bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Shell Content in Palm Kernel Cake
Authors: Wai-Lin Siew
Published: February 2020

A method for determining shell in palm kernel cake (PKC) is described. This simple and rapid method requires little pretreatment compared with the method currently used in PKC trade, in which the sample undergoes defatting, acid and alkali digestion, and washing, before a chloroform-alcohol solution is used to separate the shells. In the proposed method, only defatting the sample is required. The shells are separated by the density difference between the shell and PKC in a potassium iodide solution. Recoveries of at least 93% were obtained, and the correlation coefficient between the actual shell content and the determined shell content was 0.999, with gradients of 0.97 and 0.98 for fine and coarse shell, respectively.
Rapid Liquid Chromatographic Determination of Fatty Acids as 2-Nitrophenylhydrazine Derivatives
Authors: Miwa Hiroshi , Yamamoto Magobei
Published: February 2020

Direct derivatization of saponified fats and oils with 2-nitrophenylhydrazine hydrochloride produced corresponding fatty acid hydrazides without timeconsuming sample cleanup and/or extraction steps. Hydrazides were injected directly into a liquid chromatograph. Improved isocratic separation was achieved within only 22 min for 29 saturated and mono- and polyunsaturated fatty acids (C8:0- C22:6), including cis-trans isomers and doublebond positional isomers. The technique has good quantitative accuracy while reducing analysis time, cost, and labor.
Occurrence of Pesticide Residues in Selected Agricultural Food Commodities Available in Canada
Authors: Neidert Eli , Saschenbrecker Peter W
Published: February 2020

During the 27-month period between January 1, 1992, and March 31,1994, Agriculture and AgriFood Canada analyzed 21 982 samples of fruit and vegetable commodities for pesticide residues. A multiresidue method capable of detecting over 200 analytes was used. In 5784 domestic samples a total of 676 residue findings were made. Of these, 32 (0.55%) were in violation of Canadian maximum residue limits (MRLs).In 16 198 imported products, 464 of 3193 residue findings exceeded MRLs, corresponding to a violation rate of 2.86%. One-half of domestic violations resulted from commodity–pes ticide combinations for which there are no Canadian approvals.
Determination of Bentazone in Waters by Solid-Phase Spectrofluorimetry
Authors: Vilchez José Luis , Torres-Bustos Diego , Blanc Rosario , Navalón Alberto
Published: February 2020

A sensitive method for determining trace amounts of bentazone was developed. The method is based on solid-phase spectrofluorimetry. Bentazone was fixed on a dextran-type anion-exchange gel, and the fluorescence of the gel, packed in a 1 mm thick quartz cell, was measured directly at an excitation wavelength of 338 nm and an emission wavelength of 436 nm by using a solid-phase attachment. The applicable concentration range was 2.0–120.0 μg/L, with a detection limit of 0.4 μg/L. The relative standard deviation at the 30.0 μg/L level was 1.2%. The method was used to determine bentazone in natural water samples. Recoveries were 96.0–102.5%.
Determination of Fat, Protein, and Lactose in Raw Milk by Fourier Transform Infrared Spectroscopy and by Analysis with a Conventional Filter-Based Milk Analyzer
Authors: Lefier Dominique , Grappin Remy , Pochet Sylvie
Published: February 2020

The accuracy of fat, crude protein (CP), true protein (TP), and lactose determinations of raw milk by Fourier transform infrared (FTIR) spectroscopy and by analysis with a conventional filter-based milk analyzer was assessed in 6 trials performed over a 10-month period. At each trial, 30 bulk milk samples collected from 15 European countries and 11 reconstituted milks made from raw milk components were analyzed. When calibrations were performed with reconstituted milks at each trial, accuracy standard deviations for fat, CP, TP, and lactose were, respectively, 0.050,0.048,0.035, and 0.076 g/100 g for the filter instrument and 0.047, 0.046,0.042, and 0.065 g/100 g for the FTIR instrument. When a single calibration was made instead of calibrations at each trial, accuracy standard deviations increased for the filter instrument to 0.130, 0.119,0.121, and 0.083 for fat, CP, TP, and lactose, respectively, and for the FTIR instrument to 0.082, 0.053,0.044, and 0.084 g/100 g. Because the FTIR instrument provides more spectral information related to milk composition than does the filter instrument, single-calibration FTIR analysis of milk samples collected in different seasons is more accurate. Using reconstituted milks, prepared such that there is no correlation between fat, CP, and lactose, provides a more robust calibration than using genuine bulk milk, especially when milks with unusual composition are analyzed.
Determination of Total Arsenic and Selenium in Soils and Plants by Atomic Absorption Spectrometry with Hydride Generation and Flow Injection Analysis Coupled Techniques
Authors: De Blas Oroncio Jiménez , Mateos N Rodriguez , Sanchez A Garcia
Published: February 2020

A procedure has been developed for determination of total arsenic and selenium in soils and plants by atomic absorption spectrometry with hydride generation associated with flow injection analysis (FIA-AAS-HG). Samples were wet-digested by using 2 systems: heating in a metal digestion block with controlled temperature and time and heating in a microwave oven. Total arsenic and selenium were reduced with NaBH4 and concentrated HCI, respectively. In both digestion systems used for the 2 matrix types, detection limits below 1 μg/L were found for both elements for an injection volume of 160 μL, with relative standard deviations of 3–6%. Recoveries by the method ranged from 93 to 105%; with the reference materials FD8 and MRG-1, the values obtained in all cases were consistent with the certified data. The FIA-AAS-HG procedure is highly suitable for determination of total arsenic and selenium in soils and plants, and because of the coupled system used, it is an improvement over other procedures in terms of sample treatment, sample consumption, and automation.
Levels of Organochlorine Pesticides in Mexican Butter
Authors: Waliszewski Stefan M , Pardío Violeta T , Waliszewski K N , Chantiri Jorge N , Infanzón Rosa M
Published: February 2020

