bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Fat, Protein, and Total Solids in Cheese by Near-Infrared Reflectance Spectroscopy
Authors: Rodriguez-Otero José Louis , Hermida Maria , Cepeda Alberto
Published: February 2020

Near-infrared reflectance (NIR) spectroscopy was used to analyze fat, protein, and total solids in cheese without any sample treatment. A set of 92 samples of cow’s milk cheese was used for instrument calibration by principal components analysis and modified partial least-square regression. The following statistical values were obtained: standard error of calibration (SEC) = 0.388 and squared correlation coefficient (R2) = 0.99 for fat, SEC = 0.397 and R2 = 0.98 for protein, and SEC = 0.412 and R2 = 0.99 for total solids. To validate the calibration, an independent set of 25 cheese samples of the same type was used. Standard errors of validation were 0.47,0.50, and 0.61 for fat, protein, and total solids, respectively, and hf for the regression of measurements by reference methods versus measurements by NIR spectroscopy was 0.98 for the 3 components.
Determination of Thiabendazole in Potatoes, Fruits, and Their Processed Products by Liquid Chromatography
Authors: Bushway Rodney J , Li Lei , Paradis Lance R , Perkins Lewis B
Published: February 2020

A liquid chromatographic method has been developed for analysis of the fungicide thiabendazole (TBZ) in fruits, potatoes, and their processed products. Extraction was performed in a 50 mL polyethylene conical centrifuge tube with a basic solution. TBZ was partitioned (into methylene chloride with a polytron. No further cleanup was needed. Separation was carried out on a 5 μm Ultracarb 30 ODS column with fluorescent detection, excitation at 305 nm and emission at 345 nm. Total analysis time including extraction was 25 min per sample. Recoveries ranged from 77 to 135%. Average percent recovery for all sample types spiked from 5 ppb to 387 ppm was 94% with a coefficient of variation (CV) of 11%. Overall intra-assay CVs varied from 1.8 to 23%, and interassay CVs ranged from 1.8 to 15%. Of 194 commercial samples analyzed for TBZ, 129 were positive. TBZ in positive samples ranged from 1.1 ppb to 72.5 ppm. The limit of quantitation varied from 2.5 ppb for juices, 2.5 ppb for fruits and potatoes, and 4.5 ppb for bulk concentrates. Detection limits were 1.0 ppb for juice, fruits, and potatoes and 2 ppb for bulk concentrates. TBZ levels in the positive samples were corroborated by immunoassay.
Liquid Chromatographic Determination of Bromide Ion in Cereals, Fruit, Vegetables, and Blood with a Silver Electrode in an Electrochemical Detector System
Authors: Lindgren Bertil , Berglöf Tomas , Ramberg Åsa , Stepdmska Anna , Åkerblom Malin
Published: February 2020

A method is presented for rapid determination of bromide ion in commodities and blood by paired-ion liquid chromatography with electrochemical detection. The method involves extraction of samples with water and filtration. Blood is passed through a Sep-Pak C18 minicolumn. Recoveries are usually close to 100%, with satisfactory precision. The detection limit is 1 mg/kg. The method needs little labor and uses no noxious solvents or reagents.
Liquid Chromatographic Determination of Simazine, Atrazine, and Propazine Residues in Catfish
Authors: Holland David C , Munns Robert K , Roybal José E , Hurlbut Jeffrey A , Long Austin R
Published: February 2020

A liquid chromatographic (LC) method is described for the simultaneous determination of the triazine herbicides, simazine (SIM), atrazine (ATZ), and propazine (PRO) in the 12.5–100 ppb range in catfish. The herbicides are extracted from catfish homogenates with ethyl acetate, followed by solvent partitioning between acetonitrile and petroleum ether and additional cleanup on a C18 cartridge. A Supelcosil LC-18-DB column is used for LC separation, and UV determination is at 220 nm. The isocratic mobile phase is a mixture of methanol, acetonitrile, and water. Mean recoveries from catfish were 88.7, 96.9, and 91.7%; standard deviations were 6.84,7.78, and 6.26%; and coefficients of variation were 7.72,8.03, and 6.82% for SIM, ATZ, and PRO, respectively.
Liquid Chromatographic Determination of Furazolidone in Swine Serum and Avian Egg
Authors: Yosheda Kenichi , Kondo Fusao
Published: February 2020

A rapid, simple, and accurate method for determination of furazolidone (FZ) in swine serum and avian egg using liquid chromatography (LC) with a 358 nm ultraviolet-visible spectrophotometric detector is described. After liquid–liquid extraction of sample with ethyl acetate using Extrelut-3, the extract is evaporated, redissolved in 40% acetonitrile, and injected directly into the chromatograph. The antibiotic can be analyzed within 30 min. Withinday recoveries for swine serum and avian egg spiked with FZ at 1 ppm were 90.0 and 88.1%, respectively, with coefficients of variation of 3.52 and 3.88%, respectively. Between days recoveries for the 1 ppm samples were 87.2 and 87.0%, with coefficients of variation of 3.10 and 4.29%, respectively. Determination of FZ also was performed by LC/mass spectrometry (MS) with an atmosphericpressure chemical-ionization interface (APCI) system. The LC/MS–APCI system is more applicable for qualitative analysis than quantitative analysis because the drug detection limit (about 0.1 μg/mL) is almost the same as that of the LC–UV detector.
Estimation of Azadirachtin-A Content of Emulsifiable and Solution Concentrates of Neem
Authors: Azam Mohibb E , Rengasamy Seem , Parmar Balraj S
Published: February 2020

