bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Sulfite in Foods and Beverages by Ion Exclusion Chromatography with Electrochemical Detection: Collaborative Study
Authors: Kim Hie-Joon
Published: February 2020

A liquid chromatographic (LC) method for determination of total sulfite in foods and beverages by alkali extraction followed by ion exclusion chromatographic separation and electrochemical detection (IEC-EC) was collaboratively studied by 9 laboratories. Blind duplicate samples of starch, diluted lemon juice, wine cooler, dehydrated seafood, and instant mashed potatoes were analyzed without spiking and with added sulfite at 2 levels. The initial sulfite levels varied from 0 to 384 ppm S02, and the levels added varied from 10 to 400 ppm. The initial sulfite levels determined by the IECEC method and the Monler-Williams method were in good agreement. Recovery of added sulfite by the IEC-EC method was generally higher than that by the Monler-Williams method. Within-laboratory repeatability (RSDr) for the IEC-EC method varied from 4.4 to 26.0%, and overall reproducibility (RSDR) varied from 8.5 to 39.3 %. The collaborators found the method to be fast, sensitive, and easy to use, which makes it a useful alternative to the Monler-Williams method. The method has been adopted official first action.
Determination of Free (pH 2.2) Sulfite in Wines by Flow Injection Analysis: Collaborative Study
Authors: Sullivan John J , Hollingworth Thomas A , Wekell Marleen M , Meo Victor A , Etemad-Moghadam Ali , Phillips John G , Gump Barry H
Published: February 2020

A method for the determination of free sulfite In wine by flow injection analysis (FIA) is described. The method Involves liberation of sulfur dioxide from the wine at pH 2.2, with detection by decolorlzation of a malachite green solution. The method was collaboratively studied, and the results indicated an average reproducibility of 12% for white wine samples (average level 12.1 ppm S02) and 26% for red wine samples (average level 3.1 ppm). When the FIA method was compared to an aeration/oxidation method, the results Indicated a high degree of correlation between the 2 methods. The FIA method has been adopted by AOAC official first action.
Gas Chromatographic Method for Determination of Chlorpyrifos and Its Metabolite 3,5,6-Trichloro-2-Pyridinol (TCP) in Dates
Authors: Mourer Charles R , Hall Gregory L , Whitehead William E , Shibamoto Takayuki
Published: February 2020

A method is described for the determination of the Insecticide chlorpyrifos and its metabolite TCP in green, unprocessed, and processed dates with the seeds incorporated. After extraction, chloropyrifos is cleaned up using Florisil and analyzed using a gas chromatograph (GC) equipped with a nitrogen/phosphorus detector. TCP is derivatized using bis- (trimethylsilyl)-acetamide (BSA) to form the TCP-derivative and analyzed by a gas chromatograph equipped with a Hall electrolytic conductivity detector. Recoveries of chlorpyrifos from all fortified dates (0.05 and 0.1 ppm) ranged from 86 to 110 % with an average of 94.5 %. Recoveries of TCP from all fortified dates (0.1 and 0.2 ppm) ranged from 79 to 99% with an average of 86%. Limits of detection for chlorpyrifos and TCP in green, unprocessed, and processed dates were 0.02 and 0.05 ppm, respectively.
Slurries Introduction in Flow Injection Atomic Absorption Spectroscopic Analysis of Sewage Sludges
Authors: Martinez-Avila R , Carbonell V , De la guardia M , Salvador A
Published: February 2020

The direct introduction of slurries in flow Injection-flame atomic absorption spectroscopy has been studied using a single-channel manifold. The influence of flow Injection parameters on the sensitivity and accuracy of this procedure has been established. A method has been developed for the determination of copper, manganese, and lead In sewage sludge where batch digestion of the samples In a microwave oven is carried out before dilution. Both sensitivity and limit of detection of the flow Injection analysis procedure are adequate for the analysis of actual samples (the limit of detection was 0.06, 0.05, and 0.3 ppm for copper, manganese, and lead, respectively). The accuracy of the proposed method, determined from the analysis of 2 reference samples from the European Community Bureau, is better than that obtained by the continuous aspiration of the samples.
Amino Acid Analysis of Feeds in The Netherlands: Four-Year Proficiency Study
Authors: Van Der Meer Jos M
Published: February 2020

To improve accuracy and precision of amino acid analysis In 12 Dutch feed laboratories, a proficiency study was organized twice annually over a 4-year period. The method used included reflux acid hydrolysis for 22 h followed by evaporation, separation on a cation-exchange resin In an amino acid analyzer, and photometric detection after post-column derlvatlzatlon with ninhydrln. For the determination of sulfurcontaining amino acids, samples were oxidized prior to hydrolysis. For the determination of tryptophan, samples underwent an alkaline hydrolysis excluding oxygen, were separated by liquid chromatography on a Hypersil ODS analytical column, and were assayed by UV or fluorescence detection. The average relative standard deviations within (CVr) and between (CVR) laboratories were 3 and 7%, respectively. For some mixed feed samples, the results from the proficiency study were compared with those obtained by the International Analytical Group. For those samples, the relative standard deviation of the difference between IAG and Dutch groups was only 1.9%. For samples that were analyzed twice during this 4-year period, relative standard deviation of between-serles differences was only 2.1 %.
Influence of Automatic Dishwashings and Scrubbings on Release of Lead from Glazed Ceramicware
Authors: Gould John H , Hight Susan C , Alvarez George H , Nelson Catherine E , Capar Stephen G
Published: February 2020

