bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas-Liquid Chromatographic Method for the Determination of Milk Fat in Cocoa Butter Extracted from Milk Chocolate
Authors: Iverson John L 
Published: February 2020

Abstract
A rapid extraction procedure was selected for obtaining lipids from milk chocolate and a gasliquid chromatographic method was developed for estimating milk fat in chocolate. The milk fat content of milk chocolate can be estimated on the basis of the lauric acid content of the lipid extract of milk chocolate. The method is accurate in detecting 10–30% milk fat, the range of practical interest in cocoa butter. Data were obtained on the fatty acid composition of 8 authentic cocoa butter-milk fat samples, 11 domestic milk chocolates, 11 imported milk chocolates, and 9 miscellaneous chocolates.
Analytical Study of the Volatile Oil of Thymus vulgaris L. Growing in Egypt
Authors: Karawya Mohamed S , Hifnawy Mohamed S 
Published: February 2020

Abstract
The volatile oil of Egyptian Thymus vulgaris L. collected at different stages of growth, before flowering, during flowering, and at fruiting stages, was analyzed by chromatographic and infrared techniques and the results were compared with those of imported thyme oils. The Egyptian oil was richer in linalool and terpene hydrocarbons. Thymol and carvacrol were identified in moderate concentrations when compared with those present in the imported oils. The highest thymol and carvacrol concentrations in the Egyptian oil were reached during the beginning of the flowering stages.
High-Speed Liquid Chromatographic Cleanup of Environmental Samples Prior to the Gas Chromatographic Determination of Lindane
Authors: Larose Richard H 
Published: February 2020

Abstract
A method is described which permits the removal of interfering co-extractives from lindane, using high-speed liquid chromatography. Fractions are collected from the liquid chromatograph for further analysis by gas-liquid chromatography. The cleanup procedure takes less than 5 min and recoveries of more than 90% are obtained. The detection limit for water samples is 5 ng/L.
Determination of Leptophos, Leptophos Oxon, and a Possible Phenolic Photoconversion Metabolite in Rapeseed Grain
Authors: Currie Robert A 
Published: February 2020

Abstract
Whole rapeseed grains were extracted with water-acetonitrile. Following partitioning of leptophos and its 2 metabolites into petroleum ether, the sample extract was cleaned up by graded elution on a silica gel column. The first fraction contained leptophos (O-(2,5-dichIoro- 4-bromophenyl) O-methyl phenylthiophosphonate) and its phenolic metabolite (2,5-dichlorophenol analog of leptophos) which were determined by using a gas chromatograph equipped with a flame photometric detector (526 nm filter). Leptophos oxon was eluted from the silica gel column in a second fraction and determined by using thin layer chromatography and enzyme inhibition detection. Recoveries ranged from 85.6 to 96.7% for leptophos and from 83.4 to 96.9% for its phenolic metabolite at the 2 ppb fortification level. Within the limits of the detection system, leptophos oxon was recovered quantitatively at the 10 ppb level.
Mercury in Commercial Canned Sea Food
Authors: Hall Edward T 
Published: February 2020

Abstract
The mercury content of several brands of different commercial canned sea food products was determined. Results of the study showed that of the sea foods tested, tuna contained the highest concentration of mercury residues. The mercury content of each sample was determined by flameless atomic absorption spectroscopy (AAS) and gas-liquid chromatography (GLC). A comparison of total mercury content by flameless AAS and methyl mercury by GLC showed that 89% or more of the mercury in canned tuna is methyl mercury. Levels of mercury were lower in salmon, shrimp, oysters, clams, sardines, anchovies, cat food, and kippered herring. Results indicate that the GLC method could be used as an effective screening method for tuna samples where flameless AAS is not available.
Automated Fluorometric Assay of Vitamin A in Pharmaceutical Preparations
Authors: Kahan Johan 
Published: February 2020

Abstract
A completely automated method is described for the dilution, extraction, and determination of vitamin A in water- and/or ethanol-soluble pharmaceutical preparations containing 50– 15,000 IU vitamin A/ml. The analytical rate of the method is 30 samples/hr. The coefficient of variation of sequentially analyzed replicates is about 3%. In a semiautomated version, the procedure can also be applied to other pharmaceutical products.
Automated Method for the Analysis of Riboflavin in Milk, with Application to Other Selected Foods
Authors: Kirk James R 
Published: February 2020

