bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Ginsenosides in Panax ginseng Roots by Liquid Chromatography with Evaporative Light-Scattering Detection
Authors: Fuzzati Nicola , Gabetta Bruno , Jayakar Kaishik , Pace Roberto , Ramaschi Giuseppe , Villa Francesco
Published: February 2020

A liquid chromatographic method was developed and validated for the determination of ginsenosides in Panax ginseng roots by using evaporative light-scattering detection. Eighteen ginsenosides were separated on a reversed-phase C18 column with water–ammonium acetate–acetonitrile as the mobile phase. The method is suitable for the routine determination of ginsenosides in P. ginseng roots and extracts. The validation of the method was comprehensive for efficiency and recovery optimization of the P. ginseng roots extraction, specificity by liquid chromatography/mass spectrometry, linearity, stability, reproducibility, repeatability, intermediate precision, and robustness.
Molecular Detection of Burkholderia cepacia in Toiletry, Cosmetic, and Pharmaceutical Raw Materials and Finished Products
Authors: Jimenez Luis , Smalls Stacey
Published: February 2020

A polymerase chain reaction (PCR) assay was developed and compared with standard methods for rapid detection of Burkholderia cepacia, a major industrial contaminant, in cosmetic and pharmaceutical raw materials and finished products. Artificially contaminated samples were incubated for 24 h in trypticase soy broth containing 4% Tween 20 and 0.5% soy lecithin. DNA was extracted from each sample using a proteinase K-tris-EDTA-Tween 20 treatment at 35°C. The extracted DNA was added to Ready-To-Go PCR beads and specific DNA primers for B. cepacia. The B. cepacia DNA primers coded for a 209-base pair (bp) fragment of the 16S rRNA ribosomal gene. No DNA amplification was observed in samples that were not spiked with B. cepacia. However, all contaminated samples showed the specific 209-bp fragment for B. cepacia. There was a 100% correlation between standard methods and the PCR assay. Standard microbiological methods required 5–6 days for isolation and identification of spiked microorganisms, whereas PCR detection and identification was completed in 27 h. PCR detection of B. cepacia allows for rapid quality evaluation of cosmetic and pharmaceutical raw materials and finished products.
Graphite Furnace Atomic Absorption Spectrometric Determination of Lead and Cadmium Extracted from Ceramic Foodware: Collaborative Study
Authors: Hight Susan C ,   Collaborators:, Ayyad N , Barnes B , Brown J , DePalma B , Gambaro M , Motley E , Shippey K
Published: February 2020

A modification of the official flame atomic absorption spectrometric (FAAS) method for determining lead and cadmium extracted from ceramic foodware was collaboratively studied. In the modified method, graphite furnace atomic absorption spectrometry (GFAAS) is substituted for FAAS. The modified method also includes mandatory quality control procedures to improve method performance. The extraction procedure of the official method (leaching with 4% acetic acid for 24 h at room temperature) remains unchanged. Seven laboratories analyzed blind duplicate portions of 3 ceramicware leach solutions containing Pb at concentrations of 0.0196, 0.403, and 3.73 μg/mL and Cd at concentrations of 0.00236, 0.0456, and 0.544 μg/mL. Performance of the modified method compared well with that of the official method. The repeatability relative standard deviation (RSDr) ranged from 0.87 to 6.7% for Pb and from 3.7 to 11% for Cd. The reproducibility relative standard deviation (RSDR) ranged from 4.5 to 12% for Pb and from 7.0 to 11% for Cd. Accuracy of collaborator results was 97–98% for Pb and 93–101% for Cd. Quality control results and quantitation limits were excellent. Method quantitation limits varied among laboratories from 0.005 to 0.019 μg/mL for Pb and from 0.0004 to 0.0019 μg/mL for Cd. The modified method was adopted First Action by AOAC INTERNATIONAL.
Determination of Metals in Foods by Atomic Absorption Spectrometry after Dry Ashing: NMKL1 Collaborative Study
Authors: Jorhem Lars ,   Collaborators:, Afthan G , Cumont G , Dypdahl H P , Gadd K , Havre G N , Julshamn K , Kåverud K , Lind B , Loimaranta J , Merseburg M , Olsson A , Piepponen S , Sundström B , Uppstad B J , Waaler T , Winnerstam L
Published: February 2020

A method for determination of lead, cadmium, zinc, copper, and iron in foods by atomic absorption spectrometry (AAS) after dry ashing at 450°C was collaboratively studied in 16 laboratories. The study was preceded by a practice round of familiarization samples and another round in which solutions were distributed and the metals were determined directly by AAS. The study included 5 different foods (liver paste, apple sauce, minced fish, wheat bran, and milk powder) and 2 simulated diets. A single analysis was carried out with each sample. Suitable sample combinations were used as split-level combinations for determination of the repeatability standard deviation. The reproducibility relative standard deviation for each of the elements ranged from 20 to 50% for lead concentrations of 0.040–0.25 mg/kg, from 12 to 352% for cadmium concentrations of 0.001–0.51 mg/kg, from 4 to 8% for zinc concentrations of 0.7–38 mg/kg, from 7 to 45% for copper concentrations of 0.51–45 mg /kg, and from 11 to 14% for iron concentrations of 4–216 mg/kg.
Microwave-Assisted Extraction and Accelerated Solvent Extraction with Ethyl Acetate–Cyclohexane before Determination of Organochlorines in Fish Tissue by Gas Chromatography with Electron-Capture Detection
Authors: Weichbrodt Marion , Vetter Walter , Luckas Bernd
Published: February 2020

