and 91.5%, respectively. In addition, an UHPLC-UV-evaporative light-scattering detector (ELSD) method was developed for the quantitative determination of rebaudioside A, stevioside, rebaudioside D, dulcoside A and steviolbioside from Stevia rebaudiana and related products. In a 12 min run, five steviol glycosides were baseline-separated. ELSD and ultraviolet (UV) detections showed comparable results. The LC methods were validated for linearity, repeatability, accuracy, limits of detection (LOD) and limits of quantification (LOQ). For steviol glycosides, the LODs and LOQs were found to be less than 10 and 30 μg ml(-1), respectively. The RSD for intra- and inter-day analyses was less than 2.5%, and the recovery was 90-94%. For PMP derivative of glucose, the LOD and LOQ were 0.01 and 0.05 μg ml(-1), respectively. Repeatability (RSD) was less than 2.6%; recovery was 98.6-101.7%. The methods are useful for the identification, quality assurance, and adulterant assessment of S. rebaudiana and steviol glycosides sweeteners (stevia products).

Separation, isolation and stereochemical assignment of imazalil enantiomers and their quantitation in an in vitro toxicity test.

PubMed

Casas, Mònica Escolà; Kretschmann, Andreas Christopher; Andernach, Lars; Opatz, Till; Bester, Kai

2016-06-24

A simple method for the separation of the enantiomers of the fungicide imazalil was developed. Racemic imazalil was separated into its enantiomers with an enantiomeric purity of 99% using HPLC-UV with an enantioselective column (permethylated cyclodextrin) operated in reversed phase mode (water with 0.2% trimethylamine and 0.08% acetic acid and methanol). The absolute configuration of the separated enantiomers was assigned and unequivocally confirmed by optical rotation as well as by vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) combined with ab-initio calculations. The same enantioselective column was also used to develop an HPLC-MS/MS method for the quantification of imazalil enantiomers. The HPLC-MS/MS method reached limits of quantification (LOQs) of 0.025mg/mL with 5μL injections. This method was used to verify imazalil concentrations and enantiomeric fractions in samples from an in vitro test on effects on human steroidogenesis (H295R steroidogenesis assay). The quantification verified the stability of the enantiomers of imazalil during the in vitro tests. Copyright © 2016 Elsevier B.V. All rights reserved.

An ultra-high pressure liquid chromatography-tandem mass spectrometry method for the quantification of teicoplanin in plasma of neonates.

PubMed

Begou, O; Kontou, A; Raikos, N; Sarafidis, K; Roilides, E; Papadoyannis, I N; Gika, H G

2017-03-15

The development and validation of an ultra-high pressure liquid chromatography (UHPLC) tandem mass spectrometry (MS/MS) method was performed with the aim to be applied for the quantification of plasma teicoplanin concentrations in neonates. Pharmacokinetic data of teicoplanin in the neonatal population is very limited, therefore, a sensitive and reliable method for the determination of all isoforms of teicoplanin applied in a low volume of sample is of real importance. Teicoplanin main components were extracted by a simple acetonitrile precipitation step and analysed on a C18 chromatographic column by a triple quadrupole MS with electrospray ionization. The method provides quantitative data over a linear range of 25-6400ng/mL with LOD 8.5ng/mL and LOQ 25ng/mL for total teicoplanin. The method was applied in plasma samples from neonates to support pharmacokinetic data and proved to be a reliable and fast method for the quantification of teicoplanin concentration levels in plasma of infants during therapy in Intensive Care Unit. Copyright © 2016 Elsevier B.V. All rights reserved.

High-performance Thin-layer Chromatography Method Development, Validation, and Simultaneous Quantification of Four Compounds Identified in Standardized Extracts of Orthosiphon stamineus.

PubMed

Hashim, Suzana; Beh, Hooi Kheng; Hamil, Mohamad Shahrul Ridzuan; Ismail, Zhari; Majid, Amin Malik Shah Abdul

2016-01-01

Orthosiphon stamineus is a medicinal herb widely grown in Southeast Asia and tropical countries. It has been used traditionally as a diuretic, abdominal pain, kidney and bladder inflammation, gout, and hypertension. This study aims to develop and validate the high-performance thin layer chromatography (HPTLC) method for quantification of rosmarinic acid (RA), 3'-hydroxy-5,6,7,4'-tetramethoxyflavone (TMF), sinensitin (SIN) and eupatorin (EUP) found in ethanol, 50% ethanol and water extract of O. stamineus leaves. HPTLC method was conducted using an HPTLC system with a developed mobile phase system of toluene: ethyl acetate: formic acid (3:7:0.1) performed on precoated silica gel 60 F254 TLC plates. The method was validated based on linearity, accuracy, precision, limit of detection, limit of quantification (LOQ), and specificity, respectively. The detection of spots was observed at ultraviolet 254 nm and 366 nm. The linearity of RA, TMF, SIN, and EUP were obtained between 10 and 100 ng/spot with high correlation coefficient value (R 2 ) of more than 0.986. The limit of detection was found to be 122.47 ± 3.95 (RA), 43.38 ± 0.79 (SIN), 17.26 ± 1.16 (TMF), and 46.80 ± 1.33 ng/spot (EUP), respectively. Whereas the LOQ was found to be 376.44 ± 6.70 (RA), 131.45 ± 2.39 (SIN), 52.30 ± 2.01 (TMF), and 141.82 ± 1.58 ng/spot (EUP), respectively. The proposed method showed good linearity, precision, accuracy, and high sensitivity. Hence, it may be applied in a routine quantification of RA, SIN, TMF, and EUP found in ethanol, 50% of ethanol and water extract of O. stamineus leaves. HPTLC method provides rapid estimation of the marker compound for routine quality control analysis.The established HPTLC method is rapid for qualitative and quantitative fingerprinting of Orthosiphon stamineus extract used for commercial product.Four identified markers (RA, SIN, EUP and TMF) found in three a different type of O. stamineus extracts specifically ethanol, 50% ethanol and water extract were successfully quantified using HPTLC method. Abbreviations Used : HPTLC: High-performance thin layer chromatography; RA: Rosmarinic acid; TMF: 3'-hydroxy-5,6,7,4'-tetramethoxyflavone; SIN: Sinensitin; EUP: Eupatorin; E: Ethanol; EW: 50% ethanol; W: Water; BK: Batu Kurau; KB: Kepala Batas; S: Sik; CJ: Changkat Jering; SB: Sungai Buloh.

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

PubMed

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

2012-07-01

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

Ultra-high-performance liquid chromatography-tandem mass spectrometry measurement of climbazole deposition from hair care products onto artificial skin and human scalp.

PubMed

Chen, Guoqiang; Hoptroff, Michael; Fei, Xiaoqing; Su, Ya; Janssen, Hans-Gerd

2013-11-22

A sensitive and specific ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the measurement of climbazole deposition from hair care products onto artificial skin and human scalp. Deuterated climbazole was used as the internal standard. Atmospheric pressure chemical ionization (APCI) in positive mode was applied for the detection of climbazole. For quantification, multiple reaction monitoring (MRM) transition 293.0>69.0 was monitored for climbazole, and MRM transition 296.0>225.1 for the deuterated climbazole. The linear range ran from 4 to 2000 ng mL(-1). The limit of detection (LOD) and the limit of quantification (LOQ) were 1 ng mL(-1) and 4 ng mL(-1), respectively, which enabled quantification of climbazole on artificial skin and human scalp at ppb level (corresponding to 16 ng cm(-2)). For the sampling of climbazole from human scalp the buffer scrub method using a surfactant-modified phosphate buffered saline (PBS) solution was selected based on a performance comparison of tape stripping, the buffer scrub method and solvent extraction in in vitro studies. Using this method, climbazole deposition in in vitro and in vivo studies was successfully quantified. Copyright © 2013 Elsevier B.V. All rights reserved.

A new validated analytical method for the determination of tributyltin in water samples at the quantification level set by the European Union.

PubMed

Devos, Christophe; David, Frank; Sandra, Pat

2012-10-26

According to recent directives of the European Union (EU), limits of quantification (LOQ) for the determination of tributyltin (TBT) in surface waters should be ca. 60 pg/L (ppq). This put very stringent requirements on analytical methodologies; definitely when they have to be applied in a routine environment. Stir bar sorptive extraction (SBSE), followed by thermal desorption (TD) and capillary gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) can provide accurate and precise data at the 2 ng/L level (ppt). For lower concentrations, matrix and reagent interferences together with contamination may provide too high TBT values. A two-dimensional heart-cut GC method was developed to fractionate TBT from interferences. The GC-GC-MS/MS method shows excellent linearity in the range 50 pg/L-4 ng/L, good repeatability (RSD<20% at 200 pg/L), and a limit of detection of 11 pg/L. The method performance is demonstrated with representative samples i.e. harbor water and waste water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Identification, characterization, synthesis and HPLC quantification of new process-related impurities and degradation products in retigabine.

PubMed

Douša, Michal; Srbek, Jan; Rádl, Stanislav; Cerný, Josef; Klecán, Ondřej; Havlíček, Jaroslav; Tkadlecová, Marcela; Pekárek, Tomáš; Gibala, Petr; Nováková, Lucie

2014-06-01

Two new impurities were described and determined using gradient HPLC method with UV detection in retigabine (RET). Using LC-HRMS, NMR and IR analysis the impurities were identified as RET-dimer I: diethyl {4,4'-diamino-6,6'-bis[(4-fluorobenzyl)amino]biphenyl-3,3'-diyl}biscarbamate and RET-dimer II: ethyl {2-amino-5-[{2-amino-4-[(4-fluorobenzyl) amino] phenyl} (ethoxycarbonyl) amino]-4-[(4-fluorobenzyl)amino] phenyl}carbamate. Reference standards of these impurities were synthesized followed by semipreparative HPLC purification. The mechanism of the formation of these impurities is also discussed. An HPLC method was optimized in order to separate, selectively detect and quantify all process-related impurities and degradation products of RET. The presented method, which was validated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ) and selectivity is very quick (less than 11min including re-equilibration time) and therefore highly suitable for routine analysis of RET related substances as well as stability studies. Copyright © 2014 Elsevier B.V. All rights reserved.

Enzymatic digestion and selective quantification of underivatised delta-9-tetrahydrocannabinol and cocaine in human hair using gas chromatography-mass spectrometry.

PubMed

Breidi, Salah Eddine; Barker, James; Petróczi, Andrea; Naughton, Declan P

2012-01-01

Gas chromatography-mass spectrometric (GC-MS) methods for drug analysis routinely employ derivatising reagents. The aim of this paper was to develop a method for the analysis of two recreational drugs, delta-9-tetrahydrocannabinol (Δ(9)-THC) and cocaine in hair samples using GC-MS, without prior derivatisation, thus allowing the sample to be reanalysed in its original form. An enzymatic digestion technique was also developed. Ten hair samples, that were known positive for either Δ(9)-THC and/or cocaine, were enzymatically digested, extracted, and then analysed by GC-MS. All samples measured contained Δ(9)-THC and one sample contained cocaine. The limits of detection (LOD) and quantification (LOQ) were 0.02 ng/mg and 0.05 ng/mg, respectively, for cocaine and 0.015 ng/mg and 0.02 ng/mg, respectively, for Δ(9)-THC. The wide detection window, ease of direct analysis by GC-MS, lower detection limits of underivatised samples, and the stability of drugs using this technique may offer an improved method of analysis.

Enzymatic Digestion and Selective Quantification of Underivatised Delta-9-Tetrahydrocannabinol and Cocaine in Human Hair Using Gas Chromatography-Mass Spectrometry

PubMed Central

Breidi, Salah Eddine; Barker, James; Petróczi, Andrea; Naughton, Declan P.

2012-01-01

Gas chromatography-mass spectrometric (GC-MS) methods for drug analysis routinely employ derivatising reagents. The aim of this paper was to develop a method for the analysis of two recreational drugs, delta-9-tetrahydrocannabinol (Δ9-THC) and cocaine in hair samples using GC-MS, without prior derivatisation, thus allowing the sample to be reanalysed in its original form. An enzymatic digestion technique was also developed. Ten hair samples, that were known positive for either Δ9-THC and/or cocaine, were enzymatically digested, extracted, and then analysed by GC-MS. All samples measured contained Δ9-THC and one sample contained cocaine. The limits of detection (LOD) and quantification (LOQ) were 0.02 ng/mg and 0.05 ng/mg, respectively, for cocaine and 0.015 ng/mg and 0.02 ng/mg, respectively, for Δ9-THC. The wide detection window, ease of direct analysis by GC-MS, lower detection limits of underivatised samples, and the stability of drugs using this technique may offer an improved method of analysis. PMID:22567573

Quantitative analysis of substituted N,N-dimethyl-tryptamines in the presence of natural type XII alkaloids.

PubMed

Ivanova, Bojidarka; Spiteller, Michael

2012-10-01

This paper reports the qualitative and quantitative analysis (QA) of mixtures of hallucinogens, N,N-dimethyltryptamine (DMT) (1), 5-methoxy- (la) and 5-hydroxy-N,N-dimethyltryptamine (1b) in the presence of beta-carbolines (indole alkaloids of type XII) ((2), (3) and (5)}. The validated electronic absorption spectroscopic (EAs) protocol achieved a concentration limit of detection (LOD) of 7.2.10(-7) mol/L {concentration limit of quantification (LOQ) of 24.10(-7) mol/L) using bands (lambda max within 260+/-0.23-262+/-0.33 nm. Metrology, including accuracy, measurement repeatability, measurement precision, trueness of measurement, and reproducibility of the measurements are presented using N,N-dimethyltryptamine (DMA) as standard. The analytical quantities of mixtures of alkaloids 4, 6 and 7 are: lambda max 317+/-0.45, 338+/-0.69 and 430+/-0.09 for 4 (LOD, 8.6.10(-7) mol/L; LOQ, 28.66(6), mol/L), as well as 528+/-0.75 nm for 6 and 7 (LOD, 8.2.10(-7) mol/L; LOQ, 27.33(3), mol/L), respectively. The partially validated protocols by high performance liquid chromatography (HPLC), electrospray ionization (ESI), mass spectrometry (MS), both in single and tandem operation (MS/MS) mode, as well as matrix/assisted laser desorption/ionization (MALDI) MS are elaborated. The Raman spectroscopic (RS) protocol for analysis of psychoactive substances, characterized by strong fluorescence RS profile was developed, with the detection limits being discussed. The known synergistic effect leading to increase the psychoactive and hallucinogenic properties and the reported acute poisoning cases from 1-7, make the present study emergent, since as well the current lack of analytical data and the herein metrology obtained contributed to the elaboration of highly selective and precise analytical protocols, which would be of interest in the field of criminal forensic analysis.

The determination of levofloxacin by flow injection analysis using UV detection, potentiometry, and conductometry in pharmaceutical preparations.

PubMed

Altiokka, G; Atkosar, Z; Can, N O

2002-10-15

A flow injection analysis (FIA) using UV detection, potentiometry and conductometry for levofloxacin (LVF) are described in this study. The best solvent system was found to consist of 0.2 M acetate buffer at pH 3 having 10% MeOH. A flow rate of 1 ml min(-1) was pumped and active material was detected at 288 nm. The detection limit (LOD) and limit of quantification (LOQ) for FIA were calculated to be 3 x 10(-7) M (S/N = 3) and 1 x 10(-7) M (S/N = 10), respectively. In the analysis of tablets, the RSD values were found to be 0.83, 0.98 and 0.99 for FIA, potentiometric and conductometric methods, respectively. Copyright 2002 Elsevier Science B.V.

Powder X-ray diffraction method for the quantification of cocrystals in the crystallization mixture.

PubMed

Padrela, Luis; de Azevedo, Edmundo Gomes; Velaga, Sitaram P

2012-08-01

The solid state purity of cocrystals critically affects their performance. Thus, it is important to accurately quantify the purity of cocrystals in the final crystallization product. The aim of this study was to develop a powder X-ray diffraction (PXRD) quantification method for investigating the purity of cocrystals. The method developed was employed to study the formation of indomethacin-saccharin (IND-SAC) cocrystals by mechanochemical methods. Pure IND-SAC cocrystals were geometrically mixed with 1:1 w/w mixture of indomethacin/saccharin in various proportions. An accurately measured amount (550 mg) of the mixture was used for the PXRD measurements. The most intense, non-overlapping, characteristic diffraction peak of IND-SAC was used to construct the calibration curve in the range 0-100% (w/w). This calibration model was validated and used to monitor the formation of IND-SAC cocrystals by liquid-assisted grinding (LAG). The IND-SAC cocrystal calibration curve showed excellent linearity (R(2) = 0.9996) over the entire concentration range, displaying limit of detection (LOD) and limit of quantification (LOQ) values of 1.23% (w/w) and 3.74% (w/w), respectively. Validation results showed excellent correlations between actual and predicted concentrations of IND-SAC cocrystals (R(2) = 0.9981). The accuracy and reliability of the PXRD quantification method depend on the methods of sample preparation and handling. The crystallinity of the IND-SAC cocrystals was higher when larger amounts of methanol were used in the LAG method. The PXRD quantification method is suitable and reliable for verifying the purity of cocrystals in the final crystallization product.

Determination of 255 pesticides in edible vegetable oils using QuEChERS method and gas chromatography tandem mass spectrometry.

PubMed

He, Zeying; Wang, Yuehua; Wang, Lu; Peng, Yi; Wang, Wenwen; Liu, Xiaowei

2017-02-01

In this study, a simple and high-throughput method for determination of 255 pesticides in vegetable oils was developed based on QuEChERS sample preparation method combined with gas chromatography-triple quadrupole mass spectrometry. Different clean-up approaches were tested: A, 150 mg PSA + 150 mg C18; B, 250 mg PSA + 250 mg C18; C, 250 mg PSA + 250 mg C18 + 15 mg GCB; D, 250 mg PSA + 250 mg C18 + 50 mg GCB; and E, EMR-Lipid TM . Best clean-up capacity was observed for EMR clean-up. The extraction procedures and parameters, including extraction time, solvent/sample ratio, and buffer system, were also thoroughly investigated and optimized. The limits of quantification (LOQ) ranged between 5 and 50 μg kg -1 , and for the majority of the pesticides the LOQs were 5 μg kg -1 , which were below the regulatory MRLs. Most recoveries at seven spiking levels were in the range of 70-120 % with RSDs <20 % indicating satisfactory accuracy. The coefficient of determination (r 2 ) was >0.99 within the calibration linearity range of 2-500 μg L -1 for the majority of the pesticides. This method was proved to be simple, sensitive, and effective, which can be applied for large-scale pesticide screening and quantification in vegetable oils.

Accurate determination of 3-alkyl-2-methoxypyrazines in wines by gas chromatography quadrupole time-of-flight tandem mass spectrometry following solid-phase extraction and dispersive liquid-liquid microextraction.

PubMed

Fontana, Ariel; Rodríguez, Isaac; Cela, Rafael

2017-09-15

A new reliable method for the determination 3-alkyl-2-methoxypyrazines (MPs) in wine samples based on the sequential combination of solid-phase extraction (SPE), dispersive liquid-liquid microextraction (DLLME) and gas chromatography (GC) quadrupole time-of-flight accurate tandem mass spectrometry (QTOF-MS/MS) is presented. Primary extraction of target analytes was carried out by using a reversed-phase Oasis HLB (200mg) SPE cartridge combined with acetonitrile as elution solvent. Afterwards, the SPE extract was submitted to DLLME concentration using 0.06mL carbon tetrachloride (CCl 4 ) as extractant. Under final working conditions, sample concentration factors above 379 times and limits of quantification (LOQs) between 0.3 and 2.1ngL -1 were achieved. Moreover, the overall extraction efficiency of the method was unaffected by the particular characteristics of each wine; thus, accurate results (relative recoveries from 84 to 108% for samples spiked at concentrations from 5 to 25ngL -1 ) were obtained using matrix-matched standards, without using standard additions over every sample. Highly selective chromatographic records were achieved considering a mass window of 5mDa, centered in the quantification product ion corresponding to each compound. Twelve commercial wines, elaborated with grapes from different varieties and geographical origins, were processed with the optimized method. The 2-isobutyl-3-methoxypyrazine (IBMP) was determined at levels above the LOQs of the method in half of the samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Survey of aflatoxins in maize tortillas from Mexico City.

PubMed

Castillo-Urueta, Pável; Carvajal, Magda; Méndez, Ignacio; Meza, Florencia; Gálvez, Amanda

2011-01-01

In Mexico, maize tortillas are consumed on a daily basis, leading to possible aflatoxin exposure. In a survey of 396 2-kg samples, taken over four sampling days in 2006 and 2007 from tortilla shops and supermarkets in Mexico City, aflatoxin levels were quantified by HPLC. In Mexico, the regulatory limit is 12 µg kg⁻¹ total aflatoxins for maize tortillas. In this survey, 17% of tortillas contained aflatoxins at levels of 3-385 µg kg⁻¹ or values below the limit of quantification (12 µg kg⁻¹ and 87% were below the regulatory limit. Average aflatoxin concentrations in 56 contaminated samples were: AFB1 (12.1 µg kg⁻¹); AFB2 (2.7 µg kg⁻¹); AFG1 (64.1 µg kg⁻¹) and AFG2 (3.7 µg kg⁻¹), and total AF (20.3 µg kg⁻¹).

Estimation of the quantification uncertainty from flow injection and liquid chromatography transient signals in inductively coupled plasma mass spectrometry

NASA Astrophysics Data System (ADS)

Laborda, Francisco; Medrano, Jesús; Castillo, Juan R.

2004-06-01

The quality of the quantitative results obtained from transient signals in high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICPMS) and flow injection-inductively coupled plasma mass spectrometry (FI-ICPMS) was investigated under multielement conditions. Quantification methods were based on multiple-point calibration by simple and weighted linear regression, and double-point calibration (measurement of the baseline and one standard). An uncertainty model, which includes the main sources of uncertainty from FI-ICPMS and HPLC-ICPMS (signal measurement, sample flow rate and injection volume), was developed to estimate peak area uncertainties and statistical weights used in weighted linear regression. The behaviour of the ICPMS instrument was characterized in order to be considered in the model, concluding that the instrument works as a concentration detector when it is used to monitorize transient signals from flow injection or chromatographic separations. Proper quantification by the three calibration methods was achieved when compared to reference materials, although the double-point calibration allowed to obtain results of the same quality as the multiple-point calibration, shortening the calibration time. Relative expanded uncertainties ranged from 10-20% for concentrations around the LOQ to 5% for concentrations higher than 100 times the LOQ.

Simultaneous quantification of Δ9-tetrahydrocannabinol, 11-hydroxy-Δ9-tetrahydrocannabinol, and 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in human plasma using two-dimensional gas chromatography, cryofocusing, and electron impact-mass spectrometry

PubMed Central

Lowe, Ross H.; Karschner, Erin L.; Schwilke, Eugene W.; Barnes, Allan J.; Huestis, Marilyn A.

2009-01-01

A two-dimensional (2D) gas chromatography/electron impact-mass spectrometry (GC/EI-MS) method for simultaneous quantification of Δ9-tetrahydrocannabinol (THC), 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC), and 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH) in human plasma was developed and validated. The method employs 2D capillary GC and cryofocusing for enhanced resolution and sensitivity. THC, 11-OH-THC, and THCCOOH were extracted by precipitation with acetonitrile followed by solid-phase extraction. GC separation of trimethylsilyl derivatives of analytes was accomplished with two capillary columns in series coupled via a pneumatic Deans switch system. Detection and quantification were accomplished with a bench-top single quadrupole mass spectrometer operated in electron impact-selected ion monitoring mode. Limits of quantification (LOQ) were 0.125, 0.25 and 0.125 ng/mL for THC, 11-OH-THC, and THCCOOH, respectively. Accuracy ranged from 86.0 to 113.0% for all analytes. Intra- and inter-assay precision, as percent relative standard deviation, was less than 14.1% for THC, 11-OH-THC, and THCCOOH. The method was successfully applied to quantification of THC and its 11-OH-THC and THCCOOH metabolites in plasma specimens following controlled administration of THC. PMID:17640656

High-throughput quantification for a drug mixture in rat plasma-a comparison of Ultra Performance liquid chromatography/tandem mass spectrometry with high-performance liquid chromatography/tandem mass spectrometry.

PubMed

Yu, Kate; Little, David; Plumb, Rob; Smith, Brian

2006-01-01

A quantitative Ultra Performance liquid chromatography/tandem mass spectrometry (UPL/MS/MS) protocol was developed for a five-compound mixture in rat plasma. A similar high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) quantification protocol was developed for comparison purposes. Among the five test compounds, three preferred positive electrospray ionization (ESI) and two preferred negative ESI. As a result, both UPLC/MS/MS and HPLC/MS/MS analyses were performed by having the mass spectrometer collecting ESI multiple reaction monitoring (MRM) data in both positive and negative ion modes during a single injection. Peak widths for most standards were 4.8 s for the HPLC analysis and 2.4 s for the UPLC analysis. There were 17 to 20 data points obtained for each of the LC peaks. Compared with the HPLC/MS/MS method, the UPLC/MS/MS method offered 3-fold decrease in retention time, up to 10-fold increase in detected peak height, with 2-fold decrease in peak width. Limits of quantification (LOQs) for both HPLC and UPLC methods were evaluated. For UPLC/MS/MS analysis, a linear range up to four orders of magnitude was obtained with r2 values ranging from 0.991 to 0.998. The LOQs for the five analytes ranged from 0.08 to 9.85 ng/mL. Three levels of quality control (QC) samples were analyzed. For the UPLC/MS/MS protocol, the percent relative standard deviation (RSD%) for low QC (2 ng/mL) ranged from 3.42 to 8.67% (N = 18). The carryover of the UPLC/MS/MS protocol was negligible and the robustness of the UPLC/MS/MS system was evaluated with up to 963 QC injections. Copyright 2006 John Wiley & Sons, Ltd.

Simple, miniaturized blood plasma extraction method.

PubMed

Kim, Jin-Hee; Woenker, Timothy; Adamec, Jiri; Regnier, Fred E

2013-12-03

A rapid plasma extraction technology that collects a 2.5 μL aliquot of plasma within three minutes from a finger-stick derived drop of blood was evaluated. The utility of the plasma extraction cards used was that a paper collection disc bearing plasma was produced that could be air-dried in fifteen minutes and placed in a mailing envelop for transport to an analytical laboratory. This circumvents the need for venipuncture and blood collection in specialized vials by a phlebotomist along with centrifugation and refrigerated storage. Plasma extraction was achieved by applying a blood drop to a membrane stack through which plasma was drawn by capillary action. During the course of plasma migration to a collection disc at the bottom of the membrane stack blood cells were removed by a combination of adsorption and filtration. After the collection disc filled with an aliquot of plasma the upper membranes were stripped from the collection card and the collection disc was air-dried. Intercard differences in the volume of plasma collected varied approximately 1% while volume variations of less than 2% were seen with hematocrit levels ranging from 20% to 71%. Dried samples bearing metabolites and proteins were then extracted from the disc and analyzed. 25-Hydroxy vitamin D was quantified by LC-MS/MS analysis following derivatization with a secosteroid signal enhancing tag that imparted a permanent positive charge to the vitamin and reduced the limit of quantification (LOQ) to 1 pg of collected vitamin on the disc; comparable to values observed with liquid-liquid extraction (LLE) of a venipuncture sample. A similar study using conventional proteomics methods and spectral counting for quantification was conducted with yeast enolase added to serum as an internal standard. The LOQ with extracted serum samples for enolase was 1 μM, linear from 1 to 40 μM, the highest concentration examined. In all respects protein quantification with extracted serum samples was comparable to that observed with serum samples obtained by venipuncture.

A reversed-phase capillary ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) method for comprehensive top-down/bottom-up lipid profiling

PubMed Central

Gao, Xiaoli; Zhang, Qibin; Meng, Da; Issac, Giorgis; Zhao, Rui; Fillmore, Thomas L.; Chu, Rosey K.; Zhou, Jianying; Tang, Keqi; Hu, Zeping; Moore, Ronald J.; Smith, Richard D.; Katze, Michael G.; Metz, Thomas O.

2012-01-01

Lipidomics is a critical part of metabolomics and aims to study all the lipids within a living system. We present here the development and evaluation of a sensitive capillary UPLC-MS method for comprehensive top-down/bottom-up lipid profiling. Three different stationary phases were evaluated in terms of peak capacity, linearity, reproducibility, and limit of quantification (LOQ) using a mixture of lipid standards representative of the lipidome. The relative standard deviations of the retention times and peak abundances of the lipid standards were 0.29% and 7.7%, respectively, when using the optimized method. The linearity was acceptable at >0.99 over 3 orders of magnitude, and the LOQs were sub-fmol. To demonstrate the performance of the method in the analysis of complex samples, we analyzed lipids extracted from a human cell line, rat plasma, and a model human skin tissue, identifying 446, 444, and 370 unique lipids, respectively. Overall, the method provided either higher coverage of the lipidome, greater measurement sensitivity, or both, when compared to other approaches of global, untargeted lipid profiling based on chromatography coupled with MS. PMID:22354571

Improved coupled-column liquid chromatographic method for the determination of glyphosate and aminomethylphosphonic acid residues in environmental waters.

PubMed

Hidalgo, Carmén; Rios, Carolina; Hidalgo, Manuela; Salvadó, Victòria; Sancho, Juan V; Hernández, Félix

2004-04-30

An existing method for the determination of glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) in water has been improved. It is based on precolumn derivatization with the fluorescent reagent 9-fluorenylmethylcloroformate (FMOC) followed by large-volume injection in a coupled-column LC system using fluorescence detection (LC-LC-FD). The derivatization step was slightly modified by changing parameters such as volume and/or concentration of sample and reagents to decrease the limits of quantification (LOQ) of glyphosate and AMPA to 0.1 microg/l. Additionally, the use of Amberlite IRA-900 for preconcentration of glyphosate, prior to the derivatization step, was investigated; the LOQ of glyphosate was lowered to 0.02 microg/l. Drinking, surface and ground water spiked with glyphosate and AMPA at 0.1-10 microg/l concentrations were analysed by the improved LC-LC-FD method. Recoveries were 87-106% with relative standard deviations lower than 8%. Drinking and ground water spiked with glyphosate at 0.02 and 0.1 microg/l were analysed after preconcentration on the anion-exchange resin with satisfactory recoveries (94-105%) and precision (better than 8%).

Quantification of the IgG2/4 kappa Monoclonal Therapeutic Eculizumab from Serum Using Isotype Specific Affinity Purification and Microflow LC-ESI-Q-TOF Mass Spectrometry.

PubMed

Ladwig, Paula M; Barnidge, David R; Willrich, Maria A V

2017-05-01

As therapeutic monoclonal antibodies (mAbs) become more humanized, traditional tryptic peptide approaches used to measure biologics in serum become more challenging since unique clonotypic peptides used for quantifying the mAb may also be found in the normal serum polyclonal background. An alternative approach is to monitor the unique molecular mass of the intact light chain portion of the mAbs using liquid chromatography-mass spectrometry (LC-MS). Distinguishing a therapeutic mAb from a patient's normal polyclonal immunoglobulin (Ig) repertoire is the primary limiting factor when determining the limit of quantitation (LOQ) in serum. The ability to selectively extract subclass specific Igs from serum reduces the polyclonal background in a sample. We present here the development of an LC-MS method to quantify eculizumab in serum. Eculizumab is a complement component 5 (C5) binding mAb that is fully humanized and contains portions of both IgG2 and IgG4 subclasses. Our group developed a method that uses Life Technologies CaptureSelect IgG4 (Hu) affinity matrix. We show here the ability to quantitate eculizumab with a LOQ of 5 mcg/mL by removing the higher abundance IgG1, IgG2, and IgG3 from the polyclonal background, making this approach a simple and efficient procedure. Graphical Abstract ᅟ.

Multimycotoxin LC-MS/MS Analysis in Tea Beverages after Dispersive Liquid-Liquid Microextraction (DLLME).

PubMed

Pallarés, Noelia; Font, Guillermina; Mañes, Jordi; Ferrer, Emilia

2017-11-29

The aim of the present study was to develop a multimycotoxin liquid chromatography tandem mass spectrometry (LC-MS/MS) method with a dispersive liquid-liquid microextraction procedure (DLLME) for the analysis of AFs, 3aDON, 15aDON, NIV, HT-2, T-2, ZEA, OTA, ENNs, and BEA in tea beverages and to evaluate their mycotoxin contents. The proposed method was characterized in terms of linearity, limits of detection (LODs), limits of quantification (LOQs), recoveries, repeatability (intraday precision), reproducibility (interday precision), and matrix effects to check suitability. The results show LODs in the range of 0.05-10 μg/L, LOQs in the range of 0.2-33 μg/L, and recoveries in the range of 65-127% (RSD < 20%). The method developed in this study was applied to 44 commercial samples of black tea, red tea, green tea, and green mint tea. The results show that, of the analyzed mycotoxins, AFB2, AFG2, 15aDON, AFG1, and ENB were detected in the samples. AFB2 (14.4-32.2 μg/L) and 15aDON (60.5-61 μg/L) presented the highest levels. Green mint tea contained the highest concentration of mycotoxins. The risk assessment study shows that the population is not much exposed to mycotoxins through the consumption of tea beverages.

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.

Quantitative detection of bovine and porcine gelatin difference using surface plasmon resonance based biosensor

NASA Astrophysics Data System (ADS)

Wardani, Devy P.; Arifin, Muhammad; Suharyadi, Edi; Abraha, Kamsul

2015-05-01

Gelatin is a biopolymer derived from collagen that is widely used in food and pharmaceutical products. Due to some religion restrictions and health issues regarding the gelatin consumption which is extracted from certain species, it is necessary to establish a robust, reliable, sensitive and simple quantitative method to detect gelatin from different parent collagen species. To the best of our knowledge, there has not been a gelatin differentiation method based on optical sensor that could detect gelatin from different species quantitatively. Surface plasmon resonance (SPR) based biosensor is known to be a sensitive, simple and label free optical method for detecting biomaterials that is able to do quantitative detection. Therefore, we have utilized SPR-based biosensor to detect the differentiation between bovine and porcine gelatin in various concentration, from 0% to 10% (w/w). Here, we report the ability of SPR-based biosensor to detect difference between both gelatins, its sensitivity toward the gelatin concentration change, its reliability and limit of detection (LOD) and limit of quantification (LOQ) of the sensor. The sensor's LOD and LOQ towards bovine gelatin concentration are 0.38% and 1.26% (w/w), while towards porcine gelatin concentration are 0.66% and 2.20% (w/w), respectively. The results show that SPR-based biosensor is a promising tool for detecting gelatin from different raw materials quantitatively.

Quantification of the IgG2/4 kappa Monoclonal Therapeutic Eculizumab from Serum Using Isotype Specific Affinity Purification and Microflow LC-ESI-Q-TOF Mass Spectrometry

NASA Astrophysics Data System (ADS)

Ladwig, Paula M.; Barnidge, David R.; Willrich, Maria A. V.

2017-05-01

As therapeutic monoclonal antibodies (mAbs) become more humanized, traditional tryptic peptide approaches used to measure biologics in serum become more challenging since unique clonotypic peptides used for quantifying the mAb may also be found in the normal serum polyclonal background. An alternative approach is to monitor the unique molecular mass of the intact light chain portion of the mAbs using liquid chromatography-mass spectrometry (LC-MS). Distinguishing a therapeutic mAb from a patient's normal polyclonal immunoglobulin (Ig) repertoire is the primary limiting factor when determining the limit of quantitation (LOQ) in serum. The ability to selectively extract subclass specific Igs from serum reduces the polyclonal background in a sample. We present here the development of an LC-MS method to quantify eculizumab in serum. Eculizumab is a complement component 5 (C5) binding mAb that is fully humanized and contains portions of both IgG2 and IgG4 subclasses. Our group developed a method that uses Life Technologies CaptureSelect IgG4 (Hu) affinity matrix. We show here the ability to quantitate eculizumab with a LOQ of 5 mcg/mL by removing the higher abundance IgG1, IgG2, and IgG3 from the polyclonal background, making this approach a simple and efficient procedure.

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

PubMed

Wang, Jian-Hua; Guo, Cui

2010-07-09

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

Stability considerations of aspartame in the direct analysis of artificial sweeteners in water samples using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).

PubMed

Berset, Jean-Daniel; Ochsenbein, Nicole

2012-07-01

A HPLC-MS/MS method is presented for the simultaneous determination of frequently used artificial sweeteners (ASs) and the main metabolite of aspartame (ASP), diketopiperazine (DKP), in environmental water samples using the direct-injection (DI) technique, thereby achieving limits of quantification (LOQ) of 10 ng L(-1). For a reliable quantification of ASP pH should be adjusted to 4.3 to prevent formation of the metabolite. Acesulfame (ACE), saccharin (SAC), cyclamate (CYC) and sucralose (SUC) were ubiquitously found in water samples. Highest concentrations up to 61 μg L(-1) of ACE were found in wastewater effluents, followed by surface water with concentrations up to 7 μg L(-1), lakes up to 600 ng L(-1) and groundwater and tap water up to 70 ng L(-1). The metabolite DKP was only detected in wastewater up to 200 ng L(-1) and at low detection frequencies. Copyright © 2012 Elsevier Ltd. All rights reserved.

Simple and clean determination of tetracyclines by flow injection analysis

NASA Astrophysics Data System (ADS)

Rodríguez, Michael Pérez; Pezza, Helena Redigolo; Pezza, Leonardo

2016-01-01

An environmentally reliable analytical methodology was developed for direct quantification of tetracycline (TC) and oxytetracycline (OTC) using continuous flow injection analysis with spectrophotometric detection. The method is based on the diazo coupling reaction between the tetracyclines and diazotized sulfanilic acid in a basic medium, resulting in the formation of an intense orange azo compound that presents maximum absorption at 434 nm. Experimental design was used to optimize the analytical conditions. The proposed technique was validated over the concentration range of 1 to 40 μg mL- 1, and was successfully applied to samples of commercial veterinary pharmaceuticals. The detection (LOD) and quantification (LOQ) limits were 0.40 and 1.35 μg mL- 1, respectively. The samples were also analyzed by an HPLC method, and the results showed agreement with the proposed technique. The new flow injection method can be immediately used for quality control purposes in the pharmaceutical industry, facilitating monitoring in real time during the production processes of tetracycline formulations for veterinary use.

PCR technology for screening and quantification of genetically modified organisms (GMOs).

PubMed

Holst-Jensen, Arne; Rønning, Sissel B; Løvseth, Astrid; Berdal, Knut G

2003-04-01

Although PCR technology has obvious limitations, the potentially high degree of sensitivity and specificity explains why it has been the first choice of most analytical laboratories interested in detection of genetically modified (GM) organisms (GMOs) and derived materials. Because the products that laboratories receive for analysis are often processed and refined, the quality and quantity of target analyte (e.g. protein or DNA) frequently challenges the sensitivity of any detection method. Among the currently available methods, PCR methods are generally accepted as the most sensitive and reliable methods for detection of GM-derived material in routine applications. The choice of target sequence motif is the single most important factor controlling the specificity of the PCR method. The target sequence is normally a part of the modified gene construct, for example a promoter, a terminator, a gene, or a junction between two of these elements. However, the elements may originate from wildtype organisms, they may be present in more than one GMO, and their copy number may also vary from one GMO to another. They may even be combined in a similar way in more than one GMO. Thus, the choice of method should fit the purpose. Recent developments include event-specific methods, particularly useful for identification and quantification of GM content. Thresholds for labelling are now in place in many countries including those in the European Union. The success of the labelling schemes is dependent upon the efficiency with which GM-derived material can be detected. We will present an overview of currently available PCR methods for screening and quantification of GM-derived DNA, and discuss their applicability and limitations. In addition, we will discuss some of the major challenges related to determination of the limits of detection (LOD) and quantification (LOQ), and to validation of methods.

Spectrophotometric and chromatographic determination of insensitive energetic materials: HNS and NTO, in the presence of sensitive nitro-explosives.

PubMed

Can, Ziya; Uzer, Ayşem; Tekdemir, Yasemin; Erçağ, Erol; Türker, Lemi; Apak, Reşat

2012-02-15

As there are no molecular spectroscopic determination methods for the most widely used insensitive energetic materials, 2,2',4,4',6,6'-hexanitrostilbene (HNS) and 3-nitro-1,2,4-triazole-5-one (NTO), in the presence of sensitive nitro-explosives, two novel spectrophotometric methods were developed. For HNS and TNT mixtures, both analytes react with dicyclohexylamine (DCHA) forming different colored charge-transfer complexes, which can be resolved by derivative spectroscopy. The spectrophotometric method for NTO measures the 416-nm absorbance of its yellow-colored Na(+)NTO(-) salt formed with NaOH. TNT, if present, is pre-extracted into IBMK as its Meisenheimer anion forming an ion-pair with the cationic surfactant cetyl pyridinium (CP(+)) in alkaline medium, whereas the unextracted NTO is determined in the aqueous phase. The molar absorptivity (ε, L mol(-1)cm(-1)) and limit of quantification (LOQ, mg L(-1)) are as follows: for HNS, ε=2.75 × 10(4) and LOQ=0.48 (in admixture with TNT); for NTO, ε=6.83 × 10(3) and LOQ=0.73. These methods were not affected from nitramines and nitrate esters in synthetic mixtures or composite explosives. The developed methods were statistically validated against HPLC, and the existing chromatographic method was modified so as to enable NTO determination in the presence of TNT. These simple, low-cost, and versatile methods can be used in criminology, remediation/monitoring of contaminated sites, and kinetic stability modeling of munitions containing desensitized energetic materials. Copyright © 2012 Elsevier B.V. All rights reserved.

Pollution gets personal! A first population-based human biomonitoring study in Austria.

PubMed

Hohenblum, Philipp; Steinbichl, Philipp; Raffesberg, Wolfgang; Weiss, Stefan; Moche, Wolfgang; Vallant, Birgit; Scharf, Sigrid; Haluza, Daniela; Moshammer, Hanns; Kundi, Michael; Piegler, Brigitte; Wallner, Peter; Hutter, Hans-Peter

2012-02-01

Humans are exposed to a broad variety of man-made chemicals. Human biomonitoring (HBM) data reveal the individual body burden irrespective of sources and routes of uptake. A first population-based study was started in Austria in 2008 and was finished at the end of May 2011. This cross sectional study aims at documenting the extent, the distribution and the determinants of human exposure to industrial chemicals as well as proving the feasibility of a representative HBM study. Overall, 150 volunteers (50 families) were selected by stratified random sampling. Exposure to phthalates, trisphosphates, polybrominated diphenyl ethers (PBDE), bisphenol A (along with nonyl- and octyl phenol) and methyl mercury was assessed. Sixteen of 18 PBDE determined were detected above the limit of quantification (LOQ) in blood samples with #153 and #197 the most abundant species. Bisphenol A in urine was measured in a subsample of 25 with only 4 samples found above the LOQ. In 3 of 100 urine samples at least one of 8 trisphosphate compounds assessed was above the LOQ. These first analytical results of the human biomonitoring data show that the body burden of the Austrian population with respect to the assessed compounds is comparable to or even lower than in other European countries. Overall, the study revealed that in order to develop a feasible protocol for representative human biomonitoring studies procedures have to be optimized to allow for non-invasive sampling of body tissues in accordance with the main metabolic pathways. Procedures of participants' recruitment were, however, labor intensive and have to be improved. Copyright © 2011 Elsevier GmbH. All rights reserved.

A reliable and rapid tool for plasma quantification of 18 psychotropic drugs by ESI tandem mass spectrometry.

PubMed

Vecchione, Gennaro; Casetta, Bruno; Chiapparino, Antonella; Bertolino, Alessandro; Tomaiuolo, Michela; Cappucci, Filomena; Gatta, Raffaella; Margaglione, Maurizio; Grandone, Elvira

2012-01-01

A simple liquid chromatographic tandem mass spectrometry (LC-MS/MS) method has been developed for simultaneous analysis of 17 basic and one acid psychotropic drugs in human plasma. The method relies on a protein precipitation step for sample preparation and offers high sensitivity, wide linearity without interferences from endogenous matrix components. Chromatography was run on a reversed-phase column with an acetonitrile-H₂O mixture. The quantification of target compounds was performed in multiple reaction monitoring (MRM) and by switching the ionization polarity within the analytical run. A further sensitivity increase was obtained by implementing the functionality "scheduled multiple reaction monitoring" (sMRM) offered by the recent version of the software package managing the instrument. The overall injection interval was less than 5.5 min. Regression coefficients of the calibration curves and limits of quantification (LOQ) showed a good coverage of over-therapeutic, therapeutic and sub-therapeutic ranges. Recovery rates, measured as percentage of recovery of spiked plasma samples, were ≥ 94%. Precision and accuracy data have been satisfactory for a therapeutic drug monitoring (TDM) service as for managing plasma samples from patients receiving psycho-pharmacological treatment. Copyright © 2012 Elsevier B.V. All rights reserved.

A simple HPLC-DAD method for simultaneous detection of two organophosphates, profenofos and fenthion, and validation by soil microcosm experiment.

PubMed

Mahajan, Rishi; Chatterjee, Subhankar

2018-05-05

Indiscriminate use of two broad spectrum pesticides, profenofos and fenthion, in agricultural system, often results in their accumulation in a non-target niche and leaching into water bodies. The present study, therefore, aims at developing a simple and rapid HPLC method that allows simultaneous extraction and detection of these two pesticides, especially in run-off water. Extraction of the two pesticides from spiked water samples using dichloromethane resulted in recovery ranging between 80 and 90%. An HPLC run of 20 min under optimized chromatographic parameters (mobile phase: methanol (75%) and water (25%); flow rate of 0.8 ml min -1 ; diode array detector at wavelength 210 nm) resulted in a significant difference in retention times of two pesticides (4.593 min) which allows a window of opportunity to study any possible intermediates/transformants of the parent compounds while evaluating run-off waters from agricultural fields. The HPLC method developed allowed simultaneous detection of profenofos and fenthion with a single injection into the HPLC system with 0.0328 mg l -1 (32.83 ng ml -1 ) being the limit of detection (LOD) and 0.0995 mg l -1 (99.5 ng ml -1 ) as the limit of quantification (LOQ) for fenthion; for profenofos, LOD and LOQ were 0.104 mg l -1 (104.50 ng ml -1 ) and 0.316 mg l -1 (316.65 ng ml -1 ), respectively. The findings were further validated using the soil microcosm experiment that allowed simultaneous detection and quantification of profenofos and fenthion. The findings indicate towards the practical significance of the methodology developed as the soil microcosm experiment closely mimics the agricultural run-off water under natural environmental conditions.

Development and practical application of accelerated solvent extraction for the isolation of cocaine/crack biomarkers in meconium samples.

PubMed

Mantovani, Cínthia de Carvalho; Lima, Marcela Bittar; Oliveira, Carolina Dizioli Rodrigues de; Menck, Rafael de Almeida; Diniz, Edna Maria de Albuquerque; Yonamine, Mauricio

2014-04-15

A method using accelerated solvent extraction (ASE) for the isolation of cocaine/crack biomarkers in meconium samples, followed by solid phase extraction (SPE) and the simultaneous quantification by gas chromatography-mass spectrometry (GC-MS) was developed and validated. Initially, meconium samples were submitted to an ASE procedure, which was followed by SPE with Bond Elut Certify I cartridges. The analytes were derivatizated with PFP/PFPA and analyzed by GC-MS. The limits of detection (LOD) were between 11 and 17ng/g for all analytes. The limits of quantification (LOQ) were 30ng/g for anhydroecgonine methyl ester, and 20ng/g for cocaine, benzoylecgonine, ecgonine methyl ester and cocaethylene. Linearity ranged from the LOQ to 1500ng/g for all analytes, with a coefficients of determination greater than 0.991, except for m-hydroxybenzoylecgonine, which was only qualitatively detected. Precision and accuracy were evaluated at three concentration levels. For all analytes, inter-assay precision ranged from 3.2 to 18.1%, and intra-assay precision did not exceed 12.7%. The accuracy results were between 84.5 and 114.2% and the average recovery ranged from 17 to 84%. The method was applied to 342 meconium samples randomly collected in the University Hospital-University of São Paulo (HU-USP), Brazil. Cocaine biomarkers were detected in 19 samples, which represent 5.6% of exposure prevalence. Significantly lower birth weight, length and head circumference were found for the exposed newborns compared with the non-exposed group. This is the first report in which ASE was used as a sample preparation technique to extract cocaine biomarkers from a complex biological matrix such as meconium samples. The advantages of the developed method are the smaller demand for organic solvents and the minor sample handling, which allows a faster and accurate procedure, appropriate to confirm fetal exposure to cocaine/crack. Copyright © 2014 Elsevier B.V. All rights reserved.

A rapid and accurate quantification method for real-time dynamic analysis of cellular lipids during microalgal fermentation processes in Chlorella protothecoides with low field nuclear magnetic resonance.

PubMed

Wang, Tao; Liu, Tingting; Wang, Zejian; Tian, Xiwei; Yang, Yi; Guo, Meijin; Chu, Ju; Zhuang, Yingping

2016-05-01

The rapid and real-time lipid determination can provide valuable information on process regulation and optimization in the algal lipid mass production. In this study, a rapid, accurate and precise quantification method of in vivo cellular lipids of Chlorella protothecoides using low field nuclear magnetic resonance (LF-NMR) was newly developed. LF-NMR was extremely sensitive to the algal lipids with the limits of the detection (LOD) of 0.0026g and 0.32g/L in dry lipid samples and algal broth, respectively, as well as limits of quantification (LOQ) of 0.0093g and 1.18g/L. Moreover, the LF-NMR signal was specifically proportional to the cellular lipids of C. protothecoides, thus the superior regression curves existing in a wide detection range from 0.02 to 0.42g for dry lipids and from 1.12 to 8.97gL(-1) of lipid concentration for in vivo lipid quantification were obtained with all R(2) higher than 0.99, irrespective of the lipid content and fatty acids profile variations. The accuracy of this novel method was further verified to be reliable by comparing lipid quantification results to those obtained by GC-MS. And the relative standard deviation (RSD) of LF-NMR results were smaller than 2%, suggesting the precision of this method. Finally, this method was successfully used in the on-line lipid monitoring during the algal lipid fermentation processes, making it possible for better understanding of the lipid accumulation mechanism and dynamic bioprocess control. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of a gas chromatography method for azelaic acid determination in selected biological samples

PubMed Central

Garelnabi, Mahdi; Litvinov, Dmitry; Parthasarathy, Sampath

2010-01-01

Background: Azelaic acid (AzA) is the best known dicarboxilic acid to have pharmaceutical benefits and clinical applications and also to be associated with some diseases pathophysiology. Materials and Methods: We extracted and methylesterified AzA and determined its concentration in human plasma obtained from healthy individuals and also in mice fed AzA containing diet for three months. Results: AzA was detected in Gas Chromatography (GC) and confirmed by Liquid chromatography mass spectrometry (LCMS), and gas chromatography mass spectrometry (GCMC). Our results have shown that AzA can be determined efficiently in selected biological samples by GC method with 1nM limit of detection (LoD) and the limit of quantification (LoQ); was established at 50nM. Analytical Sensitivity as assayed by hexane demonstrated an analytical sensitivity at 0.050nM. The method has demonstrated 8-10% CV batch repeatability across the sample types and 13-18.9% CV for the Within-Lab Precision analysis. The method has shown that AzA can efficiently be recovered from various sample preparation including liver tissue homogenate (95%) and human plasma (97%). Conclusions: Because of its simplicity and lower limit of quantification, the present method provides a useful tool for determining AzA in various biological sample preparations. PMID:22558586

Evaluation of a gas chromatography method for azelaic acid determination in selected biological samples.

PubMed

Garelnabi, Mahdi; Litvinov, Dmitry; Parthasarathy, Sampath

2010-09-01

Azelaic acid (AzA) is the best known dicarboxilic acid to have pharmaceutical benefits and clinical applications and also to be associated with some diseases pathophysiology. We extracted and methylesterified AzA and determined its concentration in human plasma obtained from healthy individuals and also in mice fed AzA containing diet for three months. AzA was detected in Gas Chromatography (GC) and confirmed by Liquid chromatography mass spectrometry (LCMS), and gas chromatography mass spectrometry (GCMC). Our results have shown that AzA can be determined efficiently in selected biological samples by GC method with 1nM limit of detection (LoD) and the limit of quantification (LoQ); was established at 50nM. Analytical Sensitivity as assayed by hexane demonstrated an analytical sensitivity at 0.050nM. The method has demonstrated 8-10% CV batch repeatability across the sample types and 13-18.9% CV for the Within-Lab Precision analysis. The method has shown that AzA can efficiently be recovered from various sample preparation including liver tissue homogenate (95%) and human plasma (97%). Because of its simplicity and lower limit of quantification, the present method provides a useful tool for determining AzA in various biological sample preparations.

Development and validation of a method for mercury determination in seawater for the process control of a candidate certified reference material.

PubMed

Sánchez, Raquel; Snell, James; Held, Andrea; Emons, Hendrik

2015-08-01

A simple, robust and reliable method for mercury determination in seawater matrices based on the combination of cold vapour generation and inductively coupled plasma mass spectrometry (CV-ICP-MS) and its complete in-house validation are described. The method validation covers parameters such as linearity, limit of detection (LOD), limit of quantification (LOQ), trueness, repeatability, intermediate precision and robustness. A calibration curve covering the whole working range was achieved with coefficients of determination typically higher than 0.9992. The repeatability of the method (RSDrep) was 0.5 %, and the intermediate precision was 2.3 % at the target mass fraction of 20 ng/kg. Moreover, the method was robust with respect to the salinity of the seawater. The limit of quantification was 2.7 ng/kg, which corresponds to 13.5 % of the target mass fraction in the future certified reference material (20 ng/kg). An uncertainty budget for the measurement of mercury in seawater has been established. The relative expanded (k = 2) combined uncertainty is 6 %. The performance of the validated method was demonstrated by generating results for process control and a homogeneity study for the production of a candidate certified reference material.

A direct HPLC method for the resolution and quantitation of the R-(-)- and S-(+)-enantiomers of vigabatrin (gamma-vinyl-GABA) in pharmaceutical dosage forms using teicoplanin aglycone chiral stationary phase.

PubMed

Al-Majed, Abdulrahman A

2009-08-15

A direct chiral high-performance liquid chromatography (HPLC) method was developed and validated for the resolution and quantification of antiepileptic drug enantiomers, R-(-)- and S-(+)-vigabatrin (gamma-vinyl-gamma-aminobutyric acid) in pharmaceutical products. The separation was optimized on a macrocyclic glycopeptide antibiotic chiral stationary phase (CSP) based on teicoplanin aglycone, chirobiotic (TAG), using a mobile phase system containing ethanol-water (80:20, v/v), at a flow rate of 0.4ml/min and UV detection set at 210nm. The stability of vigabatrin enantiomers under different degrees of temperature was also studied. The enantiomers of vigabatrin were separated from each other. The calibration curves were linear over a range of 100-1600microg/ml (r=0.999) for both enantiomers. The overall recoveries of R-(-)- and S-(+)-vigabatrin enantiomers from pharmaceutical products were in the range of 98.3-99.8% with %RSD ranged from 0.48 to 0.52%. The limit of quantification (LOQ) and limit of detection (LOD) for each enantiomer were 100 and 25microg/ml, respectively. No interferences were found from commonly co-formulated excipients.

On-line supercritical fluid extraction-supercritical fluid chromatography-mass spectrometry of polycyclic aromatic hydrocarbons in soil.

PubMed

Wicker, A Paige; Carlton, Doug D; Tanaka, Kenichiro; Nishimura, Masayuki; Chen, Vivian; Ogura, Tairo; Hedgepeth, William; Schug, Kevin A

2018-06-01

On-line supercritical fluid extraction - supercritical fluid chromatography - mass spectrometry (SFE-SFC-MS) has been applied for the determination of polycyclic aromatic hydrocarbons (PAHs) in soil. The purpose of this study was to develop and validate the first on-line SFE-SFC-MS method for the quantification of PAHs in various types of soil. By coupling the sample extraction on-line with chromatography and detection, sample preparation is minimized, diminishing sample loss and contamination, and significantly decreasing the required extraction time. Parameters for on-line extraction coupled to chromatographic analysis were optimized. The method was validated for concentrations of 10-1500 ng of PAHs per gram of soil in Certified Reference Material (CRM) sediment, clay, and sand with R 2  ≥ 0.99. Limits of detection (LOD) were found in the range of 0.001-5 ng/g, and limits of quantification (LOQ) in the range of 5-15 ng/g. The method developed in this study can be effectively applied to the study of PAHs in the environment, and may lay the foundation for further applications of on-line SFE-SFC-MS. Copyright © 2018 Elsevier B.V. All rights reserved.

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

PubMed

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

2014-05-01

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

Applicability of hybrid linear ion trap-high resolution mass spectrometry and quadrupole-linear ion trap-mass spectrometry for mycotoxin analysis in baby food.

PubMed

Rubert, Josep; James, Kevin J; Mañes, Jordi; Soler, Carla

2012-02-03

Recent developments in mass spectrometers have created a paradoxical situation; different mass spectrometers are available, each of them with their specific strengths and drawbacks. Hybrid instruments try to unify several advantages in one instrument. In this study two of wide-used hybrid instruments were compared: hybrid quadrupole-linear ion trap-mass spectrometry (QTRAP®) and the hybrid linear ion trap-high resolution mass spectrometry (LTQ-Orbitrap®). Both instruments were applied to detect the presence of 18 selected mycotoxins in baby food. Analytical parameters were validated according to 2002/657/CE. Limits of quantification (LOQs) obtained by QTRAP® instrument ranged from 0.45 to 45 μg kg⁻¹ while lower limits of quantification (LLOQs) values were obtained by LTQ-Orbitrap®: 7-70 μg kg⁻¹. The correlation coefficients (r) in both cases were upper than 0.989. These values highlighted that both instruments were complementary for the analysis of mycotoxin in baby food; while QTRAP® reached best sensitivity and selectivity, LTQ-Orbitrap® allowed the identification of non-target and unknowns compounds. Copyright © 2011 Elsevier B.V. All rights reserved.

High-performance thin-layer chromatography (HPTLC) for the simultaneous quantification of the cyclic lipopeptides Surfactin, Iturin A and Fengycin in culture samples of Bacillus species.

PubMed

Geissler, Mareen; Oellig, Claudia; Moss, Karin; Schwack, Wolfgang; Henkel, Marius; Hausmann, Rudolf

2017-02-15

A high-performance thin-layer chromatography method has been established for the identification and simultaneous quantification of the cyclic lipopeptides Surfactin, Iturin A and Fengycin in Bacillus culture samples. B. subtilis DSM 10 T , B. amyloliquefaciens DSM 7 T and B. methylotrophicus DSM 23117 were used as model strains. Culture samples indicated that a sample pretreatment is necessary in order to run HPTLC analyses. A threefold extraction of the cell-free broth with the solvent chloroform/methanol (2:1, v/v) gave best results, when all three lipopeptides were included in the analysis. For the mobile phase, a two-step development was considered most suitable. The first development is conducted with chloroform/methanol/water (65:25:4, v/v/v) over a migration distance of 60mm and the second development using butanol/ethanol/0.1% acetic acid (1:4:1, v/v/v) over a migration distance of 60mm, as well. The method was validated according to Validation of Analytical Procedures: Methodology (FDA Guidance) with respect to the parameters linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy and recovery rate. A linear range with R 2 >0.99 was obtained for all samples from 30ng/zone up to 600ng/zone. The results indicated that quantification of Surfactin has to be performed after the first development (hR F =44), while Fengycin is quantified after the second development (hR F =36, hR F range=20-40). For Iturin A, the results demonstrated that quantification is in favor after the first (hR F =19) development, but also possible after the second (hR F =59) development. LOD and LOQ for Surfactin and Iturin A after the first development, and Fengycin after the second development were determined to be 16ng/zone and 47ng/zone, 13ng/zone and 39ng/zone, and 27ng/zone and 82ng/zone, respectively. Results further revealed the highly accurate and precise character of the developed method with a good inter- and intraday reproducibility. For the precision and accuracy, expressed as % recovery and relative standard deviation, respectively, the determined values did not exceed ±15% as specified by the FDA Guidance. The recovery assay conducted for samples obtained from two strains with the solvent chloroform/methanol (2:1, v/v), which was determined to be most suitable if all three lipopeptides are of interest, gave recoveries of 96.5% and 99.6%, 68.6% and 71.6%, and 102.5% and 95.2% for Surfactin, Iturin A and Fengycin, respectively. Overall, a suitable and reliable method for the simultaneous quantification of the lipopeptides Surfactin, Iturin A and Fengycin in biological samples using HPTLC was successfully developed and validated. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative Analysis of Staphylococcal Enterotoxins A and B in Food Matrices Using Ultra High-Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS/MS).

PubMed

Muratovic, Aida Zuberovic; Hagström, Thomas; Rosén, Johan; Granelli, Kristina; Hellenäs, Karl-Erik

2015-09-11

A method that uses mass spectrometry (MS) for identification and quantification of protein toxins, staphylococcal enterotoxins A and B (SEA and SEB), in milk and shrimp is described. The analysis was performed using a tryptic peptide, from each of the toxins, as the target analyte together with the corresponding (13)C-labeled synthetic internal standard peptide. The performance of the method was evaluated by analyzing spiked samples in the quantification range 2.5-30 ng/g (R² = 0.92-0.99). The limit of quantification (LOQ) in milk and the limit of detection (LOD) in shrimp was 2.5 ng/g, for both SEA and SEB toxins. The in-house reproducibility (RSD) was 8%-30% and 5%-41% at different concentrations for milk and shrimp, respectively. The method was compared to the ELISA method, used at the EU-RL (France), for milk samples spiked with SEA at low levels, in the quantification range of 2.5 to 5 ng/g. The comparison showed good coherence for the two methods: 2.9 (MS)/1.8 (ELISA) and 3.6 (MS)/3.8 (ELISA) ng/g. The major advantage of the developed method is that it allows direct confirmation of the molecular identity and quantitative analysis of SEA and SEB at low nanogram levels using a label and antibody free approach. Therefore, this method is an important step in the development of alternatives to the immune-assay tests currently used for staphylococcal enterotoxin analysis.

Simultaneous analysis of carbohydrates and organic acids by HPLC-DAD-RI for monitoring goat's milk yogurts fermentation.

PubMed

da Costa, Marion Pereira; Frasao, Beatriz da Silva; Lima, Bruno Reis Carneiro da Costa; Rodrigues, Bruna Leal; Conte Junior, Carlos Adam

2016-05-15

During yogurt manufacture, the lactose fermentation and organic acid production can be used to monitor the fermentation process by starter cultures and probiotic bacteria. In the present work, a simple, sensitive and reproducible high-performance liquid chromatography with dual detectors, diode array detector and refractive index was validated by simultaneous analysis of carbohydrates and organic acids in goat milk yogurts. In addition, pH and bacterial analysis were performed. Separation of all the compounds was performed on an Aminex HPX-87H column (300×7.8 mm, 9 µm) utilizing a 3 mmol L(-1) sulfuric acid aqueous mobile phase under isocratic conditions. Lactose, glucose, galactose, citric, lactic and formic acids were used to evaluate the following performance parameters: selectivity, linearity, precision, limit of detection (LOD), limit of quantification (LOQ), decision limits (CCα), detection capabilities (CCβ), recovery and robustness. For the method application a six goat milk yogurts were elaborated: natural, probiotic, prebiotic, symbiotic, cupuassu fruit pulp, and probiotic with cupuassu fruit pulp. The validated method presented an excellent selectivity with no significant matrix effect, and a broad linear study range with coefficients of determination higher than 0.995. The relative standard deviation was lower than 10% under repeatability and within-laboratory reproducibility conditions for the studied analytes. The LOD of the method was defined from 0.001 to 0.003 µg g(-1), and the LOQ from 0.003 to 0.013 µg g(-1). The CCα was ranged from 0.032 to 0.943 µg g(-1), and the CCβ from 0.053 to 1.604 µg g(-1). The obtained recovery values were from 78% to 119%. In addition, the method exhibited an appropriate robustness for all parameter evaluated. Base in our data, it was concluded that the performance parameters demonstrated total method adequacy for the detection and quantification of carbohydrates and organic acids in goat milk yogurts. The application of the method was successfully applied to monitoring different goat milk yogurts during fermentation. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of an HPLC method for determination of metabolic compounds in myocardial tissue.

PubMed

Volonté, M G; Yuln, G; Quiroga, P; Consolini, A E

2004-05-28

The determination of adenine nucleotides and creatine compounds has great importance in the characterization of ischemic myocardial injury and post-ischemic recovery. It was developed by an HPLC method for the quantification of creatine (Cr), creatine phosphate (CrP), hypoxanthine (HX), AMP, adenosine (Ad), ADP and ATP in isolated perfused rat hearts. The chromatographic conditions were: RP 18 column; mobile phase composed by KH(2)PO(4) (215 mM), tetrabutylammonium hydrogen sulfate (2.3mM), acetonitrile (4%) and KOH (1M 0.4%); flow rate 1 ml min(-1); temperature 25 degrees C; injection volume 20 microl; detection at 220 nm and height peak (HP) as the integration parameter. The method was validated by means of linearity and sensitivity evaluations, using calibration curves done with five concentration levels of each compound. The limits of quantification (LOQ) were also determined. The system precision was calculated as the coefficient of variation for five injections for each compound tested. The purity of the peaks was established using enzymatic peak shift analysis with hexokinase and creatine kinase and also comparing HP at various wavelengths. Frozen hearts were homogenized with a mechanical homogenizer for 3 min at 0 degrees C added with 5 ml of 0.4N HCLO(4). After precipitation with 0.8 ml of 2M KOH the extract was shaked for 2 min and later centrifuged at 0 degrees C for 10 min. The supernatant was kept on ice, filtrated and injected into the HPLC system. The results show that the method for the determination of Cr, CrP, HX, AMP, Ad, ADP and ATP by HPLC here described has good linearity, LOQ, precision, specificity and is simple and rapid to perform.

Solid-phase extraction followed by liquid chromatography quadrupole time-of-flight tandem mass spectrometry for the selective determination of fungicides in wine samples.

PubMed

Fontana, A R; Rodríguez, I; Ramil, M; Altamirano, J C; Cela, R

2011-04-22

In this work, a reliable and selective procedure for the determination of thirteen fungicides in red and white wine samples is proposed. Solid-phase extraction (SPE) and liquid chromatography (LC) tandem mass spectrometry (MS/MS), based on a hybrid quadrupole time-of-flight (QTOF) system, were used as sample preparation and determination techniques, respectively. Extraction and purification of target analytes was carried out simultaneously by using a reversed-phase Oasis HLB (200mg) SPE cartridge combined with acetonitrile as elution solvent. Fungicides were determined operating the electrospray source in the positive ionization mode, with MS/MS conditions adjusted to obtain at least two intense product ions per compound, or registering two transitions per species when a single product was noticed. High selective MS/MS chromatograms were extracted using a mass window of 20 ppms for each product ion. Considering external calibration as quantification technique, the overall recoveries (accuracy) of the procedure ranged between 81% and 114% for red and white wine samples (10-20 mL), spiked at different concentrations between 5 and 100 ng mL(-1). Relative standard deviations of the above data stayed below 12% and the limits of quantification (LOQs) of the method, calculated for 10 mL of wine, varied between 0.1 ng mL(-1) for cyprodinil (CYP) and 0.7 ng mL(-1) for myclobutanil (MYC). The optimized method was applied to seventeen commercial wines produced in Spain and obtained from local supermarkets. Nine fungicides were determined, at levels above the LOQs of the method, in the above samples. The maximum concentrations and the highest occurrence frequencies corresponded to metalaxyl (MET) and iprovalicarb (IPR). Copyright © 2011 Elsevier B.V. All rights reserved.

Complete automation of solid-phase extraction with subsequent liquid chromatography-tandem mass spectrometry for the quantification of benzoylecgonine, m-hydroxybenzoylecgonine, p-hydroxybenzoylecgonine, and norbenzoylecgonine in urine--application to a high-throughput urine analysis laboratory.

PubMed

Robandt, Paul P; Reda, Louis J; Klette, Kevin L

2008-10-01

A fully automated system utilizing a liquid handler and an online solid-phase extraction (SPE) device coupled with liquid chromatography-tandem mass spectrometry (LC-MS-MS) was designed to process, detect, and quantify benzoylecgonine (BZE), meta-hydroxybenzoylecgonine (m-OH BZE), para-hydroxybenzoylecgonine (p-OH BZE), and norbenzoylecgonine (nor-BZE) metabolites in human urine. The method was linear for BZE, m-OH BZE, and p-OH BZE from 1.2 to 10,000 ng/mL with limits of detection (LOD) and quantification (LOQ) of 1.2 ng/mL. Nor-BZE was linear from 5 to 10,000 ng/mL with an LOD and LOQ of 1.2 and 5 ng/mL, respectively. The intrarun precision measured as the coefficient of variation of 10 replicates of a 100 ng/mL control was less than 2.6%, and the interrun precision for 5 replicates of the same control across 8 batches was less than 4.8% for all analytes. No assay interference was noted from controls containing cocaine, cocaethylene, and ecgonine methyl ester. Excellent data concordance (R2 > 0.994) was found for direct comparison of the automated SPE-LC-MS-MS procedure and an existing gas chromatography-MS procedure using 94 human urine samples previously determined to be positive for BZE. The automated specimen handling and SPE procedure, when compared to the traditional extraction schema, eliminates the human factors of specimen handling, processing, extraction, and derivatization, thereby reducing labor costs and rework resulting from batch handling issues, and may reduce the number of fume hoods required in the laboratory.

Determination of N,N-dimethyltryptamine and beta-carboline alkaloids in human plasma following oral administration of Ayahuasca.

PubMed

Yritia, Mercedes; Riba, Jordi; Ortuño, Jordi; Ramirez, Ariel; Castillo, Araceli; Alfaro, Yolanda; de la Torre, Rafael; Barbanoj, Manel J

2002-11-05

Ayahuasca is a South American psychotropic beverage prepared from plants native to the Amazon River Basin. It combines the hallucinogenic agent and 5-HT(2A/2C) agonist N,N-dimethyltryptamine (DMT) with beta-carboline alkaloids showing monoamine oxidase-inhibiting properties. In the present paper, an analytical methodology for the plasma quantification of the four main alkaloids present in ayahuasca plus two major metabolites is described. DMT was extracted by liquid-liquid extraction with n-pentane and quantified by gas chromatography with nitrogen-phosphorus detection. Recovery was 74%, and precision and accuracy were better than 9.9%. The limit of quantification (LOQ) was 1.6 ng/ml. Harmine, harmaline, and tetrahydroharmine (THH), the three main beta-carbolines present in ayahuasca, and harmol and harmalol (O-demethylation metabolites of harmine and harmaline, respectively) were measured in plasma by means of high-performance liquid chromatography (HPLC) with fluorescence detection. Sample preparation was accomplished by solid-phase extraction, which facilitated the automation of the process. All five beta-carbolines were measured using a single detector by switching wavelengths. Separation of harmol and harmalol required only slight changes in the chromatographic conditions. Method validation demonstrated good recoveries, above 87%, and accuracy and precision better than 13.4%. The LOQ was 0.5 ng/ml for harmine, 0.3 ng/ml for harmaline, 1.0 ng/ml for THH, and 0.3 ng/ml for harmol and harmalol. Good linearity was observed in the concentration ranges evaluated for DMT (2.5-50 ng/ml) and the beta-carbolines (0.3-100 ng/ml). The gas chromatography and HPLC methods described allowed adequate characterization of the pharmacokinetics of the four main alkaloids present in ayahuasca, and also of two major beta-carboline metabolites not previously described in the literature.