A column chromatographic cleanup method to remove aliphatic and aromatic solvent components and different surfactants present in formulated neem was developed. A glass column containing silica gel (60–120 British Standard Sieve) and 250 mL hexane–acetone (6 + 4) was used. Impurities interfering in the region of the azadirachtin-A peak were removed by fractional elution. Recovery of azadirachtin-A was greater than 81%.
U.S. Food and Drug Administration Pesticide Program: Incidence/Level Monitoring of Domestic and Imported Pears and Tomatoes
Authors: Roy Ronald R , Albert Richard H , Wilson Patrick , Laski Ronald R , Roberts James I , Hoffmann Terry J , Bong Rodney L , Bohannon Byron O , Yess Norma J
Published: February 2020

In 1992–1993, the U.S. Food and Drug Administration (FDA) conducted a statistically based study of pesticide residues in domestic and imported pears and tomatoes. For pears, 710 domestic and 949 imported samples were collected and analyzed; 79% of the domestic and 72% of the imported samples had detectable residues. Thiabendazole, a fungicide with postharvest uses, was found with greatest frequency in both groups of pears. Four domestic and 12 imported samples contained violative residues, mainly of pesticides for which there are no U.S. tolerances on pears. The statistically weighted (by shipment size) violation rates for domestic and imported pears were 1.0 and 0.9%, respectively. For tomatoes, 1219 domestic and 144 imported samples were collected and analyzed; 84% of the domestic and 91% of the imported samples had detectable residues. Methamidophos, an insecticide, had the greatest frequency of occurrence in both groups of tomatoes. Thirtythree domestic and 5 imported samples were violative, nearly all the result of acephate use, for which there is no U.S. tolerance on tomatoes. The statistically weighted violation rates for domestic and imported tomatoes were 1.9 and 7.0%, respectively. The statistically weighted violation rates calculated for domestic and imported pears and domestic tomatoes in this study were lower than those observed under FDA’s regulatory monitoring in recent years. The violation rate for imported tomatoes was somewhat higher under statistical monitoring than under regulatory monitoring. The results of the statistically based study show that, as in regulatory monitoring, the levels of pesticide residues found are generally well below U.S. tolerances.
Daily Intakes of THbutyltin and THphenyltin Compounds from Meals
Authors: Tsuda Taizo , Inoue Tomohiro , Kojima Mihoko , Aoki Shigeru
Published: February 2020

Daily intakes of tributyltin (TBT) and triphenyltin (TPT) compounds from meals in Shiga Prefecture, Japan, were investigated by 2 methods. Daily intakes of TBT and TPT by the duplicate portion method were, respectively, 4.7 and 0.7 μg in 1991 and 2.2 and 0.7 μg in 1992. Those by the market basket method were, respectively, 6.9 and 5.4 μg in 1991 and 6.7 and 1.3 μg in 1992. Daily intakes of TBT and TPT by the market basket method were higher than those by the duplicate portion method. These values were considerably lower than acceptable daily intakes of 80 μg/50 kg body weight specified by the Welfare Ministry of Japan for bis(tri-n-butyltin) oxide and of 25 μg/50 kg body weight specified by the Food and Agriculture Organization/ World Health Organization for TPT.
Cryopreservation of Bacterial Vegetative Cells Used in Antibiotic Assay
Authors: Reamer Richard , Dey B R , Thaker Nitin
Published: February 2020

A long-term cryopreservation study of vegetative cells of Micrococcus lutea ATCC 9341a, Micrococcus lutea ATCC 15957, and Staphylococcus epidermidis ATCC 12228 cells, used in our antibiotic bioassay procedure, was conducted. The cryoprotective abilities of 1% methylcellulose solution and a 15% glycerol solution at −14°C were determined. More organisms remained viable in 1% methylcellulose than in 15% glycerol. Overall survival of Staphylococcus epidermidis ATCC 12228 after 365 days was 1.5 logs lower than the other 2 organisms. The sensitivity and the resistance of the preserved organisms to various antibiotics did not change: The methodology is simple and inexpensive, saves analytical time, and avoids risk of contamination and sudden loss of a well-characterized culture.
Planar Chromatography for Screening of Ivermectin Residues in Swine and Cattle Tissues
Authors: Abjean Jean-Pierre , Gaugain Murielle
Published: February 2020

A method was developed for qualitative detection of ivermectin residues. It involves extraction of 1 g tissue sample with 5 mL acetonitrile and C18 solid-phase extraction. After derivatization with tri-fluoroacetic anhydride, the extract is purified again on the same but previously reconditioned C18 column. The eluate is evaporated, and the residue is diluted in methanol. The method allows detection of residues in swine and cattle meat, liver, and fat at levels as low as 5 μg/kg.
Effects of Drying Temperature on Fumonisin Recovery From Feeds
Authors: Bordson Gary O , Meerdink Gavin L , Bauer Karla J , Tumbleson Mike E
Published: February 2020

A number of corn and feed samples submitted for fumonisin analysis contain high levels of moisture. The high moisture content can interfere with grinding during sample preparation and, if samples are held at room temperature, may promote fungal, bacterial, and/or other microbial growth. To inhibit possible sample deterioration, wet corn and feed samples routinely are stored in a freezer. Prior to grinding, the sample, or a representative portion, is dried. Using a fumonisin-positive, rain-soaked, pelleted mixed feed, we found that prolonged drying at temperatures above 50°C results in decreased fumonisin recoveries. Therefore, we carried out a study to assess the effect of drying times and temperatures on recoveries of fumonisins FB1 and FB2. A fumonisin-positive corn sample and the pelleted mixed feed were dried for various periods up to 24 h at 30°, 50°, or 110°C. Duplicate samples were dried for 0, 0.25, 0.5, 1, 2, 4, 8, or 24 h at each temperature. Samples were extracted with solvent, and an aliquot of each extract was cleaned up with Cie Sep-Pak cartridges. Extracts were derivatized with fluorescamine and analyzed by liquid chromatography with fluorescence detection. During the 24 h drying period, recoveries of fumonisins FB1 and FB2 from samples dried at 110°C exhibited a nonlinear decrease. Recoveries from samples dried at 30° and 50°C showed no real change.
Potentiometric Determination of Cyanoguanidine and Analysis of Its Unique Titration Curve
Authors: Yoshevaga Tetsutaro , Koga Masaaki , Kawano Kentaro
Published: February 2020

