bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous Determination of Emamectin and Ivermectin Residues in Atlantic Salmon Muscle by Liquid Chromatography with Fluorescence Detection
Authors: Riet Jeffrey M van de , Brothers Natalie N , Pearce Johanna N , Burns B Garth
Published: February 2020

A liquid chromatographic (LC) method for determining residues of the antiparasitic drugs emamectin (EMA) and ivermectin (IVR) in fish tissues has been developed. EMA and IVR residues are extracted with acetonitrile and cleaned up on a C18 solid-phase extraction column. Extracts are derivatized with 1-methylimidazole and trifluoroacetic anhydride and the components are determined by LC on a C18 reversed-phase column with fluorescence detection (excitation: 365 nm, emission: 470 nm). The mobile phase is 94% acetonitrile–water run isocratically. Calibration curves were linear between 1 and 32 ng injected for both EMA and IVR. The limit of detection for both analytes was 0.5 ng/g, with a limit of quantitation of 1.5 ng/g. Recoveries of EMA and IVR added to salmon muscle averaged 96 ± 9% and 86 ± 6%, respectively, at levels between 5 and 80 ng/g. The percent relative standard deviation for the described method was less than 7% over the range of concentrations studied. The operational errors, interferences, and recoveries for fortified samples compare favorably with an established IVR method. The recommended method is simple, rapid, and specific for monitoring residues of EMA and IVR in Atlantic salmon muscle.
Determination of Salicylate in Blood Serum by Flow Injection with Immobilized Salicylate Hydroxylase
Authors: Vila Marta M D C , Tubino Matthieu , Neto Graciliano de Oliveira
Published: February 2020

A flow injection (FI) enzymatic system, based on the use of immobilized salicylate hydroxylase in glass beads, was developed for the determination of salicylate. Salicylate hydroxylase and nicotinamide adenine dinucleotide (NADH) are used to convert salicylate to catechol. The reaction of catechol with 4-aminophenol at high pH yields a colored product which is detected spectrophotometrically at 565 nm. Ten samples of human serum containing from 5.0 × 10−4 to 5.0 × 10−3 mol/L added salicylate were analyzed and the recovery was determined. Eight additional serum samples containing salicylate were analyzed by the Trinder test and the proposed method. The results obtained with the 2 methods showed good agreement by the statistical Student's t-test. The relative precision of the method is about 3.4% (RSD of the mean recovery). Considering the lowest concentration analyzed, the quantitative limit of detection is about 0.2 × 10−5 mol/L (3 × SD). The volume of the sample used was 150 μL. The proposed method was also used to analyze medicines containing acetylsalicylic acid. The results were statistically compared with those obtained through the U.S. Pharmacopoeia procedure and showed excellent agreement.
Environmental Monitoring of Pesticides by Immunoanalytical Techniques: Validation, Current Status, and Future Perspectives
Authors: Lee Nanju A , Kennedy Ivan R
Published: February 2020

Reliable monitoring technology is an essential component of effective regulation and risk management of environmental contaminants such as pesticides. Most environmental monitoring and analysis is currently conducted using instrumental techniques such as gas–liquid chromatography (GLC) and liquid chromatography (LC). Immunoanalysis provides powerful monitoring techniques that have emerged in the last 3 decades. This paper shows they can deliver rapid, accurate, and relatively inexpensive analysis with high throughput and that have the capability to be field oriented. The technique is versatile in application and can be formatted to suit different purposes such as quantitative analysis or simple “yes/no” tests that are field-portable. While there is a range of opinion on the merits of immunoassays as an analytical tool for pesticides, we suggest that this technology is best considered as complementary to GLC and LC, extending the range of capability for field monitoring. Supporting this view, an increasing number of successful applications of immunoassays to monitoring have been reported in recent years. We also report here the implications of recent developments in the field of immunodiagnostics and their application to monitoring of environmental contaminants. We emphasise that, together with adequate validation by instrumental techniques, immunoassays provide monitoring services yielding realistic and comprehensive data for risk management, allowing decisions on appropriate action by various authorities to be made.
Determination of Fat in Raw and Processed Milks by the Gerber Method: Collaborative Study
Authors: Kleyn Dick H , Lynch Joanna M , Barbano David M , Bloom M Jeffrey , Mitchell Martin W ,   Collaborators:, Cooper L S , Cusak E , Fick M , Hanks T , Hesen M K , Johnson J , Kleyn D H , Mercer F , Monahan D , Peat B , Petit M
Published: February 2020

