bluuebunny/crossref_metadata_2025 huggingface dataset:
Extraction and Thin Layer Chromatographic Confirmation of Urine Residues from Food Packaging Materials
Authors: Thrasher Joel J
Published: February 2020

A collaborative study has been conducted on a modified method for the extraction and thin layer chromatographic identification of urine residues on food packaging materials. The modifications involve changes in sample extraction equipment, prewash solvent, sample extract spotting, and plate development. In the collaborative study, 41 of 42 spiked and blank samples were identified correctly. The method has been adopted as official first action.
Gas Chromatographic Measurement of Benzoyl Peroxide (as Benzoic Acid) in Cheese
Authors: Karasz Albert B , DeCocco Frank , Maxstadt John J
Published: February 2020

Benzoyl peroxide bleach, added to cheese, is estimated by gas chromatographic determination of benzoic acid, its principal reduction product. Copper is added to the acidified ether extract of the cheese to reduce the residual bleach, and solvent partitioning and permanganate treatment are used for purification. The benzoic acid is transferred to chloroform containing lauric acid as an internal standard and determined by flame ionization gas chromatography, with a column containing 5% FFAP + 0.5% H3PO4 on Chromosorb W. The average recovery of added benzoyl peroxide was 82.0% and the standard deviation was 0.0128. The occurrence of benzoic acid of microbial origin in cheese poses a problem in accurately determining added benzoyl peroxide from the benzoic acid found in a sample.
Influence of Brand of Dialysis Tubing on a Quantitative Technique for Determining Alkaline Phosphatase Activity of Milk
Authors: Kleyn Dick H , Jakubowski Joseph
Published: February 2020

A study was conducted to determine the influence of brand of dialysis tubing on the official first action method for alkaline phosphatase activity of milk, 16.B01—16.B05. Two brands of tubing were compared: seamless regenerated cellulose tubing and membrane tubing. Analyses were performed in quintuplet on 8, 5, and 5 samples of milk containing about 0.10, 0.25, and 0.50% raw milk, respectively. Two trials were also conducted to compare the rates of dialysis, using about 0.25% raw milk. An analysis of variance of the data showed that the brand of tubing did have a significant ( P< 0.05) influence on resulting absorbance values, particularly at the higher levels of phosphatase activity. Rates of dialysis were found to agree within ± 0.07 μg phenolphthalein/hr during the 3 hr incubation specified. The modified method has been adopted as official final action.
Stability-Indicating Spectrophotometry Determination of Morphine in Injectable Solutions Containing Bisulfite
Authors: Hundley Harvey K , Castillo Gabriel D
Published: February 2020

Morphine in injectable preparations mar undergo reaction with bisulfite when this is used as an antioxidant in the formulation. A simple chromatographic procedure has been developed for the separation of morphine from its oxidation products and from the morphine-bisulfite interaction products. Neutral or acidic impurities are removed from a pH 4.3 buffered sample by elution of a partition chromatographic column with ether. An ether solution of di-(2- ethylhexyl) phosphoric acid is then used to elute the morphine as the cationic component of the ion pair. This fraction is extracted with dilute sulfuric acid to dissociate the ion pair and transfer the morphine to the acid solution for spectrophotometric determination. Multiple analyses of a commercial morphine sulfate formulation gave 101.2±0.3% of declared. Assays by 5 analysts of another commercial preparation and a laboratory preparation gave, respectively, an average of 99.6±2.7% of declared and an average recovery of 90.4±0.5%. The latter, containing 7 mg bisulfite/ml, or 7 times as much as the commercial formulations, shows significant bisulfite-induced decomposition.
Rapid Screening Method for Examining Corn and Corn-Derived Products for Possible Aflatoxin Contamination
Authors: Barabolak Roman , Colburn Charles R , Smith Robert J
Published: February 2020

Aflatoxins were extracted from the sample by high-speed blending with aqueous acetone, purified with ammonium sulfate, re-extracted into benzene, evaporated to dryness, and redissolved in chloroform-acetone. The final solution was subjected to descending minicolumn chromatography through successive layers of alumina, silica gel, and Florisil, and the aflatoxin band was visualized by fluorescence. The method requires only 35—40 min, and results are semiquantitative.
Determination of Chlorophenoxy Acids in Formulations by Gas-Liquid Chromatography of Their Trimethylsilyl Derivatives
Authors: Collier Richard H , Grimes Gregory S
Published: February 2020

