bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulatory Approach to Determination of Lysine in Feedstuffs by Liquid Chromatography with Fluorescence Detection via Precolumn Dansylation
Authors: Thio Alan , Tompkins David H 
Published: February 2020

Abstract
A method for compliance analysis for total lysine in animal feed is described. One g portions of finely ground feed sample are spiked with a calculated amount of diaminobutyric acid internal standard and hydrolyzed by heating with 100 mL 6N aqueous HC1 at 120°C in a closed bottle. A very small aliquot (25 /*L) of hexane-washed hydrolysate is evaporated under vacuum to dryness and derivatized with dansyl chloride. Lysine is separated from other amino acids by isocratic reverse-phase (LC-18) liquid chromatography; the mobile phase is acetonitrile-O.OlM sodium phosphate (pH 7.0) buffer (100 + 210, v/v). The internal standard method along with a fluorescence detector (310-410 nm excitation and 435-650 nm emission), is used for quantitation. Thirty-five feed samples of various types (lysine 0.2- 8.2%) were analyzed with no interference from the matrix. The results were compared with those furnished by an independent laboratory using an amino acid analyzer; no statistical difference was found at the 95% confidence level. Six replicate analyses of a feed sample showed a coefficient of variation of 2.8%; no significant differences were found when between-day results of 9 samples (lysine 0.90- 4.30%) were compared. This procedure has been tested for ruggedness and can be applied for compliance determination of total lysine in feedstuffs by laboratories with limited resources
Evaluation of Various Methods for Measurement of Pectin Content in Jam
Authors: Carbonell Elvira , Costell Elvira , Durán Luís 
Published: February 2020

Abstract
Suitability, precision, and accuracy of 3 colorimetric methods to measure pectin content in fruit jams are examined. The methods resolve non-uronide interferences in different ways: (1) with 3,5-dimethylphenol colorimetric reagent, and absorbance differences measured at 450 and 400 nm; (2) with m-hydroxydiphenyl colorimetric reagent, and numeric correction of sample blank to compensate for interferences; and (3) with m-hydroxydiphenyl colorimetric reagent and removal of interferences by purification of sample pectins. The 3,5-dimethylphenol method is not suitable when fructose is present. Precision and accuracy of the second method are not satisfactory because sugar/pectin ratio in jam samples is very high. The third method is recommended because the precision (0.9% &lt; CV &lt; 6.4%) is good and recovery is nearly 100%.
Multiresidue Method for Isolation and Liquid Chromatographic Determination of Seven Benzimidazole Anthelmintics in Milk
Authors: Long Austin R , Hsieh Lily C , Malbrough Marsha S , Short Charles R , Barker Steven A 
Published: February 2020

Abstract
A multiresidue method for the isolation and liquid chromatographic determination of 7 benzimidazole anthelmintics (thiabendazole, oxfendazole, para-hydroxyfenbendazole, fenbendazole sulfone, mebendazole, albendazole, and fenbendazole) in milk is presented. Blank or benzimidazole-spiked milk samples (0.5 mL) were blended with octadecylsilyl (C-18, 18% load, end-capped) derivatized silica packing material. A column made from the C-18/milk matrix was first washed with hexane (8 mL), and then the benzimidazoles were eluted with methylene chloride-ethyl acetate (1 + 2, v/v; 8 mL). The eluate contained benzimidazole analytes which were free from interfering compounds as determined by UV detection (photodiode array, 290 nm). Correlation coefficients of standard curves for individual benzimidazoles isolated from spiked samples were linear (0.989 ± 0.003 to 0.998 ± 0.001) with recoveries ranging from 70 ± 9% to 107 ± 2% for the concentration range (62.5-2000 ng/mL) examined. The inter- assay variabilities ranged from 4 ± 1% to 9 ± 7% with intra-assay variabilities of 3-6%.
Optimized Gel Permeation Chromatographic Cleanup for Soil, Sediment, Wastes, and Oily Waste Extracts for Determination of Semivolatile Organic Pollutants and PCBs
Authors: Czuczwa Jean M , Stevens Ann Alford 
Published: February 2020

