bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous Quantitation of Aspergillus flavus/A. parasiticus and Aflatoxins in Peanuts
Authors: Dorner Joe W
Published: February 2020

A method was developed for simultaneous quantitation of Aspergillus flavus/A. parasiticus and aflatoxins in peanuts. Peanut samples were ground with an equal weight of water in a vertical cutter mixer to produce a slurry. Separate subsamples were taken for dilution-plating to determine total colony forming units (CFU)/g of A. flavus/A. parasiticus and for liquid chromatographic analysis to determine aflatoxin concentrations. Dry-grinding peanuts for homogenization of aflatoxins produced high temperatures that killed most of the A. flavus/A. parasiticus propagules. Addition of water to produce a slurry kept the temperature from rising above levels that killed the fungi. A 7 min grind time provided optimal homogenization for both the fungi and aflatoxins, so long as the temperature of the slurry did not exceed 45°C. In the analysis of 60 shelled peanut samples, total aflatoxin concentrations ranged from 0 to 10 000 ng/g and total A. flavus/A. parasiticus ranged from 1.4 × 103 to 3.2 × 106 CFU/g. Regression analysis showed a significant positive correlation (p < 0.0001) between the quantities of A. flavus/A. parasiticus and aflatoxin (R2 = 0.82).
Statistical Approach for Risk Assessment of Aflatoxin Sampling Plan Used by Manufacturers for Raw Shelled Peanuts
Authors: Vandeven Mark , Whitaker Thomas , Slate Andy
Published: February 2020

Processed food manufacturers often use acceptance sampling plans to screen out lots with unacceptable levels of contamination from incoming raw material streams. Sampling plan designs are determined by specifying sample sizes, sample preparation methods, analytical test methods, and accept/reject criteria. Sampling plan performance can be indicated by plotting acceptance probability versus contamination level as an operating characteristic (OC) curve. In practice, actual plan performance depends on the level of contamination in the incoming lot stream. This level can vary considerably over time, among different crop varieties, and among locales. To better gauge plan performance, a method of coupling an OC curve and crop distributions is proposed. The method provides a precise probabilistic statement about risk and can be easily performed with commercial spreadsheet software.
Rapid Methods for Detection and Enumeration of Campylobacter spp. in Foods
Authors: Wang Haiyan
Published: February 2020

Campylobacter spp. are the most commonly reported bacterial cause of acute diarrheal disease in humans throughout the world. Traditional cultural methods for the detection and quantitation of Campylobacter spp. are slow and tedious; therefore, specific, sensitive, and rapid methods for campylobacters are needed to collect sufficient data for risk assessment and food safety policy development. We developed several rapid methods based on polymerase chain reaction (PCR), DNA hybridization, hydrophobic grid membrane filters (HGMFs), and enzyme immunoassays (EIAs). A PCR assay targeting C. jejuni, combined with a simple sample preparation procedure, detects as few as 0.3 most probable number (MPN)/mL C. jejuni in naturally contaminated chicken rinses after 20–24 h enrichment. An HGMF–EIA method using a commercial polyclonal antibody for Campylobacter detects and enumerates thermophilic Campylobacter spp. from spiked chicken rinse and milk, and naturally contaminated chicken rinses. A C. jejuni–specific probe in an HGMF–DNA hybridization protocol specifically detects and quantitates C. jejuni in food samples. A dot-blot EIA combined with an MPN procedure quantitates thermophilic campylobacters from samples that might be difficult to filter through HGMFs.
Assurance® Enzyme Immunoassay Eight Hour Method for Detection of Enterohemorrhagic Escherichia coli O157:H7 in Raw and Cooked Beef (Modification of AOAC Official Method 996.10): Collaborative Study
Authors: Feldsine Philip T , Kerr David E , Leung Stephanie C , Lienau Andrew H , Miller Stephanie M , Mui Linda A ,   Collaborators:, Anderson G , Beasley M , Dillon J , Dombroski P , Forgey R , Hernandez C , Hopkins S , Johnson K , Meier J , Nguyen T , Ortega R , Reynolds J , Smith J , Solis D , Summers C , Terry J , Tuncan E , Vrana D , Warren W , Wood S
Published: February 2020

AOAC Official Method 996.10, Assurance® Enzyme Immunoassay (EIA) for Escherichia coli O157:H7 (EHEC), was modified to incorporate a new enrichment protocol using BioControl EHEC8™ medium for testing raw and cooked beef. Foods were tested by EIA and the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) enrichment conditions and the FDA Bacteriological Analytical Manual (BAM) isolation and confirmation techniques. A total of 14 collaborators participated. Raw and cooked ground beef were inoculated with E. coli O157:H7 at 2 different levels: a high level where predominantly positive results were expected, and a low level where fractional recovery was anticipated. Collaborators tested 378 test portions and controls by both the 8 h EIA and the USDA/FSIS enrichment methods, for a total of 756 test portions. Of the 378 paired test portions, 75 were positive and 212 were negative by both methods. Thirteen test portions were presumptively positive by EIA and could not be confirmed culturally; 30 were negative by EIA, but confirmed positive by culture; and 65 were negative by the culture method, but confirmed positive by the EIA method. There was no statistical difference between results obtained with the Assurance EIA for EHEC 8 h method and the culture method for raw ground beef. The Assurance EIA had a significantly higher recovery for cooked beef.
Spectrofluorimetric Determination of Formaldehyde in Maple Syrup
Authors: Lagace Luc , Dumont Johanne , Brazeau Germain , Soucy Andree , Haché Jonathan , Marquis Vincent
Published: February 2020