The Gerber method is used worldwide as a simple and rapid method for determining fat in raw and processed milks. However, the volume of the test portion used in the method has not been internationally agreed upon. A collaborative study was conducted to evaluate performance of the Gerber method using either a weighed test portion (11.13 g) or by a 10.77 mL test portion delivered by pipet. For each method, laboratories received 10 test samples: 5 raw and 5 pasteurized homogenized milks, 2 of which were blind duplicate pairs. Eleven and 10 laboratories participated in the evaluation of aliquot addition by weight and pipet, respectively. Mojonnier ether extraction (Method 989.05) was used as the reference method. Interlaboratory study statistics were similar between methods of test portion addition and between raw and processed materials; therefore, summary interlaboratory study statistics were pooled. The fat content of milk samples ranged from 0.96 to 5.48%. Absolute reproducibility and repeatability were not affected by fat level, and pooled statistical performance (invalid and outlier data removed) was (g fat/100 g milk) sr = 0.026, sR = 0.047, r = 0.074, and R = 0.132. Relative standard deviations increased with decreasing fat content, and were summarized by fat level: 1–2% fat milk, mean = 1.437, RSDr = 1.809%, RSDR = 3.271%; 2–6% fat milk, mean = 4.156, RSDr = 0.626%, RSDR = 1.131%. Compared with ether extraction, test results by the Gerber method were slightly lower (0.02% fat) using a weighed test portion and significantly lower (0.06% fat) using a 10.77 mL volume addition by pipet. A trend toward underestimating fat content at lower fat concentrations (1–2% fat) was observed with the weighed test portion but not when a pipet was used. The Associate Referee recommends that the Gerber method using a weighed test portion be adopted as First Action with applicability limited to whole milk.
On-Line Complexation/Preconcentration System for the Determination of Lead in Wine by Inductively Coupled Plasma–Atomic Emission Spectrometry with Ultrasonic Nebulization
Authors: Wuilloud Rodolfo G , González Alfredo H , Marchevsky Eduardo J , Olsina Roberto A , Martinez Luis D
Published: February 2020

An on-line lead preconcentration and determination system implemented with inductively coupled plasma–atomic emission spectrometry (ICP–AES) with ultrasonic nebulization (USN) in association with flow injection was studied. For the preconcentration of lead, a Pb–quinolin–8–ol complex was formed on-line at pH 6.8 and retained on Amberlite XAD–16 resin. The lead was removed from the microcolumn by countercurrent elution with nitric acid. A total enhancement factor of 225 was obtained with respect to ICP–AES with pneumatic nebulization (15.0 for USN and 15.0 for the column). The detection limit for Pb for the preconcentration of a 10 mL wine sample was 0.15 μg/L. The precision for 10 replicate determinations at a Pb level of 25 μg/L was a relative standard deviation of 2.5%, calculated from the peak heights obtained. The calibration graph obtained by using the preconcentration system for lead was linear with a correlation coefficient of 0.9995 for levels near the detection limit up to ≥ 1000 μg/L. The method was successfully applied to the determination of lead in wine samples.
Identification of Commercial Fish Species Belonging to the Orders Pleuronectiformes and Gadiformes: Library of Isoelectric Focusing Patterns
Authors: Tepedino Valentina , Berrini Anna , Borromeo Vitaliano , Gaggioli Daniela , Cantoni Carlo , Manzoni Paolo , Secchi Camillo
Published: February 2020

Isoelectric focusing in polyacrylamide gel was used to establish an identification archive of fish species belonging to the orders Pleuronectiformes, or flat fish, and Gadiformes, or gadoid fish. The 2 orders include species of different commercial value and interest that are frequently requested in European fish markets, but are susceptible to substitution either because they are morphologically similar or because they arrive on the markets already filleted or sliced. The sarcoplasmic protein profiles are species-specific and reproducible. The use of densitometry and image analysis coupled with a simple computer program overcomes the subjective evaluation of the patterns, making it possible to identify species correctly.
Simultaneous Densitometric Determination of Indomethacin and Its Degradation Products, 4-Chlorobenzoic Acid and 5-Methoxy-2-Methyl-3-Indoleacetic Acid, in Pharmaceutical Preparations
Authors: Krzek Jan , Starek Magorzata
Published: February 2020

A densitometric method was developed for the identification and determination of indomethacin and its degradation products, 4-chlorobenzoic acid and 5-methoxy-2-methyl-3-indoleacetic acid, in pharmaceuticals. To separate these compounds, silica gel-coated thin-layer chromatography plates and the following mobile phase were used: 2-propanol–25% ammonia–water (8 + 1 + 1, v/v). UV densitometric measurements were made by comparing the absorption spectra and Rf values of appropriate standards with the pharmaceutical preparations examined. The conditions for separation were established and a low detection limit was obtained. Average recoveries were 100.69, 90.09, and 91.17% for indomethacin, 4-chlorobeznzoic acid, and 5-methoxy-2-methyl-3-indoleacetic acid, respectively.
Development and Validation of a Chiral Liquid Chromatographic Method for the Determination of Atenolol and Metoprolol Enantiomers in Tablet Preparations
Authors: Singh Anil K , Kedor-Hackmann Erika R M , Santoro Maria Inês R M
Published: February 2020

Atenolol (AT) and metoprolol (MT) are predominantly used in the treatment of angina pectoris, certain arrhythmias, systemic hypertension, and several other cardiovascular disorders. Both compounds are produced commercially in the racemic form, although the S-form is responsible for the desired biological effect. This paper describes a simple, rapid, precise, and accurate method for separating the enantiomers of AT and MT. AT isomers are separated by using a Chiralcel OD® column (250 × 4.6 mm, 10 μm), hexane–ethanol–diethylamine–acetic acid (60 + 40 + 0.2 + 0.2, v/v/v/v) as the mobile phase, and a flow rate of 1.0 mL/min. MT isomers are separated by using a mobile phase with the same components in the following proportions (40 + 60 + 0.2 + 0.2, v/v/v/v) and a flow rate of 0.8 mL/min. Ultraviolet detection was at 276 nm for both analytes. The coefficients of variation (CVs) and average recoveries (ARs) for the R-enantiomers in samples A, B, C, D, and E were 1.15 and 101.06%, 0.74 and 99.25%, 1.05 and 102.57%, 0.84 and 101.57%, and 0.86 and 98.62%, respectively. The CVs and ARs for the S-enantiomers in samples A, B, C, D, and E were 1.33 and 98.87%, 0.99 and 100.76%, 1.17 and 101.69%, 1.26 and 100.39%, and 1.40 and 99.39%, respectively. The standard curves of R-AT, S-AT, R-MT, and S-MT showed good linearity over the concentration range studied with correlation coefficients of 0.9991, 0.998, 0.9988, and 0.999, respectively.
Production and Use of BCR Reference Materials for Quality Assurance in Environmental Analysis: An Update
Authors: Quevauviller Philippe
Published: February 2020