Abstract
A gel permeation chromatographic (GPC) method, used by the U.S. Environmental Protection Agency (USEPA), was modified for cleanup of soil, sediments, wastes, and oily wastes before determination of semivolatile organic pollutants. The modifications included new calibration procedures and control of the amount of material processed. The modifications were evaluated for soil and sediment matrixes in a 5-laboratory study where each laboratory processed a solution containing a phthalate, substituted phenols and benzenes, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), nitroaniline, and pesticides. With the exception of nitroaniline, analyte recoveries were 87-112%, with relative standard deviations (RSDs) of 6.7-26%. Soil samples containing PCBs and fortified with 6 pesticides at 0.7-4 /ig/g were also analyzed by the 5 laboratories. The mean recovery of the 6 pesticides was 100% with a mean RSD of 16%. Mean RSD for the determination of total PCBs was 8.9%. An additional modification for the processing of wastes and high concentration waste samples was attempted; this involved GPC processing of sample extracts dissolved in 1 + 1 butyl chloridemethylene chloride. This modification did not improve recoveries of the semivolatile analytes. Finally, the modified GPC protocol was applied to PCB-contaminated reclaimed waste oils samples. Two GPC cleanup steps were used to separate PCBs from the waste oil samples before PCBs were determined by gas chromatography combined with electron-capture detection (GC/ECD).
Determination of Organic Acids in the Presence of Metal Ion
Authors: Koseki Masamichi , Takahashi Iwao , Yasuno Tetsuko , Ogino Shuzo , Tsuda Yuko , Kazama Masayoshi 
Published: February 2020

Abstract
The recovery of organic acids: citric, tartaric, fumaric, succinic, and malic, was examined by liquid chromatography in the presence of calcium, magnesium, or aluminum ions. Calcium and magnesium ions, i.e., ions of valence +2, did not interfere in determinations of the organic acids examined here. These organic acids could be determined without interference from aluminum ion by pH adjustment of the solutions to pH 2.
Comparison of Volatile Acid Number Test with Enzymatic Acetic Acid Assay for Assessment of Seafood Quality
Authors: Mccarthy Helen T , Ellis Christopher P , Silva Mary Lou , Mills Barbara 
Published: February 2020

Abstract
Volatile acid number, an official AOAC method for assessing seafood quality, was compared with an enzymatic method for measuring acetic acid. Thirty-eight samples of fresh fish and 23 samples of canned fish were evaluated. The data showed high positive correlations between volatile acid number and enzymatic acetic acid methods; the correlation coefficient was 0.98 for fresh fish and 0.95 for canned fish. Positive correlation coefficients of 0.93 and 0.96 were also associated with samples of fish divided into 2 groups on the basis of acceptable or unacceptable quality, respectively. There was no significant difference between the means for the volatile acid number and enzymatic acetic acid procedures at the 5% level of significance. Decomposition studies on cod and mackerel, representing a lean and fatty fish, respectively, were monitored over 9 days by using the following analyses: volatile acid number, acetic acid, total volatile bases, and thiobarbituric acid. Results of the decomposition studies showed that enzymatic acetic acid levels closely paralleled volatile acid number values in both lean and fatty fish. Total volatile bases was a reliable supplemental measure for evaluating lean seafood quality, whereas thiobarbituric acid was more appropriate for further assessment of fatty fish quality.
Capillary Column Gas Chromatographic Determination of Dicamba in Water, Including Mass Spectrometric Confirmation
Authors: Jimenez Nancy C , Atallah Yousef H , Bade Thomas R 
Published: February 2020

Abstract
A sensitive method is described for determining dicamba at low μg/L levels in ground waters by capillary column gas chromatography with electron-capture detection (GC-EC); compound identity is confirmed by gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring. Dicamba residue is hydrolyzed in KOH to form the potassium salt. The sample is then extracted with ethyl ether which is discarded. The aqueous phase is acidified to pH &lt; 1 and extracted twice with ethyl ether. The combined ethyl ether extracts are concentrated, and the residue is methylated using diazomethane to form the corresponding dicamba ester. The derivatized sample is cleaned up on a deactivated silica gel column. The methylated dicamba is separated on an SE-30 capillary column and quantitated by electron-capture or mass spectrometric detection. Average recoveries (X ± SD) for ground water samples fortified with 0.40 μg/L of dicamba are 86 ±5% by GC-EC and 97 ± 7% by GC-MS detections. The EDL (estimated detection limit) for this method is 0.1 μg dicamba/L water (ppb).
Monitoring of Fertilizer Plant Effluents for Phosphorus, Sulfur, and Metals Using Inductively Coupled Plasma Emission Spectrometry
Authors: Ardis Jimmie D , Baker Alice M 
Published: February 2020

