bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential Determination of Furfural and Hydroxymethylfurfural by Derivative Spectrophotometry
Authors: Mansilla Espinosa A , Salinas F , Nevado Berzas J J
Published: February 2020

Derivative spectrophotometric methods have been developed for determining furfural and hydroxymethylfurfural and for resolving their binary mixtures on the basis of the UV spectra and the Winkler reaction. The latter method permits the simultaneous determination of both compounds in orange and grapefruit juices without previous separations.
Modified Colorimetric DNA Hybridization Method and Conventional Culture Method for Detection of Salmonella in Foods: Comparison of Methods
Authors: Foster Kim , Garramone Susan , Ferraro Karen , Groody E Patrick
Published: February 2020

A new, improved colorimetric DNA hybridization method for detection of Salmonella in food was developed. A new modified Colorimetric GENETRAK ® Salmonella Assay (m-DNAH) is similar to the current Colorimetric GENE-TRAK Salmonella Assay (c-DNAH) except that the number of assay steps has been reduced, indicator dyes have been added to some reagents to facilitate the tracking of reagent additions, and the probe set has been modified so that subgenus V Salmonella can be detected. The new probe set detected 453/453 Salmonella strains representing at least 239 serovars and 50 somatic antigen groups, including 8 strains of subgenus V Salmonella that were not detected by the current probe set. In addition, a total of 225 nonsalmonellae representing highly homologous organisms such as Enterobacter agglomerans, Escherichia coli, and Citrobacter freundii were all nonreactive with the modified probe set. Overall, a comparison of m-DNAH to the conventional Bacteriological Analytical Manual/AOAC culture method using 240 inoculated food samples and 80 naturally contaminated raw poultry samples showed that both methods were equally effective for detecting Salmonella in food products. The method has been adopted first action by AOAC International to replace method 990.13.
Equivalency of Gas Chromatographic Conditions in Determination of Nicotine in Environmental Tobacco Smoke: Minicollaborative Study
Authors: Ogden Michael W
Published: February 2020

Alternative gas chromatographic (GC) conditions were collaboratively studied for equivalency with conditions specified in the official AOAC method 990.01 for nicotine in environmental tobacco smoke (ETS). Test conditions under evaluation were the use of a 30 m x 0.32 mm id fused silica capillary column with split injection as compared to the method-specified 30 m x 0.53 mm id fused silica capillary column with direct or on-column injection. The 6 samples analyzed in duplicate by 7 laboratories included 3 spiked samples (concentration ranging from 0.18 to 1.8 µ.g nicotine per sample) and 3 ETS samples (concentration in air ranging from 4 to 36 µg nicotine/cu m). Four laboratories used the AOAC approved GC conditions and 3 used the test conditions. Data analysis detected no difference in results (P= 0.72) obtained using either the 0.32 mm or 0.53 mm id column (and associated conditions). Average repeatability (RSDr) and reproducibility (RSDR) relative standard deviations for the 0.53 mm id column were 5.2 and 8.3%, respectively, for spiked nicotine samples, and 5.3 and 8.5%, respectively, for ETS samples. Average repeatability (RSDr) and reproducibility (RSDR) relative standard deviations for the 0.32 mm id column were 4.1 and 4.7%, respectively, for spiked nicotine samples, and 3.5 and 6.3%, respectively, for ETS samples. The method incorporating the use of the 0.32 mm id column and associated conditions is recommended for adoption as official first action.
Liquid Chromatographic Determination of Methylene Blue and Its Metabolites in Milk
Authors: Munns Robert K , Holland David C , Roybal José E , Meyer John G , Hurlbut Jeffrey A , Long Austin R
Published: February 2020

A method is described for the liquid chromatographic (LC) determination of trace levels of methylene blue (MB) and its metabolites in milk. The cleanup involves protein precipitation with acetonitrile, extraction into chloroform of MB and its metabolites (azure A [AZA], azure B [AZB], and azure C [AZC]), extraction by chloroform of thionin at pH 10, and solid-phase extraction on a disposable carboxylic acid column. LC separation and quantitation are performed with an isocratic acetonitrile-acetate buffer mobile phase on a cyano column. Average recoveries (5-20 ppb levels) of MB, AZA, AZB, and thionin from fortified milk were 83.2,60.0, 84.4, and 22.5%, respectively. Some incurred MB metabolites in milk are bound organically to a fraction of the milk substrate, whereas others are free demethylated forms of MB. Analysis of milk collected 8 h after administration of MB contained the following average levels (n = 6) of free MB and metabolites: MB, 31.0 ppb; AZA, 21.3 ppb; and AZB, 54.1 ppb. Depletion of free MB and metabolites AZA and AZB from milk after administration of MB to lactating cows occurred in less than 40 h. Metabolites of MB that formed complexes with organic compounds were hydrolyzed in part to the free forms. The leuco form of MB cou
Gas Chromatographic Methods for Doxepin Isomers, Related Compounds, and Organic Volatile Impurities in Raw Materials and Doxepin Isomers in Capsules
Authors: Cyr Terry D , Lawrence Robert C , Lovering Edward G
Published: February 2020

Gas chromatographic methods have been developed for the determination of doxepin as the sum of the resolved E and Z isomers, 4 doxepin-related compounds, and organic volatile impurities in drug raw material. Minimum quantifiable amounts of the related compounds in raw materials are less than 0.05%. A method for assay of doxepin, as the total of the E and Z isomers, in capsules was also developed; relative standard deviation is less than 1% for the drug assay. Eleven raw material and 18 capsule samples were examined. No drug-related compounds or U.S. Pharmacopeia- or European Pharmacopeia-limited organic volatile impurities were detected in any of the samples.
Immunoassay of Ochratoxin A, Using Antibodies Developed Against a New Ochratoxin-Albumin Conjugate
Authors: Breitholtz-Emanuelsson Anna , Dalhammar Gunnel , Hult Karl
Published: February 2020