Organochlorine pesticide residues were analyzed in 345 samples of butter purchased from Mexican supermarkets in 1994. Three national brands and one foreign brand were analyzed. Most samples contained residues of γ-HCH (91 %), HCB (90%), and p,p′-DDE (88%). Residues of α-HCH (63%), p,p′-DDT (42%), ß-HCH (38%), o,p′-DDT (17%), heptachlor epoxide (7%), and endosulfane sulfate (3%) were also detected. Mean values of pesticide residues determined were 0.093 mg/kg fat for total HCH and 0.056 mg/kg for total DDT. Mean values of organochlorine pesticide residues in Mexican butter were comparable with those in a foreign brand.
Thin-Layer Chromatographic Detection of Phosphorothionate and Phosphorothiolothionate Pesticides Using 4-Amino-N,N-Diethylaniline
Authors: Pasha Akmal , Vuayashankar Yadathora N , Karanth Nitturu G K
Published: February 2020

A thin-layer chromatographic method using a novel chromogenic reagent was developed to detect the phosphorothionate and phosphorothiolothionate groups of pesticides. On reaction with 4-am'mo-N,N-diethylaniline and subsequent exposure to bromine vapor, these compounds yield a deep magenta product. The chromogenic reagent is specific to these organophosphates and gives no response to phosphorothiolates and substituted phosphonates. The method is rapid and highly sensitive. The limit of detection is 0.05-0.5 μg.
Use of Urease-Bromothymol Blue-Agar Method for Large-Scale Testing of Urine on Grain and Seeds
Authors: Valdes Patricia A , Ziobro George C , Ferrera Robert S
Published: February 2020

The current AOAC method (963.28) for large-scale (50 g) testing of urine on grain is based on the reaction of sodium in urine with magnesium uranyl acetate. Detection of sodium suggests that urine is present and that a test for urea is appropriate. Urea is detected with urease-bromothymol blue-paper and is confirmed through its reaction with xanthydrol to form dixanthylurea crystals, which are detected microscopically. The initial nonspecific test for sodium can be influenced by the presence of salt or other sodium compounds. Furthermore, the magnesium uranyl acetate spray used in Method 963.28 potentially exposes the analyst to the aerosol of a volatile, toxic uranium compound. Excess reagents and analyzed test portions must be disposed of as radioactive waste. In addition, Method 963.28 requires several steps to determine the presence of urea. The alternative AOAC method (972.41) tests for the presence of urea from urine on individual seeds. Urea is enzymatically decomposed to ammonia and carbon dioxide by urease.Liberated ammonia shifts the pH, changing the color of the indicator in the agar from yellow to blue. This study adapts Method 972.41 to larger test samples. Up to 25 g grains and seeds are sprayed with urease test agar instead of being individually immersed in the urease test agar. The modified method was used to analyze urea on seeds and grains of 24 plants from 4 families. The method has a limit of detection of one seed contaminated with 1μg urea.
Determination and Survey of Deoxynivalenol in White Flour, Whole Wheat Flour, and Bran
Authors: Trucksess Mary W , Ready Duwayne E , Pender Marie K , Ligmond Cathy A , Wood Garnett E , Page Samuel W
Published: February 2020

A liquid chromatographic (LC) method for determining deoxynivalenol (DON) in white flour, whole wheat flour, and bran was developed. A 25 g test portion was extracted with acetonitrile-water (84 + 16), and the extract was filtered and applied to a column containing a combination of charcoal, Celite, and other adsorbents. The eluate was then chromatographed on a silica-based, reversedphase LC column by using a gradient of water and methanol. DON was measured at 220 nm. Average recoveries of DON from white flour, whole wheat flour, and bran spiked at 1 fig/g were 88,86, and 85%, respectively. The limit of determination of the method was <0.5 μg/g. A total of 562 wheat-based products from the 1993 crop year were collected by 21 U.S. Food and Drug Administration District Offices and analyzed by this method in Kansas City, Seattle, and New Orleans District Laboratories. The numbers of samples with DON contamination ≥1 μg/g from 163 bran, 272 white flour, 90 whole wheat flour, and 37 miscellaneous test samples were 20,28,14, and 2, respectively. About 52,50,40, and 27% of the same test samples were contaminated with DON at levels ≥0.1 μg/g.
Supercritical Fluid Extraction of Volatile N-Nitrosamines in Fried Bacon and Its Drippings: Method Comparison
Authors: Fiddler Walter , Pensabene John W
Published: February 2020

N-Nitrosopyrrolidine (NPYR) and N-nitrosodimethylamine (NDMA), known animal carcinogens, are consistently formed in bacon during frying. As a result, commercial bacon has been subject to regulatory monitoring and compliance for the past 20 years to ensure that N-nitrosamines do not exceed the 10 ppb violative level. Currently, time-consuming distillation-solvent extraction and solidphase extraction (SPE) methods are used for this purpose. With an emphasis on reducing solvent use, we investigated supercritical fluid extraction (SFE) using supercritical carbon dioxide (SC-CO2) for isolation of volatile nitrosamines common to fried bacon. Eighteen fried bacon samples were analyzed for NPYR and NDMA by SFE, SPE, mineral oil distillation (MOD), and low-temperature vacuum distillation (LTVD) methods, using the same gas chromatographic-chemiluminescence detection (thermal energy analyzer) conditions. The range of values for SFE was 0.7 to 20.2 ppb for NPYR and none detected (ND) to 2.4 ppb for NDMA. Analysis of variance of the NPYR data showed a significant difference (p < 0.05) between SFE and SPE results and significant differences between these and those obtained by MOD and LTVD. Overall, SFE was superior to the other methods with the highest recoveries, best repeatability, rapidity of analysis, and solvent-sparing characteristics. Similar results were obtained for SFE after comparison with distillation and SPE methods for determining the same nitrosamines in fried bacon drippings.
Determination of Methomyl in Insecticidal Formulations by Reversed-Phase Liquid Chromatography: Collaborative Study
Authors: Conaway James E ,   Collaborators:, Audino J B , Bane E , Carrigan S K , Glinsky R , King S W , Law M W , McDermott W H , Minyard J T , Schreiber M L , Sherwood G A , Skelly N E , Whaley D E , Winstead G R
Published: February 2020

