bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Performance Liquid Chromatographic Determination of Dielofop-Methyl
Authors: Stringham Rodger W , Bennett Brian R 
Published: February 2020

Abstract
Diclofop-methyl is diluted in acetonitrile-2% acetic acid (70 + 30) and chromatographed on a reverse phase C-18 column. The anaìyte is eluted by an acetonitrile- 2% acetic acid mobile phase and detected at 280 nm. The method was validated by testing precision, linearity, and recovery. Precision and linearity were excellent (% RSD = 0.55, r2 = 0.9997). A multiple standard addition to a pool of formulation samples showed the method to have excellent recovery (99%) and to be free of matrix interferences
Gas-liquid Chromatography and Nitrogens-Phosphorus Detection of N-Nitroso-di-n-Propylamine in Trifluralin Products
Authors: Maybury Ronald B , Grant Ralph G 
Published: February 2020

Abstract
A method is described for the determination of trace levels of N-nitroso-di-n-propylamine (NDPA) in trifluralin herbicide formulations. Following sample extraction, NDPA is separated on a silica gel column and determined by gas-liquid chromatography with a nitrogen-phosphorus detector (NPD). A comparison between the results obtained using this detection system and the thermal energy analyzer (TEA) for 0.5-5 ppm levels of NDPA in 17 samples showed no significant differences. Close agreement was also demonstrated with the results obtained by high resolution gas-liquid chromatography/mass spectrometry (GLC/MS). The minimum detectable amount of NDPA with the NPD was 5 pg, for the TEA system 50 pg, and for high resolution GLC/MS 100 pg. A number of other nitrosamines were detected by all systems in one sample but these were not fully characterized. The nitrogen-phosphorus detector is useful for monitoring traces of NDPA in trifluralin when preceded by cleanup on a silica gel column.
Liquid Chromatographic Determination of Glyphosate Technical and Its Formulation: Collaborative Study
Authors: Burns Arnold J ,   Collaborators:, Audino J B , Bennett O O , Gale G T , Glinski R , Owens M E , Parker J J , Peake A , Rowe N , Sorensen E V , Torma L , Valange B M 
Published: February 2020

Abstract
An HPLC method for the determination of glyphosate in formulation and technical samples has been subjected to a collaborative study with 12 laboratories participating. This method requires no sample pretreatment. Samples were dissolved in mobile phase, injected directly using a fixed-volume loop, and quantitated by an external standard technique. Compounds were separated on a strong anion exchange column with a water-methanol (96 + 4) mobile phase that was 0.0062M in KH2P04 and adjusted to pH 1.9 with 85% H3PO4, and detected with a variable wavelength UV detector at 195 nm. Calculations were made using peak areas. The collaborative study involved 3 pairs of matched samples with single determinations on each sample: Roundup herbicide, a technical intermediate, and technical glyphosate. The coefficients of variation for the 3 pairs were 1.70, 0.88, and 0.90%, respectively. The method has been adopted official first action.
Novel Method for Estimation of Chlorinated Pesticide Residues in Milk
Authors: Adachi Kazuhiko , Ohokuni Nobuyuki , Mitsuhashi Takao , Yoshida Masashi 
Published: February 2020

Abstract
A new, simple, and rapid procedure for determining chlorinated pesticide residues in milk is described. The entire acetonitrile extract from milk is passed through a 0.5 g activated charcoal chromatographic column. Chlorinated pesticides adsorbed on the charcoal are eluted with 100 mL acetone-hexane (1 + 1). The eluate is washed with water and 1% sodium carbonate solution, and chlorinated pesticides are extracted with hexane. The extract is concentrated and measured by electron capture gas chromatography. Recoveries from 50 mL milk samples fortified with 0.04-1.6 μg of different BHC isomers, 0.05-2 μg DDT and its metabolites, and 0.05-0.5 μg dieldrin ranged from 86.9 to 103.2%.
Gas Chromatographic Determination of Mixtures of Captan, Folpet, and Captafol
Authors: Gilvydis Dalia M , Walters Stephen M 
Published: February 2020

Abstract
A gas chromatographic procedure, using electron capture detection, has been studied and found to be applicable for determining 3 structurally similar fungicides, captan, folpet, and captafol, which are often found in combination in certain foods. Eight liquid stationary phases (AN-600, OV-25, OV-101, OV-210, OV-225, QF-1, SP-2401, and XE-60) were evaluated. A fluorosilicone stationary phase of moderate polarity, SP-2401, was best suited for column stability, response, resolution of captan and folpet, and freedom from on-column decomposition of the 3 fungicides.
Mixed Acid Solubilization Procedure for Determination of Total Mercury in Food Samples
Authors: Marts Ronald W , Blaha John J 
Published: February 2020