Abstract
A continuous flow automated technique was developed for the determination of riboflavin in milk. The determination is based on the measurement of the natural yellow-green fluorescence of riboflavin at an excitation of 436 nm and emission of 510 nm. Blank values are determined for each sample after sodium hydrosulfite reduction of the riboflavin. Mean recovery and standard deviation for riboflavin in milk determined by the continuous flow procedure using internal standards were 9 7% and ± 2.42%, respectively. The recovery value was in good agreement with that determined using a manual procedure, while the standard deviation was 33% less than that found when using the manual procedure. The results from this study indicate that the continuous flow automated procedure for the determination of riboflavin in milk is a simple, quantitative method which eliminates many of the time-consuming analytical steps.
Determination of Sodium Chloride in Smoked Fish by Use of a Sodium Ion Electrode
Authors: McNerney Francis G 
Published: February 2020

Abstract
A simple, rapid procedure is presented for the determination of sodium ion in smoked fish. A sodium ion-selective electrode is used directly on the diluted fish sample. No significant differences were noted in the results obtained by this method, the official chloride titration method, and the flame photometric determination of sodium.
Ion-Selective Electrodes Sensitive to Organic Ions. I. The Saccharin Electrode
Authors: Hazemoto Norio , Kamo Naoki , Kobatake Yonosuke 
Published: February 2020

Abstract
An ion-selective electrode responsive to saccharin was made by dissolving an ion association which exists between iron(II)-bathophenanthroline chelate and saccharin in nitrobenzene. The electrode developed was capable of measuring saccharin ion concentration in the presence of other sweetening substances, e.g., saccharose, glucose, sodium cyclamate, and sorbitol, over the concentration range of 10-1 to 10-5M.
Effects of Collector Probe Irregularities in Electron Capture Gas Chromatography
Authors: Holden Edward R , Hill Kenneth R 
Published: February 2020

Abstract
Barely visible scoring of a cylindrical electron collector probe had profound effects on the performance of an electron capture detector in gas chromatography: Electronic noise was increased greatly, relationship of response to applied voltage was reversed, and optimum distance between the probe and the radioactive source was shifted widely. Imperfections too small for visual detection, although having little effect on noise and response levels, were found to cause serious baseline instability. An instrumental error of as much as ± 50% due to surface irregularities can be eliminated by polishing the collector probe.
Confirmation of Pesticide Residue Identity. VIII. Organophosphorus Pesticides
Authors: Coburn John A , Chau Alfred S Y 
Published: February 2020

Abstract
A chemical confirmation for 5 organophosphorus pesticides is described. After extraction and quantitation by flame photometric detector gas-liquid chromatography (CLC), the organophosphorus pesticides are hydrolyzed in a 10% methanolic-potassium hydroxide solution, followed by derivatization with pentafluorobenzyl bromide to produce the pentafluorobenzyl (PFB) ethers of the phenolic hydrolysis products. The PFB ethers are subsequently fractionated on a silica gel microcolumn, and analyzed by electron capture GLC. The preliminary chromatographic results of the electron capture GLC analysis of the PFB ethers of the phenolic hydrolysis products of several N-methylcarbamates are also presented. As little as 0.01 ppb ronnel and crufomate and 0.10 ppb parathion, fenitrothion, and methyl parathion in a 1 L water sample can be confirmed.
Evaluation of an Automated Dual-Channel Hydroxylamine Assay Procedure for Formulated Penicillin Products. I. Liquid Formulations
Authors: Lane Jonathan R , McClure Foster , Martinez Charles 
Published: February 2020

Abstract
The automated dual-channel hydroxylamine method reported by Stevenson, Bechtel, and Coursen was compared with the official Food and Drug Administration (FDA) manual iodometric method used to determine the potency of formulated penicillin products. In order to assay a wide range of products, the liquid sampler module was used with 4 different flow diagram arrangements for liquid sample solutions. Solid dosage forms, when tested intact, were assayed with a modified SOLIDprep Sampler unit. Some dosage forms were assayed directly from their pharmaceutical market containers via on-line dilution techniques. Some of the problems encountered are described and experimental design as well as methods of statistical analysis are discussed. The method reported has been recommended as an alternative to the official FDA manual procedure. In general, the automated hydroxylamine method compared well in accuracy and precision with the manual iodometric method. Manually diluted autoanalysis lacked the precision of other methods.
Analysis of Fat-Soluble Vitamins. XIII. Chemical Vitamin D Assay in Vitamin D and Multivitamin Preparations1
Authors: Mulder Frits J , Vries Ellen J 
Published: February 2020