A reversed-phase liquid chromatographic (LC) method for methomyl was studied. Twelve collaborators analyzed 3 solid and 4 liquid formulations on both a Zorbax octadecylsilane (ODS) column and a similar column of their choice. Methomyl and the internal standard were separated by using a mobile phase consisting of approximately 8% acetonitrile in water, which was monitored at 254 nm. The coefficient of variation on the Zorbax column ranged from 0.70 to 5.23%, while the range on the collaborators' house columns was 1.08 to 6.01%. Results with the Zorbax ODS column fell within the 5% 2-tail limits, and 10 of 11 collaborators' results fell within these limits on house columns. The LC method for determination of methomyl in insecticidal formulations has been adopted first action by AOAC INTERNATIONAL.
Determination of Total Free and Glucose-Conjugated 3-Phenoxybenzyl Alcohol Residues in Foods by Gas Chromatography with Electron Capture Detection
Authors: Mortimer Richard D , Shields J Brian
Published: February 2020

A method was developed to determine the combined amounts of residual, free 3-phenoxybenzyl alcohol (permethrin alcohol) and its acetone-extractable glucosides in representative fruits and vegetables after application of pyrethroid insecticides such as permethrin or cypermethrin. 3-Phenoxybenzyl glucoside was synthesized and used to spike food samples. Conditions were developed for extraction, enzymatic hydrolysis, derivatization with heptafluorobutyric anhydride, and cleanup prior to detection and quantitation by gas chromatography with electron capture detection. Limits of detection in various foods were ≤0.01 ppm. In addition, 2 sets of field trial samples that were sprayed with permethrin and collected at intervals were also analyzed. In general, the amounts of total permethrin alcohol in foods were small.
Liquid Chromatographic Determination of Ochratoxin A in Barley, Wheat Bran, and Rye by the AOAC/IUPAC/NMKL Method: NMKL Collaborative Study1
Authors: Larsson Kjell , Möller Tord ,   Collaborators:, Berg S , Berntsson I , Eklund E , Hald B , Jacobsson K-G , Langseth W , MacDonald S , Majerus P , Mann P , Rasmussen G , Wood G
Published: February 2020

In an inter laboratory study of the AOAC/lnternational Union of Pure and Applied Chemistry (IUPAC)/ Nordic Committee on Food Analysis (NMKL) liquid chromatographic method for ochratoxin A (OTA), 3 spiked samples each of wheat bran and rye and 3 naturally contaminated barley samples with expected OTA contents between 2 and 9 μg/kg were analyzed by 12 European laboratories. Mean recoveries ranged from 64 to 72%. Within-laboratory standard deviations were 21,17, and 12% for wheat bran, rye, and barley, respectively. Corresponding between-laboratory standard deviations were 23-28,20-28, and 18-31%. Horwitz ratio values ranged from 0.50 to 0.77. The method was accepted as an official NMKL method for determining OTA at ≥2 μg/kg in cereals and cereal products.
Spectrometric Determination of Chromium in FD&C Blue No. 1 by X-Ray Fluorescence
Authors: Hepp Nancy M
Published: February 2020

An X-ray fluorescence spectrometry (XRF) method was developed and validated for determination of chromium in FD&C Blue No. 1. Results of this analysis were compared with those obtained with an atomic absorption spectroscopy (AAS) method currently used by the U.S. Food and Drug Administration. Levels of Cr, as determined by the XRF and AAS methods, were comparable. The limit of quantitation for the XRF method is 4 μg Cr/g. The predicted 95% confidence interval at the specification level is 50 ± 5 μg/g.
Trace Determination of Zinc by Substoichiometric Isotope Dilution Analysis
Authors: Sandhya Devalla , Priya Sampath , Subramanian Mandakolathur S
Published: February 2020

A radiometric method based on substoichiometric isotope dilution analysis using 1,10-phenanthroline and a substoichiometric amount of eosin was developed for determining trace amounts of zinc. Evaluation of various metal ion interferences showed that as little as 0.2 μg Zn could be determined in an aqueous-phase volume of 60 mL The method has been successfully applied to the determination of Zn in city waste incineration ash, cadmium metal, Fourts-B tablets, Boro-plus ointment, and magnesium alloy samples.
Solid-Phase Extraction Cleanup for Determining Ascorbic Acid and Dehydroascorbic Acid by Titration with 2,6-Dichlorophenolindophenol
Authors: Verma Krishna K , Jain Archana , Sahasrabuddhey Bhushan , Gupta Kalpana , Mishra Sanjeev
Published: February 2020

Ascorbic acid is frequently determined by titration with 2,6-dichlorophenolindophenol. The determination is rapid, but the method is neither specific for ascorbic acid nor very sensitive. The coloring matter in the assay solution interferes with the visual endpoint, and iron(ll), copper(l), sulfite, and sulfhydryl substances such as cysteine and glutathione interfere with the color reaction. Sample cleanup by solid-phase extraction with C18 bonded silica was developed to remove the coloring matter. Extraction sorbent impregnated with 2,2′-bipyridyl, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and Jv-ethylmaleimide removes Fe(ll), Cu(l), and sulfhydryl compounds, respectively. The procedure was applied to highly colored multivitamin pharmaceuticals, soft drinks, and fruit and vegetable juices. In contrast to the results from the original method, which is not applicable to such samples, the results obtained by the method incorporating cleanup were accurate and selective for ascorbic acid. The sample cleanup also permitted determination of dehydroascorbic acid by reducing it to ascorbic acid with cysteine and titrating the ascorbic acid formed with indophenol. As little as 3 μg ascorbic acid was determined by the method incorporating cleanup.
Biosensors for Measuring Pesticide Residues in the Environment: Past, Present, and Future
Authors: Krämer Petra M
Published: February 2020

