bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation on the Thin Layer Chromatographic Development of Corn Extracts with Ethyl Ether
Authors: Trucksess Mary W
Published: February 2020

The separation of aflatoxin from interfering lipids in one rapid thin layer chromatographic development is achieved by selecting the proper combination of a specified type of silica gel and grade of ethyl ether.
Introductory Study of Scanning Electron Microscopy of Elytral Fragments of Stored Product Beetles
Authors: Brickey Paris M , Gecan John S
Published: February 2020

Eleven stored product beetles were examined for surface features of the beetle elytron, using a scanning electron microscope. The 3 characteristics, sculpturing pattern, setae, and setal pits, were well defined and could be used to distinguish the species examined. The scanning electron microscope can give 3-dimensional images at magnifications up to 20,000 ×, in contrast with the light microscope which has a maximum magnification of 1000 ×.
Determination of N-(4-Chlorophenyl)-N´-(2,6-difluorobenzoyl)-urea in Milk by High-Speed Liquid Chromatography
Authors: Corley Calvin , Miller Richard W , Hill Kenneth R
Published: February 2020

A rapid and sensitive method of analysis in which high-speed liquid chromatography was used with ultraviolet absorption detection was developed for determining residues of Thompson- Hayward TH 6040 (N-(4-chlorophenyl)-N'- (2,6-dinuorobenzoyl)urea) in cows' milk. The larvicide is extracted from whole milk with ethyl acetate, and the lipids are removed by partitioning between hexane and acetonitrile. After evaporation of the acetonitrile, the residue is dissolved in ethanol, and aliquots are injected into a liquid chromatograph, using methanol-water (1+1) as the mobile phase in a packed column. Recovery of TH 6040 from cows' milk is essentially quantitative, and no interfering substances appear on the chromatogram. The lowest detectable level was 10 ng. Milk from a cow fed 1 mg larvicide/kg body weight daily in the diet was analyzed by this procedure, and no detectable residues (<0.1 ppm) were found over a 15 week sampling interval.
Determination of 2-Propanol Residue in Some Fruits Dewaxed with Alcohol Vapors
Authors: Calhoun Mary JO , Dellamonica Edward S
Published: February 2020

A quantitative method is described for the determination of 2-propanol in apples and grapes exposed to alcohol vapors. This method was also applied to eggplants. The procedure includes the following: homogenizing the product in a blender and filtering the slurry; weighing an aliquot of the filtrate into a serum bottle containing 1-propanol, the internal standard; equilibrating the liquid and gas phases; sampling the headspace vapor and analyzing by gas-solid chromatography (GSC). A time-temperature study using model alcohol systems indicated that equilibration at 65 °C for 60 min gave the most constant peak area ratios of 2- propanol: 1-propanol as measured by GSC. The peak area ratio was directly proportional to the concentration of 2-propanol over the range 0舓180 ppm. The recovery of 2-propanol added to untreated apple juice was excellent within this range.
Protein Analysis of Feeds, Using a Block Digestor
Authors: Hambleton Larry G , Noel Rodney J
Published: February 2020

A method for the determination of proteins in feeds, utilizing the Technicon® BD-20 block digestor, has been developed. Twenty feed samples are weighed directly into the 250 ml tubes and digested for 35 min after clearing. The temperature of the solution during the digestion and the uniformity of temperature between various holes in the block were determined. The effect of air currents over the tubes was also studied. Six replicate determinations on cottonseed meal, blood meal, soybean meal, tryptophan, and 2 feed samples are reported and compared to results on the same sample analyzed by the official final action Kjeldahl method; good agreement was shown between the methods. The accuracy of the block digestor was confirmed by analyzing 40 routine feed samples by both the block digestor and Kjeldahl methods; results did not show a significant difference when compared by Student's t-test at the 5% level.
Determination of Moisture in Molasses by the Karl Fischer Method, Using Formamide as the Solvent
Authors: Kviesitis Boris
Published: February 2020

The use of formamide as a solvent for the determination of moisture in molasses by the Karl Fischer method reduces the time required for titration which, in turn, increases the accuracy of the method. Formamide has the advantage of dissolving molasses without increasing its water content. It is recommended that the use of formamide in the determination of moisture by the Karl Fischer method be submitted to collaborative study.
Correlation Between Physical Properties and Field Performance of Insecticidal Emulsion Sprays
Authors: El-Refai Abd R , El-Attal Zakaria M , Said Ali A A
Published: February 2020

Commercial and laboratory-prepared insecticide emulsiliable concentrates were tested in the laboratory and in the field to study their physical and chemical characteristics. Distribution of spray emulsion and retained deposits of active ingredients on leaf surfaces are directly related to emulsion stability, amount of emulsifier, and droplet size of spray emulsion. Thus the laboratory tests described for the measurement of the latter 3 properties can be performed before extensive field trials are conducted.
Colorimetric Determination of Mestranol in Combination with Ethynodiol Diacetate
Authors: Wu John Y P
Published: February 2020

Mestranol in combination with ethynodiol diacetate, an oral contraceptive formulation, is isolated from the sample on a partition chromatographic column prior to colorimetric determination. The color reaction which is specific for estrogens is formed by shaking an aliquot of the heptane eluate of mestranol with a 30% methanol-sulfuric acid solution. A collaborative study of the method gave results of 99.8% of added mestranol for the simulated mix and 100.7% of labeled mestranol for the commercial tablet. The method has been adopted as official first action.
Methodology for Enteropathogenic Escherichia coli
Authors: Mehlman Ira J , Simon Nicholas T , Sanders Arvey C , Fishbein Morris , Olson Joseph C , Read Ralston B
Published: February 2020