A derivative of ochratoxin A was linked to bovine serum albumin in such a way that the carboxylic group of ochratoxin A was left unmodified. Lysine was substituted for phenylalanine in ochratoxin A, and the ε-amino group was linked to the protein. The conjugate was injected into 2 rabbits; antibodies against ochratoxin A were developed and used to develop an indirect competitive enzyme-linked immunosorbent assay. The detection limits for ochratoxin A in incubation buffer were 0.07 and 0.02 ng ochratoxin A/mL with the 2 antisera, respectively. Three hundred human plasma samples were purified by a novel sample preparation method and were analyzed by the immunosorbent assay. The detection limits for ochratoxin A in plasma samples were 0.2 and 0.1 ng ochratoxin A/mL with the 2 antisera, respectively. The cross-reactivity of the 2 antiochratoxin A sera was high for the ochratoxin A methyl ester, about 20% for ochratoxin C, and low for (4R)-4-hydroxyochratoxin A, ochratoxin α, ochratoxin B, and 4-hydroxyochratoxin B. No cross-reactivity was seen for phenylalanine and lysine.
Liquid Chromatographic Determination of Pesticides in Finished Drinking Waters: Collaborative Study
Authors: Edgell Kenneth W , Erb Elizabeth J , Longbottom James E , Lopez-Avila Vlorica
Published: February 2020

A joint U.S. Environmental Protection Agency (EPA)/AOAC International collaborative study was conducted on EPA National Pesticide Survey Method 4, Determination of Pesticides in Finished Drinking Water by High Performance Liquid Chromatography with an Ultraviolet Detector, to determine mean recovery and precision for analyses of 18 pesticides and metabolites in reagent water and finished drinking waters. The study design was based on Youden's nonreplicate plan for collaborative studies of analytical methods. The waters were spiked with 18 pesticides and metabolites at 6 concentration levels, prepared as 3 Youden pairs. Ten volunteer laboratories extracted the spiked test waters with methylene chloride, performed a solvent exchange with methanol, and analyzed an aliquot of each extract by liquid chromatography using an ultraviolet detector at 254 nm. Results were analyzed using an EPA computer program that calculated recovery and precision for each of the 18 compounds and compared method performance between water types. The method was judged useable for all analytes tested. Recoveries were good for 16 of the analytes. The method exhibited poor recovery but acceptable between-laboratory precision for metribuzin DADK and metribuzin DK. The method performance statistics for carbofuran phenol and linuron were calculated to be significantly different for reagent water and finished drinking water. Similar statistical differences were observedfor metribuzin DADK, but these effects were not considered of practical significance due to the poor recovery (<25%) in both waters. In reagent water, the overall relative standard deviation (RSDR) range was 7.8-24.1% for all 18 compounds and 5.5-38.6% in finished drinking water. The single- analyst relative standard deviations (RSDr) range was 5.7-17.6% in reagent water and 4.0- 18.7% in finished drinking water. The method has been adopted first action by AOAC International.
Predicting the Environmental Distribution of Compounds with Unknown Physicochemical Properties from Known Pesticide Properties
Authors: Prasad Surya S
Published: February 2020

Disposing of pesticides improperly can have environmental consequences. This study examines those properties discussed in published literature or derived from semiempirical mathematical models that are most likely to affect pesticides' environmental distribution, then assesses their migration between environmental media (soil, water, air, and biota). In particular, it examines how pesticide characteristics such as water solubility, molecular weight, bioconcentration, volatility, and soil adsorption affect soil-to-water mobility, water-to-air dissipation, and water-to-biota accumulation when present in the environmental medium of preferred residence. The study concludes that chemicals that have low water solubilities tend to adsorb to soil, those that have low vapor pressures tend to dissipate slowly from water, and those that have relatively high octanol-to-water partition coefficients or low water solubility have a high potential for bioconcentration. Under these situations, environmental restoration might best be achieved by removal of the contamination at the source. By drawing analogies from these findings, researchers should be able to predict the mobility of pesticides belonging to a particular category or family of compounds with unknown physicochemical properties, determine the harm that might result from their distribution under worst-case scenarios, and recommend ways to restore the environment. Received
Using Experimental Design To Optimize a Microbial Diffusion Assay
Authors: Renard Laurent , Moulin Gerard , Sanders Pascal
Published: February 2020

As a prerequisite to validation of the cylinder plate diffusion assay for the antibiotic colistin sulfate in plasma, the assay needed to be optimized. Bordetella bronchiseptica (ATCC 4617) was the test organism for optimization. Ionic strength of buffer, quantity of test organism, duration of prediffusion, and volume of agar layer were studied. The effects of each factor were examined according to an experimental design. A 4 h prediffusion at 4°C increased sensitivity. Repeatability was improved by using 100 mL agar per bioassay dish, dilution of the plasma with buffer (3 + 1), and prediffusion. The slope of the standard response line was steeper with prediffusion. The reduced quantity of test organism contributed to better sensitivity and good repeatability. No significant interaction between these factors was found. Experimental designs were used successfully to rapidly set up a microbial method requiring a limited number of runs
Effect of Cold-Temperature Storage on Stability of Benzylpenicillin Residues in Plasma and Tissues of Food-Producing Animals
Authors: Boison Joe O , Korsrud Gary O , Macneil James D , Yates William D G , Papich Mark G
Published: February 2020