Inexpensive, fast, reliable, sensitive biosensors and automated devices are being developed for broad-spectrum analysis or specific analysis of single analytes. This paper discusses biosensor research in environmental analysis, focusing on pesticide analysis. Examples are presented from major research fields to serve as a starting point for information about trends and to encourage more research in this interdisciplinary field
Comparison of Automated and Traditional Minimum Inhibitory Concentration Procedures for Microbiological Cosmetic Preservatives
Authors: Lenczewski Melissa E , McGavin Sean T , Vandyke Karl
Published: February 2020

Minimum inhibitory concentration (MIC) is used to test resistance of microorganisms against antibiotics and to test cosmetic preservatives. This research expanded traditional MIC with automation and application of colorimetric endpoint MIC. All experiments included common cosmetic preservatives and microorganisms used in testing preservative efficacy. An autodilutor using three 96-well microliter plates processed 6 preservatives against 1 microorganism in 15 min. The unique tip design made it possible to accurately deliver viscous test materials that cannot be dispensed accurately with vacuum or fluid-filled systems. Tetrazolium violet, a redox indicator, provided a visual color change from clear to purple at the MIC. Optimum concentration of tetrazolium violet was 0.01 % with addition of 0.2% glucose to Mueller-Hinton broth for both gram-positive and gram-negative bacteria. The colorimetric endpoint was evident after 24 h from previously cryogenically stored organisms that were thawed before use and after 4 h for 18–24 h broth cultures subcultured from agar plates. The autodilutor accurately pipetted viscous cosmetic products such as hand lotion and shampoo, which cannot be pipetted with a traditional micropipetter.
Rapid and Selective Ultraviolet Spectrophotometric Assay of Aspirin in Complex Tablet Formulations
Authors: Sanyal Asis K , Dutta Ashok
Published: February 2020

A simple UV spectrophotometric technique was developed for rapid estimation of aspirin in complex tablet formulations. The method is based on measurement of the change in absorbance at 302 nm due to formation of salicylic acid during hydrolysis of aspirin in 0.09N NaOH. The change in absorbance follows a linear relationship with aspirin concentration in the range of 10–50 μg/mL. The method was applied to various complex tablet formulations. Recoveries of aspirin from these formulations, excipients, additives, and active ingredients confirmed the applicability of the method to complex aspirin formulations.
Relative Effectiveness of Selenite Cystine Broth, Tetrathionate Broth, and Rappaport-Vassiliadis Medium for Recovery of Salmonella spp. from Raw Flesh, Highly Contaminated Foods, and Poultry Feed: Collaborative Study
Authors: June Geraldine A , Sherrod Patricia S , Hammack Thomas S , Amaguaña R Miguel , Andrews Wallace H ,   Collaborators:, Arling V , Ayers S , Ayotte E , Cirigliano M , Clifford D C , Cook D , Coles C , Dabney A , Davis T , Diaz B , Driggs R M , Eliasberg S , Fain A , Fung D Y C , Hammers A , Hu E , Jirele K , Keating K J , Kogan S , Kone K , Kuyyakamont B , Luebbert K , McDonagh S , McNally S , Mettler D , Milas J , Miller C , Nelson T , Nguyen P , Pfundheller R , Phebus R K , Redding R , Richardson S , Richter E , Robinson J , Romer J , Roo D W , Smoot L , Snow K , Tate C , Tompkins L , Vanderbilt K , Varney G W , Wagner D , Wang J , Wchienroj K
Published: February 2020

A collaborative study was performed in 18 laboratories to validate use of Rappaport-Vassiliadis (RV) medium in the standard culture method for recovery of Salmonella spp. from raw, highly contaminated foods and poultry feed. RV medium made from its individual ingredients and incubated at 42�C was compared with selenite cystine (SC) broth incubated at 35�C and tetrathionate (TT) broth incubated at 35� and 43�C for effectiveness in recovery of Salmonella spp. Four artificially contaminated foods (oysters, frog legs, mushrooms, and shrimp) and poultry feed and one naturally contaminated food (chicken) were analyzed. The artificially contaminated foods were inoculated with single serovars of Salmonella at target levels of 0.04 colony-forming units (CFU)/g for the low level and 0.4 CFU/g for the high level. For analysis of 1125 test portions, RV medium (42�C) recovered Salmonellairom 409 test portions; TT (43�C), from 368 test portions; TT (35�C), from 310 test portions; and SC (35�C), from 334 test portions. Overall, RV medium was comparable with or better than other selective enrichments for recovery of Salmonella from the foods in this study, except mushrooms. From mushrooms, SC broth (35�C) recovered more positive test portions than did RV medium (42�C) and TT broth (43�C). The method for detection of Salmonella in raw, highly contaminated foods and
Determination of Organochlorine, Organophosphorus, and Triazine Pesticide Residues in Wine by Gas Chromatography with Electron Capture and Nitrogen–Phosphorus Detection
Authors: Garcia-Repetto Rosario , Garrtoo Isabel , Repetto Manuel
Published: February 2020

A multiresidue analytical method is described for determining 6 pesticides in wine: chlorpyrifos, dimethoate, quinalphos, simazine, tetradifon, and endosulfan. Wine (200 mL) is extracted with dichloromethane (50 mL, 3 times), and the evaporated extracts are purified by silica gel chromatography. Pesticide residues are eluted with n-hexane, n-hexane-benzene (1 + 1), benzene, benzene–acetone (1 + 1), and acetone. Residues are determined by gas chromatography with nitrogen–phosphorus and electron capture detection, using CPSH-5CB, Carbo wax-20M, and CPSH-19CB columns. Recoveries of pesticides added at 0.025 μg/L were 83–97%, with standard deviations of 0.01–0.05%. Detection limits were 0.13–8.9 ng/L, except for simazine (36.7 μg/L). Results are compared with those obtained with a solid-phase extraction (C18) purification and with different eluant series.
Determination of Methylene Blue in Channel Catfish {Ictalurus punctatus) Tissue by Liquid Chromatography with Visible Detection
Authors: Turnipseed Sherri B , Roybal José E , Plakas Steven M , Pfenning Allen P , Hurlbut Jeffrey A , Long Austin R
Published: February 2020