Glyphosate in German adults - Time trend (2001 to 2015) of human exposure to a widely used herbicide.

PubMed

Conrad, André; Schröter-Kermani, Christa; Hoppe, Hans-Wolfgang; Rüther, Maria; Pieper, Silvia; Kolossa-Gehring, Marike

2017-01-01

The broadband herbicide glyphosate (N-[phosphonomethyl]-glycine) and its main metabolite aminomethylphosphonic acid (AMPA) were analyzed by GC-MS-MS in 24h-urine samples cryo-archived by the German Environmental Specimen Bank (ESB). Samples collected in 2001, 2003, 2005, 2007, 2009, 2011, 2012, 2013, 2014, and 2015 were chosen for this retrospective analysis. All urine samples had been provided by 20 to 29 years old individuals living in Greifswald, a city in north-eastern Germany. Out of the 399 analyzed urine samples, 127 (=31.8%) contained glyphosate concentrations at or above the limit of quantification (LOQ) of 0.1μg/L. For AMPA this was the case for 160 (=40.1%) samples. The fraction of glyphosate levels at or above LOQ peaked in 2012 (57.5%) and 2013 (56.4%) after having discontinuously increased from 10.0% in 2001. Quantification rates were lower again in 2014 and 2015 with 32.5% and 40.0%, respectively. The overall trend for quantifiable AMPA levels was similar. Glyphosate and AMPA concentrations in urine were statistically significantly correlated (spearman rank correlation coefficient=0.506, p≤0.001). Urinary glyphosate and AMPA levels tended to be higher in males. The possible reduction in exposure since 2013 indicated by ESB data may be due to changes in glyphosate application in agricultural practice. The ESB will continue monitoring internal exposures to glyphosate and AMPA for following up the time trend, elucidating inter-individual differences, and contributing to the ongoing debate on the further regulation of glyphosate-based pesticides. Copyright © 2016 The Authors. Published by Elsevier GmbH.. All rights reserved.

Determination of ultratrace levels of tributyltin in waters by isotope dilution and gas chromatography coupled to tandem mass spectrometry.

PubMed

Rodríguez-Cea, Andrés; Rodríguez-González, Pablo; Font Cardona, Nuria; Aranda Mares, José Luís; Ballester Nebot, Salomé; García Alonso, J Ignacio

2015-12-18

The current EU legislation lays down the Environmental Quality Standards (EQS) of 45 priority substances in surface water bodies. In particular, the concentration of tributyltin (TBT) must not exceed 0.2ngL(-1) and analytical methodologies with a Limit of Quantification (LOQ) equal or below 0.06ngL(-1) are urged to be developed. This work presents a procedure for the determination of ultratrace levels of TBT in water samples by Isotope Dilution and GC-MS/MS operating in Selected Reaction Monitoring (SRM) mode which meets current EU requirements. The method requires the monitorization of five consecutive transitions (287>175 to 291>179) for the sensitive and selective detection of TBT. The measured isotopic distribution of TBT fragment ions was in agreement with the theoretical values computed by a polynomial expansion algorithm. The combined use of Tandem Mass Spectrometry, a sample volume of 250mL, the preconcentration of 1mL of organic phase to 30μL and an injection volume of 25μL by Programmed Temperature Vaporization provided a LOQ of 0.0426ngL(-1) for TBT (calculated as ten times the standard deviation of nine independent blanks). The recovery for TBT calculated in Milli-Q water at the EQS level was 106.3±4%. A similar procedure was also developed for the quantification of dibutyltin (DBT) and monobutyltin (MBT) in water samples showing satisfactory results. The method was finally implemented in a routine testing laboratory to demonstrate its applicability to real samples obtaining quantitative recoveries for TBT at the EQS level in mineral water, river water and seawater. Copyright © 2015 Elsevier B.V. All rights reserved.

Validation of a QuEChERS-based gas chromatographic method for analysis of pesticide residues in Cassia angustifolia (senna).

PubMed

Tripathy, Vandana; Saha, Ajoy; Patel, Dilipkumar J; Basak, B B; Shah, Paresh G; Kumar, Jitendra

2016-08-02

A simple multi-residue method based on modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach was established for the determination of 17 organochlorine (OC), 15 organophosphorous (OP) and 7 synthetic pyrethroid (SP) pesticides in an economically important medicinal plant of India, Senna (Cassia angustifolia), by gas chromatography coupled to electron capture and flame thermionic detectors (GC/ECD/FTD) and confirmation of residues was done on gas chromatograph coupled with mass spectrometry (GC-MS). The developed method was validated by testing the following parameters: linearity, limit of detection (LOD), limit of quantification (LOQ), matrix effect, accuracy-precision and measurement uncertainty; the validation study clearly demonstrated the suitability of the method for its intended application. All pesticides showed good linearity in the range 0.01-1.0 μg mL(-1) for OCs and OPs and 0.05-2.5 μg mL(-1) for SPs with correlation coefficients higher than 0.98. The method gave good recoveries for most of the pesticides (70-120%) with intra-day and inter-day precision < 20% in most of the cases. The limits of detection varied from 0.003 to 0.03 mg kg(-1), and the LOQs were determined as 0.01-0.049 mg kg(-1). The expanded uncertainties were <30%, which was distinctively less than a maximum default value of ±50%. The proposed method was successfully applied to determine pesticide residues in 12 commercial market samples obtained from different locations in India.

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.

A liquid chromatography-tandem mass spectrometry-based targeted proteomics assay for monitoring P-glycoprotein levels in human breast tissue.

PubMed

Yang, Ting; Chen, Fei; Xu, Feifei; Wang, Fengliang; Xu, Qingqing; Chen, Yun

2014-09-25

P-glycoprotein (P-gp) can efflux drugs from cancer cells, and its overexpression is commonly associated with multi-drug resistance (MDR). Thus, the accurate quantification of P-gp would help predict the response to chemotherapy and for prognosis of breast cancer patients. An advanced liquid chromatography-tandem mass spectrometry (LC/MS/MS)-based targeted proteomics assay was developed and validated for monitoring P-gp levels in breast tissue. Tryptic peptide 368IIDNKPSIDSYSK380 was selected as a surrogate analyte for quantification, and immuno-depleted tissue extract was used as a surrogate matrix. Matched pairs of breast tissue samples from 60 patients who were suspected to have drug resistance were subject to analysis. The levels of P-gp were quantified. Using data from normal tissue, we suggested a P-gp reference interval. The experimental values of tumor tissue samples were compared with those obtained from Western blotting and immunohistochemistry (IHC). The result indicated that the targeted proteomics approach was comparable to IHC but provided a lower limit of quantification (LOQ) and could afford more reliable results at low concentrations than the other two methods. LC/MS/MS-based targeted proteomics may allow the quantification of P-gp in breast tissue in a more accurate manner. Copyright © 2014 Elsevier B.V. All rights reserved.

Novel Spectrophotometric Method for the Assay of Captopril in Dosage Forms using 2,6-Dichloroquinone-4-Chlorimide

PubMed Central

El-Enany, Nahed; Belal, Fathalla; Rizk, Mohamed

2008-01-01

A simple spectrophotometric method was developed for the determination of captopril (CPL) in pharmaceutical preparations. The method is based on coupling captopril with 2,6-dichloroquinone-4-chlorimide (DCQ) in dimethylsulphoxide. The yellow reaction product was measured at 443 nm. The absorbance–concentration plot was rectilinear over the range of 10-50 μg/mL with minimum detection limit (LOD) of 0.66 μg/mL and a quantification limit (LOQ) of 2.0 μg/mL. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The proposed method was successfully applied to the analysis of commercial tablets and the results were in good agreement with those obtained using official and reference spectrophotometric methods. Hydrochlorothiazide which is frequently co-formulated with CPL did not interfere with the assay. A proposal of the reaction pathway was presented. PMID:23675082

Detection of Xeljanz enantiomers in diethyl amine active pharmaceutical ingredients and tablets.

PubMed

Wang, Na-Na; Zhang, Dao-Lin; Jiang, Xin-Hui

2015-03-01

A high-performance liquid chromatography (HPLC) method was established to detect Xeljanz enantiomers in active pharmaceutical ingredients (APIs) and tablets. The separation was achieved on a Chiralpak IC column using a mobile phase of hexane-ethanol-diethylamine (65:35:0.1, v/v). The detection wavelength was 289 nm. The peak areas and the enantiomer concentrations in the range of 0.15-2.25 μg•mL(-1) were in high linearity, with correlation coefficients higher than 0.999. The recoveries were 86.44% at the concentrations of 7.5, 18.75, and 37.5 μg•mL(-1) . The limit of detection (LOD) and limit of quantification (LOQ) were 0.042 and 0.14 μg•mL(-1) , respectively. This HPLC method is suitable for detecting the enantiomers of Xeljanz in its APIs and tablets. © 2014 Wiley Periodicals, Inc.

Enhancing Activity and Stability of Uricase from Lactobacillus plantarum by Zeolite immobilization

NASA Astrophysics Data System (ADS)

Iswantini, D.; Nurhidayat, N.; Sarah

2017-03-01

Lactobacillus plantarum has been known be able to produce uricase for uric acid biosensor. Durability and stability of L. plantarum in generating uricase enzyme was low. Hence, we tried to enhance its durability and stability by immobilizing it onto activated 250 mg zeolite at room temperature using 100 μL L.plantarum suspension and 2.87 mM uric acid, while Michaelis-Menten constant (KM) and Vmax were obtained at 6.7431 mM and 0.9171 µA consecutively, and the linearity range was 0.1-3.3 mM (R2 = 0.9667). Limit of detection (LOD) and limit of quantification (LOQ) value of the measurement were 0.4827 mM and 1.6092 mM respectively. Biosensor stability treatment was carried out in two different treatments, using the same electrode and using disposable electrode. The disposable electrode stability showed better result based on repeated measurements, but stability was still need improvement.

A highly selective and sensitive Tb3+-acetylacetone photo probe for the assessment of acetazolamide in pharmaceutical and serum samples

NASA Astrophysics Data System (ADS)

Youssef, A. O.

2018-04-01

A novel, simple, sensitive and selective spectrofluorimetric method was developed for the determination of Acetazolamide in pharmaceutical tablets and serum samples using photo probe Tb3+-ACAC. The Acetazolamide can remarkably quench the luminescence intensity of Tb3+-ACAC complex in DMSO at pH 6.8 and λex = 350 nm. The quenching of luminescence intensity of Tb3+-ACAC complex especially the electrical band at λem = 545 nm is used for the assessment of Acetazolamide in the pharmaceutical tablet and serum samples. The dynamic range found for the determination of Acetazolamide concentration is 4.49 × 10-9-1.28 × 10-7 mol L-1, and the limit of detection (LOD) and limit of quantification (LOQ) are (4.0 × 10-9 and 1.21 × 10-8) mol L-1, respectively.

High-performance liquid chromatographic assay for the determination of Aloe Emodin in mouse plasma.

PubMed

Zaffaroni, M; Mucignat, C; Pecere, T; Zagotto, G; Frapolli, R; D'Incalci, M; Zucchetti, M

2003-10-25

An isocratic high-performance liquid chromatography (HPLC) method was developed and validated to determine Aloe Emodin (AE) in mouse plasma. The analysis required 0.3 ml of plasma and involves extraction with dichloromethane. The HPLC separation was carried out on Symmetry Shield RP18, a mobile phase of methanol-water-acetic acid (65:35:0.2) and fluorescence detection at lambda(ex)=410 nm and lambda(em)=510 nm. The retention time of AE was 11.7 min. The assay was linear from 10 to 1,000 ng/ml (r2 > or = 0.999), showed intra- and inter-day precision within 7.8 and 4.7%, and accuracy of 87.3-105.7%. Detection limit (LOD) and quantification limit (LOQ) were 4.5 and 5 ng/ml, respectively. The method was applied to determine for the first time the pharmacokinetic of AE in mice.

Determination of nitrate esters in water samples Comparison of efficiency of solid-phase extraction and solid-phase microextraction.

PubMed

Jezová, Vera; Skládal, Jan; Eisner, Ales; Bajerová, Petra; Ventura, Karel

2007-12-07

This paper deals with comparison of efficiency of extraction techniques (solid-phase extraction, SPE and solid-phase microextraction, SPME) used for extraction of nitrate esters (ethyleneglycoldinitrate, EGDN and nitroglycerin, NG), representing the first step of the method of quantitative determination of trace concentrations of nitrate esters in water samples. EGDN and NG are subsequently determined by means of high-performance liquid chromatography with ultraviolet detection (HPLC-UV). Optimization of SPE and SPME conditions was carried out using model water samples. Seven SPE cartridges were tested and the conditions were optimized (type of sorbent, type and volume of solvent to be used as eluent). For both nitrate esters the limit of detection (LOD) and the limit of quantification (LOQ) obtained using SPE/HPLC-UV were 0.23 microg mL(-1) and 0.70 microg mL(-1), respectively. Optimization of SPME conditions: type of SPME fibre (four fibres were tested), type and time of sorption/desorption, temperature of sorption. PDMS/DVB (polydimethylsiloxane/divinylbenzene) fibre coating proved to be suitable for extraction of EGDN and NG. For this fibre the LOD and the LOQ for both nitrate esters were 0.16 microg mL(-1) and 0.50 microg mL(-1), respectively. Optimized methods SPE/HPLC-UV and SPME/HPLC-UV were then used for quantitative determination of nitrate esters content in real water samples from the production of EGDN and NG.

A Simple and Fast Extraction Method for the Determination of Multiclass Antibiotics in Eggs Using LC-MS/MS.

PubMed

Wang, Kun; Lin, Kunde; Huang, Xinwen; Chen, Meng

2017-06-21

The purpose of this study was to develop and validate a simple, fast, and specific extraction method for the analysis of 64 antibiotics from nine classes (including sulfonamides, quinolones, tetracyclines, macrolides, lincosamide, nitrofurans, β-lactams, nitromidazoles, and cloramphenicols) in chicken eggs. Briefly, egg samples were simply extracted with a mixture of acetonitrile-water (90:10, v/v) and 0.1 mol·L -1 Na 2 EDTA solution assisted with ultrasonic. The extract was centrifuged, condensed, and directly analyzed on a liquid chromatography coupled to tandem mass spectrometry. Compared with conventional cleanup methods (passing through solid phase extract cartridges), the established method demonstrated comparable efficiencies in eliminating matrix effects and higher or equivalent recoveries for most of the target compounds. Typical validation parameters including specificity, linearity, matrix effect, limits of detection (LODs) and quantification (LOQs), the decision limit, detection capability, trueness, and precision were evaluated. The recoveries of target compounds ranged from 70.8% to 116.1% at three spiking levels (5, 20, and 50 μg·kg -1 ), with relative standard deviations less than 14%. LODs and LOQs were in the ranges of 0.005-2.00 μg·kg -1 and 0.015-6.00 μg·kg -1 for all of the antibiotics, respectively. A total of five antibiotics were successfully detected in 22 commercial eggs from local markets. This work suggests that the method is suitable for the analysis of multiclass antibiotics in eggs.

Measurement of methionine level with the LC-ESI-MS/MS method in schizophrenic patients.

PubMed

Kulaksizoglu, S; Kulaksizoglu, B; Ellidag, H Y; Eren, E; Yilmaz, N; Baykal, A

2016-01-01

The purpose of this study was to evaluate plasma methionine levels by using liquid chromatography electrospray ionization-tandem mass spectroscopy (LC-ESI-MS/MS) in schizophrenic patients. A twelve-point standard graph was drawn, and the recovery rate, the intra-day and inter-day coefficients of variation (CV), the limit of detection (LOD), and the limit of quantification (LOQ) were evaluated. The y and R2 values of the standard graph equation were determined as 0.011x + 0.0179 and 0.9989, respectively, and the graph remained linear until the 200 µmol/l level. The intra-day coefficients of variation of the samples (n = 10) containing 8, 28, and 58 µmol/l methionine were determined as 2.68, 3.10, and 3.79%, respectively; while their inter-day coefficients of variation were determined as 2.98, 3.19, and 3.84%. The LOD and LOQ values were determined as 0.04 and 0.1 µmol/l, respectively, while the mean recovery rates were determined as 101.7 and 99.3%. Plasma methionine values were measured as 21.5 (19.5-24,6) µmol/l for the patient group, 17.8 (16.3-20.1) µmol/l for the control group, and the difference between the two groups was statistically significant (p = 0.03). LC-ESI-MS/MS method represents a fairly sensitive, economic, and rapid analysis that requires very little sample and is suitable for measuring methionine levels in schizophrenic patients.

Spectrophotometric and spectrofluorimetric determination of indacaterol maleate in pure form and pharmaceutical preparations: application to content uniformity.

PubMed

El-Ashry, S M; El-Wasseef, D R; El-Sherbiny, D T; Salem, Y A

2015-09-01

Two simple, rapid, sensitive and precise spectrophotometric and spectrofluorimetric methods were developed for the determination of indacaterol maleate in bulk powder and capsules. Both methods were based on the direct measurement of the drug in methanol. In the spectrophotometric method (Method I) the absorbance was measured at 259 nm. The absorbance-concentration plot was rectilinear over the range 1.0-10.0 µg mL(-1) with a lower detection limit (LOD) of 0.078 µg mL(-1) and lower quantification limit (LOQ) of 0.238 µg mL(-1). Meanwhile in the spectrofluorimetric method (Method II) the native fluorescence was measured at 358 nm after excitation at 258 nm. The fluorescence-concentration plot was rectilinear over the range of 1.0-40.0 ng mL(-1) with an LOD of 0.075 ng mL(-1) and an LOQ of 0.226 ng mL(-1). The proposed methods were successfully applied to the determination of indacaterol maleate in capsules with average percent recoveries ± RSD% of 99.94 ± 0.96 for Method I and 99.97 ± 0.81 for Method II. In addition, the proposed methods were extended to a content uniformity test according to the United States Pharmacopoeia (USP) guidelines and were accurate, precise for the capsules studied with acceptance value 3.98 for Method I and 2.616 for Method II. Copyright © 2015 John Wiley & Sons, Ltd.

Comparison of field portable measurements of ultrafine TiO2: X-ray fluorescence, laser-induced breakdown spectroscopy, and Fourier-transform infrared spectroscopy.

PubMed

LeBouf, Ryan F; Miller, Arthur L; Stipe, Christopher; Brown, Jonathan; Murphy, Nate; Stefaniak, Aleksandr B

2013-06-01

Laboratory measurements of ultrafine titanium dioxide (TiO2) particulate matter loaded on filters were made using three field portable methods (X-ray fluorescence (XRF), laser-induced breakdown spectroscopy (LIBS), and Fourier-transform infrared (FTIR) spectroscopy) to assess their potential for determining end-of-shift exposure. Ultrafine TiO2 particles were aerosolized and collected onto 37 mm polycarbonate track-etched (PCTE) filters in the range of 3 to 578 μg titanium (Ti). Limit of detection (LOD), limit of quantification (LOQ), and calibration fit were determined for each measurement method. The LOD's were 11.8, 0.032, and 108 μg Ti per filter, for XRF, LIBS, and FTIR, respectively and the LOQ's were 39.2, 0.11, and 361 μg Ti per filter, respectively. The XRF calibration curve was linear over the widest dynamic range, up to the maximum loading tested (578 μg Ti per filter). LIBS was more sensitive but, due to the sample preparation method, the highest loaded filter measurable was 252 μg Ti per filter. XRF and LIBS had good predictability measured by regressing the predicted mass to the gravimetric mass on the filter. XRF and LIBS produced overestimations of 4% and 2%, respectively, with coefficients of determination (R(2)) of 0.995 and 0.998. FTIR measurements were less dependable due to interference from the PCTE filter media and overestimated mass by 2% with an R(2) of 0.831.

Sandwich enzyme-linked immunosorbent assay for naringin.

PubMed

Qu, Huihua; Wang, Xueqian; Qu, Baoping; Kong, Hui; Zhang, Yue; Shan, Wenchao; Cheng, Jinjun; Wang, Qingguo; Zhao, Yan

2016-01-15

Among the currently used immunoassay techniques, sandwich ELISA exhibits higher specificity, lower cross-reactivity, and a wider working range compared to the corresponding competitive assays. However, it is difficult to obtain a pair of antibodies that can simultaneously bind to two epitopes of a molecule with a molecular weight of less than 1000 Da. Naringin (Nar) is a flavonoid with a molecular mass of 580 Da. The main aim of this study was to develop a sandwich ELISA for detecting Nar. Two hybridomas secreting anti-Nar monoclonal antibodies (mAbs) were produced by fusing splenocytes from a mouse immunised against Nar-bovine serum albumin (BSA) conjugated with a hypoxanthine-aminopterin-thymidine (HAT)-sensitive mouse myeloma cell line; a sandwich ELISA for detecting Nar was developed using these two well-characterised anti-Nar mAbs. The performance of the sandwich assay was further evaluated by limit of detection (LOD), limit of quantification (LOQ), recovery, and interference analyses. A dose-response curve to Nar was obtained with an LOD of 6.78 ng mL(-1) and an LOQ of 13.47 ng mL(-1). The inter-assay and intra-assay coefficients of variation were 4.32% and 7.48%, respectively. The recovery rate of Nar from concentrated Fructus aurantii granules was 83.63%. A high correlation was obtained between HPLC and sandwich ELISA. These results demonstrate that the sandwich ELISA method has higher specificity for Nar than indirect competitive ELISA. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of alternative environmentally friendly matrix solid phase dispersion solid supports for the simultaneous extraction of 15 pesticides of different chemical classes from drinking water treatment sludge.

PubMed

Soares, Karina Lotz; Cerqueira, Maristela Barnes Rodrigues; Caldas, Sergiane Souza; Primel, Ednei Gilberto

2017-09-01

This study describes the development, optimization and validation of a method for the extraction of 15 pesticides of different chemical classes in drinking water treatment sludge (DWTS) by vortex-assisted Matrix Solid Phase Dispersion (MSPD) with determination by gas chromatography coupled to mass spectrometry. It focused on the application of alternative and different solid supports to the extraction step of the MSPD. The main parameters that influenced the extraction were studied in order to obtain better recovery responses. Recoveries ranged from 70 to 120% with RSD below 20% for all analytes. Limits of quantification (LOQ) of the method ranged from 5 to 500 μg kg -1 whereas the analytical curves showed correlation coefficients above 0.997. The method under investigation used low volume of solvent (5 mL), low sample mass (1.5 g) and low mass of chitin (0.5 g), an environmentally friendly support. It has advantages, such as speed, simplicity and low cost material, over other methods. When the method was applied, 4 out of 15 pesticides were detected in the DWTS samples in concentrations below the LOQ. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

PubMed

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

2017-08-29

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

Transfer of Ochratoxin A into Tea and Coffee Beverages

PubMed Central

Malir, Frantisek; Ostry, Vladimir; Pfohl-Leszkowicz, Annie; Toman, Jakub; Bazin, Ingrid; Roubal, Tomas

2014-01-01

Ochratoxin A (OTA) is nephrotoxic, hepatotoxic, immunotoxic, neurotoxic, reprotoxic, teratogenic, and carcinogenic (group 2B), being characterized by species and sex differences in sensitivity. Despite the fact that OTA is in some aspects a controversial topic, OTA is the most powerful renal carcinogen. The aim of this study was to make a small survey concerning OTA content in black tea, fruit tea, and ground roasted coffee, and to assess OTA transfer into beverages. OTA content was measured using a validated and accredited HPLC-FLD method with a limit of quantification (LOQ) of 0.35 ng/g. The OTA amount ranged from LOQ up to 250 ng/g in black tea and up to 104 ng/g in fruit tea. Black tea and fruit tea, naturally contaminated, were used to prepare tea infusions. The transfer from black tea to the infusion was 34.8% ± 1.3% and from fruit tea 4.1% ± 0.2%. Ground roasted coffee naturally contaminated at 0.92 ng/g was used to prepare seven kinds of coffee beverages. Depending on the type of process used, OTA transfer into coffee ranged from 22.3% to 66.1%. OTA intakes from fruit and black tea or coffee represent a non-negligible human source. PMID:25525684

Turbulent flow chromatography TFC-tandem mass spectrometry supporting in vitro/vivo studies of NCEs in high throughput fashion.

PubMed

Verdirame, Maria; Veneziano, Maria; Alfieri, Anna; Di Marco, Annalise; Monteagudo, Edith; Bonelli, Fabio

2010-03-11

Turbulent Flow Chromatography (TFC) is a powerful approach for on-line extraction in bioanalytical studies. It improves sensitivity and reduces sample preparation time, two factors that are of primary importance in drug discovery. In this paper the application of the ARIA system to the analytical support of in vivo pharmacokinetics (PK) and in vitro drug metabolism studies is described, with an emphasis in high throughput optimization. For PK studies, a comparison between acetonitrile plasma protein precipitation (APPP) and TFC was carried out. Our optimized TFC methodology gave better S/N ratios and lower limit of quantification (LOQ) than conventional procedures. A robust and high throughput analytical method to support hepatocyte metabolic stability screening of new chemical entities was developed by hyphenation of TFC with mass spectrometry. An in-loop dilution injection procedure was implemented to overcome one of the main issues when using TFC, that is the early elution of hydrophilic compounds that renders low recoveries. A comparison between off-line solid phase extraction (SPE) and TFC was also carried out, and recovery, sensitivity (LOQ), matrix effect and robustness were evaluated. The use of two parallel columns in the configuration of the system provided a further increase of the throughput. Copyright 2009 Elsevier B.V. All rights reserved.

Evaluation of High-Throughput Chemical Exposure Models ...

EPA Pesticide Factsheets

The U.S. EPA, under its ExpoCast program, is developing high-throughput near-field modeling methods to estimate human chemical exposure and to provide real-world context to high-throughput screening (HTS) hazard data. These novel modeling methods include reverse methods to infer parent chemical exposures from biomonitoring measurements and forward models to predict multi-pathway exposures from chemical use information and/or residential media concentrations. Here, both forward and reverse modeling methods are used to characterize the relationship between matched near-field environmental (air and dust) and biomarker measurements. Indoor air, house dust, and urine samples from a sample of 120 females (aged 60 to 80 years) were analyzed. In the measured data, 78% of the residential media measurements (across 80 chemicals) and 54% of the urine measurements (across 21 chemicals) were censored, i.e. below the limit of quantification (LOQ). Because of the degree of censoring, we applied a Bayesian approach to impute censored values for 69 chemicals having at least 15% of measurements above LOQ. This resulted in 10 chemicals (5 phthalates, 5 pesticides) with matched air, dust, and urine metabolite measurements. The population medians of indoor air and dust concentrations were compared to population median exposures inferred from urine metabolites concentrations using a high-throughput reverse-dosimetry approach. Median air and dust concentrations were found to be correl

Occurrence of iodinated X-ray contrast media and their biotransformation products in the urban water cycle.

PubMed

Kormos, Jennifer Lynne; Schulz, Manoj; Ternes, Thomas A

2011-10-15

A LC tandem MS method was developed for the simultaneous determination of four iodinated X-ray contrast media (ICM) and 46 ICM biotransformation products (TPs) in raw and treated wastewater, surface water, groundwater, and drinking water. Recoveries ranged from 70% to 130%, and limits of quantification (LOQ) varied between 1 ng/L and 3 ng/L for surface water, groundwater and drinking water, and between 10 ng/L and 30 ng/L for wastewater. In a conventional wastewater treatment plant, iohexol, iomeprol, and iopromide were transformed to >80%, while iopamidol was transformed to 35%. In total, 26 TPs were detected above their LOQ in WWTP effluents. A significant change in the pattern of ICM TPs was observed after bank filtration and groundwater infiltration under aerobic conditions. Predominately, these TPs are formed at the end of the microbial transformation pathways in batch experiments with soil and sediment. These polar ICM TPs, such as iohexol TP599, iomeprol TP643, iopromide TP701A, and iopromide TP643, were not or only partially removed during drinking water treatment. As a consequence, several ICM TPs were detected in drinking water, at concentration levels exceeding 100 ng/L, with a maximum of 500 ng/L for iomeprol TP687.

Survey of human pharmaceuticals in drinking water in the Czech Republic.

PubMed

Kozisek, Frantisek; Pomykacova, Ivana; Jeligova, Hana; Cadek, Vaclav; Svobodova, Veronika

2013-03-01

The first large-scale assessment of pharmaceuticals in drinking water in the Czech Republic (CR) focused on the detection of five substances. Samples were collected from public water systems supplying 5.3 million people, 50.5% of the Czech population. In the initial survey of tap water from 92 major supply zones using mostly surface water, no pharmaceutical exceeded the limit of quantification (LOQ = 0.5 ng/L). In a second survey, samples were collected from the outlet of 23 water treatment plants (WTPs) considered of high risk because they use surface waters influenced by wastewater. Ibuprofen was the most frequently found pharmaceutical (19 samples), followed by carbamazepine (12), naproxen (8), and diclofenac (3); concentrations ranged from 0.5 to 20.7 ng/L, with medians below 6 ng/L. Concentrations of 17α-ethinylestradiol were below the LOQ. A follow-up survey included tap and outlet samples from eight of the 23 WTPs with the highest concentrations. Pharmaceuticals were quantified in only three tap water samples. Regarding risks to consumers, these results suggest that a relatively small population (<10%) in the CR is exposed to quantifiable concentrations of pharmaceuticals in tap water and that an extremely high margin of safety (several thousand-fold to several million-fold) is associated with these exposures.

HPLC-ELSD Quantification and Centrifugal Partition Chromatography Isolation of 8-O-Acetylharpagide from Oxera coronata (Lamiaceae).

PubMed

Remeur, Camille; Le Borgne, Erell; Gauthier, Léa; Grougnet, Raphaël; Deguin, Brigitte; Poullain, Cyril; Litaudon, Marc

2017-05-01

Iridoid glycosides possess highly functionalised monoterpenoid aglycon with several contiguous stereocentres. For the most common, they are often present in quantities reaching several percentage of the fresh plant weight, and thus they may be regarded as starting material for the synthesis of a number of new chiral and bioactive molecules. To quantify and to isolate 8-O-acetylharpagide (AH) from several extracts of Oxera coronata R.P.J. de Kok, a Lamiaceae species endemic to New Caledonia, using HPLC-ELSD (evaporative light scattering detector) and centrifugal partition chromatography (CPC). Oxera coronata produces high amounts of AH in leaves, twigs and fruits. Water and methanol extracts of these plant parts were prepared. The content of AH in each extract was quantified by HPLC-ELSD, using acetonitrile-water (+0.1% formic acid) gradient elution. The HPLC method was validated for precision, linearity, limit of detection (LOD), limit of quantification (LOQ) and accuracy. A ternary solvent system ethyl acetate/n-propanol/water (3:2:5, v/v/v) was selected and applied to recover the target compound using Spot CPC from the leaves aqueous extract. HPLC-ELSD analysis followed by CPC purification led to the efficient isolation of AH from O. coronata leaves aqueous extract. HPLC-ELSD has proven to be a well-adapted detection and quantification method for iridoid glycosides, while CPC confirmed to be an efficient technique for the isolation of polar compounds. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Quantitative detection method for Roundup Ready soybean in food using duplex real-time PCR MGB chemistry.

PubMed

Samson, Maria Cristina; Gullì, Mariolina; Marmiroli, Nelson

2010-07-01

Methodologies that enable the detection of genetically modified organisms (GMOs) (authorized and non-authorized) in food and feed strongly influence the potential for adequate updating and implementation of legislation together with labeling requirements. Quantitative polymerase chain reaction (qPCR) systems were designed to boost the sensitivity and specificity on the identification of GMOs in highly degraded DNA samples; however, such testing will become economically difficult to cope with due to increasing numbers of approved genetically modified (GM) lines. Multiplexing approaches are therefore in development to provide cost-efficient solution. Construct-specific primers and probe were developed for quantitative analysis of Roundup Ready soybean (RRS) event glyphosate-tolerant soybean (GTS) 40-3-2. The lectin gene (Le1) was used as a reference gene, and its specificity was verified. RRS- and Le1-specific quantitative real-time PCR (qRTPCR) were optimized in a duplex platform that has been validated with respect to limit of detection (LOD) and limit of quantification (LOQ), as well as accuracy. The analysis of model processed food samples showed that the degradation of DNA has no adverse or little effects on the performance of quantification assay. In this study, a duplex qRTPCR using TaqMan minor groove binder-non-fluorescent quencher (MGB-NFQ) chemistry was developed for specific detection and quantification of RRS event GTS 40-3-2 that can be used for practical monitoring in processed food products.

UFLC-ESI-MS/MS analysis of multiple mycotoxins in medicinal and edible Areca catechu.

PubMed

Liu, Hongmei; Luo, Jiaoyang; Kong, Weijun; Liu, Qiutao; Hu, Yichen; Yang, Meihua

2016-05-01

A robust, sensitive and reliable ultra fast liquid chromatography combined with electrospray ionization tandem mass spectrometry (UFLC-ESI-MS/MS) was optimized and validated for simultaneous identification and quantification of eleven mycotoxins in medicinal and edible Areca catechu, based on one-step extraction without any further clean-up. Separation and quantification were performed in both positive and negative modes under multiple reaction monitoring (MRM) in a single run with zearalanone (ZAN) as internal standard. The chromatographic conditions and MS/MS parameters were carefully optimized. Matrix-matched calibration was recommended to reduce matrix effects and improve accuracy, showing good linearity within wide concentration ranges. Limits of quantification (LOQ) were lower than 50 μg kg(-1), while limits of detection (LOD) were in the range of 0.1-20 μg kg(-1). The accuracy of the developed method was validated for recoveries, ranging from 85% to 115% with relative standard deviation (RSD) ≤14.87% at low level, from 75% to 119% with RSD ≤ 14.43% at medium level and from 61% to 120% with RSD ≤ 13.18% at high level, respectively. Finally, the developed multi-mycotoxin method was applied for screening of these mycotoxins in 24 commercial samples. Only aflatoxin B2 and zearalenone were found in 2 samples. This is the first report on the application of UFLC-ESI(+/-)-MS/MS for multi-class mycotoxins in A. catechu. The developed method with many advantages of simple pretreatment, rapid determination and high sensitivity is a proposed candidate for large-scale detection and quantification of multiple mycotoxins in other complex matrixes. Copyright © 2016 Elsevier Ltd. All rights reserved.

An event-specific method for the detection and quantification of ML01, a genetically modified Saccharomyces cerevisiae wine strain, using quantitative PCR.

PubMed

Vaudano, Enrico; Costantini, Antonella; Garcia-Moruno, Emilia

2016-10-03

The availability of genetically modified (GM) yeasts for winemaking and, in particular, transgenic strains based on the integration of genetic constructs deriving from other organisms into the genome of Saccharomyces cerevisiae, has been a reality for several years. Despite this, their use is only authorized in a few countries and limited to two strains: ML01, able to convert malic acid into lactic acid during alcoholic fermentation, and ECMo01 suitable for reducing the risk of carbamate production. In this work we propose a quali-quantitative culture-independent method for the detection of GM yeast ML01 in commercial preparations of ADY (Active Dry Yeast) consisting of efficient extraction of DNA and qPCR (quantitative PCR) analysis based on event-specific assay targeting MLC (malolactic cassette), and a taxon-specific S. cerevisiae assay detecting the MRP2 gene. The ADY DNA extraction methodology has been shown to provide good purity DNA suitable for subsequent qPCR. The MLC and MRP2 qPCR assay showed characteristics of specificity, dynamic range, limit of quantification (LOQ) limit of detection (LOD), precision and trueness, which were fully compliant with international reference guidelines. The method has been shown to reliably detect 0.005% (mass/mass) of GM ML01 S. cerevisiae in commercial preparations of ADY. Copyright © 2016 Elsevier B.V. All rights reserved.

Microfluidic chip based nano liquid chromatography coupled to tandem mass spectrometry for the determination of abused drugs and metabolites in human hair.

PubMed

Zhu, Kevin Y; Leung, K Wing; Ting, Annie K L; Wong, Zack C F; Ng, Winki Y Y; Choi, Roy C Y; Dong, Tina T X; Wang, Tiejie; Lau, David T W; Tsim, Karl W K

2012-03-01

A microfluidic chip based nano-HPLC coupled to tandem mass spectrometry (nano-HPLC-Chip-MS/MS) has been developed for simultaneous measurement of abused drugs and metabolites: cocaine, benzoylecgonine, cocaethylene, norcocaine, morphine, codeine, 6-acetylmorphine, phencyclidine, amphetamine, methamphetamine, MDMA, MDA, MDEA, and methadone in the hair of drug abusers. The microfluidic chip was fabricated by laminating polyimide films and it integrated an enrichment column, an analytical column and a nanospray tip. Drugs were extracted from hairs by sonication, and the chromatographic separation was achieved in 15 min. The drug identification and quantification criteria were fulfilled by the triple quardropule tandem mass spectrometry. The linear regression analysis was calibrated by deuterated internal standards with all of the R(2) at least over 0.993. The limit of detection (LOD) and the limit of quantification (LOQ) were from 0.1 to 0.75 and 0.2 to 1.25 pg/mg, respectively. The validation parameters including selectivity, accuracy, precision, stability, and matrix effect were also evaluated here. In conclusion, the developed sample preparation method coupled with the nano-HPLC-Chip-MS/MS method was able to reveal the presence of drugs in hairs from the drug abusers, with the enhanced sensitivity, compared with the conventional HPLC-MS/MS.

Quantitative determination of total cesium in highly active liquid waste by using liquid electrode plasma optical emission spectrometry.

PubMed

Do, Van-Khoai; Yamamoto, Masahiko; Taguchi, Shigeo; Takamura, Yuzuru; Surugaya, Naoki; Kuno, Takehiko

2018-06-01

A sensitive analytical method for determination of total cesium (Cs) in highly active liquid waste (HALW) by using modified liquid electrode plasma optical emission spectrometry (LEP-OES) is developed in this study. The instrument is modified to measure radioactive samples in a glove box. The effects of important factors, including pulsed voltage sequence and nitric acid concentration, on the emission of Cs are investigated. The limit of detection (LOD) and limit of quantification (LOQ) are 0.005 mg/L and 0.02 mg/L, respectively. The achieved LOD is one order lower than that of recently developed spectroscopic methods using liquid discharge plasma. The developed method is validated by subjecting a simulated HALW sample to inductively coupled plasma mass spectrometry (ICP-MS). The recoveries obtained from a spike-and-recovery test are 96-102%, implying good accuracy. The method is successfully applied to the quantification of Cs in a real HALW sample at the Tokai reprocessing plant in Japan. Apart from dilution and filtration of the HALW sample, no other pre-treatment process is required. The results agree well with the values obtained using gamma spectrometry. The developed method offers a reliable technique for rapid analysis of total Cs in HALW samples. Copyright © 2018 Elsevier B.V. All rights reserved.

UV/Visible Spectroscopic Quantification of Veterinary Anthelmintic Drug Oxfendazole in Pharmaceuticals

NASA Astrophysics Data System (ADS)

Rajendraprasad, N.; Basavaiah, K.

2016-07-01

Oxfendazole (OFA) is a broad spectrum benzimidazole anthelmintic medication used to treat veterinary diseases. Two new, simple, rapid, precise and accurate, and sensitive spectrophotometric methods have been developed and validated for the assay of OFA in its pure form and in its boluses. The first method (method A) is based on the measurement of green colored manganate obtained due to oxidation of OFA by permanganate in an alkaline medium at 610 nm. In the second method (Method B), the chromophoric activity of OFA is measured at 290 nm in the acetic acid-water (1:1) solvent system. OFA has been quantified over the linear ranges of 1.25-12.5 and 1.25-10 μg/mL in method A and method B, respectively, with apparent molar absorptivity values of 2.54 × 104 and 2.13 × 104 L·mol-1·cm-1. The limit of detection (LOD), limit of quantification (LOQ), and Sandell sensitivity values are 0.15 u 0.18 μg/mL, 0.46 and 0.56 μg/mL, and 0.0124 and 0.0148 μg/cm2. The developed methods were successfully applied to determine OFA in the bolus. No interference from adjuvants was observed.

Graphene oxide bound silica for solid-phase extraction of 14 polycyclic aromatic hydrocarbons in mainstream cigarette smoke.

PubMed

Shi, Rui; Yan, Lihong; Xu, Tongguang; Liu, Dongye; Zhu, Yongfa; Zhou, Jun

2015-01-02

Polycyclic aromatic hydrocarbons (PAHs) were considered as a source of carcinogenicity in mainstream cigarette smoke (MSS). Accurate quantification of these components was necessary for assessing public health risk. In our study, a solid-phase extraction (SPE) method using graphene oxide (GO) bound silica as adsorbent for purification of 14 PAHs in MSS was developed. During SPE process, large matrices interferences of MSS were adsorbed on SPE column. The result of FTIR spectra demonstrated that these matrices interferences were adsorbed on GO mainly through OH and CO groups. The concentrations of PAHs in MSS extract were determined by gas chromatography-mass spectrometry (GC-MS). The limit of detection (LOD) and limit of quantification (LOQ) of the developed method for 14 PAHs ranged from 0.05 to 0.36 ng/cig and 0.17 to 1.19 ng/cig, respectively. The accuracy of the measurement of 14 PAHs was from 73 to 116%. The relative standard deviations of intra- and inter-day analysis were less than 7.8% and 13.9%, respectively. Moreover, the developed method was successfully applied for analysis of real cigarette containing 1R5F reference cigarette and 12 top-selling commercial cigarettes in China. Copyright © 2014 Elsevier B.V. All rights reserved.

UPLC-MS/MS Method for Simultaneous Determination of Three Major Metabolites of Mequindox in Holothurian

PubMed Central

Liu, Huihui; Han, Dianfeng; Huang, Hui; Xu, Yingjiang; Gong, Xianghong

2018-01-01

This study developed an ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the detection of three major metabolites of mequindox, including 3-methyl-quinoxaline-2-carboxylic acid, 1-desoxymequindox, and 1,4-bisdesoxymequindox (MQCA, 1-DMEQ, and BDMEQ), in holothurian. Target analytes were simplified with ultrasound-assisted acidolysis extracted without complicated enzymolysis steps. After that, each sample was centrifuged and purified by an Oasis MAX cartridge. Then, the processed samples were separated and monitored by UPLC-MS/MS. This developed method has been validated according to FDA criteria. At fortified levels of 2, 10, and 20 μg/kg, recoveries ranged from 82.5% to 93.5% with the intraday RSD less than 7.27% and interday RSD less than 11.8%. The limit of detection (LOD) of all the three metabolites ranged from 0.21 to 0.48 μg/kg, while the limit of quantification (LOQ) ranged from 0.79 to 1.59 μg/kg. On application to commercial samples, 14 of 20 samples were detected positive for the three target analytes, with positive rate at 70 percentage. The result indicated that this method was specific, sensitive, and suitable for the quantification and conformation of the three major metabolites of MEQ in holothurian. PMID:29805832

UPLC-MS/MS Method for Simultaneous Determination of Three Major Metabolites of Mequindox in Holothurian.

PubMed

Liu, Huihui; Ren, Chuanbo; Han, Dianfeng; Huang, Hui; Zou, Rongjie; Zhang, Huawei; Xu, Yingjiang; Gong, Xianghong; Zhang, Xiuzhen; Li, Yanshen

2018-01-01

This study developed an ultraperformance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the detection of three major metabolites of mequindox, including 3-methyl-quinoxaline-2-carboxylic acid, 1-desoxymequindox, and 1,4-bisdesoxymequindox (MQCA, 1-DMEQ, and BDMEQ), in holothurian. Target analytes were simplified with ultrasound-assisted acidolysis extracted without complicated enzymolysis steps. After that, each sample was centrifuged and purified by an Oasis MAX cartridge. Then, the processed samples were separated and monitored by UPLC-MS/MS. This developed method has been validated according to FDA criteria. At fortified levels of 2, 10, and 20  μ g/kg, recoveries ranged from 82.5% to 93.5% with the intraday RSD less than 7.27% and interday RSD less than 11.8%. The limit of detection (LOD) of all the three metabolites ranged from 0.21 to 0.48  μ g/kg, while the limit of quantification (LOQ) ranged from 0.79 to 1.59  μ g/kg. On application to commercial samples, 14 of 20 samples were detected positive for the three target analytes, with positive rate at 70 percentage. The result indicated that this method was specific, sensitive, and suitable for the quantification and conformation of the three major metabolites of MEQ in holothurian.

Development of an Ion-Pairing Reagent and HPLC-UV Method for the Detection and Quantification of Six Water-Soluble Vitamins in Animal Feed.

PubMed

Kim, Ho Jin

2016-01-01

A novel and simple method for detecting six water-soluble vitamins in animal feed using high performance liquid chromatography equipped with a photodiode array detector (HPLC/PDA) and ion-pairing reagent was developed. The chromatographic peaks of the six water-soluble vitamins were successfully identified by comparing their retention times and UV spectra with reference standards. The mobile phase was composed of buffers A (5 mM PICB-6 in 0.1% CH3COOH) and B (5 mM PICB-6 in 65% methanol). All peaks were detected using a wavelength of 270 nm. Method validation was performed in terms of linearity, sensitivity, selectivity, accuracy, and precision. The limits of detection (LODs) for the instrument employed in these experiments ranged from 25 to 197 μg/kg, and the limits of quantification (LOQs) ranged from 84 to 658 μg/kg. Average recoveries of the six water-soluble vitamins ranged from 82.3% to 98.9%. Method replication resulted in intraday and interday peak area variation of <5.6%. The developed method was specific and reliable and is therefore suitable for the routine analysis of water-soluble vitamins in animal feed.

A novel approach for determination of free fatty acids in vegetable oils by a flow injection system with manual injection.

PubMed

Ayyildiz, H Filiz; Kara, Huseyin; Sherazi, S T H

2011-12-01

A non-aqueous flow injection method for determining free fatty acid (FFA) content in corn and sunflower oil samples was developed. A single-line manifold system was built by modification of an HPLC for flow injection analysis (FIA). Without pre-treatment, oil samples were injected into a n-propanol solution containing KOH and phenolphthalein (PHP). The main parameters, such as flow rate of carrier phase, length, geometry, inner diameters of the coils and reagent concentration were all optimized. The proposed FIA method was validated for precision, accuracy, linear region, limit of detection (LOD) and limit of quantification (LOQ). The intra- and inter-day measurements of the precision of the method were found to be within the limits of acceptance criteria (RSD < 1%), and were rugged when the method was performed by a different analyst. The linear concentration range was calculated as 0.09-1.50 and 0.07-1.40 FFA% for corn and sunflower oils, correspondingly. The LOD and LOQ were found to be 7.53 × 10(-4)-2.28 × 10(-3) oleic acid % and 7.11 × 10(-4)-2.23 × 10(-3) oleic acid % for corn and sunflower oils, respectively. The results were compared with those obtained by the AOCS (Ca-5a-40) method using statistical t and F tests, and a significant difference was not observed between the methods at a 95% confidence level. The proposed method is suitable for quality control of routine applications due to its simplicity, high sample throughput, and economy of solvents and sample, offering considerable promise as a low cost analytical system that needs minimum human intervention over long periods of time.

3-Monochloro-1,2-propandiol (3-MCPD) in soy sauce from the Bulgarian market.

PubMed

Christova-Bagdassarian, Valentina; Tishkova, Julieta A; Vrabcheva, Terry M

2013-01-01

The 3-monochloro-1,2-propandiol (3-MCPD) levels in soy sauces which contained hydrolysed vegetable protein were evaluated for the Bulgarian market. For analysis of 3-MCPD, a gas chromatography-mass spectrometry (GC-MS) method was applied with a linear range of 0.03-2.00 μg mL⁻¹ and a limit of detection (LOD) of 2.3 μg kg⁻¹ and a limit of quantification (LOQ) of 3.4 μg kg⁻¹. At these levels, the standard deviation was 5.1%, with recoveries between 81% and 102%. The method was applied to the analysis of 21 samples of soy sauce from the Bulgarian market. Results ranged from 3.7 to 185.6 μg kg⁻¹. Soy sauces produced from hydrolysed soy protein contained higher levels of 3-MCPD than naturally fermented sauces. In 38.4% of samples of Bulgarian origin, the 3-MCPD content was above the EU limit of 20 μg kg⁻¹. In all analysed samples, 33.3% had a 3-MCPD content above the EU limit.

A fluorescent-based HPLC assay for quantification of cysteine and cysteamine adducts in Escherichia coli-derived proteins.

PubMed

Soriano, Brian D; Tam, Lei-Ting T; Lu, Hsieng S; Valladares, Violeta G

2012-01-01

Recombinant proteins expressed in Escherichia coli are often produced as unfolded, inactive forms accumulated in inclusion bodies. Redox-coupled thiols are typically employed in the refolding process in order to catalyze the formation of correct disulfide bonds at maximal folding efficiency. These thiols and the recombinant proteins can form mixed disulfide bonds to generate thiol-protein adducts. In this work, we apply a fluorescent-based assay for the quantification of cysteine and cysteamine adducts as observed in E. coli-derived proteins. The thiols are released by reduction of the adducted protein, collected and labeled with a fluorescent reagent, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. The derivatized thiols are separated by reversed-phase HPLC and can be accurately quantified after method optimization. The estimated thiol content represents total amount of adducted forms present in the analyzed samples. The limit of quantification (LOQ) was established; specifically, the lowest amount of quantifiable cysteine adduction is 30 picograms and the lowest amount of quantifiable cysteamine adduction is 60 picograms. The assay is useful for quantification of adducts in final purified products as well as in-process samples from various purification steps. The assay indicates that the purification process accomplishes a decrease in cysteine adduction from 0.19 nmol adduct/nmol protein to 0.03 nmol adduct/nmol protein as well as a decrease in cysteamine adduction from 0.24 nmol adduct/nmol protein to 0.14 nmol adduct/nmol protein. Copyright © 2011. Published by Elsevier B.V.

Quantification of steroid hormones in human serum by liquid chromatography-high resolution tandem mass spectrometry.

PubMed

Matysik, Silke; Liebisch, Gerhard

2017-12-01

A limited specificity is inherent to immunoassays for steroid hormone analysis. To improve selectivity mass spectrometric analysis of steroid hormones by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been introduced in the clinical laboratory over the past years usually with low mass resolution triple-quadrupole instruments or more recently by high resolution mass spectrometry (HR-MS). Here we introduce liquid chromatography-high resolution tandem mass spectrometry (LC-MS/HR-MS) to further increase selectivity of steroid hormone quantification. Application of HR-MS demonstrates an enhanced selectivity compared to low mass resolution. Separation of isobaric interferences reduces background noise and avoids overestimation. Samples were prepared by automated liquid-liquid extraction with MTBE. The LC-MS/HR-MS method using a quadrupole-Orbitrap analyzer includes eight steroid hormones i.e. androstenedione, corticosterone, cortisol, cortisone, 11-deoxycortisol, 17-hydroxyprogesterone, progesterone, and testosterone. It has a run-time of 5.3min and was validated according to the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) guidelines. For most of the analytes coefficient of variation were 10% or lower and LOQs were determined significantly below 1ng/ml. Full product ion spectra including accurate masses substantiate compound identification by matching their masses and ratios with authentic standards. In summary, quantification of steroid hormones by LC-MS/HR-MS is applicable for clinical diagnostics and holds also promise for highly selective quantification of other small molecules. Copyright © 2017 Elsevier B.V. All rights reserved.

An efficient separation and method development for the quantifying of two basic impurities of Nicergoline by reversed-phase high performance liquid chromatography using ion-pairing counter ions.

PubMed

Yalçin, Güler; Yüktaş, Nüray

2006-10-11

A quantification method was developed for the two basic impurities, one of which is also a metabolite, of Nicergoline (NIC), by using reversed-phase high performance liquid chromatography (RP-HPLC) and diode array detector (DAD). One of these compounds,10-methoxy-6-methylergoline-8beta-methanol-5-bromo-3-pyridinecarboxylate (1-DN) is the metabolite as well as the impurity whereas, the other 10-methoxy-1,6-dimethylergoline-8beta-methanol-5-chloro-3-pyridinecarboxylate (5-CN) is only an impurity. The chromatographic column was Phenomenex, Luna, 5 microm, C18 (2), 250 mm x 4.6 mm. Mobile phase was 0.1 M ammonium acetate (NH4Ac) solution containing 4 mM 1-octanesulfonicacid sodium salt (OSASS) and 6 mM tetrabutylammonium hydrogen sulphate (TBAHS) (pH: 5.9)/acetonitrile (ACN) (62:38) for 1-DN and (64:36) for 5-CN. Flow rate was 1.0 mL min-1. The diode array detector was operated at 285 nm, band width: 4 nm. Linearity was obtained in the concentration range of 0.032 x 10-5 to 3.828 x 10-5 M, y = 116.88x + 0.2773 (r2 = 0.99989); the limit of detection (LOD) and limit of quantification (LOQ) were determined as 0.012 x 10-5 and 0.041 x 10-5 M for 1-DN, respectively. Linearity was obtained in the concentration range of 0.034 x 10-5 to 4.092 x 10-5 M, y = 104.24x + 0.7486 (r2 = 0.99996); (LOD) and (LOQ) were determined as 0.014 x 10-5 and 0.046 x 10-5 M for 5-CN, respectively. The recovery was 100.65% for 1-DN and 100.32% for 5-CN. The amount of 1-DN in 30 mg NIC was found as 209.65 microg (0.70%) and the amount of 5-CN in 30 mg NIC was found as 27.62 microg (0.09%).

Doxycycline depletion and residues in eggs after oral administration to laying hens.

PubMed

Gajda, Anna; Posyniak, Andrzej

2015-01-01

The depletion of doxycycline (DC) residues in eggs was determined after oral drug administration by drinking water to laying hens. The antibiotic was supplied to birds for 5 consecutive days and the eggs were collected during medication and 18 days after withdrawal. DC residues were determined by LC-MS/MS. DC was isolated from eggs with a solution of 0.02 M of oxalic acid (pH 4), 0.1 M Na2EDTA and acetonitrile. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 2 and 5 µg kg(-1), respectively. Analyses were performed on whole egg, egg white and yolk separately. DC was detectable 24 h after the beginning of administration. The concentration of antibiotic increased daily, resulting in the highest DC concentration in whole eggs at the first day of the withdrawal period. Thirteen days after withdrawal, the content of DC in whole eggs was below the LOQ of the method. However, some differences were found in the depletion curve of DC between egg white and yolk. Residues of DC in egg white were much higher during treatment and 1 day after withdrawal, but later the concentration in egg white decreased fairly rapidly and a higher DC content in egg yolk was observed. The depletion period was shorter for egg white than for yolk, and DC was detected in the egg white until 12 days after withdrawal and 2 days more in egg yolk than in white. DC reached a peak faster in egg white, but the residues were detectable for longer period in the yolk.

An ultra-high performance liquid chromatography method to determine the skin penetration of an octyl methoxycinnamate-loaded liquid crystalline system.

PubMed

Prado, A H; Borges, M C; Eloy, J O; Peccinini, R G; Chorilli, M

2017-10-01

Cutaneous penetration is a critical factor in the use of sunscreen, as the compounds should not reach systemic circulation in order to avoid the induction of toxicity. The evaluation of the skin penetration and permeation of the UVB filter octyl methoxycinnamate (OMC) is essential for the development of a successful sunscreen formulation. Liquid-crystalline systems are innovative and potential carriers of OMC, which possess several advantages, including controlled release and protection of the filter from degradation. In this study, a new and effective method was developed using ultra-high performance liquid chromatography (UPLC) with ultraviolet detection (UV) for the quantitative analysis of penetration of OMC-loaded liquid crystalline systems into the skin. The following parameters were assessed in the method: selectivity, linearity, precision, accuracy, robustness, limit of detection (LOD), and limit of quantification (LOQ). The analytical curve was linear in the range from 0.25 to 250 μg.m-1, precise, with a standard deviation of 0.05-1.24%, with an accuracy in the range from 96.72 to 105.52%, and robust, with adequate values for the LOD and LOQ of 0.1 and 0.25 μg.mL -1, respectively. The method was successfully used to determine the in vitro skin permeation of OMC-loaded liquid crystalline systems. The results of the in vitro tests on Franz cells showed low cutaneous permeation and high retention of the OMC, particularly in the stratum corneum, owing to its high lipophilicity, which is desirable for a sunscreen formulation.

Accuracy in Rietveld quantitative phase analysis: a comparative study of strictly monochromatic Mo and Cu radiations.

PubMed

León-Reina, L; García-Maté, M; Álvarez-Pinazo, G; Santacruz, I; Vallcorba, O; De la Torre, A G; Aranda, M A G

2016-06-01

This study reports 78 Rietveld quantitative phase analyses using Cu  K α 1 , Mo  K α 1 and synchrotron radiations. Synchrotron powder diffraction has been used to validate the most challenging analyses. From the results for three series with increasing contents of an analyte (an inorganic crystalline phase, an organic crystalline phase and a glass), it is inferred that Rietveld analyses from high-energy Mo  K α 1 radiation have slightly better accuracies than those obtained from Cu  K α 1 radiation. This behaviour has been established from the results of the calibration graphics obtained through the spiking method and also from Kullback-Leibler distance statistic studies. This outcome is explained, in spite of the lower diffraction power for Mo radiation when compared to Cu radiation, as arising because of the larger volume tested with Mo and also because higher energy allows one to record patterns with fewer systematic errors. The limit of detection (LoD) and limit of quantification (LoQ) have also been established for the studied series. For similar recording times, the LoDs in Cu patterns, ∼0.2 wt%, are slightly lower than those derived from Mo patterns, ∼0.3 wt%. The LoQ for a well crystallized inorganic phase using laboratory powder diffraction was established to be close to 0.10 wt% in stable fits with good precision. However, the accuracy of these analyses was poor with relative errors near to 100%. Only contents higher than 1.0 wt% yielded analyses with relative errors lower than 20%.

Determination of lasalocid residues in the tissues of broiler chickens by liquid chromatography-tandem mass spectrometry.

PubMed

Tkáčiková, Soňa; Kožárová, Ivona; Mačanga, Ján; Levkut, Martin

2012-01-01

Lasalocid is a polyether ionophoric coccidiostat used for the prevention of coccidiosis in poultry at a prescribed concentration and during a certain time interval. Due to a public health concern about the presence of coccidiostat residues in poultry, the aim of the present study was to determine the levels of lasalocid residues in the edible tissues of broiler chickens (breast muscle, thigh muscle, heart, liver, gizzard, kidneys and skin/fat) fed commercially produced feed containing 100 mg kg⁻¹) of lasalocid in complete feed throughout the 5-day withdrawal period (WP). The residues were investigated by liquid chromatography coupled with electrospray ionisation (ESI) tandem mass spectrometry (MS/MS) with triple quadrupole. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were 0.47 and 1.44 µg kg⁻¹, respectively. The average recovery based on the matrix-fortified calibrations for chicken tissues ranged between 79% and 98%. Lasalocid was found to accumulate in the liver, followed by the heart, skin/fat, kidneys, thigh muscle and gizzard. The lowest concentrations of lasalocid residues were found in the breast muscle. On day 5 of the WP, residue concentrations of lasalocid did not decline below the LOQ of the method, but were far below the maximum residue level (MRL) established for lasalocid in poultry from 20 to 100 µg kg⁻¹ by European Commission Regulation (EU) No. 37/2010. The results confirmed that the WP established for lasalocid is sufficient to ensure the decline of its residues in the tissues of broiler chickens to the safe residue level.

Performance evaluation of laser induced breakdown spectroscopy in the measurement of liquid and solid samples

NASA Astrophysics Data System (ADS)

Bilge, Gonca; Sezer, Banu; Boyaci, Ismail Hakki; Eseller, Kemal Efe; Berberoglu, Halil

2018-07-01

Liquid analysis by using LIBS is a complicated process due to difficulties encountered during the collection of light and formation of plasma in liquid. To avoid these, some applications are performed such as aerosol formation and transforming liquid into solid state. However, performance of LIBS in liquid samples still remains a challenging issue. In this study, performance evaluation of LIBS and parameter optimizations in liquid and solid phase samples were performed. For this purpose, milk was chosen as model sample; milk powder was used as solid sample, and milk was used as liquid sample in the experiments. Different experimental setups have been constructed for each sampling technique, and optimizations were performed to determine suitable parameters such as delay time, laser energy, repetition rate and speed of rotary table for solid sampling technique, and flow rate of carrier gas for liquid sampling technique. Target element was determined as Ca, which is a critically important element in milk for determining its nutritional value and Ca addition. In optimum parameters, limit of detection (LOD), limit of quantification (LOQ) and relative standard deviation (RSD) values were calculated as 0.11%, 0.36% and 8.29% respectively for milk powders samples; while LOD, LOQ and RSD values were calculated as 0.24%, 0.81%, and 10.93% respectively for milk samples. It can be said that LIBS is an applicable method in both liquid and solid samples with suitable systems and parameters. However, liquid analysis requires much more developed systems for more accurate results.

Simultaneous tuning of electric field intensity and structural properties of ZnO: Graphene nanostructures for FOSPR based nicotine sensor.

PubMed

Tabassum, Rana; Gupta, Banshi D

2017-05-15

We report theoretical and experimental realization of a SPR based fiber optic nicotine sensor having coatings of silver and graphene doped ZnO nanostructure onto the unclad core of the optical fiber. The volume fraction (f) of graphene in ZnO was optimized using simulation of electric field intensity. Four types of graphene doped ZnO nanostructures viz. nanocomposites, nanoflowers, nanotubes and nanofibers were prepared using optimized value of f. The morphology, photoluminescence (PL) spectra and UV-vis spectra of these nanostructures were studied. The peak PL intensity was found to be highest for ZnO: graphene nanofibers. The optimized value of f in ZnO: graphene nanofiber was reconfirmed using UV-vis spectroscopy. The experiments were performed on the fiber optic probe fabricated with Ag/ZnO: graphene layer and optimized parameters for in-situ detection of nicotine. The interaction of nicotine with ZnO: graphene nanostructures alters the dielectric function of ZnO: graphene nanostructure which is manifested in terms of shift in resonance wavelength. From the sensing signal, the performance parameters were measured including sensitivity, limit of detection (LOD), limit of quantification (LOQ), stability, repeatability and selectivity. The real sample prepared using cigarette tobacco leaves and analyzed using the fabricated sensor makes it suitable for practical applications. The achieved values of LOD and LOQ are found to be unrivalled in comparison to the reported ones. The sensor possesses additional advantages such as, immunity to electromagnetic interference, low cost, capability of online monitoring, remote sensing. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of glyphosate and aminomethylphosphonic acid in leaves from Coffea arabica using high performance liquid chromatography with quadrupole mass spectrometry detection.

PubMed

Schrübbers, Lars C; Masís-Mora, Mario; Rojas, Elizabeth Carazo; Valverde, Bernal E; Christensen, Jan H; Cedergreen, Nina

2016-01-01

Glyphosate is a commonly applied herbicide in coffee plantations. Because of its non-selective mode of action it can damage the crop exposed through spray drift. Therefore, it is of interest to study glyphosate fate in coffee plants. The aim of this study was to develop an analytical method for accurate and precise quantification of glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) at trace levels in coffee leaves using liquid chromatography with single-quadrupole mass spectrometry detection. The method is based on a two-step solid phase extraction (SPE) with an intermediate derivatization reaction using 9-fluorenylmethylchloroformate (FMOC). An isotope dilution method was used to account for matrix effects and to enhance the confidence in analyte identification. The limit of quantification (LOQ) for glyphosate and AMPA in coffee leaves was 41 and 111 μg kg(-1) dry weight, respectively. For the method optimization a design of experiments (DOE) approach was used. The sample clean-up procedure can be simplified for the analysis of less challenging matrices, for laboratories having a tandem mass spectrometry detector and for cases in which quantification limits above 0.1 mg kg(-1) are acceptable, which is often the case for glyphosate. The method is robust, possesses high identification confidence, while being suitable for most commercial and academic laboratories. All leaf samples from five coffee fields analyzed (n=21) contained glyphosate, while AMPA was absent. The simplified clean-up procedure was successfully validated for coffee leaves, rice, black beans and river water. Copyright © 2015 Elsevier B.V. All rights reserved.

Measurements of airborne methylene diphenyl diisocyanate (MDI) concentration in the U.S. workplace.

PubMed

Booth, Karroll; Cummings, Barbara; Karoly, William J; Mullins, Sharon; Robert, William P; Spence, Mark; Lichtenberg, Fran W; Banta, J

2009-04-01

This article summarizes a large body of industry air sampling data (8134 samples) in which airborne MDI concentrations were measured in a wide variety of manufacturing processes that use either polymeric MDI (PMDI) or monomeric (pure) MDI. Data were collected during the period 1984 through 1999. A total of 606 surveys were conducted for 251 companies at 317 facilities. The database includes 3583 personal (breathing zone) samples and 4551 area samples. Data demonstrate that workplace airborne MDI concentrations are extremely low in a majority of the manufacturing operations. Most (74.6%) of the airborne MDI concentrations measured in the personal samples were nondetectable, i.e., below the limits of quantification (LOQs). A variety of validated industrial hygiene sampling/analytical methods were used for data collection; most are modifications of OSHA Method 47. The LOQs for these methods ranged from 0.1-0.5 microg/sample. The very low vapor pressures of both monomeric MDI and PMDI largely explain the low airborne concentrations found in most operations. However, processes or applications in which the chemical is sprayed or heated may result in higher airborne concentrations and higher exposure potentials if appropriate control measures are not implemented. Data presented in this article will be a useful reference for employers in helping them to manage their health and safety program as it relates to respiratory protection during MDI/PMDI applications.

Ultraperformance liquid chromatography-tandem mass spectrometry method for biomonitoring cooked meat carcinogens and their metabolites in human urine.

PubMed

Gu, Dan; Raymundo, Melissa M; Kadlubar, Fred F; Turesky, Robert J

2011-02-01

The cooked meat carcinogens 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), and their principal metabolites produced by cytochrome P450 and/or uridine diphosphate glucuronosyl transferases were simultaneously measured at the parts per trillion level in urine of omnivores, by ultraperformance liquid chromatography (UPLC) with a Michrom Advance CaptiveSpray source and a triple stage quadrupole mass spectrometer. Quantitation was performed in the selected reaction monitoring mode. The UPLC method is much more rapid and sensitive than our earlier capillary HPLC method: the duty cycle of the UPLC method is 19 min compared to 57 min for capillary HPLC. The performance of the UPLC assay was evaluated with urine samples from three subjects over 4 different days. The intraday and interday precisions of the estimates of PhIP, MeIQx, and their metabolites, reported as the coefficients of variation, were ≤10%. The limit of quantification (LOQ) values for PhIP and MeIQx were about 5 pg/mL, whereas the LOQ values of their metabolites ranged from 10 to 40 pg/mL. Furthermore, the identities of the analytes were corroborated by acquisition of full scan product ion spectra, employing between 0.5 and 5 pg of analyte for assay.

Optimization and validation of high-performance liquid chromatography method for analyzing 25-desacetyl rifampicin in human urine

NASA Astrophysics Data System (ADS)

Lily; Laila, L.; Prasetyo, B. E.

2018-03-01

A selective, reproducibility, effective, sensitive, simple and fast High-Performance Liquid Chromatography (HPLC) was developed, optimized and validated to analyze 25-Desacetyl Rifampicin (25-DR) in human urine which is from tuberculosis patient. The separation was performed by HPLC Agilent Technologies with column Agilent Eclipse XDB- Ci8 and amobile phase of 65:35 v/v methanol: 0.01 M sodium phosphate buffer pH 5.2, at 254 nm and flow rate of 0.8ml/min. The mean retention time was 3.016minutes. The method was linear from 2–10μg/ml 25-DR with a correlation coefficient of 0.9978. Standard deviation, relative standard deviation and coefficient variation of 2, 6, 10μg/ml 25-DR were 0-0.0829, 03.1752, 0-0.0317%, respectively. The recovery of 5, 7, 9μg/ml25-DR was 80.8661, 91.3480 and 111.1457%, respectively. Limits of detection (LoD) and quantification (LoQ) were 0.51 and 1.7μg/ml, respectively. The method has fulfilled the validity guidelines of the International Conference on Harmonization (ICH) bioanalytical method which includes parameters of specificity, linearity, precision, accuracy, LoD, and LoQ. The developed method is suitable for pharmacokinetic analysis of various concentrations of 25-DR in human urine.

Comparison of UPLC and HPLC methods for determination of vitamin C.

PubMed

Klimczak, Inga; Gliszczyńska-Świgło, Anna

2015-05-15

Ultra performance liquid chromatography (UPLC) and high-performance liquid chromatography (HPLC) methods for determination of ascorbic acid (AA) and total AA (TAA) contents (as the sum of AA and dehydroascorbic acid (DHAA) after its reduction to AA) in fruit beverages and in pharmaceutical preparations were compared. Both methods are rapid: total time of analysis was 15 and 6 min for HPLC and UPLC methods, respectively. The methods were validated in terms of linearity, instrument precision, limits of detection (LOD) and quantification (LOQ), accuracy and recovery. Intra- and inter-day instrument precisions for fruit juices, expressed as RSD, were 2.2% and 2.4% for HPLC, respectively, and 1.7% and 1.9% for UPLC, respectively. For vitamin C tablets, inter- and intra-day precisions were 0.4% and 0.5%, respectively (HPLC), and 0.5% and 0.3%, respectively (UPLC). Both methods were sensitive: LOD was 0.049 μg/mL for HPLC and 0.024 μg/mL for UPLC while LOQs were 0.149 and 0.073 μg/mL for HPLC and UPLC, respectively. These methods could be useful in the routine qualitative and quantitative analysis of AA or TAA in pharmaceutical preparations or fruit beverages. However, UPLC method is more sensitive, faster and consumes less eluent. Copyright © 2014 Elsevier Ltd. All rights reserved.

Occurrence of glyphosate and AMPA residues in soy-based infant formula sold in Brazil.

PubMed

Rodrigues, Nadia Regina; de Souza, Ana Paula Ferreira

2018-04-01

Glyphosate is an herbicide widely used in the world, being applied in several crops, among them soybeans. Recently, glyphosate and its metabolite aminomethylphosphonic acid (AMPA) have been identified as possible contributors to the emergence of various diseases such as autism, Parkinson's and Alzheimer's diseases, as well as cancer. The child population-consuming cereal-based foods is the most exposed to the effects of pesticides because of their developmental phase and they have a higher food intake per kilogram of body weight than adults. The presence of glyphosate and AMPA residues in soy-based infant formulas was evaluated during the years 2012-2017, totalising 105 analyses carried out on 10 commercial brands from different batches. Glyphosate and AMPA were determined by liquid chromatography with fluorescence detection after derivatisation reaction. The method was validated and showed accuracy and precision with a limit of quantification (LOQ) of 0.02 mg kg -1 . Among those samples that contained levels above the LOQ, the variation of glyphosate residues was from 0.03 mg kg -1 to 1.08 mg kg -1 and for AMPA residues was from 0.02 mg kg -1 to 0.17 mg kg -1 . This is the first scientific communication about glyphosate and AMPA contamination in soy-based infant formula in Brazil, The study was conducted under good laboratory practice (GLP) and supported by good scientific practice.