Use of lead glazes on ceramicware and the release of lead from finished glazes are reviewed. Single units of ceramicware with Initial lead leach levels from <0.1 to 470 /μg/mL were subjected to multiple automatic dishwashings with Intermediate scrubbing of the ware by plastic fiber pads. Ware was periodically leached with 4% acetic acid solution at room temperature for 24 h, and the solutions were analyzed for lead. Release of lead under these conditions Is discussed. Results Indicated that neither passive teachings nor multiple dishwashings and scrubbings can predict future lead-release characteristics of glazes and decorations.
Liquid Chromatographic Determination of Bromadiolone in Rodent Baits
Authors: Koppen Benny
Published: February 2020

A method Is described for the determination of bromadiolone in rodent bait formulations. Samples are Soxhlet-extracted using methanol as extractant and analyzed by reverse-phase liquid chromatography with UV detection at 280 nm. Chromatography is performed using a ODS-Hypersll (5 fim) column, which enables separation of the 2 diastereolsomers of bromadlolone. The sum of the peak areas of the diastereolsomers Is used for quantitation. The method was tested for precision, linearity, and recovery. Duplicate analyses of 10 formulation samples gave a mean relative standard deviation of 4.1%. Linearity was very good (correlation coefficient 0.9997) In the relevant concentration range. Recovery from spiked samples was 88.9 ±2.3%. The method is applicable to rodent bait formulations with bromadiolone content 0.005% and 0.01%.
Simplified Cleanup and Liquid Chromatographic Ultraviolet Determination of Linuron and Three Metabolites in Potatoes
Authors: Miliadis George E , Siskos Panayotis A , Vasilikiotis George S
Published: February 2020

A simple and efficient method Is presented for the extraction, cleanup, and liquid chromatographic (LC) determination of linuron and 3 of Its metabolites, 3-(3,4-dlchlorophenyl)-1- methyl urea (DCPMU), 3-(3,4-dlchlorophenyl) urea (DCPU), and 3,4-dlchloroanillne (DCA), in potatoes. Samples are extracted with acetone, partitioned into dlchloromethanehexane (1 + 1), and cleaned up using disposable silica cartridges. LC determination Is performed using a LIChrosorb NH2 5 pm column, with an Isopropanol-lsooctane gradient mobile phase and UV detection at 248 nm. Recoveries of linuron and 2 of the metabolites from untreated samples fortified at 0.02-2 jtg/g ranged from 80 to 102%, while recoveries for the metabolite DCA ranged from 60 to 78%. The detection limit was 0.015 jtg/g for linuron and each metabolite; the minimum quantitation level was 0.5 fig/g. The developed method was applied to potato samples from a field experiment
Improved Extraction of Atrazine and Metolachlor in Field Soil Samples
Authors: Huang Lee Q , Pignatello Joseph J
Published: February 2020

A method was developed for extraction of weathered residues of atrazine and metolachlor from field soils; soils had last been treated with commercial formulations of the herbicides 8-15 months prior to sample collection. Maximum yields were obtained by batch extraction at 75 °C for 2-16 h with methanol-water (80 + 20) In a sealed vial. Hydrolysis or other decomposition reactions were minor or negligible, depending on the extraction time. This method is an improvement over published methods that are validated by spike recoveries; the proposed method gives 1.7-1.8 times higher yields compared to shaking for 2 h at room temperature, and 1.3-1.8 times higher yields compared to Soxhlet extraction. The reproducibility of the method was better than 12%. The results underscore the Impact of nonequllibrlum sorption of organic compounds on analytical methodology and emphasize the need to validate extraction methods with field samples
Liquid Chromatographic Method for Determination of Explosives Residues in Soil: Collaborative Study
Authors: Bauer Christopher F , Koza Stephan M , Jenkins Thomas F
Published: February 2020

A collaborative study of a sonic extraction/liquid chromatographic method for determining nitroaromatic and nitramlne explosives In soil was conducted at 8 participating laboratories. Analytes HMX, RDX, TNB, DNB, tetryl, TNT, and 2,4-DNT were measured In duplicate for 4 field-contaminated soils and 4 spiked standard-matrix soils. Concentrations ranged from detection limits of about 1 μg/g to nearly 1000 μg/g. Results were evaluated with and without data Identified as outliers, which were often caused by electronic integrator miscalculation of chromatographic peak response. When outliers are excluded, method repeatability (within-laboratory relative standard deviation) for all analytes except tetryl Is less than 5% for spiked soils and less than 18% for fieldcontaminated soils. Relative standard deviation generally decreases as analyte concentration Increases. Reproducibility (between-laboratory relative standard deviation), except for tetryl and DNT, Is less than 7% for spiked soils and 26% for fleld-contamlnated soils. Thus, collaborators have nearly equivalent performance on spiked samples. For fleld-contamlnated soils, some additional Imprecision seems to result from the variability of extraction recoveries. Analyte recoveries from spiked soils are 95-97% for HMX, RDX, TNT, and DNT (similar to recoveries from aqueous samples); 92-93% for DNB and TNB; and 70% for tetryl. Poor results for tetryl (due to thermal degradation) are correctable If sonic bath temperatures are maintained near ambient. The method has been approved Interim official first action by AOAC.
Diagnostic Data Evaluation. Part V. Ruggedness "Stress" Test Evaluation
Authors: Malanoski Anthony J
Published: February 2020

A protocol was developed for "stress" method evaluation by a chemist with minimal knowledge of statistics. The protocol Identifies critical points using the ruggedness test design. An example of the diagnostic analysis as would be performed by the chemist was completed.
Enzymatic-Spectrophotometric Method for Determination of Cholinesterase Activity in Whole Blood: Collaborative Study
Authors: Harlin Karen S , Ross P Frank
Published: February 2020