Reference materials represent an invaluable tool for analytical quality control. Certified Reference Materials (CRMs) are used for the validation of methods, whereas various types of (uncertified) Reference Materials (RMs) are used for routine quality control (establishment of control charts) and interlaboratory testing (e.g., proficiency testing). This paper provides background information on the production and use of environmental RMs and describes recent CRMs produced by the BCR (European Commission) for quality assurance in environmental analysis.
Validation of PCR Methods for Quantitation of Genetically Modified Plants in Food
Authors: Hübner Philipp , Waiblinger Hans-Ullrich , Pietsch Klaus , Brodmann Peter
Published: February 2020

For enforcement of the recently introduced labeling threshold for genetically modified organisms (GMOs) in food ingredients, quantitative detection methods such as quantitative competitive (QC-PCR) and real-time PCR are applied by official food control laboratories. The experiences of 3 European food control laboratories in validating such methods were compared to describe realistic performance characteristics of quantitative PCR detection methods. The limit of quantitation (LOQ) of GMO-specific, real-time PCR was experimentally determined to reach 30–50 target molecules, which is close to theoretical prediction. Starting PCR with 200 ng genomic plant DNA, the LOQ depends primarily on the genome size of the target plant and ranges from 0.02% for rice to 0.7% for wheat. The precision of quantitative PCR detection methods, expressed as relative standard deviation (RSD), varied from 10 to 30%. Using Bt176 corn containing test samples and applying Bt176 specific QC-PCR, mean values deviated from true values by −7 to 18%, with an average of 2 ± 10%. Ruggedness of real-time PCR detection methods was assessed in an interlaboratory study analyzing commercial, homogeneous food samples. Roundup Ready soybean DNA contents were determined in the range of 0.3 to 36%, relative to soybean DNA, with RSDs of about 25%. Taking the precision of quantitative PCR detection methods into account, suitable sample plans and sample sizes for GMO analysis are suggested. Because quantitative GMO detection methods measure GMO contents of samples in relation to reference material (calibrants), high priority must be given to international agreements and standardization on certified reference materials.
Trace Elements in Western Canadian Hard Red Spring Wheat (Triticum aestivum L.): Levels and Quality Assurance
Authors: Gawalko Eugene J , Garrett Robert G , Nowicki Thomas W
Published: February 2020

A monitoring program was conducted for trace elements in Western Canadian Hard Red Spring wheat (Triticum aestivum L.). Samples were selected from harvest survey samples submitted by producers from crop districts in Manitoba, Saskatchewan, and Alberta for 1996, 1997, and 1998 crops. The analytical quality control measures used in these surveys are described along with the results for Cd, Cu, Fe, Mn, Se, and Zn. Accuracy and precision for the analyses fell within the acceptable control limits. Year-to-year variations in grain chemistry were small for Cd, Mn, Se, and Zn, but Cu and Fe contents showed 12 and 9% decreases, respectively, over the 3 years. The overall variability for the plant-essential trace elements—Cu, Fe, Mn, and Zn—was low compared with that for Cd and Se. The spatial variation in crop chemistry across the Canadian Prairie wheat-producing region was greater than the year-to-year variations. Soil properties were major factors in controlling Cd and Se levels in grain.
Cadmium and Other Metals in Swedish Wheat and Rye Flours: Longitudinal Study, 1983–1997
Authors: Jorhem Lars , Sundström Birgitta , Engman Joakim
Published: February 2020

Wheat flour (sifted), wheat bran, and rye flour were sampled annually in several different areas in Sweden for 15 consecutive years (1983–1997) for a total of 105, 90, and 30 samples, respectively. These samples were analyzed for their content of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn by atomic absorption spectrophotometry with background correction after dry ashing at 450° C. As part of the quality control procedures, an in-house reference material was analyzed in parallel to the samples to ensure reliability of the results. In addition, a certified reference material was analyzed to monitor accuracy of the results. The Cd level in wheat and rye flours (mean 0.029 and 0.017 mg/kg dry wt, respectively) correlated significantly with time (p < 0.05) in 2 phases, tending to increase during the first half of the period and decrease during the latter half. In wheat bran, Cd (mean 0.15 mg/kg) levels did not correlate significantly with time. In wheat flour, Cu, Mn, and Zn (means 1.7, 6.2, and 7.6 mg/kg, respectively) showed a significant linear increase (p < 0.05) in concentration over time. In rye flour, the levels of Cu, Fe, Mn, and Zn (means 3.8, 36, 30, and 28 mg/kg, respectively) all decreased significantly (p < 0.05) over time. Similarly, in wheat bran Cu (mean 14 mg/kg) increased and Pb (mean 0.027 mg/kg) decreased significantly (p < 0.05) over time, whereas Ni and Zn showed a significant curved correlation with time and peaked at about the middle of the measurement period.
Evaluation of the Use of Liquid Dishwashing Compounds To Control Bacteria in Kitchen Sponges
Authors: Nielsen Peter , Brumbaugh Ernie , Kananen Lafonna
Published: February 2020