Methylene blue (MB) is a thiazine dye that, although not regulated for use with edible fish, may sometimes be used as a chemotherapeutic agent in the aquaculture industry. A liquid chromatographic (LC) method was developed for the determination of MB in fish muscle. MB was extracted from catfish tissue with an acetonitrile-acetate buffer solution containing hydroxylamine and toluene- sulfonic acid, partitioned into methylene chloride, and cleaned up on alumina and carboxylic acid solid-phase extraction cartridges. MB concentrations were determined by LC with visible detection at 660-665 nm. Recoveries of MB from catfish fortified at 10-50 ng/g were 75-90% (RSDs, 5-12%). Leu- comethylene blue also can be recovered from catfish tissue as the MB colored form at low levels with similar recoveries. Analysis of catfish exposed to MB in a bath treatment at 5 ppm MB for 1 h recovered 10-20 ppb of the drug in the muscle tissue. The low tissue concentration suggests poor absorption of this drug compared with other antifungal dyes that tend to concentrate and remain in fish tissue at high levels.
N-Nitrosodibenzylamine in Boneless Hams Processed in Elastic Rubber Nettings
Authors: Fiddler Walter , Pensabene John W , Gates Robert A , Custer Carl , Yoffe Aron , Phillipo Tom
Published: February 2020

Boneless hams processed in elastic rubber nettings contain high levels of nitrosamines in the outermost layer. The precursors of the nitrosamines are zinc dibutyl-or dibenzyldithiocarbamate used as a vulcanizing agent in the formulation of the rubber. The outermost layer from 59 commercial hams was analyzed for 11 volatile nitrosamines including N-nitrosodibutylamine (NDBA) and N-nitrosodibenzylamine (NDBzA). The principal nitrosamine, NDBzA, was detected in 32 (54%) ham samples at the 10-100 ppb range; it exceeded 100 ppb in 18 (30%) samples, with the highest at 512.2 ppb. No nitrosamine was detected in 7 of 59 ham samples. To determine the cause of the high NDBzA values, various types of unused nettings (from different manufacturers) accompanying the samples were analyzed for nitrosamines. No correlation was found between the NDBzA content of the hams and the nettings. The results suggest that the problem of nitrosamine formation in these products has not yet been resolved.
Determination of Total, Saturated, Unsaturated, and Monounsaturated Fats in Cereal Products by Acid Hydrolysis and Capillary Gas Chromatography: Collaborative Study
Authors: Ngeh-Ngwainbi Jerry , Lin James , Chandler Anthony ,   Collaborators:, Bannon C , Carr K , Condra C , Fagerle R , Fein R , Fusnacht J , Graff T , Hussein A , Kanno A , Kraft N , Kraus D , Marcuson D , Mitchell B , Oehrl L , Oles P , Patzer S , Sackett P , Salata S , Buick D , Sinclair A , Wo C , Scheelings P , Sudler M , Sullivan D , Williams A , Zygmunt L
Published: February 2020

Fifteen laboratories participated in a collaborative study to determine total, saturated, unsaturated, and monounsaturated fats in cereal products by gas chromatographic (GC) analysis of fatty acid methyl esters (FAMEs). Cereal products, representing a wide range of cereal grains and processes, were hydrolyxed in 8N HCI and extracted with ethyl and petroleum ethers. FAMEs were produced by the reaction of the mixed ether extracts with sodium hydroxide in methanol (NaOH/MeOH) and then with boron trifluoride reagent (14% BF3 in MeOH). They were quantitatively determined by capillary GC. Total fat was calculated as the sum of individual fatty acids expressed as triglyceride equivalents in accordance with nutrition labeling guidelines. Saturated, unsaturated, and monounsaturated fats were calculated as sums of individual fatty acids. The total fat contents of samples ranged from 0.56 to 12.64%. A split design was used to determine performance parameters of results obtained by 15 laboratories on 24 samples. Of the 24 samples, 7 were blind duplicates and 5 were independent materials. Statistical analysis for total fat yielded a relative standard deviation for repeatability (RSDr) range of 1.32 to 13.30% and a relative standard deviation for reproducibility (RSDr) range of 4.42 to 22.82%. The goal of this study was to determine total fat, saturated fat, unsaturated, and monounsaturated fat in cereal-based products by complete extraction, methylation, and quantitation of total fatty acids. The acid hydrolysis-capillary GC method for determining total, saturated, unsaturated, and monosaturated fats in cereal products has been adopted by AOAC INTERNATIONAL.
Determination of Dislodgeable Residues of N-4-Chlorobenzoyl-N’-Benzoyl-N’-tert-Butylhydrazine (RH-0345) from Grass by Liquid Chromatography
Authors: Skorczynskis Stephen S
Published: February 2020

A simple method for determining chemically and physically dislodgeable residues of N-4-chloroben-zoyl-N′-benzoyl- N′-tert-butylhydrazine (RH-0345) from grass is described. To determine chemical dis- lodgeability, a sample of fresh grass leaves is washed with deionized water containing a small amount of the wetting agent Aerosol OT-75. Quantitation of residues removed from the grass is based on the total surface area of grass analyzed. Physical dislodgeability is measured by sampling an area of turf for 1 min. Sampling is accomplished by a person wearing a dosimeter made from a common athletic sock. Grass-stained socks are extracted with 75% acetonitrile in deionized water, and the extracts are diluted with water. Quantitation of physically dislodgeable residues is based on the total RH-0345 residue adsorbed on the sock and is expressed as ng RH-0345/cm2 of sock in contact with the grass. For amounts of dislodgeable residues greater than the threshold value of 250 ng/cm2 for grass and 100 ng/cm2 for socks, extracts are analyzed directly by liquid chromatography (LC) using a C8 column and UV detection at 260 nm. For samples with significantly lower amounts of dislodgeable residues, diluted extracts are partitioned with methylene chloride. The methylene chloride containing the RH-0345 residues is evaporated just to dryness, and the residues are reconstituted in 30% acetonitrile in water and then analyzed by LC. The validated sensitivity of the method is 0.5 ng/cm2 for grass and 50 ng/cm2 for cotton socks. Grass was fortified at 0.5–10 000 ng/cm2. Average RH-0345 recovery from grass was 94 ± 10% standard deviation (SD). Apparent RH-0345 residues in control grass were 0.0558 ng/cm2. Socks were fortified at 50–40 000 ng/cm2. Average RH-0345 recovery from socks was 98 ± 7% SD. Apparent RH-0345 residues in control socks were 6.13 ng/cm2.
Liquid Chromatographic Determination of Glyphosate in Water-Soluble Granular Formulations: Collaborative Study
Authors: Morlier Lynn W , Tomkins David F ,   Collaborators:, Koppen B , Declercq B , Weller O , Gregoric A , Focht C , Roberts G , Harbin D , Schreuder R H , Hicks H , Verbist F , Wieland T , Bjorholm T , Manso L , Cohen S , Lee E , Zurcher T , Muller M D , Tomkins D F , Noble A , Schlesinger H D , Smallage B , Tarn K C , Kim Y-W , Sato T , Schultz D I , Parsons A , Galoux I M , Hussain M , Masollerx F M E
Published: February 2020