Ten collaborating laboratories assayed 4 blind duplicate pairs of whole bovine blood for cholinesterase activity. The 4 sample pairs ranged from normal (100 %) to severely organophosphorus- lnhiblted (<10%) activity. Collaborators also received commercially available human lyophllized serum as an external control and a chromate solution to evaluate spectrophotometer performance. The Ellman kinetic assay was performed on a 1:1000 dilution of the whole blood In pH 8.0 phosphate buffer. The method monitors the increase in absorbance at 412 nm caused by formation of 5-thio-2- nltrobenzolc acid (yellow reaction product). Repeatability standard deviations (RSDr) ranged from 4.30 to 14.2%; reproducibility standard deviations (RSDR) ranged from 6.99 to 19.3 %. The lower limit of detection was estimated to be 0.10 μmole/mL/min. The method has been approved interim official first action by AOAC.
Gram-Negative Identification Card for Identification of Salmonella, Escherichia coli, and Other Enterobacteriaceae Isolated from Foods: Collaborative Study
Authors: Knight Michael T , Wood David W , Black James F , Gosney Ginger , Rigney Robert O , Agin James R , Gravens Carol K , Farnham Sheila M
Published: February 2020

Twelve laboratories evaluated the Gram-Negative Identification (GNI) Card to Identify members of the Enterobacteriaceae. Eighty-four Isolates, previously Isolated from foods, were used In the collaborative study; the Isolates represented 12 genera within the Enterobacteriaceae group. Each collaborator streaked each isolate on tryptlc soy agar plates for purity. In the method, plates are Incubated 18-24 h at 35 °C. Isolated colonies are then subcultured to tryptlc soy agar slants and Incubated 18-24 h at 35 °C. An emulsion Is made from the growth on the slant In 1.8 mL 0.45% sodium chloride solution. The GNI Card Is filled and placed In a reader/Incubator. Isolates are Identified and an identification Is printed. The Vltek System correctly Identified 96.7% of Salmonella sp., 97.0 % of Escherichia coll, and an average of 93.8% of the other enteric genera. The method using the Vitek System and GNI Card has been approved interim official first action by AOAC as a screening method for the presumptive identification of Salmonella sp., E. coll, and other Enterobacteriaceae isolated from foods.
Levels of 3,3',4,4'-Tetrachloroazobenzene in Diuron and Linuron Herbicide Formulations
Authors: Singh Joginder , Bingley Ron
Published: February 2020

Levels of 3,3',4,4'-tetrachloroazobenzene (TCAB) were determined by capillary gas chromatography (GC) with electron- capture detection (ECD) In 25 samples of diuron and linuron formulations obtained from the Canadian market. Acidic aqueous methanol was used to retain urea herbicide and the neutral TCAB was allowed to partition into hexane. Silica gel was used for cleanup of the hexane extract, followed by GC/ECO determination. Recovery data obtained at 4 different spiking levels (I.e., 0.3, 0.1, 1.0, and 5.0 ppm) In linuron averaged 93, 86, 85, and 97%, respectively. For diuron, spiking was done at 0.5,1.0, and 5.0 ppm levels and the corresponding average percent recoveries were 95,101, and 104. The TCAB contamination level observed in diuron on a 100% active Ingredient basis ranged from 0.15 to 3.38 ppm, whereas In linuron, it varied from 0.91 to 10.28 ppm.
Ion-Pairing Liquid Chromatographic Determination of Benzimidazole Fungicides in Foods
Authors: Gilvydis Dalia M , Walters Stephen M
Published: February 2020

A method Is described for determining residues in foods of thiabendazole, thlophanate methyl, the dl-oxygen analogue metabolite [dimethyl 4,4'-0-phenylene bis (allophanate)] that Is the metabolite name of the latter, and methyl-2- benzlmldazole carbamate, which Is the major metabolite and fungltoxlc principle common to both thlophanate methyl and benomyl. The residues are extracted from the product using methanol and are partitioned Into dlchloromethane after initial acidification and again after subsequent alkalinization of the extract. Residues are separated and quantified by reverse- phase liquid chromatography using an ion-pairing mobile phase with UV and fluorescence detectors In tandem. Recoveries from 7 different food crops fortified at 0.2-35 ppm levels ranged from 64 to 105%.
Mineralization Procedure for Determination of Copper in Aerosols Using Photometric Method Based on Copper-BPKQH Complex
Authors: Sanchez Francisco Garcia , Diaz A Navas , Medinilla J
Published: February 2020

A mineralization procedure Is proposed for copper aerosols In which samples are mineralized by wet-ashing with HN03 + HCIO4 mixture. Copper content Is determined by a photometric method based on formation of a complex between copper and benzyl 2-pyrldyl ketone 2-qulnolylhydrazone (BPKQH). The Influence of pH, ethanol content, and reagent concentration Is studied. Copper determination at pH = 7.3, In the range 0.05 to 3 ppm is proposed. Mineralization with HNO3 Is carried out In different conditions of evaporation (with or without dryness) and manipulation. Analysis of variance by the (ANOVA) single factor method shows that digestion conditions significantly Increase the variability of results. Repeatability assays suggest that nitric acid alone gives low precision. Recovery assays reveal that the HN03 digestion process causes copper loss by volatilization. Mineralization with HNO3 + HCIO4 is optimized on the basis of the accuracy and precision obtained. The ANOVA method suggests that mineralization conditions significantly Increase total variability of results and also that results of the photometric method are not significantly different from those of the AAS method. The optimum mineralization procedure gave an RSD of 0.63% and a copper recovery of 98.4%. The combined digestion and quantification method was applied to determination of copper In aerosol samples obtained during leaf spraying operations of olive trees In the field.
Fluorometric Determination of Alkaline Phosphatase in Fluid Dairy Products: Collaborative Study
Authors: Rocco Richard M
Published: February 2020