A test procedure for evaluating the effect of adding commercial liquid hand dishwashing detergents to kitchen sponges to control microbial growth is described. Claims for this type of application are being made on dishwashing detergents throughout the world. In this evaluation, commercially available kitchen sponges were stripped of antimicrobial compounds. Sponges were then inoculated with a pool of 7 microorganisms which consisted of Gram positives, Gram negatives, and yeast. Inoculated sponges were treated with the detergent as recommended by the manufacturer and allowed to incubate for 16 h at ambient temperature. Surviving microorganisms were then quantitated using either the spiral or pour plate method. Tests were run using both clean sponges and sponges soiled with 0.5% nonfat dry milk (NFDM). Untreated sponges showed stasis or slightly increased bacterial populations after the incubation period in the absence of NFDM. Significant increases of up to 3 log cfu/mL were observed for untreated sponges when soiled with NFDM. Statistically significant reductions were observed for clean sponges (99.8–99.9998%) and sponges soiled with NFDM (87.6–99.9%) when detergents making “antibacterial sponge” claims were added to the inoculated sponges. Statistically significant differences between detergents making “antibacterial sponge” claims were also observed.
Dietary Exposure of Thais to Pesticides During 1989–1996
Authors: Vongbuddhapitak Amara , Atisook Kanokporn , Thoophom Gobthong , Sungwaranond Boonpai , Lertreungdej Yuwadee , Suntudrob Jitpaka , Kaewklapanyachareon Ladda
Published: February 2020

To monitor the exposure of the Thai to pesticide residues in foods, the intake of pesticides based on the total diet approach has been studied in Thailand continually since 1989. Food items were chosen and their proportions of daily consumption were calculated from the national food consumption survey conducted by the Department of Health in 1986. Seventy-seven items of food including drinking water were classified into 12 groups according to their sources of contamination and the analytical methods used. Shopping lists and standard procedures for collecting samples and cooking were developed. Twelve food composites from each of the 4 regions were analyzed for nearly 100 pesticides. All analyses used multiresidue analytical methods, and the total daily dietary intakes of pesticide residues were estimated from the average amount of food consumed by Thais. Among 24 pesticides found in the 8 year study, DDT, dimethoate, methamidophos, and parathion methyl were found every year. However, dietary intakes of all pesticides were far below the established acceptable daily intake. In 1999, the study methodology was redesigned to accommodate the new national food consumption survey data.
Qualitative and Quantitative Reversed-Phase Liquid Chromatography of a New Bisisoxazolylnaphthoquinone
Authors: Ferreyra Carola F , Ortiz Cristina S , Bertorello María M de
Published: February 2020

The main objective of this study was to develop and test the applicability of a sensitive, accurate, and precise liquid chromatographic (LC) method for evaluating the stability characteristics of a new bisisoxazolylnaphthoquinone, 2-(3,5-dimethyl-4-isoxazolylamino)-N-(3,5-dimethyl-4-isoxazolyl)-1,4-naphthoquinone-4-imine compound 1. The method was shown to be selective and stability-indicating. Isocratic elution with a mobile phase of methanol–water (75 + 25, v/v) on a reversed-phase column with UV detection at ambient temperature completely resolved compound 1 from its degradation products. The LC system was calibrated by plotting peak responses versus known concentrations of a reference standard by using an internal standardization procedure. Complete elution occurred after 12 min with a peak symmetry factor of 0.95 for the drug peak. The kinetic degradation of compound 1 was studied over a pH range of 0.88–14.00 to determine the kinetic parameters involved in its decomposition path in aqueous solution.
Testing Antimicrobials Against Biofilm Bacteria
Authors: Hamilton Martin Alva
Published: February 2020

Standard laboratory methods are needed to assess the efficacy of antimicrobial agents that are applied to biofilm bacteria. Existing standard suspension tests and dried surface tests show much greater efficacy than antimicrobial agents applied to biofilms. The greater resistance of biofilm bacteria to antimicrobial agents can be attributed to a number of interacting factors, including reaction and diffusion processes that limit an agent's accessibility to bacteria, phenotypic changes in biofilm bacteria caused by stress, and adaptation of the bacteria. Because biofilm systems are so diverse, a variety of new biofilm tests with features that differ in important ways from existing tests will ultimately be required. For example, the biofilm test apparatus may include a pump and a continuous flow stirred tank reactor. This report provides an overview of biofilm testing and suggests a strategy for creating standard test methods.
Determination of WR-1065 and WR-33278 by Liquid Chromatography with Electrochemical Detection: PVM 1:2002
Authors: Pendergrass James A , Srinivasan Venkataraman , Kumar K Sree , Jackson William E , Seed Thomas M , Pendergrass James A , Kleinman Wayne A
Published: February 2020

