bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enzyme-Linked Immunosorbent Assay of Aflatoxin Bi in Naturally Contaminated Corn and Cottonseed
Authors: Ram Bhanu P , Hart L Patrick , Shotwell Odette L , Pestka James J 
Published: February 2020

Abstract
Naturally contaminated corn and cottonseed samples were screened for aflatoxin B1 (AFB1) by a direct competitive enzyme-linked immunosorbent assay (ELISA). Samples were blended 5 min in an extraction solvent of methanol-water-dimethylformamide (70 + 29 + 1) and filtered. Filtrates were assayed by direct competition between AFBi in the corn and cottonseed samples and AFB1-peroxidase conjugate for binding to specific antibody adsorbed to a solid phase microtiter plate. Standard curves prepared using the extract of AFB1-free corn and cottonseed samples, and extraction solvent only, showed negligible interference by the sample extract in the performance of ELISA. The AFBi content in corn and dehulled cottonseed samples as determined by ELISA ranged from 7 to 422 μg/kg and 7 to 3258 μg/kg, respectively. When ELISA estimates of AFB1 in corn were compared with values obtained by thin layer chromatography (CB method), the correlation coefficient (n = 10) was 0.95. Average interassay and subsample coefficients of variation for ELISA in corn were 21.4 and 22.0%, respectively. When ELISA estimates of AFB1 in cottonseed were compared with values obtained by liquid chromatography (Pons method), the correlation coefficient (n = 15) was 0.96. Using this ELISA, 36 duplicate sample extracts can be screened for AFB1 in less than 2 h.
Gas Chromatography of Uracil Herbicides by On-Column Methylation with Trimethylanilinium Hydroxide
Authors: Ogierman Leonard 
Published: February 2020

Abstract
Substituted uracil herbicides injected into a gas chromatograph react with trimethylanilinium hydroxide to give iV-methyl derivatives with good gas chromatographic properties. Maximum methylation is obtained when the molar ratio of methylating reagent to herbicide is ca 4:1. This technique for preparing derivatives provides rapid qualitative and quantitative chromatography of the substances examined. Chromatographic response was linear with increased concentration for the synthetic standard and the on-column product of uracil herbicide. The proposed derivatization method was used to analyze herbicides in formulations. The methyl derivatives were identified spectroscopically
Current Trends in Levels of Volatile N-Nitrosamines in Fried Bacon and Fried-Out Bacon Fat
Authors: Canas Benjamin J , Havery Donald C , Joe Frank L , Fazio Thomas 
Published: February 2020

Abstract
Commercially processed bacon samples purchased from the Washington, DC, retail market have been periodically analyzed since 1971 for the presence of volatile A'-nitrosamines in the fried product. During that time, a downward trend in the concentration of N-nitrosopyrrolidine has been observed, and between 1978 and 1980 it plateaued at 4 - 30 ppb, with an average of 11 ppb. A recent survey, however, indicates a change in this downward trend, with A'-nitrosopyrrolidine found at levels ranging from 1 to 65 ppb, average 21 ppb. Volatile N-nitrosamines were found at levels up to 110 ppb in the fried product and up to 85 ppb in the fried-out bacon fat.
Surrogate-Assisted Determination of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in Fish by Electron Capture Capillary Gas Chromatography
Authors: Niemann Richard A 
Published: February 2020

Abstract
Surrogate spiking the sample with 1000 parts per trillion (pptr) 1,3,7,8-tetrachlorodibenzo-p-dioxin (1378-TCDD) has doubled analytical throughput in determining toxic 2378-TCDD (analyte) at the low partper- trillion level in fish, using multicolumn high resolution liquid chromatographic cleanup before quantitation by capillary gas chromatography with electron capture detection. The 1378- and 2378-TCDD were recovered equally and were well separated by the capillary column so that the earlier-eluting surrogate did not interfere with the quantitation of levels of analyte many-fold lower. Matrix interference contributed &lt;1 % bias in surrogate quantitation. Using surrogate recovery to correct for analyte losses during analysis, accuracy averaged (n = 7) 105% in determining 18 or 45 pptr 2378-TCDD added to fish without detectable bioincurred analyte. Analyses of selected fish with bioincurred 2378-TCDD gave results comparable to earlier work where recovery correction required a second analysis of sample fortified with analyte. With surrogate fortification, repeatability of determination (n = 3 or 4) improved markedly to &lt;5% relative standard deviation at 37-46 pptr.
On-Line Trace Enrichment for Determination of Aldicarb Species in Water, Using Liquid Chromatography with Post-Column Derivatization
Authors: Chaput Daniel 
Published: February 2020