Abstract
A mixed acid solubilization procedure has been developed for the determination of total mercury in food samples. This procedure has eliminated the problem of mercury loss from samples that are high in lipid or carbohydrate content. The solubilization is rapid and quantitative and can be used for a wide range of food items.
Ion-Pair Liquid Chromatographic Determination of Uncombined Intermediates in Three Synthetic Food Colors
Authors: Lancaster Frank E , Lawrence James F 
Published: February 2020

Abstract
Uncombined intermediates are determined in samples of food colors by reverse phase liquid chromatography with a mobile phase containing tetra-n-butylammonium phosphate. The intermediates are separated from the primary dyes and are quantitated by using known standards. The intermediates naphthionic acid and R-salt (2-naphthol-3,6-disulfonic acid, sodium salt) were determined in spiked samples of Amaranth with recoveries of 98-102%. Similar results were obtained for sulfanilic acid and Schaeffés salt (2-naphthol-6-sulfonic acid, sodium salt) in Sunset Yellow FCF (FD&C Yellow No. 6) and for sulfanilic acid and PyT (l-(4-sulfophenyl)-3-carboxy- 5-hydroxypyrazolone) in Tartrazine (FD&C Yellow No. 5) with recoveries of 96-105%. Spiking levels, in all cases, were in the range 0.05-1.0% total intermediates. The method compares favorably with results obtained by either ion-exchange liquid chromatography or cellulose column chromatography for a number of commercial samples.
Rapid Colorimetric Assay of Trimethoprim and Sulfamethoxazole in Pharmaceuticals
Authors: Sanyal Asis K , Laha Dinabandhu 
Published: February 2020

Abstract
A method is described for the direct colorimetric determination of trimethoprim and sulfamethoxazole in pharmaceutical preparations, without prior separation. Estimation of trimethoprim is based on its ion-pair formation with bromophenol blue and subsequent measurement of absorbance of the ionpair at 418 nm. Estimation of sulfamethoxazole is possible without removal of trimethoprim by solvent extraction.
Rapid Liquid Chromatographic Determination of Aflatoxins in Heavily Contaminated Corn
Authors: Hutchins James E , Hagler Winston M 
Published: February 2020

Abstract
A procedure is described for rapid, quantitative determination of aflatoxins B1, B2, G1, and G2 in heavily contaminated corn (&gt;500 μg B1/kg) from field, greenhouse, and growth chamber experiments employing artificial inoculation of corn with Aspergillus flavus. Whole kernel corn is ground to pass a 1 mm screen and mixed before extraction of a water-wetted (25 mL) 50 g subsample with 250 mL chloroform. The filtered extract is diluted 1:1 with hexane and applied to a hexane-wetted (10 mL) disposable silica cartridge. Interferences are removed with chloroform-hexane (1 + 3), and aflatoxins are quantitatively eluted with hexane-acetone (1 + 1). Aflatoxins B1 and G1 are converted to the more intensely fluorescent hemiacetals, B2a and G2a, by treatment with trifluoroacetic acid-water. Derivatized aflatoxins are separated by reverse phase liquid chromatography (LC) and quantitated fluorometrically. Compared with AOAC method I (CB) for corn, using samples containing approximately 50 and 10 000 μg B1/kg, agreement between methods was good at the lower level while the rapid method yielded a considerably larger mean at the higher level. A precision study of 30 replicate samples produced a coefficient of variation of 8.46% at a mean value of 1066 μg B1/kg. The cartridge method was developed for LC analysis of samples that contain &gt;500 μg aflatoxin B1/kg corn, but it may be used to quantitate as little as 10 μg B1/kg with no modification.
Freeze-Dried Mixed Cultures as Samples for Proficiency Tests and Collaborative Studies in Food Microbiology
Authors: Peterz Mats , Norberg Per 
Published: February 2020

Abstract
A method is presented for preparing samples of freeze-dried mixtures of microorganisms for proficiency tests and collaborative studies. The samples may include most microorganisms that are found in routine analysis in food laboratories. Transport of samples during 48 h did not decrease the number of microorganisms, nor was the variability among samples significantly affected by transport. The standard deviation of counts after 5 weeks of storage varied from 0.04 (Staphylococcus aureus) to 0.17 (Clostridium perfringens) log unit. Storage of samples for 10 weeks decreased the number of viable organisms by 0.02-0.43 log unit. Variability among samples increased for Providencia alcalifaciens and Bacillus cereus after 10 weeks of storage. No significant increase was found for the other organisms.
Determination of Lactose in Milk: Comparison of Methods
Authors: Essig Anita M , Kleyn Dick H 
Published: February 2020