A liquid chromatographic method using electrochemical detection is presented for measuring the thiol WR-1065 [2-(3-aminopropylamino) ethanethiol] and its symmetrical disulfide WR-33278 [NH2(CH2)3NHCH2CH2S]2. WR-1065 is the active, radioprotective drug derived from the phosphorothioate pro-drug WR-2721 (amifostine). External standard curves for both compounds were linear over the range of 40-200 pmol injected (r2 = 0.999 and 0.996 for the thiol and disulfide, respectively). The detection and quantitation limits for WR-1065 were 9 and 18 pmol, respectively, whereas the corresponding values for WR-33278 were 30 and 59 pmol, respectively. Within- and between-day determinations of measurement precision and accuracy for both compounds validated the suitability of this assay method.
Evaluation of VIDAS® Immuno-Concentration Salmonella Assay Plus Selective Plate Method (Hektoen Enteric, Bismuth Sulfite, Salmonella Identification) for Detection of Salmonella in Selected Foods: Collaborative Study
Authors: Lepper Wendy A , Schultz Ann M , Curiale Michael S , Johnson Ronald L ,   Collaborators:, Agin J , Campbell S , Carver C , Cherney D , Copeland F , Ekholm D , Eklund C , Gangar V , Gardner F , Herbst K , High E , Kallstrom C , Lee J , Lucas J , Lyons W , Maselli M , Miele M , Muehlenkamp E , Muzzy T , Nutsch A , Parra G , Post L , Ryser E , Schultz A , Scorah C , Shebuski J , Shields J , Smith J , Smith M , Stawick B , Trefla J , Vasavada P C , Vought K , Williams J , Witt J , Woodruff T
Published: February 2020

The VIDAS Immuno-concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, bismuth sulfite, Salmonella identification) method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Thirty-two laboratories participated in the evaluation. Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. The 2 methods were in agreement for 1283 of the 1440 test samples. Of the 157 test samples not in agreement, 82 were VIDAS ICS plus selective plate-positive and BAM/AOAC-negative, and 75 were VIDAS ICS plus selective plate-negative and BAM/AOAC-positive.
Salmonella in Selected Foods by VIDAS® Immuno-Concentration Salmonella Plus Selective Plate Method (Hektoen Enteric, Xylose Lysine Desoxycholate, Bismuth Sulfite): Collaborative Study
Authors: Lepper Wendy A , Schultz Ann M , Curiale Michael S , Johnson Ronald L ,   Collaborators:, Agin J , Campbell S , Carver C , Cherney D , Copeland F , Ekholm D , Eklund C , Gangar V , Gardner F , Herbst K , High E , Kallstrom C , Lee J , Lucas J , Lyons W , Maselli M , Miele M , Muehlenkamp E , Muzzy T , Nutsch A , Parra G , Post L , Ryser E , Schultz A , Scorah C , Shebuski J , Shields J , Smith J , Smith M , Stawick B , Trefla J , Vasavada P C , Vought K , Williams J , Witt J , Woodruff T
Published: February 2020

The VIDAS Immuno-concentration Salmonella (ICS) plus selective plate method (Hektoen enteric, xylose lysine desoxycholate, bismuth sulfite) method for the detection of Salmonella was compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Thirty-two laboratories participated in the evaluation. Each laboratory tested one or more of the 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. The 2 methods were in agreement for 1297 of the 1455 samples. Of the 158 samples not in agreement, 82 were VIDAS ICS plus selective plate-positive and BAM/AOAC-negative, and 76 were VIDAS ICS plus selective plate-negative and BAM/AOAC-positive.
Determination of Cadmium, Aluminium, and Copper in Beer and Products Used in Its Manufacture by Electrothermal Atomic Absorption Spectrometry
Authors: Viñas Pilar , Aguinaga Nerea , López-García Ignacio , Hernández-Córdoba Manuel
Published: February 2020

Procedures were developed for determining cadmium, aluminium, and copper in beer and the products used in its manufacture by electrothermal atomic absorption spectrometry. Beer samples were injected into the furnace and solid samples were introduced as suspensions after preparation in a medium containing hydrogen peroxide, nitric acid, and ammonium dihydrogen phosphate for cadmium atomization. Calibration was performed with aqueous standards, and characteristic masses and detection limits were, respectively, 1 and 0.3 pg for cadmium, 18 and 5.4 pg for aluminium, and 5.6 and 6.8 pg for copper. Different samples of beer, wort, brewer's yeast, malt, raw grain, and hops were analyzed by the proposed procedures. Cadmium was found in low concentrations (0.001–0.08 μg/g and 0–1.3 μg/mL); copper (3–13 μg/g and 25–137 μg/mL) and aluminium (0.6–9 μg/g and 0.1–2 μg/mL) were found at higher levels. The reliability of the procedure was confirmed by comparing the results obtained with others based on microwave oven sample digestion, and by analyzing several certified reference materials.
Detection of Genetically Modified Organisms in Foods by Protein- and DNA-Based Techniques: Bridging the Methods
Authors: Duijn Gert van , Biert Ria van , Bleeker-Marcelis Henriette , Boeijen Ineke van , Adan Abdi Jama , Jhakrie Soeniel , Hessing Martin
Published: February 2020