Official methods for the measurement of alkaline phosphatase (ALP) in dairy products use either phenyl phosphate or phenolphthaleln monophosphate as substrate. Quantitation of results requires butanol extraction of the Indophenol (Scharer) or 3-h dialysis of the liberated phenolphthaleln (Rutgers). The Advanced Fluorophos® assay Is based on a self-indicating substrate which, when acted upon by ALP, loses a phosphate radical and becomes a highly fluorescent compound. The rate of fluorophore formation Is monitored for 3 mln In a fluorometer and the enzyme activity In mU/L Is calculated. Eight laboratories participated in a collaborative study to evaluate the Fluorophos® assay for determining ALP activity In whole milk, skim milk, chocolate milk, and cream (half and half). The comparative method was the AOAC quantitative phenyl phosphate method, 16.121-16.122 (14th Ed.). Mixed herd raw milk was added to pasteurized samples at 0.05, 0.1, and 0.2% (v/v). Method performance at 0.1% (v/v) added raw milk as measured by repeatability and reproducibility standard deviations (sr and sR) and relative standard deviations (RSDr and RSDR), respectively, were: whole milk, sr = 21.7%, sR = 34.6%, RSDr = 4.4%, RSDR = 7.0%; skim milk, sr = 19.2%, sR = 31.4%, RSDr = 3.8%, RSDR = 6.2%; chocolate milk, sr = 27.6%, sR = 45.8%, RSDr = 5.3%, RSDR = 8.8%. The method has been adopted official first action by AOAC for determination of alkaline phosphatase in whole milk, skim milk, and chocolate milk.
Matrix Solid Phase Dispersion Isolation and Liquid Chromatographic Determination of Five Benzimidazole Anthelmintics in Fortified Beef Liver
Authors: Long Austin R , Malbrough Marsha S , Hsieh Lily C , Short Charles R , Barker Steven A
Published: February 2020

A multlresidue method for Isolation and liquid chromatographic determination of 5 benzimidazole anthelmintics (thiabendazole, oxfendazole, mebendazole, albendazole, and fenbendazole) in beef liver tissue is presented. Blank or benzlmldazole-fortlfled liver samples (0.5 g) were blended with octadecylsilyl derlvatlzed silica packing material (C18, 18% load, endcapped, 2 g). A column made from the C18/ liver matrix was first washed with hexane (8 ml_), following which the benzlmldazoles were eluted with acetonltrile. The acetonltrlle extract was then passed through an activated alumina column. The eluate contained benzimidazole analytes that were free from Interfering compounds as determined by UV detection (photodlode array, 290 nm). Correlation coefficients of standard curves for Individual benzlmldazoles Isolated from fortified samples, using internal standardization, were linear (0.996 ± 0.002 to 0.999 ± 0.001) with average relative percentage recoveries from 62.0 ± 6.7 to 86.8 ± 8.6% for the concentration range (100- 3200 ng/g) examined. The interassay variability was 7.0 ± 4.1 to 12.9 ± 10.2% with an Intra-assay variability from 2.2 to 4.0%.
Liquid Chromatographic Determination of Naproxen and Related Compounds in Raw Materials
Authors: Moir David B , Beaulieu Normand , Curran Norman M , Lovering Edward G
Published: February 2020

A liquid chromatographic (LC) method for determination of naproxen and 8 known related compounds has been developed. The lower limit of quantitation of the related compounds In the drug Is 0.04% or less for all compounds; the precision of the drug assay method Is ca 0.4%. The method uses an octadecylsllyl column, a mobile phase of 1 % acetic acid (v/v)-methanol-acetonitrlle (48 + 22 + 30, v/v/v) and detection at 231 nm.
Analysis of Illegally Distributed Anabolic Steroid Products by Liquid Chromatography with Identity Confirmation by Mass Spectrometry or Infrared Spectrophotometry
Authors: Walters Milda J , Ayers, Russell J , Brown Daniel J
Published: February 2020

Anabolic steroid products found in the Illegal market are primarily oil-based Injectables or tablets and often do not contain the Ingredients declared on the label. An analytical scheme based on a reverse-phase liquid chromatographic (LC) system for screening, tentative Identification, and quantitation Is presented. Methanolic sample extracts are chromatographed on an octadecyl column using 2 mobile phases (methanol and (75+25) methanol-water) and tracked at 3 wavelengths (240, 210, and 280 nm) or with a photodlode array UV detector. Retention time ratios (RR) relative to testosterone and UV data are used for tentative Identification. The same LC system serves as a cleanup and Isolation step for Identity confirmation by direct Insertion probe mass spectrometry (MS) or Fourier transform Infrared spectrophotometry (FTIR). Recoveries range from 96.2 to 100.2% for 11 different steroids extracted from sesame oil. LC RR values for over 40 steroids, analytical results for typical products, and MS and FTIR spectra for selected compounds are presented.
Quantitative Analysis of Methionine, Cysteine, and Lysine in Feeds by Reversephase Liquid Chromatography Using Precolumn Derivatization with 9- Fluorenylmethyl Chloroformate: Preliminary Study
Authors: Fernández-Trapiella Angel Cubedo
Published: February 2020