Abstract
Liquid chromatography combining on-line trace enrichment together with a very selective detection technique is used for the determination of aldicarb, aldicarb sulfoxide, and aldicarb sulfone. Sensitivity is increased by loading a 10 mL volume of ground water on a concentrator column installed in the loop position of a 6-port injection valve. Switching the valves allows the concentrated material to be backflushed onto the analytical column by a methanol-water gradient mobile phase. Separation is followed by post-column hydrolysis to yield methylamine, and formation of a fluorophore with o-phthalaldehyde and 2-mercaptoethanol prior to fluorescence detection. The process requires virtually no sample cleanup and provides good precision on recoveries from different matrixes. Minimum detection limit, defined as 5 times baseline noise, is less than 70 ng/L for the 3 compounds.
Detection of Pork and Lard as Adulterants in Beef and Mutton Mixtures
Authors: Saeed Talat , Abu-Dagga Faisal , Rahman Hani Abdul 
Published: February 2020

Abstract
Detection of pork and lard in different beef and mutton mixtures was investigated. The extracted fat was hydrolyzed and esterified to methyl esters of fatty acids, which were then analyzed on a fused silica capillary ' column coated with FFAP. Gas chromatographic analysis showed that 11,14-eicosadienoic acid (C20.2) can be used as an indicator for the presence of pork or lard in beef and mutton mixture. C20:2 is not detected in beef or mutton and is present in pork and lard. Overall composition of the fatty acids can be used for rough estimation of sample composition. Using this method, a detection limit of 1% pork in beef and mutton was reached.
On-Column Partition Cleanup of Fatty Extracts for Organophosphate Pesticide Residue Determination
Authors: Di Muccio Alfonso , Cicero Anna Maria , Camoni Ivano , Pontecorvo Damiano , Dommarco Roberto 
Published: February 2020

Abstract
A fast, single-step, and efficient partition between n-hexane and acetonitrile on ready-to-use, disposable mini-columns of Kieselghur-type material has been developed for the cleanup of fatty extracts for organophosphate (OP) pesticide residue determination by gas chromatography with flame photometric detection. Nine OP pesticides (diazinon, etrimfos, chlorpyrifos-methyl, pyrimiphos-methyl, chlorpyrifos, bromophos, bromophos-ethyl, malathion, fenitrothion) most commonly used for protection of stored cereals, oil seeds, and legumes were separated from up to 2.0 g lipidic material with recoveries between 80 and 107% at spiking levels ranging for the different compounds from 0.1 to 5.0 ppm.
Automated Sample Cleanup for Pesticide Multiresidue Analysis. III. Evaluation of Complete System for Screening Subtolerance Residues in Vegetables
Authors: Gretch Fred M , Rosen Joseph D 
Published: February 2020

Abstract
An automated continuous flow sample cleanup system intended for rapid screening of foods for pesticide residues in fresh and processed vegetables has been developed. Recovery and precision data for 8 pesticides in each of 3 crops are compared for the automated and manual procedures. Average recovery for samples fortified with pesticides between 0.026 and 0.277 ppm was 98% for the automated system and 92% for the manual procedure. Average coefficient of variation was 6.6% for the automated system and 4.2% for the manual procedure. In another evaluation, the automated system gave an average recovery of 95% for 12 pesticides commonly found in imported foods; the manual procedure gave an average recovery of 91%. Thus, the results obtained so far indicate that the automated system for sample cleanup gives results comparable to those obtained by manual procedures.
Cyclopiazonic Acid Production by Cultures of Aspergillus and Penicillium Species Isolated from Dried Beans, Corn Meal, Macaroni, and Pecans
Authors: Trucksess Mary W , Mislivec Philip B , Young Kathryn , Bruce Verneal R , Page Samuel W 
Published: February 2020

Abstract
Ninety-five isolates of Aspergillus and Penicillium species from selected dried foods were examined for their ability to produce cyclopiazonic acid (CPA). The isolates were grown in sterile synthetic liquid medium at 28°C for 8 days in the dark. The medium and mold mycelia were then extracted with chloroform. CPA was semiquantitative^ determined by thin layer chromatography through visual comparison with standards. The cultures of A. flavus were also examined for their ability to produce aflatoxin. One A. tamarii and all 13 P. urticae isolates produced CPA, whereas only 19 of the 31 (61%) A. flavus isolates produced CPA, and 6 (19%) A. flavus produced aflatoxin. All 13 P. urticae isolates also produced patulin and griseofulvin. CPA-producing A. flavus was found in all food types but not in all samples. CPA-producing P. urticae was found only in dried beans and macaroni.
Quantitative Analysis of Cystine, Methionine, Lysine, and Nine Other Amino Acids by a Single Oxidation-4 Hour Hydrolysis Method
Authors: Gehrke Charles W , Rexroad Paul R , Schisla Robert M , Absheer Joseph S , Zumwalt Robert W 
Published: February 2020