According to European Commission (EC) Regulation 1139/98, foods and food ingredients that are to be delivered to the final consumer in which either protein or DNA resulting from genetic modification is present, shall be subject to additional specific labeling requirements. Since 1994, genetically altered tomatoes, squash, potatoes, canola, cotton, and soy have been on the market. Recently, insect-resistant and herbicide-tolerant maize varieties have been introduced. Soy and maize are 2 of the most important vegetable crops in the world. During the past 4 years, both protein- and DNA-based methods have been developed and applied for detection of transgenic soy and maize, and their derivatives. For protein-based detection, specific monoclonal and polyclonal antibodies have been developed; for immunochemical detection, Western blot analysis and enzyme-linked immunosorbent assays are the most prominent examples. For detection of genetically modified organisms (GMOs) at the level of DNA, polymerase chain reaction-based methods are mainly used. For these reactions, highly specific primer sets are needed. This study compares the principally different methods. Specificity of methods and the possible risks of false-positive or false-negative results are considered in relation to sampling, matrix effects, and food processing procedures. In addition, quantitative aspects of protein- and DNA-based GM detection methods are presented and discussed. This is especially relevant as EC regulation 49/2000, which defines a threshold for an unintentional comingling of 1%, came into force on April 10, 2000.
Development and Validation of a Cost-Effective, Efficient, and Robust Liquid Chromatographic Method for the Simultaneous Determination of the Acetyl and Succinoyl Content in Hydroxypropyl Methylcellulose Acetate Succinate Polymer
Authors: Chen Raymond , Sekulic Sonja , Zelesky Todd
Published: February 2020

A reversed-phase liquid chromatographic method was developed and validated for the determination of the content of free acetic acid, free succinic acid, acetyl substituents, and succinoyl substituents in hydroxypropyl methylcellulose acetate succinate (HPMCAS; Chemical Abstracts Service Registry No. 71138-97-1) polymer. This single new method gave accurate and precise measurement of both acetyl and succinoyl substituents, which had previously required 3 Japanese Pharmaceutical Excipients (JPE) methods to accomplish. Consequently, analysis time and turnaround time are decreased significantly. Furthermore, this method can also separate and determine the free acetic and succinic acids in HPMCAS polymer, a task that the corresponding JPE method cannot achieve. The values for accuracy (average recovery from 12 standard samples) were 99.9% for acetic acid and 99.8% for succinic acid. The values for injection precision (relative standard deviation [RSD]) were 0.11% for acetic acid and 0.28% for succinic acid. The values for intermediate precision (RSD) were 1.25% for determination of the acetyl content at the 8.78% (w/w) level and 1.33% for determination of the succinoyl content at the 10.9% (w/w) level. The values for intermediate precision (RSD) were 5.98% for determination of free acetic acid at the 0.12% (w/w) level and 5.13% for determination of free succinic acid at the 0.029% (w/w) level. The method was proven to be robust with respect to variation in the pH of the mobile phase, the concentration of potassium dihydrogen phosphate, and the flow rate. The method is well suited for quality control in today's fast-paced pharmaceutical laboratories.
Biosensor Immunoassay of Ivermectin in Bovine Milk
Authors: Samsonova Jeanne V , Baxter G Andrew , Crooks Steven R H , Elliott Christopher T
Published: February 2020

A rapid and sensitive biosensor immunoassay was developed for determination of ivermectin residues in bovine milk. A detection limit of 16.2 ng/mL was achieved. A Biacore optical biosensor based on surface plasmon resonance was used, and a range of extraction techniques was investigated. In the final assay procedure, ivermectin was extracted with acetonitrile followed by C8 solid-phase extraction cleanup. It was proven experimentally that 2 methods of milk storage, freezing or addition of mercury-containing compounds as preservatives, could be used without considerable change in detected concentrations (samples were fortified with ivermectin after storage). The average values for milk samples spiked at 100 and 50 ng/mL concentrations were 102.6 and 51.5 ng/mL, respectively. Extraction and analysis of 20 milk samples were performed within a single working day.
Method Validation Study of Hypoglycin A Determination in Ackee Fruit
Authors: Ware George M
Published: February 2020

A study was conducted to validate the performance characteristics of a published method entitled “Reversed-Phase Liquid Chromatographic Detection of Hypoglycin A in Canned Ackee Fruit Sample.” Hypoglycin A (HG-A) was extracted from ackee fruit with 80% ethanol–water, centrifuged, and filtered; the sample extract then was reacted with phenylisothiocyanate. HG-A was separated by reversed-phase chromatography as the phenylthiocarbamyl derivative and detected at the low nanogram level using a UV detector at 254 nm. A study was conducted to determine recovery of HG-A added to a control ackee fruit sample. A control sample containing a low level of HG-A was spiked with 403.2, 201.6, 96.8, and 48.4 μg HG-A/g ackee fruit, respectively. Twelve replicates were analyzed for each spike level. The mean percent recovery ± standard deviation for spike levels 403.2, 201.6, 96.8, and 48.4 μg HG-A/g were 94.37 ± 1.27, 99.12 ± 2.09, 107.95 ± 5.42, and 129.18 ± 15.32%, respectively. The percent coefficient of variation (%CV) for spike levels 403.2, 201.6, 96.8, and 48.4 μg HG-A/g were 1.35, 2.11, 5.02, and 11.86%, respectively. The recovery data indicate that HG-A can be recovered from ackee fruit with excellent accuracy and precision. Precision data obtained from replicate assays of ackee fruit naturally contaminated with low, medium, and high HG-A levels is presented.
Optimized Determination of Calcium in Grape Juice, Wines, and Other Alcoholic Beverages by Atomic Absorption Spectrometry
Authors: Olalla Manuel , González Maria Cruz , Cabrera Carmen , Gimenez Rafael , López Maria Carmen
Published: February 2020