Cyanoguanidine (CG) is an important starting or intermediate material for many synthetic compounds and is useful as a fertilizer. Calcium cyanamide (CaCN2 fertilizer easily hydrolyzes to cyanamide (NH2CN; Cy), and Cy dimerizes into CG under weakly alkaline condition. In the present work, CG was determined potentiometrically with a silver sulfide membrane-type ion-selective electrode. A unique titration curve was obtained when a sample solution of CG and picrate (or picric acid) at a picrate/CG molar ratio of 1.5 or more was titrated with silver nitrate standard solution. The curve showed a rapid potential drop at half-equivalence point, and by using this point, accurate and precise values of CG were obtained (recovery, 99.8%; relative standard deviation, 0.1%, n = 10). Even at a wide pH range (1.7 to 10.2), CG was determined accurately. The presence of Cy scarcely interfered. CG (400 μmol) was detected with a molar ratio of 190. With the standard addition method, CG (400 μmol) was determined even with a Cy/CG molar ratio of 2500. The lowest detection limit was 4 × 10−3 mol/L (40 μmol absolute).
Determination of Tetracycline Residues in Bovine Milk, Serum, and Urine by Capillary Electrophoresis
Authors: Chen Chao-Ling , Gu Xuelin
Published: February 2020

A method was developed for simultaneous determination of oxytetracycline (OTC), chlortetracycline, tetracycline, and doxycycline levels in cow milk, serum, and urine by capillary electrophoresis (CE). The tetracyclines (TCs) were extracted specifically with a metal-chelating affinity column. Extracts were then applied to C18 cartridges treated with dimethyldichlorosilane, and the TCs were eluted with ethanol. Salt-free sample residues were run on CE with a diode array detector at 370 nm. A 50 cm × 75 μm uncoated capillary at 15 kV and 23°C was used to separate the TCs. The run buffer contained 10 mM sodium dodecyl sulfate, 50 mM borate, and 50 mM phosphate, pH 8.5. TC peaks were identified by migration times, coinjection of standards, and diode array spectra. Limits of detection for TCs were 1.3-5.3 ng/mL, and limits of quantitation were 1.7-8.7 ng/mL in cow fluid samples. OTC appeared consistently at 13.3-13.4 min in milk, serum, and urine samples from a cow treated with OTC. OTC was further identified by coinjection of OTC standard and OTC diode array spectra. The CE method can be used to simultaneously determine 4 TC residues at low parts-per-billion levels.
Modification of AOAC Multiresidue Method for Determination of Synthetic Pyrethroid Residues in Fruits, Vegetables, and Grains. Part I: Acetonitrile Extraction System and Optimization of Florisil Cleanup and Gas Chromatography
Authors: Pang Guo-Fang , Chao Yan-Zhong , Fan Chun-Lin , Zhang Jin-Jie , Li Xue-Min , Zhao Tie-Sheng
Published: February 2020

We present a multiresidue method for determination of synthetic pyrethroids in fruits, vegetables, and grains. The method is a modification of AOAC Method 970.52. Residues are extracted with acetonitrile (for fruits and vegetables) or acetonitrile–water (2 + 1) (for grains) and then transferred to hexane. Coextractives are removed by acetonitrile partitioning and open-column chromatography with deactivated Florisil. The final extract is analyzed by gas chromatography with electron capture detection (GC–ECD). An HP-17 wide-bore column is used to determine the total isomeric content of each insecticide, and a DB-5 narrow-bore column is used to determine the individual isomeric contents of each insecticide. The method was used to recover 8 pyrethroids (biphenthrin, fenpropathrin, cyhalothrin, permethrin, cypermethrin, fluvalinate, fenvalerate, and deltamethrin) spiked at 0.01–4.0 mg/kg in 20 crops (apple, pear, peach, banana, grape, strawberry, potato, tomato, cucumber, pepper, cabbage, carrot, celery, polished rice, wheat, green gram, buckwheat, sorghum, maize, and barley). Recoveries of the 8 pyrethroid insecticides in 6 crops ranged from 83.8 to 112.8%, with a coefficient of variation (CV) of 2.00 to 12.09% for the narrow- bore capillary GC (n = 6) and from 82.8 to 106.4%, CV = 2.93–12.19%, for the wide-bore capillary GC (n = 6). The minimum detectable levels of 0.004–0.028 mg/kg (for fruits and vegetables) or 0.01–0.08 mg/kg (for grains) for the 8 pyrethroids are easy to detect.
Determination of Chromium and Molybdenum in Medical Foods by Graphite Furnace Atomic Absorption Spectrophotometry
Authors: Phifer Edwin C
Published: February 2020

Graphite furnace atomic absorption spectrophotometry was used to determine chromium and molybdenum in 7 medical foods from 5 manufacturers. Linear standard curves were obtained for both elements for concentrations between 5 and 25 ng/mL. Detection limits were 0.24 ng/mL for Cr and 0.67 ng/mL for Mo. Characteristic masses were 3.1 and 14.7 pg for Cr and Mo, respectively. No difference was detected between wet and dry ashing methods, and dry ashing was used to complete the study. The method was validated by assaying various National Institute of Standards and Technology standard reference materials. Analysis of these products for Cr and Mo were within certified values. One product was evaluated by this method for reproducibility (n = 5). Relative standard deviations were 6.8 and 4.8% for Cr and Mo, respectively. This product contained 0.31 ± 0.02 μg Cr/g and 0.63 ± 0.03 μg Mo/g. The remaining products contained 0.09–1.28 μg Cr/g and 0.07–2.3 μg Mo/g. Mean recovery values were 98 ± 14% (n = 14) for Cr at spike levels of 0.20–1.89 μg/g and 102 ± 24% (n = 10) for Mo at spike levels of 0.30–1.89 μg/g.
Determination of Glyphosate and Its Metabolite, (Aminomethyl)phosphonic Acid, in River Water
Authors: Mogadati Paul S , Louis Judith B , Rosen Joseph D
Published: February 2020