A recently developed liquid chromatographic method is used to determine benzylpenicillin residues in incurred tissue and plasma samples from experimental animals stored at freezer temperatures of -20°C and -76°C. It was observed that penicillin- incurred plasma samples stored at -20°C for 2 months were relatively stable, showing a gradual loss of only 10-20% of the residues present at the beginning of the storage period. Loss of penicillin residues from bovine kidney and liver stored at -20°C occurred at a rate that was more rapid than from plasma. Losses in benzylpenicillin concentrations of up to 20% were observed in kidney and liver samples stored at -20C after as little as 10 days of storage. Gluteal muscle samples stored at the same temperature showed almost 50% reduction in benzylpenicillin concentration after only 10 days of storage. However, incurred tissue samples stored at -76°C remained stable. The depletion of benzylpenicillin residues from edible tissues and biological fluids follows a first-order rate law.
Liquid Chromatographic Method for the Simultaneous Analysis of Sulfadimethoxine and Ormetoprim in Animal Feeds
Authors: Duke Paul D , Weiss George , Macdonald Alexander
Published: February 2020

An analytical method was developed to simultaneously determine sulfadimethoxine (SDM) and ormetoprim (OMP) in medicated animal feeds. SDM and OMP are extracted from the feed into methylene chloride at pH 10 following the addition of tetrabutylammonium hydroxide to form an ion pair with SDM. After the methylene chloride extract is dried over sodium sulfate, an aliquot is purified by solid-phase extraction using a PrepSep silica extraction column. Both compounds are separated by liquid chromatography on an Ultrasphere ionpair column at 3°0C with UV detection at 275 nm. The average recoveries for OMP and SDM in feeds fortified between 0.01 and 0.5% total combined drug ranged from 96.4 to 101.4%, respectively. Replicate assays of typical feeds yielded coefficients of variation of 1.7-3.1%.
Incidence of Fungi in Shared-Use Cosmetics Available to the Public
Authors: Mislivec Philip B , Bandler Ruth , Allen Geraldene
Published: February 2020

A survey was conducted to assess both the potential health risk from shared-use cosmetics caused by microorganisms and the microbial efficacy of preservatives in cosmetics. Samples of 3027 shared-use cosmetic products were collected from 171 retail establishments nationwide. Fungi were present in 10.4% of the products, and 3.9% contained fungal pathogens or opportunistic pathogens. The 423 fungal isolates identified represented 33 genera and at least 69 species. A disproportionately large share of the fungal isolates were from eye products; fewer were from lip products. Pathogenic or opportunistic pathogens made up 32.2% of the fungal isolates. A slightly lower percentage of samples that contained preservatives had fungi, a fact suggesting that preservatives reduce the incidence of fungi in cosmetics. Results of this survey indicate potential microbiological problems concerning the safety of shareduse cosmetics.
Unified Procedure for the Determination of Antibiotics in Animal Feeds
Authors: Salvatore Michael J , Katz Stanley E
Published: February 2020

A new method was developed for the determination of antibiotics in animal feeds. This qualitative and quantitative method can be applied to 17 antibiotics currently accepted for use in animal feeds. A solvent prewash step is used to differentiate groups of antibiotics and individuals of the same class of antibiotics and to remove interfering substances. Agarose gel electrophoresis at pH 6.0 and 8.0 is used to further differentiate the individual antibiotics and as an agar diffusion assay. Minimum detectable concentrations of antibiotics currently accepted for use in animal feeds were determined against selected microorganisms.
Gas Chromatographic/Chemiluminescence Detection (Thermal Energy Analyzer-Nitrogen Mode) Method for the Determination of Dibutylamine in Hams
Authors: Fiddler Walter , Doerr Robert C
Published: February 2020

A gas chromatographic (GC) procedure is described for the determination of dibutylamine (DBA) in ham at less than 1 ppm. Sample is extracted with 0.5N HCI, centrifuged, made basic, and then extracted with isopropyl alcohol. Final determination is by GC/thermal energy analysis in the nitrogen mode. Six replicate analyses of ham fortified with 0.5 ppm DBA gave a recovery of 90.2 ± 3.4%. Over a range of 0.5 to 3.0 ppm DBA, the repeatability was 0.07 ppm, and the coefficient of variation was 6.07%. Limit of detection was 01 ppm. Effectiveness of the procedure was demonstrated on selected ham samples.
Selective Determination of Methyl Mercury in Biological Samples by Means of Programmed Temperature Gas Chromatography
Authors: Lorenzo R A , Carro A , Rubí E , Casais C , Cela R
Published: February 2020

A programmed temperature gas chromatographic method is presented by which it is possible to carry out routine analysis of methyl mercury in biological samples prepared according to the AOAC official first action recommendations without the need for preliminary treatment of the columns. This method greatly extends the life of the columns as well as the useful time for analysis; it has good linearity and repeatability. With the proposed method a total of 36 samples can be analyzed daily.
Fractional Factorial Design Approach for Optimizing Analytical Methods
Authors: Oles Philip J
Published: February 2020

Experimental designs based on procedures of Taguchi are described for optimizing analytical methods. Methods were efficiently developed, with improvements in precision and accuracy, for the determination of cholesterol in foods, magnesium in feed premix, and moisture in mayonnaise. Significant factors and interactions were identified by using 2-level designs, analysis of variance techniques, and commercially available computer software. The designs were prepared by using Taguchi linear diagrams. The methods developed as a result of these experiments have proven to be rugged and reliable.
Performance of Two Immunochemical Assays in the Analysis of Peanuts for Aflatoxin at 37 Field Laboratories
Authors: Dorner Joe W , Blankenship Paul D , Cole Richard J
Published: February 2020