Pathogenic biotypes of Escherichia coli grow poorly at temperatures greatly different from that of the host. Percentages quantitatively recovered at 42.0, 44.0, 44.5, and 45.5°C in lauryl tryptose broth were 100, 76, 76, and 42, respectively. Corresponding values for 175 strains of varied origin were 98, 89, 82, and 65%. Maximal growth temperature is dependent upon medium. Lauryl tryptose and elevated coliform broths were equivalent in the recovery of small inocula (100 cells/ml) at 41.5–44.5°. Mac-Conkey, enteric enrichment, and Gram-negative broths were inhibitory at corresponding values. Growth at elevated temperature in nutrient broth is enhanced by carbohydrate. Standard lactose enrichment media fail to recover slow lactose fermenters. An acidified glutamic acid medium was unsuitable for recovery of E. coli. The data suggest modification of standard temperatures for the recovery of pathogenic biotypes. Previously recommended analytical methods have been simplified and supplemented. The enhancement of motility in indole-nitrite broth at 35°C is recommended. A 4-tube semiquantitative test is offered for tentative identification of somatic and capsular antigens. Inclusion of Alkalescens-Dispar strains is warranted by their pathogenic behavior. Examination in Shigella and Alkalescens-Dispar sera is required to cover the dysentery-like biotypes. Pathogenic potential cannot be inferred from serotype.
Collaborative Study of Wet and Dry Ashing Techniques for the Elemental Analysis of Plant Tissue by Atomic Absorption Spectrophotometry
Authors: Isaac Robert A , Johnson William C
Published: February 2020

Seven laboratories participated in a collaborative study of wet ashing of plant material with a nitric-perchloric acid mixture and dry ashing at 500°C in order to determine the elements calcium, copper, iron, magnesium, manganese, potassium, and zinc by atomic absorption spectrophotometry. Five different homogeneous leaf tissue samples were analyzed and a synthetic standard solution containing all of the elements studied was included to evaluate sample preparation errors independent of instrument errors. The results indicated that plant tissue preparation by either wet or dry ashing gave similar elemental composition results for the tissues analyzed. The wet and dry ashing techniques have been adopted as official first action.
Limited Collaborative Study of an Optional Method for the Isolation of Light Filth from Fig and Fruit Paste
Authors: Kvenberg John E , Eisenberg William V , King Alfred C
Published: February 2020

The present official first action method for the isolation of light filth from fig and fruit paste, 44.083(a), occasionally yields excessive plant debris on filter papers, which causes difficulty in effectively counting insect filth. The proposed method provides the option of an additional flotation of trapped off material in a Corning percolator. This revision has been adopted as official first action as an alternative to 44.083(a).
Removing the Interference of DDT and Its Analogs in the Analysis for Residues of Poly chlorinated Biphenyls
Authors: Trotter William J
Published: February 2020

A micro scale procedure is described for quantitatively separating polychlorinated biphenyls (PCBs) from DDT and its analogs. DDT and TDE are initially dehydrochlorinated with ethanolic KOH to their respective olefins, DDE and TDE-olefin (l-chloro-2,2-bis(p-chlorophenyl) ethylene). The olefins are then oxidized by Cr03 in acetic acid to the more polar dichlorobenzophenone. PCBs are eluted from a micro Florisil column with petroleum ether. Typical recoveries in the ppm range (based on a 5 g sample) were >80% for Aroclors 1254 and 1260. Recoveries generally were poorer with Aroclors of lower chlorine content and decreased with decreasing quantity of Aroclor present. The DDT group was not quantitatively determined; recoveries averaged ≥60% for the DDT group in the ppm range (based on a 5 g sample). The procedure was successfully applied to samples of Lake Michigan chubs containing residues of PCBs and the DDT group and to extracts of human serum fortified with Aroclors and the DDT group.
Limitation on the Use of Antimony Pentachloride for Perchlorination of Poly chlorinated Biphenyls
Authors: Trotter William J , Young Susan J V
Published: February 2020

Two contaminants are present in commercially available antimony pentachloride (SbCl5) used to perchlorinate polychlorinated biphenyls (PCBs) to decachlorobiphenyl (DCB). DCB is found in the SbCl5 perchlorination reaction blank in which no PCBs were added. Bromononachlorobiphenyl (BNCB) is found after use of SbCl5 to perchlorinate PCBs. Levels of DCB found in the SbCl5 reaction blanks from various distributors ranged from 8 to 972 ng DCB/ml SbCl5. The relationship of the formation of BNCB to amounts of various PCB Aroclors perchlorinated is examined.
Fluorometric Determination of Nitrite in Cured Meats
Authors: Coppola Elia D , Wickroski Alphonse F , Hanna J. Gordon
Published: February 2020

An indirect fluorometric method for determining sodium nitrite in meat products is presented. The extracted sodium nitrite is consumed in a diazotization reaction with a measured excess of sulfanilic acid. Fluorescamine, which acts selectively with primary amines such as sulfanilic acid, is a fluorogenic reagent for the excess amine. The amine consumed, calculated by difference from the total originally present, is directly related to the sodium nitrite content of the sample. Interferences from amino acids and soluble proteins in the meat extract are eliminated by judicious use of a secondary peak in the fluorescence spectra (436 nm excitation, 495 nm fluorescence) combined with measurement at low pH (3.30). The recoveries of sodium nitrite ranged from 83.2 to 99.6% with an average of 93.4% and a standard deviation of ±5.28% for 11 determinations.
Crude Fiber Analysis Without Asbestos
Authors: Holst David O , Gehrke Charles W
Published: February 2020

