bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collaborative Study of the Elemental Analysis of Plant Tissue by Direct Reading Emission Spectroscopy
Authors: Jones J Benton 
Published: February 2020

Abstract
Eleven laboratories collaboratively studied the use of direct reading emission spectroscopy, with the solution rotating disk technique of excitation for the elemental analysis of plant tissues: aluminum, barium, boron, calcium, copper, iron, magnesium, manganese, molybdenum, phosphorus, potassium, sodium, strontium, and zinc in alfalfa, citrus leaves, orchard leaves, pine needles, and tomato leaves. Since not all direct reading emission spectrographs are alike in all features, provisions were made to accommodate these differences relating to sample preparation, selection of the internal standard, and method of sample excitation. The sample is dry ashed and the ash is dissolved in an acidic buffer solution. Coefficients of variation obtained in the collaborative study ranged from 3 to 50%. For most plant tissue samples and elements, the value is less than 20%. The results obtained with direct readers are generally better than those obtained on photographic instruments and comparable to those obtained by atomic absorption spectroscopy. Direct reading emission spectroscopy is rapid, providing 14 elemental analyses in generally less than 1 min for a prepared sample. The method has been adopted as official first action.
Microdetermination of Bioethanomethrin
Authors: George Donald A , Mcdonough Leslie M 
Published: February 2020

Abstract
A microanalytical method was developed for the determination of the experimental synthetic pyrethroid insecticide Bioethanomethrin ((5- benzyl-3-furyl) methyl trans-(+)-3-( cyclopentylidenemethyl)-2,2 -dimethylcyclopropanecarboxylate). After saponification, trichloroacetyl chloride is used to form an ester from the alcohol moiety, and trichloroethanol is used to form an ester from the acid moiety. Infrared and mass spectral data support the expected structures of the derivatives formed. Nanogram sensitivity is realized by utilizing a gas chromatograph with an electron capture detector.
Automated Method for the Determination of Niacin and Niacinamide in Cereal Products: Collaborative Study
Authors: Gross Anthony F 
Published: February 2020

Abstract
In a collaborative study, an automated method for the determination of niacin and niacinamide in cereal products was compared with the official final action microbiological (43.121–43.125) and chemical (43.044–43.046) methods. Ten samples of cereal products, including enriched flour, yeast-leavened baked products, fortified breakfast cereals, and baked pet food products, were submitted to 14 laboratories. Nine laboratories reported values by the automated method, 6 reported values by the microbiological method, and 7 reported values by the chemical method. The results from the microbiological method were not subjected to analysis of variance because of the unusually large between-laboratory variation. The between-laboratory coefficients of variation for the automated and chemical methods were 10.90 and 10.18%, on the basis of results from 7 and 4 laboratories, respectively. There was no significant (p&gt;0.05) difference between methods when results from the 4 laboratories who used both methods were compared. The automated chemical method has been adopted as official first action.
Spectroscopic Properties of the Methyl Esters of Chlorophenoxy Acid Herbicides
Authors: Van Peteghem Carlos H , Heyndrickx Aubin M 
Published: February 2020

Abstract
The mass and infrared spectra of the methyl esters of 9 chlorophenoxy acid herbicides are presented. Ultraviolet data are discussed and proton magnetic resonance spectra are tabulated. Because of the sensitivity of the technique, the mass spectra are most useful for the identification of those compounds in residues, especially by combined gas chromatographymass spectrometry. The pure herbicides used for the recording of the spectra were obtained by synthesis and recrystallization.
Thin Layer Chromatographic Detection and Indirect Gas Chromatographic Determination of Three Carbamate Pesticides
Authors: Ernst George F , Röder Saskia J , Tjan Gwan H , Jansen John T A 
Published: February 2020

Abstract
Carbamate pesticide residues are extracted from vegetables and fruits with methylene chloride. The extracts are spotted on silica gel plates and the pesticides are detected by an enzymatic inhibition technique. For quantitative determination, aliquots of the methylene chloride extracts are evaporated to dryness in a rotary evaporator. After the residues are dissolved in ethanol, 0.5N NaOH is added in the hydrolysis step. To remove a number of possible interferences the hydrolyzed phenols are steamdistilled and treated with l-fluoro-2, t-dinitrobenzene and/or 4-chloro-α,α,α-trifluoro-3,5-dinitrotoluene to form the ether derivatives. Efficiency in the conversion of the phenolic moieties to the phenyl ethers is about 100%. The resulting electron-capturing derivatives enable the carbamate pesticides to be detected in vegetables and fruits at the 0.05 ppm level. Recoveries of 90–94% were obtained from vegetables and fruits fortified with 0.5–2.0 ppm carbaryl, Mesurol, and propoxur.
Determination of Methylene Chloride, Ethylene Dichloride, and Trichloroethylene as Solvent Residues in Spice Oleoresins, Using Vacuum Distillation and Electron Capture Gas Chromatography
Authors: Page B Denis , Kennedy Barry P C 
Published: February 2020