A study was conducted to measure the precision of 2 rapid aflatoxin assay systems in use at 37 peanut buying points during the 1991 harvest season. Aflatoxin laboratories were established at the 37 buying points to analyze peanut samples from all incoming farmers’ stock loads as part of a joint project sponsored by various segments of the U.S. peanut industry and the U.S. Department of Agriculture. Eighteen laboratories were equipped with Neogen’s veratox FSP rapid assay system, whereas 19 laboratories used Vicam’s Aflatest rapid assay system. To monitor the performance of the field laboratories during the project, 3 portions of each of six 27 kg samples of ground peanuts were sent to each laboratory for analysis over a period of 6 weeks. Aflatoxin concentrations ranged from 0 to 300 ng/g when eight 200 g subsamples of each sample were analyzed by liquid chromatography (LC). For the 5 samples contaminated with aflatoxin, relative standard deviations for repeatability (RSDr) for laboratories using veratox FSP ranged from 18.66 to 53.29%, and the relative standard deviations for reproducibility (RSDR) ranged from 22.79 to 59.29%. For laboratories using the Aflatest system, RSDr values ranged from 18.70 to 41.48%, and RSDR values ranged from 23.84 to 47.56%. Horwitz ratios < 2.0 were found for 4 of the 5 contaminated samples for both methods, indicating that the overall precision of the 2 methods used in the project was good. Mean aflatoxin concentrations, as determined with the rapid assay systems, were generally lower than those determined by LC, particularly for more highly contaminated samples. This could not be attributed to instability of aflatoxin in peanut paste, because additional information gathered in the study indicated that the stability of aflatoxin in peanut paste stored for 58 days was good.
Comparison of Methylation Methods for the Quantitation of Conjugated Linoleic Acid Isomers
Authors: Shantha Nalur Chandrasekaran , Decker Eric Andrew , Hennig Bernhard
Published: February 2020

Four methylation methods were evaluated for use in the gas chromatographic (GC) quantitation of conjugated linoleic acid (CLA) isomers, which are potential anticarcinogen. The methods were (1) sodium methoxide in methanol (NaOMe-MeOH), (2) American Oil Chemists' Society (AOCS) procedure Ce 2-66, which involves methanolic sodium hydroxide followed by boron trifluoride in methanol, (3) tetramethylguanidine in methanol (TMG-MeOH), and (4) direct transesterification with methanolbenzene- acetyl chloride (DAC). Purified methyl esters of isomerized linoleic acid containing 86% CLA isomers were methylated and analyzed by GC. The AOCS and DAC methods resulted in 3 and 50% losses in cis-9,trans-11-octadecadienoic acid (9c, 111 CLA isomer) and trans-10,cis-12 octadecadienoic acid (10t, 12c CLA isomers), respectively. Compared with the control, the AOCS and DAC methods increased the yield of the trans,trans CLA isomers (trans-9,trans-11- and trans-10, trans-12-octadecadienoic acid) by 1.07-fold and a 10-fold, respectively. A non-CLA artifact that eluted close to CLA peaks was formed during methylation by the AOCS and DAC methods. Thus, the DAC and AOCS methods are not suitable for quantitation of CLA isomers. The NaOMe-MeOH and TMG-MeOH methods, however, are suitable for quantitation of CLA isomers in fats containing low concentrations of free fatty acids.
Depletion of the Monoamino Metabolites of Zoalene During Frozen Storage
Authors: Parks Owen W
Published: February 2020

3-Amino-5-nitro-o-toluamide and 5-amino-3-nitro-o-toluamide, the principal metabolites in the tissues of chickens fed a diet containing Zoalene (3,5- dinitro-o-toluamide), were shown to deplete in frozen liver tissues stored up to 1 year at -20°C, but not at -70°C. A slight loss of 5-amino-3-nitro-otoluamide also occurred in thigh muscle at -20°C. Evidence is presented that demonstrates that the depletion of the metabolites was partially the result of their transformation to glucopyranosyl derivatives; both the α- and β-anomers of the 5-amino-3-nitro-otoluamide conjugate were observed in liquid chrcmatograms of tissue extracts.
Simultaneous Determination of Flavor Enhancers Inosine 5´-Monophosphate and Guanosine 5´-Monophosphate in Food Preparations by Derivative Spectrophotometry
Authors: Durán-Merás Isabel , Salinas Francisco , Peńa Arsenio Muńoz de la , Rόsas Miguel Lopez
Published: February 2020

A derivative spectrophotometry method was developed for the quantitative determination of 2 flavor enhancers, inosine 5´-monophosphate (IMP) and guanosine 5´monophosphate (GMP), in the presence of monosodium glutamate (MSG). Procedures for determining IMP and GMP singly and in binary mixtures are described. Overlapping absorption spectra of both compounds were resolved by using first-derivative spectrophotometry. By measuring the first-derivative signals of IMP and GMP at 253 and 248 nm, respectively, simultaneous determination was possible for IMP and GMP at 5–40 μg/mL, in the presence of up to 5000 μg/mL MSG. The method was satisfactorily used to determine IMP and GMP in several food preparations.
Gas Chromatographic/Mass Spectrometric Determination of Benzene in Nonstick Cookware and Microwave Susceptors and Its Migration into Foods on Cooking
Authors: Jickells Sue M , Philo Mark R , Gilbert John , Castle Laurence
Published: February 2020