Dissipation kinetics of spinosad on cauliflower (Brassica oleracea var. botrytis. L.) under subtropical conditions of Punjab, India.

PubMed

Mandal, Kousik; Jyot, Gagan; Singh, Balwinder

2009-12-01

Residues of spinosad were estimated in cauliflower curds using high performance liquid chromatography (HPLC) and confirmed by high performance thin layer chromatography (HPTLC). Following three application of spinosad (Success 2.5 SC) at 15 and 30 g a.i. ha−1, the average initial deposits of spinosad were observed to be 0.57 and 1.34 mg kg−1, respectively. These residues dissipated below the limit of quantification (LOQ) of 0.02 mg kg−1 after 10 days at both the dosages. The half-life values (T 1/2) of spinosad were worked out to be 1.20 and 1.58 days, respectively, at recommended and double the recommended dosages. Thus, a waiting period of 6 days is suggested for the safe consumption of spinosad treated cauliflower.

A fast method for the determination of lead in honey samples using stabilizer-free silver nanoparticles

NASA Astrophysics Data System (ADS)

Bittar, Dayana Borges; Catelani, Tiago Augusto; Pezza, Leonardo; Pezza, Helena Redigolo

2018-01-01

A sensitive, rapid and robust method based on the use of stabilizer-free silver nanoparticles was developed for lead detection in honey. Silver nanoparticles were synthesized without the presence of any stabilizers using silver nitrate and sodium borohydride as precursors where the latter was applied as reducing agent. The optimization of the experimental variables (AgNO3 and NaBH4) for the formation of the nanoparticles was carried out using varying volumes of these solutions. Spectrophotometric measurements at 393 nm showed a linear working range between 0.0500 and 0.167 mg L- 1 lead (R = 0.994), with limits of detection (LOD) and quantification (LOQ) of 0.0135 and 0.0451 mg L- 1, respectively. The proposed method proved to be a significantly sensitive mechanism for lead detection in honey samples.

Determination and identification of malathion, ethion and dichlorovos using ion mobility spectrometry.

PubMed

Jafari, Mohammad T

2006-07-15

Positive ion mobility spectra of different organophosphorus pesticides such as malathion (s-(1,2-dicarb-ethoxyethyl) o,o-dimethyl dithiophosphate), ethion (o,o,o',o'-tetraethyl s,s'-methylene bis(phosphorodithioate)) and dichlorovos (2,2-dichlorovinyl dimethyl phosphate) have been studied in air at ambient pressure using ion mobility spectrometry method with (63)Ni ionization source. The limits of quantification (LOQs) were 1.0 x 10(-9), 1.0 x 10(-9) and 5.0 x 10(-9)g for malathion, ethion and dichlorovos, respectively. The working range of these compounds was about three orders of magnitude and the relative standard deviation (R.S.D.) of repeatability at the 5 microg ml(-1) level were all below 15%. Furthermore, in this study, the influences of IMS cell temperature on the ion mobility spectra of these compounds were investigated.

Determination of formaldehyde in Romanian cosmetic products using coupled GC/MS system after SPME extraction

NASA Astrophysics Data System (ADS)

Feher, I.; Schmutzer, G.; Voica, C.; Moldovan, Z.

2013-11-01

In this study we have made a quick review of some Romanian cosmetic products (shampoo, conditioner, face wash) in order to determine the formaldehyde content as well as other substances called "formaldehyde releasers". The process was performed based on solid-phase microextraction (SPME) followed by gas chromatography/mass spectrometry technique. Prior to SPME extraction we used a derivation step of formaldehyde using pentafluorophenyl hydrazine. The obtained product was adsorbed on SPME devices, then injected and desorbed into the GC/MS injection port. The concentration of formaldehyde (as derived compound) was calculated using calibration curve, having a regression coefficient of 0.9938. The performance parameters of the method were calculated using samples of standard concentration. The method proved to be sensitive, having a quantification limit (LOQ) of 0.15 μg/g.

[Simultaneous determination of delta-9-tetrahydrocannabinol cannabidiol and cannabinol in edible oil using ultra performance liquid chromatography-tandem mass spectrometry].

PubMed

Zhang, Aizhi; Wang, Quanlin; Mo, Shijie

2010-11-01

A method for the simultaneous determination of delta-9-tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN) in edible oil was developed using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The target compounds were extracted with methanol, purified by an LC-Alumina-N solid phase extraction cartridge, separated and detected by the UPLC-MS/MS. Quantitative analysis was corrected by an isotope internal standard method using delta-9-THC-D3 as internal standard. Average recoveries for the target compounds varied from 68.0% to 101.6% with the relative standard deviations ranging from 7.0% to 20.1% at three spiked levels. The limits of detection (LOD) of the method were from 0.06-0.17 microg/kg and the limits of quantification (LOQ) were in the range of 0.20-0.52 microg/kg. The results showed that the method is able to meet the requirements for the simultaneous determination of THC, CBD and CBN in edible oil.

On-matrix derivatization extraction of chemical weapons convention relevant alcohols from soil.

PubMed

Chinthakindi, Sridhar; Purohit, Ajay; Singh, Varoon; Dubey, D K; Pardasani, Deepak

2013-10-11

Present study deals with the on-matrix derivatization-extraction of aminoalcohols and thiodiglycols, which are important precursors and/or degradation products of VX analogues and vesicants class of chemical warfare agents (CWAs). The method involved hexamethyldisilazane (HMDS) mediated in situ silylation of analytes on the soil. Subsequent extraction and gas chromatography-mass spectrometry analysis of derivatized analytes offered better recoveries in comparison to the procedure recommended by the Organization for the Prohibition of Chemical Weapons (OPCW). Various experimental conditions such as extraction solvent, reagent and catalyst amount, reaction time and temperature were optimized. Best recoveries of analytes ranging from 45% to 103% were obtained with DCM solvent containing 5%, v/v HMDS and 0.01%, w/v iodine as catalyst. The limits of detection (LOD) and limit of quantification (LOQ) with selected analytes ranged from 8 to 277 and 21 to 665ngmL(-1), respectively, in selected ion monitoring mode. Copyright © 2013 Elsevier B.V. All rights reserved.

Simplified RP-HPLC method for multi-residue analysis of abamectin, emamectin benzoate and ivermectin in rice.

PubMed

Xie, Xianchuan; Gong, Shu; Wang, Xiaorong; Wu, Yinxing; Zhao, Li

2011-01-01

A rapid, reliable and sensitive reverse-phase high-performance liquid chromatography method with fluorescence detection (RP-FLD-HPLC) was developed and validated for simultaneous analysis of the abamectin (ABA), emamectin (EMA) benzoate and ivermectin (IVM) residues in rice. After extraction with acetonitrile/water (2 : 1) with sonication, the avermectin (AVMs) residues were directly derivatised by N-methylimidazole (N-NMIM) and trifluoroacetic anhydride (TFAA) and then analysed on RP-FLD-HPLC. A good linear relationship (r(2 )> 0.99) was obtained for three AVMs ranging from 0.01 to 5 microg ml(-1), i.e. 0.01-5.0 microg g(-1) in rice matrix. The limit of detection (LOD) and the limit of quantification (LOQ) were between 0.001 and 0.002 microg g(-1) and between 0.004 and 0.006 microg g(-1), respectively. Recoveries were from 81.9% to 105.4% and precision less than 12.4%. The proposed method was successfully applied to routine analysis of the AVMs residues in rice.

Development of a rapid, simple and sensitive HPLC-FLD method for determination of rhodamine B in chili-containing products.

PubMed

Qi, Ping; Lin, Zhihao; Li, Jiaxu; Wang, ChengLong; Meng, WeiWei; Hong, Hong; Zhang, Xuewu

2014-12-01

In this work, a simple, rapid and sensitive analytical method for the determination of rhodamine B in chili-containing foodstuffs is described. The dye is extracted from samples with methanol and analysed without further cleanup procedure by high-performance liquid chromatography (HPLC) coupled to fluorescence detection (FLD). The influence of matrix fluorescent compounds (capsaicin and dihydrocapsaicin) on the analysis was overcome by the optimisation of mobile-phase composition. The limit of determination (LOD) and limit of quantification (LOQ) were 3.7 and 10 μg/kg, respectively. Validation data show a good repeatability and within-lab reproducibility with relative standard deviations <10%. The overall recoveries are in the range of 98-103% in chili powder and in the range of 87-100% in chili oil depending on the concentration of rhodamine B in foodstuffs. This method is suitable for the routine analysis of rhodamine B due to its sensitivity, simplicity, reasonable time and cost. Copyright © 2014 Elsevier Ltd. All rights reserved.

Precursor ion scan driven fast untargeted screening and semi-determination of caffeoylquinic acid derivatives in Cynara scolymus L.

PubMed

Shen, Qing; Lu, Yanbin; Dai, Zhiyuan; Cheung, Hon-Yeung

2015-01-01

A precursor ion scan (PIS) technique based strategy was developed for rapid screening and semi-determination of caffeoylquinic acid derivatives (CADs) in artichoke (Cynara scolymus L.) using ultra-performance liquid chromatography (UPLC) coupled with tandem mass spectrometry. 1,5-Dicaffeoylquinic acid and 5-caffeoylquinic acid were used for studying the fragmentation behaviour of two classes of CADs, setting m/z 191 as a diagnostic moiety. When it was applied to artichoke sample, ten CADs were detected and elucidated in a single PIS run. Furthermore, method validation was implemented including: specificity (no interference), linearity (≥0.9993), limit of detection (LOD<0.12 ng mL(-1)) and limit of quantification (LOQ<0.25 ng mL(-1)), precision (RSD≤3.6), recovery (91.4-95.9%) and stability (at least 12 h). This approach was proven to be a powerful, selective and sensitive tool for rapid screening and semi-determination of untargeted components in natural products. Copyright © 2014 Elsevier Ltd. All rights reserved.

Solid-phase extraction of iridium from soil and water samples by using activated carbon cloth prior to its spectrophotometric determination.

PubMed

Ozkantar, Nebiye; Yilmaz, Erkan; Soylak, Mustafa; Tuzen, Mustafa

2015-08-01

A solid-phase extraction method for separation and preconcentration of Ir(IV) ion by using activated carbon cloth (ACC) has been presented. Ir(IV) as their 1-(2-pyridylazo) 2-naphtol (PAN) chelate was adsorbed on ACC at pH 2.0 and was eluted from ACC with acidic dimethylformamide (DMF). The Ir(IV) concentration was determined at 536 nm as Ir(IV)-PAN complex by using UV-vis spectrophotometer. The analytical parameters including pH, sample and eluent flow rates, amount of PAN, eluent type, concentration, and sample volume were optimized. The effects of foreign ions on the recoveries of iridium were also investigated. The preconcentration factor was calculated as 60. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were found as 0.039 and 0.129 μg L(-1), respectively. The method was applied to soil and water samples for iridium determination.

A rapid and simple determination of caffeine in teas, coffees and eight beverages.

PubMed

Sereshti, Hassan; Samadi, Soheila

2014-09-01

Caffeine was extracted and preconcentrated by the simple, fast and green method of dispersive liquid-liquid microextraction (DLLME) and analysed by gas chromatography-nitrogen phosphorus detection (GC-NPD). The influence of main parameters affecting the extraction efficiency investigated and optimised. Under the optimal conditions, the method was successfully applied to determination of caffeine in different real samples including five types of tea (green, black, white, oolong teas and tea bag), two kinds of coffee (Nescafe coffee and coffee), and eight beverages (regular Coca Cola, Coca Cola zero, regular Pepsi, Pepsi max, Sprite, 7up, Red Bull and Hype).The limit of detection (LOD) and limit of quantification (LOQ) were 0.02 and 0.05 μg mL(-1), respectively. Linear dynamic range (LDR) was 0.05-500 μg mL(-1) and determination coefficient (R(2)) was 0.9990. The relative standard deviation (RSD) was 3.2% (n=5, C=1 μg mL(-1)). Copyright © 2014 Elsevier Ltd. All rights reserved.

Micro-solid-phase extraction (µ-SPE) of organophosphorous pesticides from wheat followed by LC-MS/MS determination.

PubMed

Della Pelle, Flavio; Di Crescenzo, Maria Chiara; Sergi, Manuel; Montesano, Camilla; Di Ottavio, Francesca; Scarpone, Rossana; Scortichini, Giampiero; Compagnone, Dario

2016-01-01

A rapid, selective and effective method of extraction, clean-up and concentration of organophosphorous pesticides from wheat followed by electrospray (ESI) LC-MS/MS analysis was developed. The μ-SPE (micro-solid-phase extraction) procedure resulted in good analytical performance and reduced at the same time matrix effects, analysis time and solvent consumption. Limits of detection (LODs) and quantification (LOQs) were in the range of 0.3-10 and 1-30 μg kg(-1), respectively, with good reproducibility (RSD ≤ 13.8) and recoveries between 75% and 109%. Coefficients of determination (r(2)) were greater than 0.996 for the studied pesticides. Despite the reduced sorbent bed mass of μ-SPE tips (4.2 mg), the analytical data showed that no saturation phenomena occurs in the tested range of concentration both for single compounds and mixtures. Several real samples were analysed and the concentrations of the selected pesticides were found to be below the respective maximum residue limit (MRLs).

Dissipation and residue of myclobutanil in lychee.

PubMed

Liu, Yanping; Sun, Haibin; Liu, Fengmao; Wang, Siwei

2012-06-01

The dissipation and residue of myclobutanil in lychee under field conditions were studied. To determine myclobutanil residue in samples, an analytical method with a florisil column clean-up and detected by gas chromatography-electron capture detector (GC-ECD) was developed. Recoveries were found in the range of 83.24 %-89.00 % with relative standard deviations of 2.67 %-9.88 %. This method was successfully applied to analyze the dissipation and residue of myclobutanil in lychee in Guangdong and Guangxi Province, China. The half lives in lychee were from 2.2 to 3.4 days. The residues of myclobutanil in lychee flesh were all below the limit of quantification (LOQ) value (0.01 mg/kg), and most of the residues were concentrated in the peel. The terminal residues of myclobutanil were all bellow the maximum residue limit (MRL) value set by European Union (EU) (0.02 mg/kg). Hence it was safe for the use of this pesticide and the results also could give a reference for MRL setting of myclobutanil in lychee in China.

Evaluation of the Presence and Levels of Enrofloxacin, Ciprofloxacin, Sulfaquinoxaline and Oxytetracycline in Broiler Chickens after Drug Administration

PubMed Central

da Silva, Guilherme Resende; Lanza, Isabela Pereira; Ribeiro, Ana Cláudia dos Santos Rossi; Lana, Ângela Maria Quintão; Lara, Leonardo José Camargos

2016-01-01

The depletion times of enrofloxacin and its metabolite ciprofloxacin as well as sulfaquinoxaline and oxytetracycline were evaluated in broiler chickens that had been subjected to pharmacological treatment. The presence and residue levels of these drugs in muscle tissue were evaluated using an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method that was validated in this work. The results showed the presence of all antimicrobial residues; however, the presence of residues at concentrations higher than the drugs’ maximum residue limit (MRL) of 100 μg kg-1 was found only during the treatment period for oxytetracycline and until two days after discontinuation of the medication for enrofloxacin, ciprofloxacin and sulfaquinoxaline. It was concluded that the residues of all antimicrobials were rapidly metabolized from the broiler muscles; after four days of withdrawal, the levels were lower than the limit of quantification (LOQ) of the method for the studied analytes. PMID:27846314

Evaluation of the Presence and Levels of Enrofloxacin, Ciprofloxacin, Sulfaquinoxaline and Oxytetracycline in Broiler Chickens after Drug Administration.

PubMed

de Assis, Débora Cristina Sampaio; da Silva, Guilherme Resende; Lanza, Isabela Pereira; Ribeiro, Ana Cláudia Dos Santos Rossi; Lana, Ângela Maria Quintão; Lara, Leonardo José Camargos; de Figueiredo, Tadeu Chaves; Cançado, Silvana de Vasconcelos

2016-01-01

The depletion times of enrofloxacin and its metabolite ciprofloxacin as well as sulfaquinoxaline and oxytetracycline were evaluated in broiler chickens that had been subjected to pharmacological treatment. The presence and residue levels of these drugs in muscle tissue were evaluated using an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method that was validated in this work. The results showed the presence of all antimicrobial residues; however, the presence of residues at concentrations higher than the drugs' maximum residue limit (MRL) of 100 μg kg-1 was found only during the treatment period for oxytetracycline and until two days after discontinuation of the medication for enrofloxacin, ciprofloxacin and sulfaquinoxaline. It was concluded that the residues of all antimicrobials were rapidly metabolized from the broiler muscles; after four days of withdrawal, the levels were lower than the limit of quantification (LOQ) of the method for the studied analytes.

Gas chromatography with flame photometric detection of 31 organophosphorus pesticide residues in Alpinia oxyphylla dried fruits.

PubMed

Zhao, Xiangsheng; Kong, Weijun; Wei, Jianhe; Yang, Meihua

2014-11-01

A simple, rapid and effective gas chromatography-flame photometric detection method was established for simultaneous multi-component determination of 31 organophosphorus pesticides (OPPs) residues in Alpinia oxyphylla, which is widely consumed as a traditional medicine and food in China. Sample preparation was completed in a single step without any clean-up procedure. All pesticides expressed good linear relationships between 0.004 and 1.0 μg/mL with correlation coefficients higher than 0.9973. The method gave satisfactory recoveries for most pesticides. The limits of detection varied from 1 to 10 ng/mL, and the limits of quantification (LOQs) were between 4 and 30 ng/mL. The proposed method was successfully applied to 55 commercial samples purchased from five different areas. Five pesticide residues were detected in four (7.27%) samples. The positive samples were confirmed by gas chromatography with tandem mass spectrometry (GC-MS/MS). Copyright © 2014 Elsevier Ltd. All rights reserved.

Simple and Fast Extraction-Coupled UPLC-MS/MS Method for the Determination of Mequindox and Its Major Metabolites in Food Animal Tissues.

PubMed

You, Yanli; Song, Liting; Li, Yanshen; Wu, Yongtao; Xin, Mao

2016-03-23

This research described a sensitive and rapid UPLC-MS/MS method for the determination of mequindox and its six major metabolites in chicken muscle, chicken liver, swine muscle, and swine liver. Among the metabolites, carbonyl reduction-1,4-bisdesoxy-mequindox is novel. Target analytes could be extracted by ethyl acetate without any acidolysis or enzymolysis steps. After purification by a Bond Elut C18 cartridge, analysis was carried out by UPLC-MS/MS using positive ion multiple reaction monitoring (MRM) mode. Validation was performed in spiked samples, and mean recoveries ranged from 64.3 to 114.4%, with intraday and interday variations of less than 14.7 and 19.2%, respectively. The limit of detection (LOD) was <1.0 μg kg(-1), whereas the limit of quantification (LOQ) was <4.0 μg kg(-1). This procedure will help monitor mequindox residues in animal-derived food, and it will also facilitate further pharmacokinetics of mequindox.

Identification of multi-insecticide residues using GC-NPD and the degradation kinetics of chlorpyrifos in sweet corn and soils.

PubMed

Wang, Peidan; Rashid, Muhammad; Liu, Jie; Hu, Meiying; Zhong, Guohua

2016-12-01

Because more than one insecticide is applied to crops to protect plants from pests, an analytical multi-residue determination method was developed using gas chromatography with a nitrogen phosphorus detector (GC-NPD). The retention time for 12 insecticides was 3.7-27.7min. Under the selected conditions, the limits of detection (LOD) and quantification (LOQ) were below the maximum residue limits (MRLs) and in the range of 0.00315-0.05μgmL(-1) and 0.01-0.165μgmL(-1), respectively. Using GC-NPD, we investigated the dissipation dynamics and final residual levels of chlorpyrifos in sweet corn and soil and determined that the half-lives was 4-7days, that is, that chlorpyrifos is safe to use on sweet corn with a pre-harvest interval of 16-22days before harvest. These results provide new insights into chlorpyrifos degradation in plants and its environmental behavior. Copyright © 2016. Published by Elsevier Ltd.

A comparison of the extraction procedures and quantification methods for the chromatographic determination of polycyclic aromatic hydrocarbons in charcoal grilled meat and fish.

PubMed

Viegas, O; Novo, P; Pinho, O; Ferreira, I M P L V O

2012-01-15

A method for analysis of 15 PAHs in charcoal-grilled meat/fish was established by high performance liquid chromatography and fluorescence detection. Gradient elution was performed with methanol/water/ethyl acetate. Maxima excitation and emission wavelengths were selected for each PAH. Retention times were very stable with coefficients of variation below 0.24% within analytical day and below 0.60% across analytical days. Two different methods of cleanup and pre-concentration steps were compared. Solvent extraction assisted by sonication carried out with n-hexane on 2g of lyophilized meat or 1g of lyophilized fish allowed to obtain high sensitivity, reproducibility and better extraction efficiency. Limits of quantification (LOQs, s/n=10) were lower than 0.01ng/g of meat wet weight and lower than 0.02ng/g of fish wet weight for all PAHs (except for Na, Fl and IP that were lower than 0.1ng/g). Two different quantification methods were compared. Standard addition method compensated PAHs losses due to incomplete extraction and it is recommended for analyses of grilled meat and fish samples that usually contain very low amounts of the eight high molecular weight PAHs (BaA, Ch, BbF, BkF, BaP, IP, BgP, DhA). Copyright © 2011 Elsevier B.V. All rights reserved.

Quantitative analysis of pyoluteorin in anti-fungal fermentation liquor of Pseudomonas species by capillary zone electrophoresis with UV-vis detector.

PubMed

Wang, Qiu-Ling; Zhang, Xue-Hong; Fan, Liu-Yin; Zhang, Wei; Xu, Yu-Qian; Hu, Hong-Bo; Cao, Cheng-Xi

2005-11-05

This paper investigated potential utility of capillary zone electrophoresis (CZE) for very succinct but robust quantitative analysis of pyoluteorin (Plt) in anti-fungal fermentation liquor of Pseudomonas species. The experimental conditions for the separation and quantification of Plt were optimized at first. The optimized conditions are: 80 mmol/L pH 8.40 Gly-NaOH buffer, 51 cm total length (42 cm effective) and 75 microm I.D. capillary, 230 nm wavelength, 25 kV, 13 mbar 10s pressure sample injection and 24 degrees C air-cooling. Under the optimized conditions, the migration times of Plt and the internal standard phenobarbital are 2.09 and 2.49 min, respectively, the linear response of Plt concentration ranges from 5.0 to 1000 microg/mL with high correlation coefficient (r=0.99977, n=9), the limits of detection (LOD) and quantification (LOQ) for Plt are 0.66 and 2.2 microg/mL, the precision values (expressed as R.S.D.) of intra- and inter-day are 1.19-1.94% and 1.55-6.21%, respectively, the recoveries of Plt at three concentration levels of 750, 250 and 50 microg/mL range from 90.31% to 97.85% and to 98.96%, respectively. The developed method can be well used for the quantification of Plt in the fermentation liquor.

Quantification of Hemoglobin and White Blood Cell DNA Adducts of the Tobacco Carcinogens 2-Amino-9H-pyrido[2,3-b]indole and 4-Aminobiphenyl Formed in Humans by Nanoflow Liquid Chromatography/Ion Trap Multistage Mass Spectrometry.

PubMed

Cai, Tingting; Bellamri, Medjda; Ming, Xun; Koh, Woon-Puay; Yu, Mimi C; Turesky, Robert J

2017-06-19

Aromatic amines covalently bound to hemoglobin (Hb) as sulfinamide adducts at the cysteine 93 residue of the Hb β chain have served as biomarkers to assess exposure to this class of human carcinogens for the past 30 years. In this study, we report that 2-amino-9H-pyrido[2,3-b]indole (AαC), an abundant carcinogenic heterocyclic aromatic amine formed in tobacco smoke and charred cooked meats, also reacts with Hb to form a sulfinamide adduct. A novel nanoflow liquid chromatography/ion trap multistage mass spectrometry (nanoLC-IT/MS 3 ) method was established to assess exposure to AαC and the tobacco-associated bladder carcinogen 4-aminobiphenyl (4-ABP) through their Hb sulfinamide adducts. Following mild acid hydrolysis of Hb in vitro, the liberated AαC and 4-ABP were derivatized with acetic anhydride to form the N-acetylated amines, which were measured by nanoLC-IT/MS 3 . The limits of quantification (LOQ) for AαC- and 4-ABP-Hb sulfinamide adducts were ≤7.1 pg/g Hb. In a pilot study, the mean level of Hb sulfinamide adducts of AαC and 4-ABP were, respectively, 3.4-fold and 4.8-fold higher in smokers (>20 cigarettes/day) than nonsmokers. In contrast, the major DNA adducts of 4-ABP, N-(2'-deoxyguanosin-8-yl)-4-aminobiphenyl, and AαC, N-(2'-deoxyguanosin-8-yl)-2-amino-9H-pyrido[2,3-b]indole, were below the LOQ (3 adducts per 10 9 bases) in white blood cell (WBC) DNA of smokers and nonsmokers. These findings reaffirm that tobacco smoke is a major source of exposure to AαC. Hb sulfinamide adducts are suitable biomarkers to biomonitor 4-ABP and AαC; however, neither carcinogen binds to DNA in WBC, even in heavy smokers, at levels sufficient for biomonitoring.

Development of a multiple-class analytical method based on the use of synthetic matrices for the simultaneous determination of commonly used commercial surfactants in wastewater by liquid chromatography-tandem mass spectrometry.

PubMed

Alexandre, Bergé; Barbara, Giroud; Laure, Wiest; Bruno, Domenjoud; Adriana, Gonzalez-Ospina; Emmanuelle, Vulliet

2016-06-10

Discharges of surfactants from wastewater treatment plants are often considered as the principal vector of pollution into the environment. The analysis of complex matrices, such as urban wastewater, suspended solids and biological sludge requires careful preparation of the sample to obtain a sensitive, selective and reproducible analysis. A simple, fast, effective and multi-residue method based on the SPE (water) and QuEChERS (solid matrices) approaches using synthetic matrices for validation and quantification, has been developed for the determination of 16 surfactants in wastewater, suspended solids and biological sludge. This work resulted in an innovative method that was validated to detect and assess several classes of surfactants such as quaternary ammonium compounds, betaïns, alkylphenols and their ethoxylated or sulfated derivatives in urban wastewater and solid matrices. The optimised extraction method exhibited recoveries comprised between 83% and 120% for all the tested compounds in the dissolved matrix and between 50% and 109% for particulate matrix. The limits of quantification of all compounds were comprised between 0.1 and 1.0μg/L for dissolved matrix and between 2 and 1000ng/g (dry weight) in particulate matrix. Linearity was assessed for all compounds within the [LOQ-250LOQ] range. Confidence intervals were also computed in real matrices with less than 15% margin of error for all studied surfactants. This work has confirmed, first and foremost, that surfactants are indeed highly concentrated in urban wastewater. As expected, linear alkylbenzene sulfonates were present at significant concentrations (up to 1-2mg/L). In addition, although biological processing results in significant removal of the total pollution, the residual concentrations at output of WWTP remain significant (up to 100μg/L). Copyright © 2016 Elsevier B.V. All rights reserved.

A novel fluorescence-based assay for the rapid detection and quantification of cellular deoxyribonucleoside triphosphates

PubMed Central

Wilson, Peter M.; LaBonte, Melissa J.; Russell, Jared; Louie, Stan; Ghobrial, Andrew A.; Ladner, Robert D.

2011-01-01

Current methods for measuring deoxyribonucleoside triphosphates (dNTPs) employ reagent and labor-intensive assays utilizing radioisotopes in DNA polymerase-based assays and/or chromatography-based approaches. We have developed a rapid and sensitive 96-well fluorescence-based assay to quantify cellular dNTPs utilizing a standard real-time PCR thermocycler. This assay relies on the principle that incorporation of a limiting dNTP is required for primer-extension and Taq polymerase-mediated 5–3′ exonuclease hydrolysis of a dual-quenched fluorophore-labeled probe resulting in fluorescence. The concentration of limiting dNTP is directly proportional to the fluorescence generated. The assay demonstrated excellent linearity (R2 > 0.99) and can be modified to detect between ∼0.5 and 100 pmol of dNTP. The limits of detection (LOD) and quantification (LOQ) for all dNTPs were defined as <0.77 and <1.3 pmol, respectively. The intra-assay and inter-assay variation coefficients were determined to be <4.6% and <10%, respectively with an accuracy of 100 ± 15% for all dNTPs. The assay quantified intracellular dNTPs with similar results obtained from a validated LC–MS/MS approach and successfully measured quantitative differences in dNTP pools in human cancer cells treated with inhibitors of thymidylate metabolism. This assay has important application in research that investigates the influence of pathological conditions or pharmacological agents on dNTP biosynthesis and regulation. PMID:21576234

A Fast and Validated Reversed-Phase HPLC Method for Simultaneous Determination of Simvastatin, Atorvastatin, Telmisartan and Irbesartan in Bulk Drugs and Tablet Formulations

PubMed Central

Alhazmi, Hassan A.; Alnami, Ahmed M.; Arishi, Mohammed A. A.; Alameer, Raad K.; Al Bratty, Mohammed; Rehman, Zia ur; Javed, Sadique A.; Arbab, Ismail A.

2017-01-01

The aim of this study was to develop and validate a fast and simple reversed-phase HPLC method for simultaneous determination of four cardiovascular agents—atorvastatin, simvastatin, telmisartan and irbesartan in bulk drugs and tablet oral dosage forms. The chromatographic separation was accomplished by using Symmetry C18 column (75 mm × 4.6 mm; 3.5 μ) with a mobile phase consisting of ammonium acetate buffer (10 mM; pH 4.0) and acetonitrile in a ratio 40:60 v/v. Flow rate was maintained at 1 mL/min up to 3.5 min, and then suddenly changed to 2 mL/min till the end of the run (7.5 min). The data was acquired using ultraviolet detector monitored at 220 nm. The method was validated for linearity, precision, accuracy and specificity. The developed method has shown excellent linearity (R2 > 0.999) over the concentration range of 1–16 µg/mL. The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.189–0.190 and 0.603–0.630 µg/mL, respectively. Inter-day and intra-day accuracy and precision data were recorded in the acceptable limits. The new method has successfully been applied for quantification of all four drugs in their tablet dosage forms with percent recovery within 100 ± 2%. PMID:29257120

Isocratic RP-HPLC method for rutin determination in solid oral dosage forms.

PubMed

Kuntić, Vesna; Pejić, Natasa; Ivković, Branka; Vujić, Zorica; Ilić, Katarina; Mićić, Svetlana; Vukojević, Vladana

2007-01-17

A rapid and sensitive assay for quantitative determination of rutin in oral dosage forms based on isocratic reversed phase high performance liquid chromatography (RP-HPLC) was developed and validated. Using a C(18) reverse-phase analytical column, the following conditions were chosen as optimal: mobile phase methanol-water 1:1 (v/v), pH 2.8 (adjusted with phosphoric acid), flow rate=1 mL min(-1) and temperature T=40.0 degrees C. Linearity was observed in the concentration range 8-120 microg mL(-1) with a correlation coefficient of 0.99982 and the limit of detection (LOD)=2.6 microg mL(-1), and limit of quantification (LOQ)=8.0 microg mL(-1). Intra- and inter-day precision were within acceptable limits. Robustness test indicated that the mobile phase composition and pH influence mainly the separation. The proposed method allowed direct determination of rutin in pharmaceutical dosage forms in the presence of excipients, but is not suitable for preparations where compounds structurally/chemically related to rutin may be present.

Application of Focused Ultrasound-Assisted Extraction for the Quantification of Persistent Organic Pollutions in Liver Tissue of Giant Toad (Rhinella marina).

PubMed

Flores-Ramírez, R; Espinosa-Reyes, G; Cilia-López, V G; González-Mille, D J; Rodríguez-Aguilar, M; Díaz de León-Martínez, L; Díaz-Barriga, F

2017-02-01

A simple and rapid focused ultrasound extraction method was developed for the determination of Persistent Organic Pollutants (POPs) in liver tissue obtained of giant toad (Rhinella marina) using a gas chromatography coupled to a mass detector with electron impact ionization. The performed method for POPs, was validated in fortified matrix, showing linearity from the LOQ up to 100 ng/mL; LODs and LOQs for each compound were between 1.7 and 4.8 and 3.5-7.5 ng/mL, respectively. Recovery rates were among 79%-116% for POPs determined. Finally, the method was applied in liver samples of giant toads found in a malarial area in Mexico. The sensitivity of the proposed method was good enough to ensure reliable determination of target analytes at concentration levels commonly found in this kind of samples.

Methyl angolensate changes in Khaya ivorensis after fungal infection.

PubMed

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

2009-12-01

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

Electrochemistry of moexipril: experimental and computational approach and voltammetric determination.

PubMed

Taşdemir, Hüdai I; Kiliç, E

2014-09-01

The electrochemistry of moexipril (MOE) was studied by electrochemical methods with theoretical calculations performed at B3LYP/6-31 + G (d)//AM1. Cyclic voltammetric studies were carried out based on a reversible and adsorption-controlled reduction peak at -1.35 V on a hanging mercury drop electrode (HMDE). Concurrently irreversible diffusion-controlled oxidation peak at 1.15 V on glassy carbon electrode (GCE) was also employed. Potential values are according to Ag/AgCI, (3.0 M KCI) and measurements were performed in Britton-Robinson buffer of pH 5.5. Tentative electrode mechanisms were proposed according to experimental results and ab-initio calculations. Square-wave adsorptive stripping voltammetric methods have been developed and validated for quantification of MOE in pharmaceutical preparations. Linear working range was established as 0.03-1.35 microM for HMDE and 0.2-20.0 microM for GCE. Limit of quantification (LOQ) was calculated to be 0.032 and 0.47 microM for HMDE and GCE, respectively. Methods were successfully applied to assay the drug in tablets by calibration and standard addition methods with good recoveries between 97.1% and 106.2% having relative standard deviation less than 10%.

Multiresidue analysis of 22 sulfonamides and their metabolites in animal tissues using quick, easy, cheap, effective, rugged, and safe extraction and high resolution mass spectrometry (hybrid linear ion trap-Orbitrap).

PubMed

Abdallah, H; Arnaudguilhem, C; Jaber, F; Lobinski, R

2014-08-15

A new high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) method was developed for a simultaneous multi-residue analysis of 22 sulfonamides (SAs) and their metabolites in edible animal (pig, beef, sheep and chicken) tissues. Sample preparation was optimized on the basis of the "QuEChERS" protocol. The analytes were identified using their LC retention times and accurate mass; the identification was further confirmed by multi-stage high mass accuracy (<5ppm) mass spectrometry. The performance of the method was evaluated according to the EU guidelines for the validation of screening methods for the analysis of veterinary drugs residues. Acceptable values were obtained for: linearity (R(2)<0.99), limit of detection (LOD, 3-26μg/kg), limit of quantification (LOQ, 11-88μg/kg), accuracy (recovery 88-112%), intra- and inter-day precision 1-14 and 1-17%, respectively, decision limit (CCα) and detection capability (CCβ) around the maximum residue limits (MRL) of SAs (100μg/kg). The method was validated by analysis of a reference material FAPAS-02188 "Pig kidney" with ǀ Z-scoreǀ<0.63. The method was applied to various matrices (kidney, liver, muscle) originated from pig, beef, sheep, and chicken) allowing the simultaneous quantification of target sulfonamides at concentration levels above the MRL/2 and the identification of untargeted compounds such as N(4)-acetyl metabolites using multi-stage high mass accuracy mass spectrometry. Copyright © 2014 Elsevier B.V. All rights reserved.

International collaborative study of the endogenous reference gene, sucrose phosphate synthase (SPS), used for qualitative and quantitative analysis of genetically modified rice.

PubMed

Jiang, Lingxi; Yang, Litao; Zhang, Haibo; Guo, Jinchao; Mazzara, Marco; Van den Eede, Guy; Zhang, Dabing

2009-05-13

One rice ( Oryza sativa ) gene, sucrose phosphate synthase (SPS), has been proven to be a suitable endogenous reference gene for genetically modified (GM) rice detection in a previous study. Herein are the reported results of an international collaborative ring trial for validation of the SPS gene as an endogenous reference gene and its optimized qualitative and quantitative polymerase chain reaction (PCR) systems. A total of 12 genetically modified organism (GMO) detection laboratories from seven countries participated in the ring trial and returned their results. The validated results confirmed the species specificity of the method through testing 10 plant genomic DNAs, low heterogeneity, and a stable single-copy number of the rice SPS gene among 7 indica varieties and 5 japonica varieties. The SPS qualitative PCR assay was validated with a limit of detection (LOD) of 0.1%, which corresponded to about 230 copies of haploid rice genomic DNA, while the limit of quantification (LOQ) for the quantitative PCR system was about 23 copies of haploid rice genomic DNA, with acceptable PCR efficiency and linearity. Furthermore, the bias between the test and true values of eight blind samples ranged from 5.22 to 26.53%. Thus, we believe that the SPS gene is suitable for use as an endogenous reference gene for the identification and quantification of GM rice and its derivates.

Quantification and characterization of alkaloids from roots of Rauwolfia serpentina using ultra-high performance liquid chromatography-photo diode array-mass spectrometry.

PubMed

Sagi, Satyanarayanaraju; Avula, Bharathi; Wang, Yan-Hong; Khan, Ikhlas A

2016-01-01

A new UHPLC-UV method has been developed for the simultaneous analysis of seven alkaloids [ajmaline (1), yohimbine (2), corynanthine (3), ajmalicine (4), serpentine (5), serpentinine (6), and reserpine (7)] from the root samples of Rauwolfia serpentina (L.) Benth. ex Kurz. The chromatographic separation was achieved using a reversed phase C18 column with a mobile phase of water and acetonitrile, both containing 0.05% formic acid. The seven compounds were completely separated within 8 min at a flow rate of 0.2 mL/min with a 2-μL injection volume. The method is validated for linearity, accuracy, repeatability, limits of detection (LOD), and limits of quantification (LOQ). Seven plant samples and 21 dietary supplements claiming to contain Rauwolfia roots were analyzed and content of total alkaloids (1-7) varied, namely, 1.57-12.1 mg/g dry plant material and 0.0-4.5 mg/day, respectively. The results indicated that commercial products are of variable quality. The developed analytical method is simple, economic, fast, and suitable for quality control analysis of Rauwolfia samples and commercial products. The UHPLC-QToF-mass spectrometry with electrospray ionization (ESI) interface method is described for the confirmation and characterization of alkaloids from plant samples. This method involved the detection of [M + H](+) or M(+) ions in the positive mode.

Multi-residue method for the determination of pesticides and pesticide metabolites in honeybees by liquid and gas chromatography coupled with tandem mass spectrometry--Honeybee poisoning incidents.

PubMed

Kiljanek, Tomasz; Niewiadowska, Alicja; Semeniuk, Stanisław; Gaweł, Marta; Borzęcka, Milena; Posyniak, Andrzej

2016-02-26

A method for the determination of 200 pesticides and pesticide metabolites in honeybee samples has been developed and validated. Almost 98% of compounds included in this method are approved to use within European Union, as active substances of plant protection products or veterinary medicinal products used by beekeepers to control mites Varroa destructor in hives. Many significant metabolites, like metabolites of imidacloprid, thiacloprid, fipronil, methiocarb and amitraz, are also possible to detect. The sample preparation was based on the buffered QuEChERS method. Samples of bees were extracted with acetonitrile containing 1% acetic acid and then subjected to clean-up by dispersive solid phase extraction (dSPE) using a new Z-Sep+ sorbent and PSA. The majority of pesticides, including neonicotionoids and their metabolites, were analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) but some of pesticides, especially pyrethroid insecticides, were analyzed by gas chromatography tandem mass spectrometry (GC-MS/MS). The procedure was validated according to the Guidance document SANCO/12571/2013 at four concentration levels: 1, 5, 10 and 100 ng/g bees and verified in the international proficiency test. The analysis of bee samples spiked at the limit of quantification (LOQ) showed about 98% mean recovery value (trueness) and 97% of analytes showed recovery in the required range of 70-120% and RSDr (precision) below 20%. Linearity and matrix effects were also established. The LOQs of pesticides were in the range of 1-100 ng/g. The developed method allows determination of insecticides at concentrations of 10 ng/g or less, except abamectin and tebufenozide. LOQ values are lower than the median lethal doses LD50 for bees. The method was used to investigate more than 70 honeybee poisoning incidents. Data about detected pesticides and their metabolites are included. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of cocoa products for ochratoxin A and aflatoxins.

PubMed

Turcotte, Anne-Marie; Scott, Peter M; Tague, Brett

2013-08-01

Eighty-five samples of cocoa products sampled in Canada were analysed for ochratoxin A (OTA) and aflatoxins in 2011-2012. Inclusion of the aflatoxins in this survey required additional method development. Chocolate was extracted with methanol-water plus NaCl, while for cocoa two successive extractions with methanol and methanol-water were made. Extracts were cleaned on an AflaOchra immunoaffinity column (IAC). Determination was by reversed phase high performance liquid chromatography (HPLC). Detection of the aflatoxins was with a post-column photochemical reactor and of OTA by fluorescence detection. Mean limits of quantification (LOQ) of chocolate and cocoa powders were 0.16 ng/g (OTA) and 0.07 ng/g (aflatoxin B1), respectively. Survey results showed that the incidences of OTA above the LOQ in natural cocoa were 15/15 (mean 1.17 ng/g), 20/21 for alkalized cocoa (mean 1.06 ng/g), 9/9 for baking chocolate (mean 0.49 ng/g), 20/20 for dark chocolate (mean 0.39 ng/g), 7/10 for milk chocolate (mean 0.19 ng/g), 5/5 for cocoa liquor (mean 0.43 ng/g), and 0/5 for cocoa butter. These results confirm our previous work with OTA. In the same samples, incidences of aflatoxin B1 above the LOQ were 14/15 for natural cocoa (mean 0.86 ng/g), 20/21 for alkalized cocoa (mean 0.37 ng/g), 7/9 for baking chocolate (mean 0.22 ng/g), 16/20 for dark chocolate (mean 0.19 ng/g), 7/10 for milk chocolate (mean 0.09 ng/g), 4/5 for cocoa liquor (mean 0.43 ng/g), and 0/5 for cocoa butter. Both aflatoxins and OTA were confirmed by HPLC-MS/MS when OTA or aflatoxin levels found were above 2 ng/g in cocoa.

A novel fast method for aqueous derivatization of THC, OH-THC and THC-COOH in human whole blood and urine samples for routine forensic analyses.

PubMed

Stefanelli, Fabio; Pesci, Federica Giorgia; Giusiani, Mario; Chericoni, Silvio

2018-04-01

A novel aqueous in situ derivatization procedure with propyl chloroformate (PCF) for the simultaneous, quantitative analysis of Δ 9 -tetrahydrocannabinol (THC), 11-hydroxy-Δ 9 -tetrahydrocannabinol (OH-THC) and 11-nor-Δ 9 -tetrahydrocannabinol-carboxylic acid (THC-COOH) in human blood and urine is proposed. Unlike current methods based on the silylating agent [N,O-bis(trimethylsilyl)trifluoroacetamide] added in an anhydrous environment, this new proposed method allows the addition of the derivatizing agent (propyl chloroformate, PCF) directly to the deproteinized blood and recovery of the derivatives by liquid-liquid extraction. This novel method can be also used for hydrolyzed urine samples. It is faster than the traditional method involving a derivatization with trimethyloxonium tetrafluoroborate. The analytes are separated, detected and quantified by gas chromatography-mass spectrometry in selected ion monitoring mode (SIM). The method was validated in terms of selectivity, capacity of identification, limits of detection (LOD) and quantification (LOQ), carryover, linearity, intra-assay precision, inter-assay precision and accuracy. The LOD and LOQ in hydrolyzed urine were 0.5 and 1.3 ng/mL for THC and 1.2 and 2.6 ng/mL for THC-COOH, respectively. In blood, the LOD and LOQ were 0.2 and 0.5 ng/mL for THC, 0.2 and 0.6 ng/mL for OH-THC, and 0.9 and 2.4 ng/mL for THC-COOH, respectively. This method was applied to 35 urine samples and 50 blood samples resulting to be equivalent to the previously used ones with the advantage of a simpler method and faster sample processing time. We believe that this method will be a more convenient option for the routine analysis of cannabinoids in toxicological and forensic laboratories. Copyright © 2017 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.

Enantioseparation and determination of the chiral fungicide furametpyr enantiomers in rice, soil, and water by high-performance liquid chromatography.

PubMed

Dong, Fengshou; Chen, Xiu; Xu, Jun; Liu, Xingang; Chen, Zenglong; Li, Yuanbo; Zhang, Hongjun; Zheng, Yongquan

2013-12-01

The chiral fungicide furametpyr is widely used in the rice field to control rice sheath blight; however, furametpyr enantiomers are treated as just one compound in traditional achiral analysis, which gives only partial information. An effective chiral analytical method was developed for the resolution and determination of the fungicide furametpyr enantiomers in rice, soil, and water samples. Furametpyr enantiomers were excellently separated and determined on a Chiralpak AD-H column with n-hexane/ethanol (90:10, v/v) as mobile phase at a flow rate of 0.8 mL min(-1) with UV detection at 220 nm. The resolution was up to 8.85. The first eluted enantiomer was (+)-furametpyr and the second eluted one was (-)-furametpyr. The effects of mobile-phase composition and column temperature on the enantioseparation were evaluated. The method was validated for linearity, repeatability, accuracy, limit of detection (LOD), and limit of quantification LOQ. LOD was 2.0 µg kg(-1) in water, 0.02 mg kg(-1) in soil, and 0.07 mg kg(-1) in rice with an LOQ of 6.7 µg kg(-1) in water, 0.07 mg kg(-1) in soil, and 0.23 mg kg(-1) in rice. The average recoveries of the pesticide in all matrices ranged from 73.1 to 101.8% for all fortification levels. The precision values associated with the analytical method, expressed as relative standard deviation (RSD) values, were below 14.0% in all matrices. The methodology was successfully applied for the enantioselective analysis of furametpyr enantiomers in real samples. © 2013 Wiley Periodicals, Inc.

Evaporative light scattering detector in normal-phase high-performance liquid chromatography determination of FAME oxidation products.

PubMed

Morales, Arturo; Marmesat, Susana; Dobarganes, M Carmen; Márquez-Ruiz, Gloria; Velasco, Joaquín

2012-09-07

The use of an ELS detector in NP-HPLC for quantitative analysis of oxidation products in FAME obtained from oils is evaluated in this study. The results obtained have shown that the ELS detector enables the quantitative determination of the hydroperoxides of oleic and linoleic acid methyl esters as a whole, and connected in series with a UV detector makes it possible to determine both groups of compounds by difference, providing useful complementary information. The limits of detection (LOD) and quantification (LOQ) found for hydroperoxides were respectively 2.5 and 5.7 μg mL⁻¹ and precision of quantitation expressed as coefficient of variation was lower than 10%. Due to a low sensitivity the ELS detector shows limitations to determine the low contents of secondary oxidation products in the direct analysis of FAME oxidized at low or moderate temperature. Analysis of FAME samples obtained either from high linoleic sunflower oil (HLSO) or high oleic sunflower oil (HOSO) and oxidized at 80 °C showed that only ketodienes formed from methyl linoleate can be determined in samples with relatively high oxidation, being the LOD and LOQ 0.2 and 0.4 mg/g FAME, respectively, at the analytical conditions applied. The ELS detector also enabled the determination of methyl cis-9,10-epoxystearate and methyl trans-9,10-epoxystearate, which were resolved at the chromatographic conditions applied. Results showed that these compounds, which are formed from methyl oleate, were not detected in the high-linoleic sample, but occurred at non-negligible levels in the oxidized FAME obtained from HOSO. Copyright © 2012 Elsevier B.V. All rights reserved.

Evaluation of real time PCR assays for the detection and enumeration of enterohemorrhagic Escherichia coli directly from cattle feces.

PubMed

Luedtke, Brandon E; Bono, James L; Bosilevac, Joseph M

2014-10-01

Shiga toxin-producing Escherichia coli are a growing concern in the area of food safety, and the United States Department of Agriculture Food Safety and Inspection Service has identified the serotypes O26, O45, O103, O111, O121, O145, and O157 as adulterants in certain types of raw beef. The most relevant to human disease are the enterohemorrhagic E. coli (EHEC) strains that possess intimin (eae), Shiga toxin 1 and/or 2 (stx1-2), and in most cases the conserved pO157 or pO157 like virulence plasmid. Contamination of raw beef with EHEC is likely to occur via the transfer of cattle feces on hides to the carcass. To detect EHEC directly from cattle feces, we evaluated the utility of a multiplex real time PCR assay that targets the EHEC associated gene target ecf1 in combination with eae and stx1-2. Our assay had an increased sensitivity and provided a reliable limit of detection (LOD) of 1.25×10(3)colony-forming unitspermL (CFUs/mL) in an EHEC spiked fecal background. In addition, we evaluated the use of a duplex qPCR assay using ecf1 for the enumeration of total EHEC directly from cattle feces. The reliable limit of quantification (LOQ) was determined to be 1.25×10(3)CFUs/mL. Our assay requires minimal sample processing and provides LOD and LOQ of EHEC directly from cattle feces that are the lowest reported. The application of this assay towards the identification of cattle shedding EHEC at a level above 1.25×10(3)CFUs/mL could be a first line of defense in identifying cattle shedding these pathogens. Published by Elsevier B.V.

A fast liquid chromatography-tandem mass spectrometry method for determining benzodiazepines and analogues in urine. Validation and application to real cases of forensic interest.

PubMed

Salomone, Alberto; Gerace, Enrico; Brizio, Paola; Gennaro, M Carla; Vincenti, Marco

2011-11-01

A fast liquid chromatographic/tandem mass spectrometric method was developed for the simultaneous determination in human urine of seventeen benzodiazepines, four relevant metabolites together plus zolpidem and zopiclone. The sample preparation, optimized to take into account the matrix effect, was based on enzymatic hydrolysis and liquid-liquid extraction. The separation of the twenty-three analytes was achieved in less than eight minutes. The whole methodology was fully validated according to UNI EN ISO/IEC 17025:2005 rules and 2006 SOFT/AAFS guidelines. Selectivity, linearity range, identification (LOD) and quantitation (LOQ) limits, precision, accuracy and recovery were evaluated. For all the species the signal/concentration linearity was satisfactory in the 50-1000 ng/mL concentration range. The limits of detection ranged from 0.5 to 30 ng/mL and LOQs from 1.7 to 100.0 ng/mL. Precisions were in the ranges 5.0-11.8%, 1.5-11.0% and 1.1-4.4% for low (100 ng/mL), medium (300 ng/mL) and high (1000 ng/mL) concentration, respectively. The accuracy, expressed as bias% was within ± 25 % for all the analytes. The recovery values, evaluated at 300 ng/mL concentration, ranged from 56.2% to 98.8%. The present method for the determination of several benzodiazepines, zolpidem and zopiclone in human urine proved to be simple, fast, specific and sensitive. The quantification by LC-MS/MS was successfully applied to 329 forensic cases among driving re-licensing, car accidents and alleged sexual violence cases. Copyright © 2011 Elsevier B.V. All rights reserved.

Development and comparison of HPLC-MS/MS and UPLC-MS/MS methods for determining eight coccidiostats in beef.

PubMed

Zhao, Xia; Wang, Bo; Xie, Kaizhou; Liu, Jianyu; Zhang, Yangyang; Wang, Yajuan; Guo, Yawen; Zhang, Genxi; Dai, Guojun; Wang, Jinyu

2018-06-15

A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method and an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determining eight coccidiostat (halofuginone, lasalocid, maduramicin, monensin, narasin, nigericin, robenidine and salinomycin) residues in beef were developed and compared. Samples were extracted with a mixture of acetic acid, acetonitrile and ethyl acetate and were then purified on a C 18 solid-phase extraction (SPE) column. The purified samples were analyzed by HPLC-MS/MS and UPLC-MS/MS, using 0.1% formic acid-water solution (A) and pure methanol (B) as the mobile phase. The samples were fractionated on a C 18 column using different gradient elution procedures, followed by qualitative analysis using a mass spectrometer operated in multiple reaction monitoring (MRM) mode with positive electrospray ionization; the external standard method was used for quantitation. At spiked levels that ranged from the limit of quantification (LOQ) to 100 μg/kg, the average recoveries were 71.96%-100.32% and 71.24%-89.24%, with relative standard deviations (RSDs) of 2.65%-12.38% and 2.98%-14.86% for UPLC-MS/MS and HPLC-MS/MS, respectively. The limits of detection (LODs) and LOQs of the eight coccidiostats were 0.14-0.32 μg/kg and 0.43-1.21 μg/kg, respectively, for UPLC-MS/MS analysis and 0.16-0.58 μg/kg and 0.53-1.92 μg/kg, respectively, for HPLC-MS/MS analysis. Both methods had good accuracy and precision, but UPLC-MS/MS had higher sensitivity than HPLC-MS/MS. Copyright © 2018 Elsevier B.V. All rights reserved.

Single solid phase extraction method for the simultaneous analysis of polar and non-polar pesticides in urine samples by gas chromatography and ultra high pressure liquid chromatography coupled to tandem mass spectrometry.

PubMed

Cazorla-Reyes, Rocío; Fernández-Moreno, José Luis; Romero-González, Roberto; Frenich, Antonia Garrido; Vidal, José Luis Martínez

2011-07-15

A new multiresidue method has been developed and validated for the simultaneous extraction of more than two hundred pesticides, including non-polar and polar pesticides (carbamates, organochlorine, organophosphorous, pyrethroids, herbicides and insecticides) in urine at trace levels by gas and ultra high pressure liquid chromatography coupled to ion trap and triple quadrupole mass spectrometry, respectively (GC-IT-MS/MS, UHPLC-QqQ-MS/MS). Non-polar and polar pesticides were simultaneously extracted from urine samples by a simple and fast solid phase extraction (SPE) procedure using C(18) cartridges as sorbent, and dichloromethane as elution solvent. Recovery was in the range of 60-120%. Precision values expressed as relative standard deviation (RSD) were lower than 25%. Identification and confirmation of the compounds were performed by the use of retention time windows, comparison of spectra (GC-amenable compounds) or the estimation of the ion ratio (LC-amenable compounds). For GC-amenable pesticides, limits of detection (LODs) ranged from 0.001 to 0.436 μg L(-1) and limits of quantification (LOQs) from 0.003 to 1.452 μg L(-1). For LC-amenable pesticides, LODs ranged from 0.003 to 1.048 μg L(-1) and LOQs ranged from 0.011 to 3.494 μg L(-1). Finally, the optimized method was applied to the analysis of fourteen real samples of infants from agricultural population. Some pesticides such as methoxyfenozide, tebufenozide, piperonyl butoxide and propoxur were found at concentrations ranged from 1.61 to 24.4 μg L(-1), whereas methiocarb sulfoxide was detected at trace levels in two samples. Copyright © 2011 Elsevier B.V. All rights reserved.

A newly validated high-performance liquid chromatography method with diode array ultraviolet detection for analysis of the antimalarial drug primaquine in the blood plasma.

PubMed

Carmo, Ana Paula Barbosa do; Borborema, Manoella; Ribeiro, Stephan; De-Oliveira, Ana Cecilia Xavier; Paumgartten, Francisco Jose Roma; Moreira, Davyson de Lima

2017-01-01

Primaquine (PQ) diphosphate is an 8-aminoquinoline antimalarial drug with unique therapeutic properties. It is the only drug that prevents relapses of Plasmodium vivax or Plasmodium ovale infections. In this study, a fast, sensitive, cost-effective, and robust method for the extraction and high-performance liquid chromatography with diode array ultraviolet detection (HPLC-DAD-UV ) analysis of PQ in the blood plasma was developed and validated. After plasma protein precipitation, PQ was obtained by liquid-liquid extraction and analyzed by HPLC-DAD-UV with a modified-silica cyanopropyl column (250mm × 4.6mm i.d. × 5μm) as the stationary phase and a mixture of acetonitrile and 10mM ammonium acetate buffer (pH = 3.80) (45:55) as the mobile phase. The flow rate was 1.0mL·min-1, the oven temperature was 50OC, and absorbance was measured at 264nm. The method was validated for linearity, intra-day and inter-day precision, accuracy, recovery, and robustness. The detection (LOD) and quantification (LOQ) limits were 1.0 and 3.5ng·mL-1, respectively. The method was used to analyze the plasma of female DBA-2 mice treated with 20mg.kg-1 (oral) PQ diphosphate. By combining a simple, low-cost extraction procedure with a sensitive, precise, accurate, and robust method, it was possible to analyze PQ in small volumes of plasma. The new method presents lower LOD and LOQ limits and requires a shorter analysis time and smaller plasma volumes than those of previously reported HPLC methods with DAD-UV detection. The new validated method is suitable for kinetic studies of PQ in small rodents, including mouse models for the study of malaria.

Characterization of the exogenous insert and development of event-specific PCR detection methods for genetically modified Huanong No. 1 papaya.

PubMed

Guo, Jinchao; Yang, Litao; Liu, Xin; Guan, Xiaoyan; Jiang, Lingxi; Zhang, Dabing

2009-08-26

Genetically modified (GM) papaya (Carica papaya L.), Huanong No. 1, was approved for commercialization in Guangdong province, China in 2006, and the development of the Huanong No. 1 papaya detection method is necessary for implementing genetically modified organism (GMO) labeling regulations. In this study, we reported the characterization of the exogenous integration of GM Huanong No. 1 papaya by means of conventional polymerase chain reaction (PCR) and thermal asymmetric interlaced (TAIL)-PCR strategies. The results suggested that one intact copy of the initial construction was integrated in the papaya genome and which probably resulted in one deletion (38 bp in size) of the host genomic DNA. Also, one unintended insertion of a 92 bp truncated NptII fragment was observed at the 5' end of the exogenous insert. Furthermore, we revealed its 5' and 3' flanking sequences between the insert DNA and the papaya genomic DNA, and developed the event-specific qualitative and quantitative PCR assays for GM Huanong No. 1 papaya based on the 5' integration flanking sequence. The relative limit of detection (LOD) of the qualitative PCR assay was about 0.01% in 100 ng of total papaya genomic DNA, corresponding to about 25 copies of papaya haploid genome. In the quantitative PCR, the limits of detection and quantification (LOD and LOQ) were as low as 12.5 and 25 copies of papaya haploid genome, respectively. In practical sample quantification, the quantified biases between the test and true values of three samples ranged from 0.44% to 4.41%. Collectively, we proposed that all of these results are useful for the identification and quantification of Huanong No. 1 papaya and its derivates.

Simultaneous determination of chromones and coumarins in Radix Saposhnikoviae by high performance liquid chromatography with diode array and tandem mass detectors.

PubMed

Kim, Min Kyung; Yang, Dong-Hyug; Jung, Mihye; Jung, Eun Ha; Eom, Han Young; Suh, Joon Hyuk; Min, Jung Won; Kim, Unyong; Min, Hyeyoung; Kim, Jinwoong; Han, Sang Beom

2011-09-16

Methods using high performance liquid chromatography with diode array detection (HPLC-DAD) and tandem mass spectrometry (HPLC-MS/MS) were developed and validated for the simultaneous determination of 5 chromones and 6 coumarins: prim-O-glucosylcimifugin (1), cimifugin (2), nodakenin (3), 4'-O-β-d-glucosyl-5-O-methylvisamminol (4), sec-O-glucosylhamaudol (5), psoralen (6), bergapten (7), imperatorin (8), phellopterin (9), 3'-O-angeloylhamaudol (10) and anomalin (11), in Radix Saposhnikoviae. The separation conditions for HPLC-DAD were optimized using an Ascentis Express C18 (4.6 mm×100 mm, 2.7 μm particle size) fused-core column. The mobile phase was composed of 10% aqueous acetonitrile (A) and 90% acetonitrile (B) and the elution was performed under a gradient mode at a flow rate of 1.0 mL/min. The detection wavelength was set at 300 nm. The HPLC-DAD method yielded a base line separation of the 11 components in 50% methanol extract of Radix Saposhnikoviae with no interfering peaks detected. The HPLC-DAD method was validated in terms of linearity, accuracy and precision (intra- and inter-day), limit of quantification (LOQ), recovery, and robustness. Specific determination of the 11 components was also accomplished by a triple quadrupole tandem mass spectrometer equipped with an electrospray ionization (ESI) source. This HPLC-MS/MS method was also validated by determining the linearity, limit of quantification, accuracy, and precision. Quantification of the 11 components in 51 commercial Radix Saposhnikoviae samples was successfully performed using the developed HPLC-DAD method. The identity, batch-to-batch consistency, and authenticity of Radix Saposhnikoviae were successfully monitored by the proposed HPLC-DAD and HPLC-MS/MS methods. Copyright © 2011 Elsevier B.V. All rights reserved.

Analytical Performance of a Multiplex Real-Time PCR Assay Using TaqMan Probes for Quantification of Trypanosoma cruzi Satellite DNA in Blood Samples

PubMed Central

Abate, Teresa; Cayo, Nelly M.; Parrado, Rudy; Bello, Zoraida Diaz; Velazquez, Elsa; Muñoz-Calderon, Arturo; Juiz, Natalia A.; Basile, Joaquín; Garcia, Lineth; Riarte, Adelina; Nasser, Julio R.; Ocampo, Susana B.; Yadon, Zaida E.; Torrico, Faustino; de Noya, Belkisyole Alarcón; Ribeiro, Isabela; Schijman, Alejandro G.

2013-01-01

Background The analytical validation of sensitive, accurate and standardized Real-Time PCR methods for Trypanosoma cruzi quantification is crucial to provide a reliable laboratory tool for diagnosis of recent infections as well as for monitoring treatment efficacy. Methods/Principal Findings We have standardized and validated a multiplex Real-Time quantitative PCR assay (qPCR) based on TaqMan technology, aiming to quantify T. cruzi satellite DNA as well as an internal amplification control (IAC) in a single-tube reaction. IAC amplification allows rule out false negative PCR results due to inhibitory substances or loss of DNA during sample processing. The assay has a limit of detection (LOD) of 0.70 parasite equivalents/mL and a limit of quantification (LOQ) of 1.53 parasite equivalents/mL starting from non-boiled Guanidine EDTA blood spiked with T. cruzi CL-Brener stock. The method was evaluated with blood samples collected from Chagas disease patients experiencing different clinical stages and epidemiological scenarios: 1- Sixteen Venezuelan patients from an outbreak of oral transmission, 2- Sixty three Bolivian patients suffering chronic Chagas disease, 3- Thirty four Argentinean cases with chronic Chagas disease, 4- Twenty seven newborns to seropositive mothers, 5- A seronegative receptor who got infected after transplantation with a cadaveric kidney explanted from an infected subject. Conclusions/Significance The performing parameters of this assay encourage its application to early assessment of T. cruzi infection in cases in which serological methods are not informative, such as recent infections by oral contamination or congenital transmission or after transplantation with organs from seropositive donors, as well as for monitoring Chagas disease patients under etiological treatment. PMID:23350002

Data representing two separate LC-MS methods for detection and quantification of water-soluble and fat-soluble vitamins in tears and blood serum.

PubMed

Khaksari, Maryam; Mazzoleni, Lynn R; Ruan, Chunhai; Kennedy, Robert T; Minerick, Adrienne R

2017-04-01

Two separate liquid chromatography (LC)-mass spectrometry (MS) methods were developed for determination and quantification of water-soluble and fat-soluble vitamins in human tear and blood serum samples. The water-soluble vitamin method was originally developed to detect vitamins B 1 , B 2 , B 3 (nicotinamide), B 5 , B 6 (pyridoxine), B 7 , B 9 and B 12 while the fat-soluble vitamin method detected vitamins A, D 3 , 25(OH)D 3, E and K 1 . These methods were then validated with tear and blood serum samples. In this data in brief article, we provide details on the two LC-MS methods development, methods sensitivity, as well as precision and accuracy for determination of vitamins in human tears and blood serum. These methods were then used to determine the vitamin concentrations in infant and parent samples under a clinical study which were reported in "Determination of Water-Soluble and Fat-Soluble Vitamins in Tears and Blood Serum of Infants and Parents by Liquid Chromatography/Mass Spectrometry DOI:10.1016/j.exer.2016.12.007 [1]". This article provides more details on comparison of vitamin concentrations in the samples with the ranges reported in the literature along with the medically accepted normal ranges. The details on concentrations below the limits of detection (LOD) and limits of quantification (LOQ) are also discussed. Vitamin concentrations were also compared and cross-correlated with clinical data and nutritional information. Significant differences and strongly correlated data were reported in [1]. This article provides comprehensive details on the data with slight differences or slight correlations.

Determination of cocaine, benzoylecgonine and cocaethylene in human hair by solid-phase microextraction and gas chromatography-mass spectrometry.

PubMed

de Toledo, Fernanda Crossi Pereira; Yonamine, Mauricio; de Moraes Moreau, Regina Lucia; Silva, Ovandir Alves

2003-12-25

The present work describes a highly precise and sensitive method developed to detect cocaine (COC), benzoylecgonine (BE, its main metabolite) and cocaethylene (CE, transesterification product of the coingestion of COC with ethanol) in human head hair samples. The method was based on an alkylchloroformate derivatization of benzoylecgonine and the extraction of the analytes by solid-phase microextraction (SPME). Gas chromatography-mass spectrometry (GC-MS) was used to identify and quantify the analytes in selected ion monitoring mode (SIM). The limits of quantification and detection (LOQ and LOD) were: 0.1 ng/mg for COC and CE, and 0.5 ng/mg for BE. Good inter- and intra-assay precision was observed. The dynamic range of the assay was 0.1-50 ng/mg. The method is not time consuming and was shown to be easy to perform.

Studies on the electrochemical behavior of thiazolidine and its applications using a flow-through chronoamperometric sensor based on a gold electrode.

PubMed

Wang, Lai-Hao; Li, Wen-Jie

2011-09-06

The electrochemical behaviors of thiazolidine (tetrahydrothiazole) on gold and platinum electrodes were investigated in a Britton-Robinson buffer (pH 2.77-11.61), acetate buffer (pH 4.31), phosphate buffer solutions (pH 2.11 and 6.38) and methanol or acetonitrile containing various supporting electrolytes. Detection was based on a gold wire electrochemical signal obtained with a supporting electrolyte containing 20% methanol-1.0 mM of phosphate buffer (pH 6.87, potassium dihydrogen phosphate and dipotassium hydrogen phosphate) as the mobile phase. Comparison with results obtained with a commercial amperometric detector shows good agreement. Using the chronoamperometric sensor with the current at a constant potential, and measurements with suitable experimental parameters, a linear concentration from 0.05 to 16 mg L-1 was found. The limit of quantification (LOQ) of the method for thiazolidine was found to be 1 ng.

Analysis of bromate in drinking water using liquid chromatography-tandem mass spectrometry without sample pretreatment.

PubMed

Kosaka, Koji; Asami, Mari; Takei, Kanako; Akiba, Michihiro

2011-01-01

An analytical method for determining bromate in drinking water was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The (18)O-enriched bromate was used as an internal standard. The limit of quantification (LOQ) of bromate was 0.2 µg/L. The peak of bromate was separated from those of coexisting ions (i.e., chloride, nitrate and sulfate). The relative and absolute recoveries of bromate in two drinking water samples and in a synthesized ion solution (100 mg/L chloride, 10 mg N/L nitrate, and 100 mg/L sulfate) were 99-105 and 94-105%, respectively. Bromate concentrations in 11 drinking water samples determined by LC-MS/MS were <0.2-2.3 µg/L. The results of the present study indicated that the proposed method was suitable for determining bromate concentrations in drinking water without sample pretreatment.

Validated spectrofluorometric method for determination of gemfibrozil in self nanoemulsifying drug delivery systems (SNEDDS)

NASA Astrophysics Data System (ADS)

Sierra Villar, Ana M.; Calpena Campmany, Ana C.; Bellowa, Lyda Halbaut; Trenchs, Monserrat Aróztegui; Naveros, Beatriz Clares

2013-09-01

A spectrofluorometric method has been developed and validated for the determination of gemfibrozil. The method is based on the excitation and emission capacities of gemfibrozil with excitation and emission wavelengths of 276 and 304 nm respectively. This method allows de determination of the drug in a self-nanoemulsifying drug delivery system (SNEDDS) for improve its intestinal absorption. Results obtained showed linear relationships with good correlation coefficients (r2 > 0.999) and low limits of detection and quantification (LOD of 0.075 μg mL-1 and LOQ of 0.226 μg mL-1) in the range of 0.2-5 μg mL-1, equally this method showed a good robustness and stability. Thus the amounts of gemfibrozil released from SNEDDS contained in gastro resistant hard gelatine capsules were analysed, and release studies could be performed satisfactorily.

Validated spectrofluorometric method for determination of gemfibrozil in self nanoemulsifying drug delivery systems (SNEDDS).

PubMed

Sierra Villar, Ana M; Calpena Campmany, Ana C; Bellowa, Lyda Halbaut; Trenchs, Monserrat Aróztegui; Naveros, Beatriz Clares

2013-09-01

A spectrofluorometric method has been developed and validated for the determination of gemfibrozil. The method is based on the excitation and emission capacities of gemfibrozil with excitation and emission wavelengths of 276 and 304 nm respectively. This method allows de determination of the drug in a self-nanoemulsifying drug delivery system (SNEDDS) for improve its intestinal absorption. Results obtained showed linear relationships with good correlation coefficients (r(2)>0.999) and low limits of detection and quantification (LOD of 0.075 μg mL(-1) and LOQ of 0.226 μg mL(-1)) in the range of 0.2-5 μg mL(-1), equally this method showed a good robustness and stability. Thus the amounts of gemfibrozil released from SNEDDS contained in gastro resistant hard gelatine capsules were analysed, and release studies could be performed satisfactorily. Copyright © 2013 Elsevier B.V. All rights reserved.

Monitoring and evaluating the quality consistency of Compound Bismuth Aluminate tablets by a simple quantified ratio fingerprint method combined with simultaneous determination of five compounds and correlated with antioxidant activities.