An Improved analytical method based on precolumn derivatization with 9-fluorenylmethyl chloroformate (9-FMC) and reverse- phase liquid chromatography was developed for quantitative analysis of methionine, cysteine, and lysine In feeds. Samples of corn, whey powder, soybean meal, meat meal, and fish meal were selected for an accurate determination of these 3 amino acids. A portion of each finely ground sample was weighed and subjected to oxidation with performic acid for 16 h before hydrolysis with 6N HCI for 24 h. An aliquot of each hydrolysate was evaporated, dissolved, and diluted with 0.2M pH 7.85 borate buffer. An aliquot of each final solution was derlvatlzed with 9-FMC and analyzed by reverse- phase liquid chromatography using a fluorescence detector with a 254 nm excitation filter and a 313 nm emission filter. The 2 sulfur amino acids and lysine were perfectly separated from all other amino acids with a simple binary gradient. Cysteine (analyzed as cysteic acid), methionine (as methionine sulfone), and lysine were quantltated using internal standard calibration. Hydrolysates were also analyzed by conventional Ion-exchange chromatography (IEC). Amino acid values as obtained by the proposed LC method were close to IEC data. Considering IEC results as reference values, the differences In recovery of amino acids In feedstuffs determined by both methods were not more than 7.5%. Precision of the LC method was evaluated within a single hydrolysate and between different hydrolysates of a single sample. Coefficients of variation (CV) were not more than 4.1 and 5.9%, respectively.
Gas Chromatographic-Chemiluminescence Method for Determination of Volatile NNitrosamines in Minced Fish-Meat and Surimi-Meat Frankfurters: Collaborative Study
Authors: Pensabene John W , Fiddler Walter , Phillips John G
Published: February 2020

A collaborative study was carried out on a solid-phase extraction method for separating volatile N-nltrosamlnes, particularly N-nltrosodlmethylamlne (NDMA), from combination minced fish or surlml-meat frankfurters with detection by gas chromatography-chemllumlnescence (thermal energy analyzer). The results from the 10 collaborators were evaluated using the most recent AOAC guidelines for determining outliers and for the analysis of variance. For NDMA, repeatability standard deviations, sr, ranged from 0.56 to 2.25; repeatability relative standard deviations, RSDr, ranged from 8.9 to 11.5%. Reproducibility standard deviations, sR, for NDMA ranged from 1.40 to 6.49, and reproducibility relative standard deviations, RSDR, ranged from 24.2 to 28.9%. Our data compared favorably to the reproducibility (RSDR) curve of Horwltz. The method has been adopted official first action by AOAC.
A Displacement Pump Procedure to Load Extracts for Automated Gel Permeation Chromatography
Authors: Daft James , Hopper Marvin , Hensley Darrell , Sisk Ronald
Published: February 2020

Automated gel permeation chromatography (GPC) effectively separates lipids from pesticides In sample extracts that contain fat. Using a large syringe to load sample extracts manually onto GPC models having 5 mL holding loops is awkward, slow, and potentially hazardous. Loading with a small-volume displacement pump, however, Is convenient and fast (ca 1 loop every 20 s). And more Importantly, the analyst is not exposed to toxic organic vapors because the loading pump and Its connecting lines do not leak in the way that a syringe does.
Sulfuric Acid/Hydrogen Peroxide Digestion and Colorimetric Determination of Phosphorus in Meat and Meat Products: Collaborative Study
Authors: Christians David K , Aspelund Thomas G , Brayton Scott V , Roberts Larry L
Published: February 2020

Seven laboratories participated In a collaborative study of a method for determination of phosphorus in meat and meat products. Samples are digested In sulfuric acid and hydrogen peroxide; digestion Is complete In approximately 10 mln. Phosphorus Is determined by colorimetric analysis of a dilute aliquot of the sample digest. The collaborators analyzed 3 sets of blind duplicate samples from each of 6 classes of meat (U.S. Department of Agriculture classifications): smoked ham, water-added ham, canned ham, pork sausage, cooked sausage, and hamburger. The calibration curve was linear over the range of standard solutions prepared (phosphorus levels from 0.05 to 1.00%); levels in the collaborative study samples ranged from 0.10 to 0.30%. Standard deviations for repeatability (sr) and reproducibility (sR) ranged from 0.004 to 0.012 and 0.007 to 0.014, respectively. Corresponding relative standard deviations (RSDr and RSDR, respectively) ranged from 1.70 to 7.28% and 3.50 to 9.87%. Six laboratories analyzed samples by both the proposed method and AOAC method 24.016 (14th Ed.). One laboratory reported results by the proposed method only. Statistical evaluations Indicated no significant difference between the 2 methods. The method has been adopted official first action by AOAC.
Immunoassay of Pesticides
Authors: Kaufman Bennett M , Clower Marion
Published: February 2020

Determination of the presence and levels of pesticide residues In food Is fundamental In monitoring and regulatory programs. Residues are separated from the food matrix by solvent extraction, followed by cleanup steps. The residues are most often Identified and quantltated by instrumental analysis, usually liquid or gas chromatography. Extraction and cleanup are often laborious and time-consuming; determination requires expensive, sophisticated Instrumentation. There is a need for rapid, easily performed tests, such as Immunoassays, that could be used for screening under field conditions or for quantitation of residues In foods in the laboratory. Although a large number of immunoassays have been developed for pesticide chemicals, very few have been specifically applied to foods, and only a very small number are currently available commercially. The agencies charged with monitoring and regulatory responsibilities—Environmental Protection Agency, Food and Drug Administration, and U.S. Department of Agriculture—as well as professional societies such as AOAC and the International Union of Pure and Applied Chemistry, are Investigating and developing guidelines for test kit evaluation and standards to be met before a kit can be accepted as a practical and useful method of analysis for use In their programs.
Enzyme Immunoassay for Determination of Gluten in Foods: Collaborative Study
Authors: Skerritt John H , Hill Amanda S
Published: February 2020