Benzene in poly(tetrafluoroethylene) (PTFE) coatings of nonstick cookware was determined by heating a small amount of coating in a sealed vial. Gas chromatography/mass spectrometry (GC/MS) was used to analyze the vial headspace for benzene. A small survey (26 samples) of retail nonstick cookware detected benzene ranging from 2 to 50 μg/dm2 in 7 samples. Nonstick frying pans with various polymer coatings were obtained directly from 1 manufacturer. Benzene (6–30 μg/dm2) was detected in a number of these samples and was attributed to the use of a phenylmethyl silicone ingredient that contained benzene at 360 mg/kg. To determine the possible transfer of benzene from these coatings during normal use, several foods (puddings, cakes, and roast potatoes) were prepared in previously unused cookware. The foods were analyzed by using static headspace GC/MS. Benzene was not detected in any of these foods at a limit of detection of 2 μg/kg. In related studies, the determination of benzene release from microwave susceptors was performed by heating the materials in a sealed system at 190PC for 4 min. Benzene release above 1 μg/dm2 was not detected in 24 samples of susceptors. However, 1 specially supplied sample of nonmetallized susceptor released 10 μg/dm2 benzene when heated above normal anticipated temperatures of usage (to 220°C). Foods such as french fries and pizza when cooked according to the manufacturer’s instructions in susceptors contained no benzene with a limit of detection of 2 μg/kg. Even under abuse conditions of susceptors, the transfer of benzene to foods remained below this limit.
Optimization of Experimental Conditions for the Supercritical Carbon Dioxide Extraction of Pesticide Residues from Grains
Authors: King Jerry W , Hopper Marvin L , Luchtefeld Ronald G , Taylor Scott L , Orton William L
Published: February 2020

The efficiency of a supercritical carbon dioxide extraction system was investigated for the extraction at different pressures and temperatures of fortified grain samples containing organochlorine, organophosphorus, and organonitrogen pesticides from grain matrixes. The extractor unit was constructed using a gas booster pump and a Florisil sorbent trap for extracting and isolating the residues of interest. Using 20 g samples, extractions were performed between 40° and 80° C with pressures from 2000 to 10 000 psig. In most cases, pesticide recoveries exceeding 80% were recorded over the above range of temperature and pressure. Excellent recoveries and precision were recorded for an incurred methyl chlorpyrifos residue at the 0.043 ppm level. An improved liquid chromatographic assay was also developed for the analysis of carbofuran in grain samples.
Automated Beer Analyzer Method for Determination of Alcohol Content and Original Gravity of Beer: Summary of Collaborative Study
Authors: Gales Peter W , Schwiesow Mark
Published: February 2020

Two collaborative studies were conducted by the American Society of Brewing Chemists (ASBC) to evaluate use of an automatic beer analyzer for determination of alcohol content and original gravity of beer. Repeatability and reproducibility values obtained in the first study were satisfactory. The second study compared the automated method with the ASBC distillation method. Results by the 2 methods were similar; however, repeatability and reproducibility were better for the automated method. The automated method was adopted first action by AOAC International as an ASBC–AOAC method.
Sensitive Determination of Zearalenone and α-Zearalenol in Barley and Job's-Tears by Liquid Chromatography with Fluorescence Detection
Authors: Tanaka Touicm , Teshima Reiko , Ikebuchi Hideharu , Sawada Jun-Ichi , Terao Tadao , Icmnoe Masakatsu
Published: February 2020

A sensitive and reliable method for liquid chromatographic (LC) determination of zearalenone and α-azearalenol in barley and Job's-tears was investigated. The method by which these toxins were determined involves addition of an internal standard (zearalenone 6'-oxime) to barley and Job's-tears samples. Extracts from grain samples were cleaned up by passage through chromatography on piperidinohydroxypropyl Sephadex LH-20 as a lipophilic gel. Individual toxins were resolved by LC on a reversed-phase (ODS) column with fluorescence detection. The detection limit is estimated to be 0.2 ng for zearalenone and α-zearalenol standards. Known amounts of zearalenone and α-azearalenol (25-1250 ng) were added to a barley sample (5 g). Average recoveries for α-zearalenol and zearalenone, respectively, ranged from 96 to 102% (mean CV, 3.6%) and from 96 to 103% (mean CV, 3.3%). This method is applicable to determination of α-zearalenol and zearalenone in barley and Job's-tears with satisfactory sensitivity and accuracy.
The Chinese Total Diet Study in 1990. Part I. Chemical Contaminants
Authors: Chen Junshi , Gao Junquan
Published: February 2020

The Chinese total diet study in 1990 estimated the dietary intake of 24 chemical contaminants and 72 nutrients from 4 market baskets collected and prepared in 12 provinces. Twelve food group composites were made for each regional market basket. The overall dietary Pb, Cd, Hg, hexachlorocyclohexane HCH, and DDT intakes were well below their corresponding acceptable daily intakes. However, the Pb content of eggs from the 2 southern regions exceeded the tolerance limit. The Hg content of legumes just reached the tolerance limit, and Hg in eggs from the North 1 region exceeded the tolerance limit. The dietary HCH intake has decreased significantly since the 1980s, but dietary DDT intake has decreased rather slowly. Five organophosphorus pesticides were detected out of a total of 12 organophosphorus pesticides analyzed. Among them, methamidophos was the most outstanding. The intake of total committed dose equivalents (CDEs) of the 6 radionuclides was 0.24 mSv/a; only 1.5% was accounted for by 90Sr and 137Cs. 210Pb, 210Po 226Rg 228Ra accounted for 98.5% of the total CDEs. The main food sources of those radionuclides were cereals, vegetables, and aquatic foods. Aflatoxin B1 was detected at very low levels only in the cereal composite of the North 1 region. Aflatoxin M1 was not detected in any of the milk and milk products. The overall results show that there is no significant environmental contamination of the average Chinese diet.
Survey of Benzene in Foods by Using Headspace Concentration Techniques and Capillary Gas Chromatography
Authors: Mcneal Timothy P , Nyman Patricia J , Diachenko Gregory W , Hollifield Henry C
Published: February 2020