Abstract
The sulfur-containing amino acids cystine and methionine play important roles in animal, especially avian, nutrition. Because these ndror-containing amino acids are destroyed to varying extents by 6N HC1 hydrolysis, oxidation and hydrolysis of cystine to cysteic add and methionine to methionine sulfone have been widely used for determination of cystine and methionine. Lysine is considered the next limiting amino acid after the sulfur amino acids in poultry •ntrition; therefore, determination of the amino acid content of rations focuses first on these 3 amino acids. The objective of this investigation was to establish whether lysine and other amino acids could be accurately determined in proteinaceous materials which had mdergone performic acid oxidation. To perform this evaluation, lysine was determined in a variety of protein-containing materials both with and without performic acid oxidation. Performic acid oxidation followed by 6N HC1 hydrolysis at 145°C for 4 h allows accurate measurement of 3 amino acids especially important to poultry nutrition, cystine, methionine, and lysine, in a single preoxidized hydralysate; this method can be extended to another 9 protein amino adds.
Mass Spectrometric Evidence for Demethylated Homologs Occurring at Trace Levels in Trichothecene Standards
Authors: Visconti Angelo , Mirocha Chester J , Pawlosky Robert J 
Published: February 2020

Abstract
Compounds with molecular weights 14 a.m.u. lower than their corresponding parent compounds have been detected in trichothecene standards during gas chromatography-mass spectrometry analysis. The positive ion chemical ionization mass spectra indicated that these compounds were trichothecene homologs lacking a methyl group on the isovaleroxy substituent at the C-8 position. Demethylated derivatives have been found in the standards of T-2, HT-2, and T-2 triol prepared in our laboratory and those obtained from a commercial source.
Simplified Method for Determining Polychlorinated Biphenyls, Phthalates,and Hexachlorocyclohexanes in Air
Authors: Stein Vincent B , Amin Thakor A. , Narang Rajinder Singh 
Published: February 2020

Abstract
A simplified method for determining polychlorinated biphenyls (PCBs), phthalates, and benzene hexachlorides (BHCs) in air has been developed. Florisil is used as the adsorbent, and compounds are elated by liquid chromatography with 10% 2-propanol in hexane. PCBs are separated from phthalates plus BHCs on a cyanopropyl column with a gradient containing 10% 2-propanol in hexane and 100% hexane as the mobile phase. Two fractions are collected: one contains PCBs and the other contains phthalates plus BHCs, which ve then determined by gas chromatography using a 63Ni electroncapture detector and a DB-5-bonded, fused-silica capillary column.
Capillary Column Gas Chromatographic Determination of Ethyl Carbamate in Alcoholic Beverages with Confirmation by Gas Chromatography/Mass Spectrometry
Authors: Conacher Henry B.S. , Page B.Denis , Lau Benjamin P.Y. , Lawrence James F. , Bailey Ruth , Calway Patrick , Hanchay Jean-Pierre , Mori Brian 
Published: February 2020

Abstract
A method is described for determining ethyl carbamate at low \i%l kg levels in several types of alcoholic beverages by capillary column gas chromatography with Hall electrolytic conductivity detection and confirmation by mass spectrometry. Samples are diluted to obtain a uniform concentration of ethanol (ca 10%) then saturated with NaCl and extracted with methylene chloride. Extracts are evaporated to a small volume and injected in ethyl acetate solution for chromatographic analysis. The method was evaluated by 5 laboratories, 4 employing the Hall detector and one using mass spectrometric detection. Overall between-laboratory mean percent recoveries were: wine, 85.3 ± 21.0% coefficient of variation (CV) (spiking level 20- 45 μg/kg); sherry, 83.8 ± 16.1% CV (spiking level, 81-142 μg/kg);whiskey, 79.5 ± 13.9% CV (spiking level 127-190 Mg/kg); and brandy, 85.0 ± 12.5% CV (spiking level 297-446 μg/kg). Mass spectrometric results agreed well with the Hall results for all commodities. Detection limits were about 5 μg/kg for the Hall detector and about 0.5 μg/kg for mass spectrometric detection.
Lead, Cadmium, and Fluoride Levels in Market Milk and Infant Formulas in Canada
Authors: Dabeka Robert W. , Mckenzie Arthur D. 
Published: February 2020