A collaborative study was performed In 15 laboratories to validate a monoclonal antibody-based enzyme Immunoassay (EIA) for determination of gluten in foods. The study Included 13 samples: maize starch, "gluten-free" baking mixes, wheat flours, cookies, cooked meats, and a soup. Gluten was present In these samples at either zero or 0.02 to 10% by weight, I.e., over almost 3 orders of magnitude. The mean assay values for the foods varied from 88 to 105% of the actual amounts. The assay was quantitative for cereal products and the soup with repeatability (RSDr, relative standard deviation) and reproducibility (RSDR) of 16-22% and 24-33%, respectively. The assay was semiquantitative for the processed meat products (RSDr 14 and 26% and RSDr 46 and 56%), probably because gluten was unevenly distributed In the small (1 g) samples that were analyzed. The ELISA method produced no false positive results, and false negatives obtained with tannin-containing foods could be avoided by use of a modified sample extractant. None of the collaborators reported problems In following the protocol. The method has been adopted official first action by AOAC for determination of wheat gluten in foods.
Direct and Indirect Determination of True Protein Content of Milk by Kjeldahl Analysis: Collaborative Study
Authors: Barbano David M , Lynch Joanna M , Fleming J Richard
Published: February 2020

Currently, the reference procedure for determination of the "protein" content of milk is based on measurement of the total nitrogen content of milk by the Kjeldahl method (AOAC method, 920.105). About 6% of the total nitrogen content of milk Is nonprotein nitrogen. Therefore, total nitrogen multiplied by the conversion factor 6.38 overestimates the true protein content of milk on average by about 6%. In the present study, new direct and Indirect methods were developed for measurement of the true protein content of whole milk by Kjeldahl nitrogen determination. Both new methods are sample preparation procedures used to fractionate the nitrogen-containing compounds In milk prior to measurement of the nitrogen content of these fractions by Kjeldahl analysis. The collaborative study consisted of 9 pairs of blind duplicate milk samples that were analyzed for total nitrogen, nonprotein nitrogen, and protein nitrogen by each of 10 laboratories. Both methods for true protein measurement (direct and Indirect) gave acceptable statistical performance characteristics and good agreement between methods. The new direct method requires about half the laboratory analysis work of the indirect method (i.e., total minus nonprotein nitrogen). The methods have been adopted official first action by AOAC as (1) a new method for nonprotein nitrogen determination in milk, (2) a new method (direct) for determination of protein nitrogen content of milk, and {3) an alternative method (indirect) for determination of protein nitrogen content of milk.
Matrix Solid Phase Dispersion (MSPD) Isolation and Liquid Chromatographic Determination of Furazolidone in Pork Muscle Tissue
Authors: Long Austin R , Hsieh Lily C , Malbrough Marsha S , Short Charles R , Barker Steven A
Published: February 2020

A method for the Isolation and liquid chromatographic (LC) determination of furazolidone In pork muscle tissue is presented. Blank or furazolldone-forllfled pork muscle tissue samples (0.5 g) were blended with octadecylsllyl (C18,18% load, endcapped, 2 g) derlvatlzed silica. A column made from C18/pork matrix was first washed with hexane (8 mL), followed by elution of furazolidone with ethyl acetate. The ethyl acetate extract was then passed through an activated alumina column. The eluate contained furazolidone that was free from Interfering compounds when analyzed by LC with UV detection (photodlode array, 365 nm). Detector response with Increasing concentrations of furazolidone Isolated from fortified samples was linear (r = 0.998 ± 0.002) with an average percentage recovery of 89.5 ± 8.1% for the concentration range (7.8-250 ng/g) examined and resulted in a minimum detectable limit of 390 pg on column, and a detector response of more than 5 times baseline noise. The interassay variability was 9.9 ± 5.4% with an Intra-assay variability of 1.5%.
Liquid Chromatographic Determination of Glyphosate and Aminomethylphosphonic Acid (AMPA) in Environmental Water: Collaborative Study
Authors: Oppenhuizen Mark E , Cowell John E
Published: February 2020

A new method for determination of glyphosate and amlnomethylphosphonlc acid (AMPA) residues In environmental water was collaboratively studied by 6 laboratories. The method Is simpler and shorter than previous methods. A filtered volume of water is evaporated to dryness and the residue Is dissolved In a buffered EDTA solution. Glyphosate and AMPA are determined by liquid chromatography with postcolumn reaction detection. The method was validated over the range 0.50-5000 ppb, although one of the collaborating laboratories could not reliably quantltate below 1.0 ppb. Statistical analysis of the results showed that typical reproducibility relative standard deviations (RSDR) ranged from 11 to 20% for both glyphosate and AMPA, which compares very well with predicted values for this concentration range. Total variability (as measured by sR) Increased with increasing fortification level. The method has been adopted official first action by AOAC.
Development and Validation of a Method for Determining Elements in Solid Waste Using Microwave Digestion
Authors: Binstock David A , Grohse Peter M , Gaskill Alvia , Sellers Charles , Kingston H M , Jassie Lois B
Published: February 2020

A microwave-assisted method for preparing samples for determination of elements In solid waste has been developed (draft EPA Method 3051). Validation of the sample preparation method was performed through a collaborative study to determine its precision and accuracy. Fifteen independent laboratories digested 4 National Institute of Standards and Technology (NIST) standard reference materials (SRMs) and 1 solvent recovery waste in duplicate. Digestates were analyzed for 19 elements using inductively coupled plasma (ICP) emission spectroscopy. The precision and bias of the method were evaluated. When compared with an open vessel hot-plate digestion method (SW-846 Method 3050), the microwave method produced similar analytical results with better overall precision. Bias for the 1 sample that allowed this determination was found to be excellent.
Methods for Assay, Related Substances, and Organic Volatile Impurities in Triazolam Raw Materials and Formulations
Authors: Beaulieu Normand , Cyr Terry D , Graham Susan J , Lawrence Robert C , Sears Roger W , Lovering Edward G
Published: February 2020