A rapid, precise, and specific method for the analysis of free acid and amine salt formulations of chlorophenoxy acids has been developed. Samples containing the amine salts are prepared by addition of dioxane and removal of the water/dioxane azeotrope by rotary evaporation. The trimethylsilyl esters are prepared by incubation of free acids or the above dry residues with N,O-his (trimethylsilyl) acetamide. The esters are chromatographed on 5% SE-30 on 80–100 mesh Chromosorb W with column temperature programming, using pyrene as an internal standard. The method has undergone a ruggedness test which showed very little sensitivity to changes in many of the chromatographic and derivatization conditions. The method was compared to the official final action infrared method for 2,4-D amine salt formulations, 6.A15–6.A19, and to a modified infrared method using the C–CI stretching band at 15.6 μm for measurement. The official method gave a relative standard deviation of 9%, while the modified infrared method and the gas chromatographic method gave relative standard deviations of 1.2 and 1.0%, respectively. The gas chromatographic method resulted in values not significantly different from those of the official method. With the modified infrared method, high results were obtained for some samples, presumably due to the presence of chlorine-containing compounds other than 2,4-D. Recovery of acids and amine salts for the gas chromatographic method is 100.5±1.0%. The method distinguishes between MCPA, MCPP, 2,4-D, 2,4- 5-T, silvex, and 2,4-DB.
Universal Chromatographic-Colorimetric Method for the Determination of Trace Amounts of Polyvinylpyrrolidone and Its Copolymers in Foods, Beverages, Laundry Products, and Cosmetics
Authors: Frauenfelder Lewis J
Published: February 2020

A chromatographic-colorimetric method has been developed for the determination of trace amounts of polyvinylpyrrolidone (PVP) and its copolymers in foods, beverages, laundry products, and cosmetics. Products containing the PVP are passed through a chromatographic column and the PVP is adsorbed at the top of the column. The column is prepared from silica gel if the sample is soluble in 40% acetic acid solution while Micro-Cel E is used when the sample is soluble in a 50% ethanol solution. The PVP adsorbed on the column is then treated with Vital Red dye and the PVP-dye complex thus formed is eluted with TV-methyl pyrrolidone and measured colorimetrically. From the data obtained it is apparent that the method can detect as little as 0.1 ppm with a reproducibility of ±5% of the amount present.
Chemical Analysis of Tetracycline Residues in Animal Tissues
Authors: Ryan John Joseph , Dupont Jo Anne
Published: February 2020

The common tetracyclines (TCs) which are used in agriculture, tetracycline, oxytetracycline, and chlortetracycline, are analyzed in animal tissues by using chemical-physical methods. Tissue from chicken, beef, pork, or fish is blended in aqueous HC1 and centrifuged. The supernate is adsorbed on an Amberlite X AD-2 column, the column is washed with water, and the TCs are eluted with methanol. For levels of TCs greater than 0.5 ppm in tissues and milk, the concentrated residue is spotted on a thin layer plate coated with kiesclguhr. The amount of TCs present on the developed plate is estimated by comparison of the fluorescence with standards spotted concurrently. Recovery of all 3 TCs from samples fortified at levels of 0.5-2 ppm is 45-80%. For levels less than 0.5 ppm, the residue from the Amberlite column is dissolved in pH 9 aqueous solution containing calcium ions and barbital, TCs are extracted into chloroformethanol, and the concentration is estimated on thin layer plates. Recoveries of TCs from various tissues at levels of 0.1–0.5 ppm are 10–35%.
Nuclear Magnetic Resonance Analysis of Pharmaceuticals. XIII. Carbromal and Bromural in Tablets
Authors: Turczan John W
Published: February 2020

A new procedure for a rapid quantitative analysis of carbromal and bromural in tablets is described. The method is based on measurement of the nuclear magnetic resonance (NMR) signal of each compound in a carbon tetrachloride- pyridine solvent mixture (2+1), with hexamethylcyclotrisiloxane as an internal standard. A standard deviation of 0.7% for carbromal and 0.5% for bromural was obtained on synthetic mixtures. The NMR spectrum provides a specific means of identification for these 2 compounds.
Gas-Liquid Chromatographic Method for the Determination of Milk Fat in Cocoa Butter Extracted from Milk Chocolate
Authors: Iverson John L
Published: February 2020

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Inhalation Toxicology
Authors: Macfarland Harold N
Published: February 2020