A quick and simple method was developed for determination of formaldehyde in maple syrup. In this method, formaldehyde reacts with Fluoral P to form a complex which is chemically extracted by isobutanol and determined by spectrofluorimetry. Performance, as gauged by the limits of detection (0.16 mg/kg) and quantitation (0.21 mg/kg), recovery (>79%), and variability (1.9–16.1%, depending on fortification level and class of syrup) were superior to the current official AOAC standard method.
Differential Pulse Voltammetric Assay of Lercanidipine in Tablets
Authors: Álvarez-Lueje Alejandro , Pujol Sara , Núñez-Vergara Luis J , Squella Juan A
Published: February 2020

Lercanidipine in ethanol–0.04M Britton-Robinson buffer (20 + 80) gives an irreversible anodic response on a glassy carbon electrode in a broad pH range (2–12) that depends on pH. This signal can be attributed to oxidation of the 1,4-dihydropyridine ring to give the corresponding pyridine derivative. For analytical purposes, differential pulse voltammetry at pH 4 was selected. Under these conditions, good values of both within- and interday reproducibility were obtained, with coefficient of variation (CV) values of 1.56 and 1.70%, respectively, for 10 successive runs. For quantitation, the calibration curve method was used for lercanidipine concentrations ranging from 1 × 10−5 to 1 × 10−4M. The detection and quantitation limits were 1.39 × 10−5 and 1.49 × 10−5, respectively. A liquid chromatographic method with electrochemical detection was used for comparison. The voltammetric method showed good selectivity with respect to both excipients and degradation products. The recovery study exhibited a CV of 0.94% and an average recovery of 98.3%, and it was not necessary to treat the sample before the analysis. The method was successfully applied to the individual tablet assay of lercanidipine in commercial tablets.
Use of Hydrophilic Hydroxypropyl Methacrylate/Ethylene Glycol Methacrylate Packing Material in Size-Exclusion Chromatography
Authors: Vianna-Soares Cristina D , Kim Cherng-Ju , Borenstein Michael R
Published: February 2020

Spherical particles of hydroxypropyl methacrylate/ethylene glycol methacrylate copolymer were synthesized in-house for use in size-exclusion chromatography. The porous hydrophilic material was packed in glass and stainless steel columns to evaluate their chromatographic performance. The support particles were small (approximately 20 Å), and the average pore size was in the low range of mesopores (approximately 100 Å). The packed columns were calibrated by using polysaccharide dextrans, showing a good range of separation for molecular weights between 10 000 and 600 000 daltons. The packing material appears to separate the large molecules through the size-exclusion mechanism. Polysaccharides and polypeptides dissolved in adequate mobile phases were injected into the packed column. The separation of the macromolecules was consistent with the size-exclusion mechanism. Application of the packing material to the separation of small molecules (alkyl alcohols) was also investigated.
Determination of Deoxynivalenol in Whole Wheat Flour and Whear Bran
Authors: Rupp Heidi S
Published: February 2020

A liquid chromatographic (LC) method was developed for determining deoxynivalenol (DON) in whole wheat flour and wheat bran. A 15 g test sample was extracted with acetonitrile–water (84 + 16, v/v) and applied to a Romer MycoSep cleanup column. The eluate was dried and then reconstituted in a 0.1M phosphate buffer, pH 7.0, and applied to a Vicam DONtest-LC cleanup column. The methanol eluate was chromatographed with a methanol–water (17 + 83, v/v) mobile phase on a C18 column with UV detection at 220 nm. Five replicates at each of 5 fortification levels (0.25, 0.50, 1.0, 2.0, and 4.0 ppm), plus 5 controls, were determined for both whole wheat flour and wheat bran. For flour, the average recoveries were 72.2–91.5% with relative standard deviations (RSDs) of 4.9–18.4%. The intra-assay flour recovery was 82.4% with 9.8% RSD. A 5 replicate sample of naturally incurred wheat had an average of 1.1 ppm DON with 6.7% RSD. For bran, average recoveries of fortified samples were 69.5–99.7% with RSDs of 1.7–18.8%. The intra-assay bran recovery was 81.5% with 8.9% RSD. The limit of detection (about 3× noise) for the method is 0.05 ppm; the correlation coefficient (linearity) was >0.9995. The DON peak was clearly identified and easily integrated in the chromatograms.
Stability of Florfenicol in Drinking Water
Authors: Hayes John M , Eichman Jonathan , Katz Terry , Gilewicz Rosalia
Published: February 2020

Florfenicol, a broad-spectrum antibiotic, is being developed for veterinary application as an oral concentrate intended for dilution with drinking water. When a drug product is dosed via drinking water in a farm setting, a number of variables, including pH, chlorine content, hardness of the water used for dilution, and container material, may affect its stability, leading to a decrease in drug potency. The stability of florfenicol after dilution of Florfenicol Drinking Water Concentrate Oral Solution, 23 mg/mL, with drinking water was studied. A stability-indicating, validated liquid chromatographic method was used to evaluate florfenicol stability at 25°C at 5, 10, and 24 h after dilution. The results indicate that florfenicol is stable under a range of simulated field conditions, including various pipe materials and conditions of hard or soft and chlorinated or nonchlorinated water at low or high pH. Significant degradation (>10%) was observed only for isolated combinations in galvanized pipes. Analysis indicated that the florfenicol concentration in 8 of the 12 water samples stored in galvanized pipes remained above 90% of the initial concentration (100 mg/L) for 24 h after dilution.
Spectrofluorimetric and Spectrophotometric Determination of Gliclazide in Pharmaceuticals by Derivatization with 4-Chloro-7-nitrobenzo-2-oxa-1,3-diazole
Authors: El-Enany Nahed
Published: February 2020