Hoist reported on new filtration equipment that incorporates a vacuum manifold with an air metering device that provides the operator precise control over the vacuum applied. This equipment, which eliminated asbestos, was used in a study on acid-detergent fiber, cellulose, and lignin determinations. Improved precision and good accuracy were obtained with less time involved for each analysis. One analyst can complete 72 determinations in an 8 hr day. The data were in good agreement with the official AOAC method. Ten collaborative Association of American Feed Control Officials check feed samples (1973) were analyzed independently twice with this method and the results were in good agreement with the reported grand average of the data for the check feed samples. An average range of 0.066% fiber was obtained with an average difference from the reported grand average of +0.0195% fiber. In other experiments, over a 3 week period, 5 forage samples with a fiber content of 3–30% were analyzed singly each week by the reported method and the official final action AOAC method, 7.050–7.054. The average range for the AOAC method was 0.54% and for the crude fiber method without asbestos 0.29%. Important advantages of this method are precision, accuracy, rapidity, and the elimination of asbestos fibers and the hazardg associated with their inhalation.
Collaborative Study of Ion Selective Electrode Method for the Direct Determination of Fluoride in Feeds
Authors: Torma Laszlo
Published: February 2020

A rapid and precise method for the determination of fluoride in feeds employs HC1 extraction of the sample. Acetate buffer and sodium citrate are added to control pH and ionic strength. The amount of fluoride is calculated from a standard curve after measuring the potentials of standard and sample solutions. Eight collaborators participated in the study of the method. Statistical values on 3 pairs of samples were calculated. The standard deviation, precision, coefficient of variation, and bias, respectively, were: Pair 1, 0.005071, 0.001763, 3.09, 0.0034; Pair 2, 0.037122, 0.006475, 1.82, 0.0258; Pair 3, 0.034587, 0.013021, 2.63, 0.0227. The results from the proposed method agreed favorably with the values obtained by using the official final action AOAC method, 7.089. The average and standard deviation, respectively, for individual samples by the proposed method were: Sample 3, 0.049, 0.0029; Sample 4, 0.059, 0.0021; Sample 5, 0.334, 0.0114; Sample 6, 0.341, 0.0101; Sample 7, 0.511, 0.0219; Sample 8, 0.492, 0.0237. By the official method the values were: Sample 3, 0.049, 0.0041; Sample 4, 0.058, 0.0029; Sample 5, 0.334, 0.0055; Sample 6, 0.331, 0.0082; Sample 7, 0.517, 0.0183; Sample 8, 0.499, 0.0175. The ion selective electrode method has been adopted as official first action.
Screening Method for the Detection of Aflatoxins in Mixed Feeds and Other Agricultural Commodities with Subsequent Confirmation and Quantitative Measurement of Aflatoxins in Positive Samples
Authors: Romer Thomas R
Published: February 2020

The method described will detect total aflatoxins (B1, B2, G1, and G2) in mixed feeds, grains, nuts, and fruit products in samples containing as little as 5–15 μg/kg. In addition, the presence of aflatoxins in the positive samples can be confirmed and the toxins can be quantitatively measured, using the same extract as that used for the screening method. In the screening method, aflatoxins are extracted with acetone-water (85+15), and interferences are removed by adding cupric carbonate and ferric chloride gel. The aflatoxins are extracted from the aqueous phase with chloroform and the chloroform extract is washed with a basic aqueous solution. A Velasco-type minicolumn is used to further purify the extract and capture the aflatoxins in a tight band. The screening method has been successfully applied to 24 different agricultural commodities. Quantitative thin layer chromatography was also performed with extracts of each of these commodities. An average recovery of 94% B1, 108% B2, 130% Gl, and 103% G2 was obtained compared to the official final action AOAC method for cottonseed products, 26.048–26.056. Within-laboratory coefficients of variation of 10–15% were obtained for each of the aflatoxins and total aflatoxins in a sample of peanut meal naturally contaminated with 11 μg B1 + 3 μg B2 + 11 μg G1+ 5 μg G2/kg.
Collaborative Study of a Gas-Liquid Chromatographic Method for the Analysis of Propazine
Authors: Hofberg Arthur H , Heinrichs Lee C , Gentry Gene A
Published: February 2020

A gas-liquid chromatographic method for the determination of propazine in wettable powder formulations containing about 80% active ingredient was collaboratively studied, using a matched pair scheme. The propazine was extracted from the powder with chloroform, with dieldrin as an internal standard, and chromatographed on Carbowax 20M, using a flame ionization detector. Two samples were analyzed using peak height measurements with the following results (13 collaborators): 1.2% overall coefficient of variation and 1.2% coefficient of variation for the random error. Statistical evaluation of these factors reveals no evidence of systematic error contribution. The method has been adopted as official first action.
Collaborative Study of the 2,4-Dinitrophenyl Ether Multiresidue Method for Use in Determining Four Carbamate Pesticides in Crops
Authors: Holden Edward R
Published: February 2020

Eight laboratories tested the 2,4-dinitrophenyl ether method for determining carbamate pesticide residues by gas-liquid chromatography. Propoxur, carbofuran, carbanolate, and carbaryl in apples, corn, green beans, and a leafy vegetable (kale, collards, cabbage, or turnip greens) were determined at the fortification levels of 0.1, 0.2, and 0.5 ppm. Average recoveries of propoxur were 87–95% ; carbofuran, 87–100% ; carbanolate, 89–102% ; and carbaryl, 77–92%. No serious background problems were encountered, other than that from field-incurred carbaryl residues in apples. The study revealed the need for certain precautions in determining carbaryl because of its instability in analytical operations. The method has been adopted as official first action.
Mycotoxin Bioassay, Using Bacillus stearothermophilus
Authors: Reiss Jürgen
Published: February 2020