PubMed

Liu, Yingchun; Liu, Zhongbo; Sun, Guoxiang; Wang, Yan; Ling, Junhong; Gao, Jiayue; Huang, Jiahao

2015-01-01

A combination method of multi-wavelength fingerprinting and multi-component quantification by high performance liquid chromatography (HPLC) coupled with diode array detector (DAD) was developed and validated to monitor and evaluate the quality consistency of herbal medicines (HM) in the classical preparation Compound Bismuth Aluminate tablets (CBAT). The validation results demonstrated that our method met the requirements of fingerprint analysis and quantification analysis with suitable linearity, precision, accuracy, limits of detection (LOD) and limits of quantification (LOQ). In the fingerprint assessments, rather than using conventional qualitative "Similarity" as a criterion, the simple quantified ratio fingerprint method (SQRFM) was recommended, which has an important quantified fingerprint advantage over the "Similarity" approach. SQRFM qualitatively and quantitatively offers the scientific criteria for traditional Chinese medicines (TCM)/HM quality pyramid and warning gate in terms of three parameters. In order to combine the comprehensive characterization of multi-wavelength fingerprints, an integrated fingerprint assessment strategy based on information entropy was set up involving a super-information characteristic digitized parameter of fingerprints, which reveals the total entropy value and absolute information amount about the fingerprints and, thus, offers an excellent method for fingerprint integration. The correlation results between quantified fingerprints and quantitative determination of 5 marker compounds, including glycyrrhizic acid (GLY), liquiritin (LQ), isoliquiritigenin (ILG), isoliquiritin (ILQ) and isoliquiritin apioside (ILA), indicated that multi-component quantification could be replaced by quantified fingerprints. The Fenton reaction was employed to determine the antioxidant activities of CBAT samples in vitro, and they were correlated with HPLC fingerprint components using the partial least squares regression (PLSR) method. In summary, the method of multi-wavelength fingerprints combined with antioxidant activities has been proved to be a feasible and scientific procedure for monitoring and evaluating the quality consistency of CBAT.

A Liquid Chromatography – Tandem Mass Spectrometry Approach for the Identification of Mebendazole Residue in Pork, Chicken, and Horse

PubMed Central

Lee, Ji Sun; Cho, Soo Hee; Lim, Chae Mi; Chang, Moon Ik; Joo, Hyun Jin; Park, Hyun Jin

2017-01-01

A confirmatory and quantitative method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of mebendazole and its hydrolyzed and reduced metabolites in pork, chicken, and horse muscles was developed and validated in this study. Anthelmintic compounds were extracted with ethyl acetate after sample mixture was made alkaline followed by liquid chromatographic separation using a reversed phase C18 column. Gradient elution was performed with a mobile phase consisting of water containing 10 mM ammonium formate and methanol. This confirmatory method was validated according to EU requirements. Evaluated validation parameters included specificity, accuracy, precision (repeatability and within-laboratory reproducibility), analytical limits (decision limit and detection limit), and applicability. Most parameters were proved to be conforming to the EU requirements. The decision limit (CCα) and detection capability (CCβ) for all analytes ranged from 15.84 to 17.96 μgkg-1. The limit of detection (LOD) and the limit of quantification (LOQ) for all analytes were 0.07 μgkg-1 and 0.2 μgkg-1, respectively. The developed method was successfully applied to monitoring samples collected from the markets in major cities and proven great potential to be used as a regulatory tool to determine mebendazole residues in animal based foods. PMID:28085912

Detailed phenolic composition of Vidal grape pomace by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

PubMed

Luo, Lanxin; Cui, Yan; Zhang, Shuting; Li, Lingxi; Suo, Hao; Sun, Baoshan

2017-11-15

Vidal Blanc grape (Vitis vinifera cv.) is the predominant white grape variety used for the production of icewine in China's Liaoning province. In this paper, the development and validation of the method by ultrahigh-performance liquid chromatography-tandem mass spectrometry has been performed for determination of the detailed phenolic composition in the skin, seed and stem of Vidal grapes. The validation of the method was realized by calculating the linearity, repeatability, precision, stability and the limits of detection (LOD) and quantification (LOQ) of standard solutions. All the curves exhibited good linearity (r 2 >0.9997) and the LOD and LOQ were in the range of 0.002-0.025 and 0.006-0.086μg/ml, respectively. Good repeatability (RSD<4.3%) and stability (RSD<3.7%) were also found. Results confirmed that the developed method was more effective and sensitive for simultaneous determination of the major phenolic compounds in Vidal grape pomace. The optimized and validated method of ultrahigh-performance liquid chromatography tandem two complementary techniques, fourier transform ion cyclotron resonance mass spectrometry and triple-quadrupole mass spectrometry, allowed to identify and quantify up to 35 phenolic compounds in Vidal grape pomace, which has, as far as we know, been reported this grapevine variety for the first time. Seeds, skins and stems exhibited different qualitative and quantitative phenolic profiles. These results provided useful information for recovery of phenolic antioxidants from different parts of icewine pomace. Copyright © 2017. Published by Elsevier B.V.

Persistence and risk assessment of emamectin benzoate residues on okra fruits and soil.

PubMed

Jyot, Gagan; Mandal, Kousik; Chahil, G S; Singh, Balwinder

2014-08-01

Emamectin benzoate, a synthetic derivative of abamectin, is found effective against fruit borer and jassid in okra crops. The present studies were carried out to study the dissipation pattern of emamectin benzoate on okra and to suggest a suitable waiting period for the safety of consumers. Following three applications of emamectin benzoate (Proclaim 5 SG) at 68.1 and 136.2 g a.i. ha-1, the average initial deposits of emamectin benzoate were observed to be 0.22 and 0.42mg kg-1, respectively. These residues dissipated below the limit of quantification (LOQ) of 0.05 mg kg-1 after 5 days at both the dosages. Soil samples collected after 15 days did not reveal the presence of emamectin benzoate at LOQ of 0.05 mg kg-1. Acceptable daily intake (ADI) of emamectin benzoate is 0.0005 mg kg-1 body weight day-1, which means an adult of 55 kg weight can safely tolerate an intake of 27.50 microg emamectin benzoate. Assuming an average consumption of 80 g okra fruit and multiplying it by average and maximum residues observed on 0 day at recommended dosage, the intake of emamectin benzoate comes out to be about 20 Itg and these values are quite safe in comparison to its ADI. These studies, therefore, suggest that the use of emamectin benzoate at the minimum effective dosages do not seem to pose any hazards to the consumers if a waiting period of 1 day is observed.

Consistency in trophic magnification factors of cyclic methyl siloxanes in pelagic freshwater food webs leading to brown trout.

PubMed

Borgå, Katrine; Fjeld, Eirik; Kierkegaard, Amelie; McLachlan, Michael S

2013-12-17

Cyclic volatile methyl siloxanes (cVMS) concentrations were analyzed in the pelagic food web of two Norwegian lakes (Mjøsa, Randsfjorden), and in brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) collected in a reference lake (Femunden), in 2012. Lakes receiving discharge from wastewater treatment plants (Mjøsa and Randsfjorden) had cVMS concentrations in trout that were up to 2 orders of magnitude higher than those in Femunden, where most samples were close to the limit of quantification (LOQ). Food web biomagnification of cVMS in Mjøsa and Randsfjorden was quantified by estimation of trophic magnification factors (TMFs). TMF for legacy persistent organic pollutants (POPs) were analyzed for comparison. Both decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) biomagnified with TMFs of 2.9 (2.1-4.0) and 2.3 (1.8-3.0), respectively. Octamethylcyclotetrasiloxane (D4) was below the LOQ in the majority of samples and had substantially lower biomagnification than for D5 and D6. The cVMS TMFs did not differ between the lakes, whereas the legacy POP TMFs were higher in Mjøsa than inRandsfjorden. Whitefish had lower cVMS bioaccumulation compared to legacy POPs, and affected the TMF significance for cVMS, but not for POPs. TMFs of D5 and legacy contaminants in Lake Mjøsa were consistent with those previously measured in Mjøsa.

Evaluation of optimized bronchoalveolar lavage sampling designs for characterization of pulmonary drug distribution.

PubMed

Clewe, Oskar; Karlsson, Mats O; Simonsson, Ulrika S H

2015-12-01

Bronchoalveolar lavage (BAL) is a pulmonary sampling technique for characterization of drug concentrations in epithelial lining fluid and alveolar cells. Two hypothetical drugs with different pulmonary distribution rates (fast and slow) were considered. An optimized BAL sampling design was generated assuming no previous information regarding the pulmonary distribution (rate and extent) and with a maximum of two samples per subject. Simulations were performed to evaluate the impact of the number of samples per subject (1 or 2) and the sample size on the relative bias and relative root mean square error of the parameter estimates (rate and extent of pulmonary distribution). The optimized BAL sampling design depends on a characterized plasma concentration time profile, a population plasma pharmacokinetic model, the limit of quantification (LOQ) of the BAL method and involves only two BAL sample time points, one early and one late. The early sample should be taken as early as possible, where concentrations in the BAL fluid ≥ LOQ. The second sample should be taken at a time point in the declining part of the plasma curve, where the plasma concentration is equivalent to the plasma concentration in the early sample. Using a previously described general pulmonary distribution model linked to a plasma population pharmacokinetic model, simulated data using the final BAL sampling design enabled characterization of both the rate and extent of pulmonary distribution. The optimized BAL sampling design enables characterization of both the rate and extent of the pulmonary distribution for both fast and slowly equilibrating drugs.

Quantification of Inflammasome Adaptor Protein ASC in Biological Samples by Multiple-Reaction Monitoring Mass Spectrometry.

PubMed

Ulke-Lemée, Annegret; Lau, Arthur; Nelson, Michelle C; James, Matthew T; Muruve, Daniel A; MacDonald, Justin A

2018-06-09

Inflammation is an integral component of many diseases, including chronic kidney disease (CKD). ASC (apoptosis-associated speck-like protein containing CARD, also PYCARD) is the key inflammasome adaptor protein in the innate immune response. Since ASC specks, a macromolecular condensate of ASC protein, can be released by inflammasome-activated cells into the extracellular space to amplify inflammatory responses, the ASC protein could be an important biomarker in diagnostic applications. Herein, we describe the development and validation of a multiple reaction monitoring mass spectrometry (MRM-MS) assay for the accurate quantification of ASC in human biospecimens. Limits of detection and quantification for the signature DLLLQALR peptide (used as surrogate for the target ASC protein) were determined by the method of standard addition using synthetic isotope-labeled internal standard (SIS) peptide and urine matrix from a healthy donor (LOQ was 8.25 pM, with a ~ 1000-fold linear range). We further quantified ASC in the urine of CKD patients (8.4 ± 1.3 ng ASC/ml urine, n = 13). ASC was positively correlated with proteinuria and urinary IL-18 in CKD samples but not with urinary creatinine. Unfortunately, the ASC protein is susceptible to degradation, and patient urine that was thawed and refrozen lost 85% of the ASC signal. In summary, the MRM-MS assay provides a robust means to quantify ASC in biological samples, including clinical biospecimens; however, sample collection and storage conditions will have a critical impact on assay reliability.

Determination of neonicotinoid pesticides residues in agricultural samples by solid-phase extraction combined with liquid chromatography-tandem mass spectrometry.

PubMed

Xie, Wen; Han, Chao; Qian, Yan; Ding, Huiying; Chen, Xiaomei; Xi, Junyang

2011-07-15

This work reports a new sensitive multi-residue liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for detection, confirmation and quantification of six neonicotinoid pesticides (dinotefuran, thiamethoxam, clothiandin, imidacloprid, acetamiprid and thiacloprid) in agricultural samples (chestnut, shallot, ginger and tea). Activated carbon and HLB solid-phase extraction cartridges were used for cleaning up the extracts. Analysis is performed by LC-MS/MS operated in the multiple reaction monitoring (MRM) mode, acquiring two specific precursor-product ion transitions per target compound. Quantification was carried by the internal standard method with D(4)-labeled imidacloprid. The method showed excellent linearity (R(2)≥0.9991) and precision (relative standard deviation, RSD≤8.6%) for all compounds. Limits of quantification (LOQs) were 0.01 mg kg(-1) for chestnut, shallot, ginger sample and 0.02 mg kg(-1) for tea sample. The average recoveries, measured at three concentrations levels (0.01 mg kg(-1), 0.02 mg kg(-1) and 0.1 mg kg(-1) for chestnut, shallot, ginger sample, 0.02 mg kg(-1), 0.04 mg kg(-1) and 0.2 mg kg(-1) for tea sample), were in the range 82.1-108.5%. The method was satisfactorily validated for the analysis of 150 agricultural samples (chestnut, shallot, ginger and tea). Imidacloprid and acetamiprid were detected at concentration levels ranging from 0.05 to 3.6 mg kg(-1). Copyright © 2011 Elsevier B.V. All rights reserved.

Determination of the Marker Diarylheptanoid Phytoestrogens in Curcuma comosa Rhizomes and Selected Herbal Medicinal Products by HPLC-DAD.

PubMed

Yingngam, Bancha; Brantner, Adelheid; Jinarat, Damrongsak; Kaewamatawong, Rawiwun; Rungseevijitprapa, Wandee; Suksamrarn, Apichart; Piyachaturawat, Pawinee; Chokchaisiri, Ratchanaporn

2018-01-01

A method for quantification of diarylheptanoids in Curcuma comosa rhizomes and selected pharmaceutical preparations was established by using HPLC-diode array detector (DAD). The chromatographic separation of three diarylheptanoids [(3S)-1-(3,4-dihydroxy-phenyl)-7-phenyl-(6E)-6-hepten-3-ol (1), (3R)-1,7-diphenyl-(4E,6E)-4,6-heptadien-3-ol (2), and (3S)-1,7-diphenyl-(6E)-6-hepten-3-ol (3)] was performed on a Luna C 18 analytical column using gradient elution with 0.5% acetic acid in water and acetonitrile with a flow rate of 1 mL/min and a column temperature of 35°C. The calibration curves for the analytes showed good linearity (R 2 >0.999), high precision (relative standard deviation (RSD) <2%) and acceptable recovery (98.35-103.90%, RSD <2%). The limit of detection (LOD) and limit of quantification (LOQ) were 0.06-0.22 and 0.18-0.69 µg/mL, respectively. The results of all validated parameters were within the limits according to the International Conference on Harmonization (ICH) Guidelines. The established method was successfully applied for qualitative and quantitative determination of the three constituents in different samples of C. comosa and some commercial products in capsules. The simplicity, rapidity, and reliability of the method could be useful for the fingerprint analysis and standardization of diarylheptanoids, which are responsible for the estrogenic activity in raw materials and herbal medicinal products of C. comosa.

Washing effects of limonene on pesticide residues in green peppers.

PubMed

Lu, Hai-Yan; Shen, Yan; Sun, Xing; Zhu, Hong; Liu, Xian-Jin

2013-09-01

The presence of pesticide residues in food has caused much concern. The low health risks and environmental impacts of limonene make it a very interesting solvent for use in green chemistry. Washing effects of limonene on pesticide residues of methyl chlorpyrifos, chlorothalonil, chlorpyrifos, fenpropathrin and deltamethrin were investigated in green pepper. Results showed that washing with a low concentration of limonene for 5 min (where LOQ is limit of quantitation) caused 53.67%,

Simultaneous quantification of monoamine neurotransmitters and their biogenic metabolites intracellularly and extracellularly in primary neuronal cell cultures and in sub-regions of guinea pig brain.

PubMed

Schou-Pedersen, Anne Marie V; Hansen, Stine N; Tveden-Nyborg, Pernille; Lykkesfeldt, Jens

2016-08-15

In the present paper, we describe a validated chromatographic method for the simultaneous quantification of monoamine neurotransmitters and their biogenic metabolites intracellularly and extracellularly in primary neuronal cell culture and in sub-regions of the guinea pig brain. Electrochemical detection provided limits of quantifications (LOQs) between 3.6 and 12nM. Within the linear range, obtained recoveries were from 90.9±9.9 to 120±14% and intra-day and inter-day precisions found to be less than 5.5% and 12%, respectively. The analytical method was applicable for quantification of intracellular and extracellular amounts of monoamine neurotransmitters and their metabolites in guinea pig frontal cortex and hippocampal primary neuronal cell cultures. Noradrenaline, dopamine and serotonin were found to be in a range from 0.31 to 1.7pmol per 2 million cells intracellularly, but only the biogenic metabolites could be detected extracellularly. Distinct differences in monoamine concentrations were observed when comparing concentrations in guinea pig frontal cortex and cerebellum tissue with higher amounts of dopamine and its metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid in frontal cortex, as compared to cerebellum. The chemical turnover in frontal cortex tissue of guinea pig was for serotonin successfully predicted from the turnover observed in the frontal cortex cell culture. In conclusion, the present analytical method shows high precision, accuracy and sensitivity and is broadly applicable to monoamine measurements in cell cultures as well as brain biopsies from animal models used in preclinical neurochemistry. Copyright © 2016 Elsevier B.V. All rights reserved.

SPE coupled to AAS trace determination of Cd(II) and Zn(II) in food samples using amine functionalized GMA-MMA-EGDMA terpolymer: Isotherm and kinetic studies.

PubMed

Islam, Aminul; Kumar, Suneel; Zaidi, Noushi; Ahmad, Hilal

2016-12-15

An ethylenediamine functionalized glycidyl methacrylate (GMA) based terpolymeric chelating resin was synthesized for the separation and preconcentration of Cd(II) and Zn(II) by SPE from bread, rice and fruit juice prior to FAAS determination. The resin was characterized by FT-IR, TGA/DTA, SEM, BET analysis and EDS. Synthesized resin shows a good capacity of 53.96mgg(-1) for Cd(II) and 24.19mgg(-1) for Zn(II) at pH 8.0. Five isotherm equilibrium models were studied to explain the sorption phenomenon out of which Langmuir, Dubinin-Radushkevich, Scatchard and Temkin models were found to be the best fitted. The limit of detection (LOD) and limit of quantification (LOQ) were observed to be 1.5 and 5.1μgL(-1) for Cd and 1.2 and 4.1μgL(-1) for Zn. The reliability of the method was investigated by the analysis of SRM and the recovery of analytes from various spiked food samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Periodic modulation-based stochastic resonance algorithm applied to quantitative analysis for weak liquid chromatography-mass spectrometry signal of granisetron in plasma

NASA Astrophysics Data System (ADS)

Xiang, Suyun; Wang, Wei; Xiang, Bingren; Deng, Haishan; Xie, Shaofei

2007-05-01

The periodic modulation-based stochastic resonance algorithm (PSRA) was used to amplify and detect the weak liquid chromatography-mass spectrometry (LC-MS) signal of granisetron in plasma. In the algorithm, the stochastic resonance (SR) was achieved by introducing an external periodic force to the nonlinear system. The optimization of parameters was carried out in two steps to give attention to both the signal-to-noise ratio (S/N) and the peak shape of output signal. By applying PSRA with the optimized parameters, the signal-to-noise ratio of LC-MS peak was enhanced significantly and distorted peak shape that often appeared in the traditional stochastic resonance algorithm was corrected by the added periodic force. Using the signals enhanced by PSRA, this method extended the limit of detection (LOD) and limit of quantification (LOQ) of granisetron in plasma from 0.05 and 0.2 ng/mL, respectively, to 0.01 and 0.02 ng/mL, and exhibited good linearity, accuracy and precision, which ensure accurate determination of the target analyte.

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

PubMed

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

2016-09-15

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

Multifamily determination of pesticide residues in soya-based nutraceutical products by GC/MS-MS.

PubMed

Páleníková, Agneša; Martínez-Domínguez, Gerardo; Arrebola, Francisco Javier; Romero-González, Roberto; Hrouzková, Svetlana; Frenich, Antonia Garrido

2015-04-15

An analytical method based on a modified QuEChERS extraction coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was evaluated for the determination of 177 pesticides in soya-based nutraceutical products. The QuEChERS method was optimised and different extraction solvents and clean-up approaches were tested, obtaining the most efficient conditions with a mixture of sorbents (PSA, C18, GBC and Zr-Sep(+)). Recoveries were evaluated at 10, 50 and 100 μg/kg and ranged between 70% and 120%. Precision was expressed as relative standard deviation (RSD), and it was evaluated for more than 160 pesticides as intra and inter-day precision, with values always below 20% and 25%, respectively. Limits of detection (LODs) ranged from 0.1 to 10 μg/kg, whereas limits of quantification (LOQs) from 0.5 to 20 μg/kg. The applicability of the method was proved by analysing soya-based nutraceuticals. Two pesticides were found in these samples, malathion and pyriproxyfen, at 11.1 and 1.5 μg/kg respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dissipation, transfer and safety evaluation of emamectin benzoate in tea.

PubMed

Zhou, Li; Luo, Fengjian; Zhang, Xinzhong; Jiang, Yaping; Lou, Zhengyun; Chen, Zongmao

2016-07-01

The dissipation and residue of emamectin benzoate in tea leaves and the residue transfer from tea leaves to tea brew were investigated by modified QuEChERS (quick, easy, cheap, effective, rugged and safe) combined with ultra performance liquid chromatography tandem mass (UPLC-MS/MS). The average recoveries ranged 85.3-101.3% with relative standard deviation (RSD) less than 15%. The limits of quantification (LOQ) were 0.005mgkg(-1) in tea leaves and 0.0004mgL(-1) in brew. Emamectin benzoate dissipated rapidly in tea with half-life (t1/2) of 1.0-1.3days. The terminal residues of emamectin benzoate were less than 0.062mgkg(-1). The leaching rate of emamectin benzoate from freshly-made tea to brew was <5%. The risk of emamectin benzoate at the recommended dosage was negligible to humans depending on risk quotient (RQ) value, that was lower than 1 significantly. This study could provide guidance for the safe use of emamectin benzoate and serve as a reference for the establishment of maximum residue limits (MRLs) in China. Copyright © 2016. Published by Elsevier Ltd.

Development and validation of a HPTLC method for simultaneous estimation of lornoxicam and thiocolchicoside in combined dosage form.

PubMed

Sahoo, Madhusmita; Syal, Pratima; Hable, Asawaree A; Raut, Rahul P; Choudhari, Vishnu P; Kuchekar, Bhanudas S

2011-07-01

To develop a simple, precise, rapid and accurate HPTLC method for the simultaneous estimation of Lornoxicam (LOR) and Thiocolchicoside (THIO) in bulk and pharmaceutical dosage forms. The separation of the active compounds from pharmaceutical dosage form was carried out using methanol:chloroform:water (9.6:0.2:0.2 v/v/v) as the mobile phase and no immiscibility issues were found. The densitometric scanning was carried out at 377 nm. The method was validated for linearity, accuracy, precision, LOD (Limit of Detection), LOQ (Limit of Quantification), robustness and specificity. The Rf values (±SD) were found to be 0.84 ± 0.05 for LOR and 0.58 ± 0.05 for THIO. Linearity was obtained in the range of 60-360 ng/band for LOR and 30-180 ng/band for THIO with correlation coefficients r(2) = 0.998 and 0.999, respectively. The percentage recovery for both the analytes was in the range of 98.7-101.2 %. The proposed method was optimized and validated as per the ICH guidelines.

Migration of bisphenol A into canned tomatoes produced in Italy: dependence on temperature and storage conditions.

PubMed

Errico, Sonia; Bianco, Mariangela; Mita, Luigi; Migliaccio, Marina; Rossi, Sergio; Nicolucci, Carla; Menale, Ciro; Portaccio, Marianna; Gallo, Pasquale; Mita, Damiano G; Diano, Nadia

2014-10-01

A method based on solid-phase extraction followed by liquid chromatography, coupled to UV-visible and fluorescence spectrophotometry, has been developed for determination of bisphenol A (BPA) in canned tomatoes. The limit of quantification (LOQ) of the procedure used is 0.03 μM (0.26 μg BPA/kg tomato). For each of three different tomato based products (peeled, cherry and concentrated paste), 16 samples belonging to six commercial brands, retailed in Italian markets, were tested for migration of BPA epoxy-coating cans. All the tomato samples exhibited migration levels below 0.4 μg/kg, while samples subjected to heating process and/or can's damage by denting, exhibited a significant increase in the migration levels. In any case, no sample contained BPA exceeding the European Union limit for migration, set at 600 μg/kg of food. By comparing the results for each brand, no relevant difference in BPA concentration was found depending on the kind of tomato products. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Determination of residual toluene diisocyanate in sponge bra by gas chromatography].

PubMed

Wang, Aixia; Ye, Ping; Huang, Nan; Chen, Yan; Li, Xinggen

2017-06-08

A gas chromatography (GC) with internal standard method was developed for the determination of residual toluene diisocyanate (TDI) in sponge bra. The samples were extracted with ethyl acetate dehydrated, and cleaned up with 0.22 μm microfiltration membrane. The residual toluene diisocyanate was separated on a DB-624 capillary column using temperature programming. The flame ionization detector (FID) was used at 250 ℃. The inlet temperature was 180 ℃ with nitrogen as carrier gas. The linear range was 10-200 mg/L ( R 2 =0.9989) for TDI. The average recovery ranged from 80.5% to 91.6% with RSD not more than 7.9%( n =6). The limit of detection (LOD) and limit of quantification (LOQ) were 10 mg/kg and 100 mg/kg, respectively. The developed method was then utilized to analyse the 100 batches of sponge bra samples from the manufacturing enterprises, the entity shops and electric business platforms. The method is simple, time-saving and environment friendly with high sensitivity and good reproducibility, and has practical application value due to its low-cost and short-circle.

Application of response surface methodology for determination of methyl red in water samples by spectrophotometry method.

PubMed

Khodadoust, Saeid; Ghaedi, Mehrorang

2014-12-10

In this study a rapid and effective method (dispersive liquid-liquid microextraction (DLLME)) was developed for extraction of methyl red (MR) prior to its determination by UV-Vis spectrophotometry. Influence variables on DLLME such as volume of chloroform (as extractant solvent) and methanol (as dispersive solvent), pH and ionic strength and extraction time were investigated. Then significant variables were optimized by using a Box-Behnken design (BBD) and desirability function (DF). The optimized conditions (100μL of chloroform, 1.3mL of ethanol, pH 4 and 4% (w/v) NaCl) resulted in a linear calibration graph in the range of 0.015-10.0mgmL(-1) of MR in initial solution with R(2)=0.995 (n=5). The limits of detection (LOD) and limit of quantification (LOQ) were 0.005 and 0.015mgmL(-1), respectively. Finally, the DLLME method was applied for determination of MR in different water samples with relative standard deviation (RSD) less than 5% (n=5). Copyright © 2014 Elsevier B.V. All rights reserved.

On-line HPLC-DPPH screening method for evaluation of radical scavenging phenols extracted from apples (Malus domestica L.).

PubMed

Bandoniene, Donata; Murkovic, Michael

2002-04-24

An on-line HPLC-DPPH screening method for phenolic antioxidants in apple methanol/water (80:20, v/v) extracts was applied. The determination of antioxidants was based on a decrease in absorbance at 515 nm after postcolumn reaction of HPLC-separated antioxidants with the 2,2'-diphenyl-1-picrylhydrazyl radicals (DPPH*). Each of the antioxidants separated by the HPLC column was observed as a negative peak corresponding to its antioxidative activity. The on-line method was applied for quantitative analysis of the antioxidants. A linear dependence of negative peak area on concentration of the reference antioxidants was observed. For validation of the on-line method the limit of detection, LOD (microg/mL), and the limit of quantification, LOQ (microg/mL), of the phenolic compounds were determined. Comparison of the UV and DPPH radical quenching chromatograms with authentic compounds identified catechin, chlorogenic acid, caffeic acid, epicatechin, and phloridzin in the apple cultivars (Lobo, Golden Delicious, and Boskoop), and the distribution of total antioxidant activity was calculated.

The Occurrence of Zearalenone in South Korean Feedstuffs between 2009 and 2016.

PubMed

Chang, Hansub; Kim, Woori; Park, Ju-Hee; Kim, Dongho; Kim, Choong-Ryeol; Chung, Soohyun; Lee, Chan

2017-07-15

Mycotoxins produced by Fusarium plant pathogen species have harmful effects on humans and livestock by natural contamination in food and feed. Zearalenone, one of the well-known Fusarium mycotoxins, causes hyperestrogenism and toxicosis resulting in reproductive dysfunction in animals. This study investigated the occurrence of zearalenone in feedstuffs (compound feeds, feed ingredients) between 2009 and 2016 in South Korea to obtain information on zearalenone contamination in feeds for management. A total of 653 animal feed samples (494 compound feeds, 159 feed ingredients) produced domestically were sampled five times from 2009 to 2016 (2009, 2010, 2012, 2014, and 2016) from feed factories in South Korea. The levels of zearalenone were analyzed every year by high-performance liquid chromatography (HPLC) after pretreatment with an immunoaffinity column showing limit of detection (LOD) and limit of quantification (LOQ) of 0.1-3 μg/kg and 0.3-8 μg/kg, respectively. Four feed samples out of 494 compound feeds exceeded the EU and South Korea commission regulations over the eight-year test period, and no feed ingredients exceeded the guidelines.

Ultrasonic-assisted extraction and dispersive liquid-liquid microextraction combined with gas chromatography-mass spectrometry as an efficient and sensitive method for determining of acrylamide in potato chips samples.

PubMed

Zokaei, Maryam; Abedi, Abdol-Samad; Kamankesh, Marzieh; Shojaee-Aliababadi, Saeedeh; Mohammadi, Abdorreza

2017-11-01

In this research, for the first time, we successfully developed ultrasonic-assisted extraction and dispersive liquid-liquid microextraction combined with gas chromatography-mass spectrometry as a new, fast and highly sensitive method for determining of acrylamide in potato chips samples. Xanthydrol was used as a derivatization reagent and parameters affecting in the derivatization and microextraction steps were studied and optimized. Under optimum conditions, the calibration curves showed high levels of linearity (R 2 >0.9993) for acrylamide in the range of 2-500ngmL -1 . The relative standard deviation (RSD) for the seven analyses was 6.8%. The limit of detection (LOD) and limit of quantification (LOQ) were 0.6ngg -1 and 2ngg -1 , respectively. The UAE-DLLME-GC-MS method demonstrated high sensitivity, good linearity, recovery, and enrichment factor. The performance of the new proposed method was evaluated for the determination of acrylamide in various types of chips samples and satisfactory results were obtained. Copyright © 2017 Elsevier Ltd. All rights reserved.

Azocasein Substrate for Determination of Proteolytic Activity: Reexamining a Traditional Method Using Bromelain Samples.

PubMed

Coêlho, Diego F; Saturnino, Thais Peron; Fernandes, Fernanda Freitas; Mazzola, Priscila Gava; Silveira, Edgar; Tambourgi, Elias Basile

2016-01-01

Given the importance of protease's worldwide market, the determination of optimum conditions and the development of a standard protocol are critical during selection of a reliable method to determine its bioactivity. This paper uses quality control theory to validate a modified version of a method proposed by Charney and Tomarelli in 1947. The results obtained showed that using azocasein substrate bromelain had its optimum at 45°C and pH 9 (Glycine-NaOH 100 mM). We also quantified the limit of detection (LoD) and limit of quantification (LoQ) in the above-mentioned optimum (0.072 and 0.494 mg·mL(-1) of azocasein, resp.) and a calibration curve that correlates optical density with the amount of substrate digested. In all analysed samples, we observed a significant decrease in response after storage (around 17%), which suggests its use must be immediately after preparation. Thus, the protocol presented in this paper offers a significant improvement, given that subjective definitions are commonly used in the literature and this simple mathematical approach makes it clear and concise.

Azocasein Substrate for Determination of Proteolytic Activity: Reexamining a Traditional Method Using Bromelain Samples

PubMed Central

Mazzola, Priscila Gava

2016-01-01

Given the importance of protease's worldwide market, the determination of optimum conditions and the development of a standard protocol are critical during selection of a reliable method to determine its bioactivity. This paper uses quality control theory to validate a modified version of a method proposed by Charney and Tomarelli in 1947. The results obtained showed that using azocasein substrate bromelain had its optimum at 45°C and pH 9 (Glycine-NaOH 100 mM). We also quantified the limit of detection (LoD) and limit of quantification (LoQ) in the above-mentioned optimum (0.072 and 0.494 mg·mL−1 of azocasein, resp.) and a calibration curve that correlates optical density with the amount of substrate digested. In all analysed samples, we observed a significant decrease in response after storage (around 17%), which suggests its use must be immediately after preparation. Thus, the protocol presented in this paper offers a significant improvement, given that subjective definitions are commonly used in the literature and this simple mathematical approach makes it clear and concise. PMID:26925415

Analysis of abamectin residues in avocados by high-performance liquid chromatography with fluorescence detection.

PubMed

Hernández-Borges, Javier; Ravelo-Pérez, Lidia M; Hernández-Suárez, Estrella M; Carnero, Aurelio; Rodríguez-Delgado, Miguel Angel

2007-09-21

In this work an analytical method for the determination of abamectin residues in avocados is developed using high-performance liquid chromatography (HPLC) with fluorescence (FL) detection. A pre-column derivatization with trifluoroacetic anhydride (TFAA) and N-methylimidazole (NMIM) was carried out. The mobile phase consisted of water, methanol and acetonitrile (5:47.5:47.5 v/v/v) and was pumped at a rate of 1 mL/min (isocratic elution). The fluorescence detector was set at an excitation wavelength of 365 nm and an emission wavelength of 470 nm. Homogenized avocado samples were extracted twice with acetonitrile:water 8:2 (v/v) and cleaned using C(18) solid-phase extraction (SPE) cartridges. Recovery values were in the range 87-98% with RSD values lower than 13%. The limits of detection (LODs) and quantification (LOQs) of the whole method were 0.001 and 0.003 mg/kg, respectively. These values are lower than the maximum residue limit (MRL) established by the European Union (EU) and the Spanish legislation in avocado samples.

Applicability of the chymopapain gene used as endogenous reference gene for transgenic huanong no. 1 papaya detection.

PubMed

Guo, Jinchao; Yang, Litao; Liu, Xin; Zhang, Haibo; Qian, Bingjun; Zhang, Dabing

2009-08-12

The virus-resistant papaya (Carica papaya L.), Huanong no. 1, was the genetically modified (GM) fruit approved for growing in China in 2006. To implement the labeling regulation of GM papaya and its derivates, the development of papaya endogenous reference gene is very necessary for GM papaya detection. Herein, we reported one papaya specific gene, Chymopapain (CHY), as one suitable endogenous reference gene, used for GM papaya identification. Thereafter, we established the conventional and real-time quantitative PCR assays of the CHY gene. In the CHY conventional PCR assay, the limit of detection (LOD) was 25 copies of haploid papaya genome. In the CHY real-time quantitative PCR assay, both the LOD and the limit of quantification (LOQ) were as low as 12.5 copies of haploid papaya genome. Furthermore, we revealed the construct-specific sequence of Chinese GM papaya Huanong no. 1 and developed its conventional and quantitative PCR systems employing the CHY gene as endogenous reference gene. This work is useful for papaya specific identification and GM papaya detection.

Combination of QuEChERS and DLLME for GC-MS determination of pesticide residues in orange samples.

PubMed

Andraščíková, Mária; Hrouzková, Svetlana; Cunha, Sara C

2013-01-01

A new method combining QuEChERS (quick, easy, cheap, effective, rugged and safe) and DLLME (dispersive liquid-liquid microextraction) followed by gas chromatography-mass spectrometry with selected ion monitoring (SIM) was developed for the simultaneous determination of 19 pesticides from nine chemical groups exhibiting or suspected to exhibit endocrine-disrupting properties in orange samples. Acetonitrile extract obtained from QuEChERS extraction was used for DLLME as dispersive solvent and carbon tetrachloride as extractive solvent to increase the enrichment factor of the extraction procedure. The effect of several extraction parameters, such as volume extract achieved by the QuEChERS method and subsequently used for DLLME, selection of extractive solvent and its volume, was tested. Under optimum conditions, good linearity, satisfactory recoveries and repeatability were obtained. Limits of quantification (LOQs) achieved (ranging from 0.02 to 47 ng/g) were below the maximum residue limits established by the European Union. The proposed method was applied to the monitoring of pesticide residue levels in oranges commercialised in Portugal.

Rapid screening and quantification of residual pesticides and illegal adulterants in red wine by direct analysis in real time mass spectrometry.

PubMed

Guo, Tianyang; Fang, Pingping; Jiang, Juanjuan; Zhang, Feng; Yong, Wei; Liu, Jiahui; Dong, Yiyang

2016-11-04

A rapid method to screen and quantify multi-class analytic targets in red wine has been developed by direct analysis in real time (DART) coupled with triple quadruple tandem mass spectrometry (QqQ-MS). A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure was used for increasing analytical speed and reducing matrix effect, and the multiple reaction monitoring (MRM) in DART-MS/MS ensured accurate analysis. One bottle of wine containing 50 pesticides and 12 adulterants, i.e., preservatives, antioxidant, sweeteners, and azo dyes, could be totally determined less than 12min. This method exhibited proper linearity (R 2 ≥0.99) in the range of 1-1000ng/mL for pesticides and 10-5000ng/mL for adulterants. The limits of detection (LODs) were obtained in a 0.5-50ng/mL range for pesticides and 5-50ng/mL range for adulterants, and the limits of quantification (LOQs) were in a 1-100ng/mL range for pesticides and 10-250ng/mL range for adulterants. Three spiked levels for each analyte in wine were evaluated, and the recoveries were in a scope of 75-120%. The results demonstrated DART-MS/MS was a rapid and simple method, and could be applied to rapid analyze residual pesticides and illegal adulterants in a large quantities of red wine. Copyright © 2016 Elsevier B.V. All rights reserved.

Qualitative screening of veterinary anti-microbial agents in tissues, milk, and eggs of food-producing animals using liquid chromatography coupled with tandem mass spectrometry.

PubMed

Chen, Dongmei; Yu, Jie; Tao, Yanfei; Pan, Yuanhu; Xie, Shuyu; Huang, Lingli; Peng, Dapeng; Wang, Xu; Wang, Yulian; Liu, Zhenli; Yuan, Zonghui

2016-04-01

A method for the analysis of 120 drugs in animal derived food was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). These analytes belong to 12 families of veterinary anti-microbial agents (quinolones, macrolides, β-lactams, nitroimidazoles, sulfonamides, lincomycines, chloramphenicols, quinoxalines, tetracyclines, polypeptides, and antibacterial synergists) as well as other compounds not assigned to a particular drug family. The animal derived food samples include muscle and liver of swine, bovine, sheep, and chicken, as well as hen eggs and dairy milk. The sample preparation included ultrasound-assisted extraction (UAE) with acetonitrile-water and a final clean-up with auto solid-phase extraction (SPE) on HLB cartridges. The detection and quantification of 120 anti-microbial agents was performed using LC-MS/MS in positive and negative ion mode. The chromatographic separation was performed on a C18 column using acetonitrile and 0.1% formic acid as the mobile phase. The limit of detection (LOD) and limit of quantification (LOQ) of all drugs in food-producing animals were 0.5-3.0μg/kg and 1.5-10.0μg/kg, respectively. The developed method was successfully utilized to monitor real samples, which demonstrated that it is a simple, fast, and robust method, and could be used as a regulatory to screen for the presence of residues from veterinary anti-microbial drugs in animal-derived foods. Copyright © 2016 Elsevier B.V. All rights reserved.

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

PubMed

Zhu, Feng

2015-01-01

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

Comprehensive determination of flavouring additives and nicotine in e-cigarette refill solutions. Part I: Liquid chromatography-tandem mass spectrometry analysis.

PubMed

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

2017-10-13

Liquid chromatography-tandem mass spectrometry with electrospray ionization (HPLC-ESI-MS/MS) methods were developed for the simultaneous determination of 42 flavouring compounds and nicotine in liquids for e-cigarettes. The chromatographic separation was performed using an Ace ® Ultracore™ SuperC18™ (100×2.1mm, 2.5μm) column in both acidic and alkaline pH conditions to separate all the compounds. A simple "dilute & shoot" approach was used for the sample preparation. The method validation was performed by evaluating key analytical parameters such as linearity, accuracy, selectivity, precision, limit of detection (LOD) and limit of quantification (LOQ). The calibration curves showed good linearity within the specific ranges for the investigated compounds with correlation coefficients greater than 0.990 in each case. The recovery for all the investigated compounds varied from 89% to 110%. The intra- and inter-day precision were within the acceptable limits (±15%) at all tested concentrations. The applicability of the methods was examined by analysing 25 liquid samples from e-cigarettes commercially available on the Polish market. Copyright © 2017 Elsevier B.V. All rights reserved.

Analysis of adulterants in a traditional herbal medicinal product using liquid chromatography-mass spectrometry-mass spectrometry.

PubMed

Lau, Aik-Jiang; Holmes, Michael J; Woo, Soo-On; Koh, Hwee-Ling

2003-02-26

Adulterations with synthetic drugs are common problems with herbal medicine and this can potentially cause serious adverse effects. It is therefore important to determine the presence of synthetic drugs in herbal medicine to ensure patients' safety. The objective of this study was to develop sensitive and specific methods to analyse phenylbutazone, caffeine and oxyphenbutazone present in a traditional Indonesian herbal product. Liquid chromatography-mass spectrometry-mass spectrometry (LC-MS-MS) methods in the selected reaction-monitoring (SRM) mode were developed. It was found that the sample contained 0.53% w/w (n=3, RSD=7.56%) phenylbutazone and 0.04% w/w (n=3, RSD=8.39%) caffeine. This corresponded to 43.17 mg phenylbutazone and 3.23 mg caffeine in each sachet of powder. The methods were validated for linearity, precision, accuracy, LOD and LOQ. LOD and LOQ were found to be 3.69 and 12.29 ng/ml, respectively for phenylbutazone. For caffeine, the LOD and LOQ were 0.84 and 2.80 ng/ml, respectively. Oxyphenbutazone in the sample was found to be present at a level below the quantification level of 10.2 ng/ml. With better methods developed for analysis of adulterants in herbal medicine, the quality and safety of these medicines can be better controlled and regulated to ensure patients' safety.

Fast determination of four polar contaminants in soy nutraceutical products by liquid chromatography coupled to tandem mass spectrometry.

PubMed

Domingos Alves, Renata; Romero-González, Roberto; López-Ruiz, Rosalía; Jiménez-Medina, M L; Garrido Frenich, Antonia

2016-11-01

An analytical method based on a modified QuPPe (quick polar pesticide) extraction procedure coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was evaluated for the determination of four polar compounds (chlorate, fosetyl-Al, maleic hydrazide, and perchlorate) in nutraceutical products obtained from soy. Experimental conditions including extraction such as solvent, acidification, time, and clean-up sorbents were varied. Acidified acetonitrile (1 % formic acid, v/v) was used as extraction solvent instead of methanol (conventional QuPPe), which provides a doughy mixture which cannot be injected into the LC. Clean-up or derivatization steps were avoided. For analysis, several stationary phases were evaluated and Hypercarb (porous graphitic carbon) provided the best results. The optimized method was validated and recoveries ranged between 46 and 119 %, and correction factors can be used for quantification purposes bearing in mind that inter-day precision was equal to or lower than 17 %. Limits of quantification (LOQs) ranged from 4 to 100 μg kg -1 . Soy-based nutraceutical products were analyzed and chlorate was detected in five samples at concentrations between 63 and 1642 μg kg -1 . Graphical Abstract Analysis of polar compounds in soy-based nutraceutical products.

Rapid Method for the Determination of 5-Hydroxymethylfurfural and Levulinic Acid Using a Double-Wavelength UV Spectroscopy

PubMed Central

Xue, Guoxin

2013-01-01

This study reports on a rapid method for the determination of levulinic acid (LA) and 5-hydroxymethylfurfural (HMF) in acid hydrolyze system of glucose based on UV spectroscopy. It was found that HMF and LA have a maximum absorption at the wavelengths of 284 nm and 266 nm, respectively, in a water medium, and the absorptions of HMF and LA at 284 nm and 266 nm follow Beer's law very well. However, it was found that a major spectral interference species will arise in the quantification of HMF and LA; nonetheless, this interference can be eliminated through the absorption treatment of charcoal. Therefore, both HMF and LA can be quantified with a double-wavelength technique. The repeatability of the method had a relative standard deviation of less than 4.47% for HMF and 2.25% for LA; the limit of quantification (LOQ) was 0.017 mmol/L for HMF and 4.68 mmol/L for LA, and the recovery ranged from 88% to 116% for HMF and from 94% to 105% for LA. The present method is simple, rapid, and accurate. It is suitable to use in the research of the preparation of HMF and LA in biorefinery area. PMID:24228006

Development and validation of a LC-ESI-MS/MS method for the determination of phenolic compounds in honeydew honeys with the diluted-and-shoot approach.

PubMed

Seraglio, Siluana Katia Tischer; Valese, Andressa Camargo; Daguer, Heitor; Bergamo, Greici; Azevedo, Mônia Stremel; Gonzaga, Luciano Valdemiro; Fett, Roseane; Costa, Ana Carolina Oliveira

2016-09-01

A simple, reproducible and sensitive method has been optimized and validated for simultaneous determination of 32 phenolic compounds in bracatinga (Mimosa scabrella Benth.) with the diluted-and-shoot approach, without the need of any additional clean-up steps. It has been based on high performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry and electrospray ionization (HPLC-ESI-MS/MS). The chromatography conditions were optimized, and due to the selectivity provided by MRM monitoring, LC separation required only 9min. The developed method was validated on the basis of Eurachem and European Commission Decision 2002/657/EC guidelines. Mean recoveries ranged from 70.4 to 110%. Intra-day and inter-day precision with RSD (relative standard deviations) from 0.14 to 18.9% and 0.34 to 20.0%, respectively were achieved. Limits of detection (LOD) and quantification (LOQ) ranged from 0.03 to 3.20μgL -1 and 0.20-12.8μgL -1 . Finally, the method was applied to samples and 20 phenolic compounds were quantified in all the samples analyzed, representing a contribution to the characterization and quantification of phenolic compounds from bracatinga (M. scabrella Bentham) honeydew honey. Copyright © 2016 Elsevier Ltd. All rights reserved.

Validation of a method to monitor the occurrence of 20 relevant pharmaceuticals and personal care products in 167 bottled waters.

PubMed

Lardy-Fontan, Sophie; Le Diouron, Véronique; Drouin, Catherine; Lalere, Béatrice; Vaslin-Reimann, Sophie; Dauchy, Xavier; Rosin, Christophe

2017-06-01

Research on emerging substances in drinking water presents major interest and the possibility of trace contamination has seen increasing concern from the scientific community and the public authorities. More particularly, residues of pharmaceuticals and personal care products (PPCPs) in bottled water are a very important issue due to societal concerns and potential media impact. In this context, it has become necessary to carry out reliable monitoring. This requires measurements of high quality with demonstration of accuracy and well-defined uncertainty. In this study, 20 pharmaceutical compounds were targeted for the first time in 167 bottled waters from France and other European countries. An isotope dilution-solid phase extraction-liquid chromatography mass spectrometry method, together with stringent quality control and quality assurance protocols, was developed and validated according to French mandatory standards. Recoveries between 87% and 112% were obtained with coefficient of variation below 20%. Operational limits of quantification (LOQ) were comprised between 5 and 30ngL -1 . Expanded uncertainties (k=2) ranged between 16% and 43% and were below 35% for half of the compounds. The survey showed only four positive quantifications, thereby highlighting the rarity of contamination. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimized, Fast-Throughput UHPLC-DAD Based Method for Carotenoid Quantification in Spinach, Serum, Chylomicrons, and Feces.

PubMed

Eriksen, Jane N; Madsen, Pia L; Dragsted, Lars O; Arrigoni, Eva

2017-02-01

An improved UHPLC-DAD-based method was developed and validated for quantification of major carotenoids present in spinach, serum, chylomicrons, and feces. Separation was achieved with gradient elution within 12.5 min for six dietary carotenoids and the internal standard, echinenone. The proposed method provides, for all standard components, resolution > 1.1, linearity covering the target range (R > 0.99), LOQ < 0.035 mg/L, and intraday and interday RSDs < 2 and 10%, respectively. Suitability of the method was tested on biological matrices. Method precision (RSD%) for carotenoid quantification in serum, chylomicrons, and feces was below 10% for intra- and interday analysis, except for lycopene. Method accuracy was consistent with mean recoveries ranging from 78.8 to 96.9% and from 57.2 to 96.9% for all carotenoids, except for lycopene, in serum and feces, respectively. Additionally, an interlaboratory validation study on spinach at two institutions showed no significant differences in lutein or β-carotene content, when evaluated on four occasions.

Occurrence of Aflatoxins in Selected Processed Foods from Pakistan

PubMed Central

Mushtaq, Muhammad; Sultana, Bushra; Anwar, Farooq; Khan, Muhammad Zargham; Ashrafuzzaman, Muhammad

2012-01-01

A total of 125 (ready to eat) processed food samples (70 intended for infant and 55 for adult intake) belonging to 20 different food categories were analyzed for aflatoxins contamination using Reverse Phase High Performance Liquid Chromatography (RP-HPLC) with fluorescent detection. A solvent mixture of acetonitrile-water was used for the extraction followed by immunoaffinity clean-up to enhance sensitivity of the method. The limit of detection (LOD) (0.01–0.02 ng·g−1) and limit of quantification (LOQ) (0.02 ng·g−1) was established for aflatoxins based on signal to noise ratio of 3:1 and 10:1, respectively. Of the processed food samples tested, 38% were contaminated with four types of aflatoxins, i.e., AFB1 (0.02–1.24 μg·kg−1), AFB2 (0.02–0.37 μg·kg−1), AFG1 (0.25–2.7 μg·kg−1) and AFG2 (0.21–1.3 μg·kg−1). In addition, the results showed that 21% of the processed foods intended for infants contained AFB1 levels higher than the European Union permissible limits (0.1 μg·kg−1), while all of those intended for adult consumption had aflatoxin contamination levels within the permitted limits. PMID:22942705

Multi-residue method for determination of 58 pesticides, pharmaceuticals and personal care products in water using solvent demulsification dispersive liquid-liquid microextraction combined with liquid chromatography-tandem mass spectrometry.

PubMed

Caldas, Sergiane Souza; Rombaldi, Caroline; Arias, Jean Lucas de Oliveira; Marube, Liziane Cardoso; Primel, Ednei Gilberto

2016-01-01

A rapid and efficient sample pretreatment using solvent-based de-emulsification dispersive liquid-liquid microextraction (SD-DLLME) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was studied for the extraction of 58 pharmaceuticals and personal care products (PPCPs) and pesticides from water samples. Type and volume of extraction and disperser solvents, pH, salt addition, amount of salt and type of demulsification solvent were evaluated. Limits of quantification (LOQ) in the range from 0.0125 to 1.25 µg L(-1) were reached, and linearity was in the range from the LOQ of each compound to 25 μg L(-1). Recoveries ranged from 60% to 120% for 84% of the compounds, with relative standard deviations lower than 29%. The proposed method demonstrated, for the first time, that sample preparation by SD-DLLME with determination by LC-MS/MS can be successfully used for the simultaneous extraction of 32 pesticides and 26 PPCPs from water samples. The entire procedure, including the extraction of 58 organic compounds from the aqueous sample solution and the breaking up of the emulsion after extraction with water, rather than with an organic solvent, was environmentally friendly. In addition, this technique was less expensive and faster than traditional techniques. Finally, the analytical method under study was successfully applied to the analysis of all 58 pesticides and PPCPs in surface water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Development and validation of a UV-spectrophotometric method for the determination of pheniramine maleate and its stability studies

NASA Astrophysics Data System (ADS)

Raghu, M. S.; Basavaiah, K.; Ramesh, P. J.; Abdulrahman, Sameer A. M.; Vinay, K. B.

2012-03-01

A sensitive, precise, and cost-effective UV-spectrophotometric method is described for the determination of pheniramine maleate (PAM) in bulk drug and tablets. The method is based on the measurement of absorbance of a PAM solution in 0.1 N HCl at 264 nm. As per the International Conference on Harmonization (ICH) guidelines, the method was validated for linearity, accuracy, precision, limits of detection (LOD) and quantification (LOQ), and robustness and ruggedness. A linear relationship between absorbance and concentration of PAM in the range of 2-40 μg/ml with a correlation coefficient (r) of 0.9998 was obtained. The LOD and LOQ values were found to be 0.18 and 0.39 μg/ml PAM, respectively. The precision of the method was satisfactory: the value of relative standard deviation (RSD) did not exceed 3.47%. The proposed method was applied successfully to the determination of PAM in tablets with good accuracy and precision. Percentages of the label claims ranged from 101.8 to 102.01% with the standard deviation (SD) from 0.64 to 0.72%. The accuracy of the method was further ascertained by recovery studies via a standard addition procedure. In addition, the forced degradation of PAM was conducted in accordance with the ICH guidelines. Acidic and basic hydrolysis, thermal stress, peroxide, and photolytic degradation were used to assess the stability-indicating power of the method. A substantial degradation was observed during oxidative and alkaline degradations. No degradation was observed under other stress conditions.

Indirect Determination of Pentaerythritol Tetranitrate (PETN) with a gold nanoparticles-based colorimetric sensor.

PubMed

Üzer, Ayşem; Yalçın, Uğur; Can, Ziya; Erçağ, Erol; Apak, Reşat

2017-12-01

Pentaerythritol tetranitrate (PETN) is the nitrate ester of pentaerythritol, used as an energetic and filling material for military and civilian purposes and rarely for terrorist actions. As there is no reliable nano-colorimetric method for PETN assay, we developed an indirect method based on the determination of nitrite, obtained by reduction of nitrate derived from the alkaline hydrolysis of PETN with H 2 O 2 . We colorimetrically determined the final product, nitrite, by both conventional Griess reaction and a recently developed gold nanoparticle-4-aminothiophenol-N-(1-naphthyl)-ethylenediamine (AuNP-4-ATP+NED) method. Nitramines (RDX and HMX), if present, could be degraded by alkaline hydrolysis, without affecting PETN. The analytical performance characteristics of the developed assays as molar absorptivity (ε), limits of detection (LOD) and quantification (LOQ) were: ɛ=1.06×10 5 L mol -1 cm -1 , LOD=0.03mgL -1 and LOQ=0.11mgL -1 for indirect Griess method; ɛ=1.9×10 4 Lmol -1 cm -1 ; LOD=0.12mgL -1 and LOQ=0.4mgL -1 for AuNP-4-ATP+NED method. Both methods were applied to a 1:1 (w/w) mixture of PETN and TNT (corresponding to the composition of military explosive 'Pentolite'). In order to eliminate the interference from TNT, the Meisenheimer anion of TNT formed in alkaline medium was retained on a strongly basic anion exchange resin column. As PETN had a very low solubility in water, common soil ions could be eliminated by prewashing the sample with water, or in acetone-water mixtures, Ca 2+ , K + , Cl - , SO 4 2- , and NO 3 - could be tolerated at equal (1:1) mass ratios. Soil nitrates and nitrites, at a mass ratio of 50:1, could be separated from PETN with the aid of their insolubilities in acetone and of their retention affinity toward a strongly basic anion-exchange resin. The developed method was statistically validated against a reference GC-MS method. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of alcohol sulfates in wastewater treatment plant influents and effluents by gas chromatography-mass spectrometry.

PubMed

Fernández-Ramos, C; Ballesteros, O; Blanc, R; Zafra-Gómez, A; Jiménez-Díaz, I; Navalón, A; Vílchez, J L

2012-08-30

In the present paper, we developed an accurate method for the analysis of alcohol sulfates (AS) in wastewater samples from wastewater treatment plant (WWTP) influents and effluents. Although many methodologies have been published in the literature concerning the study of anionic surfactants in environmental samples, at present, the number of analytical methodologies that focus in the determination of AS by gas chromatography in the different environmental compartments is limited. The reason for this is that gas chromatography-mass spectrometry (GC-MS) technique requires a previous hydrolysis reaction followed by derivatization reactions. In the present work, we proposed a new procedure in which the hydrolysis and derivatization reactions take place in one single step and AS are directly converted to trimethylsilyl derivatives. The main factors affecting solid-phase extraction (SPE), hydrolysis/derivatization and GC-MS procedures were accurately optimised. Quantification of the target compounds was performed by using GC-MS in selected ion monitoring (SIM) mode. The limits of detection (LOD) obtained ranged from 0.2 to 0.3 μg L(-1), and limits of quantification (LOQ) from 0.5 to 1.0 μg L(-1), while inter- and intra-day variability was under 5%. A recovery assay was also carried out. Recovery rates for homologues in spiked samples ranged from 96 to 103%. The proposed method was successfully applied for the determination of anionic surfactants in wastewater samples from one WWTP located in Granada (Spain). Concentration levels for the homologues up to 39.4 μg L(-1) in influent and up to 8.1 μg L(-1) in effluent wastewater samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Rapid determination of chlormequat in meat by dispersive solid-phase extraction and hydrophilic interaction liquid chromatography (HILIC)-electrospray tandem mass spectrometry.

PubMed

Li, Chunmei; Jin, Fen; Yu, Zhiyong; Qi, Yamei; Shi, Xiaomei; Wang, Miao; Shao, Hua; Jin, Maojun; Wang, Jing; Yang, Mingqi

2012-07-11

A rapid method for analyzing trace levels of chlormequat (CQ) in meat samples by hydrophilic interaction liquid chromatography (HILIC)-electrospray tandem mass spectrometry was developed. The samples were extracted with acetonitrile, followed by a rapid cleanup through a dispersive solid-phase extraction (DSPE) technique with octadecyl (C18) DSPE sorbents. The chromatographic separation was achieved within 6 min using a HILIC column with 10 mM ammonium acetate and 0.1% (v/v) formic acid in water/acetonitrile (v/v, 40:60) as the mobile phase. Quantification was performed using a matrix-matched calibration curve, which was linear in the range of the 0.05-100 μg/L. The limit of detection (LOD) was estimated at 0.03 μg/kg for CQ on the basis of a peak to peak signal noise (S/N = 3). The limit of quantification (LOQ) was 0.1 μg/kg on the basis of the lowest spiked concentration with suitable precision and accuracy. The average recovery of CQ in spiked meat samples was 86.4-94.7% at 2, 20, and 200 μg/kg. Finally, this method was applied to determine CQ in the livestock and poultry meats purchased from markets in Beijing in 2011. CQ was detected in all 12 samples, and the concentration was 0.4-636.0 μg/kg. Concentrations in a chicken sample (636.0 μg/kg) and a goat meat sample (486.0 μg/kg) were found to be 15.9 and 2.43 times the corresponding Codex maximum residue limits, respectively.

Occurrence and removal of estrogens, progesterone and testosterone in three constructed wetlands treating municipal sewage in the Czech Republic.

PubMed

Vymazal, Jan; Březinová, Tereza; Koželuh, Milan

2015-12-01

Estrogenic hormones, progesterone and testosterone are endocrine-disrupting chemicals and their presence in aquatic environments represents a potentially adverse environmental and public health impact. There is a considerable amount of information about removal of estrogens, progesterone and testosterone in conventional wastewater treatment plants, namely activated sludge systems. However, the information about removal of these compounds in constructed wetlands is very limited. Three constructed wetlands with horizontal subsurface flow in the Czech Republic have been selected to evaluate removal of estrogens (estrone, estriol, 17β-estradiol, 17α-ethinylestradiol), testosterone and progesterone. Monitored constructed wetlands for 100, 150 and 200 PE have been in operation for more than 10 years and all systems exhibit very high treatment efficiency for organics and suspended solids. The results indicate that removal of all estrogens, progesterone and testosterone was high and only estrone was found in the outflow from one constructed wetland in concentrations above the limit of quantification 1 ng l(-1). The limits of quantification for other estrogens, i.e., 10 ng l(-1) for estriol, 1 ng l(-1) for 17β-estradiol and 2 ng l(-1) for 17α-ethinylestradiol were not exceeded in the outflow of all monitored constructed wetlands. Also, for progesterone and testosterone, all outflow concentrations were below the LOQ of 0.5 ng l(-1). The results indicated that constructed wetlands with horizontal subsurface flow are a promising technology for elimination of estrogens, progesterone and testosterone from municipal sewage but more information is needed to confirm this finding. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous analysis of organochlorine pesticides and polychlorinated biphenyls in air samples by using accelerated solvent extraction (ASE) and solid-phase micro-extraction (SPME) coupled to gas chromatography dual electron capture detection.

PubMed

Mokbel, Haifaa; Al Dine, Enaam Jamal; Elmoll, Ahmad; Liaud, Céline; Millet, Maurice

2016-04-01

An analytical method associating accelerated solvent extraction (ASE) and solid-phase micro-extraction (SPME) in immersion mode combined with gas chromatography dual electrons capture detectors (SPME-GC-2ECD) has been developed and studied for the simultaneous determination of 19 organochlorine pesticides (OCPs) and 22 polychlorinated biphenyls (PCBs) in air samples (active and XAD-2 passive samplers). Samples were extracted with ASE with acetonitrile using the following conditions: temperature, 150 °C; pressure, 1500 psi; static, 15 min; cycles, 3; purge, 300 s; flush, 100 %. Extracts were reduced to 1 mL, and 500 μL of this extract, filled with deionised water, was subject to SPME extraction. Experimental results indicated that the proposed method attained the best extraction efficiency under the optimised conditions: extraction of PCB-OCP mixture using 100-μm PDMS fibre at 80 °C for 40 min with no addition of salt. The performance of the proposed ASE-SPME-GC-2ECD methodology with respect to linearity, limit of quantification and detection was evaluated by spiking of XAD-2 resin with target compounds. The regression coefficient (R (2)) of most compounds was found to be high of 0.99. limits of detection (LODs) are between 0.02 and 4.90 ng m(-3), and limits of quantification (LOQs) are between 0.05 and 9.12 ng m(-3) and between 0.2 and 49 ng/sampler and 0.52 and 91 ng/sampler, respectively, for XAD-2 passive samplers. Finally, a developed procedure was applied to determine selected PCBs and OCPs in the atmosphere.

Application of statistical experimental design to the optimisation of microextraction by packed sorbent for the analysis of nonsteroidal anti-inflammatory drugs in human urine by ultra-high pressure liquid chromatography.

PubMed

Magiera, Sylwia; Gülmez, Şefika; Michalik, Aleksandra; Baranowska, Irena

2013-08-23

A new approach based on microextraction by packed sorbent (MEPS) and a reversed-phase ultra-high pressure liquid chromatography (UHPLC) method was developed and validated for the determination and quantification of nonsteroidal anti-inflammatory drugs (NSAIDs) (acetylsalicylic acid, ketoprofen, diclofenac, naproxen and ibuprofen) in human urine. The important factors that could influence the extraction were previously screened using the Plackett-Burman design approach. The optimal MEPS extraction conditions were obtained using C18 phase as a sorbent, small sample volume (20μL) and a short time period (approximately 5min) for the entire sample preparation step. The analytes were separated on a core-shell column (Poroshell 120 EC-C18; 100mm×3.0mm; 2.7μm) using a binary mobile phase composed of aqueous 0.1% trifluoroacetic acid and acetonitrile in the gradient elution mode (4.5min of analysis time). The analytical method was fully validated based on linearity, limits of detection (LOD), limits of quantification (LOQ), inter- and intra-day precision and accuracy, and extraction yield. Under optimised conditions, excellent linearity (R(2)>0.9991), limits of detection (1.07-16.2ngmL(-1)) and precision (0.503-9.15% RSD) were observed for the target drugs. The average absolute recoveries of the analysed compounds extracted from the urine samples were 89.4-107%. The proposed method was also applied to the analysis of NSAIDs in human urine. The new approach offers an attractive alternative for the analysis of selected drugs from urine samples, providing several advantages including fewer sample preparation steps, faster sample throughput and ease of performance compared to traditional methodologies. Copyright © 2013 Elsevier B.V. All rights reserved.

A multi-residue method for pesticides analysis in green coffee beans using gas chromatography-negative chemical ionization mass spectrometry in selective ion monitoring mode.

PubMed

Pizzutti, Ionara R; de Kok, Andre; Dickow Cardoso, Carmem; Reichert, Bárbara; de Kroon, Marijke; Wind, Wouter; Weber Righi, Laís; Caiel da Silva, Rosselei

2012-08-17

In this study, a new gas chromatography-mass spectrometry (GC-MS) method, using the very selective negative chemical ionization (NCI) mode, was developed and applied in combination with a modified acetonitrile-based extraction method (QuEChERS) for the analysis of a large number of pesticide residues (51 pesticides, including isomers and degradation products) in green coffee beans. A previously developed integrated sample homogenization and extraction method for both pesticides and mycotoxins analysis was used. An homogeneous slurry of green milled coffee beans and water (ratio 1:4, w/w) was prepared and extracted with acetonitrile/acetic acid (1%), followed by magnesium sulfate addition for phase separation. Aliquots from this extract could be used directly for LC-MS/MS analysis of mycotoxins and LC-amenable pesticides. For GC-MS analysis, a further clean-up was necessary. C18- and PSA-bonded silica were tested as dispersive solid-phase extraction (d-SPE) sorbents, separate and as a mixture, and the best results were obtained using C18-bonded silica. For the optimal sensitivity and selectivity, GC-MS detection in the NCI-selected ion monitoring (SIM) mode had to be used to allow the fast analysis of the difficult coffee bean matrix. The validation was performed by analyzing recovery samples at three different spike concentrations, 10, 20 and 50 μg kg(-1), with 6 replicates (n=6) at each concentration. Linearity (r(2)) of calibration curves, estimated instrument and method limits of detection and limits of quantification (LOD(i), LOD(m), LOQ(i) and LOQ(m), respectively), accuracy (as recovery %), precision (as RSD%) and matrix effects (%) were determined for each individual pesticide. From the 51 analytes (42 parent pesticides, 4 isomers and 5 degradation products) determined by GC-MS (NCI-SIM), approximately 76% showed average recoveries between 70-120% and 75% and RSD ≤ 20% at the lowest spike concentration of 10 μg kg(-1), the target method LOQ. For the spike concentrations of 20 and 50 μg kg(-1), the recoveries and RSDs were even better. The validated LOQ(m) was 10, 20 and 50 μg kg(-1) for respectively 33, 3 and 6 of the analytes studied. For five compounds, the European Union method performance requirements for the validation of a quantitative method (average recoveries between 70-120% and repeatability RSD ≤ 20%) were not achieved and 4 problematic pesticides (captan, captafol, folpet and dicofol) could not be detected as their parent compound, but only via their degradation products. Although the matrix effect (matrix-enhanced detector response) was high for all pesticides studied, the matrix interference was minimal, due to the high selectivity obtained with the GC-NCI-MS detection. Matrix-matched calibration for applying the method in routine analysis is recommended for reliable quantitative results. Copyright © 2012 Elsevier B.V. All rights reserved.

Study of vortex-assisted MSPD and LC-MS/MS using alternative solid supports for pharmaceutical extraction from marketed fish.

PubMed

Hertzog, Gabriel I; Soares, Karina L; Caldas, Sergiane S; Primel, Ednei G

2015-06-01

A procedure based on vortex-assisted matrix solid-phase dispersion (MSPD) for the extraction of 15 pharmaceuticals from fish samples with determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was validated. Florisil, C18, diatomaceous earth, chitin, and chitosan were evaluated as solid supports. Best results were obtained with 0.5 g of diatomaceous earth, 0.5 g of sodium sulfate, and 5 mL of methanol. Analytical recoveries ranged from 58 to 128 % with relative standard deviation (RSD) lower than 15 %. Limit of quantification (LOQ) values for the 15 compounds ranged from 5 to 1000 ng g(-1). The method under investigation has shown to be a simple and fast extraction tool with minimum instrumentation and low amount of reagent, resulting in method low cost. Besides, alternative materials, such as chitin and chitosan, which were applied to the dispersion step for the first time, were found to be interesting alternatives.

Cathodic stripping voltammetric determination of arsenic in sugarcane brandy at a modified carbon nanotube paste electrode.

PubMed

Teixeira, Meryene C; Tavares, Elisângela de F L; Saczk, Adelir A; Okumura, Leonardo L; Cardoso, Maria das Graças; Magriotis, Zuy M; de Oliveira, Marcelo F

2014-07-01

We have developed an eletroanalytical method that employs Cu(2+) solutions to determine arsenic in sugarcane brandy using an electrode consisting of carbon paste modified with carbon nanotubes (CNTPE) and polymeric resins. We used linear sweep (LSV) and differential-pulse (DPV) voltammetry with cathodic stripping for CNTPE containing mineral oil or silicone as binder. The analytical curves were linear from 30 to 110μgL(-1) and from 10 to 110μgL(-1) for LSV and DPV, respectively. The limits of detection (L.O.D.) and quantification (L.O.Q.) of CNTPE were 10.3 and 34.5μgL(-1) for mineral oil and 3.4 and 11.2μgL(-1) for silicone. We applied this method to determine arsenic in five commercial sugarcane brandy samples. The results agreed well with those obtained by hydride generation combined with atomic absorption spectrometry (HG AAS). Copyright © 2014 Elsevier Ltd. All rights reserved.

High resolution mass spectrometry studies of sulforaphane and indole-3-carbinol in broccoli.

PubMed

Kokotou, Maroula G; Revelou, Panagiota-Kyriaki; Pappas, Christos; Constantinou-Kokotou, Violetta

2017-12-15

Broccoli is a rich source of bioactive compounds. Among them, sulforaphane and indole-3-carbinol have attracted a lot of attention, since their consumption is associated with reduced risk of cancer. In this work, the development of an efficient and direct method for the simultaneous determination of sulforaphane and indole-3-carbinol in broccoli using UPLC-HRMS/MS is described. The correlation coefficient, and limits of detection (LOD) and quantification (LOQ) were 0.993, 0.77mg/L and 2.35mg/L for sulforaphane and 0.997, 0.42mg/L, 1.29mg/L for indole-3-carbinol, respectively. The content of sulforaphane and indole-3-carbinol varied between 72±9-304±2mg and 77±1-117±3mg per 100g of fresh florets, respectively. Taking into consideration the differences in cultivar, geography, season and environmental factors, the results agreed with values published in the literature using other techniques. Copyright © 2017 Elsevier Ltd. All rights reserved.

Glassy carbon electrodes sequentially modified by cysteamine-capped gold nanoparticles and poly(amidoamine) dendrimers generation 4.5 for detecting uric acid in human serum without ascorbic acid interference.

PubMed

Ramírez-Segovia, A S; Banda-Alemán, J A; Gutiérrez-Granados, S; Rodríguez, A; Rodríguez, F J; Godínez, Luis A; Bustos, E; Manríquez, J

2014-02-17

Glassy carbon electrodes (GCE) were sequentially modified by cysteamine-capped gold nanoparticles (AuNp@cysteamine) and PAMAM dendrimers generation 4.5 bearing 128-COOH peripheral groups (GCE/AuNp@cysteamine/PAMAM), in order to explore their capabilities as electrochemical detectors of uric acid (UA) in human serum samples at pH 2. The results showed that concentrations of UA detected by cyclic voltammetry with GCE/AuNp@cysteamine/PAMAM were comparable (deviation <±10%; limits of detection (LOD) and quantification (LOQ) were 1.7×10(-4) and 5.8×10(-4) mg dL(-1), respectively) to those concentrations obtained using the uricase-based enzymatic-colorimetric method. It was also observed that the presence of dendrimers in the GCE/AuNp@cysteamine/PAMAM system minimizes ascorbic acid (AA) interference during UA oxidation, thus improving the electrocatalytic activity of the gold nanoparticles. Copyright © 2013 Elsevier B.V. All rights reserved.

Residue analysis of fipronil and difenoconazole in okra by liquid chromatography tandem mass spectrometry and their food safety evaluation.