Accurate, sensitive, and simple spectrophotometric and spectrofluorimetric methods were developed for the determination of gliclazide in pharmaceutical formulations and biological fluids. Both methods are based on a coupling reaction between gliclazide and 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in borate buffer, pH 7.8, in which a yellow reaction product that can be measured spectrophotometrically at 400 nm was developed. The same product exhibited a yellow fluorescence at 470 nm upon excitation at 400 nm. The absorbance–concentration plot was rectilinear over the range of 2–20 μg/mL with minimum detectability [signal-to-noise (S/N) ratio = 2] of 0.2 μg/mL (6.18 × 10−7 M); the fluorescence–concentration plot was rectilinear over the range of 0.2–2.5 μg/mL with minimum detectability (S/N = 2) of 0.02 μg/mL (6.18 × 10−8M). The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. Both methods were successfully applied to the analysis of commercial tablets. The results were in good agreement with those obtained with the official and reference spectrophotometric methods. A proposal of the reaction pathway was presented.
Determination of Retinyl Palmitate (Vitamin A) in Fortified Fluid Milk by Liquid Chromatography: Collaborative Study
Authors: Hite Douglas A ,   Collaborators:, Angelo L , Bhandari S , Bhattacharyya S , Bonnin E , Brousseau R , Ellis C , Faulkner H , Foran M , Goins D , Hill K , Jesse C , Kreuger D , McGuire J , Mioc B , O’Neal D , Patel P , Porter E , Wagner C
Published: February 2020

A liquid chromatographic (LC) method was developed for fast and simple measurement of retinyl palmitate (vitamin A) in fortified milk. Retinyl acetate internal standard was added to a test portion of milk followed by extraction into hexane. The hexane extract was analyzed by LC using a normal-phase silica gel column equilibrated with mobile phase (conditioned hexane–isopropanol, 99.85 + 0.15, v/v) about 1 h before injections. The retinyl palmitate concentration was calculated by using a relative response factor determined with calibration standards. In the collaborative study, 11 laboratories analyzed 13 pairs of fluid milk materials in blind duplicate. Twelve of the materials were composed of skim milk (<0.5% fat), 1% fat milk, 2% fat milk, and 1% fat chocolate milk. Each material was fortified at 3 concentrations of retinyl palmitate of approximately 581 μg/L (1000 IU/qt), 1163 μg/L (2000 IU/qt), and 2236 μg/L (4000 IU/qt). The 13th material, unfortified skim milk, served as a matrix blank. Repeatability standard deviations (RSDr) without outliers ranged from 1.5 to 5.7% and reproducibility standard deviations (RSDR) without outliers ranged from 5.0 to 22.7%. cis-Isomers co-eluted with the predominant trans-retinyl palmitate isomer and were included in the results reported by all the collaborative laboratories. Endogenous long-chain esters from milk fat were also measured with the retinyl palmitate additive. The Study Director recommends that this method for determination of retinyl palmitate in fluid milk by LC be adopted First Action.
Method Validation for Determination of Alkaloid Content in Goldenseal Root Powder
Authors: Weber Holly A , Zart Matthew K , Hodges Andrew E , White Kellie D , Barnes Sarah M , Moody Leslie A , Clark Alice P , Harris Roger K , Overstreet J Diane , Smith Cynthia S
Published: February 2020

A fast, practical ambient extraction methodology followed by isocratic liquid chromatography (LC) analysis with UV detection was validated for the determination of berberine, hydrastine, and canadine in goldenseal (Hydrastis canadensis L.) root powder. The method was also validated for palmatine, a major alkaloid present in the possible bioadulterants Coptis, Oregon grape root, and bar-berry bark. Alkaloid standard solutions were linear over the evaluated concentration ranges. The analytical method was linear for alkaloid extraction using 0.3–2 g goldenseal root powder/100 mL extraction solvent. Precision of the method was demonstrated using 10 replicate extractions of 0.5 g goldenseal root powder, with percent relative standard deviation for all 4 alkaloids ≤1.6. Alkaloid recovery was determined by spiking each alkaloid into triplicate aliquots of neat goldenseal root powder. Recoveries ranged from 92.3% for palmatine to 101.9% for hydrastine. Ruggedness of the method was evaluated by performing multiple analyses of goldenseal root powder from 3 suppliers over a 2-year period. The method was also used to analyze Coptis root, Oregon grape root, barberry bark, and celandine herb, which are possible goldenseal bioadulterants. The resulting chromato-graphic profiles of the bioadulterants were significantly different from that of goldenseal. The method was directly transferred to LC with mass spectrometry, which was used to confirm the presence of goldenseal alkaloids tetrahydro-berberastine, berberastine, canadaline, berberine, hydrastine, and canadine, as well as alkaloids from the bioadulterants, including palmatine, jatrorrhizine, and coptisine.
Interactions of Antimicrobials in Milk and Their Detection by the Disk Diffusion Method and Delvotest SP
Authors: Kukurová Iveta , Hozová Bernadetta
Published: February 2020

