bluuebunny/crossref_metadata_2025 huggingface dataset:
Freeze-Dried Mixed Cultures as Samples for Proficiency Tests and Collaborative Studies in Food Microbiology
Authors: Peterz Mats , Norberg Per
Published: February 2020

A method is presented for preparing samples of freeze-dried mixtures of microorganisms for proficiency tests and collaborative studies. The samples may include most microorganisms that are found in routine analysis in food laboratories. Transport of samples during 48 h did not decrease the number of microorganisms, nor was the variability among samples significantly affected by transport. The standard deviation of counts after 5 weeks of storage varied from 0.04 (Staphylococcus aureus) to 0.17 (Clostridium perfringens) log unit. Storage of samples for 10 weeks decreased the number of viable organisms by 0.02-0.43 log unit. Variability among samples increased for Providencia alcalifaciens and Bacillus cereus after 10 weeks of storage. No significant increase was found for the other organisms.
Determination of Lactose in Milk: Comparison of Methods
Authors: Essig Anita M , Kleyn Dick H
Published: February 2020

A new enzymatic method based on the spectrophotometric measurement of reduced NAD+ (β-nicotinamide-adenine dinucleotide) at 340 nm has been evaluated by comparing it with the AOAC copper reduction method. Ten samples of milk containing various levels of lactose were analyzed in duplicate by the enzymatic method, and 5 samples were analyzed by the copper reduction method. Statistical analysis using a factorial design revealed no statistical significance between results obtained by the 2 methods; recoveries were comparable, 97% or greater for all except one sample. There was no relationship between amount of lactose added and percent recovered.
Evaluation of Apple Juice Authenticity by Organic Acid Analysis
Authors: Evans Randall H , Soestbergen Anton W Van , Ristow Karen A
Published: February 2020

An organic acid profile provides valuable information regarding authenticity of apple juice. The presence of D-malic acid is a clear indication of adulteration because this isomer does not occur naturally. Fumaric and citric acid levels above trace amounts are also inconsistent with pure apple juice; therefore, measurement of these organic acids may also be used as an authenticity check. Citric acid, total malic acid, and fumaric acid were determined in a single scan by liquid chromatography (LC) for 30 known pure apple juice samples. The L-isomer of malic acid was measured by an enzyme-specific method, and the D-isomer was calculated as the difference between total malic acid and L-malic acid.
Pesticide, Heavy Metal, and Other Chemical Residues in Infant and Toddler Total Diet Samples. (III). August 1976–September 1977
Authors: Johnson Roger D , Manske Dennis D , New Dallas H , Podrebarac David S
Published: February 2020

The Total Diet Study has been conducted by the Food and Drug Administration, U.S. Department of Health and Human Services, since 1964 to monitor the diet of adults, and more recently the infant and toddler diet, for residues of pesticides and other chemicals. This report presents the residues found in 12 infant and toddler market baskets, i.e., items comprising the average 2-week diet of infants and toddlers, collected in 12 major cities in 4 geographical areas from August 1976 through September 1977. The analyses for each market basket were performed on composites of each of 11 food classes, and the results are presented in a variety of formats. In addition to chemical residues, the market baskets were also analyzed for 6 heavy metals: arsenic, lead, selenium, zinc, cadmium, and mercury. Results of recovery studies conducted with residue compounds of various types are also included in this report. The results for the adult market baskets for the same period are published as a separate report.
Influence of Phosphorus and Calcium on Flame Atomic Absorption Spectrophotometric Determination of Lead in Canned Fish Products
Authors: Serra Teresa M , Serrano J F Vale
Published: February 2020

Lead was determined in the presence of whole multiples of the P/Ca ratio found in Portuguese canned fish by flame atomic absorption spectrophotometry with and without using an ashing aid. Under our experimental conditions, use of the ashing aid eliminates P and Ca interference. Results with real samples, spiked with 1, 2,3, and 4 ppm lead, are presented and statistically treated.
Rapid Column Method for Determination of N-Nitrosodimethylamine in Malt
Authors: Havery Donald C , Perfetti Gracia A , Thomas Fazio
Published: February 2020

A rapid column elution method has been developed for the determination of N-nilrosodimethylamine (NDMA) in malt. The average recovery of NDMA added to malt at the 10 ppb level was 87%. When a single malt sample was analyzed 10 times, the NDMA found averaged 8.1 ppb with a coefficient of variation of 3.93%. In a study of 15 malt samples, data obtained by the column elution method were in good agreement with those from a vacuum distillation method.
Nuclear Magnetic Resonance Spectroscopic Determination of Dicyclomine Hydrochloride in Tablet, Capsule, and Injection Dosage Forms
Authors: Hanna George M
Published: February 2020

A rapid and specific nuclear magnetic resonance (NMR) spectroscopic method was developed for determining dicyclomine hydrochloride in tablet, capsule, and injection dosage forms. The method consists of an extraction step with chloroform, evaporation of the solvent, addition of maleic acid as an internal standard, dissolution of the mixture in deuterated chloroform-deuterated acetone (40 + 60), NMR spectral determination, and integration of the peaks of interest. The concentration of dicyclomine hydrochloride in the dosage form was calculated from the integral values for the peaks of the test compound and the internal standard. The average recovery value ±the standard deviation (n = 5) of dicyclomine hydrochloride added to synthetic samples was 99.7 ± 0.9% (coefficient of variation 0.9%). The assay values for various commercial tablets, capsules, and injectables analyzed by using the proposed method differed in all cases by <1% from those obtained by using the USP XX titrimetric method. There was no interference from stearate, an excipient found in tablets and capsules, or from chloral hydrate, a preservative found in injectables.
Liquid Chromatographic Determination of Benomyl in Wettable Powders
Authors: Stringham Rodger W , Teubert Wyatt E
Published: February 2020