This paper describes a study of the different methods of sample preparation for the determination of calcium in grape juice, wines, and other alcoholic beverages by flame atomic absorption spectrometry; results are also reported for the practical application of these methods to the analysis of commercial samples produced in Spain. The methods tested included dealcoholization, dry mineralization, and wet mineralization with heating by using different acids and/or mixtures of acids. The sensitivity, detection limit, accuracy, precision, and selectiviy of each method were established. Such research is necessary because of the better analytical indexes obtained after acid digestion of the sample, as recommended by the European Union, which advocates the direct method. In addition, although high-temperature mineralization with an HNO3–HClO4 mixture gave the best analytical results, mineralization with nitric acid at 80°C for 15 min gave the most satisfactory results in all cases, including those for wines with high levels of sugar and beverages with high alcoholic content. The results for table wines subjected to the latter treatment had an accuracy of 98.70–99.90%, a relative standard deviation of 2.46%, a detection limit of 19.0 μg/L, and a determination limit of 31.7 μg/L. The method was found to be sufficiently sensitive and selective. It was applied to the determination of Ca in grape juice, different types of wines, and beverages with high alcoholic content, all of which are produced and widely consumed in Spain. The values obtained for Ca were 90.00 ± 20.40 mg/L in the grape juices, 82.30 ± 23.80 mg/L in the white wines, 85.00 ± 30.25 mg/L in the sweet wines, 84.92 ± 23.11 mg/L in the red wines, 85.75 ± 27.65 mg/L in the rosé wines, 9.51 ± 6.65 mg/L in the brandies, 11.53 ± 6.55 mg/L in the gin, 7.3 ± 6.32 mg/L in the pacharán, and 8.41 ± 4.85 mg/L in the anisettes. The method is therefore useful for routine analysis in the quality control of these beverages.
Simultaneous Determination of Nickel, Iron, and Copper in Margarine by Inductively Coupled Plasma–Atomic Emission Spectroscopy after Sample Emulsification
Authors: Benzo Zully , Marcano Eunice , Gómez Clara , Ruiz Frine , Salas Janeth , Quintal Manuelita , Garaboto Angel , Murillo Miguel
Published: February 2020

Nickel, iron, and copper were determined in margarine samples by using emulsification followed by inductively coupled plasma–atomic emission spectroscopy. Sample treatment and instrumental conditions were optimized, and the results were compared with those obtained by a pseudodigestion method in order to evaluate the compatibility of both methodologies. The optimum amount of margarine in the emulsion was 35% when the surfactant Tween 80 was added as the emulsifier. Copper was below the detection limits of both methodologies, i.e., digestion and emulsion; iron and nickel concentrations found by both methodologies were similar. The detection limits of the emulsion method were 0.002, 0.015, and 0.092 mg/kg for copper, iron, and nickel, respectively. A benefit of the emulsion method is that laborious and lengthy sample digestion procedures are avoided. In addition, accurate and precise results are obtained. Recoveries with the emulsion method ranged from 101 to 104%, with relative standard deviations of ≤6%.
Spectrophotometric Determination of Three Anti-Ulcer Drugs Through Charge-Transfer Complexation
Authors: Al-Ghannam Sheikha , Belal Fathalla
Published: February 2020

A simple charge-transfer complexation method is described for the spectrophotometric assay of nizatidine, ranitidine, and famotidine. This method is based on interaction of these drugs, as n-electron donors, with 7,7,8,8-tetracyanoquinodimethane, as the π-acceptor, in acetonitrile to give highly colored green radical anions that are measured at 840 nm. Calibration graphs for the 3 compounds are linear over the concentration ranges of 1–6 μg/mL for nizatidine and ranitidine and 1–7 μg/mL for famotidine, with correlation coefficients (n = 6) of >0.999. The conditioned stability constants and the free energy changes were measured; the values obtained were generally high and negative, respectively, suggesting highly stable complexes. The proposed method was successfully applied to the determination of the drugs in pharmaceutical preparations. The assay results were in accordance with those obtained by using reference methods.
Detection of Enteroviruses in Shellfish by Fluorogenic Polymerase Chain Reaction Integrated with 96-Well Microplate Scanning
Authors: Shiekh Y Carol , Baric Ralph S
Published: February 2020

A one-step procedure was developed to confirm viral targets by using a fluorometric 96-well microplate scanner following polymerase chain reaction (PCR). The fluorogenic PCR, integrated with fluorometric scanning, measured the end point fluorescence of viral PCR amplicon/probe hybrids and permitted the use of nonfluorogenic PCR conditions with addition of a Cy3 fluorophore-labeled linear probe for viruses. This linear probe generated higher ratios of viral signal-to-noise than a comparative beacon probe. Detection efficiency with a Cy3/quencher linear probe was comparable with Southern analysis at the level ≥0.27 plaque-forming units (PFU) of poliovirus/PCR. For the reaction containing <0.27 PFU, the fluorometric measurements of the first-round PCR viral amplicon were not as sensitive as Southern analysis; however, equivalent sensitivities were achieved with fluorogenic nested PCR. Concentrates of 11 oyster samples exposed to municipal sewage were tested for enteroviruses; the fluorogenic detection correlated 100% with Southern analysis. This method using fluorometric scanning of viral amplicon is simple; it requires neither continuously monitoring equipment nor redesigning PCR primers; and it accurately detects enteroviruses in oyster sample concentrates in less time than classic spectrophotometry or Southern analysis.
Determination of Cry9C Protein in Processed Foods Made with StarLink™ Corn
Authors: Diaz Carmen , Fernandez Cecilia , McDonald Regina , Yeung Jupiter M
Published: February 2020