Abstract
At present, the U.S. Environmental Protection Agency (EPA) lists total P, F, and total suspended solids as effluent limitations for fertilizer manufacturing point source discharges. Other contaminants, including metals, may be added on a plant-by-plant permitting basis. EPA test method 200.7 lists 25 metals that may be determined by inductively coupled plasma (ICP) emission spectrometry as dissolved, suspended, or total elements in drinking and surface waters and domestic and industrial wastewaters. A method to measure a large number of these metals, as well as phosphorus and sulfur in fertilizer plant effluent water, by ICP spectrometry is described. The ICP spectrometer offers quick, sensitive, and accurate determinations for all species of phosphorus and sulfur. Total P can be determined regardless of the species present (lower oxides, ortho, poly, or organic), and sensitivity to phosphorus (0.08 /μg/mL) is greater than for most other methods. Sensitivity to sulfur (0.1 /μg/mL) also is greater than for most other methods and can be determined as total, sulfate, sulfide, or sulfite by controlling sample preparation. The present paper addresses only the measurement of total S because methodology has not been completed for other species.
Comparison of Traacs 800 Autoanalyzer with Official Methodology for Total and Available Phosphorus in Fertilizer
Authors: Kane Peter F , Orcutt Anne L , Huber Janet H 
Published: February 2020

Abstract
A third generation of continuous flow analyzers, the Traacs 800, as configured for total P2O5 in fertilizers, was compared to the traditional gravimetric methodology. A t-test of routine samples gave t = -1.01 with 23 DF, indicating no significant difference at the 95% confidence level. The average bias, gravimetric minus analyzer, was -0.03% P2O5. The instrument configured for available P2Os was also compared to second generation AAII instrumentation. Bias was shown to exist in both instruments, which could be overcome by use of matrix standards. When routine samples were extracted and compared on the 2 instruments using matrix standards, a t-test gave t = —1.54 with 26 DF, indicating no significant difference. The average bias, Traacs minus AAII, was -0.06% P2O5. Official AOAC method status will be pursued for both Traacs methodologies.
Gas Chromatographic Determination of Nicotine in Environmental Tobacco Smoke:
Collaborative Study
Authors: Ogden Michael W 
Published: February 2020

Abstract
A gas chromatographic method for determination of vapor phase nicotine in environmental tobacco smoke (ETS) was collaboratively studied by 6 laboratories. Nicotine is desorbed from XAD-4 sample tubes with ethyl acetate containing triethylamine and determined by gas chromatography with nitrogen-selective detection. Each collaborator received blind duplicate samples at each of 6 nicotine concentrations. Three concentrations were generated by spiking XAD-4 tubes with known amounts of nicotine; the remaining 3 concentrations were ETS samples obtained in a carefully controlled environmental chamber containing sidestream and exhaled mainstream smoke from 1R4F Kentucky reference cigarettes. Repeatability and reproducibility relative standard deviations ranged from 4.4 to 11.1% and from 7.0 to 11.1%, respectively, for nicotine concentrations evaluated (up to 6 ng/cu m). The method has been adopted official first action.
Ethyl Carbamate Levels in Selected Fermented Foods and Beverages
Authors: Canas Benamin J , Havery Donald C , Robinson Louis R , Sullivan Michael P , Joe frank L , Diachenko Gregory W 
Published: February 2020

Abstract
Ethyl carbamate (EC), also known as urethane, is an animal carcinogen and a by-product of fermentation. Because EC has been found in distilled spirits and wines, a variety of fermented foods and beverages were analyzed to assess its occurrence in other products. Previously described methods using a gas chromatograph-thermal energy analyzer with a nitrogen converter were modified for each matrix and gave recoveries of &gt;80%, with a limit of detection in the 1-2 μg/kg(ppb) range. A total of 152 test samples were analyzed; EC levels ranged from none found to 3 ppb in 15 cheeses, 6 teas, 12 yogurts, and 8 ciders; from none found to 13 ppb in 30 breads and 69 malt beverages; and from none found to 84 ppb in 12 soy sauces. Gas chromatography/mass spectrometry/mass spectrometry was used to confirm EC identity and to quantitate EC in selected food extracts
Rapid Colorimetric Determination of Activity of Subtilisin Enzymes in Cleaning Products
Authors: Klein Allan E , Freiberg John , Same Steven , Carroll Maryanne 
Published: February 2020