Pesticide formulations containing benomyl are extracted with acetonitrile containing 3% n-butyl isocyanate (BIC) and chromatographed on a reverse phase C-18 column. The equilibrium of benomyl degradation to methyl 2-benzimidazoIe carbamate (MBC) and BIC is driven toward benomyl. Thus, the method offers quantitation of benomyl in its intact form, using a mobile phase of acetonitrile-2% acetic acid (80 + 20) and detection at 290 nm. This assay was evaluated for linearity, precision, recovery, stability, and matrix effects. Linearity checks of standard solutions and spiked samples yielded coefficients of determination, r2, of 0.9996 and 0.9998, respectively. Quadruplicate analysis of 5 benomyl formulations gave an average relative standard deviation of 1.95%. A multiple standard addition plot revealed the absence of matrix effects. Mean recovery of standard from the sample pool was 95% with a standard deviation of 3.5%. Samples chromatographed 2 weeks after extraction indicated excellent analyte stability.
Effect of Solvent Composition on Aflatoxin Fluorescence
Authors: Chang-Yen Ivan , Stoute Valerie A , Felmine Jane B
Published: February 2020

The influence of the chloroform-methanol solvent system on the fluorescence of aflatoxins Bi, B2, Gj, and G2 was investigated. Fluorescence intensity is markedly affected by solvent composition. The formation of excited state dimers and ionization are proposed to explain the effects observed.
Rapid Liquid Chromatographic Determination of Clopidol in Chicken Muscles
Authors: Mtema Canutte A , Nakazawa Hiroyuki , Takabatake Eigo
Published: February 2020

A simple, rapid, and sensitive liquid chromatographic method is described for the quantitative determination of trace amounts of clopidol (3,5- dichloro-2,6-dimethyl-4-pyridinol) in chicken muscles. Clopidol was extracted from tissues with acetonitrile and the extract was cleaned up on an alumina column and separated on an anion exchange column, using 0.5% acetic acid in methanol as eluant. The solvent in the eluate was evaporated and the residue was dissolved in methanol containing benzamide as internal standard. Clopidol was separated on a Zorbax ODS column (4.6 × 250 mm) by using acetonitrile–0.05M phosphate buffer, pH 7.0 (15 + 85 v/v%), and detected at 270 nm with 0.005 AUFS. Recoveries of clopidol added to chicken tissues at levels of 0.02, 0.05, and 0.1 μg/g were 94.8, 94.8, and 97.0%, respectively. This method is applicable to levels as low as 0.01 ppm clopidol in chicken muscle.
Liquid Chromatographic Determination of Acetaminophen in Multicomponent Analgesic Tablets
Authors: Krieger David J
Published: February 2020

A simple, rapid LC method is presented for the separation and determination of acetaminophen in analgesic preparations containing up to 6 additional active components. The method uses a C18 reverse phase column, methanol–0.75% acetic acid (1 + 3) mobile phase, and photometric detection in the ultraviolet region. Acetaminophen was effectively separated from chlorpheniramine maleate, phenylephrine hydrochloride, caffeine, salicylamide, aspirin, and phenacetin, as well as from salicylic acid, a degradation product of aspirin. Typical chromatograms of the separation of acetaminophen from the above compounds in synthetic mixture and in commercial multicomponent analgesic preparations are presented, along with reproducibility and recovery data.
Gas Chromatographic Determination of Fluazifop-butyl in Formulations: Collaborative Study
Authors: Bland Peter D ,   Collaborators:, Chenery L , Ellis N , Firestone L , Himley R , Hindle R , Hodgins E , Jung P , Jurgens D , King W , Owen M , Parker R , Sasser S , Winstead G , Wood G
Published: February 2020

A method is described for the determination of butyl 2-(4-(5-trifluoromethyl- 2-pyridinyloxy)phenoxy) propanoate in technical and formulated material by gas chromatography (GC). Samples of technical or formulated material are dissolved in methylene chloride containing dibenzyl succinate as internal standard. The solution is injected into a gas chromatograph fitted with a flame ionization detector and a 6 ft × 2 mm glass column. The column is packed with 3% OV-17 on 100–120 mesh Chromosorb WHP and is maintained at 230°C. Peak areas obtained at the retention times of the internal standard and the active ingredient are measured with an integrator. The quantity of fluazifop-butyl is determined by comparing the internal standard and active ingredient peak areas with the peak areas obtained from a calibration solution containing known amounts of internal standard and pure active ingredient. Four samples were chosen for collaboration: technical fluazifop-butyl, a 4 lb/US gal. emulsifiable concentrate, a 560 g/L oil concentrate, and a 5% granular. Fourteen collaborators carried out replicate determinations on each sample. Coefficients of variation between laboratories were 0.80 for the technical, 0.88 for the emulsifiable concentrate, 1.03 for the oil concentrate, and 2.04 for the granular. Parallel peak height determinations showed substantially higher coefficients of variation for all except the granular sample. The method has been adopted official first action.
Dry Column-Thermal Energy Analyzer Method for Determining N-Nitrosopyrrolidine in Fried Bacon: Collaborative Study
Authors: Fiddler Walter , Pensabene John W , Gates Robert A , Phillips John G ,   Collaborators:, Benson M J , Galeener C , Goldstein M M , Greenfield E , Havery D , Meyer K , Phillippo T , Seaman S , Sen N P , Webb C , White G
Published: February 2020