PubMed

Hingmire, Sandip; Oulkar, Dasharath P; Utture, Sagar C; Ahammed Shabeer, T P; Banerjee, Kaushik

2015-06-01

A liquid chromatography tandem mass spectrometry (LC-MS/MS) based method is reported for simultaneous analysis of fipronil (plus its metabolites) and difenoconazole residues in okra. The sample preparation method involving extraction with ethyl acetate provided 80-107% recoveries for both the pesticides with precision RSD within 4-17% estimated at the limits of quantification (LOQ, fipronil=1ngg(-1), difenoconazole=5ngg(-1)) and higher fortification levels. In field, both the pesticides dissipated with half-life of 2.5days. The estimated pre-harvest intervals (PHI) for fipronil and difenoconazole were 15 and 19.5days, and 4 and 6.5days at single and double dose of field applications, respectively. Decontamination of incurred residues by washing and different cooking treatments was quite efficient in minimizing the residue load of both the chemicals. Okra samples harvested after the estimated PHIs were found safe for human consumption. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

PubMed

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

2013-01-01

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

Fluorescent carbon quantum dot hydrogels for direct determination of silver ions.

PubMed

Cayuela, A; Soriano, M L; Kennedy, S R; Steed, J W; Valcárcel, M

2016-05-01

The paper reports for the first time the direct determination of silver ion (Ag(+)) using luminescent Carbon Quantum Dot hydrogels (CQDGs). Carbon Quantum Dots (CQDs) with different superficial moieties (passivate-CQDs with carboxylic groups, thiol-CQDs and amine-CQDs) were used to prepare hybrid gels using a low molecular weight hydrogelator (LMWG). The use of the gels results in considerable fluorescence enhancement and also markedly influences selectivity. The most selective CQDG system for Ag(+) ion detection proved to be those containing carboxylic groups onto their surface. The selectivity towards Ag(+) ions is possibly due to its flexible coordination sphere compared with other metal ions. This fluorescent sensing platform is based on the strong Ag-O interaction which can quench the photoluminescence of passivate-CQDs (p-CQDs) through charge transfer. The limit of detection (LOD) and quantification (LOQ) of the proposed method were 0.55 and 1.83µgmL(-1), respectively, being applied in river water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of an analytical methodology using QuEChERS and GC-SQ/MS for the investigation of the level of pesticide residues in Brazilian melons.

PubMed

da Silva Sousa, Jonas; de Castro, Rubens Carius; de Albuquerque Andrade, Gilliane; Lima, Cleidiane Gomes; Lima, Lucélia Kátia; Milhome, Maria Aparecida Liberato; do Nascimento, Ronaldo Ferreira

2013-12-01

A multiresidue method based on the sample preparation by modified QuEChERS and detection by gas chromatography coupled to single quadruple mass spectrometers (GC-SQ/MS) was used for the analysis of 35 multiclass pesticides in melons (Cucumis melo inodorus) produced in Ceara-Brazil. The rates of recovery for pesticides studied were satisfactory (except for the etridiazole), ranging from 85% to 117% with a relative standard deviation (RSD) of less than 15%, at concentrations between 0.05 and 0.20 mg kg(-1). The limit of quantification (LOQ) for most compounds was below the MRLs established in Brazil. The combined relative uncertainty (Uc) and expanded uncertainty (Ue) was determined using repeatability, recovery and calibration curves data for each pesticide. Analysis of commercial melons samples revealed the presence of pesticides bifenthrin and imazalil at levels below the MRLs established by ANVISA, EU and USEPA. Copyright © 2013 Elsevier Ltd. All rights reserved.

Method Development for Pesticide Residue Analysis in Farmland Soil using High Perfomance Liquid Chromatography

NASA Astrophysics Data System (ADS)

Theresia Djue Tea, Marselina; Sabarudin, Akhmad; Sulistyarti, Hermin

2018-01-01

A method for the determination of diazinon and chlorantraniliprole in soil samples has been developed. The analyte was extracted with acetonitrile from farmland soil sample. Determination and quantification of diazinon and chlorantraniliprole were perfomed by high perfomance liquid chromatography (HPLC) with an UV detector. Several parameters of HPLC method were optimized with respect to sensitivity, high resolution of separation, and accurate determination of diazinon and chlorantraniliprole. Optimum conditions for the separation of two pesticides were eluent composition of acetonitrile:water ratio of 60:40, 0.4 mL/min of flow rate, and 220 nm of wavelength. Under the optimum conditions, diazinon linearity was in the range from 1-25 ppm with R2 of 0.9976, 1.19 mgL-1 LOD, and 3.98 mgL-1 LOQ; while the linearity of chlorantraniliprole was in the range from 0.2-5 mgL-1 with R2 of 0.9972, 0.39 mgL-1 LOD, and 1.29 mgL-1 LOQ. When the method was applied to the soil sample, both pesticides showed acceptable recoveries for real sample of more than 85%: thus, the developed method meets the validation requirement. Under this developed method, the concentrations of both pesticides in the soil samples were below the LOD and LOQ (0.577 mgL-1 for diazinon and 0.007 mgL-1 for chlorantraniliprole). Therefore, it can be concluded that the soil samples used in this study have neither diazinon nor chlorantraniliprole.

Comparison of NIR chemical imaging with conventional NIR, Raman and ATR-IR spectroscopy for quantification of furosemide crystal polymorphs in ternary powder mixtures.

PubMed

Schönbichler, S A; Bittner, L K H; Weiss, A K H; Griesser, U J; Pallua, J D; Huck, C W

2013-08-01

The aim of this study was to evaluate the ability of near-infrared chemical imaging (NIR-CI), near-infrared (NIR), Raman and attenuated-total-reflectance infrared (ATR-IR) spectroscopy to quantify three polymorphic forms (I, II, III) of furosemide in ternary powder mixtures. For this purpose, partial least-squares (PLS) regression models were developed, and different data preprocessing algorithms such as normalization, standard normal variate (SNV), multiplicative scatter correction (MSC) and 1st to 3rd derivatives were applied to reduce the influence of systematic disturbances. The performance of the methods was evaluated by comparison of the standard error of cross-validation (SECV), R(2), and the ratio performance deviation (RPD). Limits of detection (LOD) and limits of quantification (LOQ) of all methods were determined. For NIR-CI, a SECVcorr-spec and a SECVsingle-pixel corrected were calculated to assess the loss of accuracy by taking advantage of the spatial information. NIR-CI showed a SECVcorr-spec (SECVsingle-pixel corrected) of 2.82% (3.71%), 3.49% (4.65%), and 4.10% (5.06%) for form I, II, III. NIR had a SECV of 2.98%, 3.62%, and 2.75%, and Raman reached 3.25%, 3.08%, and 3.18%. The SECV of the ATR-IR models were 7.46%, 7.18%, and 12.08%. This study proves that NIR-CI, NIR, and Raman are well suited to quantify forms I-III of furosemide in ternary mixtures. Because of the pressure-dependent conversion of form II to form I, ATR-IR was found to be less appropriate for an accurate quantification of the mixtures. In this study, the capability of NIR-CI for the quantification of polymorphic ternary mixtures was compared with conventional spectroscopic techniques for the first time. For this purpose, a new way of spectra selection was chosen, and two kinds of SECVs were calculated to achieve a better comparability of NIR-CI to NIR, Raman, and ATR-IR. Copyright © 2013 Elsevier B.V. All rights reserved.

Fast determination of 3-ethenylpyridine as a marker of environmental tobacco smoke at trace level using direct atmospheric pressure chemical ionization tandem mass spectrometry

NASA Astrophysics Data System (ADS)

Jiang, Cheng-Yong; Sun, Shi-Hao; Zhang, Qi-Dong; Liu, Jun-Hui; Zhang, Jian-Xun; Zong, Yong-Li; Xie, Jian-Ping

2013-03-01

A method with atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS/MS) was developed and applied to direct analysis of Environmental Tobacco Smoke (ETS), using 3-ethenylpyridine (3-EP) as a vapour-phase marker. In this study, the ion source of APCI-MS/MS was modified and direct analysis of gas sample was achieved by the modified instrument. ETS samples were directly introduced, via an atmospheric pressure inlet, into the APCI source. Ionization was carried out in positive-ion APCI mode and 3-EP was identified by both full scan mode and daughter scan mode. Quantification of 3-EP was performed by multiple reaction monitoring (MRM) mode. The calibration curve was obtained in the range of 1-250 ng L-1 with a satisfactory regression coefficient of 0.999. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.5 ng L-1 and 1.6 ng L-1, respectively. The precision of the method, calculated as relative standard deviation (RSD), was characterized by repeatability (RSD 3.92%) and reproducibility (RSD 4.81%), respectively. In real-world ETS samples analysis, compared with the conventional GC-MS method, the direct APCI-MS/MS has shown better reliability and practicability in the determination of 3-EP at trace level. The developed method is simple, fast, sensitive and repeatable; furthermore, it could provide an alternative way for the determination of other volatile pollutants in ambient air at low levels.

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

PubMed

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

2014-07-01

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

Multiresidue Method for Quantification of Sulfonamides and Trimethoprim in Tilapia Fillet by Liquid Chromatography Coupled to Quadrupole Time-of-Flight Mass Spectrometry Using QuEChERS for Sample Preparation.

PubMed

Nunes, Kátia S D; Assalin, Márcia R; Vallim, José H; Jonsson, Claudio M; Queiroz, Sonia C N; Reyes, Felix G R

2018-01-01

A multiresidue method for detecting and quantifying sulfonamides (sulfapyridine, sulfamerazine, sulfathiazole, sulfamethazine, sulfadimethoxine, sulfamethoxazole, and sulfamethoxypyridazine) and trimethoprim in tilapia fillet ( Oreochromis niloticus ) using liquid chromatography coupled to mass spectrometry was developed and validated. The sample preparation was optimized using the QuEChERS approach. The chromatographic separation was performed using a C18 column and 0.1% formic acid in water and acetonitrile as the mobile phase in the isocratic elution mode. Method validation was performed based on the Commission Decision 2002/657/EC and Brazilian guideline. The validation parameters evaluated were linearity ( r  ≥ 0.99); limits of detection (LOD) and quantification (LOQ), 1 ng·g -1 and 5 ng·g -1 , respectively; intraday and interdays precision (CV lower than 19.4%). The decision limit (CC α 102.6-120.0 ng·g -1 and 70 ng·g -1 for sulfonamides and trimethoprim, respectively) and detection capability (CC β 111.7-140.1 ng·g -1 and 89.9 ng·g -1 for sulfonamides and trimethoprim, respectively) were determined. Analyses of tilapia fillet samples from fish exposed to sulfamethazine through feed (incurred samples) were conducted in order to evaluate the method. This new method was demonstrated to be fast, sensitive, and suitable for monitoring sulfonamides and trimethoprim in tilapia fillet in health surveillance programs, as well as to be used in pharmacokinetics and residue depletion studies.

[Determination of 11 anabolic hormones in fish tissue by multi-function impurity adsorption solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry].

PubMed

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

2012-06-01

A method was developed for the determination of 11 anabolic hormones (boldenone, androstenedione, nandrolone, methandrostenolone, methyltestosterone, testosterone, testosterone acetate, trenbolone, testosterone propionate, stanozolol, fluoxymesterone) in fish by multi-function impurity adsorption solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry. After the sample was extracted by methanol, the extract was cleaned-up quickly by C18 adsorbent, neutral alumina adsorbent and amino-functionalized nano-adsorbent. The separation was performed on a Shim-Pack XR-ODS II column (100 mm x 2.0 mm, 2.2 microm) using the mobile phases of 0.1% (v/v) formic acid in acetonitrile and 0.1% (v/v) formic acid solution in a gradient elution mode. The identification and quantification were achieved by using electrospray ionization in positive ion mode (ESI+) in multiple reaction monitoring (MRM) mode. The matrix-matched external standard calibration curves were used for quantitative determination. The results showed that the calibration curves were in good linearity for the eleven analytes with the correlation coefficients (r) more than 0.999. The limits of detection (LODs, S/N > 3) for the 11 anabolic hormones were from 0.03 microg/kg to 0.4 microg/kg and the limits of quantification (LOQs, S/N > 10) were from 0.1 microg/kg to 1.5 microg/kg. The average recoveries ranged from 80.9% to 98.1% with the relative standard deviations between 5.2% and 11.5%. The method is simple, rapid, sensitive, accurate and suitable for the quantitative determination and confirmation of the 11 anabolic hormones in fish.

Multiresidue Method for Quantification of Sulfonamides and Trimethoprim in Tilapia Fillet by Liquid Chromatography Coupled to Quadrupole Time-of-Flight Mass Spectrometry Using QuEChERS for Sample Preparation

PubMed Central

Nunes, Kátia S. D.; Assalin, Márcia R.; Vallim, José H.; Jonsson, Claudio M.; Queiroz, Sonia C. N.

2018-01-01

A multiresidue method for detecting and quantifying sulfonamides (sulfapyridine, sulfamerazine, sulfathiazole, sulfamethazine, sulfadimethoxine, sulfamethoxazole, and sulfamethoxypyridazine) and trimethoprim in tilapia fillet (Oreochromis niloticus) using liquid chromatography coupled to mass spectrometry was developed and validated. The sample preparation was optimized using the QuEChERS approach. The chromatographic separation was performed using a C18 column and 0.1% formic acid in water and acetonitrile as the mobile phase in the isocratic elution mode. Method validation was performed based on the Commission Decision 2002/657/EC and Brazilian guideline. The validation parameters evaluated were linearity (r ≥ 0.99); limits of detection (LOD) and quantification (LOQ), 1 ng·g−1 and 5 ng·g−1, respectively; intraday and interdays precision (CV lower than 19.4%). The decision limit (CCα 102.6–120.0 ng·g−1 and 70 ng·g−1 for sulfonamides and trimethoprim, respectively) and detection capability (CCβ 111.7–140.1 ng·g−1 and 89.9 ng·g−1 for sulfonamides and trimethoprim, respectively) were determined. Analyses of tilapia fillet samples from fish exposed to sulfamethazine through feed (incurred samples) were conducted in order to evaluate the method. This new method was demonstrated to be fast, sensitive, and suitable for monitoring sulfonamides and trimethoprim in tilapia fillet in health surveillance programs, as well as to be used in pharmacokinetics and residue depletion studies. PMID:29686929

Simultaneous Determination of Celecoxib, Erlotinib, and its Metabolite Desmethyl-Erlotinib (OSI-420) in Rat Plasma by Liquid chromatography/Tandem Mass Spectrometry with Positive/Negative Ion-Switching Electrospray Ionisation

PubMed Central

Thappali, Satheeshmanikandan R. S.; Varanasi, Kanthikiran; Veeraraghavan, Sridhar; Arla, Rambabu; Chennupati, Sandhya; Rajamanickam, Madheswaran; Vakkalanka, Swaroop; Khagga, Mukkanti

2012-01-01

A new method for the simultaneous determination of celecoxib, erlotinib, and its active metabolite desmethyl-erlotinib (OSI-420) in rat plasma, by liquid chromatography/tandem mass spectrometry with positive/negative ion-switching electrospray ionization mode, was developed and validated. Protein precipitation with methanol was selected as the method for preparing the samples. The analytes were separated on a reverse-phase C18 column (50mm×4.6mm i.d., 3μ) using methanol: 2 mM ammonium acetate buffer, and pH 4.0 as the mobile phase at a flow rate 0.8 mL/min. Sitagliptin and Efervirenz were used as the internal standards for quantification. The determination was carried out on a Theremo Finnigan Quantam ultra triple-quadrupole mass spectrometer, operated in selected reaction monitoring (SRM) mode using the following transitions monitored simultaneously: positive m/z 394.5→278.1 for erlotinib, m/z 380.3→278.1 for desmethyl erlotinib (OSI-420), and negative m/z −380.1→ −316.3 for celecoxib. The limits of quantification (LOQs) were 1.5 ng/mL for Celecoxib, erlotinib, and OSI-420. Within- and between-day accuracy and precision of the validated method were within the acceptable limits of < 15% at all concentrations. The quantitation method was successfully applied for the simultaneous estimation of celecoxib, erlotinib, and desmethyl erlotinib in a pharmacokinetic study in Wistar rats. PMID:23008811

Preconcentration of Trace Neonicotinoid Insecticide Residues Using Vortex-Assisted Dispersive Micro Solid-Phase Extraction with Montmorillonite as an Efficient Sorbent.

PubMed

Moyakao, Khwankaew; Santaladchaiyakit, Yanawath; Srijaranai, Supalax; Vichapong, Jitlada

2018-04-11

In this work, we investigated montmorillonite for adsorption of neonicotinoid insecticides in vortex-assisted dispersive micro-solid phase extraction (VA-d-μ-SPE). High-performance liquid chromatography with photodiode array detection was used for quantification and determination of neonicotinoid insecticide residues, including thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid. In this method, the solid sorbent was dispersed into the aqueous sample solution and vortex agitation was performed to accelerate the extraction process. Finally, the solution was filtered from the solid sorbent with a membrane filter. The parameters affecting the extraction efficiency of the proposed method were optimized, such as amount of sorbent, sample volume, salt addition, type and volume of extraction solvent, and vortex time. The adsorbing results show that montmorillonite could be reused at least 4 times and be used as an effective adsorbent for rapid extraction/preconcentration of neonicotinoid insecticide residues. Under optimum conditions, linear dynamic ranges were achieved between 0.5 and 1000 ng mL -1 with a correlation of determination ( R² ) greater than 0.99. Limit of detection (LOD) ranged from 0.005 to 0.065 ng mL -1 , while limit of quantification (LOQ) ranged from 0.008 to 0.263 ng mL -1 . The enrichment factor (EF) ranged from 8 to 176-fold. The results demonstrated that the proposed method not only provided a more simple and sensitive method, but also can be used as a powerful alternative method for the simultaneous determination of insecticide residues in natural surface water and fruit juice samples.

Association of placenta organotin concentrations with growth and ponderal index in 110 newborn boys from Finland during the first 18 months of life: a cohort study

PubMed Central

2014-01-01

Background Humans are exposed to tributyltin (TBT), previously used as an antifouling paint in ships, mainly through fish consumption. As TBT is a known obesogen, we studied the association of placenta TBT and other organotin compounds (OTCs) with ponderal index (PI) and growth during the first 18 months of life in boys. Methods In a prospective Finnish study, 110 placenta samples were collected from mothers of boys born in 1997–1999 with (n = 55) and without (n = 55) cryptorchidism. To account for the original study design, linear regression, weighted for sampling fractions of boys with (121/55) and without (5677/55) cryptorchidism from the total cohort, was used to study the association between placenta OTCs and children’s weight, length, growth rates and PI up to 18 months of age. Results Placenta TBT concentrations were above the limit of quantification (LOQ) in 99% of the samples. However, monobutyltin (MBT), dibutyltin (DBT) and triphenyltin (TPhT) concentrations were below LOQ in 90%, 35% and 57% of samples, respectively. Placenta TBT was positively associated (p = 0.024) with weight gain during the first three months of life, but no other significant associations were observed for weight or length gain. Also, no significant associations between placenta OTC concentrations and child length, weight or PI at any time point were found. Conclusions We observed a trend towards higher weight gain from birth to 3 months of age with increasing placenta TBT concentration. These results should be interpreted with caution because obesogenic effects in animal experiments were seen after in-utero TBT exposures to doses that were orders of magnitude higher. Also the number of study subjects included in this study was limited. PMID:24899383

Analytical method for the trace determination of esterified 3- and 2-monochloropropanediol and glycidyl fatty acid esters in various food matrices.

PubMed

Samaras, Vasilios G; Giri, Anupam; Zelinkova, Zuzana; Karasek, Lubomir; Buttinger, Gerhard; Wenzl, Thomas

2016-09-30

Fatty acid esters of 3-monochloro-1,2-propanediol (3-MCPDEs), of 2-monochloro-1,3-propanediol (2-MCPDEs) and of 2,3-epoxy-1-propanol or glycidol (GEs), which are considered to be deleterious to human health, may occur in a broad variety of food samples. A proper risk assessment of those substances requires the availability of robust occurrence data; in this respect concerns have been raised regarding the reliability of results obtained with the currently available methods to determine those substances in processed food. This article presents an indirect analytical procedure for the simultaneous determination of 3-MCPDEs, 2-MCPDEs and GEs in a wide variety of food products after extraction by pressurised liquid extraction (PLE) and determination by gas chromatography mass-spectrometry (GC-MS). For the differentiation of MCPDEs and GEs, the latter were first converted to monobromopropanediol esters (MBPDEs) in acid aqueous solution of sodium bromide. MCPDEs and MBPDEs were then hydrolysed under acidic conditions followed by derivatisation of the released free (non-esterified) form in ethyl acetate with phenyl boronic acid (PBA). Quantification of the analytes was carried out using the isotopic labelled analogues of both MCPDEs and GEs. Limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 7-17mgkg(-1) and 13-31mgkg(-1) respectively, while the working range of the method was between LOQ and 1850mgkg(-1) expressed on fat basis. The developed method was successfully applied for the analysis of the target compounds in more than 650 different food samples covering the following commodities: bread and rolls, fine bakery wares, smoked fish products, fried and roasted meat, potato based snacks and fried potato products, cereal-based snacks and margarines. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Determination of Bortezomib in API Samples Using HPLC: Assessment of Enantiomeric and Diastereomeric Impurities.

PubMed

Kamalzadeh, Zahra; Babanezhad, Esmaeil; Ghaffari, Solmaz; Mohseni Ezhiyeh, Alireza; Mohammadnejad, Mahdieh; Naghibfar, Mehdi; Bararjanian, Morteza; Attar, Hossein

2017-08-01

A new, normal phase high performance liquid chromatography (NP-HPLC) method was developed for separation of Bortezomib (BZB) enantiomers and quantitative determination of (1S,2R)-enantiomer of BZB in active pharmaceutical ingredient (API) samples. The developed method was validated based on International Conference on Harmonisation (ICH) guidelines and it was proved to be accurate, precise and robust. The obtained resolution (RS) between the enantiomers was more than 2. The calibration curve for (1S,2R)-enantiomer was found to be linear in the concentration range of 0.24-5.36 mg/L with regression coefficient (R2) of 0.9998. Additionally, the limit of detection (LOD) and limit of quantification (LOQ) were 0.052 and 0.16 mg/L, respectively. Also, in this study, a precise, sensitive and robust gradient reversed-phase HPLC (RP-HPLC) method was developed and validated for determination of BZB in API samples. The detector response was linear over the concentration range of 0.26-1110.5 mg/L. The values of R2, LOD and LOQ were 0.9999, 0.084 and 0.25 mg/L, respectively. For both NP-HPLC and RP-HPLC methods, all of the RSD (%) values obtained in the precision study were <1.0%. System suitability parameters in terms of tailing factor (TF), number of theoretical plates (N) and RS were TF < 2.0, N > 2,000 and RS > 2.0. The performance of two common integration methods of valley to valley and drop perpendicular for drawing the baseline between two adjacent peaks were investigated for the determination of diastereomeric impurity (Imp-D) in the BZB-API samples. The results showed that the valley to valley method outperform the drop perpendicular method for calculation of Imp-D peak areas. Therefore, valley to valley method was chosen for peak integration. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Urinary levels of bisphenol analogues in residents living near a manufacturing plant in south China.

PubMed

Yang, Yunjia; Guan, Jian; Yin, Jie; Shao, Bing; Li, Hong

2014-10-01

The use of bisphenol A (BPA) has been restricted in many countries because of its potential health effects. As a result of these restrictions, a group of bisphenol analogues that are structurally similar to BPA have been developed as the alternatives for industrial applications. However, latest researches indicated that these chemicals have similar endocrine-disrupting effects as BPA in humans. Moreover, only a limited number of studies have attempted to monitor the exposure level in humans of other bisphenol analogues. In the present study, the concentrations of seven bisphenols, including bisphenol S (BPS), bisphenol F (BPF), bisphenol B (BPB), BPA, bisphenol AF (BPAF), tetrachlorobisphenol A (TCBPA) and tetrabromobisphenol A (TBBPA), in human urine samples were measured by liquid chromatography coupled to mass spectrometry (LC-MS/MS) following the enzymatic hydrolysis of glucuronidase/arylsulfatase and liquid-liquid extraction (LLE). Under the optimised conditions, high recoveries (81.6-116.8%) were obtained for all the analytes, and the relative standard deviations (RSD, %) were less than 16.4% (n=6). The isotopic internal standard calibration curves for each of the target compounds exhibited excellent linearity (r(2)>0.99) and the limit of quantification (LOQ) for the analytes in urine ranged from 0.024 to 0.310 ng mL(-1). The method was applied to investigate the urinary levels of these seven bisphenols in a cohort of residents living near a BPAF manufacturing plant in south China. BPS, BPF, BPA and BPAF were detected in urine samples at concentrations ranging from

Degradation studies of quizalofop-p and related compounds in soils using liquid chromatography coupled to low and high resolution mass analyzers.

PubMed

López-Ruiz, Rosalía; Romero-González, Roberto; Martínez Vidal, José Luis; Fernández-Pérez, Manuel; Garrido Frenich, Antonia

2017-12-31

A comprehensive degradation study of quizalofop-p, quizalofop-p-ethyl, quizalofop-p-tefuryl and propaquizafop in soil samples have been firstly performed using ultra high performance liquid chromatography coupled to Orbitrap mass spectrometry (UHPLC-Orbitrap-MS). Thus, metabolites or degradation products, such as CHHQ (dihydroxychloroquinoxalin), CHQ (6-chloroquinoxalin-2-ol), PPA ((R)-2-(4-hydroxyphenoxy)propionic acid) and 2,3-dihydroxyquinoxaline were also monitored. An extraction procedure based on QuEChERS procedure was used. Acidified water (0.1M hydrochloric acid) and acidified acetonitrile (1% acetic acid, (v/v)) were used as extraction solvents, and magnesium sulfate and sodium chloride were used as salts. Dispersive solid phase extraction with C 18 as sorbent, was needed as a clean-up step. Several commercial products (Panarex®, Master-D® and Dixon®) were used to evaluate the degradation of the target compounds into their metabolites. The concentration of the main active substances (quizalofop-p-tefuryl, quizalofop-p-ethyl and propaquizafop) decreased during the degradation studies, whereas the concentration of quizalofop-p increased. Dissipation rates of half-live of quizalofop-p were also evaluated, and it was observed that this compound is easily degraded, obtaining values lower than 1day. Taking into account that quizalofop-p is the R enantiomer of quizalofop, a chiral separation was performed by liquid chromatography coupled to tandem mass spectrometry, concluding that in samples containing quizalofop-p-tefuryl, there was a 15% contribution from the S enantiomer and a 85% contribution from the R enantiomer. Metabolites such as PPA, CHHQ and CHQ were detected in soil samples after 15days of application commercial product at concentrations between the limits of detection (LOD) and the limits of quantification (LOQ). CHQ and CHHQ were detected at concentrations higher than the LOQ in samples after 50 and 80days of application, with their concentration increasing during this time up to 500%. Copyright © 2017 Elsevier B.V. All rights reserved.

Establishment and application of event-specific polymerase chain reaction methods for two genetically modified soybean events, A2704-12 and A5547-127.

PubMed

Li, Xiang; Pan, Liangwen; Li, Junyi; Zhang, Qigang; Zhang, Shuya; Lv, Rong; Yang, Litao

2011-12-28

For implementation of the issued regulations and labeling policies for genetically modified organism (GMO) supervision, the polymerase chain reaction (PCR) method has been widely used due to its high specificity and sensitivity. In particular, use of the event-specific PCR method based on the flanking sequence of transgenes has become the primary trend. In this study, both qualitative and quantitative PCR methods were established on the basis of the 5' flanking sequence of transgenic soybean A2704-12 and the 3' flanking sequence of transgenic soybean A5547-127, respectively. In qualitative PCR assays, the limits of detection (LODs) were 10 copies of haploid soybean genomic DNA for both A2704-12 and A5547-127. In quantitative real-time PCR assays, the LODs were 5 copies of haploid soybean genomic DNA for both A2704-12 and A5547-127, and the limits of quantification (LOQs) were 10 copies for both. Low bias and acceptable SD and RSD values were also achieved in quantification of four blind samples using the developed real-time PCR assays. In addition, the developed PCR assays for the two transgenic soybean events were used for routine analysis of soybean samples imported to Shanghai in a 6 month period from October 2010 to March 2011. A total of 27 lots of soybean from the United States and Argentina were analyzed: 8 lots from the Unites States were found to have the GM soybean A2704-12 event, and the GM contents were <1.5% in all eight analyzed lots. On the contrary, no GM soybean A5547-127 content was found in any of the eight lots. These results demonstrated that the established event-specific qualitative and quantitative PCR methods could be used effectively in routine identification and quantification of GM soybeans A2704-12 and A5547-127 and their derived products.

[To consider negative viral loads below the limit of quantification can lead to errors in the diagnosis and treatment of hepatitis C virus infection].

PubMed

Acero Fernández, Doroteo; Ferri Iglesias, María José; López Nuñez, Carme; Louvrie Freire, René; Aldeguer Manté, Xavier

2013-01-01

For years many clinical laboratories have routinely classified undetectable and unquantifiable levels of hepatitis C virus RNA (HCV-RNA) determined by RT-PCR as below limit of quantification (BLOQ). This practice might result in erroneous clinical decisions. To assess the frequency and clinical relevance of assuming that samples that are BLOQ are negative. We performed a retrospective analysis of RNA determinations performed between 2009 and 2011 (Cobas/Taqman, lower LOQ: 15 IU/ml). We distinguished between samples classified as «undetectable» and those classified as «<1.50E+01IU/mL» (BLOQ). We analyzed 2.432 HCV-RNA measurements in 1.371 patients. RNA was BLOQ in 26 samples (1.07%) from 23 patients (1.68%). BLOQ results were highly prevalent among patients receiving Peg-Riba: 23 of 216 samples (10.6%) from 20 of 88 patients receiving treatment (22.7%). The clinical impact of BLOQ RNA samples was as follows: a) 2 patients initially considered to have negative results subsequently showed quantifiable RNA; b) 8 of 9 patients (88.9%) with BLOQ RNA at week 4 of treatment later showed sustained viral response; c) 3 patients with BLOQ RNA at weeks 12 and 48 of treatment relapsed; d) 4 patients with BLOQ RNA at week 24 and/or later had partial or breakthrough treatment responses, and e) in 5 patients the impact were null or could not be ascertained. This study suggests that BLOQ HCV-RNA indicates viremia and that equating a BLOQ result with a negative result can lead to treatment errors. BLOQ results are highly prevalent in on-treatment patients. The results of HCV-RNA quantification should be classified clearly, distinguishing between undetectable levels and levels that are BLOQ. Copyright © 2013 Elsevier España, S.L. and AEEH y AEG. All rights reserved.

Screening method for the determination of tetracyclines and fluoroquinolones in animal drinking water by liquid chromatography with diode array detector.

PubMed

Patyra, E; Kowalczyk, E; Grelik, A; Przeniosło-Siwczyńska, M; Kwiatek, K

2015-01-01

A liquid chromatography - diode array detector (HPLC-DAD) procedure has been developed for the determination of oxytetracycline (OTC), tetracycline (TC), chlorotetracycline (CTC), doxycycline (DC), enrofloxacin (ENR), ciprofloxacin (CIP), sarafloxacin (SAR) and flumequine (FLU) residues in animal drinking water. This method was applied to animal drinking water. Solid-phase extraction (SPE) clean-up on an Oasis HLB cartridge allowed an extract suitable for liquid chromatographic analysis to be obtained. Chromatographic separation was carried out on a C18 analytical column, using gradient elution with 0.1% trifluoroacetic acid - acetonitrile - methanol at 30°C. The flow-rate was 0.7 mL/min and the eluate was analysed at 330 nm. The whole procedure was evaluated according to the requirements of the Commission Decision 2002/657/EC, determining specificity, decision limit (CCα), detection capacity (CCβ), limit of detection (LOD), limit of quantification (LOQ), precision and accuracy during validation of the method. The recoveries of TCs and FQs from spiked samples at the levels of 10, 100 and 1000 μg/L were higher than 82%. The developed method based on HPLC-DAD has been applied for the determination of four tetracyclines and four fluoroquinolones in animal drinking water samples.

Risk assessment and monitoring of dinotefuran and its metabolites for Chinese consumption of apples.

PubMed

Yu, Weiwei; Huang, Min; Chen, Jiaojiao; Wu, Sizhuo; Zheng, Kunming; Zeng, Song; Zhang, Kankan; Hu, Deyu

2017-09-26

Residues of dinotefuran and its metabolites, 1-methyl-3-(tetrahydro-3-furylmethyl)urea (UF) and 1-methyl-3-(tetrahydro-3-furylmethyl)guanidine (DN), in apple were investigated using a "QuEChERS" (quick, easy, cheap, effective, rugged, safe) pretreatment and liquid chromatography-tandem mass spectrometry. Limits of detection (LODs) and quantification (LOQs) of dinotefuran, UF, and DN in apples were 0.011-0.960 and 0.037-3.200 μg/kg, respectively. The average recoveries of dinotefuran, UF, and DN in apple ranged from 70.0 to 83.6% with relative standard deviations less than 13%. A formulation of 20% water-dispersible dinotefuran granules was sprayed at 1-1.5-fold the recommended dose 3-4 times on apple trees. Total terminal residues of dinotefuran in apple were less than 2 mg/kg, which is the maximum residue limit (MRL) set by Japan. When following the recommended application guidelines, dinotefuran is unlikely to present significant health concerns to the Chinese population because the risk quotient (RQ) is less than 100%. This work could provide guidance for the safe use of dinotefuran and serve as a reference for the establishment of a maximum residue limit of dinotefuran in apple in China.

Total Arsenic, Cadmium, and Lead Determination in Brazilian Rice Samples Using ICP-MS

PubMed Central

Buzzo, Márcia Liane; de Arauz, Luciana Juncioni; Carvalho, Maria de Fátima Henriques; Arakaki, Edna Emy Kumagai; Matsuzaki, Richard; Tiglea, Paulo

2016-01-01

This study is aimed at investigating a suitable method for rice sample preparation as well as validating and applying the method for monitoring the concentration of total arsenic, cadmium, and lead in rice by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Various rice sample preparation procedures were evaluated. The analytical method was validated by measuring several parameters including limit of detection (LOD), limit of quantification (LOQ), linearity, relative bias, and repeatability. Regarding the sample preparation, recoveries of spiked samples were within the acceptable range from 89.3 to 98.2% for muffle furnace, 94.2 to 103.3% for heating block, 81.0 to 115.0% for hot plate, and 92.8 to 108.2% for microwave. Validation parameters showed that the method fits for its purpose, being the total arsenic, cadmium, and lead within the Brazilian Legislation limits. The method was applied for analyzing 37 rice samples (including polished, brown, and parboiled), consumed by the Brazilian population. The total arsenic, cadmium, and lead contents were lower than the established legislative values, except for total arsenic in one brown rice sample. This study indicated the need to establish monitoring programs for emphasizing the study on this type of cereal, aiming at promoting the Public Health. PMID:27766178

An innovative ultrasound assisted extraction micro-scale cell combined with gas chromatography/mass spectrometry in negative chemical ionization to determine persistent organic pollutants in air particulate matter.

PubMed

Beristain-Montiel, E; Villalobos-Pietrini, R; Arias-Loaiza, G E; Gómez-Arroyo, S L; Amador-Muñoz, O

2016-12-16

New clean technologies are needed to determine concentration of organic pollutants without generating more pollution. A method to extract Persistent Organic Pollutants (POPs) from airborne particulate matter was developed using a novel technology recently patented called ultrasound assisted extraction micro-scale cell (UAE-MSC). This technology extracts, filters, collects the sample, and evaporates the solvent, on-line. No sample transfer is needed. The cell minimizes sample manipulation, solvent consumption, waste generation, time, and energy; fulfilling most of the analytical green chemistry protocol. The methodology was optimized applying a centred 2 3 factorial experimental design. Optimum conditions were used to validate and determine concentration of 16 organochlorine pesticides (OCls) and 6 polybrominated diphenyl ethers (PBDEs). The best conditions achieved were 2 extractions with 5mL (each) of dichloromethane over 5min (each) at 60°C and 80% ultrasound potency. POPs were determined by gas chromatography/mass spectrometry in negative chemical ionization (GC/MS-NCI). Analytical method validation was carried out on airborne particles spiked with POPs at seven concentration levels between 0.5 and 26.9pgm -3 . This procedure was done by triplicate (N=21). Recovery, ranged between 65.5±2.3% and 107.5±3.0% for OCls and between 79.1±6.5% and 105.2±3.8% for PBDEs. Linearity (r 2 ) was ≥0.94 for all compounds. Method detection limits, ranged from 0.5 to 2.7pgm -3 , while limits of quantification (LOQ), ranged from 1.7 to 9.0pgm -3 . A Bias from -18.6% to 9% for PBDEs was observed in the Standard Reference Material (SRM) 2787. SRM 2787 did not contain OCls. OCls recoveries were equivalent by UAE-MSC and Soxhlet methods UAE-MSC optimized extraction conditions reduced 30 times less solvent and decreased the extraction time from several hours to ten minutes, respect to Soxhlet. UAE-MSC was applied to 15 samples of particles less than 2.5μm (PM 2.5 ) from three seasons (warm dry, rainy, and cold dry) collected in five sites around Mexico City. OCls (4,4'-DDE and endrin aldehyde) concentrations ranged from

Multianalyte, high-throughput liquid chromatography tandem mass spectrometry method for the sensitive determination of fungicides and insecticides in wine.

PubMed

Castro, Gabriela; Pérez-Mayán, Leticia; Rodríguez-Cabo, Tamara; Rodríguez, Isaac; Ramil, Maria; Cela, Rafael

2018-01-01

Evidence of pesticide transfer from grapes to wine, added to differences in the national regulations regarding the number and the maximum concentration of these species in wine, demands analytical procedures suitable for their routine control in this foodstuff. In this research, solid-phase extraction (SPE) and ultra-performance liquid chromatography (UPLC), with tandem mass spectrometry (MS/MS) detection, are combined to obtain a sensitive and rapid procedure to determine 50 pesticides in red and white wines. Efficiency and selectivity of sample preparation are correlated with the type of sorbent, the elution solvent, and the physicochemical properties of pesticides. SPE of 2-mL wine samples followed by direct injection of the extract in the UPLC-MS/MS system provides quantification limits (LOQs) below 1 ng mL -1 for 48 out of 50 compounds, linear responses up to 200 ng mL -1 , and acceptable accuracy, employing quantification against solvent-based standards, for 45 species. A total analysis time of 10 min, including compounds separation and re-equilibration of the UPLC column, was achieved. The developed methodology was applied to 25 wines (20 conventional and 5 ecological), produced in 7 different countries. Out of 27 pesticides quantified in these wines, 12 displayed occurrence frequencies above 24%; moreover, all wines, except one of the ecological ones, contained residues from at least one pesticide.

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

NASA Astrophysics Data System (ADS)

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

2017-02-01

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

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

PubMed Central

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

2017-01-01

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

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

PubMed

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

2017-02-22

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

A Simple and Specific Stability- Indicating RP-HPLC Method for Routine Assay of Adefovir Dipivoxil in Bulk and Tablet Dosage Form.

PubMed

Darsazan, Bahar; Shafaati, Alireza; Mortazavi, Seyed Alireza; Zarghi, Afshin

2017-01-01

A simple and reliable stability-indicating RP-HPLC method was developed and validated for analysis of adefovir dipivoxil (ADV).The chromatographic separation was performed on a C 18 column using a mixture of acetonitrile-citrate buffer (10 mM at pH 5.2) 36:64 (%v/v) as mobile phase, at a flow rate of 1.5 mL/min. Detection was carried out at 260 nm and a sharp peak was obtained for ADV at a retention time of 5.8 ± 0.01 min. No interferences were observed from its stress degradation products. The method was validated according to the international guidelines. Linear regression analysis of data for the calibration plot showed a linear relationship between peak area and concentration over the range of 0.5-16 μg/mL; the regression coefficient was 0.9999and the linear regression equation was y = 24844x-2941.3. The detection (LOD) and quantification (LOQ) limits were 0.12 and 0.35 μg/mL, respectively. The results proved the method was fast (analysis time less than 7 min), precise, reproducible, and accurate for analysis of ADV over a wide range of concentration. The proposed specific method was used for routine quantification of ADV in pharmaceutical bulk and a tablet dosage form.

Employing natural reagents from turmeric and lime for acetic acid determination in vinegar sample.

PubMed

Supharoek, Sam-Ang; Ponhong, Kraingkrai; Siriangkhawut, Watsaka; Grudpan, Kate

2018-04-01

A simple, rapid and environmentally friendly sequential injection analysis system employing natural extract reagents was developed for the determination of acetic acid following an acid-base reaction in the presence of an indicator. Powdered lime and turmeric were utilized as the natural base and indicator, respectively. Mixing lime and turmeric produced an orange to reddish-brown color solution which absorbed the maximum wavelength at 455 nm, with absorbance decreasing with increasing acetic acid concentration. Influential parameters including lime and turmeric concentrations, reagent and sample aspirated volumes, mixing coil length and dispensing flow rate were investigated and optimized. A standard calibration graph was plotted for 0-5.0 mmol/L acetic acid with r 2  = 0.9925. Relative standard deviations (RSD) at 2.0 and 4.0 mmol/L acetic acid were less than 3% (n = 7), with limit of detection (LOD) and limit of quantification (LOQ) at 0.12 and 0.24 mmol/L, respectively. The method was successfully applied to assay acetic acid concentration in cooking vinegar samples. Results achieved were not significantly different from those obtained following a batchwise standard AOAC titration method. Copyright © 2017. Published by Elsevier B.V.

Improved high-performance liquid chromatography (HPLC) method for qualitative and quantitative analysis of allantoin in Zea mays.

PubMed

Haghi, Ghasem; Arshi, Rohollah; Safaei, Alireza

2008-02-27

A high-performance liquid chromatography (HPLC) method for the qualitative and quantitative analysis of allantoin in silk and seed of Zea mays has been developed. Allantoin separation in crude extract was achieved using a C 18 column and phosphate buffer solution (pH 3.0) as a mobile phase at ambient temperature at a flow rate of 1.0 mL/min and detected at 210 nm. The results showed that the amount of allantoin in samples was between 14 and 271 mg/100 g of dry plant material. A comprehensive validation of the method including sensitivity, linearity, repeatability, and recovery was conducted. The calibration curve was linear over the range of 0.2-200 microg/mL with a correlation coefficient of r2>0.999. Limit of detection (LOD, S/N=3) and limit of quantification (LOQ) values of the allantoin were 0.05 and 0.2 microg/mL (1.0 and 4.0 ng) respectively. The relative standard deviation (RSD) value of the repeatability was reported within 1.2%. The average recovery of allantoin added to samples was 100.6% with RSD of 1.5%.

Separation and determination of impurities in paracetamol, codeine and pitophenone in the presence of fenpiverinium in combined suppository dosage form.

PubMed

Vojta, Jiří; Hanzlík, Pavel; Jedlička, Aleš; Coufal, Pavel

2015-01-01

A new HPLC method for separation and determination of impurities in paracetamol, codeine phosphate hemihydrate and pitophenone hydrochloride in the presence of fenpiverinium bromide in combined suppository dosage form was developed and validated. The separation of paracetamol and its impurities 4-aminophenol, 4-nitrophenol, 4-chloracetanilid; codeine and its impurities methylcodeine, morphine, codeine dimer and 10-hydroxycodeine; pitophenone and its impurities 2-[4-[2-(1-piperidinyl)ethoxy]benzoyl] benzoic acid, 2-[4-[2-(1-piperidinyl)ethoxy]benzoyl]benzoic acid 2-(1-piperidinyl)-ethyl ester, methyl ester of 2-(4-hydroxybenzoyl) benzoic acid and fenpiverinium was achieved by using ion-pair reversed phase liquid chromatography with UV detection. Validation parameters such as the precision, accuracy, linearity, limit of detection (LOD), limit of quantification (LOQ) and robustness were verified for all the mentioned impurities of codeine phosphate hemihydrate and 4-aminophenol and 2-[4-[2-(1-piperidinyl)ethoxy]benzoyl] benzoic acid as the main degradation products of paracetamol and pitophenone hydrochloride, respectively. The described method was found to be useful for analysis of the stability samples and therefore suitable for routine purity testing of the drug product. Copyright © 2014 Elsevier B.V. All rights reserved.

Validated spectrofluorimetric method for the determination of clonazepam in pharmaceutical preparations.

PubMed

Ibrahim, Fawzia; El-Enany, Nahed; Shalan, Shereen; Elsharawy, Rasha

2016-05-01

A simple, highly sensitive and validated spectrofluorimetric method was applied in the determination of clonazepam (CLZ). The method is based on reduction of the nitro group of clonazepam with zinc/CaCl2, and the product is then reacted with 2-cyanoacetamide (2-CNA) in the presence of ammonia (25%) yielding a highly fluorescent product. The produced fluorophore exhibits strong fluorescence intensity at ʎ(em) = 383 nm after excitation at ʎ(ex) = 333 nm. The method was rectilinear over a concentration range of 0.1-0.5 ng/mL with a limit of detection (LOD) of 0.0057 ng/mL and a limit of quantification (LOQ) of 0.017 ng/mL. The method was fully validated and successfully applied to the determination of CLZ in its tablets with a mean percentage recovery of 100.10 ± 0.75%. Method validation according to ICH Guidelines was evaluated. Statistical analysis of the results obtained using the proposed method was successfully compared with those obtained using a reference method, and there was no significance difference between the two methods in terms of accuracy and precision. Copyright © 2015 John Wiley & Sons, Ltd.

Residues and dissipation of kresoxim methyl in apple under field condition.

PubMed

Malhat, Farag; Kamel, Essam; Saber, Ayman; Hassan, Ehab; Youssef, Ahmed; Almaz, Monir; Hassan, Ayman; Fayz, Abd El-Salam

2013-09-01

The dissipation and residual levels of kresoxim methyl in apple under field condition were determined by using HPLC-DAD with QuEChERS method. At fortification levels of 0.05, 0.1, 0.5 and 1.0 mg kg(-1) in apple, it was shown that recoveries were ranged from 91.1% to 96.9% with coefficient variation of the method (CV%) for repeatability ranged from 1.27% to 4.77%. The limit of quantification (LOQ) of the method was 0.05 mg kg(-1). The dissipation rates of kresoxim methyl were described by using first-order kinetics and its half-life, as they are ranged from 4.58 to 4.77 days in apple. The terminal residues of kresoxim methyl were below the FAO/WHO maximum residue limit (MRL, 0.2 mg kg(-1)) in apple when measured 14 days after the final application, which suggested that the use of this fungicide was safe for humans. This study would help in providing the basic information for developing regulation to guard a safe use of kresoxim methyl in apple orchard and to prevent health problem from consumers. Copyright © 2013 Elsevier Ltd. All rights reserved.

Long-Term Occurrence of Deoxynivalenol in Feed and Feed Raw Materials with a Special Focus on South Korea.

PubMed

Park, Juhee; Chang, Hansub; Kim, Dongho; Chung, Soohyun; Lee, Chan

2018-03-16

The Fusarium fungi produce toxic substances called mycotoxins, which can cause disease and harmful effects in grains, livestock, and humans. Deoxynivalenol (DON), also known as vomitoxin, is one of the Fusarium mycotoxins that is known to cause vomiting in livestock. This study shows the occurrence of deoxynivalenol in feedstuffs (compound feed and feed ingredients) between 2009 and 2016 in South Korea. A total of 653 domestic samples were collected at five time points, including 494 compound feed samples and 159 feed ingredient samples. DON contamination levels were analyzed using high-performance liquid chromatography (HPLC) with pretreatment using an immunoaffinity column (IAC). The limit of detection (LOD) and the limit of quantification (LOQ) were estimated at 1-10 µg/kg and 3-35 µg/kg, respectively. Two compound feeds (two gestating sow feed samples) out of 160 pig feed samples exceeded the European Commission (EC) guidance value, while no feed ingredient samples exceeded the EC or South Korean guidance values. There were statistically significant differences in the mean contamination levels of compound feed and feed ingredients that indicated a decreasing trend over time.

Long-Term Occurrence of Deoxynivalenol in Feed and Feed Raw Materials with a Special Focus on South Korea

PubMed Central

Park, Juhee; Chang, Hansub; Kim, Dongho; Chung, Soohyun

2018-01-01

The Fusarium fungi produce toxic substances called mycotoxins, which can cause disease and harmful effects in grains, livestock, and humans. Deoxynivalenol (DON), also known as vomitoxin, is one of the Fusarium mycotoxins that is known to cause vomiting in livestock. This study shows the occurrence of deoxynivalenol in feedstuffs (compound feed and feed ingredients) between 2009 and 2016 in South Korea. A total of 653 domestic samples were collected at five time points, including 494 compound feed samples and 159 feed ingredient samples. DON contamination levels were analyzed using high-performance liquid chromatography (HPLC) with pretreatment using an immunoaffinity column (IAC). The limit of detection (LOD) and the limit of quantification (LOQ) were estimated at 1–10 µg/kg and 3–35 µg/kg, respectively. Two compound feeds (two gestating sow feed samples) out of 160 pig feed samples exceeded the European Commission (EC) guidance value, while no feed ingredient samples exceeded the EC or South Korean guidance values. There were statistically significant differences in the mean contamination levels of compound feed and feed ingredients that indicated a decreasing trend over time. PMID:29547546

Development of a candidate reference measurement procedure for the analysis of cortisol in human serum samples by isotope dilution-gas chromatography-mass spectrometry.

PubMed

Kawaguchi, Migaku; Takatsu, Akiko

2009-08-01

A candidate reference measurement procedure involving isotope dilution coupled with gas chromatography-mass spectrometry (GC-MS) has been developed and critically evaluated. An isotopically labeled internal standard, cortisol-d(2), was added to a serum sample. After equilibration, solid-phase extractions (SPE) for sample preparation and derivatization with heptafluorobutyric anhydride (HFBA) were performed for GC-MS analysis. The limit of detection (LOD) and the limit of quantification (LOQ) were 5 and 20 ng g(-1), respectively. The recovery of the added cortisol ranged from 99.8 to 101.0%. Excellent precision was obtained with a within-day variation (RSD) of 0.7% for GC-MS analysis. The accuracy of the measurement was evaluated by comparing of results of this reference measurement procedure on lyophilized human serum reference materials for cortisol (European Reference Materials (ERM)-DA 192) as Certified Reference Materials (CRMs). The results of this method for total cortisol agreed with the certified values within some uncertainty. This method, which demonstrates simply, easy, good accuracy, high precision, and is free from interferences from structural analogues, qualifies as a reference measurement procedure.

Qualitative and Quantitative Analysis of the Major Constituents in Chinese Medical Preparation Lianhua-Qingwen Capsule by UPLC-DAD-QTOF-MS

PubMed Central

Jia, Weina; Wang, Chunhua; Wang, Yuefei; Pan, Guixiang; Jiang, Miaomiao; Li, Zheng; Zhu, Yan

2015-01-01

Lianhua-Qingwen capsule (LQC) is a commonly used Chinese medical preparation to treat viral influenza and especially played a very important role in the fight against severe acute respiratory syndrome (SARS) in 2002-2003 in China. In this paper, a rapid ultraperformance liquid chromatography coupled with diode-array detector and quadrupole time-of-flight mass spectrometry (UPLC-DAD-QTOF-MS) method was established for qualitative and quantitative analysis of the major constituents of LQC. A total of 61 compounds including flavonoids, phenylpropanoids, anthraquinones, triterpenoids, iridoids, and other types of compounds were unambiguously or tentatively identified by comparing the retention times and accurate mass measurement with reference compounds or literature data. Among them, twelve representative compounds were further quantified as chemical markers in quantitative analysis, including salidroside, chlorogenic acid, forsythoside E, cryptochlorogenic acid, amygdalin, sweroside, hyperin, rutin, forsythoside A, phillyrin, rhein, and glycyrrhizic acid. The UPLC-DAD method was evaluated with linearity, limit of detection (LOD), limit of quantification (LOQ), precision, stability, repeatability, and recovery tests. The results showed that the developed quantitative method was linear, sensitive, and precise for the quality control of LQC. PMID:25654135

Molecularly imprinted solid-phase extraction coupled to liquid chromatography for determination of Sudan dyes in preserved beancurds.

PubMed

Yan, Hongyuan; Qiao, Jindong; Pei, Yuning; Long, Tao; Ding, Wen; Xie, Kun

2012-05-01

New molecularly imprinted microspheres synthesized by suspension polymerisation using phenylamine and naphthol as mimic template were successfully applied as selective sorbents for the solid-phase extraction used for the simultaneous determination of four Sudan dyes from preserved beancurd products. The obtained imprinted microspheres showed good recognition and selectivity to the four Sudan dyes in aqueous solution and the affinity could be easily controlled by adjusting the property of the solution. Under the selected experimental condition, the recoveries of the Sudan dyes in preserved beancurds at three spiked levels were ranged between 90.2-104.5% with the relative standard deviation of less than 6.8%. The limit of detection (LOD) and limit of quantification (LOQ) based on a signal-to-noise of 3 and 10 were in the range of 0.005-0.009μgg(-1) and 0.015-0.030μgg(-1), respectively. Comparing with alumina and C18-based extraction, the selectivity and repeatability of molecularly imprinted solid-phase extraction (MISPE) were obviously improved. This method could be potentially applied for the determination of Sudan dyes in complicated food samples. Copyright © 2011 Elsevier Ltd. All rights reserved.

Multiple biomarkers biosensor with just-in-time functionalization: Application to prostate cancer detection.

PubMed

Parra-Cabrera, C; Samitier, J; Homs-Corbera, A

2016-03-15

We present a novel lab-on-a-chip (LOC) device for the simultaneous detection of multiple biomarkers using simple voltage measurements. The biosensor functionalization is performed in-situ, immediately before its use, facilitating reagents storage and massive devices fabrication. Sensitivity, limit of detection (LOD) and limit of quantification (LOQ) are tunable depending on the in-chip flown sample volumes. As a proof-of-concept, the system has been tested and adjusted to quantify two proteins found in blood that are susceptible to be used combined, as a screening tool, to diagnose prostate cancer (PCa): prostate-specific antigen (PSA) and spondin-2 (SPON2). This combination of biomarkers has been reported to be more specific for PCa diagnostics than the currently accepted but rather controversial PSA indicator. The range of detection for PSA and SPON2 could be adjusted to the clinically relevant range of 1 to 10 ng/ml. The system was tested for specificity to the evaluated biomarkers. This multiplex system can be modified and adapted to detect a larger quantity of biomarkers, or different ones, of relevance to other specific diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

Development and validation of a HPTLC method for simultaneous estimation of lornoxicam and thiocolchicoside in combined dosage form

PubMed Central

Sahoo, Madhusmita; Syal, Pratima; Hable, Asawaree A.; Raut, Rahul P.; Choudhari, Vishnu P.; Kuchekar, Bhanudas S.

2011-01-01

Aim: To develop a simple, precise, rapid and accurate HPTLC method for the simultaneous estimation of Lornoxicam (LOR) and Thiocolchicoside (THIO) in bulk and pharmaceutical dosage forms. Materials and Methods: The separation of the active compounds from pharmaceutical dosage form was carried out using methanol:chloroform:water (9.6:0.2:0.2 v/v/v) as the mobile phase and no immiscibility issues were found. The densitometric scanning was carried out at 377 nm. The method was validated for linearity, accuracy, precision, LOD (Limit of Detection), LOQ (Limit of Quantification), robustness and specificity. Results: The Rf values (±SD) were found to be 0.84 ± 0.05 for LOR and 0.58 ± 0.05 for THIO. Linearity was obtained in the range of 60–360 ng/band for LOR and 30–180 ng/band for THIO with correlation coefficients r2 = 0.998 and 0.999, respectively. The percentage recovery for both the analytes was in the range of 98.7–101.2 %. Conclusion: The proposed method was optimized and validated as per the ICH guidelines. PMID:23781452

Fast analysis of 4-tertoctylphenol, pentachlorophenol and 4-nonylphenol in river sediments by QuEChERS extraction procedure combined with GC-QqQ-MS/MS.

PubMed

Czech, T; Bonilla, N Barco; Gambus, F; González, R Romero; Marín-Sáez, J; Vidal, J L Martínez; Frenich, A Garrido

2016-07-01

A quick, easy, cheap, effective, rugged and safe (QuEChERS)-based extraction method has been optimized for the determination of pentachlorophenol, 4-tertoctylphenol and 4-nonylphenol in river sediments. The extraction method was followed by gas chromatography-triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS) analysis, which ensures the reliable identification of the target compounds. The proposed method has been validated allowing the successful determination of the selected compounds, with recoveries ranging from 72 to 96%, when three concentration levels were evaluated (10, 50 and 100μgkg(-1)) and inter-day and intra-day precision, expressed as relative standard deviation (RSD), were lower than 20%. The method showed limits of detection (LODs) and limits of quantification (LOQs) ranging from 0.1 to 2.0μgkg(-1) and from 0.5 to 5.0μgkg(-1), respectively. Finally, 25 real samples from Poland have been analyzed, and only 4-tertoctylphenol was detected at concentrations up to 8.9μgkg(-1) of soil dry weight. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative analysis of sitagliptin using the (19)F-NMR method: a universal technique for fluorinated compound detection.

PubMed

Zhang, Fen-Fen; Jiang, Meng-Hong; Sun, Lin-Lin; Zheng, Feng; Dong, Lei; Shah, Vishva; Shen, Wen-Bin; Ding, Ya

2015-01-07

To expand the application scope of nuclear magnetic resonance (NMR) technology in quantitative analysis of pharmaceutical ingredients, (19)F nuclear magnetic resonance ((19)F-NMR) spectroscopy has been employed as a simple, rapid, and reproducible approach for the detection of a fluorine-containing model drug, sitagliptin phosphate monohydrate (STG). ciprofloxacin (Cipro) has been used as the internal standard (IS). Influential factors, including the relaxation delay time (d1) and pulse angle, impacting the accuracy and precision of spectral data are systematically optimized. Method validation has been carried out in terms of precision and intermediate precision, linearity, limit of detection (LOD) and limit of quantification (LOQ), robustness, and stability. To validate the reliability and feasibility of the (19)F-NMR technology in quantitative analysis of pharmaceutical analytes, the assay result has been compared with that of (1)H-NMR. The statistical F-test and student t-test at 95% confidence level indicate that there is no significant difference between these two methods. Due to the advantages of (19)F-NMR, such as higher resolution and suitability for biological samples, it can be used as a universal technology for the quantitative analysis of other fluorine-containing pharmaceuticals and analytes.

Microemulsion Liquid Chromatographic Method for Simultaneous Determination of Simvastatin and Ezetimibe in Their Combined Dosage Forms

PubMed Central

Hammouda, Mohammed E. A.; Abu El-Enin, Mohamed A.; El-Sherbiny, Dina T.; El-Wasseef, Dalia R.; El-Ashry, Saadia M.

2013-01-01

A rapid HPLC procedure using a microemulsion as an eluent was developed and validated for analytical quality control of antihyperlipidemic mixture containing simvastatin (SIM) and ezetimibe (EZT) in their pharmaceutical preparations. The separation was performed on a column packed with cyano bonded stationary phase adopting UV detection at 238 nm using a flow rate of 1 mL/min. The optimized microemulsion mobile phase consisted of 0.2 M sodium dodecyl sulphate, 1% octanol, 10% n-propanol, and 0.3% triethylamine in 0.02 M phosphoric acid at pH 5.0. The developed method was validated in terms of specificity, linearity, lower limit of quantification (LOQ), lower limit of detection (LOD), precision, and accuracy. The proposed method is rapid (8.5 min), reproducible (RSD < 2.0%) and achieves satisfactory resolution between SIM and EZT (resolution factor = 2.57). The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from a reference method, as revealed by statistical analysis of the obtained results using Student's t-test and the variance ratio F-test. PMID:24282651

Multicomponent analysis of fat- and water-soluble vitamins and auxiliary substances in multivitamin preparations by qNMR.

PubMed

Eiff, Julia; Monakhova, Yulia B; Diehl, Bernd W K

2015-04-01

A nuclear magnetic resonance (NMR) spectroscopic method was tested to control 12 vitamins and accompanying substances in multivitamin preparations. The limits of detection (LODs) and limits of quantification (LOQs) varied in the 9.0-77.0 mg/kg and in the 34.5-93.5 mg/kg range, respectively. The coefficients of variation (CVs) ranged between 0.9% and 12%. The (1)H NMR spectra showed linearity for the 140-260 mg sample weight (R(2) > 0.918). The NMR spectra of multivitamin preparations showed the presence of different degradation products of ascorbic acid. The NMR method was applied to 13 different multivitamin preparations including tablets, capsules, and effervescent tablets with average recovery rates between 85% and 132%. A number of accompanying substances (citric acid, mannitol, saccharin, cyclamate, sum of steviol glycosides, and butylhydroxytoluene) were additionally identified and quantified. NMR was found to be suitable for the simultaneous qualitative measurement of water- and fat-soluble vitamins and accompanying substances and shows some promise for quantitative determination of at least 5 vitamins (B1, B3, B5, B6, and E) in multivitamin preparations.

Multi-site analytical evaluation of the Abbott ARCHITECT tacrolimus assay.

PubMed

Wallemacq, Pierre; Goffinet, Jean-Sebastien; O'Morchoe, Susan; Rosiere, Thomas; Maine, Gregory T; Labalette, Myriam; Aimo, Giuseppe; Dickson, Diana; Schmidt, Ed; Schwinzer, Reinhard; Schmid, Rainer W

2009-04-01

The objective of this study was to evaluate the analytical performance of the Abbott ARCHITECT Tacrolimus immunoassay. Proficiency panels and specimens from a population of organ transplant recipients were analyzed in 6 clinical laboratories in Europe and the United States, and the results were compared with other methods. The ARCHITECT assay requires a whole blood specimen pretreatment step with methanol/zinc sulfate to precipitate protein and extract the drug, followed by a 30-minute immunoassay using anti-tacrolimus antibody-coated paramagnetic microparticles and an acridinium-tacrolimus tracer. The assay was free from hematocrit interference in the range 25%-55% and from interference by extremes of cholesterol, triglycerides, bilirubin, total protein, and uric acid. The total percent of coefficient of variations of the assay were 4.9%-7.6% at 3 ng/mL, 2.9%-4.6% at 8.6 ng/mL, and 3.1%-8.2% at 15.5 ng/mL. Limit of detection was < or =0.5 ng/mL and limit of quantification (LOQ) ranged from 0.69 to 1.07 ng/mL across the 6 sites (based on the upper 95% confidence interval concentrations). The 2007 European Consensus Conference on Tacrolimus Optimization recommended the use of assay methods with an LOQ around 1 ng/mL, based upon the need to measure trough tacrolimus blood concentrations precisely down to 3 ng/mL during low-dose tacrolimus regimens. Tacrolimus International Proficiency Testing Scheme samples were measured by the ARCHITECT immunoassay at 5 sites and showed an average bias of -0.28 to +0.85 ng/mL versus IMx Tacrolimus II immunoassay historical values and -0.21 to +0.68 ng/mL versus liquid chromatography/tandem mass spectrometry (LC-MSMS) Tacrolimus historical values. Method comparison studies were performed with the ARCHITECT Tacrolimus immunoassay on patient specimens with the following results: ARCHITECT Tacrolimus assay versus the Abbott IMx Tacrolimus II immunoassay (4 sites) yielded average biases between -0.94 and +0.26 ng/mL; ARCHITECT assay versus the Dade Dimension Tacrolimus immunoassay (2 sites) yielded average biases of -0.46 and +0.11 ng/mL; and ARCHITECT assay versus LC-MSMS methods at 2 sites yielded average biases of +0.51 and +1.63 ng/mL. Spearman correlation coefficients were >/=0.90 on all method comparisons. The ARCHITECT Tacrolimus assay is a semiautomated, robust, and highly sensitive immunoassay, representing an alternative approach for laboratories not equipped with LC-MSMS, and meets the 1 ng/mL recommendation of LOQ by the European Consensus Conference on Tacrolimus Optimization.

Development and Validation of High Performance Liquid Chromatography Method for Determination Atorvastatin in Tablet

NASA Astrophysics Data System (ADS)

Yugatama, A.; Rohmani, S.; Dewangga, A.

2018-03-01

Atorvastatin is the primary choice for dyslipidemia treatment. Due to patent expiration of atorvastatin, the pharmaceutical industry makes copy of the drug. Therefore, the development methods for tablet quality tests involving atorvastatin concentration on tablets needs to be performed. The purpose of this research was to develop and validate the simple atorvastatin tablet analytical method by HPLC. HPLC system used in this experiment consisted of column Cosmosil C18 (150 x 4,6 mm, 5 µm) as the stationary reverse phase chomatography, a mixture of methanol-water at pH 3 (80:20 v/v) as the mobile phase, flow rate of 1 mL/min, and UV detector at wavelength of 245 nm. Validation methods were including: selectivity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). The results of this study indicate that the developed method had good validation including selectivity, linearity, accuracy, precision, LOD, and LOQ for analysis of atorvastatin tablet content. LOD and LOQ were 0.2 and 0.7 ng/mL, and the linearity range were 20 - 120 ng/mL.

Multiclass mycotoxin analysis in edible oils using a simple solvent extraction method and liquid chromatography with tandem mass spectrometry.

PubMed

Eom, Taeyong; Cho, Hyun-Deok; Kim, Junghyun; Park, Mihee; An, Jinyoung; Kim, Moosung; Kim, Sheen-Hee; Han, Sang Beom

2017-11-01

A simple and rapid method for the simultaneous determination of 11 mycotoxins - aflatoxins B 1 , B 2 , G 1 and G 2 ; fumonisins B 1 , B 2 and B 3 ; ochratoxin A; zearalenone; deoxynivalenol; and T-2 toxin - in edible oils was established using liquid chromatography tandem mass spectrometry (LC-MS/MS). In this study, QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe), QuEChERS with dispersive liquid-liquid microextraction, and solvent extraction were examined for sample preparation. Among these methods, solvent extraction with a mixture of formic acid/acetonitrile (5/95, v/v) successfully extracted all target mycotoxins. Subsequently, a defatting process using n-hexane was employed to remove the fats present in the edible oil samples. Mass spectrometry was carried out using electrospray ionisation in polarity switching mode with multiple reaction monitoring. The developed LC-MS/MS method was validated by assessing the specificity, linearity, recovery, limit of quantification (LOQ), accuracy and precision with reference to Commission Regulation (EC) 401/2006. Mycotoxin recoveries of 51.6-82.8% were achieved in addition to LOQs ranging from 0.025 ng/g to 1 ng/g. The edible oils proved to be relatively uncomplicated matrices and the developed method was applied to 9 edible oil samples, including soybean oil, corn oil and rice bran oil, to evaluate potential mycotoxin contamination. The levels of detection were significantly lower than the international regulatory standards. Therefore, we expect that our developed method, based on simple, two-step sample preparation process, will be suitable for the large-scale screening of mycotoxin contamination in edible oils.

Stereoselective method to quantify bupropion and its three major metabolites, hydroxybupropion, erythro-dihydrobupropion, and threo-dihydrobupropion using HPLC-MS/MS.

PubMed

Masters, Andrea R; McCoy, Michael; Jones, David R; Desta, Zeruesenay

2016-03-15

Bupropion metabolites formed via oxidation and reduction exhibit pharmacological activity, but little is known regarding their stereoselective disposition. A novel stereoselective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to separate and quantify enantiomers of bupropion, 4-hydroxybupropion, and erythro- and threo-dihydrobupropion. Liquid-liquid extraction was implemented to extract all analytes from 50 μL human plasma. Acetaminophen (APAP) was used as an internal standard. The analytes were separated on a Lux 3 μ Cellulose-3 250×4.6 mm column by methanol: acetonitrile: ammonium bicarbonate: ammonium hydroxide gradient elution and monitored using an ABSciex 5500 QTRAP triple-quadrupole mass spectrometer equipped with electrospray ionization probe in positive mode. Extraction efficiency for all analytes was ≥70%. The stability at a single non-extracted concentration for over 48 h at ambient temperature resulted in less than 9.8% variability for all analytes. The limit of quantification (LOQ) for enantiomers of bupropion and 4-hydroxybupropion was 0.3 ng/mL, while the LOQ for enantiomers of erythro- and threo-hydrobupropion was 0.15 ng/mL. The intra-day precision and accuracy estimates for enantiomers of bupropion and its metabolites ranged from 3.4% to 15.4% and from 80.6% to 97.8%, respectively, while the inter-day precision and accuracy ranged from 6.1% to 19.9% and from 88.5% to 99.9%, respectively. The current method was successfully implemented to determine the stereoselective pharmacokinetics of bupropion and its metabolites in 3 healthy volunteers administered a single 100mg oral dose of racemic bupropion. This novel, accurate, and precise HPLC-MS/MS method should enhance further research into bupropion stereoselective metabolism and drug interactions. Copyright © 2016 Elsevier B.V. All rights reserved.

Monitoring of polycyclic aromatic hydrocarbons (PAH) in food supplements containing botanicals and other ingredients on the Dutch market.

PubMed

Martena, M J; Grutters, M M P; De Groot, H N; Konings, E J M; Rietjens, I M C M

2011-01-01

Food supplements can contain polycyclic aromatic hydrocarbons (PAH). The European Food Safety Authority (EFSA) has defined 16 priority PAH that are both genotoxic and carcinogenic and identified eight priority PAH (PAH8) or four of these (PAH4) as good indicators of the toxicity and occurrence of PAH in food. The current study aimed to determine benzo[a]pyrene and other EFSA priority PAH in different categories of food supplements containing botanicals and other ingredients. From 2003 to 2008, benzo[a]pyrene exceeded the limit of quantification (LOQ) in 553 (44%) of 1258 supplements with a lower-bound mean of 3.37 µg kg(-1). In 2008 and 2009, benzo[a]pyrene and 12 other EFSA priority PAH were determined in 333 food supplements. Benzo[a]pyrene exceeded the LOQ in 210 (63%) food supplements with a lower-bound mean of 5.26 µg kg(-1). Lower-bound mean levels for PAH4 and PAH8(-indeno[1,2,3-cd]pyrene) were 33.5 and 40.5 µg kg(-1), respectively. Supplements containing resveratrol, Ginkgo biloba, St. John's wort and propolis showed relatively high PAH4 levels in 2008 and 2009. Before 2008, supplements with these ingredients and also dong quai, green tea or valerian contained relatively high benzo[a]pyrene levels. On average, PAH4 intake resulting from food supplement use will be at the lower end of the range of contributions of main food groups to PAH4 exposure, although individual food supplements can contribute significantly to PAH4 exposure. Regular control of EFSA indicator PAH levels in food supplements may prove a way forward to reduce further the intake of PAH from food.

New sorbent in the dispersive solid phase extraction step of quick, easy, cheap, effective, rugged, and safe for the extraction of organic contaminants in drinking water treatment sludge.

