bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Nalidixic Acid by Fluorometry with Sodium Borohydride and Hydrogen Peroxide
Authors: Wang Mei-Lin , Chen Sheng-Chih , Lien Jin-Cherng , Kuo Sheng-Chu 
Published: February 2020

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

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

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

Abstract
A method was developed for determining residual sulfonamide antibacterials such as sulfamethazine (SMZ), sulfamonomethoxine (SMM), sulfadimethoxine (SDM), and sulfaquinoxaline (SQ) in eggs using liquid chromatography with a photodiode array detector. The spiked and blank samples were cleaned up by using an Ultrafree®-MC/PL centrifugal ultrafiltration unit. A Mightysil® RP-4 GP column and a mobile phase of 28% (v/v) ethanol–H2O with a photodiode array detector were used for the determination. Average recoveries from eggs spiked with each drug at 0.1, 0.2, 0.4, and 1.0 ppm were ≥80.9%, with relative standard deviations between 1.3 and 4.7%. The limits of quantitation were 0.060 ppm for SMZ, 0.045 for SMM, 0.044 for SDM, and 0.093 for SQ. The analysis of one sample required &lt;30 min and &lt;5 mL ethanol as solvent.
Simultaneous Quantitation of Aspergillus flavus/A. parasiticus and Aflatoxins in Peanuts
Authors: Dorner Joe W 
Published: February 2020

Abstract
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 &lt; 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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 (&gt;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

Abstract
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

Abstract
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

Abstract
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 &gt;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

Abstract
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 (&gt;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

Abstract
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

Abstract
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 (&lt;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

Abstract
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

Abstract
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

Abstract
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.