A dry column method for isolating N-nitrosopyrrolidine (NPYR) from fried, cure-pumped bacon and detection by gas chromatography-thermal energy analyzer (TEA) was studied collaboratively. Testing the results obtained from 11 collaborators for homogeneous variances among samples resulted in splitting the nonzero samples into 2 groups of sample levels, each with similar variances. Outlying results were identified by AOAC-recommended procedures, and laboratories having outliers within a group were excluded. Results from the 9 collaborators remaining in the low group yielded coefficients of variation (CV) of 6.00% and 7.47% for repeatability and reproducibility, respectively, and the 8 collaborators remaining in the high group yielded CV values of 5.64% and 13.72%, respectively. An 85.2% overall average recovery of the N-nitrosoazetidine internal standard was obtained with an average laboratory CV of 10.5%. The method has been adopted official first action as an alternative to the mineral oil distillation-TEA screening procedure.
Liquid Chromatographic Determination of Chlortetracycline in Premixes
Authors: Howell Harry R , Rhodig Lori L , Sigler Alan D
Published: February 2020

A liquid chromatographic method for determination of chlortetracycline in premixes has been developed and compared with the AOAC cylinder plate method (42.211 (1980)). Chlortetracycline is extracted with an acid–acetone solution, clarified, and chromatographed on a Vydac 201TP reverse phase column with UV detection at 280 nm. The mobile phase consists of water–dimethylformamide (88 + 12, v/v) containing 0.001M disodium EDTA, 0.05M citric acid, 0.013M sodium citrate, and 0.1M potassium nitrate. Results were linear over a broad concentration range and free from interferences from compounds normally found in premixes. Samples of chlortetracycline premixes were assayed by both this method and the AOAC method with excellent correlation between the 2 methods.
Reverse Phase Liquid Chromatographic Determination and Confirmation of Aflatoxin M1 in Cheese
Authors: Hisada Kazuo , Terada Hisaya , Yamamoto Katsuhiko , Tsubouchi Haruo , Sakabe Yoshio
Published: February 2020

A systematic method is proposed for determination and confirmation of aflatoxin M1 in cheese by liquid chromatography (LC). A sample of cheese is extracted with chloroform, cleaned up on 2 silica gel columns followed by a Sep-Pak C18 cartridge, and chromatographed on a 5 μm octadecyl silica column with fluorometric detection. The sample extract or standard is treated with n-hexane–trifluoroacetic acid (TFA) (4 + 1) for 30 min at 40°C. Analysis by LC with TFA-treatment of the extract provides quantitative data. Multiple assays of 5 samples of Gouda cheese spiked with aflatoxin M1 at levels of 0.5, 0.1, and 0.05 ) ng/g showed average recoveries of 93.2, 91.6, and 92.4%, with coefficients of variation of 2.63, 3.97, and 4.52%, respectively. Assay of 5 naturally contaminated cheeses resulted in 0.051–0.448 ng/g of aflatoxin M1. Limit of quantitation is about 0.01 ng/g. The identity of aflatoxin M1 is confirmed by treating aflatoxin M1 or the M2a. derivative with TFA-methanol (or ethanol) (3 + 1). The TFA-methanol reaction products of M2a could be detected quantitatively.
Sensitivity of Cultured Human and Mouse Fibroblasts to Trichothecenes
Authors: Abbas Hamed K , Shier W Thomas , Mirocha Chester J
Published: February 2020

Cultured human diploid fibroblasts and a cloned permanent line of Swiss mouse fibroblasts (3T3) have been adapted to a biological assay of trichothecenes and other toxic fungal metabolites both in purified form and as crude extracts. The assays are carried out in multi-well tissue culture trays with serial dilutions of toxins in 200 μL volumes of medium. Cells are cultured with the toxins for 3–4 days, fixed, and stained, providing a permanent record of results. The sensitivity of the assay ranges from 0.1 ng/mL (20 pg/assay) for T-2 toxin on mouse fibroblasts to no detectable toxicity at 5 μg/mL for cis-zearalenone and verrucarol. Human skin fibroblasts exhibit patterns of relative sensitivities similar to that observed with mouse fibroblasts, but the absolute sensitivities are much greater with mouse fibroblasts because they can be cultured at much lower cell densities.
Simultaneous Thin Layer Chromatographic Determination of Aflatoxin B1 and Ochratoxin A in Black Olives
Authors: Le Tutour Bernard , Tantaoui-Elaraki Abdelrhafour , Aboussalim Abdelhadi
Published: February 2020

A screening method has been developed for simultaneous determination of aflatoxin B1 and ochratoxin A in black olives. The technique includes extraction of both mycotoxins with aqueous methanol, cleanup using lead acetate, defatting with hexane, partitioning in chloroform, and thin layer chromatography. Detection limits are 5–7 μg aflatoxin B1 and 20 μg ochratoxin A/kg.
Specific Determination of α-Tocopherol in Food and Feed by Fluorometry. Part 1. Manual Method
Authors: Bourgeois Claude E , Pages Philippe S , Czornomaz Anne M , Albrecht Michel J , Cronenberger Lucien A , George Philippe R
Published: February 2020

The proposed fluorometric method for determining α-tocopherol is highly specific and sensitive, yet requires low-cost equipment available in any laboratory. It is robust and fairly fast (4 determinations in 100 min, sample preparation not included). It has been tested in parallel with a conventional thin layer chromatographic method on foods and feeds. The only necessary cleanup is the usual saponification. The unsaponifiable fraction can be extracted with ethyl ether or, preferably, with Extrelut columns. Isooctane is used as a carrier solvent. Reagents and their solvents are added to the isooctane solution before each successive reaction and are then eliminated by partition with water. The α-tocopherol (α-T) derivative always remains in isooctane. The first step is nitrosation and elimination of tocopherols and tocotrienols other than α-isomers. α-T is then oxidized to α-tocored (α-TR) with a mixture of sulfuric acid, ferric chloride, and iodine bromide. α-TR is then condensed to a new reagent: 4,5-dimethyl-o-phenylenediamine. The phenazine formed is strongly fluorescent. Iodine and bromine add to the double bonds of α-tocotrienol present and quench the fluorescence of its phenazine. A procedure for blank assays specifically inhibits the conversion of α-T to α-TR.
Convection Oven Determination of Loss of Mass on Drying of Quick Frozen French Fried Potatoes: Collaborative Study
Authors: Biltcliffe David O , Judd Hillary J , Wood Roger ,   Collaborators:, Bushnell A C , Crudington R , Evans R A , Fawcett R , Grange C N , Griffiths W , Hall P S , Harrison A J , Kidman S L , Meadows G , Reynolds S , Rymer T E , Shelton J H
Published: February 2020