PubMed

Cerqueira, Maristela B R; Caldas, Sergiane S; Primel, Ednei G

2014-04-04

Recent studies have shown a decrease in the concentration of pesticides, pharmaceuticals and personal care products (PCPs) in water after treatment. A possible explanation for this phenomenon is that these compounds may adhere to the sludge; however, investigation of these compounds in drinking water treatment sludge has been scarce. The sludge generated by drinking water treatment plants during flocculation and decantation steps should get some special attention not only because it has been classified as non-inert waste but also because it is a very complex matrix, consisting essentially of inorganic (sand, argil and silt) and organic (humic substances) compounds. In the first step of this study, three QuEChERS methods were used, and then compared, for the extraction of pesticides (atrazine, simazine, clomazone and tebuconazole), pharmaceuticals (amitriptyline, caffeine, diclofenac and ibuprofen) and PCPs (methylparaben, propylparaben, triclocarban and bisphenol A) from drinking water treatment sludge. Afterwards, the study of different sorbents in the dispersive solid phase extraction (d-SPE) step was evaluated. Finally, a new QuEChERS method employing chitin, obtained from shrimp shell waste, was performed in the d-SPE step. After having been optimized, the method showed limits of quantification (LOQ) between 1 and 50 μg kg(-1) and the analytical curves showed r values higher than 0.98, when liquid chromatography tandem mass spectrometry was employed. Recoveries ranged between 50 and 120% with RSD≤15%. The matrix effect was evaluated and compensated with matrix-matched calibration. The method was applied to drinking water treatment sludge samples and methylparaben and tebuconazole were found in concentration

Design of a compressed air modulator to be used in comprehensive multidimensional gas chromatography and its application in the determination of pesticide residues in grapes.

PubMed

Pizzutti, Ionara R; Vreuls, René J J; de Kok, André; Roehrs, Rafael; Martel, Samile; Friggi, Caroline A; Zanella, Renato

2009-04-10

In this study, a new modulator that is simple, robust and presents low operation costs, was developed. This modulator uses compressed air to cool two small portions in the first centimeters of the second chromatographic column of a comprehensive multidimensional gas chromatography (GCxGC) system. The results show a variation in the peak area less than 3 and 5% to alkanes and pesticides, respectively. The standard deviations for the retention times in the first and second dimension are around 0.05 min and 0.05s for all the compounds. The system was optimized with n-alkanes. The GCxGC system proposed was applied in the determination of pyrethroid pesticides (bifenthrin, cypermethrin, deltamethrin, fenvalerate, esfenvalerate, cis- and trans-permethrin) in grape samples. Samples were extracted by the mini-Luke modified method and pesticides were quantified by comprehensive multidimensional gas chromatography with micro electron-capture detection (microECD). The values of method limit of quantification (LOQ) were 0.01-0.02 mg kg(-1) for all studied pyrethroid and the values of recovery were between 94.3 and 115.2%, with good precision (RSD<18.4%), demonstrating that the performance of the total method consisting of a modified Luke extraction method and determination by GCxGC-microECD are satisfactory. This study also showed that the system using a modulator with a double jet of compressed air has the potential for application in the analysis of a wider range of pesticide residues in other commodities since it provides low values of LOQ with acceptable accuracy and precision.

Determination of copper and mercury in phosphate fertilizers employing direct solid sampling analysis and high resolution continuum source graphite furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

de Oliveira Souza, Sidnei; François, Luciane Luiza; Borges, Aline Rocha; Vale, Maria Goreti Rodrigues; Araujo, Rennan Geovanny Oliveira

2015-12-01

The present study proposes the determination of copper and mercury in phosphate fertilizers by direct solid sampling analysis (SS) employing high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). For Cu determination, two analytical lines were used: 327.3960 nm and 249.2146 nm. Hg determination was carried out on the line 253.6521 nm and 100 μg KMnO4 was used as chemical modifier. The optimal pyrolysis temperature for Cu determination was 1300 °C. Atomization temperatures for Cu and Hg were 2400 and 1100 °C, respectively. External calibration with aqueous standard solutions was adopted for both elements. The limits of quantification (LoQs) and characteristic mass (m0) obtained for Cu determination were 0.4 μg g- 1 and 1.12 ng, respectively, on line 249.2146 nm, and 64 μg g- 1 and 25 pg on 327.3960 nm. For mercury, LoQ and m0 were 4.8 ng g- 1 and 39 pg, respectively. The accuracy of the proposed methods was confirmed by the analysis of standard reference material (SRM) of Trace Elements in Multi-Nutrient Fertilizer (SRM NIST 695). The precision expressed as relative standard deviation (RSD), was better than 8.2% for Hg and 7.7% for the Cu (n = 5), considered satisfactory for microanalysis in solid sample. Four fertilizer samples acquired in commercial establishments in the city of Salvador, Bahia, Brazil, were analyzed. The optimized analytical methods were simple, fast, accurate, precise and free of spectral interferences for the determination of Cu and Hg in phosphate fertilizer samples by SS-HR-CS GF AAS, avoiding the dissolution of the sample, the use of harmful reagents and the generation of residues.

Validation and Application of a Dried Blood Spot Ceftriaxone Assay

PubMed Central

Page-Sharp, Madhu; Nunn, Troy; Salman, Sam; Moore, Brioni R.; Batty, Kevin T.; Davis, Timothy M. E.

2015-01-01

Dried blood spot (DBS) antibiotic assays can facilitate pharmacokinetic/pharmacodynamic (PK/PD) studies in situations where venous blood sampling is logistically and/or ethically problematic. In this study, we aimed to develop, validate, and apply a DBS ceftriaxone assay. A liquid chromatography-tandem mass spectroscopy (LC-MS/MS) DBS ceftriaxone assay was assessed for matrix effects, process efficiency, recovery, variability, and limits of quantification (LOQ) and detection (LOD). The effects of hematocrit, protein binding, red cell partitioning, and chad positioning were evaluated, and thermal stability was assessed. Plasma, DBS, and cell pellet ceftriaxone concentrations in 10 healthy adults were compared, and plasma concentration-time profiles of DBS and plasma ceftriaxone were incorporated into population PK models. The LOQ and LOD for ceftriaxone in DBS were 0.14 mg/liter and 0.05 mg/liter, respectively. Adjusting for hematocrit, red cell partitioning, and relative recovery, DBS-predicted plasma concentrations were comparable to measured plasma concentrations (r > 0.95, P < 0.0001), and Bland-Altman plots showed no significant bias. The final population PK estimates of clearance, volume of distribution, and time above threshold MICs for measured and DBS-predicted plasma concentrations were similar. At 35°C, 21°C, 4°C, −20°C, and −80°C, ceftriaxone retained >95% initial concentrations in DBS for 14 h, 35 h, 30 days, 21 weeks, and >11 months, respectively. The present DBS ceftriaxone assay is robust and can be used as a surrogate for plasma concentrations to provide valid PK and PK/PD data in a variety of clinical situations, including in studies of young children and of those in remote or resource-poor settings. PMID:26438505

A simple and rapid chromatographic method to determine unauthorized basic colorants (rhodamine B, auramine O, and pararosaniline) in processed foods.

PubMed

Tatebe, Chiye; Zhong, Xining; Ohtsuki, Takashi; Kubota, Hiroki; Sato, Kyoko; Akiyama, Hiroshi

2014-09-01

A simple and rapid high-performance liquid chromatography (HPLC) method to determine basic colorants such as pararosaniline (PA), auramine O (AO), and rhodamine B (RB) in various processed foods was developed. Linearity of the calibration curves ranged from 0.05 to 50 μg/mL for PA and 0.05-100 μg/mL for AO and RB. The detection and quantification limits (LOD and LOQ) of the basic colorants, which were evaluated as signal-to-noise ratios of 3 for LOD and 10 for LOQ, ranged from 0.0125 to 0.05 and 0.025 to 0.125 μg/g, respectively. The recoveries and relative standard deviations of three basic colorants in six processed foods, namely, chili sauce, curry paste, gochujang (hot pepper paste), tandoori chicken (roasted chicken prepared with yogurt and spices), powder soup, and shrimp powder ranged from 70.2% to 102.8% and 0.8% to 8.0%, respectively. The intraday precision of the recovery test ranged from 1.7% to 4.5%, whereas the interday precision ranged from 3.7% to 7.7%. The reported method has been successfully applied to basic colorant determination in various processed foods such as fat-based food matrices (curry paste and tandoori chicken), chili products (gochujang and chili sauce), and protein-based products (shrimp powder and powder soup). Thin layer chromatography and liquid chromatography/mass spectrometry methods for the determination of basic colorants in processed foods were also developed for rapid analysis and identification, respectively. These methods are very useful for monitoring unauthorized basic colorants in inspection centers or quarantine laboratories in many countries.

Trace analysis of sulforaphane in bee pollen and royal jelly by liquid chromatography-tandem mass spectrometry.

PubMed

Ares, Ana M; Ayuso, Irene; Bernal, José L; Nozal, María J; Bernal, José

2016-02-15

In this study, we investigate for the first time the presence of sulforaphane (SFN) residues in two of the most currently consumed food/dietary supplements, royal jelly and bee pollen. Chromatography-tandem mass spectrometry (LC-MS/MS) was the method employed, the mass spectrometer consisting of an ion-trap mass analyzer used with electrospray ionization (ESI) in positive ion mode. An efficient sample treatment involving a solvent extraction with methanol, centrifugation, and concentration in a rotary evaporator was proposed. In all cases average analyte recoveries were between 92 and 106%. Chromatographic analysis (16min) was performed on a core-shell technology based column (Kinetex C18, 150×4.6mm, 2.6μm, 100Å). The mobile phase consisted of 0.02M ammonium formate in water and acetonitrile, with a flow rate of 0.5mL/min in gradient elution mode. The fully validated method was selective, linear from 8 to 1000μg/kg (bee pollen), or from 10 to 1250μg/kg (royal jelly), precise and accurate; relative standard deviation (% RSD) and relative error (% RE) values were below 10%. Low limits of detection (LOD) and quantification (LOQ) were obtained, namely, 3μg/kg (LOD) and 8 (bee pollen) and 10 (royal jelly) μg/kg (LOQ). The method was applied for SFN analysis in several royal jelly and bee pollen samples. SFN was detected at trace levels in some bee pollen samples (<23μg/kg) examined, whilst SFN went undetected in the royal jelly samples analyzed. Copyright © 2016 Elsevier B.V. All rights reserved.

Simultaneous determination of perfluoroalkyl iodides, perfluoroalkane sulfonamides, fluorotelomer alcohols, fluorotelomer iodides and fluorotelomer acrylates and methacrylates in water and sediments using solid-phase microextraction-gas chromatography/mass spectrometry.

PubMed

Bach, Cristina; Boiteux, Virginie; Hemard, Jessica; Colin, Adeline; Rosin, Christophe; Munoz, Jean-François; Dauchy, Xavier

2016-05-27

Here, we developed and validated a headspace-solid-phase microextraction-gas chromatography/mass spectrometry (HS-SPME-GC/MS) method for the determination of 14 volatile perfluorinated alkylated substances (PFASs) in water and sediment samples according to SANTE 11945/2015 guidelines. Three fluorotelomer alcohols (FTOHs), two perfluoroalkyl iodides (PFIs), three fluorotelomer iodides (FTIs), four fluorotelomer acrylates and methacrylates (FTACs and FTMACs) and two perfluoroalkyl sulfonamides (FASAs) were analysed simultaneously to assess the occurrence of these compounds from their emission sources to the outlets in water treatment plants. Several SPME parameters were optimised for both water and sediment to maximise responses and keep analysis time to a minimum. In tap water, the limits of quantification (LOQs) were found to be between 20ng/L and 100ng/L depending on the analyte, with mean recoveries ranging from 76 to 126%. For sediments, LOQs ranged from 1 to 3ng/g dry weight depending on the target compound, with mean recoveries ranging from 74 to 125%. SPME considerably reduced sample preparation time and its use provided a sensitive, fast and simple technique. We then used this HS-SPME-GC/MS method to investigate the presence of volatile PFASs in the vicinity of an industrial facility. Only 8:2 FTOH and 10:2 FTOH were detected in a few water and sediment samples at sub-ppb concentration levels. Moreover, several non-target fluorotelomers (12:2 FTOH, 14:2 FTOH and 10:2 FTI) were identified in raw effluent samples. These long-chain fluorotelomers have high bioaccumulative potential in the aquatic environment compared with short-chain fluorotelomers such as 6:2 FTOH and 6:2 FTI. Copyright © 2016 Elsevier B.V. All rights reserved.

Perfluoroalkyl Acid Concentrations in Livers of Fox (Vulpes vulpes) and Chamois (Rupicapra rupicapra) from Germany and Austria.

PubMed

Riebe, Rika Alessa; Falk, Sandy; Georgii, Sebastian; Brunn, Hubertus; Failing, Klaus; Stahl, Thorsten

2016-07-01

The concentrations of 11 perfluorinated alkyl acids (PFAAs) were measured in the livers of foxes (Vulpes vulpes) from Germany, a primarily carnivorous species, and chamois (Rupicapra rupicapra) from Austria, an herbivorous species. Perfluorooctanesulfonate (PFOS) at concentrations [all results refer to wet weight (ww)] of 3.2-320 µg/kg were detected in all 40 fox livers tested, yielding an arithmetic mean of 46.6 µg/kg and a median of 29.8 µg/kg. Long-chain PFAAs were detected at concentrations of 1.7 µg/kg perfluorononanoic acid (PFNA) to 2.4 µg/kg perfluorodecanoic acid (PFDA) and perfluorododecanoic acid (PFDoDA). Of the short-chain PFAAs tested, only perfluorohexanoic acid (PFHxA) was found in 1 fox liver at a concentration of 1.4 µg/kg, and perfluorohexane sulfonate (PFHxS) was found in 2 fox livers at a concentration of 1 µg/kg each. PFOS and PFNA concentrations higher than limit of quantification (LOQ) were detected in 90.9 and 81.8 % of chamois livers, respectively. The arithmetic mean for PFOS concentrations was 2.2 µg/kg (median 2.4 µg/kg), a factor of 21 (median factor of 12) lower than in fox livers. The arithmetic mean for PFNA concentrations was 2.0 µg/kg (median 1.9 µg/kg). Perfluorobutanoic acid, PFHxA, perfluorooctanoic acid, perfluorobutanesulfonate, and PFHxS were not detected at concentrations higher than the LOQ in any of the samples. The various results are compared with one another and with the results of other studies of herbivorous, carnivorous, and omnivorous wild animals. The highest concentrations of PFAA, in particular PFOS, were found in omnivorous animals followed by carnivores. The lowest levels were present in herbivores.

Method development for the control determination of mercury in seafood by solid-sampling thermal decomposition amalgamation atomic absorption spectrometry (TDA AAS).

PubMed

Torres, D P; Martins-Teixeira, M B; Silva, E F; Queiroz, H M

2012-01-01

A very simple and rapid method for the determination of total mercury in fish samples using the Direct Mercury Analyser DMA-80 was developed. In this system, a previously weighted portion of fresh fish is combusted and the released mercury is selectively trapped in a gold amalgamator. Upon heating, mercury is desorbed from the amalgamator, an atomic absorption measurement is performed and the mercury concentration is calculated. Some experimental parameters have been studied and optimised. In this study the sample mass was about 100.0 mg. The relative standard deviation was lower than 8.0% for all measurements of solid samples. Two calibration curves against aqueous standard solutions were prepared through the low linear range from 2.5 to 20.0 ng of Hg, and the high linear range from 25.0 to 200.0 ng of Hg, for which a correlation coefficient better than 0.997 was achieved, as well as a normal distribution of the residuals. Mercury reference solutions were prepared in 5.0% v/v nitric acid medium. Lyophilised fish tissues were also analysed; however, the additional procedure had no advantage over the direct analysis of the fresh fish, and additionally increased the total analytical process time. A fish tissue reference material, IAEA-407, was analysed and the mercury concentration was in agreement with the certified value, according to the t-test at a 95% confidence level. The limit of quantification (LOQ), based on a mercury-free sample, was 3.0 µg kg(-1). This LOQ is in accordance with performance criteria required by the Commission Regulation No. 333/2007. Simplicity and high efficiency, without the need for any sample preparation procedure, are some of the qualities of the proposed method.

Application of analytical quality by design principles for the determination of alkyl p-toluenesulfonates impurities in Aprepitant by HPLC. Validation using total-error concept.

PubMed

Zacharis, Constantinos K; Vastardi, Elli

2018-02-20

In the research presented we report the development of a simple and robust liquid chromatographic method for the quantification of two genotoxic alkyl sulphonate impurities (namely methyl p-toluenesulfonate and isopropyl p-toluenesulfonate) in Aprepitant API substances using the Analytical Quality by Design (AQbD) approach. Following the steps of AQbD protocol, the selected critical method attributes (CMAs) were the separation criterions between the critical peak pairs, the analysis time and the peak efficiencies of the analytes. The critical method parameters (CMPs) included the flow rate, the gradient slope and the acetonitrile content at the first step of the gradient elution program. Multivariate experimental designs namely Plackett-Burman and Box-Behnken designs were conducted sequentially for factor screening and optimization of the method parameters. The optimal separation conditions were estimated using the desirability function. The method was fully validated in the range of 10-200% of the target concentration limit of the analytes using the "total error" approach. Accuracy profiles - a graphical decision making tool - were constructed using the results of the validation procedures. The β-expectation tolerance intervals did not exceed the acceptance criteria of±10%, meaning that 95% of future results will be included in the defined bias limits. The relative bias ranged between - 1.3-3.8% for both analytes, while the RSD values for repeatability and intermediate precision were less than 1.9% in all cases. The achieved limit of detection (LOD) and the limit of quantification (LOQ) were adequate for the specific purpose and found to be 0.02% (corresponding to 48μgg -1 in sample) for both methyl and isopropyl p-toluenesulfonate. As proof-of-concept, the validated method was successfully applied in the analysis of several Aprepitant batches indicating that this methodology could be used for routine quality control analyses. Copyright © 2017 Elsevier B.V. All rights reserved.

Validation of QuEChERS analytical technique for organochlorines and synthetic pyrethroids in fruits and vegetables using GC-ECD.

PubMed

Dubey, J K; Patyal, S K; Sharma, Ajay

2018-03-19

In the present day scenario of increasing awareness and concern about the pesticides, it is very important to ensure the quality of data being generated in pesticide residue analysis. To impart confidence in the products, terms like quality assurance and quality control are used as an integral part of quality management. In order to ensure better quality of results in pesticide residue analysis, validation of analytical methods to be used is extremely important. Keeping in view the importance of validation of method, the validation of QuEChERS (quick, easy, cheap, effective, rugged, and safe) a multiresidue method for extraction of 13 organochlorines and seven synthetic pyrethroids in fruits and vegetables followed by GC ECD for quantification was done so as to use this method for analysis of samples received in the laboratory. The method has been validated as per the Guidelines issued by SANCO (French words Sante for Health and Consommateurs for Consumers) in accordance with their document SANCO/XXXX/2013. Various parameters analyzed, viz., linearity, specificity, repeatability, reproducibility, and ruggedness were found to have acceptable values with a per cent RSD of less than 10%. Limit of quantification (LOQ) for the organochlorines was established to be 0.01 and 0.05 mg kg -1 for the synthetic pyrethroids. The uncertainty of the measurement (MU) for all these compounds ranged between 1 and 10%. The matrix-match calibration was used to compensate the matrix effect on the quantification of the compounds. The overall recovery of the method ranged between 80 and 120%. These results demonstrate the applicability and acceptability of this method in routine estimation of pesticide residues of these 20 pesticides in the fruits and vegetables by the laboratory.

Quantifying Residues from Postharvest Propylene Oxide Fumigation of Almonds and Walnuts.

PubMed

Jimenez, Leonel R; Hall, Wiley A; Rodriquez, Matthew S; Cooper, William J; Muhareb, Jeanette; Jones, Tom; Walse, Spencer S

2015-01-01

A novel analytical approach involving solvent extraction with methyl tert-butyl ether (MTBE) followed by GC was developed to quantify residues that result from the postharvest fumigation of almonds and walnuts with propylene oxide (PPO). Verification and quantification of PPO, propylene chlorohydrin (PCH) [1-chloropropan-2-ol (PCH-1) and 2-chloropropan-1-ol (PCH-2)], and propylene bromohydrin (PBH) [1-bromopropan-2-ol (PBH-1) and 2-bromopropan-1-ol (PBH-2)] was accomplished with a combination of electron impact ionization MS (EIMS), negative ion chemical ionization MS (NCIMS), and electron capture detection (ECD). Respective GC/EIMS LOQs for PPO, PCH-1, PCH-2, PBH-1, and PBH-2 in MTBE extracts were [ppm (μg/g nut)] 0.9, 2.1, 2.5, 30.3, and 50.0 for almonds and 0.8, 2.2, 2.02, 41.6, and 45.7 for walnuts. Relative to GC/EIMS, GC-ECD analyses resulted in no detection of PPO, similar detector responses for PCH isomers, and >100-fold more sensitive detection of PBH isomers. NCIMS did not enhance detection of PBH isomers relative to EIMS and was, respectively, approximately 20-, 5-, and 10-fold less sensitive to PPO, PCH-1, and PCH-2. MTBE extraction efficiencies were >90% for all analytes. The 10-fold concentration of MTBE extracts yielded recoveries of 85-105% for the PBH isomers and a concomitant decrease in LODs and LOQs across detector types. The recoveries of PCH isomers and PPO in the MTBE concentrate were relatively low (approximately 50 to 75%), which confound improvements in LODs and LOQs regardless of detector type.

Analytical procedure for the determination of very volatile organic compounds (C3-C6) in indoor air.

PubMed

Schieweck, Alexandra; Gunschera, Jan; Varol, Deniz; Salthammer, Tunga

2018-05-01

The substance group of very volatile organic compounds (VVOCs) is moving into the focus of indoor air analysis, facing ongoing regulations at international and European levels targeting on indoor air quality and human health. However, there exists at present no validated analysis for the identification and quantification of VVOCs in indoor air. Therefore, the present study targeted on the development of an analytical method in order to sample the maximum possible quantity of VVOCs in indoor air on solid sorbents with subsequent analysis by thermal desorption and coupled gas chromatography/mass spectrometry (TDS-GC/MS). For this purpose, it was necessary to investigate the performance of available sorbents and to optimize the parameters of GC/MS analysis. Stainless steel tubes filled with Carbograph 5TD were applied successfully for low-volume sampling (2-4 l) with minimal breakthrough (< 1%). With the developed method, VVOCs between C 3 and C 6 of different volatility and polarity  can be detected even in trace quantities with low limits of quantitation (LOQ; 1-3 μg m -3 ). Limitations occur for low molecular weight compounds ≤C 3 , especially for polar substances, such as carboxylic acids and for some aldehydes and alcohols. Consequently, established methods for the quantification of these compounds in indoor air cannot be fully substituted yet. At least three different analytical techniques are needed to cover the large spectrum of relevant VVOCs in indoor air. In addition, unexpected reaction products might occur and need to be taken into account to avoid misinterpretation of chromatographic signals. Graphical abstract Solid sorbent sampling of VVOCs (C 3 -C 6 ) in indoor air with subsequent TDS-GC/MS analysis.

[Simultaneous determination of seven high risk pesticide residues in royal jelly by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Li, Yinghong; Zhou, Ping; Xu, Quanhua; Zhao, Huan; Shao, Qiaoyun

2018-02-08

A method was developed for the simultaneous determination of seven high risk pesticides in the royal jelly, eg. tau-fluvalinate, triadimenol, coumaphos, haloxyfop, carbendazim, thiophanate-ethyl and thiophanate-methyl by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). First, the royal jelly samples were extracted with acetonitrile under alkaline conditions. After dehydration by anhydrous sodium sulfate, the extracts were enriched and purified through solid-phase extraction (SPE) with Oasis HLB cartridges. Finally, the pesticides were detected by HPLC-MS/MS method. The separation was carried out on a Venusil MP C18 column with gradient elution. Methanol (containing 0.1% (v/v) formic acid) and 0.5 mmol/L ammonium acetate aqueous solution (containing 0.1% (v/v) formic acid) were used as the mobile phases. The detection was achieved using electrospray ionization in positive ion (ESI + ) mode and multiple reaction monitoring (MRM) mode for data collection. Quantification was carried out using internal standard method. The results showed that the seven high risk pesticides were linear in the range of 5-100 μg/kg. The linear correlation coefficients ( r 2 ) were 0.9921-0.9996. The limits of detection (LODs) and limits of quantification (LOQs) of the seven high risk pesticides were 0.5-2.0 μg/kg and 1.0-5.0 μg/kg, respectively. The average recoveries at the three spiked levels were 80.5%-101.3%, and the relative standard deviations were 3.6%-9.4% ( n =3). This method is simple, effective and sensitive, and is suitable for the determination of the pesticide residues in royal jelly.

Electrosynthesis and characterization of nanostructured polyquinone for use in detection and quantification of naturally occurring dsDNA.

PubMed

Hernández, Loreto A; Del Valle, María A; Armijo, Francisco

2016-05-15

The detection of naturally occurring desoxyribonucleic acid (DNA) has become a subject of study by the projections that would generate to be able to sense the genetic material for the detection of future diseases. Bearing this in mind, to provide new measuring strategies, in the current work the preparation of a low-cost electrode, modified with poly(1-amino-9,10-anthraquinone) nanowires using a SiO2 template, is carried out; the assembly is next modified by covalently attaching ssDNA strands. It must be noted that all this is accomplished by using solely electrochemical techniques, according to methodology developed for this purpose. SEM images of the modified surface show high order and homogeneity in the distribution of modified nanowires over the electrode surface. In turn, after the hybridization with its complementary strand, the voltammetric responses enable corroborating the linear relationship between hybridization at different DNA concentrations and normalized current response, obtaining a limit of detection (LOD) 5.7·10(-12)gL(-1) and limit of quantification (LOQ) 1.9·10(-11)gL(-1). The working dynamic range is between 1.4·10(-7) and 8.5·10(-9)gL(-1) with a correlation coefficient 0.9998. The successful obtaining of the modified electrode allows concluding that the high order reached by the nanostructures, guides the subsequent single strand of DNA (ssDNA) covalent attachment, which after hybridization with its complementary strand brings about a considerable current increase. This result allows foreseeing a guaranteed breakthrough with regard to the use of the biosensor in real samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Method validation for control determination of mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry.

PubMed

Torres, Daiane Placido; Martins-Teixeira, Maristela Braga; Cadore, Solange; Queiroz, Helena Müller

2015-01-01

A method for the determination of total mercury in fresh fish and shrimp samples by solid sampling thermal decomposition/amalgamation atomic absorption spectrometry (TDA AAS) has been validated following international foodstuff protocols in order to fulfill the Brazilian National Residue Control Plan. The experimental parameters have been previously studied and optimized according to specific legislation on validation and inorganic contaminants in foodstuff. Linearity, sensitivity, specificity, detection and quantification limits, precision (repeatability and within-laboratory reproducibility), robustness as well as accuracy of the method have been evaluated. Linearity of response was satisfactory for the two range concentrations available on the TDA AAS equipment, between approximately 25.0 and 200.0 μg kg(-1) (square regression) and 250.0 and 2000.0 μg kg(-1) (linear regression) of mercury. The residues for both ranges were homoscedastic and independent, with normal distribution. Correlation coefficients obtained for these ranges were higher than 0.995. Limits of quantification (LOQ) and of detection of the method (LDM), based on signal standard deviation (SD) for a low-in-mercury sample, were 3.0 and 1.0 μg kg(-1), respectively. Repeatability of the method was better than 4%. Within-laboratory reproducibility achieved a relative SD better than 6%. Robustness of the current method was evaluated and pointed sample mass as a significant factor. Accuracy (assessed as the analyte recovery) was calculated on basis of the repeatability, and ranged from 89% to 99%. The obtained results showed the suitability of the present method for direct mercury measurement in fresh fish and shrimp samples and the importance of monitoring the analysis conditions for food control purposes. Additionally, the competence of this method was recognized by accreditation under the standard ISO/IEC 17025.

Liquid chromatography-high resolution mass spectrometry (LC-HRMS) determination of stimulants, anorectic drugs and phosphodiesterase 5 inhibitors (PDE5I) in food supplements.

PubMed

Strano-Rossi, Sabina; Odoardi, Sara; Castrignanò, Erika; Serpelloni, Giovanni; Chiarotti, Marcello

2015-03-15

The paper describes a liquid chromatography/high resolution mass spectrometry LC/HRMS method for the simultaneous identification and quantification of stimulants (ephedrines, caffeine, anorectic drugs such as phentermine, phendimetrazine, phenmetrazine, fenfluramine, benfluorex, mephentermine, fencanfamine, sibutramine) and PDE5I (sildenafil, vardenafil and tadalafil) in food supplements using a benchtop Orbitrap mass spectrometer. The mass detector, with a nominal resolving power of 100,000 (FWHM at m/z 200), operated in full scan mode in ESI positive ionization mode. Analytes were identified by retention times, accurate masses and correspondence of experimental and calculated isotopic patterns. The limits of detection (LOD) obtained varied from 1 to 25 ng g(-1) and limits of quantification (LOQ) were 50 ng g(-1) for all compounds. The method was linear for all the analytes in the ranges from 50 to 2000 ng g(-1), giving correlation coefficients>0.99. Accuracy (intended as %E) and repeatability (% CV) were always lower than 15%. The method was applied to the analysis of 36 dietary supplements, revealing the presence of ephedrine and/or pseudoephedrine in four of them, caffeine in eight of them and sildenafil in four of them. In one case, ephedrine was not reported on the label of the dietary supplement, as well as for caffeine in other two cases. A further confirmation of the analytes identity in positive samples was obtained through in-source fragmentation and comparison of the obtained fragments and their relative abundances with those from certified standards. As the acquisition mode is full scan, it would be also possible to re-process a previously acquired datafile for the investigation of untargeted analytes. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of phenobarbital in hair matrix by liquid phase microextraction (LPME) and gas chromatography-mass spectrometry (GC-MS).

PubMed

Roveri, Flávia Lopes; Paranhos, Beatriz Aparecida Passos Bismara; Yonamine, Mauricio

2016-08-01

A method for identification and quantification of phenobarbital in hair samples by liquid phase microextraction (LPME) and gas chromatography-mass spectrometry (GC-MS) has been presented. Drug-free hair specimens were collected and separated in 50mg aliquots. Each aliquot was washed with 2.0mL of dichloromethane for 15min at 37°C. Standards and deuterated internal standards for calibration and quality control samples were added to the washed hair aliquot and the sample was submitted to complete digestion with sodium hydroxide (NaOH) 1.0mol/L for 15min at 70°C. The dissolved sample was submitted to LPME. After extraction, the residue was derivatized with tetramethylammonium hydroxide (TMAH) and analyzed by GC-MS. The limit of detection (LOD) was 0.1ng/mg and the limit of quantification (LOQ) was 0.25ng/mg. The calibration curve was linear over a concentration range of 0.25ng/mg to 10ng/mg (r(2)>0.99). The intra- and inter-assay precisions, given by RSD, were less than 6% for phenobarbital. Fortified samples of secobarbital and pentobarbital were also submitted to the validated method. The method was successfully applied to hair samples collected from three volunteers who reported regular use of phenobarbital (clinical treatment). The concentrations found were 9.5, 15.1 and 16.3ng/mg of phenobarbital. To contemplate the concentrations found, dilution integrity tests were also validated. The LPME and GC-MS method showed to be suitable for the detection of phenobarbital in hair samples and can be promptly used for different purposes whenever required. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Sensitive and selective liquid chromatography-tandem mass spectrometry method for the determination of five ganoderic acids in Ganoderma lucidum and its related species.

PubMed

Liu, Yongli; Liu, Youping; Qiu, Feng; Di, Xin

2011-03-25

The present paper describes a novel, sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous analysis of ganoderic acids C(2), B, A, H, D in Ganoderma lucidum and its related species. Ganoderma samples were prepared using simple ultrasonic extraction. Chromatographic separation was carried out on an Agilent Zorbax XDB C(18) column (250 mm × 4.6 mm i.d., 5μm) with an isocratic mobile phase consisting of acetonitrile, water and formic acid (42:58:0.5, v/v/v). Mass spectrometric detection was achieved by a triple-quadrupole mass spectrometer equipped with an atmospheric pressure chemical ionization (APCI) interface operating in negative and positive ionization mode via a single within-run polarity switching. Quantitation of five ganoderic acids was performed using selective reaction monitoring (SRM) mode. The intra- and inter-day precision was less than 6.2% and the accuracy ranged from 90.0% to 105.7%. The limit of quantification (LOQ) was 20.0-40.0 ng/mL and the limit of detection (LOD) was 3.0-25.0 ng/mL. With this method, low levels of ganoderic acids in the fruiting bodies of Ganoderma sinense and Ganoderma applanatum were accurately quantified for the first time. Importantly, the method allows unequivocal quantification of the five ganoderic acids in the spores and fruiting bodies of Ganoderma lucidum, whereas the previously published methods have lacked the capability. The method presented will be a powerful tool for quality control of Ganoderma lucidum and its related species. Copyright © 2010 Elsevier B.V. All rights reserved.

Measurement of yunaconitine and crassicauline A in small-volume blood serum samples by LC-MS/MS: tracing of aconite poisoning in clinical diagnosis.

PubMed

Ka-Wing Chung, Karen; Pak-Lam Chen, Sammy; Ng, Sau-Wah; Wing-Lai Mak, Tony; Sze-Yin Leung, Kelvin

2012-08-15

Aconite poisoning is one of the most serious types of herb-related medical emergencies. In Hong Kong, many if not most of these poisoning cases are due to confusion in herbal species; that is, the wrong herbs are used in prescriptions. Such human errors, while inevitable perhaps, can be serious, and sometimes fatal. The chemical components responsible for aconite poisoning are yunaconitine and crassicauline A. In the present study, a rapid and sensitive method for the screening and quantification of yunaconitine and crassicauline A in human serum, using LC-MS/MS, was developed and validated. Methyllycaconitine was chosen as the internal standard. The limit of detection (LOD) of yunaconitine and crassicauline A were found to be 0.022 and 0.021 ng/mL, respectively. The limit of quantification (LOQ) was 0.1 ng/mL for both yunaconitine and crassicauline A. The recovery of yunaconitine and crassicauline A ranged from 78.6% to 84.9% and 78.3% to 87.2%, respectively. The matrix effect of yunaconitine and crassicauline A ranged from 110.0% to 130.4% and 121.2 to 130.0%, respectively. Both yunaconitine and crassicauline A were stable in serum for at least 3 months at -20 °C, and the extracts were stable for at least 7 days. For clinical applications, serum samples of two patients confirmed to have had aconite herbs poisoning in 2008 were quantified using the developed method. The result showed that this method can be utilized in clinical routine applications. This screening method expedites the diagnosis in cases of suspected aconite poisoning, thus enabling doctors to treat the condition more quickly and effectively. Copyright © 2012 Elsevier B.V. All rights reserved.

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

PubMed

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

2017-07-01

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

Monitoring of noble, signal and narrow-clawed crayfish using environmental DNA from freshwater samples.

PubMed

Agersnap, Sune; Larsen, William Brenner; Knudsen, Steen Wilhelm; Strand, David; Thomsen, Philip Francis; Hesselsøe, Martin; Mortensen, Peter Bondgaard; Vrålstad, Trude; Møller, Peter Rask

2017-01-01

For several hundred years freshwater crayfish (Crustacea-Decapoda-Astacidea) have played an important ecological, cultural and culinary role in Scandinavia. However, many native populations of noble crayfish Astacus astacus have faced major declines during the last century, largely resulting from human assisted expansion of non-indigenous signal crayfish Pacifastacus leniusculus that carry and transmit the crayfish plague pathogen. In Denmark, also the non-indigenous narrow-clawed crayfish Astacus leptodactylus has expanded due to anthropogenic activities. Knowledge about crayfish distribution and early detection of non-indigenous and invasive species are crucial elements in successful conservation of indigenous crayfish. The use of environmental DNA (eDNA) extracted from water samples is a promising new tool for early and non-invasive detection of species in aquatic environments. In the present study, we have developed and tested quantitative PCR (qPCR) assays for species-specific detection and quantification of the three above mentioned crayfish species on the basis of mitochondrial cytochrome oxidase 1 (mtDNA-CO1), including separate assays for two clades of A. leptodactylus. The limit of detection (LOD) was experimentally established as 5 copies/PCR with two different approaches, and the limit of quantification (LOQ) were determined to 5 and 10 copies/PCR, respectively, depending on chosen approach. The assays detected crayfish in natural freshwater ecosystems with known populations of all three species, and show promising potentials for future monitoring of A. astacus, P. leniusculus and A. leptodactylus. However, the assays need further validation with data 1) comparing traditional and eDNA based estimates of abundance, and 2) representing a broader geographical range for the involved crayfish species.

Monitoring of noble, signal and narrow-clawed crayfish using environmental DNA from freshwater samples

PubMed Central

Knudsen, Steen Wilhelm; Strand, David; Thomsen, Philip Francis; Hesselsøe, Martin; Mortensen, Peter Bondgaard; Vrålstad, Trude; Møller, Peter Rask

2017-01-01

For several hundred years freshwater crayfish (Crustacea—Decapoda—Astacidea) have played an important ecological, cultural and culinary role in Scandinavia. However, many native populations of noble crayfish Astacus astacus have faced major declines during the last century, largely resulting from human assisted expansion of non-indigenous signal crayfish Pacifastacus leniusculus that carry and transmit the crayfish plague pathogen. In Denmark, also the non-indigenous narrow-clawed crayfish Astacus leptodactylus has expanded due to anthropogenic activities. Knowledge about crayfish distribution and early detection of non-indigenous and invasive species are crucial elements in successful conservation of indigenous crayfish. The use of environmental DNA (eDNA) extracted from water samples is a promising new tool for early and non-invasive detection of species in aquatic environments. In the present study, we have developed and tested quantitative PCR (qPCR) assays for species-specific detection and quantification of the three above mentioned crayfish species on the basis of mitochondrial cytochrome oxidase 1 (mtDNA-CO1), including separate assays for two clades of A. leptodactylus. The limit of detection (LOD) was experimentally established as 5 copies/PCR with two different approaches, and the limit of quantification (LOQ) were determined to 5 and 10 copies/PCR, respectively, depending on chosen approach. The assays detected crayfish in natural freshwater ecosystems with known populations of all three species, and show promising potentials for future monitoring of A. astacus, P. leniusculus and A. leptodactylus. However, the assays need further validation with data 1) comparing traditional and eDNA based estimates of abundance, and 2) representing a broader geographical range for the involved crayfish species. PMID:28654642

Long-Gradient Separations Coupled with Selected Reaction Monitoring for Highly Sensitive, Large Scale Targeted Protein Quantification in a Single Analysis

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

Shi, Tujin; Fillmore, Thomas L.; Gao, Yuqian

2013-10-01

Long-gradient separations coupled to tandem MS were recently demonstrated to provide a deep proteome coverage for global proteomics; however, such long-gradient separations have not been explored for targeted proteomics. Herein, we investigate the potential performance of the long-gradient separations coupled with selected reaction monitoring (LG-SRM) for targeted protein quantification. Direct comparison of LG-SRM (5 h gradient) and conventional LC-SRM (45 min gradient) showed that the long-gradient separations significantly reduced background interference levels and provided an 8- to 100-fold improvement in LOQ for target proteins in human female serum. Based on at least one surrogate peptide per protein, an LOQ ofmore » 10 ng/mL was achieved for the two spiked proteins in non-depleted human serum. The LG-SRM detection of seven out of eight endogenous plasma proteins expressed at ng/mL or sub-ng/mL levels in clinical patient sera was also demonstrated. A correlation coefficient of >0.99 was observed for the results of LG-SRM and ELISA measurements for prostate-specific antigen (PSA) in selected patient sera. Further enhancement of LG-SRM sensitivity was achieved by applying front-end IgY14 immunoaffinity depletion. Besides improved sensitivity, LG-SRM offers at least 3 times higher multiplexing capacity than conventional LC-SRM due to ~3-fold increase in average peak widths for a 300-min gradient compared to a 45-min gradient. Therefore, LG-SRM holds great potential for bridging the gap between global and targeted proteomics due to its advantages in both sensitivity and multiplexing capacity.« less

Occurrence of 3-MCPD and glycidyl esters in edible oils in the United States.

PubMed

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

2013-01-01

Fatty acid esters of 3-monochloropropanediol (3-MCPD) and glycidol are processing contaminants found in a wide range of edible oils. While both 3 MCPD and glycidol have toxicological properties that at present has concerns for food safety, the published occurrence data are limited. Occurrence information is presented for the concentrations of 3-MCPD and glycidyl esters in 116 retail and/or industrial edible oils and fats using LC-MS/MS analysis of intact esters. The concentrations for bound 3-MCPD ranged from below the limit of quantitation (

Psychoactive substances in seriously injured drivers in Denmark.

PubMed

Wiese Simonsen, K; Steentoft, A; Bernhoft, I M; Hels, T; Rasmussen, B S; Linnet, K

2013-01-10

This study assesses the presence of a number of psychoactive substances, including alcohol, based on blood samples from 840 seriously injured drivers admitted to five selected hospitals located in five different regions of Denmark. The study was a part of the EU 6th framework program DRUID (Driving Under the Influence of Drugs, Alcohol and Medicines). Blood samples were screened for 30 illegal and legal psychoactive substances and metabolites as well as ethanol. Danish legal limits were used to evaluate the frequency of drivers violating the Danish legislation while limit of quantification (LOQ) was used for monitoring positive drivers. Tramadol is not included in the Danish legislation therefore the general cut off, as decided in the DRUID project was used. Overall, ethanol (18%) was the most frequently identified compound (alone or in combination with other drugs) exceeding the legal limit, which is 0.53g/l in Denmark. The percentage of seriously injured drivers testing positive for medicinal drugs at levels above the Danish legal limit was 6.8%. Benzodiazepines and Z-drugs (6.4%) comprised the majority of this group. One or more illegal drugs (primarily amphetamines and cannabis) were found to be above the Danish legal limit in 4.9% of injured drivers. Young men (median age 31 years) were over-represented among injured drivers who violated Danish law for alcohol and drugs. Diazepam (4.4%), tramadol (3.2%), and clonazepam (3.0%) were the medicinal drugs most frequently detected at levels above LOQ, whereas amphetamines (5.4%) (amphetamine [5.2%] and methamphetamine [1.5%]), tetrahydrocannabinol (3.7%), and cocaine (3.3%), including the metabolite benzoylecgonine, were the most frequently detected illegal drugs. A driver could be positive for more than one substance; therefore, percentages are not mutually exclusive. Poly-drug use was observed in 112 (13%) seriously injured drivers. Tramadol was detected above DRUID cutoffs in 2.1% of seriously injured drivers. This is 3.5 times that observed in a Danish survey of randomly selected drivers. Moreover, illegal and medicinal drug levels above the Danish legal limit were present more than 10 times as frequently as in injured drivers, whereas ethanol was present more than 30 times as frequently than in randomly selected drivers. The results indicate that there is an increased risk in traffic when driving under the influence of psychoactive drugs, especially alcohol in young male drivers. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Quantitative measurement of salivary testosterone in Korean adults by stable isotope-dilution liquid chromatographyelectrospray-tandem mass spectrometry.

PubMed

Lee, Sanghoo; Kwon, Soonho; Shin, Hye-Jin; Park, Jimyeong; Lim, Hwan-Sub; Lee, Kyoung-Ryul; Kim, Young-Jin

2010-11-01

Salivary testosterone levels in Korean adults were quantitatively measured for the first time by liquid chromatography-electrospray-tandem mass spectrometry (LC ESI MS/MS). Salivary testosterone was separated on a multiple reaction monitoring (MRM) chromatogram within 7 min. The LC ESI MS/MS assay was validated over the linearity range of 0.01-2.00 ng/ml (r=0.99987) using testosterone-d(3) as an internal standard. The lower limit of quantification (LOQ) was 0.01 ng/ml. The intra- and inter-assay precisions were 1.54% to 4.09% and 0.96% to 4.29%, respectively. The mean recovery was 93.32% (range 88.43-98.05%). The validated assay was then applied to measure the salivary testosterone levels of Korean adults. In men, the salivary testosterone level collected between 9:00-11:00 am was approximately 2.8 times higher than that in women (P < 0.0001). Salivary testosterone levels in both sexes negatively correlated with age. The present assay would also be useful in measuring salivary testosterone levels in clinical laboratories.

Preliminary investigation on the occurrence of several sulfonamide antibiotics in the Haihe River Basin of China

NASA Astrophysics Data System (ADS)

Zhang, S. L.; Zhang, J.; Wang, Z. G.; Wang, Y. Z.; Liang, S. T.; Liu, C.; Wang, Z.

2017-08-01

Several samples collected from lakes, rivers and reservoirs in Haihe river basin of China were analyzed for 8 sulfonamide antibiotics by using solid-phase extraction and liquid chromatography with tandem mass spectrometry (HPLC-MS/MS). All water samples were enriched with HLB extraction cartridges. The antibiotics were separated by gradient elution with methanol as the mobile phase adding 0.1% formic acid. The eluate was then analyzed by the mode of multiple reaction monitoring (MRM). The limits of detection (LOD) and quantification (LOQ) were 0.4-1.0 ng/L and 1.0-3.0 ng/L respectively. The method was used for the analysis of 13 samples from Haihe river basin in China. The results showed that sulfamethoxazole was present in all water samples with maximum concentration of 107.59 ng/L. Sulfadiazine was also frequently detected, concentrations ranging from 2.81 ng/L to 85.35 ng/L. Other sulfonamide antibiotics were not detected in most water samples, especially for those samples from drinking water resources.

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

PubMed

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

2011-07-01

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

Determination of artificial sweeteners in water samples by solid-phase extraction and liquid chromatography-tandem mass spectrometry.

PubMed

Ordóñez, Edgar Y; Quintana, José Benito; Rodil, Rosario; Cela, Rafael

2012-09-21

The development and performance evaluation of an analytical method for the determination of six artificial sweeteners in environmental waters using solid-phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry are presented. To this end, different SPE alternatives have been evaluated: polymeric reversed-phase (Oasis HLB, Env+, Plexa and Strata X), and mixed-mode with either weak (Oasis WAX) or strong anionic-exchange (Oasis MAX and Plexa PAX) sorbents. Among them, reversed-phase sorbents, particularly Oasis HLB and Strata X, showed the best performance. Oasis HLB provided good trueness (recoveries: 73-112%), precision (RSD<10%) and limits of quantification (LOQ: 0.01-0.5 μg/L). Moreover, two LC separation mechanisms were evaluated: reversed-phase (RPLC) and hydrophilic interaction (HILIC), with RPLC providing better performance than HILIC. The final application of the method showed the presence of acesulfame, cyclamate, saccharin and sucralose in the wastewater and surface water samples analyzed at concentrations up to 54 μg/L. Copyright © 2012 Elsevier B.V. All rights reserved.

A simple, rapid and novel method based on salting-out assisted liquid-liquid extraction for ochratoxin A determination in beer samples prior to ultra-high performance liquid chromatography coupled to tandem mass spectrometry.

PubMed

Mariño-Repizo, Leonardo; Goicoechea, Hector; Raba, Julio; Cerutti, Soledad

2018-06-07

A novel, simple, easy and cheap sample treatment strategy based on salting-out assisted liquid-liquid extraction (SALLE) for ochratoxin A (OTA) ultra-trace analysis in beer samples using ultra-high performance liquid chromatography-tandem mass spectrometry determination was developed. The factors involved in the efficiency of pretreatment were studied employing factorial design in the screening phase and the optimal conditions of the significant variables on the analytical response were evaluated using a central composite face-centred design (CCF). Consequently, the amount of salt ((NH 4 ) 2 SO 4 ), together with the volumes of sample, hydrophilic (acetone) and nonpolar (toluene) solvents, and times of vortexing and centrifugation were optimized. Under optimized conditions, the limits of detection (LOD) and quantification (LOQ) were 0.02 µg l -1 and 0.08 µg l -1 respectively. OTA extraction recovery by SALLE was approximately 90% (0.2 µg l -1 ). Furthermore, the methodology was in agreement with EU Directive requirements and was successfully applied for analysis of beer samples.

Offline Solid-phase Extraction Large-volume Injection-Gas chromatography for the Analysis of Mineral Oil-saturated Hydrocarbons in Commercial Vegetable Oils.

PubMed

Liu, Lingling; Huang, Hua; Wu, Yanwen; Li, Bingning; Ouyang, Jie

2017-09-01

An offline solid-phase extraction (SPE) approach combined with a large-volume injection (LVI)-gas chromatography-flame ionization detector (LVI-GC-FID) is improved for routine analysis of mineral oil saturated hydrocarbons (MOSH) in vegetable oils. The key procedure of the method consists in using offline SPE columns for MOSH purification. The SPE column packed with 1% Ag-activated silica gel was used to separate MOSH from triglycerides and olefins in variety of vegetable oils. The eluent of MOSH fraction was only 3 mL and the concentration step was quick with little evaporation loss. The limit of quantification (LOQ) of the method was 2.5 mg/kg and the linearity ranged from 2 to 300 mg/kg. The accuracy was assessed by measuring the recoveries from spiked oil samples and was higher than 90%. Twenty-seven commercial vegetable oils were analyzed, and different levels of MOSH contamination were detected with the highest being 259.4 mg/kg. The results suggested that it is necessary to routinely detect mineral oil contamination in vegetable oils for food safety.

Validation of QuEChERS based method for determination of fenitrothion residues in tomatoes by gas chromatography-flame photometric detector: Decline pattern and risk assessment.

PubMed

Malhat, Farag; Boulangé, Julien; Abdelraheem, Ehab; Abd Allah, Osama; Abd El-Hamid, Rania; Abd El-Salam, Shokr

2017-08-15

A simple and rapid gas chromatography with flame photometric detector (GC-FPD) determination method was developed to detect residue levels and investigate the dissipation pattern and safe use of fenitrothion in tomatoes. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) using an ethyl acetate-based extraction, followed by a dispersive solid-phase extraction (d-SPE) with primary-secondary amine (PSA) and graphite carbon black (GCB) for clean up, was applied prior to GC-FPD analysis. The method showed satisfactory linearity, recovery and precision. The limits of detection (LOD) and quantification (LOQ) were 0.005 and 0.01mg/kg, respectively. The residue levels of fenitrothion were best described by first order kinetics with a half-life of 2.2days in tomatoes. The potential health risks posed by fenitrothion were not significant, based on supervised residue trial data. The current findings could provide guidance for safe and reasonable use of fenitrothion in tomatoes and prevent health problems to consumers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of a novel method for determination of mercury based on its inhibitory effect on horseradish peroxidase activity followed by monitoring the surface plasmon resonance peak of gold nanoparticles

NASA Astrophysics Data System (ADS)

Khodaveisi, Javad; Shabani, Ali Mohammad Haji; Dadfarnia, Shayessteh; Moghadam, Masoud Rohani; Hormozi-Nezhad, Mohammad Reza

2016-01-01

A highly sensitive and simple indirect spectrophotometric method has been developed for the determination of trace amounts of inorganic mercury (Hg2 +) in aqueous media. The method is based on the inhibitory effect of Hg2 + on the activity of horseradish peroxidase (HRP) in the oxidation of ascorbic acid by hydrogen peroxide followed by the reduction of Au3 + to Au-NPs by unreacted ascorbic acid and the measurement of the absorbance of localized surface plasmon resonance (LSPR) peak of gold nanoparticles (at 530 nm) which is directly proportional to the concentration of Hg2 +. Under the optimum conditions, the calibration curve was linear in the concentration range of 1-220 ng mL- 1. Limits of detection (LOD) and quantification (LOQ) were 0.2 and 0.7 ng mL- 1, respectively and the relative standard deviation at 100 ng mL- 1 level of Hg2 + was 2.6%. The method was successfully applied to the determination of mercury in different water samples.

Validation of a sensitive LC-MS assay for quantification of glyburide and its metabolite 4-transhydroxy glyburide in plasma and urine: an OPRU Network study

PubMed Central

Naraharisetti, Suresh Babu; Kirby, Brian J.; Hebert, Mary F.; Easterling, Thomas R.; Unadkat, Jashvant D.

2009-01-01

Glyburide (glibenclamide, INN), a second generation sulfonylurea is widely used in the treatment of gestational diabetes mellitus (GDM). None of the previously reported analytical methods provide adequate sensitivity for the expected sub-nanogram/mL maternal and umbilical cord plasma concentrations of glyburide during pregnancy. We developed and validated a sensitive and low sample volume liquid chromatographic-mass spectrometric (LC-MS) method for simultaneous determination of glyburide (GLY) and its metabolite, 4-transhydroxy glyburide (M1) in human plasma (0.5 ml) or urine (0.1 ml). The limits of quantitation (LOQ) for GLY and M1 in plasma were 0.25 and 0.40 ng/mL, respectively whereas it was 1.06 ng/mL for M1 in urine. As measured by quality control samples, precision (% coefficient of variation) of the assay was < 15% whereas the accuracy (% deviation from expected) ranged from −10.1–14.3%. We found that the GLY metabolite, M1 is excreted in the urine as the glucuronide-conjugate. PMID:17980680

A simultaneous determination of anti-cancer drugs in hospital effluent by DLLME HPLC-FLD, together with a risk assessment.

PubMed

Souza, Darliana M; Reichert, Jaqueline F; Martins, Ayrton F

2018-06-01

Currently, there is an increasing use of anti-cancer drugs, and hence their occurrence in the environment must be properly managed, in particular, in the light of their high degree of toxicity. In this study, analytical methods using HPLC-FLD assisted by microextraction and solid phase extraction, were developed and validated for the determination of doxorubicin, daunorubicin, epirubicin and irinotecan in hospital effluent. The validation results show determination coefficients (r 2 ) higher than 0.99 and recovery values between 74% and 105%, with an intraday precision of <15%.The limit of quantification was 1.0 μg L - 1 and there were almost no matrix effects. The methods proposed were employed for the determination of the named chemotherapeutics in effluent samples of the University Hospital of Santa Maria, Brazil and quantified in the range of ≥LOQ ̶ 6.22 μg L -1 . A preliminary ecotoxicological risk assessment showed values that were potentially very harmful, and thus, the treatment of the hospital effluents requires special attention. Copyright © 2018 Elsevier Ltd. All rights reserved.

Migration studies of nickel and chromium from ceramic and glass tableware into food simulants.

PubMed

Szynal, Tomasz; Rebeniak, Małgorzata; Mania, Monika

In addition to the release of lead and cadmium from ceramic and glass vessels, (acceptable limits being set by the EU 84/500/EC Directive), other harmful metals can migrate, such as nickel and chromium. Permissible migration limits for these latter metals however have not yet been set in the EU legislation. Both the toxic properties of nickel and chromium and the measures taken by the European Commission Working Group on Food Contact Materials for verifying permissible migration limits for lead, cadmium and other metals from ceramics have acted as drivers for studies on nickel and chromium release from ceramic and glass tableware. To investigate the migration of nickel and chromium into food simulants from ceramic and glassware, available on the Polish market, which are intended for coming into contact with food. Potential consumer exposure can thereby be estimated from the release of these elements into food. Tableware consisted of ceramics and glass vessels generally available on the domestic market, with inner surfaces being mainly coloured and with rim decorations. Migration of nickel and chromium studied from the ceramics was carried out in 4% acetic acid (24 ± 0.5 hrs at 22 ± 2°C), whilst that from glassware in 4% acetic acid (24 ± 0.5 hrs at 22 ± 2°C) and 0.5% citric acid (2 ± 0.1 hrs at 70 ± 2°C). The concentrations of metals which had migrated into the test solutions were measured by using flame atomic absorption spectrometry (FAAS). This analytical procedure had been previously validated by measuring nickel and chromium released into food simulants from ceramic and glass tableware where working ranges, detection limits, quantification limits, repeatability, accuracy, mean recovery and uncertainty were established. Migration of nickel and chromium was measured from 172 ceramic and 52 and glass vessels samples, with all results being below the limits of quantification (LOQ = 0.02 mg/L), excepting one instance where a 0.04 mg/L concentration of nickel was found. The validated methods for measuring chromium achieved the following parameters; 0.02 to 0.80 mg/L operating range, 0.01 mg/L detection limit, 0.02 mg/L limit of quantification, 6% repeatability, 2.8% accuracy, 102% average recovery and 11% uncertainty. For the nickel method the corresponding parameters were 0.02 to 0.80 mg/L work- ing range, 0.02 mg/L limit of quantification, 0.01 mg/L detection limit, 5% repeatability, 6.5% accuracy, 101% average recovery and 12% uncertainty. The tested ceramics and glassware did not pose a threat to human health regarding migration of nickel and chromium, and thus any potential exposure to these metals released from these products into food will be small. However, due to the toxicity of these metals, the migration of nickel and chromium is still required for articles coming into contact with food, which includes metalware. ceramic tableware, ceramics, glassware, food contact articles, nickel, chromium leaching, migration.

A Method for Multiple Mycotoxin Analysis in Wines by Solid Phase Extraction and Multifunctional Cartridge Purification, and Ultra-High-Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry

PubMed Central

Tamura, Masayoshi; Takahashi, Ayumi; Uyama, Atsuo; Mochizuki, Naoki

2012-01-01

An analytical method using two solid phase extractions and ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) was developed for the identification and quantification of 14 mycotoxins (patulin, deoxynivalenol, aflatoxins B1, B2, G1, G2, M1, T-2 toxin, HT-2 toxin, zearalenone, fumonisins B1, B2, B3, and ochratoxin A) in domestic and imported wines. Mycotoxins were purified with an Oasis HLB cartridge, followed by a MultiSepTM #229 Ochra. As a result, sufficient removal of the pigments and highly polar matrices from the red wines was achieved. UHPLC conditions were optimized, and 14 mycotoxins were separated in a total of 13 min. Determinations performed using this method produced high correlation coefficients for the 14 mycotoxins (R > 0.990) and recovery rates ranging from 76 to 105% with good repeatability (relative standard deviation RSD < 12%). Twenty-seven samples of domestic and imported wines were analyzed using this method. Although ochratoxin A (OTA) and fumonisins (FMs) were detected in several samples, the FM levels were less than limits of quantification (LOQs) (1 μg/L), and even the largest of the OTA levels was below the EU regulatory level (2 μg/L). These results suggest that the health risk posed to consumers from the wines available in Japan is relatively low. PMID:22822458

Determination of diethanolamine or N-methyldiethanolamine in high ammonium concentration matrices by capillary electrophoresis with indirect UV detection: application to the analysis of refinery process waters.

PubMed

Bord, N; Crétier, G; Rocca, J-L; Bailly, C; Souchez, J-P

2004-09-01

Alkanolamines such as diethanolamine (DEA) and N-methyldiethanolamine (MDEA) are used in desulfurization processes in crude oil refineries. These compounds may be found in process waters following an accidental contamination. The analysis of alkanolamines in refinery process waters is very difficult due to the high ammonium concentration of the samples. This paper describes a method for the determination of DEA in high ammonium concentration refinery process waters by using capillary electrophoresis (CE) with indirect UV detection. The same method can be used for the determination of MDEA. Best results were achieved with a background electrolyte (BGE) comprising 10 mM histidine adjusted to pH 5.0 with acetic acid. The development of this electrolyte and the analytical performances are discussed. The quantification was performed by using internal standardization, by which triethanolamine (TEA) was used as internal standard. A matrix effect due to the high ammonium content has been highlighted and standard addition was therefore used. The developed method was characterized in terms of repeatability of migration times and corrected peak areas, linearity, and accuracy. Limits of detection (LODs) and quantification (LOQs) obtained were 0.2 and 0.7 ppm, respectively. The CE method was applied to the determination of DEA or MDEA in refinery process waters spiked with known amounts of analytes and it gave excellent results, since uncertainties obtained were 8 and 5%, respectively.

Evaluation of polyethersulfone performance for the microextraction of polar chlorinated herbicides from environmental water samples.

PubMed

Prieto, Ailette; Rodil, Rosario; Quintana, José Benito; Cela, Rafael; Möder, Monika; Rodríguez, Isaac

2014-05-01

In this work, the suitability of bulk polyethersulfone (PES) for sorptive microextraction of eight polar, chlorinated phenoxy acids and dicamba from environmental water samples is assessed and the analytical features of the optimized method are compared to those reported for other microextraction techniques. Under optimized conditions, extractions were performed with samples (18 mL) adjusted at pH 2 and containing a 30% (w/v) of sodium chloride, using a tubular PES sorbent (1 cm length × 0.7 mm o.d., sorbent volume 8 µL). Equilibrium conditions were achieved after 3h of direct sampling, with absolute extraction efficiencies ranging from 39 to 66%, depending on the compound. Analytes were recovered soaking the polymer with 0.1 mL of ethyl acetate, derivatized and determined by gas chromatography-mass spectrometry (GC-MS). Achieved quantification limits (LOQs) varied between 0.005 and 0.073 ng mL(-1). After normalization with the internal surrogate (IS), the efficiency of the extraction was only moderately affected by the particular characteristics of different water samples (surface and sewage water); thus, pseudo-external calibration, using spiked ultrapure water solutions, can be used as quantification technique. The reduced cost of the PES polymer allowed considering it as a disposable sorbent, avoiding variations in the performance of the extraction due to cross-contamination problems and/or surface modification with usage. Copyright © 2014 Elsevier B.V. All rights reserved.

Hydrazinylpyridine based highly selective optical sensor for aqueous source of carbonate ions: Electrochemical and DFT studies

NASA Astrophysics Data System (ADS)

Thimaradka, Vikram; Pangannaya, Srikala; Mohan, Makesh; Trivedi, Darshak R.

2018-03-01

A series of new receptors PDZ1-3 based on 2-(arylidenehydrazinyl)pyridines have been designed and synthesized for the detection of biologically and environmentally important ions. The colorimetric detection of CO32 - using neutral organic receptor PDZ-1 has been achieved with characteristic visual colour change from yellow to green accompanied by a large redshift of 215 nm in absorption maxima. UV-Vis spectroscopic and cyclic voltammetric studies reveal the stoichiometry of binding and electrochemistry of host-guest complex formation. The binding constant was found to be 0.77 × 104 M- 2. In addition, electrochemical studies provide an insight into the stability of the complex. DFT studies performed on the PDZ-1 and PDZ-1 - CO32 - complex reveal the binding mechanism involved in the anion detection process. PDZ-1 is highly selective for carbonate and does not show any colorimetric response towards any other anions or cations, while PDZ-2 and PDZ-3 remain inactive in the ion detection process. The limit of detection (LOD) and limit of quantification (LOQ) of PDZ-1 for carbonate was found to be 0.11 mM and 0.36 mM respectively. Considerable binding constant and limit of detection make PDZ-1 to be used as a real time sensor for the detection of carbonate in environmental and biological samples.

A rapid UPLC method for simultaneous determination of eleven components in 'Ge-Gen-Qin-Lian' decoction.

PubMed

An, Rui; You, Lisha; Zhang, Yizhu; Wang, Xinhong; Ma, Yuemin

2014-10-01

'Ge-Gen-Qin-Lian' Decoction derived from 'Shang-Han-Lun' compiled by Zhang Zhongjing. It is widely used in the treatment of acute gastroenteritis, bacillary dysentery, virus diarrhea. This paper describes a sensitive and specific assay for the determination of the 11-marker compounds using ultra performance liquid chromatography (UPLC). To develop an UPLC method for simultaneous determination of 11 bioactive compounds in 'Ge-Gen-Qin-Lian' preparations. The chromatography analysis was performed on an Agilent Proshell 120 EC-C18 column (4.6 × 50 mm, 2.7 μm) at 30°C with a gradient elution of methanol, 0.5% formic acid and 0.5% ammonium acetate at a flow rate 1.0 ml/min and UV detected at 270 nm. All calibration curves showed good linear regression (r ≥ 0.9993) within tested ranges. Limits of detection (LOD) and limits of quantification (LOQ) fell in the range between 0.0691-1.04 μg/ml and 0.23-3.43 μg/ml, respectively. The mean recovery of each herbal medicine ranged from 96.60 to 102.11%. The method was validated for repeatability, precision, stability, accuracy, and selectivity. The validated method was successfully applied to simultaneous analysis of these active components in 'Ge-Gen-Qin-Lian' decoction.

ET AAS evaluation of the stability and pH-sensitivity of, pH-sensitive stealth liposomes containing cisplatin in mouse plasma.

PubMed

Vieira, F P; Mesquita, T L; Lara, P C P; Ramaldes, G A; Beinner, M A; Silva, J B B; Oliveira, M C; Silveira, J N

2013-10-01

In this work, stability and the pH-sensitivity of pH-sensitive stealth liposomes containing cisplatin exposed to plasma medium and their subsequent responses to pH modifications were evaluated. A method to determine platin in mouse plasma by electrothermal atomic absorption spectroscopy (ET AAS) was developed and validated. At first, a comparative study of sample preparation treatments with basic, acidic, and acidic added with Triton X-100 as a modifier was done. The best treatment was obtained with HCl 3% (v/v). The ET AAS method with acid treatment presented linearity at a range of 10-160 ng Pt/mL. The limits of detection (LOD) was 3.1 ng/mL Pt for acid treatment, while the limit quantification (LOQ) was 10 ng/mL Pt. The acid treatment presented good repeatability (VC<15.0%) and recovery close to 100%. This treatment was chosen for subsequent studies due to its best value of repeatability, recovery, LOD and lowest cost. pH-sensitive stealth liposomes, containing cisplatin, demonstrated low stability and poor response to pH variation after plasma incubation. These findings suggest that further studies are needed to improve liposome formulation i.e., to reduce its size. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparison and characterization of soybean and sunflower lecithins used for chocolate production by high-performance thin-layer chromatography with fluorescence detection and electrospray mass spectrometry.

PubMed

Krüger, Stephanie; Bürmann, Laura; Morlock, Gertrud E

2015-03-25

The scarce availability of nongenetically modified soybeans on the world market represents a growing problem for food manufacturers. Hence, in this study the effects of substituting soybean with sunflower lecithin were investigated with regard to chocolate production. The glycerophospholipid pattern of the different lecithin samples was investigated by high-performance thin-layer chromatography fluorescence detection (HPTLC-FLD) and by HPTLC-positive ion electrospray ionization mass spectrometry (ESI(+)-MS) via the TLC-MS Interface and by scanning HPTLC-matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOFMS). Especially, the contents of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were of interest due to the influencing effects of these two glycerophospholipids on the rheological parameters of chocolate production. The lecithin substitution led to only slight differences in the rheological parameters of milk and dark chocolate. Limits of detection (LODs) and limits of quantification (LOQs) of seven glycerophospholipids were studied for three detection modes. Mean LODs ranged from 8 to 40 mg/kg for HPTLC-FLD and, using a single-quadrupole MS, from 10 to 280 mg/kg for HPTLC-ESI(+)-MS as well as from 15 to 310 mg/kg for HPTLC-FLD-ESI(+)-MS recorded after derivatization with the primuline reagent.

[Simultaneous determination of four alkaloids in Corydalis decumbens (Thunb.) Pers. by high performance liquid chromatography-tandem mass spectrometry].

PubMed

Shen, Yan; Han, Chao; Liu, Cuiping; Zhou, Yongfang; Xia, Biqi; Zhu, Zhenou; Liu, Aili

2011-02-01

A method for the analysis of 4 alkaloids in Corydalis decumbens (Thunb.) Pers. was developed by high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-MS/MS). The sample was extracted in methanol by ultrasonic, filtered and diluted with methanol for further analysis. The analysis was performed on a C18 column (150 mm x 2.1 mm, 3.5 microm) using a gradient elution program with the mobile phase of 0.2% acetic acid solution and acetonitrile. The analyte was determined by an electrospray ionization tandem mass spectrometry in multiple reactions monitoring (MRM) mode. The qualitative and quantitative analyses were based on the retention times and characteristic ion pairs consisting of one parent ion and two fragment ions of the analyte. The limits of detection (LODs) for 4 alkaloids were in the range of 0.02 - 0.2 microg/L, and the limits of quantification (LOQs) were in the range of 0.07 - 0.66 microg/L. The average recoveries were in the range of 93.6% - 103.5% for 4 alkaloids with the relative standard deviations below 3.8%. This method is reliable, sensitive and reproducible, and it can be used for the quality control of Corydalis decumbens (Thunb.) Pers. sample.

Utility of Von Pechman synthesis of coumarin reaction for development of spectrofluorimetric method for quantitation of salmeterol xinafoate in pharmaceutical preparations and human plasma.

PubMed

Awad, Mohamed; Hammad, Mohamed A; Abdel-Megied, Ahmed M; Omar, Mahmoud A

2018-04-30

Simple, precise and selective spectrofluorimetric technique was evolved for quantitation of selective β 2 agonist drug namely salmeterol xinafoate (SAL). Utilizing its phenolic nature, a method was described based on the reaction of the studied drug with ethyl acetoacetate (EAA) to yield extremely fluorescent coumarin product which can be detected at 480 nm (λ ex  = 420 nm). The procedure obeys Beer's law with a correlation coefficient of r = 0.9999 in the concentration range between 500 and 5000 ng ml -1 with and 177 ng ml -1 for limit of detection (LOD) and limit of quantification (LOQ), respectively. Diverse reaction variables influencing the firmness and formation of the coumarin product were accurately examined and modified to ensure greatest sensitivity of the procedure. The proposed technique was performed and examined according to the US Food and Drug Administration (FDA) guidelines for bio-analytical methods and was efficiently applied for quantitation of SAL in both pharmaceutical preparations (% recovery = 100.06 ± 1.07) and spiked human plasma (% recovery = 96.64-97.14 ± 1.01-1.52). Copyright © 2018 John Wiley & Sons, Ltd.

Enhancing the chemiluminescence intensity of a KMnO4 formaldehyde system for estimating the total phenolic content in honey samples using a novel nanodroplet mixing approach in a microfluidics platform.

PubMed

Al Lawati, Haider A J; Al Mughairy, Baqia; Al Lawati, Iman; Suliman, FakhrEldin O

2018-04-30

A novel mixing approach was utilized with a highly sensitive chemiluminescence (CL) method to determine the total phenolic content (TPC) in honey samples using an acidic potassium permanganate-formaldehyde system. The mixing approach was based on exploiting the mixing efficiency of nanodroplets generated in a microfluidic platform. Careful optimization of the instrument setup and various experimental conditions were employed to obtain excellent sensitivity. The mixing efficiency of the droplets was compared with the CL signal intensity obtained using the common serpentine chip design, with both approaches using at a total flow rate of 15 μl min -1 ; the results showed that the nanodroplets provided 600% higher CL signal intensity at this low flow rate. Using the optimum conditions, calibration equations, limits of detection (LOD) and limits of quantification (LOQ) for gallic acid (GA), caffeic acid (CA), kaempferol (KAM), quercetin (QRC) and catechin (CAT) were obtained. The LOD ranged from 6.2 ppb for CA to 11.0 ppb for QRC. Finally, the method was applied for the determination of TPC in several local and commercial honey samples. Copyright © 2018 John Wiley & Sons, Ltd.

Determination of Prometryne in water and soil by HPLC-UV using cloud-point extraction.