Spores of Bacillus stearothermophilus in standardized spore strips are pretreated with solutions of the mycotoxins aflatoxin Bl, patulin, rubratoxin B, and diacetoxyscirpenol and subsequently incubated in a nutrient solution containing bromocresol purple as pH indicator. After 16.5 hr of incubation the color of the indicator medium inoculated with untreated spore strips of B. stearothermophilus changes from purple to yellow; no color change occurs in the indicator medium inoculated with spore strips treated 15 min with 0.01 μg of any of the 4 mycotoxins/ml during a 60 hr incubation.
Collaborative Study of the Pro-Milk Method for the Determination of Protein in Milk
Authors: Sherbon John W
Published: February 2020

Seven milk samples and 2 standard dye solutions were analyzed for protein content by the Pro-Milk method by 6 collaborating laboratories. Interlaboratory variations, although small, were significant, probably because of extremely good precision. Blind duplicates (2 sets) did not differ from each other. Tests of dilute dye solutions, involving only the colorimeters, showed interlaboratory variation, which indicates the need to carefully calibrate each instrument. The magnitudes of the variations encountered in the milk and dye solution studies were sufficiently small to allow adoption of the Pro-milk method as official first action.
Determination of Heavy Metals in Foods by Anodic Stripping Voltammetry after Sample Decomposition with Sodium and Potassium Nitrate Fusion
Authors: Holak Walter
Published: February 2020

A method is described for the simultaneous determination of several heavy metals in foods. The sample is predigested with nitric acid and decomposed completely by heating with a mixture of sodium and potassium nitrates. The resultant melt containing the metals is then dissolved in dilute nitric acid. After the pH is adjusted to an appropriate value, the metals, such as cadmium, copper, lead, and zinc, are determined by anodic stripping voltammetry. The average recoveries of these metals added to 5 commodities were 98, 98, 96, and 104%, respectively. The relative standard deviations, based on data from analyses of a commodity containing measurable levels of copper, lead, and zinc, were 12.0, 13.0, and 9.7%, respectively.
Residues in Broiler Chick Tissues from Low Level Feedings of Seven Chlorinated Hydrocarbon Insecticides
Authors: Onley John H , Giuffrida Laura , Watts Randall R , Ives N Fred , Storherr Robert W
Published: February 2020

Two chlorinated insecticide feeding studies from 1967–1968, using broiler chicks, have been completed. In Study I, lindane, heptachlor epoxide, dieldrin, endrin, methoxychlor, and DDT were fed in combination at 3 levels: 0.05, 0.15, and 0.45 ppm. Data show that, in fat tissues, heptachlor epoxide attained a level approximately 20 times the respective levels in the feed; dieldrin 15 times; endrin 10 times; p,p’-DDT 9 times; lindane 3 times; and o,p’- DDT less than the feeding levels. Of the DDT metabolites, p,p’-DDE and p,p’-DDD, only p,p’- DDE was significant at 3 times the 0.45 ppm feeding level. Endrin ketone, a metabolite of endrin, reached plateau levels approximately equal to feeding levels. All residue levels in liver tissues were <0.02 ppm. In Study II, technical chlordane was fed singly at the 0.05, 0.15, and 0.45 ppm levels. Results are tabulated for both total chlordane and for 6 identifiable isomers. Total chlordane in fat tissues attained plateau levels 3–5 times the respective feeding levels. Total chlordane levels in liver and breast tissues were all <0.01 ppm.
Total Protein Nitrogen: Evaluation and Comparison of Four Different Methods
Authors: Wall Larry L , Gehrke Charles W , Neuner Terry E , Cathey Robert D , Rexroad Paul R
Published: February 2020

This laboratory has evaluated 2 automated nitrogen methods, the Kjel-Foss and the Missouri-Technicon with block digestor. A modified Kjeldahl method using a low level (40 mg) of CuS04 as a catalyst was also studied. These 3 methods were compared with the official AOAC Kjeldahl method. The experimental set numbered 22 samples, consisting of amino acids, ammonium salts, meals, grains, forages, and American Association of Feed Control Officials check feed samples. This set was analyzed in duplicate 3 independent times by each method. The accuracy and precision values for the 4 methods were excellent, within a very close range, and were equal or superior to the AOAC method. All 4 methods gave average relative standard deviations of <1 %. The 4 methods were compared for rapidity and timeliness of analysis, applicability, cost per sample, and labor and physical requirements to provide those who are responsible for protein nitrogen analysis with a basis for choosing a nitrogen method that would be most suitable for their needs.
Determination of Ancymidol in Formulations and Technical Material
Authors: Frank Richard , Wilson Joe T
Published: February 2020

A method for the determination of the plant growth regulator ancymidol (α-cyclopropyl-α-(4-methoxyphenyl)-5-pyrimidinemethanol) in formulations and technical grade material is presented. Technical grade material or the 4.5% emulsifiable concentrate formulation is dissolved in chloroform and the ancymidol is measured, using a gas-liquid chromatograph equipped with a flame ionization detector. The 0.026% aqueous concentrate formulation is extracted with ethyl acetate and purified by Florisil column chromatography; the ancymidol is measured with a gas chromatograph. The recovery of ancymidol from a Florisil column averaged 100.1%.
Gas Chromatographic Analysis of the Carbon Dioxide Content in Aluminum Hydroxide Gels
Authors: Wilkinson Donald R , Pavlikowski Fred
Published: February 2020