Liquid chromatographic methods have been developed for determination of triazolam and related compounds in drug raw materials and tablets. The methods resolve 9 available related compounds from the drug with quantitation limits of 0.1 % or less. Eight raw materials and 16 formulations were examined for related compounds. Total impurities in raw materials ranged up to 0.6% and up to 1% in formulations, not including a compound in some tablets that is believed to be excipient related. Assay values were between 99.9 and 101.3% for raw materials and between 89.4 and 105.5% for tablets. A gas chromatographic method was developed for organic volatile Impurities in drug raw materials. The major solvents found were methyl ethyl ketone (100-750 ppm), ethyl acetate (510 ppm), and n-propanol (80-300 ppm), with a trace of benzene (<30 ppm) in several samples.
New Microbiological Method for Determining Spectinomycin in Pelleted and Meal Feeds Using Trifluoroacetic Acid as Primary Extractant
Authors: Stahl Gerald L , Zaya Matthew J , Paulissen Jerome B
Published: February 2020

A new microbiological method, Identified as the spectinomycin trifluoroacetic (SPE-TFA) method, was compared with the current AOAC method for analyzing spectinomycin in meal and pelleted feeds fortified with LS-20™ premlx. Feeds containing 3 concentrations of drugs and a zero level were tested in a correlation study. The data showed no significant differences in the percent of theory assayed between meal and pelleted samples using the SPE-TFA method, but the percent of theory found using the AOAC method was significantly lower for the pelleted samples than for the meal samples. The within-sample variation of the AOAC assay was also not the same for all samples; the SPE-TFA assay variation was relatively constant for all samples. The SPETFA method produced an overall average recovery of 98% with a range of 89-109% compared with an 85% recovery ranging from 64 to 102% for the AOAC method. In addition to producing better recoveries, the SPE-TFA method features a more sensitive response line, and final test solutions have viscosities and clarity more comparable to the standard solutions than those produced by the current AOAC method
Determination of Food Contamination by Mineral Oil from Jute Sacks Using Coupled LC-GC
Authors: Grob Konrad , Lanfranchi Mauro , Egli Jnes , Artho Anna
Published: February 2020

Jute fibers are treated with about 5-7% of a high boiling mineral oil fraction ("batching oil") to render them flexible for making fabrics. Foods transported in jute bags are contaminated by this batching oil. A method involving automated on-line LC-GC is described for determining these hydrocarbons in various foods. Complete transfer of the LC fraction to GC is presupposed for obtaining the required sensitivity. Results are given for nuts, coffee, cocoa products, and rice. Contamination ranged between about 5 and 500 ppm.
Continuous Flow Vapor Generation for Inductively Coupled Argon Plasma Spectrometric Analysis. Part 2. Arsenic
Authors: Tracy Mark L , Littlefield Sue E , Möller Gregory
Published: February 2020

Total arsenic Is determined by Inductively coupled plasma atomic emission using hydride vapor generation. A 1 g sample is wet ashed in a 16 X 150 mm 10 mL volumetric test tube on a programmed heating block with nitric, sulfuric, and perchloric acids at up to 310 °C. After treatment with hydrochloric acid and potassium iodide, arsenic Is reduced by sodium borohydride to arsine In a simplified continuous flow manifold. A standard pneumatic nebulizer effects the gasliquid separation of AsH3, which is quantified by ICP atomic emission at 193.756 nm. The instrument detection limit for the method has been determined to be 0.4 μg/L. For a 10:1 dilution of a nominal 1 g sample, the detection limit is 4 μg/kg and the linear range Is up to 4 mg/kg. Recoveries from 3 matrixes were 99-104%, with a typical RSD of 2%. The method has demonstrated statistical control for samples of biological interest and is especially well suited to analysis of small samples.
A Resuscitation/Selection System for Rapid Determination of Salmonella in Foods
Authors: Martin Alain , Katz Stanley E
Published: February 2020

A resuscitation medium was developed consisting of a trypticase soy broth base supplemented with 0.5% yeast extract, 0.25% sodium pyruvate, 0.01% sodium thioglycollate, and 0.1% chicken fat. After a resuscitation period of 4 h, the medium was made selective by addition of either sodium thiosulfate, bile salts and iodine, or sodium selenite and Lcystine. The now selective medium was incubated for 16 h. The presence or absence of Salmonella was determined by the Salmonella-Tek antibody-based detection kit. The present system was compared with a method of the Bacteriological Analytical Manual(BAM) for naturally contaminated foods. Nineteen egg products were screened; 3/19 were positive using the BAM method, 9/19 were positive using the present system. Seventeen chicken samples were assayed; 10/17 were positive using the BAM method; 13/17 were positive using the present system. Of 8 pepper samples, 4/8 were positive using the BAM method; 6/8 were positive using the present system. Of 8 spice samples, 6/8 were positive using the BAM method, 7/8 were positive using the present system. Of 6 onion products sampled, 5/6 were positive using the BAM method; 6/6 were positive using the present system.
Liquid Chromatographic Determination of the Processing Aid 4-Hexylresorcinol in Shrimp
Authors: King Joan M , McEvily Arthur J , Iyengar Radha
Published: February 2020

A rapid, sensitive, liquid chromatographic (LC) method has been developed for determination of residuals of the processing aid, 4-hexylresorcinol, on shrimp meat. An aqueous homogenate of shrimp meat is extracted with ethyl acetate followed by precolumn preparation on a silica Sep-Pak cartridge. LC determination is preformed with a Nova-Pak C18 column, with UV detection at 214 nm. Sensitivity was 0.006 μg, and recovery from shrimp meat samples of known 4-hexylresorcinol addition was 94%. Shrimp treated with 4-hexylresorcinol under the recommended dip protocol had mean residuals of 1.18 ppm, with a standard deviation of 0.13 ppm.
Assay of Oxolinic Acid Residues in Salmon Muscle by Liquid Chromatography with Fluorescence Detection: Interlaboratory Study
Authors: Carignan Germain , Larocque Lyse , Stephen Sved ,   Collaborators:, Carrier K , Ikai Y , Reimer G , Schermerhorn P G , Zitko V
Published: February 2020