Abstract
Lead, cadmium, and fluoride were determined in 68 samples of market milk and about 115 infant formulas. Mean and median levels (ranges) in ng/g found for cow milk were as follows: lead, 1.12, 1.19 (0.01-2.48); cadmium, 0.10, 0.039 (0.005-0.74); and fluoride, 41, 40 (7-86). In canned, ready-to-use formulas, lead, cadmium, and fluoride levels averaged 37.3,1.50, and 840 ng/g, respectively. In concentrated liquid formulas, the respective levels were 21, 3.54, and 600 ng/g. In powder formula concentrates, respective levels were 73.7, 6.78, and 1130 ng/g. On the basis of this study and literature data, lead levels in market milk exceeding 5 ng/g appeared to signify contamination of the milk either directly or via the cow. For formulas considered on an as-consumed basis, lead levels exceeding about 10-15 ng/g were attributed to contamination from either the can used to store the formula or the formula ingredients. Infant formulas in lead-free cans contained about 1.7 ng/g of lead on a ready-to-use basis. Milkbased formulas contained about 0.26 ng/g of cadmium on a readyto- use basis. Soy-based or milk-free formulas contained about 8-15 times more cadmium than did milk-based formulas. Canadian and U.S. ready-to-use formulas contained 900 and 230 ng/g fluoride, respectively, and this difference was attributed to the level of fluoride in the processing water used by the manufacturers.
Simple Liquid Chromatographic Method for Determination of Carotenoids in Alfalfa Products
Authors: Lauren Denis R , McNaughton Donald E , Agnew Michael P 
Published: February 2020

Abstract
A dichloromethane extraction system has been developed which is suitable for alfalfa carotenoids and is compatible with nonaqueous reverse phase liquid chromatographic (LC) analysis. Ground samples are extracted in the presence of antioxidant with dichloromethaneacetone (2 + 1). After an overnight soak, the mixture is saponified with 40% w/v potassium hydroxide in methanol and then is partitioned with 10% w/v aqueous sodium sulfate. An aliquot of the lower yellow organic phase is used for LC analysis after dilution (1 + 1) with acetonitrile. An isocratic 2 solvent system of ethyl acetateacetonitrile containing 0.1% n-decanol as mobile phase modifier is used for liquid chromatography with a high carbon loading non-endcapped ODS packing material. In comparisons with the existing AOAC method for carotenes and xanthophylls in dried plant materials and mixed feeds, the proposed method gave consistently higher results in a range of 7-28%, depending on the substrate. Possible causes for the differences were examined and include losses during partition and column chromatography with the AOAC method. Calculation methods and the choice of standard materials may also contribute to the difference in results.
CoUisionally Activated Decomposition Mass Spectrometry/Mass Spectrometry Determination of Organophosphorus Pesticide Residues in Foods
Authors: Roach John A G , Carson Louis J 
Published: February 2020

Abstract
Btpresentative collisionally activated decomposition mass spectrometry/ mass spectrometry spectra of omethoate, parathion, and azinffeas- methyl pesticides are described. Crude and cleaned up extracts af strawberries or lettuce fortified at the 0.2 ppm level with omethoate, parathion, and azinphos-methyl were examined using the direct exposure probe. Cleaned up extracts produced better data because the large overburden of interfering coextractives was removed
Classification of Octadecyl-Bonded Liquid Chromatography Columns
Authors: Walters Milda J 
Published: February 2020

Abstract
The differences in performance characteristics exhibited by columns available under the same octadecyl (C-18) label cause difficulties for the authors and users of official methods. This paper presents a simple scheme for classifying C-18 columns on the basis of the 2 predominant reverse phase retention mechanisms—hydrophobic and silanophilic interactions, which are dependent on the hydrocarbon coverage and the unreacted silanol sites, respectively. Hydrophobic interactions are represented by the ratio of anthracene k : benzene k in an acetonitrile-water (65 + 35) mobile phase. The unreacted silanols are represented by the /V,/V-diethyltoluamide k : anthracene k ratio with acetonitrile as the mobile phase. Column efficiency, which is largely dependent on particle size and packing technique, is included as a third classification criterion. Twelve brands of C-18 packings were subjected to this test scheme and qualitatively classified into 3 major groups on the basis of 3 criteria: hydrophobicity index, free silanol index, and efficiency. This scheme is intended as an aid in the selection of similar or equivalent columns and in defining the type of column suitable for an analytical method.
Determination of Anatoxin M, in Milk and Milk Products Contaminated at Low Levels
Authors: Dominguez Lucas , Blanco Jose L , Gomez-Lucia Esperanza , Rodriguez Elias F , Suarez Guillermo 
Published: February 2020