Focused open-vessel microwave-assisted extraction (FOV–MAE), closed-vessel microwave-assisted extraction (CV–MAE), and accelerated solvent extraction (ASE) were used for extraction before determination of organochlorine compounds (polychlorinated biphenyls, DDT, toxaphene, chlordane, hexachlorobenzene, hexachlorocyclohexanes, and dieldrin) in cod liver and fish fillets. Wet samples were extracted without the time-consuming step of lyophilization or other sample-drying procedures. Extractions were performed with the solvent mixture ethyl acetate–cyclohexane (1 + 1, v/v), which allowed direct use of gel-permeation chromatography without solvent exchange. For FOV–MAE, the solvent mixture removed water from the sample matrix via azeotropic distillation. The status of water removal was controlled during extraction by measuring the temperature of the distillate. After water removal, the temperature of the distillate increased and the solvent mixture became less polar. Only the pure extraction solvent allowed quantitative extraction of the organochlorine compounds. For CV–MAE, water could not be separated during the extraction. For this reason, the extraction procedure for wet fish tissue required 2 extraction steps: the first for manual removal of coextracted water, and the second for quantitative extraction of the organochlorine compounds with the pure solvent. Therefore, CV–MAE is less convenient for samples with high water content. For ASE, water in the sample was bound with Na2SO4. The reproducibility for each technique was very good (relative standard deviation was typically <10%); the slightly varying levels were attributed to deviations during sample cleanup and the generally low levels.
Identification of Derivatives of Bisphenol A Diglycidyl Ether and Novolac Glycidyl Ether in Can Coatings by Liquid Chromatography/Ion Trap Mass Spectrometry
Authors: Berger Urs , Oehme Michael
Published: February 2020

A reversed-phase liquid chromatographic method combined with fluorescence and multiple mass spectrometric detection in series is presented for the separation and structure elucidation of bisphenol A diglycidyl ether (BADGE) and novolac glycidyl ether (NOGE) derivatives. Atmospheric pressure chemical ionization in the positive ion mode and collision induced fragmentation in the ion trap allowed identification of BADGE- and NOGE-related compounds originating from reactions of the glycidyl ethers with bisphenols, solvents, and chain stoppers. Two extracts from food-can coatings were investigated in detail. It was possible to elucidate the structures of many substances and consequently to draw conclusions about the production of the lacquers.
Simultaneous Determination of Ascorbic Acid and Acetylsalicylic Acid in Pharmaceutical Formulations
Authors: Toral M Ines , Lara Nelson , Richter Pablo , Tassara Andres , Tapia A E , Rodriguez Claudio
Published: February 2020

A direct, simple, and practical first-derivative spectrophotometric method is described for simultaneous determination of ascorbic acid and acetylsalicylic acid. The effects of the solvent, excipients, and spectral variables on the analytical signal were investigated. The drugs were determined simultaneously with a 0.01M methanolic hydrochloric acid solution as the solvent, and the signals were evaluated directly by using the zero-crossing method at 245.0 and 256.0 nm for acetylsalicylic acid and ascorbic acid, respectively. The method allows the simultaneous determinations of acetylsalicylic acid and ascorbic acid in the ranges of 6.6 × 10−6 to 1.5 × 10−4M and 3.4 × 10−6 to 2.0 × 10−4M, respectively, with standard deviation of <2.0%. The proposed method was applied to determinations of these drugs in tablets.
Determination of Locust Bean Gum and Guar Gum by Polymerase Chain Reaction and Restriction Fragment Length Polymorphism Analysis
Authors: Meyer Kerstin , Rosa Christelle , Hischenhuber Claudia , Meyer Rolf
Published: February 2020

A polymerase chain reaction (PCR) was developed to differentiate the thickening agents locust bean gum (LBG) and the cheaper guar gum in finished food products. Universal primers for amplification of the intergenic spacer region between trnL 3’ (UAA) exon and trnF (GAA) gene in the chloroplast (cp) genome and subsequent restriction analysis were applied to differentiate guar gum and LBG. The presence of <5% (w/w) guar gum powder added to LBG powder was detectable. Based on data obtained from sequencing this intergenic spacer region, a second PCR method for the specific detection of guar gum DNA was also developed. This assay detected guar gum powder in LBG in amounts as low as 1% (w/w). Both methods successfully detected guar gum and/or LBG in ice cream stabilizers and in foodstuffs, such as dairy products, ice cream, dry seasoning mixes, a finished roasting sauce, and a fruit jelly product, but not in products with highly degraded DNA, such as tomato ketchup and sterilized chocolate cream. Both methods detected guar gum and LBG in ice cream and fresh cheese at levels <0.1%.
Rapid Methods To Enumerate Escherichia coli in Foods Using 4-Methylumbelliferyl-ß-D-Glucuronide
Authors: Ekholm Diane F , Hirshfield Irvin N
Published: February 2020

Three methods to enumerate Escherichia coli in food were compared. They were based on AOAC methods using lauryl tryptose broth (LST) medium, LST-4-methylumbelliferyl-ß-D-glucuronide (MUG) medium, and a proposed method using regular LST in combination with E. coli (EC)–MUG medium. An efficacious and cost-effective method is needed that can detect E. Coli and does not produce false presumptive positives. We tested 170 cheeses, 40 frozen processed seafood samples, 210 tree nuts, and 40 other samples. The method of choice for enumerating E. Coli depends on the commodity itself. For a product, such as hard cheese or processed seafood, with a history of being negative for E. Coli and other lactose-fermenting organisms, the proposed method using regular LST/EC–MUG is a good choice. These samples were seldom presumptive positive in the primary LST medium. If gas was produced, EC–MUG was an effective secondary medium. No false positives (fluorescence) or negatives were detected in EC–MUG medium. For a product with a history of being positive for E. Coli and/or other lactose fermenting organisms, such as tree nutmeats or cheeses that are ripened by bacteria or mold, the method using LST–MUG is the method of choice. A presumptive positive in the LST–MUG medium was highly correlative with the biochemical tests that confirmed a sample contain E. Coli. For samples spiked with E. Coli, the results from each of these 3 methods were identical, and were consistent in enumerating E. Coli.
Isoflavone Glycosides from the Root Wood of Erythrina latissima
Authors: Wanjala Cornelius C W , Majinda Runner R T
Published: February 2020