The combination of more than 2 different microbials might show interactions with various effects (synergistic, additive, antagonistic, or indifferent) on target microorgnisms. An objective of this paper was to evaluate the possible interactions of several antimicrobials—those used most frequently in the treatment of mastitis in clinical veterinary practice (β-lactam antibiotics, aminoglycosides, peptides, other antibiotics, and sulfonamides)—and their consequences on detection limits. In the model experiment with milk artificially altered by means of Delvotest SP and the disk diffusion method with Ba-cillus stearothermophilus var. calidolactis C 953, we observed the synergistic effect between all the antimicrobials tested. The results show that Delvotest SP is more sensitive (approximately 7.5- to 40-fold) than the disk diffusion method in estimating the detection limits of cephalosporin antibiotics.
Interference-Free Determination of Trace Levels of Gold and Palladium in Geological and Metallurgical Samples by Flame Atomic Absorption Spectrometry Coupled with a Flow Injection On-Line Microcolumn Preconcentration and Separation System
Authors: Liu Peng , Pu Qiaosheng , Sun Qiaoyu , Su Zhixing
Published: February 2020

A simple and highly selective method was developed for the routine determination of trace or ultratrace amounts of gold and palladium in geological and metallurgical samples. The method uses flow injection on-line preconcentration and separation with determination by flame atomic absorption spectrometry. Au and Pd in the sample are adsorbed on a 2-mercaptopyrimidine chemically modified silica gel (MPMSG) packed microcolumn in a 0.50M HCl medium and then eluted with 0.5 or 1.0% thiourea solution. The eluates are introduced into the flame atomic absorption spectrometer directly. With the use of a 0.85 mL microcolumn (about 0.14 g MPMSG packed), the present system tolerated concentrations of common base metal ions up to 25.0 mg/mL and concentrations of anions up to 100.0 mg/mL when Au(III) at 0.100 μg/mL and Pd(II) at 0.200 μg/mL were preconcentrated for 60 s with a sample flow rate of 5.0 mL/min. The limits of detection were 3.1 ng/mL for Au(III) and 6.1 ng/mL for Pd(II) with relative standard deviations of ≤2.5%. The analytical results obtained by the proposed method for geological and metallurgical samples were in good agreement with the certified values.
Selective Extraction and Determination of Multiclass Pesticide Residues in Post-Harvest French Beans by Low-Pressure Gas Chromatography/Tandem Mass Spectrometry
Authors: Martínez Vidal Jose L , González-Rodríguez Manuel J , Arrebola Francisco J , Garrido Frenich Antonia , Sánchez López Francisco J , Díez Nielene Mora
Published: February 2020

A selective and reliable extraction procedure was developed and validated to determine multiclass pesticide residues in lyophilized agricultural plants by low-pressure gas chromatography coupled with tandem mass spectrometry. The method is based on a rapid and simple extraction of the lyophilized sample with dichloromethane. The results were compared with those obtained by using fresh and naturally dried samples. Slightly better recoveries and precision values were obtained for the lyophilized samples. The application of the proposed methodology was tested by analyzing French bean plants from an agricultural area of Almería (Spain). The availability of this methodology, which is capable of detecting a high number of analytes in a single analysis, has priority in analyses for a large number of pesticides used on individual commodities.
Single-Laboratory Validation of a Modified Liquid Chromatographic Method with UV Detection for Determination of Trenbolone Residues in Bovine Liver and Muscle
Authors: MacNeil James D , Reid Joann , Neiser Constance D , Fesser Adrian C E
Published: February 2020

Trenbolone acetate is a synthetic testosterone analog registered for use in a number of countries as a growth-promoting hormone, applied as an implant in the ears of feedlot cattle. The method is intended for the detection and quantitation of trace amounts of α- and β-trenbolone in bovine tissues (muscle, liver) by liquid chromatography (LC) with UV detection and eliminates the use of the structural analog, 19-nortestosterone, as an internal standard. Trenbolone residues are extracted from tissues that have been homogenized in sodium acetate with a 3-phase liquid–liquid extraction by adding a mixture of water–acetonitrile–dichloromethane– hexane, with trenbolone residues preferentially partitioned into the middle acetonitrile layer. The extract is passed through solid-phase extraction cartridges (both C18 and silica gel) using, respectively, methanol–water and acetone–toluene as eluents. Reversed-phase high-performance LC separation is performed, an octadecyl-bonded column with methanol–acetonitrile–water used as mobile phase for sample analysis. The limit of detection is 0.2 ng/g in muscle tissue and 0.6 ng/g in liver tissue, with coefficients of variation of 3.5–12.1% for α- and β-trenbolone at concentrations from 0.2 to 4.0 ng/g fortified in muscle and 3.3–26.0% from liver fortified at 0.6–10.0 ng/g. Absolute recoveries of 40–130% were observed, but the use of fortified matrix curves eliminated recovery correction. Critical control points were identified in a pH adjustment step and an evaporation step during method validation, which included ruggedness testing. Analysis of incurred tissues (bovine liver and muscle) stored at –20°C for over 25 weeks did not identify any significant loss of residues.
3M™ Petrifilm™ Staph Express Count Plate Method for the Enumeration of Staphylococcus aureus in Selected Types of Meat, Seafood, and Poultry: Collaborative Study
Authors: McMahon Wendy A , Aleo Victoria A , Schultz Ann M , Horter Barbara L , Lindberg Kathryn G ,   Collaborators:, Allen M , Anderson L , Barnes R , Bellow S , Bokina C , Boulter T , Caulkins L , Ceizyk M , Chavey C , Eastep Y , Gohil V , Guha S , Hall G , Hopkins K , Horter B , Kaufer A , Kaur D , Kim S , Kupski B , Lee J , Lester; T , Musch S , Silbernagel K , Sorce L , Steiner G , Sumpter R , Sutton J , Veach J
Published: February 2020