Samples of aluminum hydroxide were mixed with carbon dioxide-free water and agitated until a homogenous mixture resulted. A 400 μl sample was injected into a gas chromatograph equipped with a thermal conductivity detector and a ¼″ copper column packed with Chromosorb 102. The carbon dioxide contained in the aluminum hydroxide gel was separated from oxygen and nitrogen and then measured. The method is suitable for the analysis of gels containing 0.5–10.0% carbon dioxide.
High-Speed Liquid Chromatographic Determination of Biphenyl Residues in Citrus Products
Authors: Reeder Samuel K
Published: February 2020

A simple, direct, and rapid method is given for the analysis of citrus oils for the fungistat biphenyl by high-speed liquid chromatography. The method is extended to orange juice and various “dry flavors” by an extraction procedure. Analytical limits are <1 ppm without need for any cleanup or concentration steps.
Extraction and Cleanup of Organochlorine, Organophosphate, Organonitrogen, and Hydrocarbon Pesticides in Produce for Determination by Gas-Liquid Chromatography
Authors: Luke Milton A , Froberg Jerry E , Masumoto Herbert T
Published: February 2020

A rapid, multiresidue procedure utilizing the minimal cleanup necessary for gas-liquid chromatographic (GLC) analysis is presented. The samples are extracted with acetone and partitioned with methylene chloride-petroleum ether to remove water. The organophosphorus and organonitrogen compounds are then quantitated by GLC, using a KCI thermionic detector. A Florisil cleanup of the extract is performed prior to the determination of organochlorine compounds by a GLC electron capture detector. Carbon-hydrogen compounds such as biphenyl and o-phenylphenol undergo the Florisil cleanup and may also be quantitated by GLC. Quantitative recoveries for 15 organophosphorus, 9 organochlorine, 5 organonitrogen, and 2 hydrocarbon pesticides show the range in polarities of pesticides recovered, from Monitor to biphenyl. The method is simple and fast with a great potential for the analysis of many more compounds.
Gas-Liquid Chromatographic Determination of Resmethrin in Corn, Cornmeal, Flour, and Wheat
Authors: Simonaitis Richard A , Cail R Spencer
Published: February 2020

gas-liquid chromatographic (GLC) method was developed for the determination of residues of resmethrin ((5-benzyl-3-furyl)methyl cistraras-(±)- 2,2-dimethyl-3-(2-methylpropenyl)-cyclopropanecarboxylate) in corn, cornmeal, flour, and wheat. The commodity, fortified with resmethrin, was extracted by tumbling with pentane and transferred to acetonitrile, the fat was partitioned off, and the sample was chromatographed with 3% ethyl acetate in pentane on Florisil containing 0.5% water. The resmethrin residue was determined by GLC with a flame ionization detector. The results were compared with known standards that had undergone the same cleanup procedures. The method was sensitive to concentrations of resmethrin to 0.2 ppm, recoveries averaged 83%, and reproducibility was good.
Filter Paper as a Source of Error in the Determination of Nitrite in Meat
Authors: Nicholas Fiddler Rosemary , Gentilcore Kathleen M
Published: February 2020

Samples of filter paper were found which contain sufficient nitrite to cause significant error in determining the nitrite content of cured meat products by the official AOAC method. Six of 28 boxes of filter paper examined were contaminated with nitrite. All 6 contaminated boxes were the same brand and grade. These samples of filter paper could contribute from 4.6 to 18.4 ppm nitrite to the amount of nitrite analyzed for in meat.
Bacillus subtilis GSY 1057 Assay for Aflatoxin B1 Activation by Rainbow Trout (Salmo gairdneri)
Authors: Schoenhard Grant L , Bishop Paul E , Lee Donald J , Sinnhuber Russell O
Published: February 2020

A rapid and sensitive microbial assay was developed to detect lethal products of anatoxin B1 metabolism by rainbow trout (Salmon gairdneri) Mt. Shasta strain. Bacillus subtilis GSY 1057 (hisA1, uvr-1, metB4), a DNA repair deficient strain, was incubated for 20 min in the 20,000 × g supernate from trout liver homogenates which had been preincubated for 10 min with various levels of aflatoxin B1. Serial dilutions of the incubation mixture were plated in triplicate on tryptose blood agar base plates and colonies were counted after 12 hr at 37°C. One μmole aflatoxin B1 in 3.2 ml incubation mixture reduced viability 60°.
Colorimetric and Gas-Liquid Chromatographic Determination of Atropine-Hyoscyamine and Hyoscine (Scopolamine) in Solanaceous Plants
Authors: Karawya Mohamed S , Abdel-Wahab Samia M , Hifnawy Mohamed S , Ghourab Mohamed G
Published: February 2020

Two colorimetric micromethods are described for the determination of atropine-hyoscyamine and hyoscine (scopolamine), using p-dimethylaminobenzaldehyde and citric acid-acetic anhydride as the color reagents. These methods are sensitive to 60-1200 and 10-360 μg alkaloid/10 ml. The colorimetric methods were also successfully applied after a preliminary thin layer chromatographic separation of the alkaloids. A gasliquid chromatographic procedure was also developed, which yielded comparable results with the colorimetric methods.
Preservatives in Cosmetics: Partition Chromatography and Ultraviolet Spectrophotometry
Authors: Sheppard E Patricia , Wilson Clifton H
Published: February 2020