Abstract
A new enzymatic method based on the spectrophotometric measurement of reduced NAD+ (β-nicotinamide-adenine dinucleotide) at 340 nm has been evaluated by comparing it with the AOAC copper reduction method. Ten samples of milk containing various levels of lactose were analyzed in duplicate by the enzymatic method, and 5 samples were analyzed by the copper reduction method. Statistical analysis using a factorial design revealed no statistical significance between results obtained by the 2 methods; recoveries were comparable, 97% or greater for all except one sample. There was no relationship between amount of lactose added and percent recovered.
Evaluation of Apple Juice Authenticity by Organic Acid Analysis
Authors: Evans Randall H , Soestbergen Anton W Van , Ristow Karen A 
Published: February 2020

Abstract
An organic acid profile provides valuable information regarding authenticity of apple juice. The presence of D-malic acid is a clear indication of adulteration because this isomer does not occur naturally. Fumaric and citric acid levels above trace amounts are also inconsistent with pure apple juice; therefore, measurement of these organic acids may also be used as an authenticity check. Citric acid, total malic acid, and fumaric acid were determined in a single scan by liquid chromatography (LC) for 30 known pure apple juice samples. The L-isomer of malic acid was measured by an enzyme-specific method, and the D-isomer was calculated as the difference between total malic acid and L-malic acid.
Pesticide, Heavy Metal, and Other Chemical Residues in Infant and Toddler Total Diet Samples. (III). August 1976–September 1977
Authors: Johnson Roger D , Manske Dennis D , New Dallas H , Podrebarac David S 
Published: February 2020

Abstract
The Total Diet Study has been conducted by the Food and Drug Administration, U.S. Department of Health and Human Services, since 1964 to monitor the diet of adults, and more recently the infant and toddler diet, for residues of pesticides and other chemicals. This report presents the residues found in 12 infant and toddler market baskets, i.e., items comprising the average 2-week diet of infants and toddlers, collected in 12 major cities in 4 geographical areas from August 1976 through September 1977. The analyses for each market basket were performed on composites of each of 11 food classes, and the results are presented in a variety of formats. In addition to chemical residues, the market baskets were also analyzed for 6 heavy metals: arsenic, lead, selenium, zinc, cadmium, and mercury. Results of recovery studies conducted with residue compounds of various types are also included in this report. The results for the adult market baskets for the same period are published as a separate report.
Influence of Phosphorus and Calcium on Flame Atomic Absorption Spectrophotometric Determination of Lead in Canned Fish Products
Authors: Serra Teresa M , Serrano J F Vale 
Published: February 2020

Abstract
Lead was determined in the presence of whole multiples of the P/Ca ratio found in Portuguese canned fish by flame atomic absorption spectrophotometry with and without using an ashing aid. Under our experimental conditions, use of the ashing aid eliminates P and Ca interference. Results with real samples, spiked with 1, 2,3, and 4 ppm lead, are presented and statistically treated.
Rapid Column Method for Determination of N-Nitrosodimethylamine in Malt
Authors: Havery Donald C , Perfetti Gracia A , Thomas Fazio 
Published: February 2020

Abstract
A rapid column elution method has been developed for the determination of N-nilrosodimethylamine (NDMA) in malt. The average recovery of NDMA added to malt at the 10 ppb level was 87%. When a single malt sample was analyzed 10 times, the NDMA found averaged 8.1 ppb with a coefficient of variation of 3.93%. In a study of 15 malt samples, data obtained by the column elution method were in good agreement with those from a vacuum distillation method.
Nuclear Magnetic Resonance Spectroscopic Determination of Dicyclomine Hydrochloride in Tablet, Capsule, and Injection Dosage Forms
Authors: Hanna George M 
Published: February 2020

Abstract
A rapid and specific nuclear magnetic resonance (NMR) spectroscopic method was developed for determining dicyclomine hydrochloride in tablet, capsule, and injection dosage forms. The method consists of an extraction step with chloroform, evaporation of the solvent, addition of maleic acid as an internal standard, dissolution of the mixture in deuterated chloroform-deuterated acetone (40 + 60), NMR spectral determination, and integration of the peaks of interest. The concentration of dicyclomine hydrochloride in the dosage form was calculated from the integral values for the peaks of the test compound and the internal standard. The average recovery value ±the standard deviation (n = 5) of dicyclomine hydrochloride added to synthetic samples was 99.7 ± 0.9% (coefficient of variation 0.9%). The assay values for various commercial tablets, capsules, and injectables analyzed by using the proposed method differed in all cases by &lt;1% from those obtained by using the USP XX titrimetric method. There was no interference from stearate, an excipient found in tablets and capsules, or from chloral hydrate, a preservative found in injectables.
Liquid Chromatographic Determination of Benomyl in Wettable Powders
Authors: Stringham Rodger W , Teubert Wyatt E 
Published: February 2020