Two kinds of problems associated with developing standardized procedures for the safety evaluation of new compounds are identified. The first of these is the question of the desirability of using such standard methods. It is concluded that a basic set of procedures is to be recommended, but this should be supplemented with special tests as may be indicated. The second problem is connected with the technical difficulties of any given type of assay and is normally dealt with in terms of the state of the art at the time. Assays by the inhalation route tend to be custom designed and do not follow standard protocols. One of the causes of this situation is the propensity of individual investigators to design de novo the equipment used to effect exposure of animals to airborne substances. Second, some confusion exists because investigators do not always appreciate that the concentration-time product is not the same as the true dose received by the exposed subjects and this may lead to anomalies when dose-response relationships are being characterized. It is suggested that interlaboratory studies be undertaken to ascertain the variability that might be expected in independent assays of inhalation toxicity.
Comparison of Two Formulations of Acid Orange 12 for the Determination of Protein in Milk
Authors: Sherbon John W , Fleming Richard
Published: February 2020

A new formulation of Acid Orange 12 reagent solution for the determination of protein, using 16.037–16.041, has been tested for linearity of response and dye binding capacity. A total of 13 fluid dairy products and one nonfat dry milk were collaboratively studied by 5 laboratories, each using both the old and the new dye solutions. Separate calibration curves were prepared for each dye solution. Analysis of variance (mixed model) showed that the dye solution and the dye solution × sample interaction were nonsignificant sources of variation. Laboratories were a significant source; the estimated standard deviation due to laboratories was 0.023% protein. It appears that very slight differences in calibration curves exist in the different laboratories, but it is not known whether this is associated with the old or new solutions. The new formulation has been adopted as official first action for use in method 16.037–16.041.
Electrophoretic Method for Studying Proteins in Beer
Authors: Gorinstein Shela
Published: February 2020

The proteins in beer were concentrated by the tannin-caffeine method, followed by electrophoresis on agar gel to separate 7 protein fractions: albumin, glutelin-1, gIutelin-2, β-globulin, and α-, β, and γ-hordein. Emission spectroscopy and spectrophotometry of electrophoretically separated proteins revealed ferro- and cuprometal-protein complexes. Analysis of the data shows that beer clarification decreases the content of the trace elements (iron, copper, calcium, and oxalate ion) and that of total protein and protein fractions (albumin, β-globulin and α-, β; and γ-hordein).
Automated High-Pressure Liquid Chromatographic Assay of Robenidine Hydrochloride
Authors: Zagar John B , Ascione Peter P , Chrekian George P
Published: February 2020

High-pressure liquid chromatography has been applied to the separation and analysis of robenidine hydrochloride in the presence of its chemical precursors. It provides a rapid and specific method for the analysis of robenidine in technical material as well as feed premixes and is capable of distinguishing the intact drug from its degradation products. The chromatographic system employs a mixture of methanol, acetic acid, and methylene chloride as the mobile phase and a controlled pore glass as the stationary phase. Sample manipulation has been automated in 2 ways. In the first, manually prepared samples are automatically injected onto the column for separation and quantitation. In the second, a totally automated sample handling system, weighed samples are extracted, diluted, filtered, and then injected onto the column, all in a sequential manner. These procedures are capable of giving quantitative results at a rate of 10 samples/hr with a relative standard deviation of 1.13%.
Gas-Liquid Chromatographic Determination of IV-Octylbicycloheptene Dicarboximide
Authors: Meinen Vernon J
Published: February 2020

A gas-liquid chromatographic (GLC) method is described for the quantitative determination of /V-octylbicycloheptene dicarboximide (MGK 264 synergist) in technical materials and in various formulations. The samples are diluted with acetone and analyzed by GLC, using a flame ionization detector and a column packed with OV-1 on Chromosorb W (HP). Preliminary work indicates that satisfactory results can be obtained with the technical material and several different formulations.
Electron Capture Gas-Liquid Chromatographic Method for the Simultaneous Analysis of 2,4-D, Dicamba, and Mecoprop Residues in Soil, Wheat, and Barley
Authors: Khan Shahamat U
Published: February 2020

A method has been developed for the simultaneous analysis of 2,4-D (2,4-dichIorophenoxyacetic acid), dicamba (2-methoxy-3,6-dichlorobenzoic acid), and mecoprop (MCPP; 2-[(4- chloro-o-tolyl) oxy] propionic acid) residues in soil, wheat, and barley. Soil and crop samples are extracted with acidic acetone and methanol, respectively. The extracts in diethyl ether are esterified with diazomethane and cleaned up by passing through a Florisil column. Extracts are analyzed by gas-liquid chromatography, using an electron capture detector to determine 2,4-D and dicamba residues. Mecoprop in the extract is not detected at low levels of concentration. However, bromination of the extract increases the response of the electron capture detector to mecoprop. The method is sensitive to about 0.05 ppm 2,4-D and dicamba and 0.5 ppm mecoprop. Recoveries of these 3 herbicides added to soil, wheat, and barley samples at 0.05, 0.1, 0.5, and 1.0 ppm levels were between 65 and 93% . The method was used for the simultaneous analysis of 2,4-D, dicamba, and mecoprop residues in wheat, barley, and soil samples obtained from fields sprayed with the herbicide formulation Kil-Mor.
Relative Retention Ratios of Ninety-Five Pesticides and Metabolites on Nine Gas-Liquid Chromatographic Columns Over a Temperature Range of 170 to 204ºC in Two Detection Modes
Authors: Thompson John F , Mann Jon B , Apodaca Alfred O , Kantor Edward J
Published: February 2020