A collaborative study was carried out on one of the methods submitted to the Joint Economic Commission for Europe (ECE)/Codex Alimentarius Commission Group of Experts on the Standardization of Quick Frozen Foods for the determination of moisture in quick frozen french (fried potatoes. The method was based on the determination of loss of mass of the sample on drying in a convection oven 16 h at 103±2°C. Two samples of uncooked quick frozen french fried potatoes and 2 samples of oven quick frozen french fried potatoes were analyzed by 14 and 13 laboratories, respectively. The method is simple and was found to be analytically satisfactory with repeatability and reproducibility values of 0.21 and 2.00 g/100 g french fried potatoes, and 0.29 and 3.00 g/100 g oven french fried potatoes, respectively. The method was adopted by the Group of Experts in preference to other proposed procedures for this determination. The method has been adopted official first action by AOAC.
Enzymatic-Ultraviolet Method for Measuring Lactose in Milk: Collaborative Study
Authors: Biltcliffe David O , Kleyn Dick H , Trout J Richard ,   Collaborators:, Azzara D , Bissonette J , Bradley R , Brown R , Chamberlin W , Cheryan M , Dimick R , Duthie A , Fox J , Sherbon J , Somkuti G , Zimmerman A
Published: February 2020

Collaborators in 8 dairy and food industry laboratories performed one lactose determination on each of 8 unknown samples of milk, lowfat milk, or skim milk, as 3 pairs of blind duplicates. Two known samples were provided to gain experience prior to analysis of the unknown samples. All of the above samples were also analyzed for lactose content by the official AOAC gravimetric method (16.507) by a commercial laboratory. From the overall mean of results on all samples, determinations by the enzymatic method averaged 0.49% lower than by the AOAC method. This difference was significant by the t-test (P = 0.05), which indicated a lack of agreement between the compared methods in determining lactose content. Standard deviations were similar for the 3 sets of blind duplicates which ranged between 3.67 and 4.55% lactose content. F-values revealed that variations between means obtained by laboratories differed significantly as compared with variations within laboratory means. The method has been adopted official first action.
Simplified Method for Liquid Chromatographic Determination of Carbofuran in Soils
Authors: Lauren Denis R
Published: February 2020

A simple, direct method is described for determining carbofuran (CF), 2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate, in soils. Methanol extraction is followed by hexane–methanol–water (2 + 4 + 1) partition and liquid chromatographic analysis of the aqueous layer with UV detection at 280 nm. The method specifies dilution of the partitioned extract with water to methanol–water (20 + 80), and injection of 1000 μL sample volumes. This technique allowed a 10-fold increase in sensitivity over direct injection from the partition step. Recovery of CF by the method is about 90%, and less than 0.4 μg CF/ g soil can be detected at a medium detector sensitivity of 0.04 AUFS.
Liquid Chromatographic Analysis System for Cyclopiazonic Acid in Peanuts
Authors: Lansden John A
Published: February 2020

A liquid chromatographic procedure has been developed for analysis of cyclopiazonic acid in peanuts. The chromatographic system specifies a C18 or C8 column loaded with 4-dodecyldiethylenetriamine and an aqueous mobile phase containing 4-dodecyldiethylenetriamine, zinc acetate, ammonium acetate, 2-propanol, and acetonitrile. Cyclopiazonic acid was extracted from peanuts with methanol-chloroform (20 + 80), partitioned into aqueous sodium bicarbonate, acidified, and back-extracted into dichloromethane. The limit of detection (280 nm UV) was approximately 4 ng and detector response was linear to at least 1 μg pure cyclopiazonic acid. The recovery of cyclopiazonic acid from peanuts spiked at 68.9, 210, and 955 μ/kg was 85.9% (12.86% CV), 72.9% (6.43% CV), and 81.4% (0.40% CV), respectively. Calculation of the chromatographic peak parameters based on the exponentially modified Gaussian model indicated that the C18 column produced less peak skewing than did the C8 column.
Short Liquid Chromatographic Method for Determination of Zearalenone and alpha-Zearalenol
Authors: Chang Henry L , Devries Jonathan W
Published: February 2020

A rapid method has been developed for the determination of zearalenone and alpha-zearalenol, using liquid-liquid partition for sample extract cleanup followed by liquid chromatography (LC) with fluorescence detection. The same extract can also be used for determination of aflatoxin by LC. Relative standard deviations for the method based on duplicate analyses are 4.18% for artificially contaminated samples and 13.92% for naturally contaminated samples. The method was compared with the AOAC method of extraction and column chromatography extract cleanup, using the same LC conditions for quantitation for both methods. Results showed a correlation coefficient of 0.990 with a mean zearalenone content by this method of 987.8 ppb, and 732.6 ppb by the official AOAC method. The detection limit of this method is 2.2 ppb for zearalenone and 1.5 ppb for alpha-zearalenol.
Recovery of Salmonella Species from Nonfat Dry Milk Rehydrated Under Rapid and Reduced Pre-enrichment Conditions: Collaborative Study
Authors: Poelma Paul L , Andrews Wallace H , Wilson Clyde R ,   Collaborators:, Bennett B , Elliot P H , Estela L A , Flowers R , Jogan M J , Lancette G A , Liddle K , Mastrorocco D A , McDonald R L , Moran A , Morrison D L , Noah C W , Okrend A , Roberts B , Romick T , Ruby R M , Sherman G , Singleton E R , Smith T , Sveum W H , Wagner C A , Wagner D E , Zipkes M R
Published: February 2020