Separation by partition chromatography and determination by ultraviolet (UV) spectrophotometry have been applied to the analysis of 16 preservative chemicals used in cosmetic products. The method, adapted from the official first action method for hexachlorophene, 35.023–35.027, has broad applicability for the determination of preservatives in cosmetics. Among the chemical classes investigated, phenols, parabens, biphenyls, carbanilides, and salicylanilides are represented. The partition chromatographic technique does not separate 3,4’,5-tribromosalicylanilide (TBS) from hexachlorophene or Irgasan DP 300. However, the UV determination of these compounds was accomplished by utilizing an absorption maximum of TBS which does not coincide with that of the other 2 preservatives. Recoveries averaged 97% for all the compounds studied.
Quantitative Determination of Coumestrol in Dried Alfalfa and Alfalfa Leaf Protein Concentrates Containing Chlorophyll
Authors: Knuckles Benny E , Miller Raymond E , Bickoff E M
Published: February 2020

An improved analytical method for the determination of coumestrol in dried alfalfa and leaf protein concentrates is described. In this method, chlorophyll is removed from an alcohol extract prior to the paper chromatographic-fluorometric measurement of coumestrol. Ninety-eight per cent of the coumestrol added to alfalfa leaf protein concentrates is recovered by this method. This improved method gives replicate values with lower standard deviations and coefficients of variation than the literature method.
Spectral Compilation of Dyes, Intermediates, and Other Reaction Products Structurally Related to FD&C Yellow No. 6
Authors: Bailey John E , Calvey Robert J
Published: February 2020

Spectral data are presented for 10 intermediates, 25 dyes, and 2 side-reaction products that are related to FD&C Yellow No. 6. Also included are purification procedures for the intermediates and side-reaction products and methods of synthesis and purification for the corresponding dyes. Spectral data consist of acid, base, and neutral curves in the visible and ultraviolet regions. Also included are infrared spectra. Molar extinction coefficients are calculated for the visible and ultraviolet spectra.
Pyrolysis-Gas Chromatographic Analysis of Black Paints
Authors: Schultz Blair W , Perros Theodore P
Published: February 2020

Samples of 79 black paints from 27 manufacturers in the United States were examined to determine the extent to which paints can be distinguished by pyrolysis-gas chromatography. Evaluation by a Carbowax column showed some differences among paints from different manufacturers and among batches of paints from the same manufacturer. However, it was not possible to conclude that paints with identical chromatograms had a common origin.
Rapid Determination of Fat in Meat and Meat Products by Foss-let Solvent Extraction and Density Measurement
Authors: Pettinati Julio D , Swift Clifton E
Published: February 2020

The commercially available Foss-let fat analyzer was evaluated for the determination of fat in meat and meat products by comparison with AOAC method 24.005(a). With the Foss-let procedure, mechanical and instrumental equipment is used to determine fat in 7–10 min. A sample is extracted with tetrachloroethylene in a mechanical orbital shaker for 2 min and the specific gravity of the extract is measured in a magnetic float cell controlled by a digital potentiometer. During extraction, anhydrous calcium sulfate absorbs moisture droplets originating from the sample. The variations of comparative determinations on 67 meat samples containing 1.1–95.4% fat and 17 frankfurter samples containing 17.3–37.3% fat were analyzed statistically by grouping the data according to meat type (beef or pork) or frankfurters and into 6 ranges of fat content, and by treating the entire set of data. Error analysis of the differences and standard deviation of each grouping of paired determinations by the Fosslet and AOAC methods indicated that meat type and fat content >7.5% were not significant (P = 0.05) sources of variation as determined by t-tests on the statistics from the blocks of data. Determinations on samples containing ≤7.5% fat were consistently low and an additive correction of 0.25% was indicated. From the overall results, the accuracy and precision of the method were characterized as follows: the mean Foss-let method determination was high by 0.08% fat relative to that by the AOAC method; repeatability of ± 0.31% fat between duplicate determinations compared favorably with ±0.38% obtained with the AOAC method; and precision between paired determinations by the 2 methods was ±0.44%. Both a t-test for significance (P = 0.05) and the linear regression of the 84 comparative determinations indicated that the Foss-let method was equivalent to the AOAC method for determining fat.
Formaldehyde Titration Method for the Determination of Ammoniacal Nitrogen in Phosphate Fertilizers
Authors: R Anjaneyulu T S
Published: February 2020

The present formaldehyde titration method, applicable to ammonium nitrate and ammonium sulfate samples, has been improved for the analysis of ammoniacal nitrogen in phosphate fertilizers. Samples of 14-35-14 and 28-28-0 fertilizers are analyzed by the improved formaldehyde titration method and the results are compared with the Kjeldahl distillation method. The formaldehyde method is applicable for 14-35-14 and 28-28-0 fertilizer samples, provided the initial pH of the sample solution is adjusted to pH 7.7 prior to the addition of neutral formaldehyde solution. For the analysis of samples of phosphate fertilizers of the same grade, the improved formaldehyde method offers a distinct advantage over the Kjeldahl method, and can be used for the rapid analysis of process control samples.
Survey of U.S. Wheat for Ochratoxin and Aflatoxin
Authors: Shotwell Odette L , Goulden Marion L , Hesseltine Clifford W
Published: February 2020