The 3M™ Petrifilm™ Staph Express Count plate method was compared with AOAC Official Method 975.55 for the enumeration of Staphylococcus aureus in selected foods. Four foods—cooked, diced chicken; cured ham; smoked salmon; and pepperoni—were analyzed for S. aureus by 12 collaborating laboratories. For each food tested, the collaborators received 8 blind test samples consisting of a control sample, a low inoculation level, a medium inoculation level, and a medium inoculation level with background flora, each in duplicate. The mean log10 counts for the methods were comparable for all 4 foods. The repeatability and reproducibility variances of the 24 h Petrifilm Staph Express Count plate method were similar to those of the 72 h standard method.
Immunoaffinity Column Cleanup with Liquid Chromatography Using Post-Column Bromination for Determination of Aflatoxin B1 in Cattle Feed: Collaborative Study
Authors: Stroka Joerg , von Holst Christoph , Anklam Elke , Reutter Matthias ,   Collaborators:, Barmark A , Brera C , Burdaspal P , Daily S , Declercq B , de Jong J , Eckstein H , Eklund E , Felgueiras I , Goto T , Hagler W , Joerissen U , Lew H , Ligi-Martins M , MacDonald S , Macho L , Marzna I , McGrath E , Michelet J Y , Nordkvist E , Noutio K , Pascale M , Roos A , Schwadorf K , Spanjer M , Szymanski L , Visconti A , Walsh M , Werner G , Whitaker T , Wilson D , 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 cattle feed at a possible future European regulatory limit (1 ng/g). The test portion was extracted with acetone–water (85 + 15), 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. Aflatoxin B1 was separated and determined by reversed-phase liquid chromatography (RP–LC) and detected by fluorescence after post column derivatization (PCD) involving bromination. PCD was achieved with either pyridinium hydrobromide perbromide (PBPB), used by 14 laboratories, or an electrochemical cell and addition of bromide to the mobile phase, used by 7 laboratories. Both derivatization techniques were not significantly different when compared by the t-test; the method was statistically evaluated for all laboratories together (bromination and PBPB). The cattle feed samples, both spiked and naturally contaminatedwithaflatoxinB1, were sent to 21 laboratories in 14 different countries (United States, Japan, and Europe). Test portions were spiked at levels of 1.2 and 3.6 ng/g for aflatoxin B1. Recoveries ranged from 74 to 157%. Based on results for spiked samples (blind pairs at 2 levels) as well as naturally con-taminated samples (blind pairs at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 5.9 to 8.7%. The relative standard deviation for reproducibility (RSDR) ranged from 17.5 to 19.6%. The method showed acceptable within-and between-laboratory precision for this matrix, as evidenced by HORRAT values, at the target levels of determination for aflatoxin B1. No major differences in RSD were observed, showing that the composition of the feeds was not a factor for the samples tested and that the method was applicable for all materials used.
Determination of Fluoride in Wine by Fluoride Selective Ion Electrode, Standard Addition Method: Collaborative Study
Authors: Trombella Bruno E , Caputi Arthur , Musso Daniel , Ribeiro Anthony , Ryan Timothy ,   Collaborators:, Andrade G , Burns G , Eder R , Gallego R G , Garcia J , Goriel A , Kupina S , Mabud A , Masschelin; J , Roberts D , Tusseau D , Wittkowski R
Published: February 2020

The accuracy, precision, and reproducibility of a rapid method for determination of fluoride in wine, using a fluoride selective ion electrode, were established by a collaborative study involving 12 laboratories, 5 in Europe and 7 in the United States. The laboratories assayed 6 Youden pairs of fluo-ride-fortified, red and white wine samples with fluoride concentrations ranging from 0.2 to 3.0 mg/L. The relative standard deviations of repeatability ranged from 1.94 to 4.88%; relative standard deviations of reproducibility ranged from 4.15 to 18.40%. HORRAT values ranged from 0.30 to 0.97. The average recovery was 99.97%. Based on the statistical results of this collaborative study, the Study Director recommends that this method be adopted First Action.
Extraction and Determination of Phenolic Derivatives in Water Samples by Using Polyoxyethylene Surfactants and Liquid Chromatography with Photodiode Array Detection
Authors: Santana C Mahugo , Ferrera Z Sosa , Rodríguez J J Santana
Published: February 2020

Methodology based on the cloud-point phenomenon was applied to the comparative study of 3 different polyoxyethylene nonionic surfactants in order to extract and preconcentrate a group of phenolic derivatives in water samples; these phenolic compounds, which were determined by liquid chromatography with UV detection, included 11 pollutants given priority by the U.S. Environmental Protection Agency. The optimum conditions for the extraction and preconcentration of phenolic compounds were established for each surfactant. The surfactant that gave the best extraction and preconcentration of the analytes under study was polyoxyethylene 6 lauryl ether (C12E6) with detection limits of <3.5 μg/L for all the phenolic compounds tested. The method was applied to seawater and depurated wastewater samples.
Speciation and Bioavailability of Selenium in Yeast-Based Intervention Agents Used in Cancer Chemoprevention Studies
Authors: Larsen Erik H , Hansen Marianne , Paulin Helge , Moesgaard Sven , Reid Mary , Rayman Margaret
Published: February 2020