A collaborative study was conducted to compare the relative efficiency of the AOAC rapid rehydration method with the reduced rehydration soak method for the recovery of Salmonella species from nonfat dry milk (NFDM). In the AOAC method, a 25 g sample of NFDM is rapidly rehydrated at a 1:9 sample/water ratio and mixed by swirling. After 60 min, the flask contents are adjusted to a pH of 6.8, and 0.45 mL of 1% aqueous brilliant green dye solution is added. The flasks are then incubated at 35°C. In the soak method, a 25 g sample of NFDM is gently added to the sterile brilliant green (BG) water at a 1:9 sample/ BG water ratio and allowed to soak undisturbed for 60 min at room temperature before incubation. Twelve collaborators analyzed 3 shipments of samples with the following results for the AOAC and soak methods: shipment 1—31 and 46 positive samples, respectively, with a 48% increase in detection by the soak method; shipment 3-45 and 66 positive samples, respectively, with a 47% increase in detection by the soak method; shipment 2—no significant difference in recovery of Salmonella species by the 2 methods. It is recommended that the official final action method for the detection of Salmonella species, 46.054- 46.067, be revised to use the soak method for the analysis of nonfat dry milk.
Enumeration of Total Coliforms, Fecal Coliforms, and Escherichia coli in Foods by Hydrophobic Grid Membrane Filter: Collaborative Study
Authors: Entis Phyllis ,   Collaborators:, Bennett B , Brodsky M H , Burgener D M , Carlson V L , Carson M , Catherwood K , Ciebin B S , Cox N A , Dahiya R S , Daley H , Devenish J , Erickson J , Fettig P , Foster R , Gorski J , Hall P A , Hunt S D , Jagow J , Jenkins P , Jordan P R , Krieger F , Kwan P , Lanier J M , Liliard H S , Martin A , Milling M E , Nakanishi H , Nath E , Oggle J , Okrend A , Pongchairerks V , Posey D , Rodriguez J , Rose B E , Sayfie J , Taylor C , Teramoto T , Vandellen E
Published: February 2020

A collaborative study was conducted in 18 laboratories to assess the performance of the hydrophobic grid membrane filter method against that of the AOAC official first action method 46.013-46.016 for enumerating total and fecal coliforms and Escherichia coli. The study was carried out on frozen breaded fish, raw comminuted poultry, unroasted walnut pieces, ground black pepper, and cheddar cheese. The hydrophobic grid membrane filter method recovered significantly larger numbers of target bacteria in 7 of the food/analysis combinations: fecal coliforms in fish; E. coli in poultry; fecal coliforms and E. coli in walnuts; and total coliforms, fecal coliforms and E. coli in black pepper. Random error (Sr2) associated with the hydrophobic grid membrane filter method was significantly lower than that of the reference method in over 30% of the paired sample series. The hydrophobic grid membrane filter method for total coliform, fecal coliform, and E. coli enumeration in foods has been adopted official first action.
Gas Chromatographic Determination of Fenvalerate Insecticide Residues in Processed Tomato Products and By-Products
Authors: Spittler Terry D , Argauer Robert J , Lisk Donald J , Mumma Ralph O , Winnett George , Ferro David N ,   Collaborators:, Bogus E , Greco E , Gutenmann W , Miles E , Simmons K , Walton J , Zimmerman L
Published: February 2020

The results of a 5-laboratory collaborative determination of residues of the synthetic pyrethroid insecticide fenvalerate in tomato products are presented. Tomatoes from plants treated in the field at 2-4 day intervals (13 foliar applications) were processed into chopped fresh tomatoes, canned quarters, juice, paste, and the by-product skins plus seeds. Gas chromatographic analysis of the commodities for fenvalerate showed the fresh produce to contain 0.26 ppm, and the skins plus seeds contained 1.9 ppm. Residues were barely detectable in canned peeled quarters and juice, but averaged 0.12 ppm for paste, the concentration product of juice. High residues were associated with the skin content of the product. Five laboratories using modifications of the same analytical technique obtained good collaborative agreement.
Identification and Semiquantitation of Monensin Sodium in Liver Tissue
Authors: Martinez Elizabeth E , Shimoda Wilbert
Published: February 2020

A bioautographic technique for the determination of monensin sodium in animal feed has been applied to chicken and beef liver tissues. The reliable limit of sensitivity is 100 ppb, but 10 ppb can be detected. This technique can be used to semiquantitate monensin in tissues by comparing the zones of inhibition of unknown test samples against monensin standards.
Elimination of Aliquoting in Automated Flame Photometric Determination of K2O in Fertilizers
Authors: Steele Layna D , Ramsey Kelly J , Kane Peter F
Published: February 2020

Current automated instrument systems used in conjunction with the official AOAC flame photometric method for K2O in fertilizer, 2.D06, all require a dilution step to bring the fertilizer extract to the appropriate concentration range. Two CFA (Continuous Flow Analysis) automated instrument systems are described which together eliminate aliquoting over the full range of fertilizer potassium, a significant saving of analyst effort if large numbers of samples are analyzed. The systems have performance characteristics well within the limits in the official method, and produce results comparable to current methods on routine samples.
Rapid Determination of Color Additives, Using the C18 Cartridge
Authors: Young Mary L
Published: February 2020