Abstract
A new method is described for the determination of aflatoxin M, in milk and dairy products by thin layer chromatography. The main characteristic is the extraction system using an alkaline solution. Lipids are removed by centrifuging at low temperatures, and the aflatoxins are then extracted with CHC13. The method has 2 options: Technique II (detection limit 0.02 ppb) requires cleanup on a chromatographic column; this is not necessary in Technique I (detection limit 0.1 ppb). The recovery rate in both techniques is over 92.8% in milk and yoghurt. This method may also be used for other aflatoxins. Because of the advantages of the method, Technique II is recommended for aflatoxin M1, control in milk, where a low detection limit is necessary. Technique I is proposed for experimental aflatoxin production studies in dairy products, which require analysis of a large number of samples but which do not require a very low detection limit.
Liquid Chromatographic Determination of Aflatoxicol in Porcine Liver
Authors: Tyczkowska Krystyna , Hutchins James E , Hagler Winston M 
Published: February 2020

Abstract
A liquid chromatographic (LC) method for determination of aflatoxicol in porcine liver was developed. Liver sample is homogenized with water, diluted with saturated Na2S04 solution, and extracted with acetone. After filtration, less polar interferences are removed by partition with isooctane. Aflatoxicol in the aqueous fraction is partitioned into CHC13. The extract is dried over anhydrous Na2S04 and evaporated nearly to dryness at 35°C under a gentle flow of dry filtered air or nitrogen. Residue is dissolved in CHCl3-hexane and applied to a hexane-activated silica cartridge. The cartridge is washed with hexane-CHClj, then aflatoxicol is eluted with CHCl3-acetone. Purified extract is evaporated to dryness, dissolved in methanol, and analyzed by C18 reverse phase liquid chromatography using a water- CHjCN-acetic acid mobile phase and fluorescence detection. Recovery of aflatoxicol from spiked liver samples at levels ranging from 0.25 to 4.0 ng aflatoxicol/g wet tissue averaged 92% with a limit of detection of about 0.1 ng aflatoxicol/g liver.
Determination of Reserpine and Rescinnamine in Rauwolfia serpentina Preparations by Liquid Chromatography with Fluorescence Detection
Authors: Cieri Ugo R 
Published: February 2020

Abstract
A method is presented for the determination of reserpine and rescinnamine in Rauwolfia serpentina powder or tablets by liquid chromatography (LC) with fluorescence detection. The sample is dispersed in CH3OH, 0.5N H2S04 is added, and the mixture is extracted with five 30 mL portions of CHC13. The extracts are separated from interfering materials on a Celite-O.IN NaOH column, and the eluates are collected in 50 mL CH3OH. After complete removal of the CHC13, reserpine and rescinnamine are determined by liquid chromatography on a normal phase column with CH3OH as the mobile phase. Because reserpine and rescinnamine produce a single peak, chromatograms are obtained at different wavelengths. Reserpine is determined at an excitation wavelength of 280 nm and an emission wavelength of 360 nm. Rescinnamine is determined at an excitation wavelength of 330 nm and an emission wavelength of 435 nm. Recovery studies were conducted at 2 different levels to simulate 100 and 50 mg Rauwolfia serpentina tablets. Samples of Rauwolfia serpentina powders and tablets were also examined, and the results were compared with those obtained by the current AOAC official method. The proposed method is applicable to the analysis of ground composites and individual tablets.
Analysis of Selected Drug Formulations for Volatile Nitrosamines
Authors: Dawson Brian A , Lawrence Robert C 
Published: February 2020

Abstract
A number of selected drug formulations on the Canadian market were analyzed for A'-nitrosodimethylamine (NDMA) and /Y-nitrosodiethylamine (NDEA) content by using a gas chromatograph interfaced to a thermal energy analyzer (GC/TEA). Of the 34 formulations analyzed, NDMA was found in 21 at levels up to 12 ppb and NDEA was found in 11 at levels up to 0.6 ppb. In many cases, the drug entity in the formulation did not contain the precursors for the observed nitrosamines.