The molecular structures of 3 isoflavone glycosides isolated from the root wood of Erythrina latissimawere established as 4′-hydroxyisoflavone-7-O-β-D-glucopyranoside (compound 1); 4′-hydroxyisoflavone-7-O-α-L-rhamnosyl (1→6)-β-D-glucopyranoside (compound 2); and a new compound 4′, 8-dimethoxy isoflavone-7-O-α-L-rhamnosyl(1→6)-β-D-glucopyranoside (8-O-methylretusin-7-O-α-L-rhamnosyl (1→6)-β-D-glucopyranoside) (compound 3).
Liquid Chromatographic Determination of Methyl Anthranilate in Artificially Flavored Nonalcoholic Beverages
Authors: Thompson Richard D , Quaife John T
Published: February 2020

A liquid chromatographic method was developed that provides a simple and rapid means of determining methyl anthranilate (MA) in carbonated and noncarbonated, artificial grape-flavored, nonalcoholic beverages. The proposed procedure, which was applied to 12 different products, uses a Nova-Pak C18 column, a mobile phase containing acetonitrile–0.025M KH2PO4 (40 + 60), pH 3.00, and UV detection at 220 nm. Assay values ranged from 0.35 to 16.6 Μg MA/mL. The intralaboratory precision (relative standard deviation) for the products ranged from 0.51 to 2.23% (n = 5), and recoveries via fortification ranged from 83.6 to 102.4%. The limits of quantitation and detection were 0.00417 and 0.00125 μg/mL, respectively, and the analyte response was linear over a 100-fold concentration range (0.0001–0.01 mg/mL).
LC/MS Confirmation of Ionophores in Animal Feeds
Authors: Turnipseed Sherri B , Roybal José E , Pfenning Allen P , Gonzales Steve A , Hurlbut Jeffrey A , Madson Mark R
Published: February 2020

A liquid chromatographic/mass spectrometric (LC/MS) electrospray confirmation method has been developed to confirm 4 ionophores (monensin, lasalocid, salinomycin, and narasin) in a variety of animal feeds using a single quadrupole mass spectrometer. The sodium ions of these compounds are dominant in the electrospray mass spectrum. Using optimized “in-source” collision induced dissociation, characteristic fragment ions seen previously using MS/MS can be observed. The drugs were extracted from the feed matrix using hexane–ethyl acetate and isolated using a silica solid-phase extraction cartridge. These ionophores were confirmed in both medicated feeds and nonmedicated feeds fortified with these drugs at the 1–50 ppm level. In addition, this method was used to confirm residues of monensin in a nonmedicated feed that was collected from a feed mill immediately after the production of a similar feed that was medicated with high levels of monensin.
Molecular Diagnosis of Microbial Contamination in Cosmetic and Pharmaceutical Products: A Review
Authors: Jimenez Luis
Published: February 2020

Molecular methodologies such as adenosine triphosphate (ATP) bioluminescence and polymerase chain reaction (PCR)-based assays provide rapid quality control analysis of cosmetic and pharmaceutical finished products and raw materials. Using a single enrichment broth for bacteria, yeast, and mold, ATP bioluminescence detected microbial contamination within 27 h. Samples were automatically lysed to release microbial ATP and light production was quantitated using the Celsis Optocomp. However, to maintain the detection time to within 27 h, different enrichment broths were required for neutralization of antimicrobial ingredients in finished products and to provide specific nutrients for growth optimization. To perform the PCR reaction, bacterial DNA was extracted using a Tris-EDTA–Tween 20–proteinase K buffer at 35°C while yeast and mold DNA were extracted using a Tris-EDTA–SDS buffer at 95°C. Extracted microbial DNA was added to Ready-To-Go PCR™ beads and specific DNA primers. The primers were targeted to amplify specific regions within Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhimurium, Burkholderia cepacia, Candida albicans, and Aspergillus niger. Furthermore, conserved bacterial ribosomal DNA sequences have also been used for sterility testing of samples. The results from these studies indicate that both ATP bioluminescence and PCR assays provide rapid, reliable, and cost effective methods for quality evaluation. This will ultimately result in faster product release and production optimization.
Comparison of the Reveal 20-Hour Method and the BAM Culture Method for the Detection of Escherichia coli O157:H7 in Selected Foods and Environmental Swabs: Collaborative Study
Authors: Bird Charles B , Hoerner Rebecca J , Restaino Lawrence ,   Collaborators:, Anderson G , Birbari W , Bodra L , Brookman D , Bryant D , Campbell C , Degraft-Hanson J , Fetviet D , Forde R , Goins D , Hajkowski S , Haley E , Holland R , Jones J , Joseph J M , Kallewaard N , Keckeissen J , Kirkbride T , Kusch S , Noel D , Nutsch A , Okolo C , Parks K , Raines D , Remes A , Roach V , Robbins R , Rodrick G , Shelef L , Theissen H , Vasavada P C , Wang T
Published: February 2020