PubMed

Zhou, Jihai; Chen, Jiandong; Cheng, Yanhong; Li, Daming; Hu, Feng; Li, Huixin

2009-07-15

A CPE-HPLC (UV) method has been developed for the determination of Prometryne. In this method, non-ionic surfactant Triton X-114 was first used to extract and pre-concentrate Prometryne from water and soil samples. The separation and determination of Prometryne were then carried out in an HPLC-UV system with isocratic elution using a detector set at 254 nm wavelength. The parameters and variables that affected the extraction were also investigated and the optimal conditions were found to be 0.5% of Triton X-114 (w/v), 3% of NaCl (w/v) and heat-assisted at 50 degrees C for 30 min. Using these conditions, the recovery rates of Prometryne ranged from 92.84% to 99.23% in water and 85.48% to 93.67% in soil, respectively, with all the relative standard deviations less than 3.05%. Limit of detection (LOD) and limit of quantification (LOQ) were 3.5 microg L(-1) and 11.0 microg L(-1) in water and 4.0 microg kg(-1) and 13.0 microg kg(-1) in soil, respectively. Thus, we developed a method that has proven to be an efficient, green, rapid and inexpensive approach for extraction and determination of Prometryne from soil samples.

A Survey of Naturally-Occurring Steroid Hormones in Raw Milk and the Associated Health Risks in Tangshan City, Hebei Province, China

PubMed Central

Qu, Xueyin; Su, Chuanyou; Zheng, Nan; Li, Songli; Meng, Lu; Wang, Jiaqi

2017-01-01

In recent years, high levels of hormone residue in food, capable of damaging the health of consumers, have been recorded frequently. In this study, 195 raw milk samples were obtained from Tangshan City, China, and the concentrations of 22 steroid hormones were measured by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Cortisol was detected in 12.5% of raw milk samples (mean 0.61 µg/kg; range:

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

PubMed

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

2016-09-09

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

Application of an enzyme immunoassay for the quantitative determination of azo dye (Orange II) in food products.

PubMed

Xue, Huyin; Xing, Yue; Yin, Yongmei; Zhang, Taichang; Zhang, Bo; Zhang, Yu; Song, Pei; Tian, Xi; Xu, Yinghui; Wang, Peng; Meng, Meng; Xi, Rimo

2012-01-01

This paper reports the preparation of polyclonal antibodies against a synthetic azo dye, Orange II, and the development of an indirect ELISA to detect Orange II in foods. The sulfonic group of Orange II was modified and linked with carrier protein to synthesise an artificial antigen. Based on the checkerboard titration, the method showed excellent sensitivity (IC₅₀ = 0.61 ng g⁻¹) to Orange II in the linear range of 0.05-10 ng g⁻¹. The antibody had little cross-reactivity with Chromotrope FB, Gardenia Yellow, Ponceau 4R, Sunset Yellow and Sudan dyes. The ELISA had limits of detection (LOD) of 0.22, 0.97 and 0.74 ng g⁻¹ in chilli powder, chilli oil and braised pork, respectively. The limits of quantification (LOQ) of the assay were 0.91 ng g⁻¹ in chilli powder, 1.48 ng g⁻¹ in chilli oil and 1.10 ng g⁻¹ in braised pork. For food products fortified with 1-10 ng g⁻¹ Orange II, the inter- and intra-assay variations were all less than 24.0% and 18.0%, respectively. Therefore, the proposed test could be used as a rapid screening method for Orange II detection in food samples.

Microwave assisted solid phase extraction for separation preconcentration sulfamethoxazole in wastewater using tyre based activated carbon as solid phase material prior to spectrophotometric determination

NASA Astrophysics Data System (ADS)

Mogolodi Dimpe, K.; Mpupa, Anele; Nomngongo, Philiswa N.

2018-01-01

This work was chiefly encouraged by the continuous consumption of antibiotics which eventually pose harmful effects on animals and human beings when present in water systems. In this study, the activated carbon (AC) was used as a solid phase material for the removal of sulfamethoxazole (SMX) in wastewater samples. The microwave assisted solid phase extraction (MASPE) as a sample extraction method was employed to better extract SMX in water samples and finally the analysis of SMX was done by the UV-Vis spectrophotometer. The microwave assisted solid phase extraction method was optimized using a two-level fractional factorial design by evaluating parameters such as pH, mass of adsorbent (MA), extraction time (ET), eluent ratio (ER) and microwave power (MP). Under optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.5 μg L- 1 and 1.7 μg L- 1, respectively, and intraday and interday precision expressed in terms of relative standard deviation were > 6%.The maximum adsorption capacity was 138 mg g- 1 for SMX and the adsorbent could be reused eight times. Lastly, the MASPE method was applied for the removal of SMX in wastewater samples collected from a domestic wastewater treatment plant (WWTP) and river water.

Capillary electrophoresis method with UV-detection for analysis of free amino acids concentrations in food.

PubMed

Omar, Mei Musa Ali; Elbashir, Abdalla Ahmed; Schmitz, Oliver J

2017-01-01

Simple and inexpensive capillary electrophoresis with UV-detection method (CE-UV) was optimized and validated for determination of six amino acids namely (alanine, asparagine, glutamine, proline, serine and valine) for Sudanese food. Amino acids in the samples were derivatized with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) prior to CE-UV analysis. Labeling reaction conditions (100mM borate buffer at pH 8.5, labeling reaction time 60min, temperature 70°C and NBD-Cl concentration 40mM) were systematically investigated. The optimal conditions for the separation were 100mM borate buffer at pH 9.7 and detected at 475nm. The method was validated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ), precision (repeatability) (RSD%) and accuracy (recovery). Good linearity was achieved for all amino acids (r(2)>0.9981) in the concentration range of 2.5-40mg/L. The LODs in the range of 0.32-0.56mg/L were obtained. Recoveries of amino acids ranging from 85% to 108%, (n=3) were obtained. The validated method was successfully applied for the determination of amino acids for Sudanese food samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Simultaneous determination of 30 hormones illegally added to anti-ageing functional foods using UPLC-MS/MS coupled with SPE clean-up.

PubMed

He, Xiaoqin; Xi, Cunxian; Tang, Bobin; Wang, Guomin; Chen, Dongdong; Peng, Tao; Mu, Zhaode

2014-01-01

A novel analytical method employing solid-phase extraction (SPE) coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed for the simultaneous determination of 30 hormones in anti-ageing functional foods (capsules, powders and tablets). The analytes were extracted with acetic acid-acetonitrile (1-99 v/v), methanol and acetone, respectively. The extract was purified using a combined column, followed by analyte detection with electrospray ionisation in positive- or negative-ion modes. The results indicated that the 30 compounds had good linear correlations in the range of 1-1000 μg kg⁻¹, and the correlation coefficients were above 0.99. The limits of detection (LOD) and limits of quantification (LOQ) were 0.03-2 and 0.1-5 μg kg⁻¹, respectively. The average recovery of 30 compounds at the three spiked levels varied from 74.7% to 124.1%, and the relative standard deviation (RSD) was 2.4-15.0%. This method was applied to the analysis of hormones in 14 real samples of which seven hormones (such as estrone, dienestrol) were detected in four samples, but the remainder of the hormones were not detected. The developed method is sensitive, efficient, reliable and applicable to real samples.

Determination of personal care products and hormones in leachate and groundwater from Polish MSW landfills by ultrasound-assisted emulsification microextraction and GC-MS.

PubMed

Kapelewska, Justyna; Kotowska, Urszula; Wiśniewska, Katarzyna

2016-01-01

Determination of the endocrine disrupting compounds (EDCs) in leachate and groundwater samples from the landfill sites is very important because of the proven harmful effects of these compounds on human and animal organisms. A method combining ultrasound-assisted emulsification microextraction (USAEME) and gas chromatography-mass spectrometry (GC-MS) was developed for simultaneous determination of seven personal care products (PCPs): methylparaben (MP), ethylparaben (EP), propylparaben (PP), buthylparaben (BP), benzophenone (BPh), 3-(4-methylbenzylidene)camphor (4-MBC), N,N-diethyltoluamide (DEET), and two hormones: estrone (E1) and β-estradiol (E2) in landfill leachate and groundwater samples. The limit of detection (LOD)/limit of quantification (LOQ) values in landfill leachate and groundwater samples were in the range of 0.003-0.083/0.009-0.277 μg L(-1) and 0.001-0.015/0.002-0.049 μg L(-1), respectively. Quantitative recoveries and satisfactory precision were obtained. All studied compounds were found in the landfill leachates from Polish municipal solid waste (MSW) landfills; the concentrations were between 0.66 and 202.42 μg L(-1). The concentration of pollutants in groundwater samples was generally below 0.1 μg L(-1).

An optimized method for neurotransmitters and their metabolites analysis in mouse hypothalamus by high performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry.

PubMed

Yang, Zong-Lin; Li, Hui; Wang, Bing; Liu, Shu-Ying

2016-02-15

Neurotransmitters (NTs) and their metabolites are known to play an essential role in maintaining various physiological functions in nervous system. However, there are many difficulties in the detection of NTs together with their metabolites in biological samples. A new method for NTs and their metabolites detection by high performance liquid chromatography coupled with Q Exactive hybrid quadruple-orbitrap high-resolution accurate mass spectrometry (HPLC-HRMS) was established in this paper. This method was a great development of the applying of Q Exactive MS in the quantitative analysis. This method enabled a rapid quantification of ten compounds within 18min. Good linearity was obtained with a correlation coefficient above 0.99. The concentration range of the limit of detection (LOD) and the limit of quantitation (LOQ) level were 0.0008-0.05nmol/mL and 0.002-25.0nmol/mL respectively. Precisions (relative standard deviation, RSD) of this method were at 0.36-12.70%. Recovery ranges were between 81.83% and 118.04%. Concentrations of these compounds in mouse hypothalamus were detected by Q Exactive LC-MS technology with this method. Copyright © 2016 Elsevier B.V. All rights reserved.

Simple and sensitive monitoring of β2-agonist residues in meat by liquid chromatography-tandem mass spectrometry using a QuEChERS with preconcentration as the sample treatment.

PubMed

Xiong, Lin; Gao, Ya-Qin; Li, Wei-Hong; Yang, Xiao-Lin; Shimo, Shimo Peter

2015-07-01

A liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) method was established for the simultaneous determination of the levels of 10 β2-agonists in meat. The samples were extracted using an aqueous acidic solution and cleaned up using a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) technique utilising a DVB-NVP-SO3Na sorbent synthesised in-house. First, the β2-agonist residues were extracted in an aqueous acidic solution, followed by matrix solid-phase dispersion for clean-up. The linearities of the method were R(2)=0.9925-0.9998, with RSDs of 2.7-15.3% and 73.7-103.5% recoveries. Very low limits of detection (LOD) and quantitation (LOQ) of 0.2-0.9 μg/kg and 0.8-3.2 μg/kg, respectively, were achieved for spiked meat. The values obtained were lower than the maximum residue limits (MRLs) established by the EU and China. These results clearly demonstrate the feasibility of the proposed approach. The evaluated method provided reliable screening, quantification and identification of 10 β2-agonists in meat. Copyright © 2015 Elsevier Ltd. All rights reserved.

Analysis of cocaine and metabolites in hair: validation and application of measurement of hydroxycocaine metabolites as evidence of cocaine ingestion.

PubMed

Schaffer, Michael; Cheng, Chen-Chih; Chao, Oscar; Hill, Virginia; Matsui, Paul

2016-03-01

An LC/MS/MS method to identify and quantitate in hair the minor metabolites of cocaine-meta-, para-, and ortho-hydroxy cocaine-was developed and validated. Analysis was performed on a triple quadrupole ABSciex API 3000 MS equipped with an atmospheric pressure ionization source via an IonSpray (ESI). For LC, a series 200 micro binary pump with a Perkin Elmer Model 200 autosampler was used. The limit of detection (LOD) and limit of quantification (LOQ) were 0.02 ng/10 mg hair, with linearity from 0.02 to 10 ng/10 mg hair. Concentrations of the para isomer in extensively washed hair samples were in the range of 1-2 % of the cocaine in the sample, while the concentrations of the ortho form were considerably less. The method was used to analyze large numbers of samples from two populations: workplace and criminal justice. In vitro experiments to determine if deodorants or peroxide-containing cosmetic treatments could result in the presence of these metabolites in hair showed that this does not occur with extensively washed hair. Presence of hydroxycocaines, when detected after aggressive washing of the hair samples, provides a valuable additional indicator of ingestion of cocaine rather than mere environmental exposure.

HPLC method for determination of SN-38 content and SN-38 entrapment efficiency in a novel liposome-based formulation, LE-SN38.

PubMed

Xuan, Tong; Zhang, J Allen; Ahmad, Imran

2006-05-03

A simple HPLC method was developed for quantification of SN-38, 7-ethyl-10-hydroxycamptothecin, in a novel liposome-based formulation (LE-SN38). The chromatographic separation was achieved on an Agilent Zorbax SB-C18 (4.6 mmx250 mm, 5 microm) analytical column using a mobile phase consisting of a mixture of NaH2PO4 (pH 3.1, 25 mM) and acetonitrile (50:50, v/v). SN-38 was detected at UV wavelength of 265 nm and quantitatively determined using an external calibration method. The limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.05 and 0.25 microg/mL, respectively. The individual spike recovery of SN-38 ranged from 100 to 101%. The percent of relative standard deviation (%R.S.D.) of intra-day and inter-day analyses were less than 1.6%. The method validation results confirmed that the method is specific, linear, accurate, precise, robust and sensitive for its intended use. The current method was successfully applied to the determination of SN-38 content and drug entrapment efficiency in liposome-based formulation, LE-SN38 during early stage formulation development.

Electrochemical DNA biosensor based on poly(2,6-pyridinedicarboxylic acid) modified glassy carbon electrode for the determination of anticancer drug gemcitabine.

PubMed

Tığ, Gözde Aydoğdu; Zeybek, Bülent; Pekyardımcı, Şule

2016-07-01

In this study, a simple methodology was used to develop a new electrochemical DNA biosensor based on poly(2,6-pyridinedicarboxylic acid) (P(PDCA)) modified glassy carbon electrode (GCE). This modified electrode was used to monitor for the electrochemical interaction between the dsDNA and gemcitabine (GEM) for the first time. A decrease in oxidation signals of guanine after the interaction of the dsDNA with the GEM was used as an indicator for the selective determination of the GEM via differential pulse voltammetry (DPV). The guanine oxidation peak currents were linearly proportional to the concentrations of the GEM in the range of 1-30mgL(‒1). Limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.276mgL(‒1) and 0.922mgL(‒1), respectively. The reproducibility, repeatability, and applicability of the analysis to pharmaceutical dosage forms and human serum samples were also examined. In addition to DPV method, UV-vis and viscosity measurements were utilized to propose the interaction mechanism between the GEM and the dsDNA. The novel DNA biosensor could serve for sensitive, accurate and rapid determination of the GEM. Copyright © 2016 Elsevier B.V. All rights reserved.

Development and validation of a single LC-MS/MS assay following SPE for simultaneous hair analysis of amphetamines, opiates, cocaine and metabolites.

PubMed

Imbert, L; Dulaurent, S; Mercerolle, M; Morichon, J; Lachâtre, G; Gaulier, J-M

2014-01-01

The two major challenges in hair analysis are the limited amount of samples usually available and the low targeted concentrations. To overcome these limitations, a liquid chromatography-electrospray-tandem mass spectrometry method (LC-ESI-MS/MS) allowing the simultaneous analysis of 17 amphetamines (amphetamine, BDB, m-CPP, dexfenfluramine, DOB, DOM, ephedrine, MBDB, MDA, MDEA, MDMA, methamphetamine, methylphenidate, 4-MTA, norephedrine, norfenfluramine and PMA), 5 opiates (morphine, codeine, heroin, ethylmorphine, and 6AM), cocaine and 5 metabolites [ecgonine methyl ester (EME), benzoylecgonine (BZE), anhydroecgonine methyl ester (AME), cocaethylene, and norcocaine] has been developed. The validation procedure included linearity, intra-day and inter-day variability and accuracy for 5 days (5 replicates at 3 concentration levels). Proficiency studies were used to check the accuracy of the method. As a result, all amphetamines, opiates and cocaine derivatives were satisfactory identified by 2 MRM transitions in 15 min. Calibration curves were performed by a quadratic 1/X weighted regression. The calibration model fits from 0.05 to 10 ng/mg. The limits of detection (LODs) range between 0.005 and 0.030 ng/mg. Precision has been checked by intra-day and inter-day RSD, and associated relative bias, which were lower than 25% for the limits of quantifications (LOQs) and lower than 20% for the other levels tested. This method was routinely applied to hair samples: two positive results of adult drug addicts are presented. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Simultaneous determination of thirteen different steroid hormones using micro UHPLC-MS/MS with on-line SPE system.

PubMed

Márta, Zoltán; Bobály, Balázs; Fekete, Jenő; Magda, Balázs; Imre, Tímea; Mészáros, Katalin Viola; Bálint, Mária; Szabó, Pál Tamás

2018-02-20

Ultratrace analysis of sample components requires excellent analytical performance in terms of limits of quantitation (LOQ). Micro UHPLC coupled to sensitive tandem mass spectrometry provides state of the art solution for such analytical problems. Using on-line SPE with column switching on a micro UHPLC-MS/MS system allowed to decrease LOQ without any complex sample preparation protocol. The presented method is capable of reaching satisfactory low LOQ values for analysis of thirteen different steroid molecules from human plasma without the most commonly used off-line SPE or compound derivatization. Steroids were determined by using two simple sample preparation methods, based on lower and higher plasma steroid concentrations. In the first method, higher analyte concentrations were directly determined after protein precipitation with methanol. The organic phase obtained from the precipitation was diluted with water and directly injected into the LC-MS system. In the second method, low steroid levels were determined by concentrating the organic phase after steroid extraction. In this case, analytes were extracted with ethyl acetate and reconstituted in 90/10 water/acetonitrile following evaporation to dryness. This step provided much lower LOQs, outperforming previously published values. The method has been validated and subsequently applied to clinical laboratory measurement. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid Quantification of Four Anthocyanins in Red Grape Wine by Hydrophilic Interaction Liquid Chromatography/Triple Quadrupole Linear Ion Trap Mass Spectrometry.

PubMed

Sun, Yongming; Xia, Biqi; Chen, Xiangzhun; Duanmu, Chuansong; Li, Denghao; Han, Chao

2015-01-01

The identification and quantification of four anthocyanins (cyanidin-3-O-glucoside, peonidin-3-O-glucoside, delphinidin-3-O-glucoside, and malvidin-3-O-glucoside) in red grape wine were carried out by hydrophilic interaction liquid chromatography/triple quadrupole linear ion trap MS (HILIC/QTrap-MS/MS). Samples were diluted directly and separated on a Merck ZIC HILIC column with 20 mM ammonium acetate solution-acetonitrile mobile phase. Quantitative data acquisition was carried out in the multiple reaction monitoring mode. Additional identification and confirmation of target compounds were performed using the enhanced product ion mode of the linear ion trap. The LOQs were in the range 0.05-1.0 ng/mL. The average recoveries were in the range 94.6 to 104.5%. The HILIC/QTrap-MS/MS platform offers the best sensitivity and specificity for characterization and quantitative determination of the four anthocyanins in red grape wines and fulfills the quality criteria for routine laboratory application.

Development and validation of modified QuEChERS method coupled with LC-MS/MS for simultaneous determination of cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite in various types of honey and royal jelly.

PubMed

Zheng, Weijia; Park, Jin-A; Abd El-Aty, A M; Kim, Seong-Kwan; Cho, Sang-Hyun; Choi, Jeong-Min; Yi, Hee; Cho, Soo-Min; Ramadan, Amer; Jeong, Ji Hoon; Shim, Jae-Han; Shin, Ho-Chul

2018-01-01

Over the past few decades, honey products have been polluted by different contaminants, such as pesticides, which are widely applied in agriculture. In this work, a modified EN - quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method was developed for the simultaneous quantification of pesticide residues, including cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite 2,4-dimethylaniline (2,4-DMA), in four types of honey (acacia, wild, chestnut, and manuka) and royal jelly. Samples were buffered with 0.2M dibasic sodium phosphate (pH 9), and subsequently, acetonitrile was employed as the extraction solvent. A combination of primary secondary amine (PSA) and C18 sorbents was used for purification prior to liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI + /MS-MS) analysis. The estimated linearity measured at six concentration levels presented good correlation coefficients (R 2 )≥0.99. The recovery, calculated from three different spiking levels, was 62.06-108.79% in honey and 67.58-106.34% in royal jelly, with an RSD<12% for all the tested compounds. The matrix effect was also evaluated, and most of the analytes presented signal enhancement. The limits of quantification (LOQ) ranged between 0.001 and 0.005mg/kg in various samples. These are considerably lower than the maximum residue limits (MRL) set by various regulatory authorities. A total of 43 market (domestic and imported) samples were assayed for method application. Among the tested samples, three samples were tested positive (i.e. detected and quantified) only for cymiazole residues. The residues in the rest of the samples were detected but not quantified. We concluded that the protocol developed in this work is simple and versatile for the routine quantification of cymiazole, 2,4-DMA, fipronil, coumaphos, amitraz, and fluvalinate in various types of honey and royal jelly. Copyright © 2017 Elsevier B.V. All rights reserved.

Application of HPLC to study the kinetics of a branched bi-enzyme system consisting of hypoxanthine-guanine phosphoribosyltransferase and xanthine oxidase--an important biochemical system to evaluate the efficiency of the anticancer drug 6-mercaptopurine in ALL cell line.

PubMed

Kalra, Sukirti; Paul, Manash K; Balaram, Hemalatha; Mukhopadhyay, Anup Kumar

2007-05-01

The thiopurine antimetabolite 6-mercaptopurine (6MP) is an important chemotherapeutic drug in the conventional treatment of childhood acute lymphoblastic leukemia (ALL). 6MP is mainly catabolized by both hypoxanthine-guanine phosphoribosyltransferase (HGPRT) and xanthine oxidase (XOD) to form thioinosinic monophosphate (TIMP) (therapeutically active metabolite) and 6-thiouric acid (6TUA) (inactive metabolite), respectively. The activity of both the enzymes varies among ALL patients governing the active and the inactive metabolite profile within the immature lymphocytes. Therefore, an attempt was made to study the kinetic nature of the branched bi-enzyme system acting on 6MP and to quantitate TIMP and 6TUA formed when the two enzymes are present in equal and variable ratios. The quantification of the branched kinetics using spectrophotometric method presents problem due to the closely apposed lambda(max) of the substrates and products. Hence, employing an HPLC method, the quantification of the products was done with the progress of time. The limit of quantification (LOQ) of substrate was found to be 10nM and for products as 50 nM. The limit of detection (LOD) was found to be 1 nM for the substrate and the products. The method exhibited linearity in the range of 0.01-100 microM for 6MP and 0.05-100 microM for both 6TUA and TIMP. The amount of TIMP formed was higher than that of 6TUA in the bi-enzyme system when both the enzymes were present in equivalent enzymatic ratio. It was further found that enzymatic ratios play an important role in determining the amounts of TIMP and 6TUA. This method was further validated using actively growing T-ALL cell line (Jurkat) to study the branched kinetics, wherein it was observed that treatment of 50 microM 6MP led to the generation of 12 microM TIMP and 0.8 microM 6TUA in 6 h at 37 degrees C.

Illicit Fentanyl-Related Fatalities in Florida: Toxicological Findings.

PubMed

Lee, Dayong; Chronister, Chris W; Broussard, Wilson A; Utley-Bobak, Suzanne R; Schultz, Daniel L; Vega, Russell S; Goldberger, Bruce A

2016-10-01

Fentanyl induces pharmacological effects and abuse liability comparable to other prescription opioids and heroin. A surge in fentanyl-related fatalities has been periodically reported throughout the USA. The University of Florida Forensic Toxicology Laboratory observed a significant increase in fentanyl-related deaths starting in mid-2014. The present report evaluated toxicological findings, demographics of the decedents and circumstances of death in the postmortem cases that were submitted to the laboratory for toxicological analysis from July 2014 to January 2015 and that were tested for fentanyl in biological specimens. The cases originated from 6 of the 24 Florida Medical Examiner Districts, with the majority from District 12 (Desoto, Manatee and Sarasota counties). The specimens were analyzed for fentanyl by gas chromatography-mass spectrometry; the limit of detection (LOD) was 0.62 ng/mL and the limit of quantification (LOQ) was 2.5 ng/mL. During the 7-month period, the laboratory tested 143 postmortem cases for fentanyl and 50% had quantifiable fentanyl in postmortem blood. Fentanyl concentrations ranged from 2.5 to 68 ng/mL (n = 66; median: 9.8 ng/mL); six cases were positive for fentanyl >LOD but

Computational-aided design of molecularly imprinted polymer for selective extraction of methadone from plasma and saliva and determination by gas chromatography.

PubMed

Ahmadi, F; Rezaei, H; Tahvilian, R

2012-12-28

The main objective of this research was computational designing of an imprinted polymer for selective solid phase extraction (SPE) of methadone from plasma and saliva samples analyzed by gas chromatography-flam ionization detector (GC-FID). The density functional theory (DFT) at B3LYP/6-31G+ (d, p) level and Gaussian 2003 package was used to calculate the interaction energy of template-monomers (ΔE). The effect of polymerization solvent was also studied using polarizable continuum model (PCM). It was shown that, methacrylic acid (MAA) gave the largest ΔE in acetonitrile as a polymerization solvent. To examine the validity of this approach, two MIP were synthesized for methadone as template molecule and methacrylic acid as functional monomer in acetonitrile (AN) and methanol (MeOH), respectively. The performance of each polymer was evaluated by using imprinting effect. As it is expected, the best results were obtained for the molecularly imprinted polymer (MIP) which was prepared in AN. For the optimized method, the linearity between responses (peak areas) and concentration of methadone in plasma and saliva samples were found over the range of 3.6-40,000 ng mL(-1) (R(2)=0.997) and 3.0-40,000 ng mL(-1) (R(2)=0.998), respectively. The limit of detection (LOD) and limit of quantification (LOQ) for methadone in plasma were calculated to be 2.45 and 3.6 ng mL(-1), respectively. The LOD and LOQ for methadone in saliva were 2.14 and 3.0 ng mL(-1), respectively. The relative standard deviation (RSD; n=4) for plasma samples containing 10, 100, 500, 1000 ng mL(-1)of methadone were 5.98, 5.78, 5.52, 4.78, 4.74, and the RSD (n=4) for saliva sample containing 5, 20, 100, 1000 ng mL(-1) of methadone were 4.74, 5.1, 5.9, 5.6, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Validation of a gas chromatography-triple quadrupole mass spectrometry method for confirmatory analysis of dioxins and dioxin-like polychlorobiphenyls in feed following new EU Regulation 709/2014.

PubMed

L'Homme, B; Scholl, G; Eppe, G; Focant, J-F

2015-01-09

The European Regulations laying down methods of sampling and analysis for the EU official control of levels of polychlorodibenzo-p-dioxins (PCDDs), polychloro-dibenzofurans (PCDFs), dioxin-like (DL) and non dioxin-like (NDL) PCBs in food and feed have been recently amended by EU Regulation Nos. 589/2014 and 709/2014. A major update is the recognition of gas chromatography (GC) triple quadrupole mass spectrometry (GC-QQQMS/MS) as a confirmatory tool for checking compliance with maximum levels (ML). These revisions have been initiated since this technology now exhibits similar performances to GC (magnetic sector) high resolution mass spectrometry (GC-HRMS). In this paper, we show a fully validated method for PCDD/Fs and DL-PCBs analysis in feed material of plant origin (vegetable oil) using GC-QQQMS/MS following the dedicated EU Regulation 709/2014. We show that individual analytical criteria (selectivity, linearity, quant/qual MRM transitions, accuracy around ML of 1.50ng WHO2005TEQ/kg, within-lab reproducibility, robustness, and background subtraction) meet the strict requirements set by the EU Regulation. We also propose a clear interpretation of instrumental limit of quantitation (iLOQ) as a 'performance-LOQ', defined in a specific way for GC-QQQMS/MS, and method limit of quantitation (mLOQ) as 'real-LOQ' that is used to report bound results. Eventually, the evaluation of measurement uncertainty, following a top-down approach and data produced with our method, demonstrates similar results than with GC-HRMS, thus offering a reliable alternative to the standard method for vegetable oil. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantification of all 209 PCB congeners in blood-Can indicators be used to calculate the total PCB blood load?

PubMed

Kraft, M; Rauchfuss, K; Sievering, S; Wöckner, M; Neugebauer, F; Fromme, H

2017-03-01

Polychlorinated biphenyls (PCBs) are a substance group of 209 theoretically possible compounds. The human body burden of PCBs is commonly calculated based on so-called indicator congeners such as PCB 138, PCB 153 and PCB 180, which are analyzed in human blood. The German "Human Biomonitoring (HBM) Commission" assumes that the sum of these indicator congeners multiplied by a factor of 2 represents the total PCB burden. This norm is based on data obtained from exposure studies after dietary intake. Data from indoor air shows a different congener pattern, which might lead to a relatively higher intake of lower chlorinated PCBs by inhalation. In two independent studies with adult participants from two regions in Germany, we measured all 209 PCB congeners in 44 whole blood and 42 plasma samples. Participants from the whole blood study group had additional exposure to PCBs via indoor air. With our analytical method, 141 individual PCB congeners, 27 coeluted pairs of PCB congeners and 2 records of 3 and 4 coeluted PCBs could be determined. Thus, 172 analysis results were reported per sample. In the whole blood samples, 50 congeners showed values below the limit of quantification (LOQ), whereas 94 congeners could not be detected in any of plasma samples. Total PCB concentrations (Σ 209 PCB congeners, incl. ½ LOQ) in the whole blood samples ranged from 99 to 2152ng PCB/g lipid (Median: 454ng/g lipid; 95th Percentile: 1404ng/g lipid). The sum of all 209 measured PCB (incl. ½ LOQ) in plasma samples showed levels between 52 and 933ng PCB/g lipid (Median: 226ng/g lipid; 95th Percentile: 642ng/g lipid). Our results show that the burden of PCBs on the human body is caused mainly by the three highly chlorinated indicator congeners PCB 138, PCB 153 and PCB 180. In median approximately 50% of the total PCB content in human whole blood or plasma samples can be attributed to these congeners. Total PCB, calculated by multiplying the sum of the three indicator congeners by 2, showed a strong and highly significant correlation to the sum of all 209 measured congeners for each sample. A slightly stronger correlation in the whole blood samples could be achieved by choosing six indicator congeners, including the lower chlorinated congeners (PCB 28, 52 and 101) into the calculation. Although this difference is very small, it must be considered that higher PCB levels in indoor air than those measured in the present study might be associated with a higher burden of indoor-air-related congeners in exposed individuals. For precautionary reasons, it could therefore be recommended that the assessment of individuals exposed to PCB via indoor air should be carried out based on the sum of the 6 indicator congeners PCB 28, PCB 52, PCB 101, PCB 138, PCB 153 and PCB 180 multiplied by a factor of 2. Copyright © 2016 Elsevier GmbH. All rights reserved.

Determination of 3-Monochloropropane-1,2-diol and 2-Monochloropropane-1,3-diol (MCPD) Esters and Glycidyl Esters by Microwave Extraction in Different Foodstuffs.

PubMed

Marc, Corinne; Drouard-Pascarel, Valérie; Rétho, Cécile; Janvion, Patrice; Saltron, Frédéric

2016-06-01

This paper describes a method for the determination of 3-monochloropropane-1,2-diol and 2-monochloropropane-1,3-diol (MCPD) esters and glycidyl esters in various foodstuffs, which are isolated using microwave extraction. The next step is based on alkaline-catalyzed ester cleavage. The released glycidol is transformed into monobromopropanediol (MBPD). All compounds are derivatized in free diols (MCPD and MBPD) with phenylboronic acid and analyzed by gas chromatography-mass spectrometry (GC-MS). The method was validated for oils with a limit of quantitation (LOQ) of 0.1 mg/kg, for chips and crisps with a LOQ of 0.02 mg/kg, and for infant formula with a LOQ of 0.0025 mg/L. Recoveries of each sample were controlled by standard addition on extracts before derivatization. Quantitation was performed by the addition of isotopically labeled glycidyl and 3-monochloropropane-1,2-diol (3-MCPD) esters.

Comparison of human whole blood, plasma, and serum matrices for the determination of perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA), and other fluorochemicals

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

Ehresman, David J.; Froehlich, John W.; Olsen, Geary W.

2007-02-15

Interest in human exposure to perfluorinated acids, including perfluorobutanesulfonate (PFBS), perfluorohexanesulfonate (PFHS), perfluorooctanesulfonate (PFOS), and perfluorooctanoate (PFOA) has led to their measurement in whole blood, plasma and serum. Comparison of measurements in these different blood-based matrices, however, has not been rigorously investigated to allow for across-matrix comparisons. This research evaluated concentrations of PFBS, PFHS, PFOS, and PFOA in whole blood collected in heparin (lithium) and ethylenediamine tetraacetic acid (EDTA), plasma samples collected in heparin and EDTA, and serum (from whole blood allowed to clot). Blood samples were collected from 18 voluntary participants employed at 3M Company. Solid phase extraction methodsmore » were used for all analytical sample preparations, and analyses were completed using high-pressure liquid chromatography/tandem mass spectrometry methods. Serum concentrations ranged from: limit of quantitation (LOQ, 5 ng/mL) to 25 ng/mL for PFBS; LOQ (5 ng/mL) to 75 ng/mL for PFHS; LOQ (5 ng/mL) to 880 ng/mL for PFOS; and LOQ (5 or 10 ng/mL) to 7320 ng/mL for PFOA. Values less than the LOQ were not included in the statistical analyses of the mean of the ratios of individual values for the matrices. PFBS was not quantifiable in most samples. Serum to plasma ratios for PFHS, PFOS, and PFOA were 1:1 and this ratio was independent of the level of concentrations measured. Serum or plasma to whole blood ratios, regardless of the anticoagulant used, approximated 2:1. The difference between plasma and serum and whole blood corresponded to volume displacement by red blood cells, suggesting that the fluorochemicals are not found intracellularly or attached to the red blood cells.« less

Simultaneous separation and determination of fructose, sorbitol, glucose and sucrose in fruits by HPLC-ELSD.

PubMed

Ma, Chunmei; Sun, Zhen; Chen, Changbao; Zhang, Lili; Zhu, Shuhua

2014-02-15

A high-performance liquid chromatography (HPLC) method with evaporative light scattering detection (ELSD) was optimised for simultaneous determination of fructose, sorbitol, glucose and sucrose in fruits. The analysis was carried out on a Phenomenex Luna 5u NH₂ 100A column (250 mm × 4.60mm, 5 micron) with isocratic elution of acetonitrile:water (82.5:17.5, v/v). Drift tube temperature of the ELSD system was set to 82 °C and nitrogen flow rate was 2.0 L min⁻¹. The regression equation revealed good linear relationship (R = 0.9967-0.9989) within test ranges. The limits of detection (LOD) and quantification (LOQ) for four analytes (peach, apple, watermelon, and cherry fruits) were in the range of 0.07-0.27 and 0.22-0.91 mg L⁻¹, respectively. The proposed HPLC-ELSD method was validated for quantification of sugars in peach, apple, watermelon, and cherry fruits, and the results were satisfactory. The results showed that the contents of the four sugars varied among fruits. While fructose (5.79-104.01 mg g⁻¹) and glucose (9.25-99.62 mg g⁻¹) emerged as common sugars in the four fruits, sorbitol (8.70-19.13 mg g⁻¹) were only found in peach, apple and cherry fruits, and sucrose (15.82-106.39 mg g⁻¹) were in peach, apple and watermelon. There was not detectable sorbitol in watermelon and sucrose in cherry fruits, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Identification and quantification of the main isoflavones and other phytochemicals in soy based nutraceutical products by liquid chromatography-orbitrap high resolution mass spectrometry.

PubMed

López-Gutiérrez, Noelia; Romero-González, Roberto; Garrido Frenich, Antonia; Martínez Vidal, José Luis

2014-06-27

The specific phytochemicals composition of soy nutritional supplements is usually not labelled. Hence, 12 dietary supplements were analyzed in order to detect and identify the main phytochemicals present in these samples, using a database containing 60 compounds. Ultra-high performance liquid chromatography coupled to single-stage Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-MS) has been used. Two consecutive extractions, using as extraction solvent a mixture of methanol:water (80:20, v/v), were employed, followed by two dilutions (10 or 100 times depending on the concentration of the components in the sample) with a mixture of an aqueous solution of ammonium acetate 30mM:methanol (50:50, v/v). The method was validated, obtaining adequate recovery and precision values. Limits of detection (LODs) and quantification (LOQs) were calculated, ranging from 2 to 150μgL(-1). Isoflavones were the predominant components present in the analyzed supplements with values higher than 93% of the total amount of phytochemicals in all cases. The aglycones (genistein, daidzein, glycitein and biochanin A) as well as their three conjugated forms, β-glucosides (genistin, daizin and glycitin) were detected and quantified, being daidzein the isoflavone detected at higher concentration in 8 out of 12 samples reported, with values ranging from 684 to 35,970mgkg(-1), whereas biochanin A was detected at very low concentrations, ranging from 18 to 50mgkg(-1). Moreover, other phytochemicals as flavones, flavonols, flavanones and phenolic acids were also detected and quantified. Copyright © 2014 Elsevier B.V. All rights reserved.

Analysis of polar organic contaminants in surface water of the northern Adriatic Sea by solid-phase extraction followed by ultrahigh-pressure liquid chromatography-QTRAP® MS using a hybrid triple-quadrupole linear ion trap instrument.

PubMed

Loos, Robert; Tavazzi, Simona; Paracchini, Bruno; Canuti, Elisabetta; Weissteiner, Christof

2013-07-01

Water-soluble polar organic contaminants are discharged by rivers, cities, and ships into the oceans. Little is known on the fate, pollution effects, and thresholds of toxic chemical mixtures in the marine environment. A new trace analytical method was developed for the multi-compound analysis of polar organic chemical contaminants in marine waters. The method is based on automated solid-phase extraction (SPE) of one-liter water samples followed by ultrahigh-pressure liquid chromatography triple-quadrupole linear ion-trap mass spectrometry (UHPLC-QTRAP(®) MS). Marine water samples from the open Adriatic Sea taken 16 km offshore from Venice (Italy) were analyzed. Method limits of quantification (LOQs) in the low picogram per liter (pg/l) concentration range were achieved. Among the 67 target chemicals analyzed, 45 substances could be detected above the LOQ. The chemicals detected at the highest concentrations were caffeine (up to 367 ng/l), nitrophenol (36 ng/l), 2,4-dinitrophenol (34 ng/l), 5-methyl-1H-benzotriazole (18.5 ng/l), sucralose (11 ng/l), 1H-benzotriazole (9.2 ng/l), terbuthylazine (9 ng/l), alachlor (7.7 ng/l), atrazine-desisopropyl (6.6 ng/l), diethyltoluamide (DEET) (5.0 ng/l), terbuthylazine-desethyl (4.3 ng/l), metolachlor (2.8 ng/l), perfluorooctanoic acid (PFOA) (2.5 ng/l), perfluoropentanoic acid (PFPeA) (2.3 ng/l), linuron (2.3 ng/l), perfluorohexanoic acid (PFHxA) (2.2 ng/l), diuron (2.0 ng/l), perfluorohexane sulfonate (PFHxS) (1.6 ng/l), simazine (1.6 ng/l), atrazine (1.5 ng/l), and perfluorooctane sulfonate (PFOS) (1.3 ng/l). Higher concentrations were detected during summer due to increased levels of tourist activity during this period.

Photo-oxidation products of α-pinene in coarse, fine and ultrafine aerosol: A new high sensitive HPLC-MS/MS method

NASA Astrophysics Data System (ADS)

Feltracco, Matteo; Barbaro, Elena; Contini, Daniele; Zangrando, Roberta; Toscano, Giuseppa; Battistel, Dario; Barbante, Carlo; Gambaro, Andrea

2018-05-01

Oxidation products of α-pinene represent a fraction of organic matter in the environmental aerosol. α-pinene is one of most abundant monoterpenes released in the atmosphere by plants, located typically in boreal, temperate and tropical forests. This primary compound reacts with atmospheric oxidants, such as O3, O2, OH radicals and NOx, through the major tropospheric degradation pathway for many monoterpenes under typical atmospheric condition. Although several studies identified a series of by-products deriving from the α-pinene photo-oxidation in the atmosphere, such as pinic and cis-pinonic acid, the knowledge of the mechanism of this process is partially still lacking. Thus, the investigation of the distribution of these acids in the different size aerosol particles provides additional information on this regard. The aim of this study is twofold. First, we aim to improve the existing analytical methods for the determination of pinic and cis-pinonic acid in aerosol samples, especially in terms of analytical sensitivity and limits of detection (LOD) and quantification (LOQ). We even attempted to increase the knowledge of the α-pinene photo-oxidation processes by analysing, for the first time, the particle-size distribution up to nanoparticle level of pinic and cis-pinonic acid. The analysis of aerosol samples was carried out via high-performance liquid chromatography coupled to a triple quadrupole mass spectrometer. The instrumental LOD values of cis-pinonic and pinic acid are 1.6 and 1.2 ng L-1 while LOQ values are 5.4 and 4.1 ng L-1, respectively. Samples were collected by MOUDI II™ cascade impactor with twelve cut-sizes, from March to May 2016 in the urban area of Mestre-Venice (Italy). The range concentrations in the aerosol samples were from 0.1 to 0.9 ng m-3 for cis-pinonic acid and from 0.1 to 0.8 ng m-3 for pinic acid.

Occurrence of cocaine and metabolites in hospital effluent - A risk evaluation and development of a HPLC method using DLLME.

PubMed

Martins, Ayrton F; Dos Santos, Jeremias B; Todeschini, Bruno H; Saldanha, Loisleini F; da Silva, Daiane S; Reichert, Jaqueline F; Souza, Darliana M

2017-03-01

A fast method for the determination of cocaine and its metabolites in hospital effluent samples was worked out by using liquid chromatography with the aid of fluorescence and diode array detection. Solid phase extraction and dispersive liquid -liquid microextraction were employed during the sample preparation stage. The experiment was conducted by using Chromabond ® C18 ec 6 ml/500 mg cartridges, with recoveries higher than 96.6%, 88.3%, 78.7%, and LOQ m 0.15; 0.18 and 0.30 μg L -1 for cocaine, benzoylecgonine and anhydroecgonine respectively. In the case of DLLME, different chemical conditions and solvent combinations were tested to find the best settings for the microextraction: pH 9; addition of 0.3 mol L -1 NaCl; 150 μL extractor (chloroform) and 350 μL disperser (methanol). The recoveries for cocaine were as high as 98.3% with LOQ m 0.3 μg L -1 . After validation, these methods were applied to quantification of the analytes. While the concentration of the anhydroecgonine, (the main pyrolytic metabolite of cocaine), remained below the limit of detection, the range of concentrations of cocaine and benzoylecgonine determined were 0.4-4.9 μg L -1 and 0.9-8.6 μg L -1 , respectively. The occurrence has a relatively median/high environmental impact. These concentration values suggest that a role is played by other sources of cocaine, probably related to transport, or handling and the consumption of the drug. The outcome is that cocaine can be quantified by using DLLME as well as SPE, however, DLLME offered clear benefits like simplicity, affordability, and speed, as well as only requiring a small volume of solvents and samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oral Fluid and Plasma Cannabinoid Ratios after Around-the-Clock Controlled Oral Δ9-Tetrahydrocannabinol Administration

PubMed Central

Milman, Garry; Schwope, David M.; Schwilke, Eugene W.; Darwin, William D.; Kelly, Deanna L.; Goodwin, Robert S.; Gorelick, David A.; Huestis, Marilyn A.

2013-01-01

BACKGROUND Oral fluid (OF) testing is increasingly important for drug treatment, workplace, and drugged-driving programs. There is interest in predicting plasma or whole-blood concentrations from OF concentrations; however, the relationship between these matrices is incompletely characterized because of few controlled drug-administration studies. METHODS Ten male daily cannabis smokers received around-the-clock escalating 20-mg oral Δ9-tetrahydrocannabinol (THC, dronabinol) doses (40–120 mg/day) for 8 days. Plasma and OF samples were simultaneously collected before, during, and after dosing. OF THC, 11-hydroxy-THC and 11-nor-9-carboxy-THC (THCCOOH) were quantified by GC-MS at 0.5-μg/L, 0.5-μg/L, and 7.5-ng/L limits of quantification (LOQs), respectively. In plasma, the LOQs were 0.25 μg/L for THC and THCCOOH, and 0.5 μg/L for 11-hydroxy-THC. RESULTS Despite multiple oral THC administrations each day and increasing plasma THC concentrations, OF THC concentrations generally decreased over time, reflecting primarily previously self-administered smoked cannabis. The logarithms of the THC concentrations in oral fluid and plasma were not significantly correlated (r = −0.10; P = 0.065). The OF and plasma THCCOOH concentrations, albeit with 1000-fold higher concentrations in plasma, increased throughout dosing. The logarithms of OF and plasma THCCOOH concentrations were significantly correlated (r = 0.63; P < 0.001), although there was high interindividual variation. A high OF/plasma THC ratio and a high OF THC/THCCOOH ratio indicated recent cannabis smoking. CONCLUSIONS OF monitoring does not reliably detect oral dronabinol intake. The time courses of THC and THCCOOH concentrations in plasma and OF were different after repeated oral THC doses, and high inter-individual variation was observed. For these reasons, OF cannabinoid concentrations cannot predict concurrent plasma concentrations. PMID:21875944

Airborne exposure to inhalable hexavalent chromium in welders and other occupations: Estimates from the German MEGA database.

PubMed

Pesch, Beate; Kendzia, Benjamin; Hauptmann, Kristin; Van Gelder, Rainer; Stamm, Roger; Hahn, Jens-Uwe; Zschiesche, Wolfgang; Behrens, Thomas; Weiss, Tobias; Siemiatycki, Jack; Lavoué, Jerome; Jöckel, Karl-Heinz; Brüning, Thomas

2015-07-01

This study aimed to estimate occupational exposure to inhalable hexavalent chromium (Cr(VI)) using the exposure database MEGA. The database has been compiling Cr(VI) concentrations and ancillary data about measurements at German workplaces. We analysed 3659 personal measurements of inhalable Cr(VI) collected between 1994 and 2009. Cr(VI) was determined spectrophotometrically at 540 nm after reaction with diphenylcarbazide. We assigned the measurements to pre-defined at-risk occupations using the information provided about the workplaces. Two-thirds of the measurements were below the limit of quantification (LOQ) and multiply imputed according to the distribution above LOQ. The 75th percentile value was 5.2 μg/m(3) and the 95th percentile was 57.2 μg/m(3). We predicted the geometric mean for 2h sampling in the year 2000, and the time trend of Cr(VI) exposure in these settings with and without adjustment for the duration of measurements. The largest dataset was available for welding (N = 1898), which could be further detailed according to technique. The geometric means were above 5 μg/m(3) in the following situations: spray painting, shielded metal arc welding, and flux-cored arc welding if applied to stainless steel. The geometric means were between 1 μg/m(3) and 5 μg/m(3) for gas metal arc welding of stainless steel, cutting, hard-chromium plating, metal spraying and in the chemical chromium industry. The exposure profiles described here are useful for epidemiologic and industrial health purposes. Exposure to Cr(VI) varies not only between occupations, but also within occupations as shown for welders. In epidemiologic studies, it would be desirable to collect exposure-specific information in addition to the job title. Copyright © 2015 Elsevier GmbH. All rights reserved.

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

PubMed

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

2017-01-01

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

Simultaneous determination of amphetamine-type stimulants and cannabinoids in fingernails by gas chromatography-mass spectrometry.

PubMed

Kim, Jin Young; Cheong, Jae Chul; Kim, Min Kyoung; Lee, Jae Il; In, Moon Kyo

2008-06-01

A gas chromatography-mass spectrometric (GC-MS) method was developed and validated for the simultaneous detection and quantification of four amphetamine-type stimulants (amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA)) and two cannabinoids (Delta9-tetrahydrocannabinol (Delta9-THC) and 11-nor-Delta9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH)) in fingernails. Fingernail clippings (30 mg) were washed with distilled water and methanol, and then incubated in 1.0 M sodium hydroxide at 95 degrees C for 30 min. The compounds of interest were isolated by liquid-liquid extraction followed by derivatization with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) at 70 degrees C for 15 min. The derivatized compounds were analyzed by GC-MS in the selective ion monitoring (SIM) mode. The linear ranges were 0.1-15.0 ng/mg for AP, 0.2-15.0 ng/mg for MDA, Delta9-THC and THCCOOH, and 0.2-30.0 ng/mg for MA and MDMA, with good correlation coefficients (r2 > 0.9991). The intra-day, inter-day, and inter-person precisions were within 10.6%, 6.3%, and 5.3%, respectively. The intra-day, inter-day and inter-person accuracies were between -6.1 and 5.0%, -6.2 and 5.7%, and -6.4 and 5.6%, respectively. The limits of detection (LODs) and quantification (LOQs) for each compound were lower than 0.056 and 0.2 ng/mg, respectively. The recoveries were in the range of 74.0-94.8%. Positive GC-MS results were obtained from specimens of nine suspected MA or cannabis abusers. The concentration ranges of MA, AP, and THCCOOH were 0.10-1.41, 0.12-2.64, and 0.20 ng/mg, respectively. Based on these results, the method proved to be effective for the simultaneous qualification and quantification of amphetamine-type stimulants and cannabinoids in fingernails.

An HS-MRM Assay for the Quantification of Host-cell Proteins in Protein Biopharmaceuticals by Liquid Chromatography Ion Mobility QTOF Mass Spectrometry.

PubMed

Doneanu, Catalin; Fang, Jing; Alelyunas, Yun; Yu, Ying Qing; Wrona, Mark; Chen, Weibin

2018-04-17

The analysis of low-level (1-100 ppm) protein impurities (e.g., host-cell proteins (HCPs)) in protein biotherapeutics is a challenging assay requiring high sensitivity and a wide dynamic range. Mass spectrometry-based quantification assays for proteins typically involve protein digestion followed by the selective reaction monitoring/multiple reaction monitoring (SRM/MRM) quantification of peptides using a low-resolution (Rs ~1,000) tandem quadrupole mass spectrometer. One of the limitations of this approach is the interference phenomenon observed when the peptide of interest has the "same" precursor and fragment mass (in terms of m/z values) as other co-eluting peptides present in the sample (within a 1-Da window). To avoid this phenomenon, we propose an alternative mass spectrometric approach, a high selectivity (HS) MRM assay that combines the ion mobility separation of peptide precursors with the high-resolution (Rs ~30,000) MS detection of peptide fragments. We explored the capabilities of this approach to quantify low-abundance peptide standards spiked in a monoclonal antibody (mAb) digest and demonstrated that it has the sensitivity and dynamic range (at least 3 orders of magnitude) typically achieved in HCP analysis. All six peptide standards were detected at concentrations as low as 0.1 nM (1 femtomole loaded on a 2.1-mm ID chromatographic column) in the presence of a high-abundance peptide background (2 µg of a mAb digest loaded on-column). When considering the MW of rabbit phosphorylase (97.2 kDa), from which the spiked peptides were derived, the LOQ of this assay is lower than 50 ppm. Relative standard deviations (RSD) of peak areas (n = 4 replicates) were less than 15% across the entire concentration range investigated (0.1-100 nM or 1-1,000 ppm) in this study.

Development of one novel multiple-target plasmid for duplex quantitative PCR analysis of roundup ready soybean.

PubMed

Zhang, Haibo; Yang, Litao; Guo, Jinchao; Li, Xiang; Jiang, Lingxi; Zhang, Dabing

2008-07-23

To enforce the labeling regulations of genetically modified organisms (GMOs), the application of reference molecules as calibrators is becoming essential for practical quantification of GMOs. However, the reported reference molecules with tandem marker multiple targets have been proved not suitable for duplex PCR analysis. In this study, we developed one unique plasmid molecule based on one pMD-18T vector with three exogenous target DNA fragments of Roundup Ready soybean GTS 40-3-2 (RRS), that is, CaMV35S, NOS, and RRS event fragments, plus one fragment of soybean endogenous Lectin gene. This Lectin gene fragment was separated from the three exogenous target DNA fragments of RRS by inserting one 2.6 kb DNA fragment with no relatedness to RRS detection targets in this resultant plasmid. Then, we proved that this design allows the quantification of RRS using the three duplex real-time PCR assays targeting CaMV35S, NOS, and RRS events employing this reference molecule as the calibrator. In these duplex PCR assays, the limits of detection (LOD) and quantification (LOQ) were 10 and 50 copies, respectively. For the quantitative analysis of practical RRS samples, the results of accuracy and precision were similar to those of simplex PCR assays, for instance, the quantitative results were at the 1% level, the mean bias of the simplex and duplex PCR were 4.0% and 4.6%, respectively, and the statistic analysis ( t-test) showed that the quantitative data from duplex and simplex PCR had no significant discrepancy for each soybean sample. Obviously, duplex PCR analysis has the advantages of saving the costs of PCR reaction and reducing the experimental errors in simplex PCR testing. The strategy reported in the present study will be helpful for the development of new reference molecules suitable for duplex PCR quantitative assays of GMOs.

Quantification and localization of hesperidin and rutin in Citrus sinensis grafted on C. limonia after Xylella fastidiosa infection by HPLC-UV and MALDI imaging mass spectrometry.

PubMed

Soares, Márcio Santos; da Silva, Danielle Fernandes; Forim, Moacir Rossi; da Silva, Maria Fátima das Graças Fernandes; Fernandes, João Batista; Vieira, Paulo Cezar; Silva, Denise Brentan; Lopes, Norberto Peporine; de Carvalho, Sérgio Alves; de Souza, Alessandra Alves; Machado, Marcos Antônio

2015-07-01

A high performance liquid chromatography-ultraviolet (HPLC-UV) method was developed for quantifying hesperidin and rutin levels in leaves and stems of Citrus limonia, with a good linearity over a range of 1.0-80.0 and 1.0-50.0 μg mL(-1) respectively, with r(2)>0.999 for all curves. The limits of detection (LOD) for both flavonoids were 0.6 and 0.5 μg mL(-1), respectively, with quantification (LOQ) being 2.0 and 1.0 μg mL(-1), respectively. The quantification method was applied to Citrus sinensis grafted onto C. limonia with and without CVC (citrus variegated chlorosis) symptoms after Xylella fastidiosa infection. The total content of rutin was low and practically constant in all analyses in comparison with hesperidin, which showed a significant increase in its amount in symptomatic leaves. Scanning electron microscopy studies on leaves with CVC symptoms showed vessel occlusion by biofilm, and a crystallized material was noted. Considering the difficulty in isolating these crystals for analysis, tissue sections were analyzed by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) to confirm the presence of hesperidin at the site of infection. The images constructed from MS/MS data with a specific diagnostic fragment ion (m/z 483) also showed higher ion intensities for it in infected plants than in healthy ones, mainly in the vessel regions. These data suggest that hesperidin plays a role in the plant-pathogen interaction, probably as a phytoanticipin. This method was also applied to C. sinensis and C. limonia seedlings, and comparison with the graft results showed that the rootstock had an increased hesperidin content ∼3.6 fold greater in the graft stem than in the stem of C. sinensis seedlings. Increase in hesperidin content by rootstock can be related to induced internal defense mechanisms. Copyright © 2015 Elsevier Ltd. All rights reserved.

Ochratoxin A in cocoa and chocolate sampled in Canada.

PubMed

Turcotte, A-M; Scott, P M

2011-06-01

In order to determine the levels of ochratoxin A (OTA) in cocoa and cocoa products available in Canada, a previously published analytical method, with minor modifications to the extraction and immunoaffinity clean-up and inclusion of an evaporation step, was initially used (Method I). To improve the low method recoveries (46-61%), 40% methanol was then included in the aqueous sodium bicarbonate extraction solvent (pH 7.8) (Method II). Clean-up was on an Ochratest™ immunoaffinity column and OTA was determined by liquid chromatography (LC) with fluorescence detection. Recoveries of OTA from spiked cocoa powder (0.5 and 5 ng g(-1)) were 75-84%; while recoveries from chocolate were 93-94%. The optimized method was sensitive (limit of quantification (LOQ) = 0.07-0.08 ng g(-1)), accurate (recovery = 75-94%) and precise (coefficient of variation (CV) < 5%). It is applicable to cocoa and chocolate. Analysis of 32 samples of cocoa powder (16 alkalized and 16 natural) for OTA showed an incidence of 100%, with concentrations ranging from 0.25 to 7.8 ng g(-1); in six samples the OTA level exceeded 2 ng g(-1), the previously considered European Union limit for cocoa. The frequency of detection of OTA in 28 chocolate samples (21 dark or baking chocolate and seven milk chocolate) was also 100% with concentrations ranging from 0.05 to 1.4 ng g(-1); one sample had a level higher than the previously considered European Union limit for chocolate (1 ng g(-1)).

Quantitative determination of insulin entrapment efficiency in triblock copolymeric nanoparticles by high-performance liquid chromatography.

PubMed

Xu, Xiongliang; Fu, Yao; Hu, Haiyan; Duan, Yourong; Zhang, Zhirong

2006-04-11

A rapid and effective isocratic chromatographic procedure was described in this paper for the determination of insulin entrapment efficiency (EE) in triblock copolymeric nanoparticles using reversed-phase high-performance liquid chromatography (RP-HPLC) with an ultraviolet/visible detector at low flow rate. The method has been developed on a Shimadzu Shim-pack VP-ODS column (150 mm x 4.6 mm, 5 microm, Chiyoda-Ku, Tokyo, Japan) using a mixture of 0.2 M sodium sulfate anhydrous solution adjusted to pH 2.3 with phosphoric acid and acetonitrile (73:27, v/v) as mobile phase at the flow rate of 0.8 ml min(-1) and a 214 nm detection. The method was validated in terms of selectivity, linearity, precision, accuracy, solution stability, limit of detection (LOD) and limit of quantification (LOQ). The calibration curve was linear in the concentration range of 2.0-500.0 microg ml(-1), and the limits of detection and quantitation were 8 and 20 ng, respectively. The mean recovery of insulin from spiked samples, in a concentration range of 8-100 microg ml(-1), was 98.96% (R.S.D.= 2.51%, n = 9). The intra- and inter-assay coefficients of variation were less than 2.24%. The proposed method has the advantages of simple pretreatment, rapid isolation, high specificity and precision, which can be used for direct analysis of insulin in commercially available raw materials, formulations of nanoparticles, and drug release as well as stability studies.

Analysis of tetrahydroxylated benzo[a]pyrene isomers in hair as biomarkers of exposure to benzo[a]pyrene.

PubMed

Grova, Nathalie; Hardy, Emilie M; Meyer, Pauline; Appenzeller, Brice M R

2016-03-01

A first gas chromatography-tandem mass spectrometry (GC-MS/MS) method was designed for analysis of four tetrahydroxylated benzo[a]pyrene metabolites (benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydrotetrol, benzo[a]pyrene-r-7,t-8,t-9,t-10-tetrahydrotetrol, benzo[a]pyrene-r-7,t-8,c-9,c-10-tetrahydrotetrol, and benzo[a]pyrene-r-7,t-8,c-9,t-10-tetrahydrotetrol) in hair. Hair powder extract was submitted to liquid-solid extraction, followed by C18 solid-phase purification. The analytes were derivatized with use of N-methyl-N-(trimethylsilyl)trifluoroacetamide and then analyzed by GC-MS/MS in negative chemical ionization mode. The calibration curve was linear from the limit of quantification (LOQ) to 20 pg/mg in hair. The coefficient of determination of the calibration curve was more than 0.975 for all the analytes investigated. The LOQs ranged from 0.075 to 0.2 pg/mg in hair. The method was afterward applied to the analysis of hair of 16 rats randomly allocated to experimental groups receiving 16 polycyclic aromatic hydrocarbons solubilized in oil at 0 or 0.8 mg/kg body weight by oral administration three times per week for 90 days. The analysis of monohydroxylated and dihydroxylated benzo[a]pyrenes was conducted in parallel by GC-MS/MS on the same samples. All tetrahydroxylated benzo[a]pyrene isomers were detected in hair samples collected from rats exposed to polycyclic aromatic hydrocarbons. Benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydrotetrol, the most abundant isomer in hair of treated rats, was also the principal isomer released in DNA adduct hydrolysis in humans. Moreover, the benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydrotetrol concentrations in hair were significantly greater than those of 2-hydroxybenzo[a]pyrene, 1-hydroxybenzo[a]pyrene, 7-hydroxybenzo[a]pyrene, and 4-hydroxybenzo[a]pyrene and similar to those of 9-hydroxybenzo[a]pyrene and 3-hydroxybenzo[a]pyrene. The method was also sufficiently sensitive to monitor environmental levels of exposure because two hair specimens in the eight analyzed from smokers were above the LOQ for benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydrotetrol and benzo[a]pyrene-r-7,t-8,c-9,t-10-tetrahydrotetrol. This study therefore demonstrated that tetrahydroxylated benzo[a]pyrenes in hair might be a useful biomarker for the assessment of both the general population and occupationally exposed workers.

Development and application of absolute quantitative detection by duplex chamber-based digital PCR of genetically modified maize events without pretreatment steps.

PubMed

Zhu, Pengyu; Fu, Wei; Wang, Chenguang; Du, Zhixin; Huang, Kunlun; Zhu, Shuifang; Xu, Wentao

2016-04-15

The possibility of the absolute quantitation of GMO events by digital PCR was recently reported. However, most absolute quantitation methods based on the digital PCR required pretreatment steps. Meanwhile, singleplex detection could not meet the demand of the absolute quantitation of GMO events that is based on the ratio of foreign fragments and reference genes. Thus, to promote the absolute quantitative detection of different GMO events by digital PCR, we developed a quantitative detection method based on duplex digital PCR without pretreatment. Moreover, we tested 7 GMO events in our study to evaluate the fitness of our method. The optimized combination of foreign and reference primers, limit of quantitation (LOQ), limit of detection (LOD) and specificity were validated. The results showed that the LOQ of our method for different GMO events was 0.5%, while the LOD is 0.1%. Additionally, we found that duplex digital PCR could achieve the detection results with lower RSD compared with singleplex digital PCR. In summary, the duplex digital PCR detection system is a simple and stable way to achieve the absolute quantitation of different GMO events. Moreover, the LOQ and LOD indicated that this method is suitable for the daily detection and quantitation of GMO events. Copyright © 2016 Elsevier B.V. All rights reserved.

Hydroxy-fipronil is a new urinary biomarker of exposure to fipronil

PubMed Central

Vasylieva, Natalia; Barnych, Bogdan; Wan, Debin; El-Sheikh, El-Sayed A.; Nguyen, Hai M.; Wulff, Heike; McMahen, Rebecca; Strynar, Mark; Gee, Shirley J.; Hammock, Bruce D.

2017-01-01

Occupational medical surveillance is highly desirable in manufacturing facilities where exposure to chemicals is significant. The insecticide fipronil is generally considered safe for humans but with increasing use, exposure to fipronil is of concern. Identification of urinary metabolites of fipronil may allow development of affordable, cheap and rapid procedures for human exposure evaluation. In this study we developed a fast and easy approach for synthesis of hydroxy-fipronil, a potential urinary metabolite of fipronil. This standard was used to develop a sensitive analytical LC-MS/MS method with a limit of quantification (LOQ) of 0.4 ng/mL. Fipronil sulfone, a known metabolite, and hydroxy-fipronil were quantified in urine samples from rats treated with a fipronil containing diet. Fipronil sulfone concentration centered around 20 ng/mL, while the concentration of hydroxy-fipronil was dose-dependent ranging in 10–10 000 ng/mL and thus being a more sensitive marker of fipronil exposure. A fipronil immunoassay with cross-reactivity to hydroxy-fipronil showed a good correlation in signal intensity with LC-MS data. It was also used to demonstrate the applicability of the method for sample screening in the evaluation of exposure levels. PMID:28343720

Multi-class methodology to determine pesticides and mycotoxins in green tea and royal jelly supplements by liquid chromatography coupled to Orbitrap high resolution mass spectrometry.

PubMed

Martínez-Domínguez, Gerardo; Romero-González, Roberto; Garrido Frenich, Antonia

2016-04-15

A multi-class methodology was developed to determine pesticides and mycotoxins in food supplements. The extraction was performed using acetonitrile acidified with formic acid (1%, v/v). Different clean-up sorbents were tested, and the best results were obtained using C18 and zirconium oxide for green tea and royal jelly, respectively. The compounds were determined using ultra high performance liquid chromatography (UHPLC) coupled to Exactive-Orbitrap high resolution mass spectrometry (HRMS). The recovery rates obtained were between 70% and 120% for most of the compounds studied with a relative standard deviation <25%, at three different concentration levels. The calculated limits of quantification (LOQ) were <10 μg/kg. The method was applied to green tea (10) and royal jelly (8) samples. Nine (eight of green tea and one of royal jelly) samples were found to be positive for pesticides at concentrations ranging from 10.6 (cinosulfuron) to 47.9 μg/kg (paclobutrazol). The aflatoxin B1 (5.4 μg/kg) was also found in one of the green tea samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

Liquid chromatography-tandem mass spectrometry method for the analysis of N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine, a biocidal disinfectant, in dairy products.

PubMed

Slimani, Kahina; Pirotais, Yvette; Maris, Pierre; Abjean, Jean-Pierre; Hurtaud-Pessel, Dominique

2018-10-01

A novel and reliable method to quantify residual levels of N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine in dairy products using ion-pairing reversed-phase liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and fully validated. Sample extraction was done with salting-out technique using acetonitrile and sodium chloride. For LC-MS/MS, the analyte was detected using positive electrospray ionization (ESI+) and two multiple reaction monitoring (MRM) transitions were monitored. The method was validated in the 5-150 µg kg -1 range using total error approach. Thus, performance criteria of the method were evaluated. Relative standard deviations for trueness and precision were lower than 10%; with the exception of hard pressed cheese at 5 µg kg -1 for precision. The limit of quantification (LOQ) was around 5-7 µg kg -1 depending on the matrix of interest. The method was successfully applied to accurately quantify N-(3-aminopropyl)-N-dodecylpropane-1,3-diamine in 146 various dairy products with a maximum contamination level of 225 µg kg -1 in cheese. Copyright © 2018 Elsevier Ltd. All rights reserved.

Quantitative 31P NMR for Simultaneous Trace Analysis of Organophosphorus Pesticides in Aqueous Media Using the Stir Bar Sorptive Extraction Method

NASA Astrophysics Data System (ADS)

Ansari, S.; Talebpour, Z.; Molaabasi, F.; Bijanzadeh, H. R.; Khazaeli, S.

2016-09-01

The analysis of pesticides in water samples is of primary concern for quality control laboratories due to the toxicity of these compounds and their associated public health risk. A novel analytical method based on stir bar sorptive extraction (SBSE), followed by 31P quantitative nuclear magnetic resonance (31P QNMR), has been developed for simultaneously monitoring and determining four organophosphorus pesticides (OPPs) in aqueous media. The effects of factors on the extraction efficiency of OPPs were investigated using a Draper-Lin small composite design. An optimal sample volume of 4.2 mL, extraction time of 96 min, extraction temperature of 42°C, and desorption time of 11 min were obtained. The results showed reasonable linearity ranges for all pesticides with correlation coefficients greater than 0.9920. The limit of quantification (LOQ) ranged from 0.1 to 2.60 mg/L, and the recoveries of spiked river water samples were from 82 to 94% with relative standard deviation (RSD) values less than 4%. The results show that this method is simple, selective, rapid, and can be applied to other sample matrices.

Quantitative analysis of multiple fatty acid ethanolamides using ultra-performance liquid chromatography-tandem mass spectrometry.

PubMed

Lin, Lin; Yang, Haifeng; Jones, Peter J H

2012-12-01

Fatty acid ethanolamides (FAE) represent a group of lipid signaling molecules associated with many physiological and pharmacological actions; however, low FAE tissue levels pose challenges in terms of analytical characterization. The objective was to develop a competent ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for analysis of multiple FAE in animal and human tissue samples. Analytes were extracted using lipid-phase and solid-phase extraction procedures. Chromatographic separation was achieved using a gradient elution in 8 min. FAE were quantified by MS/MS in positive electrospray ionization mode. Linearity was shown in lower and higher FAE concentration ranges, with a limit of quantification (LOQ) ≤0.2 ng/ml for FAE including alpha-linolenoylethanolamide (ALEA), arachidonoylethanolamide (AEA), docosahexaenoylethanolamide (DHEA), linoleoylethanolamide (LEA), oleoylethanolamide (OEA) and palmitoylethanolamide (PEA). Accuracy was shown to be between 92.4% and 108.8%, and precision was <10% for all FAE species. In sum, this sensitive and reproducible method can be used to simultaneously determine multiple FAE at low concentrations in order to facilitate further study of the role of FAE on physiological state. Copyright © 2012 Elsevier Ltd. All rights reserved.

Determination of acetamiprid, imidacloprid, and spirotetramat and their relevant metabolites in pistachio using modified QuEChERS combined with liquid chromatography-tandem mass spectrometry.

PubMed

Faraji, Mohammad; Noorbakhsh, Roya; Shafieyan, Hooshang; Ramezani, Mohammadkazem

2018-02-01

A QuEChERS based methodology was developed for the simultaneous identification and quantification of acetamiprid, imidacloprid, and spirotetramat and their relevant metabolites in pistachio by liquid chromatography-tandem mass spectrometry for the first time. First, sample extraction was done with MeCN:citrate buffer:NaHCO 3 followed by phase separation with the addition of MgSO 4 :NaCl. The supernatant was then cleaned by a primary-secondary amine (PSA), GCB, and MgSO 4 . The proposed method provides a linearity in the range of 5-200µgL -1 , and the linear regression coefficients were higher than 0.99. LOD and LOQ were obtained to be 2 and 5µgkg -1 for the studied insecticides, respectively, with the exception of imidacloprid-olefin (5 and 10µgkg -1 ). Acceptable recoveries (91-110%) were obtained for all the analytes with good intra- and inter-precisions (0.4≥RSD ≤11.0). The method was then used for the pistachio samples collected from a field trial to estimate the maximum residue limits (MRLs) in next step. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multi-class method for determination of veterinary drug residues and other contaminants in infant formula by ultra performance liquid chromatography-tandem mass spectrometry.

PubMed

Zhan, Jia; Zhong, Ying-ying; Yu, Xue-jun; Peng, Jin-feng; Chen, Shubing; Yin, Ju-yi; Zhang, Jia-Jie; Zhu, Yan

2013-06-01

A rapid, simple and generic analytical method which was able to simultaneously determine 220 undesirable chemical residues in infant formula had been developed. The method comprised of extraction with acetonitrile, clean-up by low temperature and water precipitation, and analysis by ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS-MS) using multiple reaction monitoring (MRM) mode. Most fat materials in acetonitrile extract were eliminated by low temperature clean-up. The water precipitation, providing a necessary and supplementary cleanup, could avoid losses of hydrophobic analytes (avermectins, ionophores). Average recoveries for spiked infant formula were in the range from 57% to 147% with associated RSD values between 1% and 28%. For over 80% of the analytes, the recoveries were between 70% and 120% with RSD values in the range of 1-15%. The limits of quantification (LOQs) were from 0.01 to 5 μg/kg, which were usually sufficient to verify the compliance of products with legal tolerances. Application of this method in routine monitoring programs would imply a drastic reduction of both effort and time. Copyright © 2012 Elsevier Ltd. All rights reserved.