A procedure for extracting glyphosate and its meta bolite, (aminomethyl)phosphonic acid, from river water and for determining these 2 compounds by gas chromatography/ion trap mass spectrometry is described. Both compounds were extracted with Bio-Rad AG 1-X8 anion-exchange resin (formate form) prior to derivatization with a mixture of trifluoroacetic anhydride and trifluoroethanol. Limits of detection for glyphosate and its metabolite were 1 ppb even when as little as 10 mL water was analyzed. Recoveries of both compounds from river water fortified at 50 ppb were >90%.
Determination of Dietary Fiber and Carbohydrate Composition of Foods by a Modified Version of the Englyst Method
Authors: Lichon Michael J , James Keith W
Published: February 2020

A modified version of the Englyst procedure for determination of dietary fiber and carbohydrate fractions of foods is described. The method is based on hydrolysis of separated fractions and capillary gas chromatographic (GC) analysis of derivatized monomer sugars, UV photometry of uronic acids, gravimetric determination of residue, and analysis of nitrogen content of the residue by using a C, H,N elemental analyzer. Modifications of fractiona tion, derivatization, and GC procedures are dis cussed. Rigorous sample preparation is required for reproducibility of 200 mg test portions. Contami nants interfering with chromatography must be minimized. Results for reference samples (wheat bran and Buerre Bose pears) and white and wholemeal bread agree with literature values.
Monitoring of Pesticide Residues in Fresh Vegetables, Fruits, and Other Selected Food Items in Belgium, 1991-1993
Authors: Dejonckheere Willy , Steurbaut Walter , Drieghe Sabine , Verstraeten Roland , Braeckman Hans
Published: February 2020

To estimate the exposure of the Belgian population to food contaminated with pesticide residues andto determine what pesticides people are actually consuming, a total diet study—individual approach—was performed. Fourteen kinds of fruits, 22 kinds of vegetables, and 7 other food items (coffee, drinking water, rice, tea, wine, bran, and wheat flour) were selected as major representatives of the Belgian diet. During the 2 years of study (April 1991- March 1993), about 3698 samples were analyzed and 21 163 analyses were performed. The first part of this study demonstrates that no residues are found in 31.3% of leafy vegetables, 72.3% of other vegetables, 51.4% of fruits, and 67.2% of other samples. In particular cases, some critical situations still exist, especially for leafy vegetables. Also, contamination of foreign samples is not easy to determine, because origins are not always traceable.
Method Development in Supercritical Fluid Extraction
Authors: McNally Mary Ellen P
Published: February 2020

When using supercritical fluid extraction (SFE), a variety of chemical and physical parameter interactions must be considered in developing a sample preparation method. Those interactions, especially for an analyst who is unfamiliar with the properties and potentials of supercritical fluids, can make routine analytical method development quite rigorous. This paper is meant as a guide for a novice user of SFE. It illustrates a logical scheme to consider when removing an analyte from a difficult matrix.
Robotic Automated Analysis of Foods for Aflatoxin
Authors: Carman Allen S , Kuan Shia S , Ware George M , Umrigar Pesi P , Miller Kenneth V , Guerrero Humberto G
Published: February 2020

Immunoaffinity column-based sample preparation procedures for determination of aflatoxins B1, B2,G1, and G2 in several food matrixes and aflatoxin M1 in milk have been automated by using flexible automation, or robotics. Components used to assemble the system were purchased commercially or developed and built in-house. A liquid-level sensor developed in-house to assist elution of the immunoaffinity column is described. After immunoaf finity column cleanup, aflatoxins are separated by reversed-phase liquid chromatography and determined by fluorescence without derivatization.Mean recoveries of aflatoxins B1, B2, and G1 added to corn and nuts at 9-36 ng/g total aflatoxins were >85% (coefficient of variation [CV] = 16%). Recoveries of aflatoxin G2 averaged 50% (CV = 28%). Recoveries of aflatoxin M1 added to milk at 0.120.50 ng/mL averaged 78% (CV = 19%). The ability of the automated system to reproduce its results is demonstrated by the fact that the CV of replicate assays is generally better than 10%. Comparability between the automated procedure and the AOAC official method is demonstrated.
Variability Associated with Analytical Methods Used To Measure Aflatoxin in Agricultural Commodities
Authors: Whitaker Thomas , Horwitz William , Albert Richard , Nesheim Stanley
Published: February 2020

A total of 1019 analytical precision estimates obtained from method-performance (collaborative) studies for mycotoxins published through 1991 were sortedby type of variance measurement, type of analytical method, and type of agricultural commodity. Precision estimates for total aflatoxin were sorted into 2 precision measurements (among-labo ratories and with in-laboratory), 3 analytical methods (thin-layer chromatography [TLC], liquid chromatography [LC], and enzyme-linked immunosorbent assay [ELISA]), and 11 agricultural commodities. Sufficient data existed to study the analytical variability (precision) associated with 36 sorted combinations (of a possible 66). In all but one combination (within-laboratory, barley, and TLC), the variance (V) was a function of totalafla- toxin concentration (C). A power function of the form V = aCb, where a and b are constants, describes the relationship between variance and aflatoxin concentration. The coefficients a and b were determined from regression analysis. When results were pooled across all agricultural commodities, LC had the lowest analytical variability while ELISA had the highest. For a given method, among-labora tories variability was approximately double the with in-laboratory variability. These analytical variability estimates can be coupled with previously determined variability estimates of sampling and sample preparation to determine the performance associated with specific test procedures used to inspect agricultural commodities for aflatoxin.
Quantitative Analysis of 2-Aminoacetophenone in Off-Flavored Wines by Stable Isotope Dilution Assay
Authors: Dollmann Bettina , Wichmann Dominicus , Schmitt Alfred , Koehler Hans , Schreier Peter
Published: February 2020