A total of 291 hard red winter wheat samples, 286 hard red spring wheat samples, and 271 soft red winter wheat samples were analyzed for the presence of ochratoxin and aflatoxin. Samples in all grades came from those collected during crop years 1970–1973 for grade determinations by the Agricultural Marketing Service, U.S. Department of Agriculture. Sensitivity limits of the analytical method as carried out were 1–3 ppb aflatoxin B1 and 15–30 ppb ochratoxin A. No aflatoxin was detected in any sample. Three samples of hard red winter wheat (Grades U.S. No. 4 and 5 and Sample Grade) contained ochratoxin A (trace, 35, and 25 ppb, respectively). Eight of the hard red spring wheats contained ochratoxin A (15-115 ppb); these were in Grades U.S. No. 4 and 5 and Sample Grade.
Iodometric Determination of the Peroxide Value of Edible Oils
Authors: Gutfinger Tamar , Peled Micha , Letan Arieh
Published: February 2020

The results of peroxide value determinations in soybean oils depend on the temperature at which the experiments were carried out. The effect of temperature on the values obtained was more pronounced in oils which contained higher amounts of peroxides. When the determinations were carried out in the presence of air, the peroxide values of fresh and oxidized oils to which Fe3+ (20 ppm) had been added were considerably higher than those which were obtained for the same oils without added Fe3+. In the presence of nitrogen, lower values than expected were obtained for oxidized oils with added Fe3+, whereas values which were obtained for unoxidized oils, with or without Fe3+, were similar.
Determination of Methyl Mercury in Fish by Flameless Atomic Absorption Spectroscopy and Comparison with an Acid Digestion Method for Total Mercury
Authors: Kacprzak Jurgen L , Chvojka Ramon
Published: February 2020

A method for the concurrent determination of methyl mercury and inorganic mercury by flameless atomic absorption spectroscopy (AAS) is described. Fifty-seven samples of juvenile black marlin fish were analyzed for inorganic and methyl mercury, and total mercury was calculated by addition of the 2 values. The sensitivity of the method was estimated to be 0.029 μg for inorganic mercury and 0.033 μg for methyl mercury. The detection limit of the method was about 0.02 μg inorganic mercury or methyl mercury and the error of the method was found not to exceed 10% for samples giving about 10% deflection on the absorbance scale. Samples from the same fish were analyzed by a commonly accepted flameless AAS method for the determination of total mercury. When the results for total mercury from the 2 methods were statistically compared, using a paired t-test, the difference between the results obtained by the 2 methods was found to be insignificant at the 95% confidence level.
Rapid Micro Screening Method for Direct Available P2O5 in Fertilizers
Authors: Thorpe Virginia A
Published: February 2020

A rapid micro screening technique is presented for determining direct available P2O5 in fertilizers containing no organic or condensed phosphates. This modification of the macro color method uses microliter pipets, automatic dispensor pipets, and a double-beam spectrophotometer equipped with a sipper system and printer. The method combines speed and simplicity with accuracy and precision and does not require specialized automated equipment.
Confirmation of Vinyl Chloride in Foods by Conversion to 1-Chloro-1,2-dibromoethane
Authors: Williams David T
Published: February 2020

A semiquantitative method has been developed for the confirmation of vinyl chloride (VC) in foodstuffs. The VC was brominated to give 1-chloro-1,2-dibromoethane which was analyzed by gas-liquid chromatography, using an electron capture detector. The yield of 1-chloro-1,2-dibromoethane varied between 40 and 55%, which permitted a lower limit of confirmation of VC of 15 ppb for vinegar and sherry and 50 ppb for peanut oil.
Gas-Liquid Chromatographic Determination of Nikethamide in Injectable Preparations
Authors: Newton John M
Published: February 2020

A gas-liquid chromatographic (GLC) method, using a 4% XE-60 on 80-100 mesh Gas-Chrom Q column, a flame ionization detector, and anthracene as the internal standard, has been developed for the direct determination of nikethamide. Eight collaborators analyzed 4 samples, using methanol as the solvent; the coefficients of variation obtained ranged from 1.19 to 3.20%. In a limited study with acetone as the solvent, the coefficients of variation ranged from 0.59 to 1.96%. The GLC method with acetone as a solvent has been adopted as official first action.
Gas-Liquid Chromatographic Determination of 3,6-Dichloropicolinic Acid in Soils
Authors: Pik Andrew J , Hodgson Gordon W
Published: February 2020

A gas-liquid chromatographic (GLC) method has been developed for the determination of the experimental herbicide 3,6-dichloropicolinic acid (Dowco 290) in soils. The method involves extraction of 1 g soil samples with 1N NaCl at approximately pH 7, methylation with diazomethane utilizing a microgenerator, and detection by electron capture GLC. Interferences are small, so that a cleanup step is not necessary even at the 6 ppb level. The procedure is rapid, requiring only 45 min/sample. Recoveries range from 84 to 94% at the 6–1000 ppb level with a minimum detectable limit of 6 ppb. Standard deviations for the percentage recovery values vary from 10.9 to 2.3 for the tested range of 6.7–670 ppb, respectively.
Excretion of Hydroxylated Polychlorinated Biphenyl Metabolites in Cows’ Milk
Authors: Gardner Albert M , Righter Herbert F , Roach John A G
Published: February 2020

Four lactating Holstein cows were each given a single oral dose of either 0,5 g 2,5,2′,5′-tetrachlorobiphenyl, 0.5 g 2,5,2′,4′,5′-pentachlorobiphenyl, 1.5 g Aroclor 1242, or 1.5 g Aroclor 1254 in gelatin capsules. Milk samples were collected twice daily at the am and pm milkings and were analyzed for polychlorinated biphenyl (PCB) metabolites and PCBs. Excretion of metabolites in the milk paralleled excretion of the parent PCBs, with maximum amounts eliminated 1 day after dosing. Less than 0.06% of the initial doses of the 2 single components appeared as metabolites in milk over a period of 10 days. Most of the metabolites occurred as conjugates. Only the 4-hydroxy metabolites were found in the milk of cows given single components. Milk samples from cows given Aroclor 1242 or Aroclor 1254 contained 10 and 4 monohydroxy metabolites, respectively. Using the same methodology, no monohydroxy metabolites were detected in whole milk samples from herds accidentally contaminated with a polybrominated biphenyl mixture.
Survey of Food Products for Volatile N-Nitrosamines
Authors: Havery Donald C , Kline David A , Miletta Elaine M , Joe Frank L , Fazio Thomas
Published: February 2020