Four different food types along with environmental swabs were analyzed by the Reveal for E. coli O157:H7 test (Reveal) and the Bacteriological Analytical Manual (BAM) culture method for the presence of Escherichia coli O157:H7. Twenty-seven laboratories representing academia and private industry in the United States and Canada participated. Sample types were inoculated with E. coli O157:H7 at 2 different levels. Of the 1095 samples and controls analyzed and confirmed, 459 were positive and 557 were negative by both methods. No statistical differences (p <0.05) were observed between the Reveal and BAM methods.
Determination of Manganese in Feedstuffs by Flow Injection Spectrophotometry Based on Rapid Formation of Permanganate at Room Temperature
Authors: Liu Jing-Fu , Feng Ying-Di , Jiang Gui-Bin
Published: February 2020

A simple and rapid flow injection spectrophotometric procedure was developed for determination of manganese. In the presence of pyrophosphate and acetate, manganese was immediately oxidized to permanganate by periodate at room temperature in slightly alkaline medium. Under optimized conditions, the determination was made with a sampling rate of 120/h, a linear range of 0–30 mg/L Mn(II), a detection limit (S/N = 3) of 0.08 mg/L, and a relative standard deviation of 0.6% (n = 11) at 10 mg/L Mn(II). The proposed method was used to determine manganese in trace mineral premixes and feedstuffs. Results agreed well with those obtained by the standard atomic absorption spectroscopy method.
Simultaneous Determination of Magnesium L-Ascorbyl-2-Phosphate and Kojic Acid in Cosmetic Bleaching Products by Using a Microbore Column and Ion-Pair Liquid Chromatography
Authors: Shih Ying
Published: February 2020

A rapid, sensitive, and reliable method was developed for the simultaneous determination of magnesium L-ascorbyl-2-phosphate (AS-PM) and kojic acid (KA), commonly using bleaching agents in cosmetic products. The method uses a prepacked C18 microbore column for ion-pair liquid chromatography with photodiode array detection. The eluant is 0.5mM tetrabutylammonium bromide and 0.05M phosphate buffer, pH 5, containing 5% methanol, at a flow rate of 70 μL/min. The determinations of AS-PM and KA were linear in the range of 0.5–1000 and 0.25–500 ng, respectively.The precision of the assay ranged from 0.31 to 2.19%, and the detection limits (signal-to-noise ratio = 3) were 0.04 and 0.02 ng for AS-PM and KA, respectively.
Determination of Aflatoxin B1 in Baby Food (Infant Formula) by Immunoaffinity Column Cleanup Liquid Chromatography with Postcolumn Bromination: Collaborative Study
Authors: Stroka Joerg , Anklam Elke , Joerissen Urban , Gilbert John ,   Collaborators:, Barmark A , Brera C , Dias B , Felgueiras I , Gardikis J , Macho L , Michelet Y J , Noutio K , Pittet A , Reutter M , Spanjer C M , Strassmeier E , Szymanski L , Worswick R
Published: February 2020

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for determination of aflatoxin B1 in a milk powder based infant formula at a possible future European regulatory limit (0.1 ng/g). The test portion was extracted with methanol–water (8 + 2 [v + v]), filtered, diluted with water, and applied to an immunoaffinity column. The column was washed with water to remove interfering compounds, and the purified aflatoxin B1 was eluted with methanol. The separation and determination of the aflatoxin B1 was performed by reversed-phase LC and detected by fluorescence after postcolumn derivatization (PCD) involving bromination. PCD was achieved with either pyridinum hydrobromide perbromide (PBPB) or an electrochemical (Kobra) cell by addition of bromide to the mobile phase. The baby food (infant formula) test samples, both spiked and naturally contaminated with aflatoxin B1, were sent to 14 laboratories in 13 different European countries. Test portions were spiked at levels of 0.1 and 0.2 ng/g for aflatoxin B1. Recoveries ranged from 101 to 92%. Based on results for spiked test samples (blind pairs at 2 levels) and naturally contaminated test samples (blind pairs at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 3.5 to 14%. The relative standard deviation for reproducibility (RSDR) ranged from 9 to 23%. Nine participants used PBPB derivatization, and 5 particpants used the Kobra cell. There was no evidence of method performance depending on the derivatization method used. The method showed acceptable within- and between-laboratory precision for baby food matrix, as evidenced by HORRAT values, at the target levels of determination for aflatoxin B1.
Proposed Phytic Acid Standard Including a Method for Its Analysis
Authors: Brooks Stephen P J , Oberleas Donald , Dawson Brian A , Belonje Bartholomeus , Lampi Brian J
Published: February 2020

A method is described that accurately and rapidly quantifies the free and total phosphorous content of a commercially available, purified, phytic acid preparation. This allows its use as a standard for phytic acid determinations in foods. The method involves a wet ashing step followed by phosphorous measurement with a 1-amino-2-naphthol-4-sulfonic acid-molybdate reagent in a microplate reader at 660 nm. The procedure can be performed in 3 h with as little as 50 mg sample.
Determination of Clethodim and Its Oxidation Metabolites in Crops by Liquid Chromatography with Confirmation by LC/MS
Authors: Ishimitsu Susumu , Kaihara Akiko , Yoshii Kimihiko , Tsumura Yukari , Nakamura Yumiko , Tonogai Yasuhide
Published: February 2020