Isotope dilution analysis was used to quantitate 2- aminoacetophenone in wines exhibiting the so- called untypical aging off-flavor. d3-Aminoacetophe- none was synthesized and used as isotopomeric internal standard. The method of quantitation was verified by several model experiments. In the off-flavored wines studied, amounts of 2-aminoacetophe none ranging from 0.7 to 12.8 μg/L were determined.
Gas Chromatographic Determination of Chlorothalonil in Leaves and Roots of Scrophularia and in Soil
Authors: Zhao Lan , Fan De-Fang
Published: February 2020

A gas chromatographic method is described for determination of chlorothalonil residues in leaves and roots of Scrophularia and in soil. Samples were extracted with acetone and cleaned up on a Florisil column. Chlorothalonil residues are chromatographed directly on a glass column of 1.5% OV-17 and 2% QF-1 coated on 80-100 mesh Chromosorb W (HP) support and measured with a 63Ni electron capture detector. Detection limits are 0.001 ppm for leaf, 0.005 ppm for root, and 0.001 ppm for soil.
Simultaneous Determination of Ascorbic, Dehydroascorbic, Isoascorbic, and Dehydroisoascorbic Acids in Meat-Based Food Products by Liquid Chromatography with Postcolumn Fluorescence Detection: A Method Extension
Authors: Ali M Sher , Phillippo Evan T
Published: February 2020

A simple and rapid liquid chromatographic (LC) method for determining ascorbic, dehydroascorbic, isoascorbic, and dehydroisoascorbic acids in mostly single-component food products was evaluated for use in analysis of multicomponent meatbased food products such as TV dinners. Groundbeef samples were used as blanks for repeatability studies. Samples were fortified with 5,10,20, and 40 ppm of mixed standards of ascorbic acid and isoascorbic acid. Means of 12 recoveries at 4 levels of fortification were 102.5 and 83.5%, respectively, for ascorbic acid and isoascorbic acid, with coefficients of variation of 6.7 and 15.2%, respectively. TV dinner products (21 samples) from a local grocery store were analyzed for vitamin C content. Samples prepared with a commercial food processor and a food grinder were compared. The commercial food processor was more capable than the food grinder in producing a homogeneous sample, which is critical to the method.
Simple HNMR Spectroscopic Method for Assay of Salts of the Contrast Agent Diatrizoate in Commercial Solutions
Authors: Hanna George M , Lau-Cam Cesar A
Published: February 2020

A simple, accurate, and specific 1H NMR spectroscopic method was developed for the assay of diatrizoate meglumine or the combination diatrizoate meglumine and diatrizoate sodium in commercial solutions for injection. A mixture of injectable solution and sodium acetate, the internal standard, was diluted with D20 and the 1H NMR spectrum of the solution was obtained. Two approaches were used to calculate the drug content, based on the integral values for the -N-CO-CH3 protons of diatrizoic acid at 2.23 ppm, the N-CH3 protons of meglumine at 2.73 ppm, and the CH3-CO-protons of sodium acetate at 1.9 ppm. Recoveries (mean ± standard deviation) of diatrizoic acid and meglumine from 10 synthetic mixtures of various amounts of these compounds with a fixed amount of internal standard were 100.3 ±; 0.55% and 100.1 ± 0.98%, respectively. In addition to providing a direct means of simultaneously assaying diatrizoic acid and meglumine, the proposed NMR method can also be used to identify diatrizoate meglumine and each of its molecular components.
Determination of Ceftiofur in Bovine Milk by Liquid Chromatography
Authors: Mcneilly Patrick J , Reeves Valerie B , Deveau E J Ian
Published: February 2020

A liquid chromatographic procedure is described for determination of ceftiofur (CEF) residues in milk. Milk samples were diluted with ammonium acetate solution and extracted on a C18 solid-phase extraction (SPE) column. After the analyte was eluted from the SPE column with methanol, extract volumes were reduced under nitrogen, diluted to 2.0 mL with acetate buffer, and filtered. CEF was determined after separation of milk components by reversed-phase chromatography with UV detection at 293 nm. Recoveries of CEF from bovine milk fortified at 25,50, and 100 ppb were 86.1,90.8, and 92.0%, respectively, with coefficients of variation (CVs) of 6.4, 7.3, and 3.9%, respectively. Values of CEF obtained from analysis of milk containing 2 levels of biologically incurred residues were 26.1 and 67.3 ppb with CVs of 3.8 and 4.4%, respectively. The limits of detection and quantitation were estimated to be 4 and 7 ppb, respectively.
Evaluation of a Rapid and Automated Enzyme-Linked Fluorescent Immunoassay for Detecting Escherichia coli Serogroup 0157 in Cheese
Authors: Cohen Alice E , Kerdahi Khalil F
Published: February 2020

The Vitek Immunodiagnostic Assay System (VIDAS) for Escherichia coli 0157, a rapid and fully automated test, was evaluated for use in detecting the foodborne pathogen E. coli 0157:H7 in soft, semisoft, and hard cheeses. Sixty-five cheese samples were artificially contaminated at low (2-4 colonyforming units [cfu]/25 g) and high (7-10 cfu/25 g) levels with one of 2 strains of enterohemorrhagic E. coli 0157:H7. Contamination at high levels was detected in all cheeses by VIDAS, whereas in 5 cheeses (7.7%) inoculated at low levels, contamination was not detected. In 15 additional cheeses inoculated with cold-stressed cells, both VIDAS and the Bacteriological Analytical Manual cultural assay detected all high and low levels of contamination. No false positives or interference from product background fluorescence was encountered in any of the cheeses tested by VIDAS.
Detection of Added Beet Sugar in Concentrated and Single Strength Fruit Juices by Deuterium Nuclear Magnetic Resonance (SNIF-NMR Method): Collaborative Study
Authors: Martin Gilles G , Wood Roger , Martin Gérard J ,   Collaborators:, Bigwood T , Blanch-Cortes A I , Cisero M , Cristoph N , Estoueigt M J , Guillou C , Hermann A , le Leuch A , Lindler P , Moussa I , Pavanello F , Reniero F , Serrini G , Wittkowski R , Zhang B
Published: February 2020