This study investigated the speciation and bioavailability of selenium in yeast-based intervention agents from multiple manufacturers from several time points. Sources of selenized yeast included Nutrition 21 (San Diego, CA), which supplied the Nutritional Prevention of Cancer (NPC) Trial from 1981–1996; Cypress Systems (Fresno, CA; 1997–1999); and Pharma Nord (Vejle, Denmark; 1999–2000), which supplied the Prevention of Cancer by Intervention by Selenium (PRECISE) Trial pilot studies. The low-molecular-selenium species were liberated from the samples by proteolytic hydrolysis followed by separation by ion exchange liquid chromatography and detection by inductively coupled plasma-mass spectrometry. The results for the NPC tablets showed that selenomethionine, together with 3 unidentified selenium compounds, were predominant in the sample hydrolysates. The relative amounts of the 4 selenium species varied (p < 0.05) among several of the 7 tablet batches used during the course of the NPC Trial. In comparison, 5 batches of more recently produced selenized yeasts, which were used as a source of selenium in the PRECISE and other trials, contained less of the unknown compounds and more selenomethionine at 54–60% of the total selenium in the yeasts. One batch of yeast, however (from 1985), which originated from the same producer as the yeast used in the NPC tablets, contained only 27% of selenium in the sample as selenomethionine. Human subjects receiving 200 μg selenium/day in the UK PRECISE Pilot Trial showed a higher concentration (p < 0.01) and higher increase from baseline in plasma selenium than did the same dosage used in the NPC Trial. Differences in intake, speciation, or bioavailability of selenium from the yeast-based supplements in the population groups studied may explain this. Furthermore, the selenium concentration in whole blood from the Danish PRECISE Pilot Trial was higher (p < 0.001) than that obtained with synthetic L-selenomethionine in a comparable group of Danes, both groups having been treated with 300 μg selenium/day.
Qualitative Method for Determination of Aflatoxin B1 in Nuts
Authors: Trullols Esther , Ruisánchez Itziar , Rius F Xavier , Ódena Marta , Feliu M Teresa
Published: February 2020

The proper characterization of a commercial qualitative method for determining aflatoxin B1 in some nuts is described. A qualitative method that provides binary responses of the yes/no type means that the performance parameters have been properly adapted and defined. Performance characteristics such as the cut-off limit, the detection limit, sensitivity, specificity, false-positive and negative rates, and the unreliability or uncertainty region are defined and then estimated by means of the performance characteristic curves. The commercial test kit showed the cut-off limit at 1.6 ng/g, with a sensitivity rate of 95% and a false-negative rate of zero. A modification can be performed to shift the cut-off to 2.0 ng/g, keeping the same values for the sensitivity and false-negative rate.
Methods for Analysis of Conjugated Linoleic Acids and trans-18:1 Isomers in Dairy Fats by Using a Combination of Gas Chromatography, Silver-Ion Thin-Layer Chromatography/Gas Chromatography, and Silver-Ion Liquid Chromatography
Authors: Cruz-Hernandez Cristina , Deng Zeyuan , Zhou Jianqiang , Hill Arthur R , Yurawecz Martin P , Delmonte Pierluigi , Mossoba Magdi M , Dugan Michael E R , Kramer John K G
Published: February 2020

Conjugated linoleic acids (CLA) are octadecadienoic acids (18:2) that have a conjugated double-bond system. Interest in these compounds has expanded since CLA were found to be associated with a number of physiological and pathological responses such as cancer, metastases, atherosclerosis, diabetes, immunity, and body fat/protein composition. The main sources of these conjugated fatty acids are dairy fats. Rumen bacteria convert polyunsaturated fatty acids, especially linoleic and linolenic acids, to CLA and numerous trans- containing mono- and diunsaturated fatty acids. It has been established that an additional route of CLA synthesis in ruminants and monogastric animals, including humans, occurs via Δ9 desaturation of the trans-18:1 isomers. To date, a total of 6 positional CLA isomers have been found in dairy fats, each occurring in 4 geometric forms (cis,trans; trans,cis; cis,cis; and trans,trans) for a total of 24. All of these CLA isomers can be resolved only by a combination of gas chromatography (GC), using 100 m highly polar capillary columns, and silver-ion liquid chromatography, using 3 of these 25 cm columns in series. Complete analysis of all the trans-18:1 isomers requires prior isolation of trans monoenes by silver-ion thin-layer chromatography (TLC), followed by GC analysis using the same 100 m capillary columns operated at low temperatures starting from 120°C. These analytical techniques are required to assess the purity of commercial CLA preparations, because their purity will affect the interpretation of any physiological and/or biochemical response obtained. Prior assessment of CLA preparations by TLC is also recommended to determine the presence of any other impurities. The availability of pure CLA isomers will permit the evaluation and analysis of individual CLA isomers for their nutritional and biological activity in model systems, animals, and humans. These techniques are also essential to evaluate dairy fats for their content of specific CLA isomers and to help design experimental diets to increase the level of the desired CLA isomers in dairy fats. These improved techniques are further required to evaluate the CLA profile in monogastric animals fed commercial CLA preparations for CLA enrichment of animal products. This is particularly important because absorption and metabolism will alter the ingested-CLA profile in the animal fed.
Instrumental Factors Influencing Absorption Measurements for Fluid Food Color Determination
Authors: Montes Cristina , Campos Joaquín , Pons Alicia , Heredia Francisco J
Published: February 2020