Recently, the combination of sodium or potassium benzoate with ascorbic acid was shown to produce low levels (ng/g) of benzene in fruit-flavored soft drinks. The presence of benzene also was reported in butter, eggs, meat, and certain fruits; levels of these findings ranged from 0.5 ng/g in butter to 500-1900 ng/g in eggs. Because benzoates are widely used as food preservatives, a limited survey of other foods containing added benzoate salts was conducted to investigate the potential for benzene formation. Selected foods that did not contain added benzoates but were previously reported to contain benzene were analyzed for comparison. More than 50 foods were analyzed by purge-andtrap or static headspace concentration and capillary gas chromatography. Benzene was quantitated by using the method of standard additions, and its identity was confirmed by mass selective detection. Results of this limited survey show that foods without added benzoates (including eggs) contained benzene at levels equal to or less than 2 ng/g. Slightly higher levels were present in some foods and beverages containing both ascorbic acid and sodium benzoate.
Liquid Chromatographic Determination of Moxidectin Residues in Cattle Tissues and Confirmation in Cattle Fat by Liquid Chromatography/Mass Spectrometry
Authors: Khunachak Alisa , Dacunha Adrian R , Stout Steven J
Published: February 2020

Moxidectin, a potent new endo- and ectoparasitic agent, is determined in cattle tissues by liquid chromatography (LC) with fluorescence detection. Moxidectin residues in cattle fat are confirmed with thermospray LC/mass spectrometry (MS). Moxidectin is extracted from the tissue with acetonitrile; the extract is partitioned with hexane, concentrated, and reacted with acetic anhydride, 1-methylimidazole, and dimethylformamide to produce a fluorescent product. The validated sensitivity of the LC/fluorescence method was 10 ppb, with a limit of detection typically between 1 and 2 ppb. Average recoveries from cattle fat, muscle, liver, and kidney were 99,95,89, and 92%, respectively. LC/MS confirmatory method determined the underivatized parent compound following the acetonitrilehexane partitioning step, with an average recovery of 108% at the 250 ppb level in cattle fat.
Comparison of Gel Permeation Chromatography, Sweep Codistillation, and Florisil Column Adsorption Chromatography as Sample Cleanup Techniques for the Determination of Organochlorine Pesticide Residues in Animal Fats
Authors: Armishaw Paul , Millar Roderick G
Published: February 2020

Methods using a commercial sweep codistillation apparatus, gel permeation chromatography (GPC), and Florisil column adsorption chromatography were compared as cleanup techniques for the determination of organochlorine pesticide residues in animal fats by Megabore capillary gas chromatography with electron capture detection. Animal fat that had been previously found to contain no detectable organochlorine residues was spiked with 17 organochlorine pesticides at levels ranging from 0.1 to 0.4 mg/kg and cleaned up by each of the 3 techniques. Recoveries obtained for all 3 methods were in the range 73-113%, with coefficients of variation between 1.1 and 11.2%. Equivalence of method performance was further demonstrated by performing replicate analyses of beef and sheep fat containing naturally incurred residues of heptachlor epoxide, dieldrin, p,p′-DDE, p,p′-DDD and p,p′-DDT. All 3 methods offer effective cleanup and acceptable recovery of organochlorine pesticides in animal fat. The sweep codistillation method has the advantages of low solvent and reagent use, simultaneous cleanup of 10 samples, and rapid turnaround, although thermal degradation of p,p′-DDT requires monitoring and control. GPC offers a high degree of automation but is a relatively slow sequential sample cleanup with high solvent use. Florisil column adsorption chromatography is a simple, proven technique but requires considerable solvent and reagent and has a low potential for automation.
Determination of Pyrethroid Residues in Vegetables, Fruits, Grains, Beans, and Green Tea Leaves: Applications to Pyrethroid Residue Monitoring Studies
Authors: Nakamura Yumiko , Tonogai Yasuhide , Tsumura Yukari , Ito Yoshio
Published: February 2020

Determination of natural pyrethrins and 12 synthetic pyrethroids in agricultural products was investigated. Vegetables and fruits were extracted with acetone, filtered after addition of coagulating solution, partitioned into n-hexane, and cleaned up on a Florisil column (as necessary). Pyrethroids were determined by gas chromatography/electron capture detection (GC/ECD) by using a methyl silicone-coated fused-silica capillary column, and recoveries were calculated by summing peak areas of the components. GC/mass spectrometry was used to identify the pyrethroids detected by GC/ECD monitoring. Grains and beans containing lipids were analyzed by extraction with acetonitrile, partition into n-hexane, Florisil column cleanup, and capillary GC/ECD. The coagulation method was suitable for nonfatty crops such as vegetables, fruits, and green tea leaves, because recoveries were good and Florisil column cleanup was not needed in most cases. The coagulation method was not applicable to lipid-containing crops such as grains and beans because of low recoveries. Recoveries for 18 crops at fortification levels of 0.25–1.0 ppm were 60.0–103.5%. No pyrethroids were detected from the nonfortified crops tested except green tea leaves, in which fluvalinate was detected at 0.89 ppm.
Determination of Ultratrace Levels of Lead in Infant Formula by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry
Authors: Thompson Joseph J
Published: February 2020