A collaborative study of the site-specific natural isotope fractionation-nuclear magnetic resonance (SNIF-NMR) method for detecting added beet sugar in fruit juices is reported. This method is complementary to the stable carbon isotope ratio analysis (SCIRA) (AOAC Official Methods 981.09 and 982.21), which can detect sugars derived from plants exhibiting C4 metabolism (corn and sugarcane). It is based on the fact that the deuterium content at specific positions of the sugar molecules is higher in fruit sugars than in beet sugar. The fruit juices are fermented, and the alcohol is distilled with a quantitative yield and analyzed with a highfield NMR spectrometer fitted with a deuterium probe and fluorine lock. The proportion of ethanol molecules monodeuterated on the methyl site is recorded. This parameter (D/H)i is lowered when beet sugar is added to a fruit juice or concentrate. The precision of that method for measuring (D/H)i was observed to be similar to that of other isotope ratio methods: sr values ranged from 0.19 to 0.25 ppm and SR values varied between 0.21 and 0.37 ppm. An excellent correlation was observed between the percentage of added beet sugar and the (D/H)i isotope ratio measured in this collaborative study. Consequently, all samples in which beet sugar was added were found to have a (D/H)i isotope ratio significantly below the normal value for authentic juice or concentrate of that fruit. The SNIF-NMR method for detection of added beet sugar in fruit juices has been adopted by AOAC INTERNATIONAL.
Use of Solid-Phase Extraction Disks for Analysis of Moderately Polar and Nonpolar Pesticides in High-Moisture Foods
Authors: Casanova John A
Published: February 2020

This study investigated the use of solid-phase extraction (SPE) disks in analysis of high-moisture (<2% fat) foods for organophosphorus and organochlorinated pesticides with low (<25 mg/mL) water solubilities. Five representative foods were each spiked with one of 18 pesticides at 2 levels. Gas chromatography with flame photometric and electrolytic conductivity detection was used to quantitate organophosphates and organochlorinated pesticides, respectively. Essentially complete recoveries (≥80%) suggest that use of SPE disks can complement traditional liquid-liquid extraction procedures.
Liquid Chromatographic Determination of Progestogens in Animal Fat
Authors: Andresen Michael T , Fesser Adrian C E
Published: February 2020

A liquid chromatographic method was developed for determination of 3 progestogens�melengestrol acetate, megestrol acetate, and chlormadinone acetate� found in edible tissue at concentrations between 10 and 1000 ppb. These progestogens are commonly used as feed additives to control herd estrus and to improve feed efficiency. Rendered fat was extracted with acetonitrile, washed with hexane, and dried. The remaining lipids were saponified with sodium hydroxide and precipitated with magnesium chloride. The progestogens were extracted from the basic solution with hexane, dried, and cleaned up on a cyanopropyl solid-phase extraction column in the normal-phase mode. The eluate was dried and reconstituted with acetonitrilewater (7 + 3, v/v). Chromatography was performed on a 5 μm high-carbon load C18 column with acetonitrile- water (7 + 3, v/v) at 1 mL/min and UV detection at 291 nm. Recoveries from fortified samples ranged from 84 to 116%. The limit of quantitation was 10 ppb for both beef and pork. The detection limit was 3 ppb.
Determination of Avermectin Bi in Biological Samples by Immunoaffinity Column Cleanup and Liquid Chromatography with UV Detection
Authors: Li Junsuo , Qian Chuanfan
Published: February 2020

A simple and specific procedure for determination of avermectin B1 in biological samples is described. A specific anti-avermectin B1 immunosorbent was developed. Avermectin B1 was extracted from cattle plasma, cattle meat, and pear samples. The extracts were cleaned up on a solid-phase extraction column (C18) and an immunoaffinity column. Avermectin B1 was determined by reversedphase liquid chromatography with UV detection at 245 nm. Recoveries of avermectin Bi from samples spiked at levels of 6 and 60 parts per billion (ppb) ranged from 80 to 86%, with coefficients of variation of 5-14%. The limit of detection was 2 ppb. The procedure provides a simple and sensitive method for monitoring avermectin B1 residues in biological matrixes.
TECRA Listeria Visual Immunoassay (TLVIA) for Detection of Listeria in Foods: Collaborative Study
Authors: Knight Michael T , Newman Melissa C , Benzinger M Joseph , Agin James R , Ash Megan , Sims Paul , Hughes Denise ,   Collaborators:, Arling V , Brock G , Bronstein A , Brooks R , Bucknavage M , Cirigliano M , Coles C , Farber J , Fisher B , George N , Heisick J , lannucci M , Koeritzer B , Lovett S , Mays J , McNally S , Menning C , Nelson T , Neufang K , Neuman S , O’Brien J , Rude R , Rudowski J , Singleton E , Sirivicha S , Turner S , VanderMeer J , Warburton D , Young S
Published: February 2020