A liquid chromatographic (LC) method for the determination of glyphosate in various water-soluble granular formulations was tested by 28 laboratories. Samples were dissolved in mobile phase and injected directly into an LC system with a 25 cm SAX column and a mobile phase of 96% aqueous buffer solution, 0.0062M KH2PO4, and 4% methanol. Detection was by UV absorption at 195 nm. Manual or automated injections were made via fixed-volume loops. Calculations were based on peak area comparisons with external standards. The collaborative study analyzed 5 matched pairs of 4 water-soluble granular formulations, with one determination per sample. The study generated 138 matched pairs, which were analyzed by using the AOAC spreadsheet and Youden’s matched-pair calculations. Coefficients of variation for the 4 formulations ranged from 0.65 to 1.37%. The LC method for the determination of glyphosate in water-soluble granular formulations has been adopted first action by AOAC INTERNATIONAL.
Liquid Chromatographic Determination of Acriflavine and Proflavine Residues in Channel Catfish Muscle
Authors: Plakas Steven M , El Said Kathleen R , Jester Edward L E , Bencsath F Aladar , Hayton William L
Published: February 2020

A liquid chromatographic (LC) method was developed for determination of acriflavine (ACR) and proflavine (PRO) residues in channel catfish muscle. Residues were extracted with acidified methanol solution, and extracts were cleaned up with Ci& solid-phase extraction columns. Residue concentrations were determined on an LC cyano column, with spectrophotometric detection at 454 nm. Catfish muscle was individually fortified with ACR (purified from commercial product) and PRO at concentrations of 5,10,20, 40, and 80 ppb (5 replicates per level). Mean recoveries from fortified muscle at each level ranged from 86 to 95%, with relative standard deviations (RSDs) of 2.5 to 5.7%. The method was applied to incurred residues of ACR and PRO in muscle after waterborne exposure of channel catfish to commercial acriflavine (10 ppm total dye for 4 h). RSDs for incurred residues of ACR and PRO were in the same range as those for fortified muscle. Low residue concentrations (<1 % of exposure water concentration) suggested poor absorption of ACR and PRO in catfish.
VIDAS Enzyme-Linked Fluorescent Immunoassay for Detection of Salmonella in Foods: Collaborative Study
Authors: Curiale Michael S , Gangar Vidhya , Gravens Carol ,   Collaborators:, Agin J R , Bound A , Bowles L , Brockman R , Brusatti L , Bulawka C E , Cohen A , Deeks C , Eklund C A , Fukuoka J , Gangar V , Hammer C , Harris L , Hoffman C , Jost-Keating K , Keng J G , Kerdahi K , Krzyanowski W , Manley D , Miller C , Mondon D , Neufang K , Niroomand F , Plante R , Post L , Roman M , Rude D , Raghubeer E V , Ryder J , Smith C , Stoltzner L , Thomas L , Vanderbilt B , Wright T
Published: February 2020

The VIDAS SLM method for detection of Salmonella was compared with the Bacteriological Analytical Manual (BAM)/AOAC culture method in a collaborative study. Twenty laboratories participated in the evaluation. Each laboratory tested one or more of 6 test products: milk chocolate, nonfat dry milk, dried whole egg, soy flour, ground black pepper, and ground raw turkey. No significant differences (P< 0.05) were observed between the 2 methods. The 2 methods were in agreement for 99% of 1544 samples analyzed. Of the 20 samples out of agreement, 8 were VIDAS SLM positive and BAM/AOAC negative, and 12 were VIDAS SLM negative and BAM/AOAC positive. The VIDAS SLM method for detection of Salmonella in foods has been adopted first action by AOAC INTERNATIONAL.
High-Sensitivity Dry Rehydratable Film Method for Enumeration of Coliforms in Dairy Products: Collaborative Study
Authors: Curiale Michael S , Gangar Vidhya , D’onorio Armando , Gambrel-Lenarz Sonya , Mcallister J Sue ,   Collaborators:, Bailey B , Bednar A M , Bowen B , Brown D , Bulthaus M , Cash J , Cirigliano M , Cox M , D’onorio A , David O E , Fraser J , Frye K , Gangar V , Gambrel-Lenarz S , Hanlin J , Helbig T , Johnson J , Jost-Keating K , Kora L , Koeritzer R , Kozlowski S , Kraemer M , Lally S , Lambeth B , Lawlor K , Lewandowski V , Lopez S , McDonald S , Mclntyre S , Naq M , Pierson M , Reinhard J , Richter D , Saunders L , Simpson P , Smoot L , Tong M S , Warburton D , Williams H , Wilson-Perry A , Yuan J
Published: February 2020