Abstract
Pesticide formulations containing benomyl are extracted with acetonitrile containing 3% n-butyl isocyanate (BIC) and chromatographed on a reverse phase C-18 column. The equilibrium of benomyl degradation to methyl 2-benzimidazoIe carbamate (MBC) and BIC is driven toward benomyl. Thus, the method offers quantitation of benomyl in its intact form, using a mobile phase of acetonitrile-2% acetic acid (80 + 20) and detection at 290 nm. This assay was evaluated for linearity, precision, recovery, stability, and matrix effects. Linearity checks of standard solutions and spiked samples yielded coefficients of determination, r2, of 0.9996 and 0.9998, respectively. Quadruplicate analysis of 5 benomyl formulations gave an average relative standard deviation of 1.95%. A multiple standard addition plot revealed the absence of matrix effects. Mean recovery of standard from the sample pool was 95% with a standard deviation of 3.5%. Samples chromatographed 2 weeks after extraction indicated excellent analyte stability.
Effect of Solvent Composition on Aflatoxin Fluorescence
Authors: Chang-Yen Ivan , Stoute Valerie A , Felmine Jane B 
Published: February 2020

Abstract
The influence of the chloroform-methanol solvent system on the fluorescence of aflatoxins Bi, B2, Gj, and G2 was investigated. Fluorescence intensity is markedly affected by solvent composition. The formation of excited state dimers and ionization are proposed to explain the effects observed.
Rapid Liquid Chromatographic Determination of Clopidol in Chicken Muscles
Authors: Mtema Canutte A , Nakazawa Hiroyuki , Takabatake Eigo 
Published: February 2020

Abstract
A simple, rapid, and sensitive liquid chromatographic method is described for the quantitative determination of trace amounts of clopidol (3,5- dichloro-2,6-dimethyl-4-pyridinol) in chicken muscles. Clopidol was extracted from tissues with acetonitrile and the extract was cleaned up on an alumina column and separated on an anion exchange column, using 0.5% acetic acid in methanol as eluant. The solvent in the eluate was evaporated and the residue was dissolved in methanol containing benzamide as internal standard. Clopidol was separated on a Zorbax ODS column (4.6 × 250 mm) by using acetonitrile–0.05M phosphate buffer, pH 7.0 (15 + 85 v/v%), and detected at 270 nm with 0.005 AUFS. Recoveries of clopidol added to chicken tissues at levels of 0.02, 0.05, and 0.1 μg/g were 94.8, 94.8, and 97.0%, respectively. This method is applicable to levels as low as 0.01 ppm clopidol in chicken muscle.
Liquid Chromatographic Determination of Acetaminophen in Multicomponent Analgesic Tablets
Authors: Krieger David J 
Published: February 2020

Abstract
A simple, rapid LC method is presented for the separation and determination of acetaminophen in analgesic preparations containing up to 6 additional active components. The method uses a C18 reverse phase column, methanol–0.75% acetic acid (1 + 3) mobile phase, and photometric detection in the ultraviolet region. Acetaminophen was effectively separated from chlorpheniramine maleate, phenylephrine hydrochloride, caffeine, salicylamide, aspirin, and phenacetin, as well as from salicylic acid, a degradation product of aspirin. Typical chromatograms of the separation of acetaminophen from the above compounds in synthetic mixture and in commercial multicomponent analgesic preparations are presented, along with reproducibility and recovery data.
Gas Chromatographic Determination of Fluazifop-butyl in Formulations: Collaborative Study
Authors: Bland Peter D ,   Collaborators:, Chenery L , Ellis N , Firestone L , Himley R , Hindle R , Hodgins E , Jung P , Jurgens D , King W , Owen M , Parker R , Sasser S , Winstead G , Wood G 
Published: February 2020