The differences in color coordinates obtained from the use of different spectral features in the calculation are studied. Seven groups of food (olive oil, vanilla milkshake, brandy, honey, grape juice, vinegar, and orange juice) and an anthocyanin petunidin solution (natural pigment present in several vegetables) with different pH values were selected. Tristimulus values were calculated by considering the different sources of errors (truncation, abridgement, or different bandwidths). Results obtained were corrected by using the methods recommended (see References). These methods of abridgment work well in general, although in some circumstances (20 nm bandwidth or larger), specific spectral weighting functions have to be used to obtain a negligible error. Therefore, it is interesting to know how much difference can be expected from those factors in order to avoid confusion between color differences attributable to instruments and those attributable to actual color changes.
Applications and Uses of Resistant Starch
Authors: Brown Ian L
Published: February 2020

For the past 30 years there has been a steady increase in our knowledge of the sources, uses and physiological effects of resistant starch. However, it has only been in the past decade that the use of ingredients with a high resistant starch content has occurred in foods, initially in Australia but now throughout the world. Foods containing these resistant starch-rich ingredients include not only staple foods, such as bread and breakfast cereals, but also foods designed for those with special physiological or medical needs, such as celiac sensitivity and ulcerative colitis, or for individuals who are seeking to manage energy intake and control weight. Resistant starch has other benefits when compared with traditional sources of dietary fiber in that the preparation and design of foods with additional health benefits have the appearance, taste, and texture characteristics that encourage people to consume these “better for you” foods. As our knowledge of the range of physiological effects that occur through the consumption of resistant starch increases, more applications will be found for their inclusion in an expanding range of foods around the world.
Determination of Residues of Quaternary Ammonium Disinfectants in Food Products by Liquid Chromatography-Tandem Mass Spectrometry
Authors: van Bruijnsvoort Michel , Rooselaar Joop , Stern Alfred G , Jonker Klaas M
Published: February 2020

A liquid chromatography-tandem mass spectrometry method has been developed for the determination of residues of alkylbenzyldimethyl-ammonium, didecyldimethylammonium, didodecyldimethylammonium, and benzyldodecyl-hydroxyethylammonium compounds in various food matrixes. These quaternary ammonium compounds (QAs) are used in the food industry as disinfectants. According to the Dutch Food Law, the total mass (expressed as cetyltrimethyl-ammonium chloride) of QAs in food products shall not exceed the legislative limit of 0.5 mg/kg. Samples were extracted by a simple salting-out procedure, using acetonitrile and sodium chloride; about 100 samples could be prepared and analyzed daily. Special care had to be taken to thoroughly homogenize samples and to avoid the use of contaminated labware. The method was validated by a procedure in compliance with EU Directive 2002/657. From the matrixes of ice cream and minced meat, recoveries of more than 95% with a relative standard deviation of about 3% were obtained by 3 different analysts (n = 54). Detection limits were in the low μg/kg range. The decision limit (CCα) was determined to be 0.55 mg/kg. Dairy and meat products, collected in The Netherlands, were analyzed (761 samples). In 1% of the meat samples, 2% of the ice cream and milkshake samples, and 24% of the whipped cream samples, the Dutch legislative limit was exceeded. Over 2000 injections could be performed on a single column without deterioration of the peak shapes or recoveries.
Preparation and Certification of Zearalenone Mass Concentration of Two Low-Level Maize Reference Materials
Authors: Krska Rudolf , Josephs Ralf D , Pettersson Hans , MacDonald Susan
Published: February 2020

The contamination of maize by fungi, especially by Fusarium species, is a worldwide problem. One of the most prevalent Fusarium mycotoxins frequently found on European maize is zearalenone (ZON), which has been implicated in a range of human and animal diseases. It shows remarkable estrogenic properties and can cause severe infertility problems in farm animals. Currently, 9 countries have set maximum tolerable levels for ZON in food, ranging from 0 to 1000 μg/kg. This paper describes the preparation of 2 maize reference materials (BCR-716 very low level ZON and BCR-717 low level ZON) and the certification of their individual ZON contents (mass concentration and mass fraction). Uncertainties were calculated in compliance with the Guide to the Expression of Uncertainty in Measurement and include uncertainties that are due to possible inhomogeneity and instability. Finally, BCR-716 was certified at a level of <5 μg/kg and BCR-717 at a level of 83 μ/kg with an expanded uncertainty (k = 2) of 9 μg/kg.
Development of a Solid-Phase Extraction Method for Determination of Pheophorbide a and Pyropheophorbide a in Health Foods by Liquid Chromatography
Authors: Oshima Harumi , Ueno Eiji , Saito Isao , Matsumoto Hiroshi
Published: February 2020

