bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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.
Enzymatic-Spectrophotometric Method for Determination of Cholinesterase Activity in Whole Blood: Collaborative Study
Authors: Harlin Karen S , Ross P Frank 
Published: February 2020

Abstract
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 (&lt;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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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%.