StarLink™ (Aventis CropScience US) hybrid corn has been genetically modified to contain a pesticidal protein, Cry9C, which makes it more resistant than traditional varieties to certain types of corn insect pests. Unlike other varieties of genetically engineered corn, the U.S. Environmental Protection Agency authorized the use of StarLink corn for animal feed and industrial use only, not for human consumption. However, some Cry9C-containing corn was mistakenly or inadvertently comingled with yellow corn intended for human food use. Because corn containing the Cry9C construct was not approved for human use, the U.S. Food and Drug Administration considers food containing it to be adulterated. Consequently, this regulatory violation resulted in hundreds of recalls of corn-based products, such as taco shells, containing cry9C DNA. Detecting the novel protein in StarLink corn is an emerging issue; therefore, there is no standardized or established analytical method for detecting Cry9C protein in processed foods. We developed a procedure for quantitation of Cry9C protein, with validation data, in processed food matrixes with a limit of quantitation at 1.7 ng/g (ppb), using a commercial polyclonal antibody-based Cry9C kit that was intended for corn grain samples. Intra- and interassay coefficients of variation were 2.8 and 11.8%, respectively. Mean recoveries were 73 and 85% at 2 and 5 ng/g Cry9C fortifications, respectively, for 19 control non-StarLink corn-based matrixes. Our data demonstrate only 0–0.5% of Cry9C protein survived the processing of tortilla chips and soft tortillas made from 100% StarLink corn, resulting in levels from below the detection limit to 45 ppb.
Determination of Vegetal Proteins in Milk Powder by Sodium Dodecyl Sulfate–Capillary Gel Electrophoresis: Interlaboratory Study
Authors: Manso María A , Cattaneo Tiziana Maria , Barzaghi Stefania , Olieman Cornelis , López-Fandiño Rosina ,   Collaborators:, Leaver J , Otte J , S�nchez A , Svenning C , Tirelli A , Vegarud G
Published: February 2020

An interlaboratory study, with the participation of 8 laboratories, was conducted to evaluate a sodium dodecyl sulfate–capillary gel electrophoresis method for determination of adulteration of milk powder with soy and pea proteins. Calibration standards (0–8%, w/w, soy and pea protein in total protein) and adulterated skim milk powders (0–5%, w/w, soy and pea proteins in total protein) were produced. Vegetal proteins were determined after removal of milk proteins by pretreatment of the samples with tetraborate–EDTA buffer, pH 8.3. Repeatability standard deviations ranged from 9 to 15% and reproducibility standard deviations ranged from 25 to 30% in the samples containing 5% vegetal protein in total protein.
Comparison of Five Extraction Methods for Determination of Incurred and Added Pesticides in Dietary Composites
Authors: Rosenblum Laura , Garris Sherry T , Morgan Jeffrey N
Published: February 2020

The National Exposure Research Laboratory of the U.S. Environmental Protection Agency conducts research to measure exposure of individuals to chemical pollutants through the diet. In support of this research, methods are being evaluated for the determination of pesticides in dietary composite samples. In the present study, Soxhlet, blender, microwave-assisted, pressurized fluid, and supercritical fluid extraction methods were compared for the determination of incurred and added pesticides in 4 dietary composites, which varied in fat and water content. Incurred pesticides were chlorothalonil, chlorpyrifos, DDE, dicloran, dieldrin, endosulfan I, malathion, cis- and trans-permethrin, and trifluralin. Added pesticides were α- and γ-chlordane, hexachlorobenzene, and fonofos. Concentrations of the individual pesticides were between 0.2 and 20 ng/g composite. All 5 methods tested could extract pesticides from dietary composites. Most incurred pesticides were recovered from the dietary composites within the range of 59–140% of expected values. Recoveries of added pesticides were between 60 and 130%. Microwave-assisted extraction led to significantly higher concentrations of 7 pesticides. Blender extraction yielded significantly higher concentrations of chlorothalonil and fonofos. Water content was a significant factor in the recovery of chlorothalonil, and fat content was a significant factor in the recovery of fonofos. In designing an exposure study, the selection of the extraction method would be determined by number of samples to be extracted, analyte stability, and cost.
Novel Chromatographic Separation and Carbon Solid-Phase Extraction of Acetanilide Herbicide Degradation Products
Authors: Shoemaker Jody A
Published: February 2020

One acetamide and 5 acetanilide herbicides are currently registered for use in the United States. Over the past several years, ethanesulfonic acid (ESA) and oxanilic acid (OA) degradation products of these acetanilide/acetamide herbicides have been found in U.S. ground waters and surface waters. Alachlor ESA and other acetanilide degradation products are listed on the U.S. Environmental Protection Agency's (EPA) 1998 Drinking Water Contaminant Candidate List. Consequently, EPA is interested in obtaining national occurrence data for these contaminants in drinking water. EPA currently does not have a method for determining these acetanilide degradation products in drinking water; therefore, a research method is being developed using liquid chromatography/negative ion electrospray/mass spectrometry with solid-phase extraction (SPE). A novel chromatographic separation of the acetochlor/alachlor ESA and OA structural isomers was developed which uses an ammonium acetate–methanol gradient combined with heating the analytical column to 70°C. Twelve acetanilide degradates were extracted by SPE from 100 mL water samples using carbon cartridges with mean recoveries >90% and relative standard deviations ≤16%.