A simple solid-phase extraction (SPE) method was developed for the liquid chromatography (LC) determination of pheophorbide (Phor) a and pyropheophorbide (Pyro) a in health foods such as chlorella, spirulina, etc. The food sample was extracted with 85% (v/v) acetone. The extract was acidified with hydrochloric acid and loaded on a C18 cartridge. After washing with water, Phor a and Pyro a were eluted with the LC mobile phase. Phor a and Pyro a were separated by isocratic reversed-phase LC and quantitated by fluorescence detection. The recoveries for spiked samples of chlorella and the extract were 87.1–102.0%. Commercial health foods (chlorella, spirulina, aloe, kale, Jews mallow, and green tea leaves) were analyzed using the SPE method. The values found for Phor a and Pyro a ranged from 2 to 788 μg/g and from <1 to 24 μg/g, respectively. There was no significant difference between the SPE method and the official method in Japan (spectrophotometry after liquid–liquid extraction). The advantages of the SPE method are the short extraction times, lack of emulsions, and reduced consumption of organic solvents compared with the official method in Japan. The SPE method is considered to be useful for the screening of Phor a and Pyro a in health foods.
Determination of Maduramicin in Feedingstuffs and Premixtures by Liquid Chromatography: Development, Validation, and Interlaboratory Study
Authors: Jong Jacob De , Stoisser Bernd , Wagner Karl , Tomassen Marinka , Driessen Jaap , Hofmann Peter , Putzka Hans-Artur ,   Collaborators:, Antalick J P , Cowles J , Felgueiras I , Hofmann P , Johannsen F H , Putzka H A , Stepinska A , Stoisser; B , Thalmann A , van der Kamp H J , van Schalm K
Published: February 2020

A reversed-phase liquid chromatography method for determination of maduramicin in feedingstuffs and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was methanol. Maduramicin was detected at 520 nm after postcolumn derivatization with vanillin.
Single Laboratory Validation of a Method for Determination of Glucosamine in RawMaterials and Dietary Supplements Containing Glucosamine Sulfate and/or Glucosamine Hydrochloride by High-Performance Liquid Chromatography with FMOC-Su Derivatization
Authors: Zhou Joseph ZiQi , Waszkuc Ted , Mohammed Felicia
Published: February 2020

Single laboratory validation of a method for determination of glucosamine in raw materials and dietary supplements containing glucosamine sulfate and/or glucosamine hydrochloride by with high-performance liquid chromatography FMOC-Su derivatization. Tests with 2 blank matrixes containing SAMe, vitamin C, citric acid, chondroitin sulfates, methylsulfonylmethane, lemon juice concentrate, and other potential interferents showed the method to be selective and specific. Eight calibration curves prepared over 7 working days indicated excellent reproducibility with the linear range at least over 2.0–150 μg/mL, and determination coefficients >0.9999. Average spike recovery from the blank matrix (n = 8 over 2 days) was 93.5, 99.4, and 100.4% at respective spike levels of 15, 100, and 150%, and from the sample matrix containing glucosamine (n = 3) was 99.9 and 102.8% at respective levels of 10 and 40%, with relative standard deviations <0.9%. The method was also applied to 12 various glucosamine finished products and raw materials. The stability tests confirmed that glucosamine–FMOC-Su derivative once formed is stable at room temperature for at least 5 days. Limit of quantitation was 1 μg/mL and limit of detection was 0.3 μg/mL. The method is ready to proceed for the collaborative study.
Evaluation of the Swab Test On Premises for Detection of Antimicrobial Residues in Bovine and Porcine Kidneys
Authors: Salisbury Craig D C
Published: February 2020

The effect of sample matrix on the sensitivity of the Swab Test On Premises (STOP) was evaluated for selected antimicrobials. Fluid was extracted from bovine and porcine kidneys, and fortified with known levels of drugs. Aqueous standards were also prepared at the same levels. An aliquot of the fortified fluid or water was pipeted onto a dry swab which was placed onto the surface of a STOP plate, and the plate was incubated as outlined in the test kit manual. Zones of bacterial growth inhibition were measured and recorded, and additional testing was performed with decreasing levels of drug until a minimum detectable level was determined. The effect of temperature on the sensitivity of the test was also evaluated by running samples in duplicate, one set at a nominal temperature of 28°C, and the second set at a nominal temperature of 32°C. Fortified bovine kidney fluid produced significantly larger zones than did porcine kidney fluid at both temperatures, but the mean zone sizes for fortified water were not significantly different from those of bovine or porcine kidney fluid at either temperature. For all 3 matrixes, than 32zones of inhibition were significantly larger at 28°C than 32°C.
A Multicommutated Flow System for Determination of Bismuth in Milk Shakes by Hydride Generation Atomic Fluorescence Spectrometry Incorporating On-Line Neutralization of Waste Effluent
Authors: Ventura-Gayete Josep F , Ródenas-Torralba Eva , Morales-Rubio Ángel , Garrigues Salvador , Guardia Miguel De La
Published: February 2020

A highly sensitive method was developed for determination of bismuth in milk shakes by multicommutation hydride generation atomic fluorescence spectrometry (HG-AFS) based on off-line sonication for 10 min with aqua regia 8% (v/v) and on-line waste treatment. The instrumentation and chemistry variables were studied in order to provide the best performance. The limit of detection in the original samples, established for a probability level of 99.6% (k = 3), was 1.67 ng/g Bi. The method provides a fast alternative in control analysis with a sampling throughput of 72 h as compared with 31 h obtained by the classical continuous measurement. Additionally, multicommutation reduces waste generation by a factor of 2.6. The consumption of sample, reductant, and blank, as compared with continuous mode HG-AFS, was reduced 9.6, 4.5, and 13.3 times, respectively. To confirm the accuracy of the method, recovery studies were performed, and excellent agreement between multicommutation and continuous measurement-based values was obtained. Application of the developed methodology for bismuth determination in milk shake samples from the Spanish market provided concentrations ranging from 4.2 to 15.0 ng/mL, and good comparability with data obtained by continuous measurements after microwave-assisted total digestion of samples for a 95% probability level and 12 degrees of freedom was found.