A reliable method has been developed for the rapid separation and identification of the 7 permitted FD&C dyes (Red Nos. 3 and 40; Blue Nos. 1 and 2; Yellow Nos. 5 and 6; Green No. 3) and the recently banned FD&C Red No. 2 in foods. The colors are separated by using the C18 cartridge, and their identity is confirmed by spectrophotometry.
Modified Flotation Technique for Quantitative Determination of Mite Populations in Feedstuffs
Authors: Thind Bharat B , Wallace David J
Published: February 2020

Modifications are described to a previously published technique for quantitative determination of mite populations in animal feedingstuffs. In the modified method, the oil phase is kerosene instead of a mixture of kerosene and tetralin (1 + 1), and aqueous industrial methylated spirit is substituted for aqueous ethanol in the aqueous phase. Emulsion formation at the interface is considerably reduced by incorporating a pre-extraction stage. Examination of mites on the filter paper is made easier and quicker by staining them with Phloxin B. Trials carried out with known numbers of mites in samples of dairy feed concentrates indicate mean recoveries of 84-96% throughout the range tested. The results show that the accuracy of the technique is not affected by the level of infestation.
Comparison of HgO and CuS04 as Digestion Catalysts in Manual Kjeldahl Determination of Crude Protein in Animal Feeds: Collaborative Study
Authors: Kane Peter F ,   Collaborators:, Altemeier A , Austin L L , Beggs C V , Cathey R D , Grant R , Hester J B , Hudson S , Johnson W C , Krause J , Midkiff V , Morris H F , Mueller E E , O’Neil M , Perry W V , Smith R D , Stedman R , Steele L D , Tulloch R N , VanDeKoppel G , Vickery R M , Willkens G , Williams D C
Published: February 2020

The official AOAC manual Kjeldahl method for determining crude protein in animal feeds, 7.015, uses HgO as a catalyst in the digestion step. Because of environmental considerations, there is considerable interest in alternative catalysts. A collaborative study compares the official HgO-catalyzed method and an alternative using CuS04. Fifty-four samples consisting of blind duplicates of closely matched pairs, representing a range of animal feed materials and 2 standard materials, were analyzed once by each method. Results were returned by 22 laboratories. Means and standard deviations between methods were comparable. The CuS04-catalyzed method has been adopted official first action.
Liquid Chromatographic Determination of Acetic Acid in Foods
Authors: Ashoor Samy H , Welty Jim
Published: February 2020

A liquid chromatographic (LC) method has been developed for the determination of acetic acid in vinegar and other foods. The LC system includes an Aminex HPX-87H column and a UV detector set at 210 nm. The mobile phase is 0.009N H2S04 at a flow rate of 0.7 mL/min. The method is simple and specific for acetic acid. Recoveries of acetic acid from a variety of products ranged from 93.3 to 102% with coefficients of variation from 2.4 to 4.6%.
Identification of a Propantheline Analog in Propantheline Bromide Tablets
Authors: Ford Bruce L , Wall Andrew K , Johnston Michael A , Lea Anthony R
Published: February 2020

A major impurity in a sample of propantheline bromide tablets has been identified as 9-hydroxypropantheIine on the basis of the proton magnetic resonance (PMR) and mass spectra (MS). This identification was confirmed by methanolysis of the tablet extract, which yielded a mixture of methyl xanthanoate and methyl 9-hydroxyxanthanoate. A liquid chromatographic (LC) procedure is described which will permit quantitation of 9-hydroxypropantheline bromide in the presence of propantheline bromide, xanthone, and xanthanoic acid.
Detection of Escherichia coli Enterotoxins by Using Mouse Adrenal Cell and Suckling Mouse Assays: Collaborative Study
Authors: Lovett Joseph , Peeler James T ,   Collaborators:, Boutin B K , Cholensky J S , Edwards A W , Ferreira J L , Hunt J M , Kaysner C A , O’Brien K , Ruby R M
Published: February 2020

The ability of 10 Escherichia coli strains to produce heat-stable enterotoxin (ST) and heat-labile enterotoxin (LT) was determined by 8 analysts in a collaborative study. The suckling mouse model and the mouse adrenal cell line (Y-l) tests were used to detect ST and LT, respectively. Cultures for assay were grown 24 h in casamino acid-yeast extracttrace salts broth at 37°C in a shaker incubator at 250 rpm. Cell-free culture broth prepared by centrifugation and filtration was divided into 2 portions: One was heated for 30 min and used both for ST assay and as a heated control for LT assay; the other was used unheated for LT assay. Results were expressed as positive for ST, positive for LT, positive for ST and LT, or negative for both ST and LT; percent of correct estimates was calculated for each culture for each analyst. At the 95% confidence interval, the overall correct results were 96.3 ± 2.9 and 95.0 ± 3.4% for ST and LT, respectively. The test performances thus were satisfactory for detecting ST and LT produced in vitro by E. coli. The method has been adopted official first action.
Liquid Chromatographic Determination of Carbadox, Desoxycarbadox, and Nitrofurazones in Pork Tissues
Authors: Macintosh Agnes I , Neville George A
Published: February 2020