A simple method was developed for the accurate and precise determination of low- and sub-ppb (ng/g) concentrations of lead in infant formula by isotope dilution inductively coupled plasma mass spectrometry using ultrasonic nebulization. After addition of a known amount of 207Pb, samples were microwave digested and the ratio 207Pb/208Pb was measured in the digests. Agreement with certified values for lead in milk powder standard reference materials was good, and isotope dilution analysis using 206Pb yielded identical results for the standard reference materials. Lead concentrations determined for several infant nutritional products were verified by an independent method. Typically, relative standard deviations of <4% were obtained with this method for lead concentrations above 2 ppb. The recovery of 2 ng of lead from an aqueous standard carried through the microwave digestion was 104 ± 4%. Infant formula (containing 0.6 ppb lead) to which 0.4 ng of natural-abundance lead had been added, to simulate a formula containing 0.9 ppb lead, was analyzed by isotope dilution, and the result was 96 ± 18% of the theoretical value. Thus, differences of 0.3 ppb lead could be clearly distinguished, and the detection limit was estimated to be 0.1 ng lead per gram of infant formula. The keys to accuracy for this method are minimizing contamination and accurately determining the concentration of lead in the isotopically enriched standard.
Thin-Layer Chromatographic Detection of Organophosphorus Insecticides Containing a Nitrophenyl Group
Authors: Patil Vitthal B , Shingare Murlidhar S
Published: February 2020

A Griess reaction that has been used to detect organic compounds containing an aromatic amino group was used to detect organophosphorus compounds containing a nitrophenyl group, such as ethyl parathion, methyl parathion, and fenitrothion. On reduction with stannous chloride in HCI–water (1 + 1), these compounds give respective amino derivatives, which are further diazotized and coupled with 1-naphthylamine to give intense pink–orange spots. This reagent also gives a bluish to violet spot with p-nitrophenol, a metabolite of fenitrothion. The procedure can be used to detect these insecticides in biological materials in forensic toxicology.
Liquid Chromatographic Method for Determining the Percent of Olestra in Lipid Samples
Authors: Tallmadge Daniel H , Peter Y T Lin
Published: February 2020

A liquid chromatographic (LC) method has been developed to determine the percent of olestra in lipid samples. To achieve the highest degree of accuracy, this method requires the use of an olestra standard with the same molecular composition as the olestra in the lipid sample to be analyzed. Samples were analyzed by reversed-phase LC using an evaporative light-scattering detector. Chromatography was performed with a 5 μm octadecylsilane- Zorbax column that separates olestra from other lipophilic components. Three types of olestra standards (soybean-oil olestra, unheated cottonseed- oil olestra, and heated cottonseed-oil olestra), each analyzed in soybean oil, showed linearity when the amount of olestra injected ranged from 20 to 160 fig (r= 0.9996). The area under the olestra peak (retention time 3.5 to 4.9 min) was used to quantify the amount of olestra in olestra-lipid samples, by comparing the olestra area for the sample with that of the standard using a curve derived by linear regression. The method was evaluated using 3 types of olestra blended with soybean oil and varying the percent of olestra in the olestra-lipid blend from 5 to 90%. Recovery of olestra from these olestra-lipid blends varied from 99.2 to 106.0%, demonstrating excellent accuracy, with method precision expressed as the coefficient of variation, 0.9%. Each error estimate was derived from 5 parallel determinations. With proper validation (e.g., running an olestra-free blank for each lipid matrix), this method provides a rapid, accurate, and precise technique for measuring the percent of olestra in lipids extracted from olestra-formulated foods and in olestra-lipid blends.
Screening of Organochlorine Pesticide and Polychlorinated Biphenyl Residues in Nonfatty Seafood Products by Tandem Solid-Phase Extraction Cleanup
Authors: Schenck Frank J , Wagner Roberta , Hennessy Michael K , Okrasinski Joseph L
Published: February 2020

A rapid multiresidue solid-phase extraction (SPE) technique for the isolation and subsequent gas chromatographic (GC) determination of organo-chlorine pesticide and polychlorinated biphenyl (PCB) residues in nonfatty fish, crabmeat, shrimp, and scallops is described. Samples are extracted with acetonitrile, and the extract is subjected to a cleanup using both C18 and Florisil SPE columns. The residues are determined by GC with electron capture detection. Because the injected extracts are free from matrix interferences, the amount of residue present is easily calculated. The average recoveries of 9 spiked (0.01–0.40 ppm) organo-chlorine pesticide residues from 6 different seafood products ranged from 93.8 to 98.4%. The average recoveries of spiked (0.50 ppm) PCB mixtures from 4 different seafood products ranged from 88.5 to 107.2%. This SPE method and the AOAC multiresidue method for organochlorine residues in fish produced comparable results for nonfatty seafood samples containing incurred organochlorine pesticide and PCB residues. The SPE method reduces organic solvent consumption by 95% and hazardous waste by 85% compared with the AOAC method. We were able to carry 10 seafood samples through the extraction and cleanup in less than 2 h by using the SPE method.
Immunoaffinity Column Cleanup/Liquid Chromatographic Determination of Aflatoxins: An Interlaboratory Study
Authors: Barmark Anna-Lena , Larsson Kjell
Published: February 2020