A method was developed for determination of the herbicide clethodim (C0) and its oxidation metabolites clethodim sulfoxide (C1) and clethodim sulfone (C2) in agricultural products. Upon extraction, both C0 and C1 were oxidized to C2 by m-chloroperoxybenzoic acid, and C2 was determined by liquid chromatography (LC). The C2 peak was confirmed by liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization (ESI). Recoveries of C0 from radish, tomato, onion, sweet potato, kidney bean, carrot, cabbage, and lettuce ranged from 91 to 118% following fortification at 0.05–1.0 ppm. The detection limit of C2 in crops was 0.01 ppm (S/N > 3). The fortified samples of onion, sweet potato, kidney bean, and carrot were confirmed by LC/MS (ESI), and the peak of C2 was detected.
Performance of a Proposed Determinative Method for p-TSA in Rainbow Trout Fillet Tissue and Bridging the Proposed Method with a Method for Total Chloramine-T Residues in Rainbow Trout Fillet Tissue
Authors: Meinertz Jeffery R , Stehly Guy R , Gingerich William H , Greseth Shari L
Published: February 2020

Chloramine-T is an effective drug for controlling fish mortality caused by bacterial gill disease. As part of the data required for approval of chloramine-T use in aquaculture, depletion of the chloramine-T marker residue (para-toluenesulfonamide; p-TSA) from edible fillet tissue of fish must be characterized. Declaration of p-TSA as the marker residue for chloramine-T in rainbow trout was based on total residue depletion studies using a method that used time consuming and cumbersome techniques. A simple and robust method recently developed is being proposed as a determinative method for p-TSA in fish fillet tissue. The proposed determinative method was evaluated by comparing accuracy and precision data with U.S. Food and Drug Administration criteria and by bridging the method to the former method for chloramine-T residues. The method accuracy and precision fulfilled the criteria for determinative methods; accuracy was 92.6, 93.4, and 94.6% with samples fortified at 0.5X, 1X, and 2X the expected 1000 ng/g tolerance limit for p-TSA, respectively. Method precision with tissue containing incurred p-TSA at a nominal concentration of 1000 ng/g ranged from 0.80 to 8.4%. The proposed determinative method was successfully bridged with the former method. The concentrations of p-TSA developed with the proposed method were not statistically different at p < 0.05 from p-TSA concentrations developed with the former method.
Bioavailable Organochlorine Pesticides in a Semi-Arid Region of Eastern Oregon, USA, as Determined by Gas Chromatography with Electron-Capture Detection
Authors: Anderson Kim A , Johnson Eugene
Published: February 2020

A group of dissolved-bioavailable organochlorine (OC) pesticides and inorganic anions in water and total OC pesticides in sediments were measured in the Malheur Watershed, a semi-arid region in the western United States, over a 2-year period. OC pesticide levels were compared with those from a 1990 study of the lower section of the river, the most recent data available. After calculating the dissolved fraction from the 1990, study it seems that DDD and dieldrin levels have decreased in the water by 50–70%, while DDE and DDT have changed little. Although banned nearly 30 years ago, DDT is still persistent throughout the Malheur River basin/watershed because it was found in all water samples tested. All of the OC pesticides tested during the 2-year study are well below the criterion continuous concentration for aquatic community exposure as defined by the U.S. Environmental Protection Agency (EPA). OC pesticides appear to be decreasing, however, at lower Ontario there remains a human health risk (EPA Human Health Risk Water Quality Criteria) for DDT, because this criteria includes daily consumption of water and fish from the river. Overall, although the upper forest watershed sites have lower OC pesticide concentrations, they represent an important contribution to the total DDT load to this watershed, a source not previously acknowledged. The large increase in DDT and ΣDDT between the Ontario sites may indicate a possible historical point source of contamination or historical preferential deposition of contamination. Normalized sediment (ΣDDT/organic carbon) strongly correlates with dissolved water ΣDDT.
Multiresidue Determination of Pesticides in Drinking and Related Waters by Gas Chromatography/Mass Spectrometry after Solid-Phase Extraction: Interlaboratory Study
Authors: Hoof François van , Wiele Peter van , Bruchet Auguste , Schmitz Isabelle , Bobeldiji Ivana , Sacher Frank , Ventura Francesc , Marti Isabel , Monte Maria Helena Marecos Do , Costa Margarida Sa Da ,   Collaborators:, Alterova K , Barnier A , Hajslova J , Marti I , Martinez K , Planas C , Rivera J , Rörden O , Tejedor A , van der Kreeft R , Viana P , Werres F
Published: February 2020

As part of a project funded by the European Commission (EC) for the development and evaluation of multiresidue methods for analysis of drinking and related waters, 15 European laboratories evaluated a method using styrene–divinylbenzene copolymer solid-phase extraction followed by gas chromatography/mass spectrometry. The main aim of the study was to evaluate whether the method meets the requirements of EC Directive 98/83 in terms of accuracy, precision, and detection limit for 22 pesticides according to the following requirements: limit of detection, ≤0.025 μg/L; accuracy, expressed as recovery between 75 and 125%; and precision, expressed as repeatability relative standard deviation of the method of <12.5% and as reproducibility relative standard deviation of the method of <25%. Analyses for unknown concentrations were performed with fortified commercial bottled and tap waters. All laboratories were able to achieve detection limits of 0.01 μg/L for all pesticides except dimethoate and desisopropylatrazine (0.02 μg/L). The criteria for repeatability were met for all compounds except trifluralin, dimethoate, and lindane in bottled water and chlorpyrifos, dimethoate, and lindane in tap water. The criteria for reproducibility were met for all compounds except trifluralin, dimethoate, and lindane in bottled water and pendimethalin, chlorpyrifos, dimethoate, terbutryn, and lindane in tap water. In terms of accuracy, the method meets the requirements for all pesticides in both matrixes, except for lindane in bottled water and lindane and chlorpyrifos in tap water.
Fluorometric Determination of Ethanol in Liquor Samples by Flow-Injection Analysis Using an Immobilized Enzyme-Reactor Column with Packing Prepared by Coupling Alcohol Oxidase and Peroxidase onto Chitosan Beads
Authors: Taniai Tetsuyuki , Sukuragawa Akio , Okutani Tadao
Published: February 2020