A liquid chromatographic (LC) method has been developed for the determination of carbadox, desoxycarbadox, and nitrofurazones in the 10-40 ppb range in pork muscle, liver, and kidney tissues. Tissues were homogenized in absolute ethanol, and the homogenates were treated with metaphosphoric acid and reduced in volume by rotovaporization. Hexane was added to the concentrates, which were then centrifuged to remove fat. After addition of KH2P04 to the aqueous phase and extraction with ethyl acetate, the extracts were passed through alumina columns before analysis by reverse phase LC. Overall average recoveries (10-40 ppb range) for carbadox and desoxycarbadox from spiked tissues were 53% ± 13.6 and 61% ± 7.2, respectively; overall average recoveries for nitrofurazone and furazolidone were 43% ± 7.3 and 77% ± 10.9, respectively. Before these optimum determinations, degradation by even minimal incandescent light was found to reduce recovery especially of desoxycarbadox. The results of this photochemical degradation are reported and briefly discussed.
Rapid Quantitation and Confirmation of Aflatoxins in Corn and Peanut Butter, Using a Disposable Silica Gel Column, Thin Layer Chromatography, and Gas Chromatography/Mass Spectrometry
Authors: Trucksess Mary W , Brumley William C , Nesheim Stanley
Published: February 2020

Asimple, rapid, and solvent-efficient method for determining aflatoxins in corn and peanut butter is described. Aflatoxins B1, B2, G1, and G2 were extracted from SO g sample with 200 mL methanol-water (85 + 15). A portion of the extract was diluted with 10% NaCl solution to a final concentration of 50% methanol, and then defatted with hexane. The aflatoxins were partitioned into chloroform. The chloroform solution was evaporated, and the residue was placed on a 0.5 g disposable silica gel column. The column was washed with 3 mL each of hexane, ethyl ether, and methylene chloride. Aflatoxins were eluted with 6 mL chloroform-acetone (9 + 1). The solvent was removed by evaporation on a steam bath, and the aflatoxins were determined using thin layer chromatography (TLC) with silica gel plates and a chloroform-acetone (9 + 1) developing solvent. Overall average recovery of aflatoxin B] from corn was 82%, and the limit of determination was 2 ng/g. For mass spectrometric (MS) confirmation, aflatoxin B1, in the extract from 3 g sample (20 ng/g) was purified by TLC and applied by direct oncolumn injection at 40°C into a 6 m fused silica capillary gas chromatographic column. The column was connected directly to the ion source. After injection, the temperature was rapidly raised to 250¯C, and the purified extract was analyzed by negative ion chemical ionization MS.
Quantitative Gas Chromatographic Headspace Determination of Choline in Adult and Infant Formula Products
Authors: Saucerman Janice R , Winstead Charles E , Jones Tom M
Published: February 2020

A gas chromatographic headspace method has been developed for the determination of choline in liquid and powder formula products. Choline undergoes the Hofmann elimination reaction during a 24 h, 120°C alkaline digestion. Volatile trimethylamine (TMA) is produced and equilibrates between the liquid and vapor phase (headspace). A 50 jiL headspace sample is chromatographed on a 28% Pennwalt 223-4% KOH column, with flame ionization detection. Choline is indirectly quantitated by comparing sample TMA peaks with peaks for a reference standard. Ethyl ether is used as an internal standard. Compared with previous methods, this procedure offers improved precision (7.7-9.6% relative standard deviation (RSD)), accuracy, and specificity of both free and bound forms of choline. Estimated analysis rate using manual injection is 160 samples/week, requiring 35 work-hours. Automation of this procedure, using a commercially available headspace analyzer, resulted in a further improvement in precision (1.60-6.91% RSD) and a throughput of 400 samples/week.
Inductively Coupled Plasma Emission Spectroscopic Determination of Nine Elements in Infant Formula: Collaborative Study
Authors: Suddendorf Ronald F , Cook Kathleen K
Published: February 2020

Results from a collaborative study of a method for the determination of 9 elements in infant formula, using inductively coupled plasma emission spectroscopy, are reported. Six collaborators analyzed 6 infant formulas for native and spiked levels of Ca, Cu, Fe, Mg, Mn, P, K, Na, and Zn. The within-laboratory and between-laboratory coefficients of variation were generally (69 of 108 samples) below 9% for all elements determined in all samples. Most of the average recoveries of the elements from spiked samples ranged from 90 to 105%. The method has been adopted official first action for determining Ca, Cu, Fe, Mg, Mn, P, K, Na, and Zn in infant formula.
Liquid Chromatographic Determination of Vitamin B-6 in Foods
Authors: Vanderslice Joseph T , Brownlee Stella R , Cortissoz Mariann E
Published: February 2020

Chromatographic analysis for vitamin B-6 in complex samples imposes certain requirements on the analyst, who must extract completely the bound, unstable vitamers without loss, remove interfering compounds, and provide clean extracts for analysis. The analyst also has to contend with the problems inherent in all methods, such as sample collection, storage, preparation, and homogenization. However, chromatography provides a means of identifying and quantitating all forms of the vitamin, and thus provides the possibility of addressing the problem of the bioavailability of specific vitamers. It also allows automation, which is absolutely essential in coping with the large numbers of samples that are generated in areas such as quality control. These factors are all addressed here, and chromatographic results for various meat and other food products are presented to illustrate the variations in vitamin content that occur from sample to sample, the agreement with microbiological results, and that liquid chromatography (LC) has come of age in dealing with complex biological samples, such as food and food products.
Liquid Chromatographic Determination of Hydroxymethylfurfural in Fruit Juices and Concentrates After Separation on Two Columns
Authors: Cilliers Johannes J L , Van Niekerk Pieter J
Published: February 2020

A liquid chromatographic (LC) method is described for the detection and quantitation of 5-hydroxymethyl-2-furaIdehyde (HMF) in fruit juices and juice concentrates. HMF is separated by chromatography in 2 dimensions with different reverse phase columns. The first column is eluted with aqueous solvents, 5% methanol-2.5% acetonitrile-1.5% tetrahydrofuran (1 + 1 + 1). By using an electrically driven, 6-port valve, the collected impure HMF fraction is rechromatographed on the second column with 5% aqueous methanol as mobile phase. The compound was detected at 284 nm under conditions selected to separate HMF in 26 min with very little or no sample preparation. On a series of samples, this method gave lower values than did the colorimetric toluidine-barbituric acid method.
Gas Chromatographic Determination of Chlorpyrifos Residues in Greenhouse Vegetables After Treatment of Potting Media with Dursban for Imported Fire Ant
Authors: James Joyce P , Spence James H , Ford Joseph H
Published: February 2020