A variety of food products containing nitrite were analyzed for 14 volatile N-nitrosamines by using a method demonstrated to be sensitive to 10 ppb. A total of 121 food samples were screened for volatile N-nitrosamine content. N-Nitrosopyrrolidine was confirmed in fried bacon at levels up to 139 ppb. N-Dimethylnitrosamine, N-nitrosopyrrolidine, and N-nitrosopiperidine were also confirmed in spice-cure mixtures at levels ranging from 50 to 2000 ppb.
Determination of Bergapten in Fragrance Preparations by Thin Layer Chromatography and Spectrophotofluorometry
Authors: Wisneski Harris H
Published: February 2020

A method has been developed for the determination of bergapten (5-methoxypsoralen), a known phototoxin, in perfumes, colognes, and toilet waters. The bergapten and other lactonic compounds were first isolated from the sample by a series of extractions. The extract containing the bergapten was diluted to a known volume and an aliquot was spotted on a thin layer chromatographic (TLC) plate coated with silica gel G. After 2-dimensional development with hexane - carbon tetrachloride - tert - butylamine (180 + 12 + 9) and hexane-toluene-ethyl acetate-acetic acid (100+10+15+0.5), the TLC plate was dried and the emitted fluorescence of bergapten was measured, using a spectrophotofluorometer equipped with a TLC accessory and coupled to an automatic digital integrator. The amount of bergapten was determined by comparing its peak area to those of bergapten standards. The average recovery for levels of 0.001, 0.005, and 0.01% bergapten was 88%.
Determination of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Commercial Pentachlorophenols by Combined Gas Chromatography-Mass Spectrometry
Authors: Buser Hans-Rudolf , Bosshardt Hans Paul
Published: February 2020

Samples of commercial pentachlorophenol (PCP) and its sodium salt (PCP-Na) were examined for the presence of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), using a rapid, highly specific method of analysis. Phenolic compounds are removed by alkaline extraction, and the neutral components are fractionated on an alumina minicolumn. After gas chromatographic separation, individual PCDDs and PCDFs are detected by mass fragmentography and their presence is confirmed by complete mass spectral analysis. While some samples had only low amounts of PCDDs and PCDFs, others contained much higher amounts of these components. PCP-Na samples showed the unexpected presence of a tetrachlorodibenzo-p-dioxin. Re-analysis of PCP and PCP-Na samples with high PCDD contents on a high-resolution glass capillary column showed the presence of 3 hexa- and the 2 heptachlorodibenzo-p-dioxins with nearly constant isomeric ratios.
Determination of Arsenic and Selenium in Foods By Electroanalytical Techniques
Authors: Holak Walter
Published: February 2020

Arsenic and selenium are determined in foods by differential pulse polarography and cathodic stripping voltammetry. The sample is digested with nitric acid and magnesium nitrate and then dissolved in dilute hydrochloric acid. An aliquot is removed, the arsenic is chemically reduced to the trivalent state, and interferences are removed by ion exchange before polarography. Selenium is determined in a second aliquot by cathodic stripping voltammetry. Recoveries for both elements in several foods were from 90 to 110%. The relative standard deviations for arsenic at 5 ppm and selenium at 0.48 ppm were 5.8 and 7.3%, respectively.
Analytical Variation When Proportions of Sampled Units Contain the Active Agent
Authors: Kwolek William F , Lillehoj Eivind B
Published: February 2020

When a product consisting of discrete units is sampled, the number of units to be selected depends on p, the proportion of units containing an active agent. If the sample is ground, the problem of subsample size is complicated when only a proportion, g, of the subparticles generated from each unit containing the active agent is active. Procedures have been devised for determining sample size, subsample size, and fineness of grind for wide ranges of p and g. The expected precision of the analytical result is influenced by both sampling variation and analytical variation.
Chemical Confirmation of Diethylstilbestrol Residues in Beef Livers
Authors: Ryan John Joseph , Pilon Jean-Claude
Published: February 2020

A simple chemical technique was developed to confirm the presence of diethylstilbestrol (DES) residues in beef tissues at 2 ppb. The DES-trifluoroacetate (TFA) from the previously published method is hydrolyzed in water-methanol at 55°C for 20 min to free DES which is then extracted into benzene. Trimethylamine and a small amount of heptafluorobutyric (HFB) anhydride are added to effect the smooth conversion of DES to its di-HFB at either room temperature or 60°C. DES-HFB is determined by gas-liquid chromatography with electron capture detection on a 6′ × 4 mm id column of 3% OV-210 at 190°C. This procedure yields 2 peaks for DES-HFB (retention times 2.7 and 4.8 min for the cis and trans, respectively) which are resolved from the 2 DES-TFA peaks (retention times 2.3 and 3.3 min for cis and trans, respectively). The sensitivity of detection of DES-HFB is increased by a factor of 4–5 over that for DES-TFA. This chemical technique was successfully applied to purified extracts of beef liver fortified with DES at 2–10 ppb with recoveries from 60 to 110%.