A collaborative study involving 26 laboratories and 5 food types was performed to compare the TECRA Listeria Visual Immunoassay (TLVIA) with standard culture methods. Three foods (lettuce, ice cream, and fish fillets), under the jurisdiction of the U.S. Food and Drug Administration, and 2 foods (cooked chicken and cooked ground turkey), under the jurisdiction of the U.S. Department of Agriculture, were used to determine the effectiveness of the TLVIA. Of the 900 samples tested, 300 were inoculated with low levels (1-5 cells/25 g) of Listeria spp. and 300 were inoculated with high levels of Listeria spp. (10-50 cells/25 g). Method agreement between the conventional culture methods and TLVIA (visual) was 94.7%. Method agreement between the conventional culture methods and TLVIA (reader) was 93.6%. The colorimetric polyclonal enzyme immunoassay (TLVIA) for detection of Listeria in foods has been adopted first action by AOAC INTERNATIONAL.
Analysis of IHchothecene Mycotoxins in Contaminated Grains by Gas Chromatography/Matrix Isolation/Fourier Transform Infrared Spectroscopy and Gas Chromatography/Mass Spectrometry
Authors: Mossoba Magdi M , Adams Sarah , Roach John A G , Trucksess Mary W
Published: February 2020

Gas chromatography/matrix isolation/Fourier transform infrared (GC/MI/FTIR) spectroscopy and GC/mass spectrometry (MS) were used to confirm the identities of trimethylsilyl (TMS) derivatives of trichothecene mycotoxins in naturally contaminated grains. Infrared spectral bands observed in the fingerprint region were unique for 10 trichothecene standards. Characteristic absorption bands were observed for the ester (near 1750 cm-1) and ketone (near 1700 cm-1) carbonyl stretching vibrations, the acetate CH3 symmetric bend (1370 cm-1), the epoxide ring (1262 cm-1), the trimethylsilyl CH3 in-plane deformation (1253 cm-1), the ester (O)C-O asymmetric stretching vibration (near 1244 cm-1), and several other bands including intense features due to the TMS function. Infrared bands observed under cryogenic matrix isolation conditions were compared with those found at room temperature in a potassium bromide matrix for 5 of these standards. Identities of deoxynivalenol (DON) from barley and mixed feed, nivalenol from wheat and barley, and DON and fusarenon-x from sweet corn were confirmed by comparison of their infrared spectral bands with those of standards. The identity of DON in the same test samples of sweet corn was confirmed further by GC/MS. GC/MS was also used to quantitate the levels of DON (67-455 ppm) in sweet corn test samples.
Anatoxin B1 in Common Egyptian Foods
Authors: Selim Mustafa I , Popendorf William , Ibrahim Mahmoud S , Sharkawy Saleh El , Kashory El Syeda El
Published: February 2020

Samples of common Egyptian foods (17 nuts and seeds, 10 spices, 31 herbs and medicinal plants, 12 dried vegetables, and 28 cereal grains) were collected from markets in Cairo and Giza. A portion of each sample was extracted with chloroform, and the concentrated extract was cleaned by passing through a silica gel column. Aflatoxin Bi was determined by reversed-phase liquid chromatography with UV detection. The highest prevalence of aflatoxin B1 was in nuts and seeds (82%), followed by spices (40%), herbs and medicinal plants (29%), dried vegetables (25%), and cereal grains (21 %). The highest mean concentration of aflatoxin B1 was in herb and medicinal plants (49 ppb), followed by cereals (36 ppb), spices (25 ppb), nuts and seeds (24 ppb), and dried vegetables (20 ppb). Among nuts and seeds, the prevalence of aflatoxin B1 was highest (100%) in watermelon seeds, inshell peanuts, and unshelled peanuts. The lowest prevalence and concentrations were in hommos (garbanzo beans). The highest concentrations of aflatoxin B1 were detected in foods that had no potential for field contamination but required drying during processing and storage, such as pomegranate peel, watermelon seeds, and molokhia.
Comparison of Mouse Bioassay and Sodium Channel Cytotoxicity Assay for Detecting Paralytic Shellfish Poisoning Toxins in Shellfish Extracts
Authors: Truman Penelope , Lake Robin J
Published: February 2020

A neuroblastoma cell culture assay was used to analyze shellfish extracts for presence of paralytic shellfish poisoning toxins (saxitoxins). Results were compared with mouse bioassays performed as part of a screening program for shellfish toxins in New Zealand. Twenty-nine samples gave negative results in both assays. Fifty-seven samples gave positive results in at least one assay. The correlation between the assays for saxitoxin equivalent levels in shellfish was 0.867. In spiking studies on shellfish extracts, the neuroblastoma assay showed a good response to added saxitoxin. Although these results support use of the neuroblastoma assay as a screening procedure for shellfish toxicity, results close to regulatory limits should be confirmed by mouse bioassay.
Determination and Confirmation of Identities of Flumequine and Nalidixic, Oxolinic, and Piromidic Acids in Salmon and Shrimp
Authors: Pfenning Allen P , Munns Robert K , Turnipseed Sherri B , Roybal José E , Holland David C , Long Austin R , Plakas Steven M
Published: February 2020

A previously published liquid chromatographic (LC) method for determining residues of flumequine (FLU) and nalidixic (NAL), oxolinic (OXO), and piromidic (PIR) acids in catfish tissue was applied to salmon and shrimp muscle. Identities of all 4 residues in salmon and shrimp were confirmed by gas chromatography/mass spectrometry (GC/MS). The tissue is homogenized with acetone, the acetone extract is defatted with hexane, and the quinolones are extracted into chloroform. The extract is further purified by first partitioning into base and then back-extracting from a solution acidified to pH 6.0. Analytes are determined by LC with simultaneous UV and fluorescence detection. Muscle tissue was fortified with each quinolone at 5,10,20,40, and 80 ng/g. Average recoveries and relative standard deviations (RSOs) for salmon, which represent an average of the 5 levels for each analyte, ranged from 75.9 to 90.8% and from 2.25 to 6.40%, respectively. Average recoveries and RSDs for shrimp ranged from 81.3 to 91.2% and from 7.34 to 10.7%, respectively. Identities of OXO, FLU, NAL, and PIR were confirmed in extracts of salmon and shrimp tissue fortified at 10 ng/g by determination of decarboxylated quinolones by GC/MS. Four diagnostic ions were monitored for OXO, FLU, and PIR, and 5 ions were monitored for NAL. All ion relative abundances were within 10% of those calculated for standard decarboxylated quinolones. Optimum conditions for decarboxylation and GC/MS confirmation are given.
Determination of Diphenoxylate Hydrochloride and Atropine Sulfate in Combination Drug Formulations by Liquid Chromatography
Authors: Lehr Gary J
Published: February 2020