A dry-film coliform count plate that is inoculated with 5 mL sample was compared with the Violet Red Bile Agar plate method in a collaborative study by 18 laboratories. Products analyzed were 2% milk, chocolate milk, cream, vanilla ice cream, cottage cheese, and cheese. Collaborators tested blind duplicate uninoculated samples and samples inoculated at low, medium, and high level. Significantly (P< 0.05) higher numbers of coliforms were recovered by the dry-film method from 2% milk samples at the 3 inoculum levels, the chocolate milk at the low- and high-inoculum levels, and the cream at the high-inoculum level. Significantly higher counts were obtained by the agar method for cottage cheese samples at the low-inoculum level. The repeatability standard deviation for the dry-film method was significantly higher for the high-inoculum level chocolate milk sample and the medium-inoculum level cottage cheese. The same statistic was significantly higher for the agar method at all 3 inoculum levels in the 2% milk and the medium-inoculum level cream. The high-sensitivity dry rehydratable film method for enumeration of coliforms in dairy products has been adopted first action by AOAC INTERNATIONAL.
Visual Immunoprecipitate Assay (VIP) for Detection of Enterohemorrhagic Escherichia coli (EHEC) 0157:H7 in Selected Foods: Collaborative Study
Authors: Feldsine Philip T , Albo-Nelson Maria T , Brunelle Sharon L , Forgey Robin L ,   Collaborators:, Al-Hasani S , Ball C , Beatty S , Blanchfield B , Bowen B , Bremer N , Brookman D , Brookman S , Brushaber M , Bryant J , Bryant D , Bryant R , Chlebowski E T , Copeland F , Culak D A , Dalley E , Destro C , Finkenbiner D , Frissora R , Fung D Y C , Garcia G R , Gray M R , Hagen C J , Harshavardhan T , Hart-Thakur R , Inami G , Johnson S , Kandakai L V , Lessard D , Lin S , Liu V , Matiuck S , McAteer L , Miller L , Moon B , Nasri H , Pack L , Pilot K , Price C , Pruett P , Ramirez C , Richter D , Schmieg J A , Schultz G , Sloan E M , Sprague D M , Tebay D , Tomer J , Tuncan E , Warburton D , Watson M , West D
Published: February 2020

Five foods representative of a variety of food products were analyzed by the Visual Immunoprecipitate Assay (VIP) and the Bacteriological Analytical Manual (BAM) culture method for the presence of Escherichia coli 0157: H7. A total of 21 laboratories representing state and federal government agencies, as well as private industry, in the United States and Canada participated. Food types were inoculated with strains of E. coli 0157:H7, with the exception of one lot of poultry, which was naturally contaminated. During this study, a total of 1377 samples and controls were analyzed and confirmed, of which 508 were positive and 867 were negative by both methods. Two samples were positive by BAM and negative by VIP. Because of the study design, it was not possible for the BAM method to produce false-negative or false-positive results. The VIP assay for detection of EHEC in selected foods has been adopted first action by AOAC INTERNATIONAL.
Determination of Total, Saturated, and Monounsaturated Fats In Foodstuffs by Hydrolytic Extraction and Gas Chromatographic Quantitation: Collaborative Study
Authors: House Stephen D ,   Collaborators:, Lawson M , Hammill T , Mazal R , Meyer K , Balch B , Ngeh-Ngwainbi J , Oles P , Bailey S , Bakowski R , Phillipo T , Phist M , Polywacz J , Hill S , Menke L , Wise B , Powell S , Johnson R , Martin D
Published: February 2020

Using gas chromatography (GC), 10 collaborating laboratories measured total, saturated, and monounsaturated fats in 8 blind duplicate pairs of foodstuffs. The method involves a hydrolysis/ether extraction of fat followed by quantitative GC analysis versus an internal standard. Calculations were designed to comply with federal regulations as specified in the Nutrition Labeling and Education Act of 1990. The range of fat contents was about 150%. Collaborators received and analyzed (in triplicate) a pre-collaborative sample of known fat content as a practice sample. After satisfactory results were obtained, participants received the 16-sample set. The repeatability standard deviations (RSDr) for total fat ranged from 2.04 to 10.6%; the reproducibility standard deviations (RSDr) for total fat ranged from 3.74 to 15.8%. The hydrolytic extrac- tion-GC method for determination of fat (total, saturated, and monounsaturated) in foodstuffs has been adopted first action by AOAC INTERNATIONAL.
Liquid Chromatographic Method for Determination of Vanillin and Ethyl Vanillin in Imitation Vanilla Extract (Modification of AOAC Official Method 990.25): Collaborative Study
Authors: Kahan Sidney , Krueger Dana A ,   Collaborators:, Berger R , Filandro A , Hageman L R , Korpinski T , Lin S , Lally N E , Parrish M , Schoen K L
Published: February 2020

A collaborative study of a method for analysis of vanillin and ethyl vanillin in fortified and imitation vanilla flavors was performed. The method, which is an extension of AOAC Official Method 990.25, Vanillin, Vanillic Acid, p-Hydroxybenzaldehyde, and p-Hydroxybenzoic Acid in Vanilla Extract, Liquid Chromatographic Method, involves reversed-phase high-pressure liquid chromatography (LC) of the sample on a Cβ column with a water-methanol-acetic acid (89 + 10 + 1) mobile phase and UV detection at 254 nm. The method yields good recoveries of vanillin at 484 and 723 mg/100 mL and of ethyl vanillin from 37 to 400 mg/100 mL. For vanillin, repeatability (r) values were 8 mg/100 mL at a level of 155 mg/100 mL, 12 mg/100 mLat a level of 484 mg/100 mL, and 31 mg/100 mL at a level of 723 mg/100 mL. Reproducibility (R) values were 20 mg/100 mL, 55 mg/100 mL, and 137 mg/100 mL over the same range. For ethyl vanillin, r values were 2.4 mg/100 mL at a level of 37 mg/100 mL, 3.2 mg/100 mL at a level of 74 mg/100 mL, and 8.6 mg/100 mL at a level of 180 mg/100 mL. R values were 6.4 mg/100 mL, 5.4 mg/100 mL, and 22.0 mg/100 mL over the same range. AOAC Official Method 990.25 has been modified to include determination of ethyl vanillin in vanilla extract and artificial vanilla flavor.
Determination of ß-Glucan in Barley and Oats by Streamlined Enzymatic Method: Summary of Collaborative Study
Authors: Mccleary Barry V , Mugford David C ,   Collaborators:, Camire M C , Gibson T S , Harrigan K , Janning M , Meuser F , Williams P
Published: February 2020