Residues of chlorpyrifos in vegetables were extracted in acetone, and then partitioned between 5% aqueous sodium sulfate solution and hexane to minimize the quantity of oily materials in the extract. Light green vegetable extracts were cleaned up on a silica cartridge, and dark green vegetable extracts were cleaned up with decolorizing carbon and silica gel column chromatography. Chlorpyrifos was determined by gas chromatography (GC) with electron capture detection. The vegetables analyzed were started as seedlings in potting soil treated with Dursban and were transferred to the field for maturation. Residue levels were determined in mature vegetables at the harvestable stage of growth, and ranged from < 0.01 ppm in vegetables, such as cabbage, squash, and tomato, to 0.06 ppm in parsley.
Arsenic, Cadmium, Lead, Mercury, and Selenium in Sediments of Riverine and Pothole Wetlands of the North Central United States
Authors: Martin Dan B , Hartman William A
Published: February 2020

Surface sediments (0-10 cm) collected in 1980 and 1981 from 13 wetland areas in Iowa, Montana, Nebraska, North Dakota, and South Dakota were analyzed for total concentrations of arsenic, cadmium, lead, mercury, and selenium. Sediments from pothole-type wetlands had significantly higher concentrations of arsenic, cadmium, lead, and selenium than those from riverine wetlands. Mean (and range) of dry weight concentrations (mg/kg) for pothole and riverine locations, respectively, were arsenic, 4.4 (1.4-9.3) and 2.4 (0.7-6.1); cadmium, 0.52 (0.17-0.87) and 0.26 (0.01-0.55); lead, 13 (7.4-22) and 6.6 (1.1- 14); selenium, 0.89 (0.13-2.1) and 0.52 (0.03-5.1). Mercury concentrations in sediment did not differ significantly between pothole and riverine type wetlands (mean, 0.03, range, 0.01-0.08). A comparison of the concentrations of elements found in this study with values reported in the literature indicated that, with the possible exception of one location, levels were within normal or background ranges.
Improved Gas Chromatographic Determination of Sorbitan Fatty Acid Esters in Confectionery Products
Authors: Tsuda Taizo , Nakanishi Hiroshi , Kobayashi Shigenobu , Morita Takashi
Published: February 2020

A method is described for gas chromatographic (GC) determination of sorbitan fatty acid esters in confectionery products as sorbitan monostearate. A sample is homogenized with chloroform, filtered, dried, and saponified with 0.1N NaOH in ethanol 1 h at 80°C. The saponification mixture is acidified, washed with hexane, and dried. Isosorbide, 1,4-sorbitan, and D-sorbitol are each derivatized at 70°C with pyridine, hexamethyldisilazane, and trimethylchlorosilane. GC separation of the polyols as TMS (trimethylsilyl) derivatives was performed on a 2% Dexsil 300 column temperature-programmed from 120 to 250°C at 107 min. The sorbitan monostearate content of the sample was calculated from the polyols, using the appropriate conversion factor. The procedure was applied to ice creams, cakes, and other confectionery products. Average recoveries from samples spiked with 1.0% Span 60 (sorbitan monostearate) were 91-96% for isosorbide, 83-99% for 1,4-sorbitan, and 82-98% for D-sorbitol. The detection limit was approximately 0.01%.
Normal Phase Liquid Chromatographic Determination of Sulfamethoxazole in Tablets:
Collaborative Study
Authors: Robinson John W
Published: February 2020

A stability-indicating liquid chromatographic method is presented for determining sulfamethoxazole in tablets. The method uses a 10 p.m silica column, an isooctane-methylene chloride-2-propanol-acetonitrile- glacial acetic acid (70 + 25 + 5 + 5 + 0.5) mobile phase, and photometric detection at 254 nm. Seven laboratories collaboratively studied this method on powdered composite samples prepared from commercial 500 and 1000 mg tablets and on an authentic tablet mixture containing 83.32% added sulfamethoxazole. Mean assay results for the 500 and 1000 mg tablets w ere 102.2 and 97.9% of declared, respectively (n = 4). The mean recovery value for the synthetic sample was 99.4% (n = 4). The pooled reproducibility standard deviation (SD) (coefficient of variation (CV) ) and pooled repeatability SD (CV) were ± 1.01 (1.01%) and ± 0.96 (0.96%), respectively. These results were in good agreement with those obtained by the Associate Referee for the titration method of USP XX. The proposed method can also be used for monitoring the presence of sulfanilamide in sulfamethoxazole by increasing the proportions of both acetonitrile and 2-propanol in the mobile phase. The method has been adopted official first action.
Validation of Liquid Chromatographic Method for Assay of Chlorthalidone in Tablet Formulations
Authors: Fogel Jerry , Sisco Jay , Hess Fritz
Published: February 2020

A stability-indicating, reverse phase liquid chromatographic (LC) method was developed for assay of chlorthalidone in tablet formulations. The chromatographic system separates the parent compound from its potential hydrolysis product (4'-chIoro-3'-sulfamoyl-2-benzophenone carboxylic acid), which can be quantitated at low levels, and another degradation product (2-chloro-5-(l-methoxy-3-oxo-l-isoindolinyl)benzenesulfonamide), which was found during the experimental work. The procedure can also be used for content uniformity determinations. The general utility of the method was demonstrated by the assay of several product brands. The validated procedure was shown to be accurate, precise, reproducible, and specific.