A previously developed method that uses a simplified sample preparation and fluorometric detection of liquid chromatographic eluates for the determination of oxolinic acid in salmon muscle has been collaboratively studied. Five laboratories participated in the study to analyze, in quintuplicate, blank salmon muscle fortified at 10, 20, 50, and 100 μg/kg (ppb), and 2 incurred samples from salmon given feed with medicated oxolinic acid. The tissue, 2 g mixed with 2 g Na2S04, is extracted with ethyl acetate and centrifuged, and the solvent Is evaporated. The residue is partitioned in a mixture of hexane and 0.01 M oxalic acid, and the aqueous phase is chromatographed using fluorescence detection at 327 nm excitation and 369 nm emission. Mean recoveries ranged from 77.2 to 84.5% in spiked samples with reproducibility relative standard deviation (RSDR) ranging from 11.5 to 18.3%. Treated salmon were found to contain 8.71 and 53.8 μg/kg with RSDR of 18.6 and 16.7%, respectively. The corresponding repeatability relative standard deviations (RSDr) were 5.8-12.2%, and 7.7 and 6.2%. The method is recommended for regulatory purposes in Canada.
A New Approach to the Study of Glucosinolates by Isocratic Liquid Chromatography. Part I. Rapid Determination of Desulfated Derivatives of Rapeseed Glucosinolates
Authors: Quinsac Alain , Ribaillier Daniel , Elfakir Claire , Lafosse Michel , Dreux Michel
Published: February 2020

Liquid chromatographic (LC) analysis of desulfated derivatives of rapeseed glucosinolates has been carried out under isocratic elution conditions with different CN-bonded stationary phases. The effects of the eluant composition (water, acetonitrile, and methanol) with the stationary phase (Zorbax CN, Lichrospher CN, and Ultrasphere CN) and temperature (20 and 50°C) are described. An isocratic LC method performed at room temperature using a Lichrospher CN column and water as mobile phase is proposed. The chromatographic analysis can be done in less than 12 min, and it is easier and less expensive than the traditional gradient mode. Four commercial samples of rapeseed containing various quantities of other cruciferous seeds (wild mustard and stinkweed) as an admixture have been analyzed to determine the total giucosinolate content. Relative standard deviations of repeatability of the isocratic and gradient LC methods ranged from 0.4 to 1.7% and from 2.7 to 4.7%, respectively. Comparison of the results showed good agreement between the 2 methods (better than 98%).
Development of a Deer Rapid Identification Field Test (DRIFT) by Modified Agar-Gel Immunodiffusion
Authors: Cutrufelli Mark E , Mageau Richard R , Schwab Bernard , Johnston Ralph W
Published: February 2020

A deer rapid identification field test (DRIFT) has been developed for detection of deer meat (venison) In a wide variety of meat products. The test is an adaptation of previously developed field screening immunodiffusion tests for detection of other individual species. DRIFT was demonstrated to be specific, sensitive, and accurate in the analysis of 100 samples. This test Is especially well suited for use by state officials in charge of game regulations.
Liquid Chromatographic Determination of Flurazepam
Hydrochloride in Bulk Drug and Dosage Forms:
Collaborative Study
Authors: Bargo Eileen S
Published: February 2020

Eleven laboratories collaboratively studied the liquid chromatographic method for determining flurazepam hydrochloride In capsules and bulk drug. The method uses an octadecylsllane reversed- phase column, a mobile phase of methanol- 1% ammonium acetate (80 + 20), and photometric detection at 239 nm. Each collaborator received 8 samples: powdered composites of 5 commercial capsule preparations, each as a blind duplicate pair, and 3 bulk drug samples (1 blind duplicate). The ranges of repeatability and reproducibility relative standard deviations were 0.93-2.46 and 2.42-3.86% for the capsule samples and 0.97 and 1.76-2.27% for the bulk drug samples, respectively. The method was adopted first action by AOAC International.
Graphite Furnace Atomic Absorption Method for the Determination of Chromium in Foods and Biological Materials
Authors: Ihli N J . Miller , Greene F E
Published: February 2020

A method was developed for the determination of chromium in food samples and other biological materials. Samples are dry ashed In a muffle furnace and are analyzed by graphite furnace atomic absorption spectrometry. Magnesium nitrate is used as a matrix modifier, and samples are quantltated by platform atomizatlon and peak area measurements with direct calibration against aqueous standards. The detection limit (based on 3.29 σ) was 5.6 pg, or 0.28 μg/L for a 20 μL injection. The characteristic mass was 3.2 pg. This method was validated by analyzing a range of reference materials and was subsequently used for the analysis of a variety of food samples. A comparison of analytical results obtained from direct calibration and method of additions was made.
Interlaboratory Study of Decreasing the Number of Standard Points in the Official Iron Standard Curve
Authors: Martin James I , Soliman A M
Published: February 2020

An Interlaboratory study was conducted to (1) evaluate the effects of reducing the 10 points for the iron standard curve to 5 points in Official Methods of Analysis (1990) 15th Ed., sees 944.02A-944.02C(a), and (2) compare the levels of Iron found In foods by using the 10-point and 5-point standard curves. The 5 points (0.2, 0.6, 1.0, 1.4, and 1.8 μg Fe/mL) were selected by eliminating every other standard point from the 10-point curve after correction for the reagent blank. No differences in the performance parameters between method versions were found when blind duplicate analysis was used to estimate the performance parameters for each sample analyzed.