Determination of perfluorinated alkylated substances in sediments and sediment core from the Gulf of Gdańsk, Baltic Sea.

PubMed

Falandysz, Jerzy; Rostkowski, Paweł; Jarzyńska, Grażyna; Falandysz, Jaromir J; Taniyasu, Sachi; Yamashita, Nobuyoshi

2012-01-01

Perfluorinated alkylated substances (PFAS) have been determined in surface sediments and sediment core from Gulf of Gdańsk, Baltic Sea. Perfluorooctanesulphonate (PFOS), perfluorohexanesulphonate (PFHxS), perfluorodecanoate (PFDA), perfluoronanoate (PFNA), perfluorooctanoate (PFOA), perfluoroheptanoate (PFHpA), perfluoroundecanote (PFUnDA), perfluorododecanoate (PFDoDA) and perfluorohexanoate (PFHxA) were quantified after isotopic dilution ((13)C(4) PFOS and (13)C(4) PFOA), liquid-liquid extractions by methanol and acetonitrile, cleanup by Envi-Carb, OasisWAX and Envi-Carb and final measurement by HPLC-MS/MS. PFOS, PFHxS, PFUnDA, PFDA, PFNA and PFOA were found in Baltic Sea sediments in concentrations exceeding the method limit of quantification (LOQ) of 2 pg/g. PFOS was detected in concentration up to 0.896 ng/g dry weight and PFHxS up to 0.326 ng/g dw, which shows on a weak pollution. PFOS (48-74%) or PFHxS (45-56%) dominated in PFAS composition of sediments surveyed. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of Environmental Science and Health, Part A to view the free supplemental file.

Accurate determination of residual acrylic acid in superabsorbent polymer of hygiene products by headspace gas chromatography.

PubMed

Zhang, Shu-Xin; Chai, Xin-Sheng; Jiang, Ran

2017-02-17

This work reports on a method for the determination of residual acrylic acid (AA) in the superabsorbent polymers for hygiene products by headspace analysis. It was based on water extraction for the polymer sample at a room temperature for 50min. Then, the AA in the extractant reacted with bicarbonate solution in a closed headspace sample vial, from which the carbon dioxide generated from the reaction (within 20min at 70°C) was detected by gas chromatography (GC). It was found that there is adsorption partition equilibrium of AA between solid-liquid phases. Therefore, an equation for calculating the total AA content in the original polymers sample was derived based on the above phase equilibrium. The results show that the HS-GC method has good precision (RSD<2.51%) and good accuracy (recoveries from 93 to 105%); the limit of quantification (LOQ) was 373mg/kg. The present method is rapid, accurate, and suitable for determining total residual acrylic acid in a wide variety of applications from processing of superabsorbent polymer to commercial products quality control. Copyright © 2017 Elsevier B.V. All rights reserved.

Cloud point extraction and diffuse reflectance-Fourier transform infrared spectroscopic determination of chromium(VI): A probe to adulteration in food stuffs.

PubMed

Tiwari, Swapnil; Deb, Manas Kanti; Sen, Bhupendra K

2017-04-15

A new cloud point extraction (CPE) method for the determination of hexavalent chromium i.e. Cr(VI) in food samples is established with subsequent diffuse reflectance-Fourier transform infrared (DRS-FTIR) analysis. The method demonstrates enrichment of Cr(VI) after its complexation with 1,5-diphenylcarbazide. The reddish-violet complex formed showed λ max at 540nm. Micellar phase separation at cloud point temperature of non-ionic surfactant, Triton X-100 occurred and complex was entrapped in surfactant and analyzed using DRS-FTIR. Under optimized conditions, the limit of detection (LOD) and quantification (LOQ) were 1.22 and 4.02μgmL -1 , respectively. Excellent linearity with correlation coefficient value of 0.94 was found for the concentration range of 1-100μgmL -1 . At 10μgmL -1 the standard deviation for 7 replicate measurements was found to be 0.11μgmL -1 . The method was successfully applied to commercially marketed food stuffs, and good recoveries (81-112%) were obtained by spiking the real samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

A theoretical introduction to "combinatory SYBRGreen qPCR screening", a matrix-based approach for the detection of materials derived from genetically modified plants.

PubMed

Van den Bulcke, Marc; Lievens, Antoon; Barbau-Piednoir, Elodie; MbongoloMbella, Guillaume; Roosens, Nancy; Sneyers, Myriam; Casi, Amaya Leunda

2010-03-01

The detection of genetically modified (GM) materials in food and feed products is a complex multi-step analytical process invoking screening, identification, and often quantification of the genetically modified organisms (GMO) present in a sample. "Combinatory qPCR SYBRGreen screening" (CoSYPS) is a matrix-based approach for determining the presence of GM plant materials in products. The CoSYPS decision-support system (DSS) interprets the analytical results of SYBRGREEN qPCR analysis based on four values: the C(t)- and T(m) values and the LOD and LOQ for each method. A theoretical explanation of the different concepts applied in CoSYPS analysis is given (GMO Universe, "Prime number tracing", matrix/combinatory approach) and documented using the RoundUp Ready soy GTS40-3-2 as an example. By applying a limited set of SYBRGREEN qPCR methods and through application of a newly developed "prime number"-based algorithm, the nature of subsets of corresponding GMO in a sample can be determined. Together, these analyses provide guidance for semi-quantitative estimation of GMO presence in a food and feed product.

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.

The first survey of airborne trace elements at airport using moss bag technique.

PubMed

Vuković, Gordana; Urošević, Mira Aničić; Škrivanj, Sandra; Vergel, Konstantin; Tomašević, Milica; Popović, Aleksandar

2017-06-01

Air traffic represents an important way of social mobility in the world, and many ongoing discussions are related to the impacts that air transportation has on local air quality. In this study, moss Sphagnum girgensohnii was used for the first time in the assessment of trace element content at the international airport. The moss bags were exposed during the summer of 2013 at four sampling sites at the airport 'Nikola Tesla' (Belgrade, Serbia): runway (two), auxiliary runway and parking lot. According to the relative accumulation factor (RAF) and the limit of quantification of the moss bag technique (LOQ T ), the most abundant elements in the samples were Zn, Na, Cr, V, Cu and Fe. A comparison between the element concentrations at the airport and the corresponding values in different land use classes (urban central, suburban, industrial and green zones) across the city of Belgrade did not point out that the air traffic and associated activities significantly contribute to the trace element air pollution. This study emphasised an easy operational and robust (bio)monitoring, using moss bags as a suitable method for assessment of air quality within various microenvironments with restriction in positioning referent instrumental devices.

Pharmaceuticals and consumer products in four wastewater treatment plants in urban and suburb areas of Shanghai.

PubMed

Sui, Qian; Wang, Dan; Zhao, Wentao; Huang, Jun; Yu, Gang; Cao, Xuqi; Qiu, Zhaofu; Lu, Shuguang

2015-04-01

Ten pharmaceuticals and two consumer products were investigated in four wastewater treatment plants (WWTPs) in Shanghai, China. The concentrations of target compounds in the wastewater influents ranged from below the limit of quantification (LOQ) to 9340 ng/L, with the frequency of detection of 31-100%, and the removal efficiencies were observed to be -82 to 100% in the four WWTPs. Concentrations of most target compounds (i.e. diclofenac, caffeine, metoprolol, sulpiride) in the wastewater influents were around three to eight times higher in urban WWTPs than in suburb ones, probably due to the different population served and lifestyles. Mean concentrations of target compounds in the wastewater influent generally decreased by 5-76% after rainfall due to the dilution of raw sewage by rainwater, which infiltrated into the sewer system. In the WWTPs located in the suburb area, the increased flow of wastewater influent led to a shortened hydraulic retention time (HRT) and decreased removal efficiencies of some compounds. On the contrary, the influence of rainfall was not significant on the removal efficiencies of investigated compounds in urban WWTPs, probably due to the almost unchanged influent flow, good removal performance, or bypass system employed.

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

PubMed

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

2009-03-11

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

A highly sensitive solid substrate room temperature phosphorimetry for carbaryl detection based on its activating effect on NaIO4 oxidizing fluorescein.

PubMed

Liu, Jiaming; Huang, Qitong; Liu, Zhen-bo; Lin, Xiaofeng; Zhang, Li-Hong; Lin, Chang-Qing; Zheng, Zhi-Yong

2014-11-01

Fluorescein (HFin) could emit strong and stable room temperature phosphorescence (RTP) signal on polyamide membrane (PAM) using Pb(2+) as the ion perturber. Carbaryl could activate effect on NaIO4 oxidating HFin, which caused the RTP signal of the system to quench sharply. The phosphorescence intensity (ΔI p) of activating system higher 3.3 times (119.4/36.0) than that of non-activating system, and is directly proportional to the content of carbaryl. Thus, an activating solid substrate room temperature phosphorimetry (SSRTP) for carbaryl detection has been established. This sensitive (the limit of quantification (LOQ) was 2.0 × 10(-13) g mL(-1)), selective, simple and rapid method has been applied to determine trace carbaryl in water samples with the results consisting with those obtained by fluorimetry, showing its high accuracy. The apparent activation energy (E) and rate constant (k) of this activating reaction were 20.77 kJ mol(-1) and 1.85 × 10(-4) s(-1), respectively. Meanwhile, the mechanism of activating SSRTP for carbaryl detection was also discussed using infrared spectra (IR).

A new method for determination of cocamidopropyl betaine synthesized from coconut oil through spectral shift of Eriochrome Black T

NASA Astrophysics Data System (ADS)

Gholami, Ali; Golestaneh, Mahshid; Andalib, Zeinab

2018-03-01

Cocamidopropyl betaine (CAPB) is a zwitterionic surfactant that is synthesized using coconut oil and usually supplied in form of an aqueous solution with 25-37% w/w. In this study, a novel method based on UV-visible spectroscopy is developed for an accurate determination of CAPB synthesized from coconut oil. Eriochrome Black T (EBT) as a specific color indicator was added to CAPB and a red shift and color change were observed. This shift leads in increasing wavelength selectivity of the method. The change in the color intensity depends on the concentration of CAPB. By measuring the absorbance of a solution containing CAPB, its concentration was measured. After optimizing all the effective parameters, CAPB was detected in commercial real samples. Using the proposed approach, limit of quantification (LOQ) and relative standard deviation (RSD) were obtained about 4.30 × 10- 5 M and 4.8% respectively. None of unreacted materials or by-products, which were produced in the synthesis of CAPB, showed any interference in the determination of CAPB. This shows that the proposed method is specific and accurate, and can potentially be used for quantitative determination of CAPB in commercial samples with satisfactory results.

Development of a novel method for determination of mercury based on its inhibitory effect on horseradish peroxidase activity followed by monitoring the surface plasmon resonance peak of gold nanoparticles.

PubMed

Khodaveisi, Javad; Shabani, Ali Mohammad Haji; Dadfarnia, Shayessteh; Moghadam, Masoud Rohani; Hormozi-Nezhad, Mohammad Reza

2016-01-15

A highly sensitive and simple indirect spectrophotometric method has been developed for the determination of trace amounts of inorganic mercury (Hg(2+)) in aqueous media. The method is based on the inhibitory effect of Hg(2+) on the activity of horseradish peroxidase (HRP) in the oxidation of ascorbic acid by hydrogen peroxide followed by the reduction of Au(3+) to Au-NPs by unreacted ascorbic acid and the measurement of the absorbance of localized surface plasmon resonance (LSPR) peak of gold nanoparticles (at 530 nm) which is directly proportional to the concentration of Hg(2+). Under the optimum conditions, the calibration curve was linear in the concentration range of 1-220 ng mL(-1). Limits of detection (LOD) and quantification (LOQ) were 0.2 and 0.7 ng mL(-1), respectively and the relative standard deviation at 100 ng mL(-1) level of Hg(2+) was 2.6%. The method was successfully applied to the determination of mercury in different water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

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

Bisphenol A and Bisphenol S release in milk under household conditions from baby bottles marketed in Italy.

PubMed

Russo, Giacomo; Barbato, Francesco; Cardone, Eleonora; Fattore, Margherita; Albrizio, Stefania; Grumetto, Lucia

2018-02-01

A simple and sensitive validated analytical method based on liquid chromatography coupled to tandem fluorescence (FD) and ultraviolet (UV) spectrophotometry was applied to monitor the presence of bisphenol A and bisphenol S in plastic baby bottles marketed in Italy. The limits of detection (LOD) were 3.75 ng mL -1 and 80.00 ng mL -1 , and those of quantification (LOQ) were 12.51 ng mL -1 and 260.00 ng mL -1 for BPA (FD detection) and for BPS (UV detection), respectively. BPA was found in only four samples, two samples undergone to microwave heating and two samples undergone to bottle warmer heating either at 40°C or at 80°C. Although the quantities of leached BPA were well below the reference dose for daily intake established by the European Food Safety Authority (EFSA) (4.0 µg kg -1 bw/day), the release of BPA and BPS from these plastic materials should be carefully considered by the government authorities to increase people's awareness on this issue and to protect the most vulnerable population group.

Ultra-high-pressure liquid chromatography-tandem mass spectrometry method for the determination of alkylphenols in soil.

PubMed

Wang, Jing; Pan, Hefang; Liu, Zhengzheng; Ge, Fei

2009-03-20

A novel method has been developed for the determination of alkylphenols in soil by ultra-high-pressure liquid chromatography employing small particle sizes, combined with tandem mass spectrometry. Soil samples were extracted with pressurized liquid extraction (PLE) and then cleaned with solid-phase extraction (SPE). The extracts were separated on C18 column (1.7 microm, 50 mm x 2.1mm) with a gradient elution and a mobile phase consisting of water and acetonitrile, and then detected by an electrospray ionization tandem mass spectrometry in negative ion mode with multiple reaction monitoring (MRM). Compared with traditional liquid chromatography, it took ultra-high-pressure liquid chromatography much less time to analyze alkylphenols. Additionally, the ultra-high-pressure liquid chromatography/tandem mass spectrometry method produces satisfactory reliability, sensitivity, and accuracy. The average recoveries of the three target analytes were 74.0-103.4%, with the RSD<15%. The calibration curves for alkylphenols were linear within the range of 0.01-0.4 microg/ml, with the correlation coefficients greater than 0.99. When 10 g soil sample was used for analysis, the limits of quantification (LOQs) of the three alkylphenols were all 1.0 microg/kg.

Simultaneous gas chromatographic determination of chlorpyrifos and its impurity sulfotep in liquid pesticide formulations.

PubMed

Płonka, Marlena; Walorczyk, Stanisław; Miszczyk, Marek; Kronenbach-Dylong, Dorota

2016-11-01

An analytical method for simultaneous determination of the active substance (chlorpyrifos) and its relevant impurity (sulfotep) in commercial pesticide formulations has been developed and validated. The proposed method entails extraction of the analytes from samples by sonication with acetone and analysis by gas chromatography-flame ionization detection (GC-FID). The proposed method was characterized by satisfactory accuracy and precision. The repeatability expressed as relative standard deviation (RSD) was lower than the acceptable values calculated from the modified Horwitz equation whereas individual recoveries were in the range of 98-102% and 80-120% for chlorpyrifos and sulfotep, respectively. The limit of quantification (LOQ) for the impurity (sulfotep) was 0.003 mg mL(-1) corresponding to the maximum permitted level according to Food and Agricultural Organization of the United Nations (FAO) specifications for the active substance (chlorpyrifos) being 3 g kg(-1) of the chlorpyrifos content found. The main advantage of the proposed method was a considerable reduction in the analysis time since both analytes were determined based on a single injection into the GC-FID. Analysis of real samples of commercial pesticide formulations confirmed fitness-for-purpose of the proposed method.

Polyamide as an efficient sorbent for simultaneous interface-free determination of three Sudan dyes in saffron and urine using high-performance liquid chromatography-ultra violet detection.

PubMed

Saeidi, Iman; Barfi, Behruz; Payrovi, Moazameh; Feizy, Javid; Sheibani, Hojat A; Miri, Mina; Ghollasi Moud, Farahnaz

2015-01-01

With polyamide (PA) as an efficient sorbent for solid phase extraction (SPE) of Sudan dyes II, III and Red 7B from saffron and urine, their determination by HPLC was performed. The optimum conditions for SPE were achieved using 7 mL methanol/water (1:9, v/v, pH 7) as the washing solvent and 3 mL tetrahydrofuran for elution. Good clean-up and high (above 90%) recoveries were observed for all the analytes. The optimized mobile phase composition for HPLC analysis of these compounds was methanol-water (70:30, v/v). The SPE parameters, such as the maximum loading capacity and breakthrough volume, were also determined for each analyte. The limits of detection (LODs), limits of quantification (LOQs), linear ranges and recoveries for the analytes were 4.6-6.6 microg/L, 13.0-19.8 microg/L, 13.0-5000 microg/L (r2>0.99) and 92.5%-113.4%, respectively. The precisions (RSDs) of the overall analytical procedure, estimated by five replicate measurements for Sudan II, III and Red 7B in saffron and urine samples were 2.3%, 1.8% and 3.6%, respectively. The developed method is simple and successful in the application to the determination of Sudan dyes in saffron and urine samples with HPLC coupled with UV detection.

Separation, concentration and determination of trace chloramphenicol in shrimp from different waters by using polyoxyethylene lauryl ether-salt aqueous two-phase system coupled with high-performance liquid chromatography.

PubMed

Lu, Yang; Yao, Hui; Li, Chuang; Han, Juan; Tan, Zhenjiang; Yan, Yongsheng

2016-02-01

Polyoxyethylene lauryl ether (POELE10)-NaH2PO4 aqueous two-phase extraction system (ATPES) is coupled with HPLC to analyze chloramphenicol (CAP) in aquatic product. Response surface methodology (RSM) was adopted in the multi-factor experiment to determine the optimized conditions. The extraction efficiency of CAP (E%) is up to 99.42% under the optimal conditions, namely, the concentration of NaH2PO4, the concentration of POELE10, pH and temperature were 0.186 g · mL(-1), 0.033 g · mL(-1), 3.8 and 25 °C respectively. The optimal value of enrichment factor of CAP (F) was 22.56 when the concentration of NaH2PO4 was 0.192 g · mL(-1), the concentration of POELE10 was 0.024 g/ml, pH was 4.2 and temperature was 30 °C. The limit of detection (LOD) and limit of quantification (LOQ) of this method are 0.8 μg · kg(-1) and 1 μg · kg(-1), which meet the needs of determining trace or ultratrace CAP in food. The E% and F of this technique are much better than other extraction methods. Copyright © 2015 Elsevier Ltd. All rights reserved.

An isotope dilution capillary electrophoresis/tandem mass spectrometry (CE-MS/MS) method for the simultaneous measurement of choline, betaine, and dimethylglycine concentrations in human plasma.

PubMed

Forteschi, Mauro; Zinellu, Angelo; Assaretti, Stefano; Mangoni, Arduino A; Pintus, Gianfranco; Carru, Ciriaco; Sotgia, Salvatore

2016-10-01

Plasma concentrations of choline, betaine, and dimethylglycine provide valuable information on the flow of methyl groups in key biological processes, particularly during folate deficiency states. We developed a new method to simultaneously measure these analytes in human plasma. Following sample deproteinization using acetonitrile, an aliquot was evaporated to dryness under vacuum to be then taken up by water. Finally, analytes were separated by capillary electrophoresis and detected by electrospray ionization triple-quadrupole mass spectrometry, in multiple reaction monitoring mode, using two stable isotope-labeled internal standards. Linearity of the calibration curves of each analyte was good (R(2) > 0.99). Average limits of detection (LODs) and limits of quantification (LOQs) for choline, betaine, and dimethylglycine were, respectively, 0.43, 0.62, and 0.31 μmol/L and 1.52, 2.11, and 0.97 μmol/L. Mean recovery of three replicates of two spiked concentrations levels was close to 100 % for all of the analytes. Repeatability and intermediate precision, expressed as %RSD of measurements, were <9 %. The method, applied to measure analytes in samples from 30 patients with chronic kidney disease and 30 age- and sex-matched healthy controls, was able to detect differences between groups and the sexes.

Synthesis and characterization of cellulose and hydroxyapatite-carbon electrode composite for trace plumbum ions detection and its validation in blood serum.

PubMed

Ajab, Huma; Dennis, John Ojur; Abdullah, Mohd Azmuddin

2018-07-01

A novel synthesis and characterization of cellulose, hydroxyapatite and chemically-modified carbon electrode (Cellulose-HAp-CME) composite was reported for the analysis of trace Pb(II) ions detection and its validation in blood serum. The Field Emission Scanning Electron Microscopy (FESEM) analyses showed that the composite retained the orderly porous structure but with scattered particle size agglomeration. The Fourier Transform Infrared Spectroscopy (FTIR) spectra suggested the presence of functional groups associated with the bending and stretching of carbon bonds and intermolecular H-bonding. X-ray Diffraction (XRD) analyses further elucidated that the crystallite size could have influenced the properties of the electrode. Based on Thermo-gravimetric Analysis (TGA/DTG), the composites showed thermal stability with more than 60% residual content at 700°C. The sensor was successfully developed for trace Pb(II) ions detection in complex medium such as blood serum, in the physiologically relevant range of 10-60ppb, with resulting Limit of Detection (LOD) of 0.11±0.36ppb and Limit of Quantification (LOQ) of 0.36±0.36ppb. The newly fabricated electrode could be advantageous as a sensing platform with favourable electrochemical characteristics for robust, in situ and rapid environmental and clinical analyses of heavy metal ions. Copyright © 2018 Elsevier B.V. All rights reserved.

A simple and low cost dual-wavelength β-correction spectrophotometric determination and speciation of mercury(II) in water using chromogenic reagent 4-(2-thiazolylazo) resorcinol

NASA Astrophysics Data System (ADS)

Al-Bagawi, A. H.; Ahmad, W.; Saigl, Z. M.; Alwael, H.; Al-Harbi, E. A.; El-Shahawi, M. S.

2017-12-01

The most common problems in spectrophotometric determination of various complex species originate from the background spectral interference. Thus, the present study aimed to overcome the spectral matrix interference for the precise analysis and speciation of mercury(II) in water by dual-wavelength β-correction spectrophotometry using 4-(2-thiazolylazo) resorcinol (TAR) as chromogenic reagent. The principle was based on measuring the correct absorbance for the formed complex of mercury(II) ions with TAR reagent at 547 nm (lambda max). Under optimized conditions, a linear dynamic range of 0.1-2.0 μg mL- 1 with correlation coefficient (R2) of 0.997 were obtained with lower limits of detection (LOD) of 0.024 μg mL- 1 and limit of quantification (LOQ) of 0.081 μg mL- 1. The values of RSD and relative error (RE) obtained for β-correction method and single wavelength spectrophotometry were 1.3, 1.32% and 4.7, 5.9%, respectively. The method was validated in tap and sea water in terms of the data obtained from inductively coupled plasma-optical emission spectrometry (ICP-OES) using student's t and F tests. The developed methodology satisfactorily overcomes the spectral interference in trace determination and speciation of mercury(II) ions in water.

A simultaneous screening and quantitative method for the multiresidue analysis of pesticides in spices using ultra-high performance liquid chromatography-high resolution (Orbitrap) mass spectrometry.

PubMed

Goon, Arnab; Khan, Zareen; Oulkar, Dasharath; Shinde, Raviraj; Gaikwad, Suresh; Banerjee, Kaushik

2018-01-12

A novel screening and quantitation method is reported for non-target multiresidue analysis of pesticides using ultra-HPLC-quadrupole-Orbitrap mass spectrometry in spice matrices, including black pepper, cardamom, chili, coriander, cumin, and turmeric. The method involved sequential full-scan (resolution = 70,000), and variable data independent acquisition (vDIA) with nine consecutive fragmentation events (resolution = 17,500). Samples were extracted by the QuEChERS method. The introduction of an SPE-based clean-up step through hydrophilic-lipophilic-balance (HLB) cartridges proved advantageous in minimizing the false negatives. For coriander, cumin, chili, and cardamom, the screening detection limit was largely at 2 ng/g, while it was 5 ng/g for black pepper, and turmeric. When the method was quantitatively validated for 199 pesticides, the limit of quantification (LOQ) was mostly at 10 ng/g (excluding black pepper, and turmeric with LOQ = 20 ng/g) with recoveries within 70-120%, and precision-RSDs <20%. Furthermore, the method allowed the identification of suspected non-target analytes through retrospective search of the accurate mass of the compound-specific precursor and product ions. Compared to LC-MS/MS, the quantitative performance of this Orbitrap-MS method had agreements in residue values between 78-100%. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct synthesis of nitrogen-doped graphene on platinum wire as a new fiber coating method for the solid-phase microextraction of BXes in water samples: Comparison of headspace and cold-fiber headspace modes.

PubMed

Memarian, Elham; Hosseiny Davarani, Saied Saeed; Nojavan, Saeed; Movahed, Siyavash Kazemi

2016-09-07

In this work, a new solid-phase microextraction fiber was prepared based on nitrogen-doped graphene (N-doped G). Moreover, a new strategy was proposed to solve problems dealt in direct coating of N-doped G. For this purpose, first, Graphene oxide (GO) was coated on Pt wire by electrophoretic deposition method. Then, chemical reduction of coated GO to N-doped G was accomplished by hydrazine and NH3. The prepared fiber showed good mechanical and thermal stabilities. The obtained fiber was used in two different modes (conventional headspace solid-phase microextraction and cold-fiber headspace solid-phase microextraction (CF-HS-SPME)). Both modes were optimized and applied for the extraction of benzene and xylenes from different aqueous samples. All effective parameters including extraction time, salt content, stirring rate, and desorption time were optimized. The optimized CF-HS-SPME combined with GC-FID showed good limit of detections (LODs) (0.3-2.3 μg/L), limit of quantifications (LOQs) (1.0-7.0 μg/L) and linear ranges (1.0-5000 μg/L). The developed method was applied for the analysis of benzene and xylenes in rainwater and some wastewater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Validated spectrofluorimetric method for determination of two phosphodiesterase inhibitors tadalafil and vardenafil in pharmaceutical preparations and spiked human plasma.

PubMed

Abu El-Enin, Mohammed Abu Bakr; Al-Ghaffar Hammouda, Mohammed El-Sayed Abd; El-Sherbiny, Dina Tawfik; El-Wasseef, Dalia Rashad; El-Ashry, Saadia Mahmoud

2016-02-01

A valid, sensitive and rapid spectrofluorimetric method has been developed and validated for determination of both tadalafil (TAD) and vardenafil (VAR) either in their pure form, in their tablet dosage forms or spiked in human plasma. This method is based on measurement of the native fluorescence of both drugs in acetonitrile at λem 330 and 470 nm after excitation at 280 and 275 nm for tadalafil and vardenafil, respectively. Linear relationships were obtained over the concentration range 4-40 and 10-250 ng/mL with a minimum detection of 1 and 3 ng/mL for tadalafil and vardenafil, respectively. Various experimental parameters affecting the fluorescence intensity were carefully studied and optimized. The developed method was applied successfully for the determination of tadalafil and vardenafil in bulk drugs and tablet dosage forms. Moreover, the high sensitivity of the proposed method permitted their determination in spiked human plasma. The developed method was validated in terms of specificity, linearity, lower limit of quantification (LOQ), lower limit of detection (LOD), precision and accuracy. The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from the comparison methods, as revealed by statistical analysis of the obtained results using Student's t-test and the variance ratio F-test. Copyright © 2015 John Wiley & Sons, Ltd.

Simultaneous derivatisation and preconcentration of parabens in food and other matrices by isobutyl chloroformate and dispersive liquid-liquid microextraction followed by gas chromatographic analysis.

PubMed

Jain, Rajeev; Mudiam, Mohana Krishna Reddy; Chauhan, Abhishek; Ch, Ratnasekhar; Murthy, R C; Khan, Haider A

2013-11-01

A simple, rapid and economical method has been proposed for the quantitative determination of parabens (methyl, ethyl, propyl and butyl paraben) in different samples (food, cosmetics and water) based on isobutyl chloroformate (IBCF) derivatisation and preconcentration using dispersive liquid-liquid microextraction in single step. Under optimum conditions, solid samples were extracted with ethanol (disperser solvent) and 200 μL of this extract along with 50 μL of chloroform (extraction solvent) and 10 μL of IBCF was rapidly injected into 2 mL of ultra-pure water containing 150 μL of pyridine to induce formation of a cloudy state. After centrifugation, 1 μL of the sedimented phase was analysed using gas chromatograph-flame ionisation detector (GC-FID) and the peaks were confirmed using gas chromatograph-positive chemical ionisation-mass spectrometer (GC-PCI-MS). Method was found to be linear over the range of 0.1-10 μg mL(-1) with square of correlation coefficient (R(2)) in the range of 0.9913-0.9992. Limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.029-0.102 μg mL(-1) and 0.095-0.336 μg mL(-1) with a signal to noise ratio of 3:1 and 10:1, respectively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Enhanced spectrophotometric detection of Hg in water samples by surface plasmon resonance of Au nanoparticles after preconcentration with vortex-assisted liquid-liquid microextraction

NASA Astrophysics Data System (ADS)

Martinis, Estefanía M.; Wuilloud, Rodolfo G.

2016-10-01

This article presents an efficient, simple, and cost-effective method for the determination of trace amounts of Hg by vortex-assisted liquid-liquid microextraction (VALLME) coupled to microvolume UV-Vis spectrophotometry. This method correlates changes in the intensity of localized surface plasmon resonance (LSPR) of tetraoctylammonium bromide (TOABr) coated Au nanoparticles (NPs) after interaction with Hg2+ ion. Spectroscopic measurements of the TOABr-coated Au NPs phase with particular absorption properties (strong and well-defined absorption bands) after analyte extraction by VALLME, provide an accurate and sensitive determination of Hg in water samples, comparable with measurements obtained by atomic absorption spectrometry (AAS). Different variables including sample volume, extraction time, and TOABr-coated Au NPs dispersion volume were carefully studied; final experimental conditions were 5 mL, 120 μL and 5 min respectively. The limit of detection (LOD) was 0.8 ng mL- 1. The calibration curve was linear at concentrations between the limit of quantification (LOQ) (4.9 ng mL- 1) and up to at least 120 ng mL- 1 of Hg. The relative standard deviation for six replicate determinations of 20 ng mL- 1 of Hg was 4.7%. This method exhibited an excellent analytical performance in terms of selectivity and sensitivity and it was finally applied for Hg determination in spiked tap and mineral water samples.

Resonance Rayleigh scattering method for determination of 2-mercaptobenzothiazole using gold nanoparticles probe.

PubMed

Parham, Hooshang; Pourreza, Nahid; Marahel, Farzaneh

2015-01-01

A sensitive, simple and novel method was developed to determine 2-mercaptobenzothiazole (2MBT) in water samples. This method was based on the interaction between gold nanoparticles (AuNPs) and 2MBT followed by increasing of the resonance Rayleigh scattering (RRS) intensity of nanoparticles. The change in RRS intensity (ΔIRRS) was linearly correlated to the concentration of 2MBT over the ranges of 5.0-100.0 and 100.0-300.0 μg L(-1). 2MBT can be measured in a short time (5 min) without any complicated or time-consuming sample pretreatment process. Parameters that affect the RRS intensities such as pH, concentration of AuNPs, standing time, electrolyte concentration, and coexisting substances were systematically investigated and optimized. Interference tests showed that the developed method has a very good selectivity and could be used conveniently for determination of 2MBT. The limit of detection (LOD) and limit of quantification (LOQ) were 1.0 and 3.0 μg L(-1), respectively. Relative standard deviations (RSD) for 20.0 and 80.0 μg L(-1) of 2MBT were 1.1 and 2.3, respectively. Possible mechanisms for the RRS changes of AuNPs in the presence of 2MBT were discussed and the method was successfully applied for the analysis of real water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

A selective biomarker for confirming nitrofurazone residues in crab and shrimp using ultra-performance liquid chromatography-tandem mass spectrometry.

PubMed

Zhang, Shuai; Guo, Yuanming; Yan, Zhongyong; Sun, Xiumei; Zhang, Xiaojun

2015-12-01

Reliably detecting nitrofurazone (NFZ) residues in farmed crab and shrimp was previously hindered by lack of appropriately specific analytical methodology. Parent NFZ rapidly breaks down in meat, and the commonly used side-chain metabolite, semicarbazide (SEM), is non-specific as it occurs naturally in crustacean shell often leading to 'false positive' detections in meat. Using 5-nitro-2-furaldehyde (NF) as marker metabolite, following pre-column derivatization with 2,4-dinitrophenylhydrazine (DNPH), ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis in negative electrospray ionization mode enabled confirmation of NFZ residues in deliberately treated whole crab, crab meat and shrimp meat, with a limit of detection (LOD) and limit of quantification (LOQ) below 1 ng g(-1). Meanwhile, the derivatives of DNPH-NF were synthesized for the first time, purified by preparative liquid chromatography and structure characterized with nuclear magnetic resonance spectroscopy ((1)H-NMR). The purity of derivative was checked by ultra-performance liquid chromatography-tunable ultraviolet (UPLC-TUV), and the contents were beyond 99.9%. For comparison purposes, crustacean samples were analysed using both NF and SEM marker metabolites. NFZ treatment was revealed by both NF and SEM marker metabolites, but untreated crab also showed measurable levels of SEM which could potentially be misinterpreted as evidence of illegal NFZ use.

A HPLC-DAD method for the simultaneous determination of five marker components in the traditional herbal medicine Bangpungtongsung-san

PubMed Central

Weon, Jin Bae; Yang, Hye Jin; Ma, Jin Yeul; Ma, Choong Je

2011-01-01

Background: Bangpungtongsung-san, one of the traditional herbal medicines, was known to be a prescription for obesity. Objective: For the simultaneous determination of five components (paeoniflorin, 6-gingerol, decursin, geniposide, and glycyrrhizin) in Bangpungtongsung-san, a high-performance liquid chromatography with diode-array detector method was established. Materials and Methods: To develop the method, a reverse phase column, DIONEX C 18 (5 μm, 120 µ, 4.6 mm × 150 mm) was used. The mobile phase consisted of methanol and water using a gradient elution. The UV wavelength was set at 230, 240, and 254 nm. Method validation was accomplished by linearity, precision test, and recovery test. Results: All calibration curves of components showed good linearity (R 2 > 0.9959). The limit of detection (LOD) and limit of quantification (LOQ) ranged from 0.01 to 0.17 μg/ml and 0.04 to 0.53 μg/ml, respectively. The relative standard deviations (RSD) value of precision test, intraday and interday tests were less than 0.43% and 1.26%. In the recovery test, results of accuracy ranged from 95.27% to 107.70% with RSD values less than 2.21%. Conclusion: This developed method was applied to the commercial Bangpungtongsung-san sample and the five marker components were separated effectively without interference of any peaks of components. PMID:21472081

Development and Validation of a Liquid Chromatography-Tandem Mass Spectrometry Method Coupled with Dispersive Solid-Phase Extraction for Simultaneous Quantification of Eight Paralytic Shellfish Poisoning Toxins in Shellfish.

PubMed

Yang, Xianli; Zhou, Lei; Tan, Yanglan; Shi, Xizhi; Zhao, Zhiyong; Nie, Dongxia; Zhou, Changyan; Liu, Hong

2017-06-29

In this study, a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for simultaneous determination of eight paralytic shellfish poisoning (PSP) toxins, including saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins (GTX1-4) and the N -sulfo carbamoyl toxins C1 and C2, in sea shellfish. The samples were extracted by acetonitrile/water (80:20, v / v ) with 0.1% formic and purified by dispersive solid-phase extraction (dSPE) with C18 silica and acidic alumina. Qualitative and quantitative detection for the target toxins were conducted under the multiple reaction monitoring (MRM) mode by using the positive electrospray ionization (ESI) mode after chromatographic separation on a TSK-gel Amide-80 HILIC column with water and acetonitrile. Matrix-matched calibration was used to compensate for matrix effects. The established method was further validated by determining the linearity ( R ² ≥ 0.9900), average recovery (81.52-116.50%), sensitivity (limits of detection (LODs): 0.33-5.52 μg·kg -1 ; limits of quantitation (LOQs): 1.32-11.29 μg·kg -1 ) and precision (relative standard deviation (RSD) ≤ 19.10%). The application of this proposed approach to thirty shellfish samples proved its desirable performance and sufficient capability for simultaneous determination of multiclass PSP toxins in sea foods.

[Determination of fluorescent whitening agents in plastic food contact materials by high performance liquid chromatography with fluorescence detector].

PubMed

Jiao, Yanna; Ding, Li; Zhu, Shaohua; Fu, Shanliang; Gong, Qiang; Li, Hui; Wang, Libing

2013-01-01

A method for the determination of fluorescent whitening agents in plastic food contact materials by high performance liquid chromatography (HPLC) with fluorescence detector was developed. The samples were extracted with trichloromethane by sonication for 30 min at 40 degrees C. The HPLC method was performed on a column of Eclipse XDB-C18 (250 mm x 4.6 mm, 5 microm) by gradient elution using 5 mmol/L ammonium acetate and acetonitrile as the mobile phases, and detected by the fluorescence detector at an excitation wavelength of 350 nm and an emission wavelength of 430 nm. The experimental results indicated that the four fluorescent whitening agents were separated well. The limits of detection (LOD) (S/N = 3) were 0.3, 0.1, 0.05, 0.14 mg/L, and the limits of quantification (LOQ) (S/N = 10) were 1.0, 0.4, 0.2, 0.5 mg/L for 1,4-bis (4-cyanostyryl) benzene (C. I. 199), 1,4-bis (2-benzoxazolyl) naphthalene (C. I. 367), 4,4'-bis(2-methoxystyryl) biphenyl (C. I. 378) and 2,5-thiophenediylbis (5-tert-butyl-1,3-benzoxazole) (C. I. 184), respectively. Good linearities with correlation coefficients (r2) not less than 0.991 were obtained. The proposed method is simple, accurate, sensitive and can meet the requirements of the routine determination of fluorescent whitening agents in entry-exit products.

Comparison of Clean-Up Methods for Ochratoxin A on Wine, Beer, Roasted Coffee and Chili Commercialized in Italy

PubMed Central

Prelle, Ambra; Spadaro, Davide; Denca, Aleksandra; Garibaldi, Angelo; Gullino, Maria Lodovica

2013-01-01

The most common technique used to detect ochratoxin A (OTA) in food matrices is based on extraction, clean-up, and chromatography detection. Different clean-up cartridges, such as immunoaffinity columns (IAC), molecular imprinting polymers (MIP), Mycosep™ 229, Mycospin™, and Oasis® HLB (Hydrophilic Lipophilic balance) as solid phase extraction were tested to optimize the purification for red wine, beer, roasted coffee and chili. Recovery, reproducibility, reproducibility, limit of detection (LOD) and limit of quantification (LOQ) were calculated for each clean-up method. IAC demonstrated to be suitable for OTA analysis in wine and beer with recovery rate >90%, as well as Mycosep™ for wine and chili. On the contrary, MIP columns were the most appropriate to clean up coffee. A total of 120 samples (30 wines, 30 beers, 30 roasted coffee, 30 chili) marketed in Italy were analyzed, by applying the developed clean-up methods. Twenty-seven out of 120 samples analyzed (22.7%: two wines, five beers, eight coffees, and 12 chili) resulted positive to OTA. A higher incidence of OTA was found in chili (40.0%) more than wine (6.6%), beers (16.6%) and coffee (26.6%). Moreover, OTA concentration in chili was the highest detected, reaching 47.8 µg/kg. Furthermore, three samples (2.5%), two wines and one chili, exceeded the European threshold. PMID:24152987

Microwave assisted solid phase extraction for separation preconcentration sulfamethoxazole in wastewater using tyre based activated carbon as solid phase material prior to spectrophotometric determination.

PubMed

Mogolodi Dimpe, K; Mpupa, Anele; Nomngongo, Philiswa N

2018-01-05

This work was chiefly encouraged by the continuous consumption of antibiotics which eventually pose harmful effects on animals and human beings when present in water systems. In this study, the activated carbon (AC) was used as a solid phase material for the removal of sulfamethoxazole (SMX) in wastewater samples. The microwave assisted solid phase extraction (MASPE) as a sample extraction method was employed to better extract SMX in water samples and finally the analysis of SMX was done by the UV-Vis spectrophotometer. The microwave assisted solid phase extraction method was optimized using a two-level fractional factorial design by evaluating parameters such as pH, mass of adsorbent (MA), extraction time (ET), eluent ratio (ER) and microwave power (MP). Under optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.5μgL -1 and 1.7μgL -1 , respectively, and intraday and interday precision expressed in terms of relative standard deviation were >6%.The maximum adsorption capacity was 138mgg -1 for SMX and the adsorbent could be reused eight times. Lastly, the MASPE method was applied for the removal of SMX in wastewater samples collected from a domestic wastewater treatment plant (WWTP) and river water. Copyright © 2017 Elsevier B.V. All rights reserved.

[Determination of five representative ultraviolet filters in water by gas chromatography-mass spectrometry].

PubMed

Ding, Yiran; Huang, Yun; Zhao, Tingting; Cai, Qian; Luo, Yu; Huang, Bin; Zhang, Yuxia; Pan, Xuejun

2014-06-01

A method for the determination of five representative organic UV filters: ethylhexyl methoxycinnamate (EHMC), benzophenone-3 (BP-3), 4-methylbenzylidene camphor (4-MBC), octocrylene (OC), homosalate (HMS) in water was investigated. The method was ased on derivatization, solid phase extraction (SPE), followed by determination with gas chromatography-mass spectrometry (GC-MS). The variables involved in the derivatization of BP-3 and HMS were optimized, and SPE conditions were studied. For derivatization, 100 microL N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) was used as derivatization reagent and reacted with BP-3 and HMS at 100 degrees C for 100 min. For SPE, the pH value of water sample was adjusted to 3-5. The Oasis HLB cartridges were employed and the solution of ethyl acetate and dichloromethane (1 : 1, v/v) was used as the eluting solvent, and good recoveries of the target compounds were obtained. The limits of detection (LODs) and the limits of quantification (LOQs) for the five target compounds in water samples were 0.5-1.2 ng/L and 1.4-4.0 ng/L, respectively. The recoveries of spiked water samples were 87.85%-102.34% with good repeatability and reproducibility (RSD < 5%, n = 3) for all the target compounds. Finally, the validated method was applied to analysis the representative UV filters in water samples collected from a wastewater treatment plant in Kunming city of Yunnan province.

A rapid UPLC method for simultaneous determination of eleven components in ‘Ge-Gen-Qin-Lian’ decoction

PubMed Central

An, Rui; You, Lisha; Zhang, Yizhu; Wang, Xinhong; Ma, Yuemin

2014-01-01

Background: ‘Ge-Gen-Qin-Lian’ Decoction derived from ‘Shang-Han-Lun’ compiled by Zhang Zhongjing. It is widely used in the treatment of acute gastroenteritis, bacillary dysentery, virus diarrhea. This paper describes a sensitive and specific assay for the determination of the 11-marker compounds using ultra performance liquid chromatography (UPLC). Objective: To develop an UPLC method for simultaneous determination of 11 bioactive compounds in ‘Ge-Gen-Qin-Lian’ preparations. Materials and Methods: The chromatography analysis was performed on an Agilent Proshell 120 EC-C18 column (4.6 × 50 mm, 2.7 μm) at 30°C with a gradient elution of methanol, 0.5% formic acid and 0.5% ammonium acetate at a flow rate 1.0 ml/min and UV detected at 270 nm. Results: All calibration curves showed good linear regression (r ≥ 0.9993) within tested ranges. Limits of detection (LOD) and limits of quantification (LOQ) fell in the range between 0.0691-1.04 μg/ml and 0.23–3.43 μg/ml, respectively. The mean recovery of each herbal medicine ranged from 96.60 to 102.11%. Conclusion: The method was validated for repeatability, precision, stability, accuracy, and selectivity. The validated method was successfully applied to simultaneous analysis of these active components in ‘Ge-Gen-Qin-Lian’ decoction. PMID:25422547

Comparison of three different C18 HPLC columns with different particle sizes for the optimization of aflatoxins analysis.

PubMed

Medina, A; Magan, N

2012-03-15

In this work we compared the performance of chromatography columns with particles of 5 and 3 μm with the new 2.7 μm solid core particles for the analysis of aflatoxins B1, G1, B2, and G2 using trifluoroacetic acid pre-column derivatization. Three different columns have been used and chromatographic parameters as retention time, resolution, limit of detection (LOD), limit of quantification (LOQ) were obtained from all of them and compared. The results show that comparing with the traditional columns, shorter columns (100 mm × 4.6 mm) with the new solid core particles are suitable for the analysis of these mycotoxins and allowed the reduction of the analysis time by 45.5% and 33.3% with respect to columns with particle size 5 μm (150 mm × 4.6 mm) and 3 μm (150 mm × 4.6 mm) respectively, without any detrimental effect on performance. This leads to the reduction of the analysis costs by saving on organic solvents and increasing the total number of analyses per day. The capability of these columns for analyzing samples, in different culture media, was assessed by analyzing different samples from: yeasts extract sucrose medium, corn meal agar medium and fresh hazelnut media. Copyright © 2012 Elsevier B.V. All rights reserved.

Magnetic nano graphene oxide as solid phase extraction adsorbent coupled with liquid chromatography to determine pseudoephedrine in urine samples.

PubMed

Taghvimi, Arezou; Hamishehkar, Hamed; Ebrahimi, Mahmoud

2016-01-15

This paper reports on a method based on magnetic solid phase extraction (MSPE) for the determination of pseudoephedrine. Magnetic nanographene oxide (MNGO) was applied as a new adsorbent for the extraction of pseudoephedrine from urine samples. Synthesis of MNGO was characterized by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The main factors influencing extraction efficiency, including the amounts of sample volume, amount of adsorbent, type and amount of extraction organic solvent, time of extraction and desorption, pH, ionic strength of extraction medium, and agitation rate, were investigated and optimized. Under optimized extraction conditions, a good linearity was observed in the range of 100-2000ng/mL with a correlation coefficient of 0.9908 (r(2)). Limit of detection (LOD) and limit of quantification (LOQ) were 25 and 82.7ng/mL, respectively. Inter-day and intra-day precision and accuracy were 6.01 and 0.34 (%), and 8.70 and 0.29 (%), respectively. The method was applied for the determination of pseudoephedrine in urine samples of volunteers receiving pseudoephedrine with the recovery of 96.42. It was concluded that the proposed method can be applied in diagnostic clinics. Copyright © 2015 Elsevier B.V. All rights reserved.

[Determination of deoxynivalenol in grain and its products by solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry].

PubMed

Huang, Juan; Chen, Guosong; Zhang, Xiaoyan; Shen, Chongyu; Lü, Chen; Wu, Bin; Liu, Yan; Chen, Huilan; Ding, Tao

2012-11-01

A method was established for the determination of deoxynivalenol (vomitoxin) in grain and its products based on solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was firstly extracted by acetonitrile-water (84:16, v/v). The extract was then cleaned-up by an HLB solid phase extraction cartridge. The separation was carried out on a Phenomenex Kinetex C18 column (100 mm x4. 6 mm, 2.6 microm) with a gradient elution using 0.3% per hundred ammonia solution-acetonitrile as mobile phases. The analysis of deoxynivalenol was performed under electrospray negative ionization mode. The limit of detection (LOD, S/N= 3) and the limit of quantification (LOQ, S/N = 10) were 20 microg/kg and 50 microg/kg, respectively. A good linearity (r > 0.99) was achieved for the target compound over the range of 20-1000 pg/L. The recoveries at the three spiked levels (50, 100, 500 microg/kg) in the blank matrices such as flour, barley, soybean, rice, cornmeal, cassava and wheat, were varied from 75.6% to 111.0% with the relative standard deviations no more than 13. 0%. The method is accurate, efficient, sensitive and practical. The cost of pretreatment is obviously reduced by replacing immunoaffinity columns and Mycosep columns with HLB columns which have the same purification effect.

Electrochemical oxidation mechanism of eugenol on graphene modified carbon paste electrode and its analytical application to pharmaceutical analysis.

PubMed

Yildiz, Gulcemal; Aydogmus, Zeynep; Cinar, M Emin; Senkal, Filiz; Ozturk, Turan

2017-10-01

Electrochemical properties of eugenol were investigated on a graphene modified carbon paste electrode (CPE) by using voltammetric methods, which exhibited a well-defined irreversible peak at about 0.7V vs Ag/AgCl, NaCl (3M) in Britton-Robinson buffer at pH 2.0. Mechanism of the electrochemical reaction of eugenol was studied by performing density functional theory (DFT) computations and mass spectroscopic analysis. (CPCM:water)-wB97XD/aug-cc-PVTZ//(CPCM:water)-wB97XD/6-31G(d) level calculations predicted that the formation of product P2, possessing a para-quinoid structure, is preferred rather than the product P1, suggested in the literature, having an ortho-quinoid system. Determination of eugenol in a pharmaceutical sample was realized in the light of the electrochemical findings, and a validated voltammetric method for quantitative analysis of eugenol in a pharmaceutical formulation was proposed. The differential pulse voltammogram (DPV) peak currents were found to be linear in the concentration range of 1.0 × 10 -7 to 1.7 × 10 -5 M. The limit of detection (LOD) and the limit of quantification (LOQ) were obtained to be 7.0 × 10 -9 and 2.3 × 10 -8 , respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Mesoporous-silica nanofluidic channels for quick enrichment/extraction of trace pesticide molecules

NASA Astrophysics Data System (ADS)

Xu, Pengcheng; Chen, Chuanzhao; Li, Xinxin

2015-11-01

As nanofluidic channels, uniaxially oriented mesoporous-silica is, for the first time, in-situ self-assembled in a microfluidic chip for quick enrichment/extraction of ng L-1(ppt)-level organo-phosphorous (OP) pesticide residue from aqueous solution to ethanol. This micro/nano combined pre-treatment chip is essential for following gas chromatography-mass spectrometry (GC-MS) quantitative analysis. Featuring huge surface area and dense silanol groups at the inwall surface, the mesoporous-silica is uniaxially self-assembled in a micro-reservoir to form a pile of nanofluidic channels (diameter = 2.1 nm). The captured/enriched pesticide molecules in the nanochannels can be efficiently extracted by much smaller volume of ethanol due to its much higher solubility to OP. In our affirming experiment, three mixed OP pesticides of dichlorvos, paraoxon and chlorpyrifos (in water) are captured/enriched by the nano-channels and eluted/extracted by only 0.6 mL ethanol. The whole process only takes 16 min. The GC-MS quantitative results for the extracted three pesticides indicate that the extraction recovery achieves 80%. The achieved limit of quantification (LOQ) and the limit of detection (LOD) are 100 ng L-1 and 30 ng L-1, respectively. The nanofluidic-channel pre-treatment technique is promising in various application fields like agriculture and food safety security.

Ultrasensitive Determination of Piroxicam at Diflunisal-Derived Gold Nanoparticle-Modified Glassy Carbon Electrode

NASA Astrophysics Data System (ADS)

Shaikh, Tayyaba; uddin, SiraJ; Talpur, Farah N.; Khaskeli, Abdul R.; Agheem, Muhammad H.; Shah, Muhammad R.; Sherazi, Tufail H.; Siddiqui, Samia

2017-10-01

We present a simple and green approach for synthesis of gold nanoparticles (AuNps) using analgesic drug diflunisal (DF) as capping and stabilizing agent in aqueous solution. Characterization of the synthesized diflunisal-derived gold nanoparticles (DF-AuNps) was performed by ultraviolet-visible (UV-Vis) spectroscopy, revealing the surface plasmon absorption band at 520 nm under optimized experimental conditions. Fourier-transform infrared (FTIR) spectroscopy established the effective interaction of the capping agent with the AuNps. Topographical features of the synthesized DF-AuNps were assessed by atomic force microscopy (AFM), revealing average particle height of 29 nm to 32 nm. X-ray diffractometry was used to study the crystalline nature, revealing that the synthesized DF-AuNps possessed excellent crystalline properties. The synthesized DF-AuNps were employed to modify the surface of glassy carbon electrode (GCE) for selective determination of piroxicam (PX) using differential pulse voltammetry technique. The fabricated Nafion/DF-AuNps/GCE sensor exhibited high sensitivity compared with bare GCE. The current response of the fabricated sensor was found to be linear in the PX concentration range of 0.5 μM to 50 μM, with limit of detection (LOD) and limit of quantification (LOQ) of 50 nM and 150 nM, respectively. The proposed sensor was successfully utilized for sensitive and rapid determination of PX in human serum, urine, and pharmaceutical samples.

A stability indicating HPLC method for determination of mebeverine in the presence of its degradation products and kinetic study of its degradation in oxidative condition

PubMed Central

Souri, E.; Aghdami, A. Negahban; Adib, N.

2014-01-01

An HPLC method for determination of mebeverine hydrochloride (MH) in the presence of its degradation products was developed. The degradation of MH was studied under hydrolysis, oxidative and photolysis stress conditions. Under alkaline, acidic and oxidative conditions, degradation of MH was observed. The separation was performed using a Symmetry C18 column and a mixture of 50 mM KH2PO4, acetonitrile and tetrahydrfuran (THF) (63:35:2; v/v/v) as the mobile phase. No interference peaks from degradation products in acidic, alkaline and oxidative conditions were observed. The linearity, accuracy and precision of the method were studied. The method was linear over the range of 1-100 μg/ml MH (r2>0.999) and the CV values for intra-day and inter-day variations were in the range of 1.0-1.8%. The limit of quantification (LOQ) and the limit of detection (LOD) of the method were 1.0 and 0.2 μg/ml, respectively. Determination of MH in pharmaceutical dosage forms was performed using the developed method. Furthermore the kinetics of the degradation of MH in the presence of hydrogen peroxide was investigated. The proposed method could be a suitable method for routine quality control studies of mebeverine dosage forms. PMID:25657790

A stability indicating HPLC method for determination of mebeverine in the presence of its degradation products and kinetic study of its degradation in oxidative condition.

PubMed

Souri, E; Aghdami, A Negahban; Adib, N

2014-01-01

An HPLC method for determination of mebeverine hydrochloride (MH) in the presence of its degradation products was developed. The degradation of MH was studied under hydrolysis, oxidative and photolysis stress conditions. Under alkaline, acidic and oxidative conditions, degradation of MH was observed. The separation was performed using a Symmetry C18 column and a mixture of 50 mM KH2PO4, acetonitrile and tetrahydrfuran (THF) (63:35:2; v/v/v) as the mobile phase. No interference peaks from degradation products in acidic, alkaline and oxidative conditions were observed. The linearity, accuracy and precision of the method were studied. The method was linear over the range of 1-100 μg/ml MH (r(2)>0.999) and the CV values for intra-day and inter-day variations were in the range of 1.0-1.8%. The limit of quantification (LOQ) and the limit of detection (LOD) of the method were 1.0 and 0.2 μg/ml, respectively. Determination of MH in pharmaceutical dosage forms was performed using the developed method. Furthermore the kinetics of the degradation of MH in the presence of hydrogen peroxide was investigated. The proposed method could be a suitable method for routine quality control studies of mebeverine dosage forms.

Multilocation field trials for risk assessment of a combination fungicide Fluopicolide + Propamocarb in tomato.

PubMed

Sharma, K K; Shukla, V R; Patel, A R; Vaghela, K M; Patel, H K; Shah, Paresh G; Banerjee, Hemanta; Banerjee, Tirthankar; Hudait, Ram K; Sharma, Debi; Sahoo, S K; Singh, Balwinder; Tripathy, Vandana

2016-11-01

Dissipation kinetics of two systemic fungicides, namely fluopicolide and propamocarb used as a combination formulation (Infinito 68.75 SC), were studied on tomato at four different locations by the All India Network Project on Pesticide Residues to recommend their pre-harvest interval (PHI) and to propose the maximum residue limits (MRL) for the two fungicides based on chronic hazard exposure assessment. The combination fungicide was sprayed thrice at the recommended dosage of 93.75 g a.i./ha fluopicolide and 937.50 g a.i./ha propamocarb as well as at double the recommended dosage of 187.50 g a.i./ha fluopicolide and 1875.0 g a.i./ha propamocarb on tomato crops and the residues were monitored periodically by GC-MS. The fungicides dissipated to below the limit of quantification (LOQ) within 10 to 15 days, with a half-life of 2-4 days for fluopicolide and 1-2 days for propamocarb. Taking into consideration the MRLs of codex and calculations made using the method of MRL fixation of the Food Safety and Standard Authority of India (FSSAI) as well as the Organization for Economic Co-operation and Development (OECD) calculator, MRL of 5 mg/kg is proposed for fluopicolide and 15 mg/kg for propamocarb, following critical exposure of the commodity considering PHI of 1 day.

Ionic liquid-based microwave-assisted extraction for the determination of flavonoid glycosides in pigeon pea leaves by high-performance liquid chromatography-diode array detector with pentafluorophenyl column.

PubMed

Wei, Wei; Fu, Yu-jie; Zu, Yuan-gang; Wang, Wei; Luo, Meng; Zhao, Chun-jian; Li, Chun-ying; Zhang, Lin; Wei, Zuo-fu

2012-11-01

In this study, an ionic liquid-based microwave-assisted extraction (ILMAE) followed by high-performance liquid chromatography-diode array detector with a pentafluorophenyl column for the extraction and quantification of eight flavonoid glycosides in pigeon pea leaves is described. Compared with conventional extraction methods, ILMAE is a more effective and environment friendly method for the extraction of nature compounds from herbal plants. Nine different types of ionic liquids with different cations and anions were investigated. The results suggested that varying the anion and cation had significant effects on the extraction of flavonoid glycosides, and 1.0 M 1-butyl-3-methylimidazolium bromide ([C4MIM]Br) solution was selected as solvent. In addition, the extraction procedures were also optimized using a series of single-factor experiments. The optimum parameters were obtained as follows: extraction temperature 60°C, liquid-solid ratio 20:1 mL/g and extraction time 13 min. Moreover, an HPLC method using pentafluorophenyl column was established and validated. Good linearity was observed with the regression coefficients (r(2)) more than 0.999. The limit of detection (LODs) (S/N = 3) and limit of quantification (LOQs) (S/N = 10) for the components were less than 0.41 and 1.47 μg/mL, respectively. The inter- and intraday precisions that were used to evaluate the reproducibility and relative standard deviation (RSD) values were less than 4.57%. The recoveries were between 97.26 and 102.69%. The method was successfully used for the analysis of samples of pigeon pea leaves. In conclusion, the developed ILMAE-HPLC-diode array detector using pentafluorophenyl column method can be applied for quality control of pigeon pea leaves and related medicinal products. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of monoclonal antibody-based sensitive ELISA for the determination of Cry1Ie protein in transgenic plant.

PubMed

Zhang, Yuwen; Zhang, Wei; Liu, Yan; Wang, Jianhua; Wang, Guoying; Liu, Yunjun

2016-11-01

Cry1Ie is a kind of Bacillus thuringiensis (Bt) toxin protein which has a different action model than the Cry1Ab and Cry1Ac protein. The transgenic maize expressing Cry1Ie might be commercially used in the near future and it is urgent to develop a method to detect Cry1Ie protein in transgenic plants and their products. To develop an ELISA method, Cry1Ie protein was expressed in Escherichia coli strain Transetta DE3, purified with the Ni-NTA spin columns, and then validated by sequencing. Bioassay results showed that the purified Cry1Ie protein was highly toxic to the Asian corn borer. The polyclonal antibody (pAb) and the specific monoclonal antibody (mAb) 1G 4 2D 6 were generated from rabbit and mice which were immunized with Cry1Ie protein, respectively. Western blotting of crude Cry1Ie protein extracts was established by employing mAb 1G 4 2D 6 , whereas the mAb 1G 4 2D 6 negligibly recognized other Bt proteins. Sandwich ELISA against Cry1Ie protein was established by coating with pAb and detecting with mAb 1G 4 2D 6 . The limit of detection (LOD), the limit of quantification (LOQ), and the quantification range of the assay in different matrices of maize plant were determined as 0.27-0.51, 0.29-0.78, and 0.45-15.71 ng/mL, respectively. Recoveries of Cry1Ie protein spiked in different maize tissues ranged from 75.1 to 99.5 %. The established sandwich ELISA was verified using transgenic maize overexpressing Cry1Ie. The results in this study suggested that the established ELISA method is effective for detecting Cry1Ie protein in transgenic plants.

Molecular and immunological approaches in quantifying the air-borne food allergen tropomyosin in crab processing facilities.

PubMed

Kamath, Sandip D; Thomassen, Marte R; Saptarshi, Shruti R; Nguyen, Hong M X; Aasmoe, Lisbeth; Bang, Berit E; Lopata, Andreas L

2014-09-01

Tropomyosin is a cross-reactive allergenic protein present in ingested shellfish species. Exposure and sensitization to this protein via inhalation is particularly important in the crustacean processing industry where workers are continuously exposed to the aerosolized form of this allergen. The aim of this study was to develop an antibody-based immunoassay to enable the specific and sensitive quantification of aerosolized tropomyosin present in the environment of two crab processing facilities. Anti-tropomyosin antibody was generated in rabbits against tropomyosins from four different crustacean species. These antibodies were purified using recombinant tropomyosin using an immuno-affinity column. The recombinant tropomyosin was also used as an allergen standard for the sandwich ELISA. In order to quantify aerosolized tropomyosin, air collection was performed in the personal breathing zone of 80 workers during two crab processing activities, edible crab (Cancer pagurus) and king crab (Paralithodes camtschaticus) using polytetrafluoroethylene filters. The purified antibody was able to detect tropomyosin selectively from different crustaceans but not from vertebrate sources. The limit of detection (LOD) for the developed sandwich ELISA was 60 picogram/m(3) and limit of quantitation (LOQ) 100 picogram/m(3). Immunoassay validation was based on linearity (R(2) 0.999), matrix interference test (78.8±6.5%), intra-assay CV (9.8%) and inter-assay CV (11%). The novel immunoassay was able to successfully identify working activities, which generated low, medium or high concentrations of the aerosolized food allergen. We describe an IgG antibody-based immunoassay for quantification of the major food allergen tropomyosin, with high sensitivity and specificity. This modified immunological approach can be adapted for the detection of other aerosolized food allergens, assisting in the identification of high-risk allergen exposure areas in the food industry. Copyright © 2014 Elsevier GmbH. All rights reserved.

Complexity in estimation of esomeprazole and its related impurities' stability in various stress conditions in low-dose aspirin and esomeprazole magnesium capsules.

PubMed

Reddy, Palavai Sripal; Hotha, Kishore Kumar; Sait, Shakil

2013-01-01

A complex, sensitive, and precise high-performance liquid chromatographic method for the profiling of impurities of esomeprazole in low-dose aspirin and esomeprazole capsules has been developed, validated, and used for the determination of impurities in pharmaceutical products. Esomeprazole and its related impurities' development in the presence of aspirin was traditionally difficult due to aspirin's sensitivity to basic conditions and esomeprazole's sensitivity to acidic conditions. When aspirin is under basic, humid, and extreme temperature conditions, it produces salicylic acid and acetic acid moieties. These two byproducts create an acidic environment for the esomeprazole. Due to the volatility and migration phenomenon of the produced acetic acid and salicylic acid from aspirin in the capsule dosage form, esomeprazole's purity, stability, and quantification are affected. The objective of the present research work was to develop a gradient reversed-phase liquid chromatographic method to separate all the degradation products and process-related impurities from the main peak. The impurities were well-separated on a RP8 column (150 mm × 4.6mm, X-terra, RP8, 3.5μm) by the gradient program using a glycine buffer (0.08 M, pH adjusted to 9.0 with 50% NaOH), acetonitrile, and methanol at a flow rate of 1.0 mL min(-1) with detection wavelength at 305 nm and column temperature at 30°C. The developed method was found to be specific, precise, linear, accurate, rugged, and robust. LOQ values for all of the known impurities were below reporting thresholds. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis, and thermal degradation in the presence of aspirin. The developed RP-HPLC method was validated according to the present ICH guidelines for specificity, linearity, accuracy, precision, limit of detection, limit of quantification, ruggedness, and robustness.

High-performance liquid chromatographic determination of pantoprazole and its main impurities in pharmaceuticals.

PubMed

Letica, Jelena; Marković, Slavko; Zirojević, Jelena; Nikolić, Katarina; Agbaba, Danica

2010-01-01

An RP-HPLC method for simultaneous separation and quantification of pantoprazole and its five main impurities in pharmaceutical formulations was developed and validated. The separation was accomplished on a Zorbax Eclipse XDB C18 column (5 microm particle size, 150 x 4.6 mm id) using a gradient with mobile phase A [buffer-acetonitrile (70 + 30, v/v)], and mobile phase B [buffer-acetonitrile (30 + 70, v/v)]. The buffer was 0.01 M ammonium acetate solution with addition of 1 mL triethylamine/L of the solution, adjusted to pH 4.5 with orthophosphoric acid. The eluent flow rate was 1 mL/min, the temperature of the column was 30 degrees C, and the eluate was monitored at 290 nm. Linearity (r = 0.999), recovery (97.6-105.8%), RSD (0.55-1.90%), and LOQ (0.099-1.48 microg/mL) were evaluated and found to be satisfactory. The proposed method can be used for simultaneous identification and quantification of the analyzed compounds in pharmaceutical formulations.

Semi-preparative HPLC preparation and HPTLC quantification of tetrahydroamentoflavone as marker in Semecarpus anacardium and its polyherbal formulations.

PubMed

Aravind, S G; Arimboor, Ranjith; Rangan, Meena; Madhavan, Soumya N; Arumughan, C

2008-11-04

Application of modern scientific knowledge coupled with sensitive analytical technique is important for the quality evaluation and standardization of polyherbal formulations. Semecarpus anacardium, an important medicinal plant with wide medicinal properties, is frequently used in a large number of traditional herbal preparations. Tetrahydroamentoflavone (THA), a major bioactive biflavonoid was selected as a chemical marker of S. anacardium and RP-semi-preparative HPLC conditions were optimized for the isolation of tetrahydroamentoflavone. HPTLC analytical method was developed for the fingerprinting of S. anacardium flavonoids and quantification of tetrahydroamentoflavone. The method was validated in terms of their linearity, LOD, LOQ, precision and accuracy and compared with RP-HPLC-DAD method. The methods were demonstrated for the chemical fingerprinting of S. anacardium plant parts and some commercial polyherbal formulations and the amount of tetrahydroamentoflavone was quantified. HPTLC analysis showed that S. anacardium seed contained approximately 10 g kg(-1) of tetrahydroamentoflavone. The methods were able to identify and quantify tetrahydroamentoflavone from complex mixtures of phytochemicals and could be extended to the marker-based standardization of polyherbal formulations, containing S. anacardium.

Flavanol Quantification of Grapes via Multiple Reaction Monitoring Mass Spectrometry. Application to Differentiation among Clones of Vitis vinifera L. cv. Rufete Grapes.

PubMed

García-Estévez, Ignacio; Alcalde-Eon, Cristina; Escribano-Bailón, M Teresa

2017-08-09

The determination of the detailed flavanol composition in food matrices is not a simple task because of the structural similarities of monomers and, consequently, oligomers and polymers. The aim of this study was the development and validation of an HPLC-MS/MS-multiple reaction monitoring (MRM) method that would allow the accurate and precise quantification of catechins, gallocatechins, and oligomeric proanthocyanidins. The high correlation coefficients of the calibration curves (>0.993), the recoveries not statistically different from 100%, the good intra- and interday precisions (<5%), and the LOD and LOQ values, low enough to quantify flavanols in grapes, are good results from the method validation procedure. Its usefulness has also been tested by determining the detailed composition of Vitis vinifera L. cv. Rufete grapes. Seventy-two (38 nongalloylated and 34 galloylated) and 53 (24 procyanidins and 29 prodelphinidins) flavanols have been identified and quantified in grape seed and grape skin, respectively. The use of HCA and PCA on the detailed flavanol composition has allowed differentiation among Rufete clones.

Development and validation of a reversed-phase high-performance thin-layer chromatography-densitometric method for determination of atorvastatin calcium in bulk drug and tablets.

PubMed

Shirkhedkar, Atul A; Surana, Sanjay J

2010-01-01

Atorvastatin calcium is a synthetic HMG-CoA reductase inhibitor that is used as a cholesterol-lowering agent. A simple, sensitive, selective, and precise RP-HPTLC-densitometric determination of atorvastatin calcium both as bulk drug and from pharmaceutical formulation was developed and validated according to International Conference on Harmonization guidelines. The method used aluminum sheets precoated with silica gel 60 RP18F254S as the stationary phase, and the mobile phase consisted of methanol-water (3.5 + 1.5, v/v). The system gave a compact band for atorvastatin calcium with an Rf value of 0.62 +/- 0.02. Densitometric quantification was carried out at 246 nm. The linear regression analysis data for the calibration plots showed a good linear relationship with r = 0.9992 in the working concentration range of 100-800 ng/band. The method was validated for precision, accuracy, ruggedness, robustness, specificity, recovery, LOD, and LOQ. The LOD and LOQ were 6 and 18 ng, respectively. The drug underwent hydrolysis when subjected to acidic conditions and was found to be stable under alkali, oxidation, dry heat, and photodegradation conditions. Statistical analysis proved that the developed RP-HPTLC-densitometry method is reproducible and selective and that it can be applied for identification and quantitative determination of atorvastatin calcium in bulk drug and tablet formulation.

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

PubMed

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

2014-01-15

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

High Incidence and Levels of Ochratoxin A in Wines Sourced from the United States.

PubMed

De Jesus, Christopher Lawrence; Bartley, Amanda; Welch, Aaron Z; Berry, John P

2017-12-21

Ochratoxin A (OTA) is one of the most prevalent mycotoxin contaminants of food crops. Among the agricultural products consequently contaminated by OTA is wine. In the present study, a sample of wines sourced from the United States was assessed for OTA. Wines were primarily analyzed by high-performance liquid chromatography with fluorescence detection (HPLC-FD) coupled to a liquid-liquid extraction (LLE) technique which was developed and validated as a simplified sample preparation approach. More than 85% of the wines evaluated were found to contain OTA, at levels above the limit-of-detection (LOD = 0.1 µg L -1 ), and 76% were above the limit-of-quantitation (LOQ = 0.3 µg L -1 ) for the LLE/HPLC-FD method. More than two-thirds of the wines above the LOQ were found to exceed 1 µg L -1 . Complementary analysis by HPLC coupled to tandem mass spectrometry (HPLC-MS/MS) confirmed OTA in 74% of the OTA-positive wines (i.e., >LOQ by HPLC-FD). Overall, both the occurrence and measured levels of OTA were generally high, specifically relative to previous assessments of OTA in wine, and two of the wines were above the only current (European Union) regulatory limit of two parts-per-billion (ppb, ~2 µg L -1 ). Possible trends with respect to geographical region and/or growing climate are noted. As the first assessment of U.S. wines in more than a decade, the overall high occurrence and levels of OTA in wine, and possible geographic and climatic trends, point to a need for regular surveillance of wines, as well as investigation of the relevant contributors to OTA occurrence toward mitigating contamination and exposure risks.