Tables of relative retention data are presented for 95 organochlorine and organophosphorus pesticidal compounds at column oven temperatures from 170 to 204°C in 2° increments. Retention values, relative to aldrin or parathion (RRTA A or P) , were found to vary inversely with increasing column temperature for all compounds eluting later than the reference compound, and in direct proportion for those compounds eluting earlier than the fixed reference compound. Studies revealed a linear relationship between column temperature and relative retention ratios; thus, by obtaining precise values by gas-liquid chromatography for a number of pesticidal compounds at 170, 185, and 200°C, a computer program was developed to obtain RRTA A or P values at all 2° increments from 170 to 204CC, the customary limits in the gas-liquid chromatography of pesticides. The tables are valuable in the tentative identification of pesticidal peaks resulting from the chromatography of sample extracts for multiresidue assessment.
Evaluation of Methods for the Determination of Polymers and Oxidation Products of Heated Vegetable Oils: Collaborative Study of the Gas-Liquid Chromatographic Method for Non-Elution Materials
Authors: Waltking Arthur E
Published: February 2020

A method for measuring non-elution materials from a gas chromatographic column has been collaboratively studied. The average standard deviation is 1.8%. It is the first of 2 companion methods which are expected ultimately to provide a means of measuring the polymers and oxidation products of edible fats and oils. Data from some preliminary studies, which have been confirmed by the collaborative study, indicated that only those oils heated in an unnatural manner contained elevated levels of polymers. The collaborated method may be used as a rapid means for screening samples for further study when it is understood that any measurement obtained is a product of the polymers, oxidation products, and unsaponifiable matter of the sample.
Trimming as a Means of Removing Patulin from Fungus-Rotted Apples
Authors: Lovett Joseph , Thompson Ruben G , Boutin Brenda K
Published: February 2020

Penicillium expansum 1071,1172, NRLL 973, and Penicillium patulum ATCC 24550 were inoculated into Red Delicious, Golden Delicious, and Mcintosh apples. The decayed tissue was trimmed from the sound tissue, each fraction was weighed, and the patulin concentration in the juice was assayed by thin layer chromatography. The quantity of patulin in the whole apples and in decayed tissues was calculated and these values were used to determine the percentage of total patulin removed by trimming. The patulin content ranged from 140 to 4880 μg/apple. Trimming removed 93–99% of the total patulin, regardless of incubation temperature, fungus strain, or apple variety. Trimming of defective tissue from fungus-rotted apples could substantially reduce the patulin concentration.
Collaborative Study of Techniques for the Extraction of Iron and Zinc from Fertilizers
Authors: Wherley Sandra K , Jones Clyde E
Published: February 2020

Water, chelate, and acid techniques were compared for the extraction of iron and zinc from fertilizer samples. The water and chelate extractions were studied to offer an alternative to the official final action acid extraction, 2.098(a)–(c); atomic absorption spectrophotometry was the determinative step. The results for 10 samples from 24 laboratories were examined statistically and were sufficiently reproducible for widespread use of the methods. Statistical treatment of the data from the proposed methods compared favorably with that from the official method. Both the water and chelate extraction techniques have been adopted as official first action, supplementary to 2.098.
Collaborative Study of a Microbiological Assay for Lasalocid Sodium in Feeds
Authors: Scheiner Jacob
Published: February 2020

The microbiological cylinder plate assay method for lasalocid sodium reported earlier was studied in a slightly modified form by 7 laboratories. Assay values paralleled recovery values and all data were corrected by the corresponding daily recovery factor for the feed type. Agreement between laboratories for mashes and pellets containing 0.0064, 0.0080, and 0.0096% lasalocid sodium was satisfactory. Coefficients of variation for mashes were 14.6, 9.8, and 10.7% and for pellets, 15.2, 10.9, and 15.6%. The average of the values found for the 3 mashes was 99.4% of the calculated value and for the 3 pellets, 86.5%. The method has been adopted as official first action.
Interference of 2,3,4,4,5,6-Hexachloro-2,5-cyclohexadien-l-one in the Gas-Liquid Chromatographic Analysis of Octachlorodibenzo-p-dioxin in Commercial Pentachlorophenol
Authors: Wilkinson John E
Published: February 2020