Abstract
A method is described for the determination of butyl 2-(4-(5-trifluoromethyl- 2-pyridinyloxy)phenoxy) propanoate in technical and formulated material by gas chromatography (GC). Samples of technical or formulated material are dissolved in methylene chloride containing dibenzyl succinate as internal standard. The solution is injected into a gas chromatograph fitted with a flame ionization detector and a 6 ft × 2 mm glass column. The column is packed with 3% OV-17 on 100–120 mesh Chromosorb WHP and is maintained at 230°C. Peak areas obtained at the retention times of the internal standard and the active ingredient are measured with an integrator. The quantity of fluazifop-butyl is determined by comparing the internal standard and active ingredient peak areas with the peak areas obtained from a calibration solution containing known amounts of internal standard and pure active ingredient. Four samples were chosen for collaboration: technical fluazifop-butyl, a 4 lb/US gal. emulsifiable concentrate, a 560 g/L oil concentrate, and a 5% granular. Fourteen collaborators carried out replicate determinations on each sample. Coefficients of variation between laboratories were 0.80 for the technical, 0.88 for the emulsifiable concentrate, 1.03 for the oil concentrate, and 2.04 for the granular. Parallel peak height determinations showed substantially higher coefficients of variation for all except the granular sample. The method has been adopted official first action.
Dry Column-Thermal Energy Analyzer Method for Determining N-Nitrosopyrrolidine in Fried Bacon: Collaborative Study
Authors: Fiddler Walter , Pensabene John W , Gates Robert A , Phillips John G ,   Collaborators:, Benson M J , Galeener C , Goldstein M M , Greenfield E , Havery D , Meyer K , Phillippo T , Seaman S , Sen N P , Webb C , White G 
Published: February 2020

Abstract
A dry column method for isolating N-nitrosopyrrolidine (NPYR) from fried, cure-pumped bacon and detection by gas chromatography-thermal energy analyzer (TEA) was studied collaboratively. Testing the results obtained from 11 collaborators for homogeneous variances among samples resulted in splitting the nonzero samples into 2 groups of sample levels, each with similar variances. Outlying results were identified by AOAC-recommended procedures, and laboratories having outliers within a group were excluded. Results from the 9 collaborators remaining in the low group yielded coefficients of variation (CV) of 6.00% and 7.47% for repeatability and reproducibility, respectively, and the 8 collaborators remaining in the high group yielded CV values of 5.64% and 13.72%, respectively. An 85.2% overall average recovery of the N-nitrosoazetidine internal standard was obtained with an average laboratory CV of 10.5%. The method has been adopted official first action as an alternative to the mineral oil distillation-TEA screening procedure.
Liquid Chromatographic Determination of Chlortetracycline in Premixes
Authors: Howell Harry R , Rhodig Lori L , Sigler Alan D 
Published: February 2020

Abstract
A liquid chromatographic method for determination of chlortetracycline in premixes has been developed and compared with the AOAC cylinder plate method (42.211 (1980)). Chlortetracycline is extracted with an acid–acetone solution, clarified, and chromatographed on a Vydac 201TP reverse phase column with UV detection at 280 nm. The mobile phase consists of water–dimethylformamide (88 + 12, v/v) containing 0.001M disodium EDTA, 0.05M citric acid, 0.013M sodium citrate, and 0.1M potassium nitrate. Results were linear over a broad concentration range and free from interferences from compounds normally found in premixes. Samples of chlortetracycline premixes were assayed by both this method and the AOAC method with excellent correlation between the 2 methods.
Reverse Phase Liquid Chromatographic Determination and Confirmation of Aflatoxin M1 in Cheese
Authors: Hisada Kazuo , Terada Hisaya , Yamamoto Katsuhiko , Tsubouchi Haruo , Sakabe Yoshio 
Published: February 2020

Abstract
A systematic method is proposed for determination and confirmation of aflatoxin M1 in cheese by liquid chromatography (LC). A sample of cheese is extracted with chloroform, cleaned up on 2 silica gel columns followed by a Sep-Pak C18 cartridge, and chromatographed on a 5 μm octadecyl silica column with fluorometric detection. The sample extract or standard is treated with n-hexane–trifluoroacetic acid (TFA) (4 + 1) for 30 min at 40°C. Analysis by LC with TFA-treatment of the extract provides quantitative data. Multiple assays of 5 samples of Gouda cheese spiked with aflatoxin M1 at levels of 0.5, 0.1, and 0.05 ) ng/g showed average recoveries of 93.2, 91.6, and 92.4%, with coefficients of variation of 2.63, 3.97, and 4.52%, respectively. Assay of 5 naturally contaminated cheeses resulted in 0.051–0.448 ng/g of aflatoxin M1. Limit of quantitation is about 0.01 ng/g. The identity of aflatoxin M1 is confirmed by treating aflatoxin M1 or the M2a. derivative with TFA-methanol (or ethanol) (3 + 1). The TFA-methanol reaction products of M2a could be detected quantitatively.