A collaborative study was conducted involving 8 laboratories (including the authors’ laboratories) to validate the streamlined enzymatic method for determination of ß-D-glucan in barley and oats. In the method, the flour sample is cooked to hydrate and gelatinize ß-glucan, which is subsequently hydrolyzed to soluble fragments with the lichenase enzyme. After volume and pH adjustments and filtration, the solution is treated with ß-glucosidase, which hydrolyzes ß-gluco-oligosaccharides to D-glucose. D-Glucose is measured with glucose oxidase-peroxidase reagent. Other portions of lichenase hydrolysate are treated directly with glucose oxidase-peroxidase reagent to measure free glucose in test sample. If levels of free glucose are high, the sample is extracted first with 80% ethanol. For all samples analyzed, the repeatability relative standard deviation (RSDr) values ranged from 3.1 to 12.3% and the reproducibility relative standard deviation (RSDR) values ranged from 6.6 to 12.3%. The streamlined enzymatic method for determination of ß-D-glucan in barley and oats has been adopted first action by AOAC INTERNATIONAL.
Gas Chromatographic Method for Putrescine and Cadaverine in Canned Tuna and Mahimahi and Fluorometric Method for Histamine (Minor Modification of AOAC Official Method 977.13): Collaborative Study
Authors: Rogers Patricia L , Staruszkiewicz Walter ,   Collaborators:, Adams A , Atienza B , Berg R J , Chin H , DesJardins C , Gilgan M , Hansen L B , Hummer W , Jahncke M , Jester E , Kennedy K , Krzynowek J , McLachlan D , Mowdy D , Newton R T , Personeau J C , Rorberg J A , Shum G , Thomas T S , Wagner R , Whitby C , Yuen G
Published: February 2020

A collaborative study was conducted to test a modification to the AOAC fluorometric method for histamine (AOAC® Official Method 977.13) that substitutes 75% methanol as the extracting solvent. All other steps remain unchanged. The extracts prepared with 75% methanol were also used to collaboratively test a gas chromatographic (GC) method for determination of putrescine and cadaverine in seafood. In the GC method, the extracted diamines are converted to fluorinated derivatives, the reaction mixtures are passed through solid-phase extraction columns, and the derivatives are quantitated by electron capture GC after separation on an OV-225 column. Fourteen laboratories using the GC method for putrescine and cadaverine and 16 laboratories using the fluorometric method for histamine analyzed 14 canned tuna and raw mahimahi (including blind duplicates and a spike) containing 0.2-2.6 ppm putrescine, 0.6-9.1 ppm cadaverine, and 0.6-154 ppm histamine. At the 5 ppm level, recoveries ranged from 71 to 102% for putrescine and 77 to 112% for cadaverine; the respective repeatability relative standard deviations (RSDr) were 5.2 and 15%, and the respective reproducibility relative standard deviations (RSDR) were 8.8 and 18%. At the 50 ppm level, histamine recoveries ranged from 84 to 125%, RSDr was 3.6%, and RSDR was 9.4%. The GC method for determination of putrescine in canned tuna and cadaverine in canned tuna and mahimahi has been adopted first action by AOAC INTERNATIONAL, and the AOAC Official Method 977.13, Histamine in Seafood, Fluorometric Method, has been modified
Study of Pesticide Synthesis Residual Products in Commercial Chlorpyrifos Formulations
Authors: Melgosa Elena Romero , Barrio Cecilia áSaenz , Asensio Jesús Sanz , Bernal Javier Galbán
Published: February 2020

A method to separate and identify manufacturing residual products (MRPs) in commercial formulations of chlorpyrifos is presented. The method is based on 3 stages: (1) qualitative study by capillary gas chromatography, (2) separation by liquid chromatography, and (3) identification by mass spectrometry and nuclear magnetic resonance spectroscopy. Using this methodology, the authors identified different MRPs in commercial chlorpyrifos: a phosphorochloridothioic acid O,O-diethyl ester chloride, TCP (3,5,6-trichloropyridin-2-ol), and sulfotep (tetraethyl dithionopyrophosphate). In addition, a compound that has not been described until now, was identified. Given the name “Romerales,” the compound has toxicity similar to or greater than that of chlorpyrifos.
Planar Chromatographic and Liquid Chromatographic Analysis of Thiamphenicol in Bovine and Human Plasma
Authors: Dreassi Elena , Corbini Gianfranco , Ginanneschi Vittoria , Corti Piero , Furlanetto Sandra
Published: February 2020

A planar chromatographic (PC) method was developed to determine thiamphenicol in human and bovine plasma with florphenicol as internal standard. The performance of the method was compared with that of a liquid chromatographic method. Recovery of extraction method developed for plasma was 81.51 ± 2.85%. Reproducibilities of the PC assay performed with various PC plates were also good.
Liquid Chromatographic Determination of Thalidomide in Tablets, Capsules, and Raw Materials
Authors: Reepmeyer John C , Cox Don C
Published: February 2020

A simple, isocratic liquid chromatographic method for assay of thalidomide in tablets, capsules, and raw materials was developed. The method uses a Nova-Pak octadecylsilane bonded-phase column (150 × 3.9 mm, 4 μm particle size), a mobile phase of acetonitrile-water (15 + 85), a flow rate of 1 mL/min, detection at 237 nm, and phenacetin as internal standard. Phosphoric acid was used in preparation of sample solutions to inhibit thalidomide hydrolysis. Assays ranged from 99.3 to 100.4% in raw materials from 4 manufacturers, from 79.7 to 104.8% in tablets from 7 manufacturers, and from 75.3 to 102.6% in capsules from 4 manufacturers. Assay method precisions for triplicate analyses on 5 days were 0.30% for tablets, 0.22% for capsules, and 0.22% for raw materials. Recovery from simulated tablet formulations was 100%. The method has been used to analyze individual tablets and capsules for determination of content uniformity.