A flow-injection system was developed for the determination of ethanol with an immobilized enzyme-reactor column. This system, which consisted of hand-made reactor columns packed with alcohol oxidase and horseradish peroxidase immobilized onto chitosan beads, and a fluorometric detector, was applied to the determination of ethanol in liquor samples. Under the recommended conditions, the ethanol, which was present in the pretreated samples, was converted to hydrogen peroxide when it was passed through the immobilized alcohol oxidase (AOD) column with 0.1 mol/dm3 phosphate buffer (pH 7.0). A sample can be analyzed with this system in <10 min. The calibration curve for ethanol was linear from 2.0 to 0.1 mg/dm3. The determination limit, which was defined by the difference between the sample peak and blank peak, was estimated to be 50 μg/dm3 for ethanol. Interferences from some substances present in actual liquor samples decreased the analytical response and activity of the immobilized AOD-reactor column, but they were removed by dilution and pretreatment with an octyldecylsilane cartridge.
Estimation of Measurement Uncertainty in Pesticide Residue Analysis
Authors: Alder Lutz , Korth Wolfagang , Patey Alan L , Schee Henk A van der , Schoeneweiss Siegmar
Published: February 2020

Proficiency test results from 5 countries involving 61 separate interlaboratory proficiency tests for pesticide residues were examined in this study. A total of 24 different matrixes and 869 relative standard deviations of the mean (or median) pesticide residue concentration were statistically evaluated in relation to the Horwitz function. The aim was to determine whether or not the concentration-dependent relationship described by Horwitz would hold for the much narrower range of chemicals and concentrations covered in routine pesticide residue analysis. Although for fatty (animal-derived) matrixes the variability increased as the concentration decreased in line with the Horwitz equation, the between-laboratories relative standard deviations for nonfatty matrixes (fruit, vegetables, and grain) remained at 25% over the entire concentration range of 1 μg/kg to 10 mg/kg for the pesticides studied. Given these findings, the Horwitz equation remains valid for calculating uncertainties involving pesticide residues in fatty matrixes. However, for pesticide residue analyses involving nonfatty matrixes, a constant relative standard deviation of 25% is more appropriate for calculating uncertainties, particularly when a reported result is assessed against a regulatory limit.
Integrated Enzyme-Linked Immunosorbent Assay Screening System for Amnesic, Neurotoxic, Diarrhetic, and Paralytic Shellfish Poisoning Toxins Found in New Zealand
Authors: Garthwaite Ian , Ross Kathryn M , Miles Christopher O , Briggs Lyn R , Towers Neale R , Borrell Teresa , Busby Phil
Published: February 2020

Enzyme-linked immunosorbent assays (ELISAs) were developed for amnesic, neurotoxic, and diarrhetic shellfish poisoning (ASP, NSP, and DSP) toxins and for yessotoxin. These assays, along with a commercially available paralytic shellfish poisoning (PSP) ELISA, were used to test the feasibility of an ELISA-based screening system. It was concluded that such a system to identify suspect shellfish samples, for subsequent analysis by methods approved by international regulatory authorities, is feasible. The assays had sufficient sensitivity and can be used on simple shellfish extracts. Alcohol extraction gave good recovery of all toxin groups. The ease of ELISAs permits the ready expansion of the system to screen for other toxins, as new ELISAs become available.
Simultaneous Determination of Losartan and Hydrochlorothiazide in Combined Dosage Forms by First-Derivative Spectroscopy and High-Performance Thin-Layer Chromatography
Authors: Shah Shailesh A , Rathod Ishwarsinh S , Suhagia Bhanubhai N , Savale Shrinivas S , Patel Jignesh B
Published: February 2020

Losartan (LST) is the first orally active nonpeptide angiotensin-II receptor antagonist with an improved safety and tolerability profile. It is prescribed alone or in combination with hydrochlorothiazide (HCTZ) for the treatment of moderate-to-severe hypertension. This paper describes the development of 2 methods that use different techniques, first-derivative spectroscopy and high-performance thin-layer chromatography (HPTLC), to determine LST and HCTZ in the presence of each other. LST and HCTZ in combined preparations were quantitated by using the first-derivative responses at 271.6 nm for LST and 335.0 nm for HCTZ in spectra of their solutions in water. The linearity ranges are 30–70 μg/mL for LST and 7.5–17.5 μg/mL for HCTZ with correlation coefficients of 0.9998 and 0.9997, respectively. In the HPTLC method, a mobile phase of chloroform–methanol–acetone–formic acid (7.5 + 1.5 + 0.5 + 0.03, v/v) and a prewashed Silica Gel G60 F254 TLC plate as the stationary phase were used to resolve LST and HCTZ in a mixture. Two well-separated and sharp peaks for LST and HCTZ were obtained at Rf values of 0.61 ± 0.02 and 0.41 ± 0.02, respectively. LST and HCTZ were quantitated at 254.0 nm. The linearity ranges obtained for the HPTLC method are 400–1200 and 100–300 ng/spot with corresponding correlation coefficients of 0.9944 and 0.9979, for LST and HCTZ, respectively. Both methods were validated, and the results were compared statistically. They were found to be accurate, specific, and reproducible. The methods were successfully applied to the estimation of LST and HCTZ in combined tablet formulations.
Selective Liquid Chromatographic Method for Determination of Fluoxetine in Plasma
Authors: Zarghi Afshin , Kebriaeezadeh Abbas , Ahmadkhaniha Reza , Akhgari Maryam , Rastkari Nooshin
Published: February 2020