2,3,4,4,5,6-Hexachloro-2,5-cyclohexadien-lone (2,5-HCP), if present in commercial pentachlorophenol (PCP), will interfere with the gasliquid chromatographic analysis of octachlorodibenzo- p-dioxin (OCDD). Different columns (10% UCW-98 and 5% OV-1) and temperature programming were tried without success in separation. 2,5-HCP chromatographed alone at 250°C does break down into several components, one matching the retention time of PCP (0.92 min). The major component eluted within 0.06 min of OCDD.
Atomic Absorption Spectrophotometric Determination of Selenium in Animal Feed Premix, Using the Vapor Generation Technique
Authors: Ng Samuel , Mcsharry William
Published: February 2020

An atomic absorption spectrophotometric method, using the vapor generation technique for the determination of selenium in animal feed premixes containing 0.4–0.002% selenium, is described. After the sample was digested in perchloric acid and hydrogen peroxide and reduced with 6M HC1, 3 aliquots of sample, each containing about 0.4 μg Se, were taken for analysis by the standard addition method. Sodium borohydride pellets were used for the generation of selenium hydride. The relative standard deviation of a single determination averaged ±19%.
Collaborative Study of a Potentiometric Method for the Determination of Fluoride in Vegetation
Authors: Jacobson Jay S , Heller Laurence I
Published: February 2020

A collaborative test was performed to evaluate a new potentiometric method for the analysis of fluoride in vegetation. The study was designed to provide estimates of accuracy and within- and between-laboratory precision of a method that employs extraction of fluoride, followed by analysis with an ion selective electrode. A group of laboratories experienced in fluoride analysis was provided with representative aliquots of specially prepared samples of vegetation and a detailed set of instructions. Reference values were established for the fluoride concentrations of vegetation samples prior to their distribution. Nine of the 23 laboratories participating in the study adhered strictly to instructions so the results from these 9 participants were used to evaluate the method. The coefficient of correlation between results from selected laboratories and reference values was 0.999. Deviations from reference values averaged 5.4% and relative standard deviations ranged from about 20% at 24 ppm to about 10% for concentrations >100 ppm fluoride. On the basis of these results, the new method has been adopted as official first action. The method is simpler and faster; it requires less equipment than the current official final action method (25.029–29.035) and can be used to estimate fluoride concentration in the foliage of plants exposed to fluorides in the atmosphere or in soils provided samples contain >10 ppm fluoride. Separate studies indicate, however, that certain samples of vegetation may be refractory to analysis by this potentiometric method. The final action method should be retained until a practical method is developed that is satisfactory for all types of vegetation.
Spectrophotometric Assay of Salsolidine Hydrochloride
Authors: Karawya Mohamed S , Diab Aly M
Published: February 2020

The proposed method is based on the reaction of salsolidine HCl with carbon disulfide and ammoniacal copper sulfate. The resulting salsolidine-copper-dithiocarbamate complex is extracted with benzene and measured spectrophotometrically at 448 nm. The method is applicable for the detection of 40-500 μg salsolidine/5 ml.
Determination of Polybrominated Biphenyl Residues in Dry Animal Feeds
Authors: Fehringer Norbert V
Published: February 2020

A new procedure is described for the determination of polybrominated biphenyls (PBBs) in dry animal feeds and developmental results are discussed. Finely ground feed is packed into a chromatographic column containing Celite and then eluted with methylene chloride. The concentrated extract is cleaned up by elution with petroleum ether through Florisil before gas-liquid chromatographic quantitation. Chromatograms thus obtained were essentially free of the interfering peaks encountered when using AOAC methods for pesticide residues in dry products. Results of feed analyses by the proposed procedure averaged 30% higher than those obtained by AOAC procedures. Recoveries of PBBs from samples fortified at levels of 0.04 to 0.4 ppm ranged from 90 to 104%, with an average of 98%.
The Food and Drug Administration and the Vinyl Chloride Problem‒An Overview
Authors: Schaffner Robert M , Lombardo Pasquale
Published: February 2020

Recent evidence has shown that chronic exposure to vinyl chloride by inhalation may cause cancer in laboratory animals and in man. Its possible oral effects are currently being investigated. The history of the significant events leading to the investigation of this chemical is presented. The current and future activities of the Food and Drug Administration in this area are also described.