Abstract
A new colorimetric method is described for the determination of enzymatic activity of subtilisin in cleaning products. The procedure is more rapid and precise than the casein digestion methods commonly used to assay protease activity. The principle of the colorimetric method depends on the determination rate of p-nitrophenol released on hydrolysis of N-CBZ-L-leucine-/Miitrophenyl ester at pH 8.0 by subtilisin, with correction for any nonenzymatic (spontaneous) hydrolysis of the substrate. Because of the broad range of hydrolytic activity of this enzyme, and the difficulties in predicting its proteolytic activity, this hydrolytic rate was chosen as a general indicator of subtilisin enzyme behavior. The slope for 7 replicate standard curves generated over a 6 week period exhibited a relative standard deviation of 7.5%, and 8.0% for 20 replicates with an enzyme cleaning product. Papain does not interfere with this assay.
Precolumn Phenylisothiocyanate Derivatization and Liquid Chromatography of Amino Acids in Food
Authors: Hagen Steven R , Frost Beverly , Augustin Jorg 
Published: February 2020

Abstract
A precolumn phenylisothiocyanate derivatization method is described for the determination of amino acids in protein hydrolysates from a wide variety of complex food matrixes, with and without performic acid oxidation pretreatment. Analysis of samples that were not pretreated with performic acid was necessary since this pretreatment destroyed an average of 25% of the histidine and 87% of the tyrosine present in the food samples. This method is rapid and reproducible; coefficients of variation between duplicate analyses of the same food item were less than 5% for a majority of the amino acids. Occasionally, variation between duplicate analyses for histidine and tyrosine was greater than 10%. Recoveries of amino acids added to samples were in the 100% range.
Spectrophotometric Method for Microdetermination of Nitrogen in Kjeldahl Digest
Authors: Devani Muljibhai B , Shishoo Chamanlal J , Shah Shailesh A , Suhagia Bhanubhai  N 
Published: February 2020

Abstract
A new spectrophotometric method for the determination of nitrogen in Kjeldahl digest has been developed. The method is based on the reaction of ammonia with acetylacetone-formaldehyde reagent in aqueous medium to yield yellow 3,5-diacetyl- 1,4-dihydrolutidine with a characteristic absorption maxima at 412 nm. The effect of several experimental variables on the determination of nitrogen was studied. The method was suitable for determination of nitrogen in acidic medium without interference from the usual catalysts employed for the digestion in Kjeldahl method. Lambert-Beer’s law is obeyed in the concentration range of 0.5-6.0 ng nitrogen/mL in the reaction mixture. The molar absorptivity in terms of nitrogen was 1.4 X 103L mol-1 cm-1. The standard deviation and relative standard deviation were ±0.0447 and ±0.896% (n = 10), respectively. The method is simple, rapid, and precise. A variety of carbocyclic and heterocyclic nitrogen compounds have been analyzed for nitrogen content. The results are comparable with those obtained by AOAC method, 47.021.
Comparison of Two ELISA Screening Tests with Liquid Chromatography for Determination of Aflatoxins in Raw Peanuts
Authors: Dorner Joe W , Cole Richard J 
Published: February 2020

Abstract
A study was conducted to evaluate the performance of 2 enzymelinked immunosorbent assays (ELISA) for rapidly screening samples of peanuts for the presence of aflatoxin. The EZ-Screen Quick Card Test and the Afla-10 Cup Test were compared with liquid chromatography in duplicate analyses of common extracts of peanuts contaminated in the range of 0-70 ppb (ng/g). Each assay properly identified 95% of samples containing no detectable aflatoxin as negative and &gt;97% of samples containing &gt;10 ppb aflatoxin as positive. The card test, which had a 20 ppb detection threshold, identified as positive 32 of 34 samples in the 11-20 ppb range. This indicates that the card test might actually have a detection threshold closer to 10 ppb. Most of the errors associated with the assays occurred on samples containing &lt;10 ppb aflatoxin. The cup and card tests identified 76 and 67% of the samples, respectively, as negative, in the range of 4-10 ppb. For samples either negative or contaminated above their detection thresholds for the assays, the methods are well suited for use as rapid screening tests.
Monoclonal Antibody-Based Enzyme Linked Immunosorbent Assay of Aflatoxin B1, T-2 Toxin, and Ochratoxin A in Barley
Authors: Ramakrishna Nannapaneni , Lacey John , Candlish Alan A.G , Smith John E , Goodbrand Ian A 
Published: February 2020