A selective and sensitive liquid chromatographic method was developed for the determination of fluoxetine (FLU) in plasma. FLU was isolated from plasma by liquid–liquid extraction. The chromatographic separation was performed on an analytical 250 × 3.9 mm id Novapak C18 column (4 μm particle size) with an isocratic mobile phase consisting of phosphate buffer–acetonitrile–methanol–triethylamine (58 + 30 + 10 + 2, v/v) adjusted to pH 7. Using UV detection at 226 nm, the detection limit for FLU in plasma was 3 ng/mL. No interferences were found with tricyclic antidepressant drugs, which allows this method to be used in clinical studies. The calibration curve was linear over the concentration range of 10–200 ng/mL. The average recovery was about 80% for plasma. The inter- and intraday assay coefficients of variation were <8%.
Post Process Product Control of Rendering Plant Sterilization Conditions by ELISA
Authors: Holst Christoph von , Unglaub Wolfgang , Anklam Elke
Published: February 2020

Experiments were conducted in a laboratory autoclave and in a commercial rendering plant to set a limit for the R-value of an enzyme-linked immunosorbent assay (ELISA) to prove that animal meal had been sufficiently heat-treated. The immunoassay method is currently the only technique used to check for appropriate sterilization of animal meal. The results of these experiments were statistically assessed using operation characteristic curves and confirmed that insufficiently heat-treated animal meal has an R-value > 2. Results of the trials also demonstrated that the main parameters of sterilization, temperature, and duration strongy influence the R-value, thus indicating that deviation from the target sterilization conditions is verifiable by the ELISA method.
Levels of Seven PCBs Used as Markers of Dioxin in Commercial Pork Meat in Spain
Authors: López-Leitón Teresa J López y , Piñeiro María E Alvarez , Yusty María A Lage , Daviña José L Cortizo
Published: February 2020

The levels of 7 PCBs used as markers of dioxin in 62 pork meat samples (head, loin, and dewlap) were determined by supercritical fluid extraction and gas chromatography with electron capture detection. Analytical limits of detection for the individual congeners ranged from 0.048 to 0.2 ng/g dry wt. PCB congeners 153 and 180 were detected in all samples. Among congeners in general, PCB 52, 101, and 153 were the most abundant. There was a linear relationship with a good correlation between PCB 101 and PCB 52.
Determination of Rendering Plant Sterilization Conditions Using a Commercially Available ELISA Test Kit Developed for Detection of Cooked Beef
Authors: Pallaroni Lea , Björklund Erland , Holst Christoph von , Unglaub Wolfgang
Published: February 2020

A commercially available enzyme-linked immunosorbent assay (ELISA) test kit developed for detection of cooked beef in meat samples was used to determine appropriate heat treatment of rendered materials. An improved extraction procedure increased the absolute difference in R-values between 2 rendered materials treated under different conditions (average temperature 129 and 134°C, respectively). To evaluate the influence of the main sterilization parameters on ELISA results, a factorial design approach was used. The parameters investigated were temperature, time, particle size, and meat composition. Lean meat samples containing beef and pork were sterilized under strictly controlled conditions in a laboratory autoclave. The experiments demonstrated that the R-values obtained with the ELISA test kit for beef are strongly influenced by temperature and time, whereas particle size has a minor influence. The proportion of bovine material did not have any impact on R-values. Autoclave-processed lean meat samples were analyzed by using an ELISA test kit for pork, which was validated in a collaborative trial. The ELISA test kit for pork proved to be more sensitive for the investigated parameters, thus verifying and extending previous investigations.
Spectrophotometric Determination of Ziram in a Commercial Sample and Wheat by Extraction of Its Copper Dimethyldithiocarbamate Complex into Molten Naphthalene
Authors: Malik Ashok Kumar , Rao Avasarla L J
Published: February 2020

A method was developed for the determination of zinc(II) dimethyldithiocarbamate by converting it into the copper(II) dithiocarbamate complex, which is then extracted into molten naphthalene. The absorbance is measured at 430 nm versus a reagent blank. Beer's law is obeyed for concentrations of 0.63 × 10−3 to 17.2 × 10−3 g/L in the final solution. The method is sensitive and was applied to the determination of ziram in a commercial sample and in wheat grain.
Employment of Peak Area as Instrumental Datum for Improving the Voltammetric Quantitative Analysis of Heavy Metals in Fresh and Sea Water in the Presence of Surfactants
Authors: Locatelli Clinio
Published: February 2020

Peak area instead of peak height is used for the simultaneous determination of Cu(II), Pb(II), Cd(II), and Zn(II) in fresh and sea water in the presence of anionic and cationic surfactants by differential pulse anodic stripping voltammetry. These species, if present, tend to make more irreversible the electrodic process of the metals. Because the employment of peak area for species having irreversible electrodic processes permits limits of detection about one or 2 orders of magnitude lower, this work shows the possibility of determining heavy metals at ultratrace level concentrations in the presence of surfactants, compounds which are always present in natural waters. The precision and accuracy of the analytical method were checked by the analysis of the standard reference materials (SRM) Fresh Water NIST-SRM 1643d, Sea Water BCR-CRM 403, and Estuarine Water BCR-CRM 505. The former, expressed as relative standard deviation (sr), and the latter, expressed as relative error (e), were satisfactory, being in all cases lower than 5%. The analytical procedure has been applied to fresh and sea water sampled in the Po river mouth area (Italy).
Enhanced Recovery of Salmonella from Apple Cider and Apple Juice with Universal Preenrichment Broth
Authors: Hammack Thomas S , Johnson Mildred L , Jacobson Andrew P , Andrews Wallace H
Published: February 2020