Nine laboratories from Denmark, Finland, Norway, and Sweden participated in a collaborative study to evaluate an immunoaffinity column cleanup/liquid chromatographic determination of aflatoxins B and G. Samples of peanut, fig, maize gluten, soya expel-ler, and copra spiked with total aflatoxin concentrations ranging from 1.37 to 28.60 ng/g were distributed. Altogether, 13 samples were analyzed. Of these, 6 were pairs of blind duplicates, 1 was an unknown negative sample containing ¼0.1 ng/g, and 2 were practice samples. A statistical presentation of the results is given. Although the results obtained were individually corrected for recovery, they were lower than expected in most cases. In some cases, the recoveries were unacceptably low, particularly for aflatoxin G2. Relative standard deviations for method repeatability (RSDr) and reproducibility (RSDR) were good but generally better for the peanut and fig samples than for the others. Results were better for aflatoxins B1 and G1 than for aflatoxins B2 and G2. RSDR values varied from 9 to 35%, and RSDR values varied from 17 to 81%. Horwitz ratio values were >2.00 for 1 RSDR value and <1.00 for 23 of the 35 calculated RSDR values.
Determination of Ethyl Carbamate (Urethane) in Alcoholic Beverages Using Capillary Gas Chromatography with Thermal Energy Analyzer Detection: Collaborative Study
Authors: Dyer Randolph H
Published: February 2020

A gas chromatographic (GC) procedure for the determination of ethyl carbamate (urethane) in distilled spirits and wines using a thermal energy analyzer (TEA) system was collaboratively studied by 5 laboratories. Distilled spirits such as whiskey, brandy, gin, rum, and vodka containing low solids can be injected directly into the GC system without extraction. Liqueurs require extraction. Wine, beer, sake, and similar samples containing significant solids or other interferences are extracted prior to injection. The sample is analyzed by GC/TEA operating in the nitrogen mode with capillary column capability (30 m × 0.53 mm) and automatic injection. Helium is the carrier gas. The GC system is calibrated with a 100 ppb standard, followed by the samples. The concentration of ethyl carbamate is determined by multiplying peak area ratios by the concentration of the standard. For the distilled spirits, the recovery averaged 92%. The within-labora-tory repeatability (RSDr) ranged from 4.3 to 12.5%, with overall average of 8.0%, and reproducibility (RSDR) varied from 4.8 to 22.0%, with an overall average of 17.4%. For the wines, the recovery averaged 85%, and the RSDr ranged from 8.9 to 42.8%, with an overall average of 34.4%. The method has been adopted first action by AOAC INTERNATIONAL.
Salmonella Detection in Cocoa and Chocolate by Motility Enrichment on Modified Semi-Solid Rappaport-Vassiliadis Medium: Collaborative Study
Authors: de Smedt J , Bolderdijk R , Milas J
Published: February 2020

A collaborative study was performed in 13 laboratories (including the authors’ laboratories) to validate motility enrichment on modified semi-solid Rap-paport-Vassiliadis (MSRV) medium for rapid detection of motile Salmonella in cocoa powder and chocolate. The MSRV method was compared with the AOAC standard culture method for detection of Salmonella in cocoa powder, milk chocolate, sweet chocolate, and dark chocolate. Chocolate samples were artificially inoculated with Salmonella at 2 levels of contamination. Cocoa powder was inoculated at 2 levels with naturally contaminated dust from cocoa beans. Uninoculated control samples were also included for each type of product. The sensitivity rate was 98.1 % for the MSRV method and 94.9% for the AOAC culture method. The specificity rate was 100.0% for both methods. There was no significant difference in the proportion of samples positive by MSRV and the AOAC culture methods for any of the food types. The MSRV method has been adopted first action by AOAC INTERNATIONAL.
Detection of Adulteration in Apple Juice by L-Malic/Total Malic Acid Ratio: Collaborative Study
Authors: Elkins Edgar R , Heuser John R
Published: February 2020

L-Malic acid is the predominate acid in pure apple juice and no D-malic acid should be present. Synthetic malic acid contains 50% D-malic acid, is inexpensive, and can be used to create nonauthentic apple juice. L-Malic/total malic ratios of 0.9 or less are indicative of a nonauthentic sample. Fourteen laboratories participated in a collaborative study to determine the L-malic/total malic acid ratio in apple juice. Ten samples of apple juice were sent to each laboratory. Authenticity of the samples varied from 0 to 100%. The coefficients of variation in all cases were acceptable, i.e., ca 5%. The method was adopted first action by AOAC INTERNATIONAL.
Sensitivity of the Quick Color Test for Indicating Lead Release from Ceramicware
Authors: Dolan Scott P , Capar Stephen G , Jacobs Richard M , Plunkett Randall J , Hawkins George S
Published: February 2020

A quick color test (QCT) for indicating the presence of leachable Pb on ceramicware was evaluated as a screening tool. Fourteen sets of cups and mugs (197 pieces) of undecorated glazed ceramicware were tested. The QCT indicated the presence of leachable Pb on 95% of the cups and mugs at or above approximately 2 μg/mL. The QCT is an inexpensive and rapid qualitative test for Pb that can be conducted with a portable kit.
Determination of Aluminum in Wines by Direct Graphite Furnace Atomic Absorption Spectrometry
Authors: Larroque Michel , Cabanis Jean C , Vian Laurence
Published: February 2020

A simple method for direct routine determination of aluminum in wine by graphite furnace atomic absorption spectrometry is described. This procedure allows good sensitivity by inclusion of a cool-down step before atomization. The detection limit obtained with a single-beam apparatus was 1.5 μg/L. Recoveries of aluminum in red, white, and fortified wines ranged from 91.7 to 109.5%. Aluminum was determined in 98 red table wines from the south of France. The mean aluminum content was 0.763 mg/L (range, 0.25–2.55 mg/L). In addition, the ability of the wine to dissolve the aluminum in the crown cap was shown.