Abstract
The chemical vitamin D assay of the USP has been modified for application to preparations containing 200-5,000,000 IU vitamin D/g in the presence of other fat-soluble vitamins. In the modified procedure, interferences from other fat-soluble vitamins, additives in the formulations, and biologically inactive isomers of vitamin D are eliminated by column chromatography on phosphate-treated alumina, polyethylene glycol 600-Celite 545, and granular Florex and a maleic anhydride addition reaction. Furthermore, a 2-component analysis, i.e., reading absorbances at both 500 and 550 nm wavelengths, corrects for irrelevant absorbances. The coefficients of variation for the assay of a number of preparations ranged from 1.5 to 4%.
Colorimetric Estimation of Pantothenates in Formulations
Authors: Karawya Mohamed S , Ghourab Mohamed G , Ibrahim Esther N 
Published: February 2020

Abstract
The ninhydrin method for the colorimetric estimation of pantothenate has been modified by using zinc and hydrochloric acid instead of alkaline hydrolysis. This renders the reaction more rapid and sensitive. The method can detect 50舓200 μg pantothenate/25 ml in formulations and natural products without interference from other vitamins, amino acids, and tetracyclines.
Collaborative Study of the Official AOAC Method for the Determination of Biuret in Fertilizers
Authors: Corominas Luis F 
Published: February 2020

Abstract
The present official first action method for biuret, 2.073-2.075, has been compared with a modified version (larger sample size, vacuum removal of ammonia and ammonium carbonate, and recrystallization of biuret standard) and a colorimetric method using nickel sulfate as the color complexing agent. Five samples containing from 0.4 to 0.9% biuret were collaboratively studied. In general, the modified method yielded better results, based on 515 individual results reported by 7 laboratories.
Gas-Liquid Chromatographic Determination of Ethylenediaminetetraacetic Acid in Pickled Vegetables
Authors: Williams David T 
Published: February 2020

Abstract
A method has been developed for the determination of ethylenediaminetetraacetic acid in pickled vegetables after conversion to its tetramethyl ester. The ester is identified by gas-liquid chromatography and confirmed by gas-liquid chromatography-mass spectrometry. Recoveries from pickled beet samples spiked at 20-250 ppm were 87-74%.
Production of 36C1-Labeled Polychlorinated Biphenyls by Neutron Activation: A Reevaluation
Authors: Greenwald Lewis , Carey Walter E 
Published: February 2020

Abstract
One attempt to prepare radiolabeled Aroclors (commercial mixtures of polychlorinated biphenyls (PCBs)) has involved neutron irradiation to produce 36Cl-PCBs from 35Cl-PCBs via an (n,γ) reaction. However, because of the long half life of 36Cl, the (n,p) reaction forming 35S from 35C1 would predominate, leading to the production of between 5000 and 10,000 times as much 35S-substituted PCBs as 36Cl-PCBs. Also, significant amounts of 32P would be produced. Therefore, it is shown that 36Cl-PCBs cannot be produced from 35Cl-PCBs without the concomitant interference of 35S-substituted PCBs.
Automated Analysis of Vitamin C in Pharmaceutical Products
Authors: Pelletier Omer , Brassard Rene 
Published: February 2020

Abstract
The determination of total vitamin C in the form of both L-ascorbic acid (AA) and dehydroascorbic acid (DHAA) present in pharmaceutical preparations has been automated. Total vitamin C (completely oxidized to DHAA) was determined by reaction with 2,4-dinitrophenylhydrazine while blanks utilized the same reagent after reducing all DHAA to AA. The automated method was applicable to a variety of multivitamin preparations including those containing iron and copper. The mean recovery of L-ascorbic acid added to 11 multivitamin preparations was 99.4% with a coefficient of variation of 2.5%. In the analysis of these products, results obtained by the automated method were essentially the same as those obtained by the original manual method. For preparations containing no copper salts, the results were also comparable to those obtained by titration with 2,6-dichloroindophenoI except in 1 product which contained some DHAA.
Collaborative Study of a Method for Chemical Confirmation of the Identity of Aflatoxin
Authors: Stack Michael E , Pohland Albert E 
Published: February 2020