A comparison was made of the relative efficiencies of Universal Preenrichment (UP) broth and lactose broth for the recovery of a variety of Salmonella serovars from pasteurized and unpasteurized apple cider and pasteurized apple juice. Bulk portions of juice were contaminated with single Salmonella serovars at high and low levels of 0.4 and 0.04 CFU/mL, respectively. The juice was aged for a minimum of 5 days at 2–5°C. On the day analysis was initiated, each of 20 test portions (25 mL) of the contaminated juice was preenriched in UP broth and in lactose broth. The Bacteriological Analytical Manual Salmonella culture method was followed thereafter. For pasteurized apple cider, UP broth recovered significantly (p < 0.05) more Salmonella-positive test portions than did lactose broth (112 and 75, respectively). For unpasteurized apple cider, UP broth recovered significantly more Salmonella-positive test portions than did lactose broth (326 and 221, respectively). For pasteurized apple juice, UP broth recovered more Salmonella-positive test portions than did lactose broth (93 and 81, respectively). However, this difference was not statistically significant. These results indicate that UP broth should replace lactose broth for the analysis of pasteurized and unpasteurized apple cider and pasteurized apple juice.
Determination of Nalidixic Acid by Fluorometry with Sodium Borohydride and Hydrogen Peroxide
Authors: Wang Mei-Lin , Chen Sheng-Chih , Lien Jin-Cherng , Kuo Sheng-Chu
Published: February 2020

A simple and sensitive fluorometric method for the determination of nalidixic acid was established by using 0.75M sodium borohydride and 7.5% hydrogen peroxide solution as fluorogenic reagents. Analyte concentrations of 0.0232–11.6 pg/mL could be determined with high precision and accuracy by the method. A relative standard deviation of 1.75% was obtained for a nalidixic acid concentration of 0.232 pg/mL. The method was satisfactorily applied to the determination of nalidixic acid in human serum, fish muscle, and chicken muscle, and the calibration curves were linear from 0.23 to 58.00 pg/mL, from 9.28 to 32.48 mg/kg, and from 4.64 to 23.20 mg/kg, respectively. The specificity of the reaction is also discussed.
Real-Time Quantitative Polymerase Chain Reaction Methods for Four Genetically Modified Maize Varieties and Maize DNA Content in Food
Authors: Brodmann Peter D , Ilg Evelyn C , Berthoud Hélène , Herrmann André
Published: February 2020

Quantitative detection methods are needed for enforcement of the recently introduced labeling threshold for genetically modified organisms (GMOs) in food ingredients. This labeling threshold, which is set to 1% in the European Union and Switzerland, must be applied to all approved GMOs. Four different varieties of maize are approved in the European Union: the insect-resistant Bt176 maize (Maximizer), Bt11 maize, Mon810 (YieldGard) maize, and the herbicide-tolerant T25 (Liberty Link™) maize. Because the labeling must be considered individually for each ingredient, a quantitation system for the endogenous maize content is needed in addition to the GMO-specific detection systems. Quantitative real-time polymerase chain reaction detection methods were developed for the 4 approved genetically modified maize varieties and for an endogenous maize (invertase) gene system.
Measurement of cis and trans Isomers of Vitamin K1 in Rat Tissues by Liquid Chromatography with a C30 Column
Authors: Cook Kathleen K , Grundel Erich , Jenkins Mamie Y , Mitchell Geraldine V
Published: February 2020

The purpose of this study was to validate a method for measuring vitamin K isomers in rat tissues by liquid chromatography (LC) with fluorescence detection after simple solvent extraction. This method uses separation on a C30 column, followed by zinc reduction and fluorescence measurement (243 nm, excitation; 430 nm, emission) to detect and quantitate vitamin K isomers. We were able to separate cis- and trans-vitamin K1 in methylene chloride extracts of homogenized rat livers and in hexane extracts of rat plasma. Tissue extracts were evaporated and rediluted with tetrahydrofuran–methanol (1 + 1) or methanol before being injected under isocratic conditions onto the LC column. Liver tissue of Fischer 344 rats fed a vitamin K1-containing diet ad libitum contained approximately 20 and 60 ng/g cis- and trans-vitamin K1, respectively. Mean recoveries of vitamin K1 isomers from spiked liver were 92 ± 11% for cis-vitamin K1 and 106 ± 5% for trans-vitamin K1. We recovered 96 ± 8% of trans-vitamin K1 added at 1, 3, and 6 ng/mL to plasma (containing an endogenous level of 4 ng/g) from the same rats; we recovered 112 ± 5% when trans-vitamin K1 was added to human serum (National Institute of Standards and Technology Standard Reference Material 968C). This direct method shows significant potential for the selective measurement of vitamin K1 isomers in tissues.
Determination of Sulfonamide Residues in Eggs by Liquid Chromatography
Authors: Furusawa Naoto
Published: February 2020

A method was developed for determining residual sulfonamide antibacterials such as sulfamethazine (SMZ), sulfamonomethoxine (SMM), sulfadimethoxine (SDM), and sulfaquinoxaline (SQ) in eggs using liquid chromatography with a photodiode array detector. The spiked and blank samples were cleaned up by using an Ultrafree®-MC/PL centrifugal ultrafiltration unit. A Mightysil® RP-4 GP column and a mobile phase of 28% (v/v) ethanol–H2O with a photodiode array detector were used for the determination. Average recoveries from eggs spiked with each drug at 0.1, 0.2, 0.4, and 1.0 ppm were ≥80.9%, with relative standard deviations between 1.3 and 4.7%. The limits of quantitation were 0.060 ppm for SMZ, 0.045 for SMM, 0.044 for SDM, and 0.093 for SQ. The analysis of one sample required <30 min and <5 mL ethanol as solvent.