Abstract
Aflatoxin B1 (B1), T-2 toxin (T2), and ochratoxin A (OA) were assayed in a single extract from barley grain by using competitive enzyme linked immunosorbent assays (ELISAs) with monoclonal antibodies. B1 and T2 monoclonal antibodies were conjugated to horseradish peroxidase for direct competitive ELISA while an indirect competitive ELISA was used for OA determination. The competitive ELISA detected 0.1 ng/mL of B1f 10 ng/mL of T2, or 1 ng/mL of OA. Acetonitrile- 0.5% KCI-6% H2S04 (89 + 10 + 1 ) extracts of barley grain either were diluted 1:10 for direct assay or were subjected to a simple liquid-liquid cleanup procedure to concentrate the extract 10:1 before assay. For cleanup, water was added to the acetonltrile extract to partition water-soluble interfering substances, and then the mycotoxins were re-extracted with chloroform. The chloroform extract was evaporated to dryness and redissolved in Tris HCI buffer for ELISA. The mean recoveries from barley spiked with 4-60 ng/g of B1( 50-5000 ng/g of T2, and 5-500 ng/g of OA were, respectively, 93.8, 80.6, and 95.8%. The mean within-assay, Inter-assay, and subsample coefficients of variation by ELISA of barley grain colonized with toxigenic fungi were &lt;12% for Bi and OA but as high as 17% forT2.
Diagnostic Data Evaluation. Part II. Collaborative Study Evaluation: Coefficient of Variation Considered To Be A Constant
Authors: Malanoski Anthony J 
Published: February 2020

Abstract
The principles described in Part I were used to determine standards of performance for the method and for analysts from a collaborative study of the determination of nitrosopyrrolidine (NPYR). Performance standards for the method were 10.4% RSDa, 9.2% for RSDo, and 14.2% for RSDx.
Polymeric Film Dialysis in Organic Solvent Media for Cleanup of Organic Contaminants
Authors: Huckins James N , Tubergen Mark W , Lebo Jon A , Gale Robert W , Schwartz Ted R 
Published: February 2020

Abstract
Dialytic enrichment, using a nonpolar polymeric film or membrane, is proposed as a new approach for the separation of organic contaminants from fish lipid. Nonpolar organochlorine analytes diffuse from the fish lipid through a polyethylene membrane into cyclopentane. Separations of 48 h or less in duration afforded excellent recoveries for all analytes tested and removed 93% of the fish oil. Kinetics of membrane diffusion and possible controlling factors are elucidated for selected analytes and model compounds. Potential advantages of this technique over conventional lipld-removal methods such as gel permeation chromatography include simplicity, large sample capacity, reduced solvent requirements, and amenability to interfacing in-line with other enrichment modules.
Extraction of Gasoline Constituents from Soil
Authors: Donaldson Susan G , Miller Glenn C , Miller W W 
Published: February 2020

Abstract
The recovery of gasoline constituents from soil by using a sonication/extraction method was evaluated. Ten characteristic compounds were studied: benzene, toluene, n-heptane, m-xylene, nonane, n-propylbenzene, 1,2,4-trimethylbenzene, n-butylbenzene, 1,2,4,5-tetramethylbenzene, and dodecane. Modifications of extraction method EPA 3550 were tested using flame ionization gas chromatography with a 15 m X 0.53 mm id fused-silica capillary column. For dry soils, reducing total solvent extraction volume from 400 to 250 mL resulted in equivalent recoveries and shorter analysis times. Recovery of the gasoline constituents from wet soils was significantly lower than from dry soils for all methods studied. Recoveries were also dependent on the relative constituent volatility. Higher molecular weight compounds were recovered at greater than 80% of the initial amount applied from dry soils; while recoveries of benzene and heptane were generally less than 5%. Using the most efficient extraction procedure, recovery of unleaded gasoline from a dry, spiked soil was 43.2% when expressed on a total petroleum hydrocarbon basis, and recovery from a wet, spiked soil was 21.8%.
Capillary Gas Chromatographic Method for Determination of Benzylpenicillin and Other Beta-Lactam Antibiotics in Milk
Authors: Meetschen Ute , Petz Michael 
Published: February 2020

Abstract
A capillary gas chromatographic method Is described for determining residues of beta-lactam antibiotic residues In milk, with specificity for benzylpenlclllln (penicillin G), phenoxymethylpenlcillin, methlclllln, oxacillin, cloxaclllln, dlcloxaclllln, and nafclllln. Residues are extracted from milk with acetonitrlle. Samples are cleaned up by partitioning between aqueous and organic phases at different pH values. The penicillin residues are methylated with dlazomethane to render them amenable to determination by gas chromatography on a methyl silicone fused silica column. Samples are introduced by spllt/splltless injection using a programmed temperature vaporization injector and are detected by nitrogenselective thermionic detection, internal standardization Is used for quantitation. The limits of detection for all penicillins are well below 1 /μg/kg. Recoveries of spiked samples at 3 and 10 μg/kg are in the range of 42-85% (coefficients of variation 2-5%) and 41-92% (coefficients of variation 3- 7%), respectively.