Abstract
The chemical method for confirmation of the identity of aflatoxin by derivative formation directly on the TLC plate was studied collaboratively by 8 participants. The results show that aflatoxin B1 was confirmed in 17 of 17 sample extracts representing 15 μg aflatoxin B1/kg peanut butter, in 13 of 16 extracts representing 5 μg/kg, and in none of the 7 aflatoxin-free extracts. Collaborators commented that the method was easily performed and gave good results. The method has been adopted as official first action.
Collaborative Study of the Determination of Sorbic Acid in Wine
Authors: Caputi Arthur , Slinkard Karen 
Published: February 2020

Abstract
Eleven collaborators participated in a study of 2 methods for determining sorbic acid in wine. One method utilizes ultraviolet spectrophotometry and the other depends on the colorimetric measurement of a thiobarbituric acid complex. Three different wine types were each spiked with 200, 300, and 400 mg sorbic acid/ L. Average recovery ranged from 97.3 to 107.5% with the thiobarbituric acid method with coefficients of variation from 4.4 to 8.7%. The ultraviolet method gave recoveries from 97 to 103.5% with coefficients of variation ranging from 2.0 to 6.4%. Comments on both methods from collaborators were favorable. Both methods have been adopted as official first action.
Colorimetric Assay of Strychnine and Brucine in Nux Vomica
Authors: Karawya Mohamed S , Hifnawy Mohamed S , Dahawi Hasan S 
Published: February 2020

Abstract
Two colorimetric methods are described for the estimation of strychnine and brucine in nux vomica. The first is a modification of the Karawya and Ghourab method for the determination of strychnine, in which the sensitivity of the color is increased by changing certain conditions of the method. The second was developed for the determination of brucine and is based on measuring the intensity of the violet color produced by treating brucine with nitric acid and methanolic stannous chloride. In the presence of large amounts of strychnine, brucine is isolated prior to colorimetric analysis by a quantitative thin layer chromatographic technique.
Determination of Procaine and Related Local Anesthetics. II. Collaborative Study
Authors: Proctor Joseph B , Doyle Thomas D 
Published: February 2020

Abstract
The ion-pairing chromatographic method reported previously for the isolation and spectrophotometric determination of the local anesthetics, alone and in combination, was studied collaboratively. Three solutions were assayed. One containing procaine as the single active component gave an average recovery of 99.8± 1.7%. A mixture of procaine and tetracaine gave results of 99.3±1.6 and 98.9±8.82%, respectively. A third solution containing procaine and propoxycaine assayed 100.0±1.5 and 99.1±1.9%, respectively. It was shown that low results for tetracaine were due to loss during the final evaporative step. The method for samples containing tetracaine should be studied further. The other methods have been adopted as official first action.
Effect of Particle Size on the Biological Availability of Reduced Iron
Authors: Motzok Ilary , Pennell Murray D , Davies Muriel I , Ross Henry U 
Published: February 2020

Abstract
A sample of reduced iron was separated by air elutriation into several fractions based on particle size; and the relative biological values (RBVs) of 3 fractions containing fine, medium, and coarse particles were determined with rats and chicks, using diets containing either skim milk powder or casein as the major source of protein. The RBV of reduced iron for rats was shown to be dependent on particle size by curative and prophylactic assay procedures, with the source of protein having no marked effect. In contrast to rats, chicks utilized reduced iron to a higher degree, especially the iron from coarse particles. Prophylactic assays with rats indicated that a 3–4 week feeding period from weaning at 21 days of age gave RBVs which were not significantly different from those obtained by repletion of hemoglobin of anemic animals. After 5 weeks on the test diets, however, the rats lost their ability to distinguish between coarse and medium particles of reduced iron when fed with a diet containing casein as the source of protein.
Collaborative Study of a Method for the Determination of Ochratoxin A in Green Coffee
Authors: Levi Colette P 
Published: February 2020