An isocratic, reversed-phase liquid chromatographic (LC) method was developed for simultaneous determination of diphenoxylate hydrochloride (I) and atropine sulfate (II) in pharmaceutical products. Analysis is conducted on a Spherisorb CN column (5 µm), with a mobile phase consisting of 47% 0.001 M pentanesulfonic acid sodium salt monohydrate, 53% acetonitrile, and 0.1 % phosphoric acid. The detection wavelength is 220 nm. Tablets are extracted with acetonitrile–water (50 + 50). Oral solutions are determined directly after dilution. The method is validated for linearity, precision, system reproducibility, and accuracy. Recoveries at 80-120% of label claim ranged from 98.7 to 101.0% and from 99.6 to 102.5% for I and II, respectively. Results were linear (r > 0.9999) in the ranges 125–375 µg/mL and 1.25–3.75 µg/mL for I and II, respectively. Assay and content uniformity results for each ingredient, in both innovator products and generic formulations, are reported. Diphenoxylic acid, the principal degradation product and major metabolite of I, is separated and can be determined in tablets and oral solutions.
Immunoaffinity Column Cleanup and Liquid Chromatographic Method for Determining Ivermectin in Sheep Serum
Authors: Li Junsuo , Zhang Shiqin
Published: February 2020

A simple and sensitive method was developed for determining ivermectin in sheep serum. The sample is cleaned up on an immunoaffinity column and determined by liquid chromatography with detection at 245 nm. Recoveries ranged from 90.3 to 98.8% (93.9 ± 4.3%) for samples fortified with 2.0–50 ng ivermectin/mL. Coefficients of variation were 3.2–11.0%. The limit of detection was 1 ng/mL in 5.0 mL serum.
Comparison of Three Methods for Determining Aflatoxins in Melon Seeds
Authors: Diprossimo Vincent P , Malek Emil G
Published: February 2020

The suitability of 3 methods for determining aflatoxins in melon seeds was examined. The first 2 are the Contaminants Branch (CB) method and the Best Foods (BF) method, both official methods for determining aflatoxins in peanuts and peanut products. The third method, the modified CB method–Rapid Modification of the Cottonseed (CB-RCSMod) method, devised in this work, was derived by combining steps from the CB method and the Rapid Modification of the Cottonseed method. The CB method was superior to the other 2 methods for quantitation of aflatoxins. It gave better recoveries and cleaner extracts that exhibit less fluorescent interference for thin-layer chromatography (TLC) than the BF method. Also, its solvent efficiency was better than that of the CB-RCS-Mod method. With the CB method, recoveries from spiked samples were 85.0% for aflatoxin B1 and 90.0% for anatoxin B2. Recoveries of G1 aflatoxins were more variable, averaging 90.0% for aflatoxin d and 72.5% for aflatoxin G2. Total aflatoxin recovery was 86.5% for the CB method. At a low aflatoxin contamination level (8 μg B1/kg sample), aflatoxin B1 was detectable by the CB method but not by the BF method. Detection of aflatoxins in BF method sample extracts by TLC was not improved by the use of chloroform–acetone–water (88 + 12 + 1), benzene–ethanol–water, or ether–methanol–water (96 + 3 +1) in place of the standard chloroform–acetone (88 + 12) developer. Use of ether–methanol–water (96 + 3 + 1) for detecting aflatoxins by TLC in the CB method extracts increased interference compared with the standard chloroform–acetone (88 + 12) developer.
Comparison of Modified TECRA Visual Immunoassay with AOAC Method 989.14 and Reference Culture Methods 967.25–967.28 for Detection of Salmonella in Foods and Related Samples
Authors: Hughes Denise , Dailianis A , Ash M
Published: February 2020

A validation study was conducted to compare a new modified version of the TECRA Salmonella Visual Immunoassay (Mod. VIA) with the original immunoassay (AOAC Method 989.14) and the reference culture methods (967.25–967.28). The Mod. VIA was supplemented with polyclonal antibodies to Salmonella pullorum and S. galllnarum, and compared favorably with AOAC Method 989.14 in sensitivity, inclusivity, and exclusivity studies. The ability of the Mod. VIA to recover Salmonella from artificially contaminated samples was not significantly different from that of the reference method. It is recommended that the Mod. VIA be adopted as Official First Action.
Determination of Aflatoxin Bi in Pistachio Kernels and Shells
Authors: Scholten Jos M , Spanjer Martien C
Published: February 2020

A method was developed for accurate measurement of aflatoxin B1 in the edible portion of pistachio nuts. Twenty-nine samples of kernels with and without their shells were slurried with a Mega Ultra Turrax. A subsample of the homogenate was extracted with water–methanol, defatted with petroleum ether, purified with a silica solid-phase extraction column, and redissolved in methanol. After separation on an octadecy! column and postcolumn reaction with on-line electrochemically generated bromine, the aflatoxin Bi derivative was detected fluorometrically. The shells contained less than 1 % of the aflatoxin Bi found in the edible kernel, and they accounted for 41.7–46.8% of the weight of the whole pistachio. These observations indicate it is possible to analyze an entire sample, up to 25 kg, as a whole and still be able to judge whether it meets the legal tolerance limit of 5 μg aflatoxin B1/kg edible part, as set by the Dutch Food Act.