Abstract
A method for the semiquantitative determination of ochratoxin A in green coffee has been studied collaboratively by 11 laboratories. The average recovery for the 7 samples spiked at 3 levels of ochratoxin A was 69.1%, ranging from 60.5 to 85.6%. This is comparable to other visual thin layer chromatographic methods of mycotoxin detection. The method has been adopted as official first action for the determination of ochratoxin A in green coffee beans.
Gas-Liquid Chromatographic Determination of Vinyl Chloride in Alcoholic Beverages, Vegetable Oils, and Vinegars
Authors: Williams David T , Miles Walter F 
Published: February 2020

Abstract
Vinyl chloride in foods is determined by gasliquid chromatography either by direct injection of vinegars and alcoholic beverages or by headspace analysis of vegetable oils. The lower limit of detection is 10–15 ng/ml for direct injection and 5–10 ppb for headspace analysis. Confirmation by gas chromatography-mass spectrometry, single ion monitoring at m/e 62, is possible at 50 ppb for either method. The levels of vinyl chloride found in foods packaged in polyvinyl chloride bottles were 0.0–1.6 μg/ml for alcoholic beverages, 0.0–8.4 μg/ml for vinegars, and 0.3–3.3 ppm for peanut oil.
Collaborative Study of Speaker Identification by the Voiceprint Method
Authors: Smrkovski Lonnie L 
Published: February 2020

Abstract
In the voiceprint method known and unknown voices are compared to determine if they are the same speaker. An unknown voice is recorded over the telephone onto a quality recorder. The known voice is similarly recorded, repeating the questioned message verbatim. An examiner determines, by means of acoustic spectrography and aural analysis, the similarities or differences existing between the known and unknown speakers. A positive conclusion is based on at least 10 pairs of like sounds. Five decisions are available for the examiner to make: positive identification, positive elimination, probable identification, probable elimination, and unable to make a decision with the sample submitted. Seven collaborators, chosen from various parts of the United States, were given recordings of 4 unknown speakers, 2 male and 2 female, to compare with similar recordings of 6 known speakers, 3 male and 3 female. A total of 21 positive identifications and 63 positive eliminations was possible. Twenty correct identifications and 47 correct positive eliminations were made. In 16 tasks, all involving the same unknown sample, collaborators reported they could not make a determination due to the poor quality of the sample. No false identifications were made; however, a trainee examiner, with less than 2 years experience, eliminated a known speaker when in fact a match did exist, thereby falsely eliminating the speaker. Examiners with more than 2 years of experience correctly identified all existing matches. This study indicates that a trained examiner can make very reliable decisions, using the aural and visual methods of comparing known and unknown voices. The voiceprint method has been adopted as official first action.
Collaborative Study of the Glass Wool Filtration Method for the Recovery of Virus Inoculated into Ground Beef
Authors: Larkin Edward P , Tierney John T , Sullivan Robert , Peeler James T 
Published: February 2020

Abstract
A method for estimating viral population levels in ground beef was studied collaboratively in 7 laboratories. The collaborators recovered virus from 6 inoculated samples. Three samples were replicates of the high virus concentration (50 plaque-forming units (pfu)/g) and 3 replicates represented the low concentration (10pfu/g ). Six of the 7 collaborators recovered acceptable levels of virus from the samples. The per cent of variation was 30.6 for the high concentration and 18.5 for the low concentration. Collaborators did not differ from one another significantly in the results obtained for the 10 pfu/g samples, but results from one collaborator were significantly low for the recovery of virus from the 50 pfu/g samples. The results indicate that the glass wool filtration method is adequate for the detection of a number of viruses that may be found in foods. The method has been adopted as official first action.
Effect of FD&C Red No. 3 (Erythrosine) on the Determination of FD&C Azo Color Additives
Authors: Draper Ronald E 
Published: February 2020

Abstract
FD&C Red No. 3 (erythrosine) has been shown to interact with FD&C Red Nos. 2, 4, and 40 and FD&C Yellow Nos. 5 and 6 and thus interfere in the determination of these azo color additives. This interaction is concentration dependent and occurs only in alkaline solution and in the presence of light. Precautions are detailed to minimize this interaction.