Abstract
A quantitative gas chromatographic (GC) method is described for the determination of residual methylene chloride, ethylene dichloride, and trichloroethylene in spice oleoresins. The proposed method involves vacuum distillation in a closed system with toluene as a carrier solvent. Quantitation by electron capture GC on Porapak Q is facilitated by water extraction and by the addition of trans-l,2-dichloroethylene as an internal standard. Recoveries from oleoresins spiked at 30, 15, and 6 ppm ranged from 93 to 102%. To assess the possibility of interference from spice volatiles, the procedure was applied to 17 different spice oleoresins from 3 different manufacturers. No interferences were found, but methylene chloride levels up to 83 ppm and ethylene dichloride levels up to 23 ppm were detected. Trichloroethylene was not detected in any of the oleoresins.
Effect of Carbohydrates on the USP Test for Readily Carbonizable Substances
Authors: Dokladalova Jarmila , Upton Ronald P 
Published: February 2020

Abstract
Carbohydrates, when present as impurities in certain types of samples, have a strong effect on the USP test for readily carbonizable substances. In some instances as little as 50 µg carbohydrate, e.g., glucose, drastically increases the result of the test. The reaction mechanism is discussed and the carbonization potential of individual carbohydrates is evaluated.
Improved Cleanup Technique for the Estimation of Endosulfan and Endrin Residues
Authors: Kathpal Trilochan S , Dewan Ram S 
Published: February 2020

Abstract
An improved cleanup technique has been developed for the extraction of endosulfan and endrin from crops. The technique involves the use of Nuchar C-190N as adsorbent and a mixture of n-hexane and acetone (4+1) as the eluting solvent. The mean percentage recoveries of endosulfan (I and II) and endrin from plant tissue extracts fortified at levels of 0.5–2.0 ppm varied from 86 to 102 and 97 to 100, respectively.
A Practical Method for the Comparison of Mineral Wool Insulations in the Forensic Laboratory
Authors: Miller Elmer T 
Published: February 2020

Abstract
The comparison of glass wool, slag wool, and rock wool insulations by means of refractive index and dispersion is practical and effective. The material is annealed at &gt;1150°–1200°F; this process burns off the resinous coating and leaves the fibers and slugs suitable for microscopic study, solubility tests, fluorescence observations, and refractive index and dispersion measurements. Refractive index and dispersion values for the annealed fibers are obtained by the Emmons double variation method, using a hot stage, a monochromator, and a phase microscope. In a study of 34 mineral wool insulations, a range of refractive indices was obtained that was 7 times the range exhibited by window glasses. In one case the value of the method was proven when insulations from 3 sources were each matched with fibers and slugs from a suspect’s clothes.
Infrared Identification Test for Scopolamine as the Hydrobromide
Authors: Brannon Wilson L , Levine Joseph 
Published: February 2020

Abstract
The method of preparation of scopolamine hydrobromide affects the infrared (IR) spectrum of the product. A column chromatographic procedure is used to both isolate the drug from tablets and injections and form the hydrobromide salt. This yields reproducible IR spectra and thus constitutes an identity test for scopolamine hydrobromide.
Colorimetric Determination of Diazepam in Pharmaceutical Preparations
Authors: Baggi Tulsidas R , Mahajan Surinder N , Rao Griddaluru Ramana 
Published: February 2020

Abstract
A colorimetric method is presented for the estimation of diazepam as the pure drug and in formulations. Diazepam is hydrolyzcd with 6N HC1 to 2-methyIamino-5-chlorobenzophenone, which is extracted with chloroform to give a yellow solution whose absorbance is measured at 410 nm against a solvent blank. The color obeys Beer's law in the concentration range of 0–30 μg/ml. In 5 determinations, recovery was 99.0±1.9%. The method is applicable to pure diazepam and its formulations for oral and parenteral use. No interferences were observed from pyridoxine hydrochloride and commonly used preservatives, vehicles, and colors.
Nitrate Determination in Baby Food, Using the Nitrate Ion Selective Electrode
Authors: Pfeiffer Sandra L , Smith Jean 
Published: February 2020

Abstract
The nitrate electrode has been utilized in the determination of nitrate content in food products. The AOAC xylenol method was employed for comparative results. A reasonable correlation (r = 0.91) was found between the 2 methods in the analysis of 49 samples containing 30–350 ppm nitrate. At the average nitrate content (100 ppm) of these foods, the standard error was 4.3 ppm. The electrode responds directly to the ionic activity of the nitrate ion. It has a linear concentration range of 1–6000 ppm nitrate and can be used over a wide pH range. The electrode does respond to some extent to anions other than nitrate, and some interferences do occur. These interferences are easily controlled by the use of cation exchange resins. The Corning known addition (spiking) method is used on all samples to insure correct electrode response in solutions containing variable background ionic composition. The electrode has the advantage of simplicity, speed, reproducibility, and accuracy. Work time saved using the electrode as opposed to the xylenol method is about 7 hr for the analysis of 20 samples. Error, and the need for repeating analysis, is much less frequent.
Spectrophotometric Determination of Boron in Boronated Fertilizers
Authors: Neuner Terry E , Pickett Edward E , Gehrke Charles W 
Published: February 2020

Abstract
Acid-soluble boron in fertilizers is complexed in acid solution with 2-ethyl-l,3-hexanediol and extracted into methyl isobutyl ketone. The extract is nebulized into an air-hydrogen flame and the intensity of emission of the BO2 molecule is measured at 518 inn. The method is convenient and inexpensive and provides detection limits of 0.1 ppm. The method was tested on 6 fertilizer samples with the relative standard deviation varying from 5.6% on a 0.053% (w/w) sample to 2.6% on a 7.81% (w/w) sample. The recovery of added boron ranged from 94.5 to 104.2% with an average recovery of 99.7%.
Automated Flame Photometric Determination of K2O in Fertilizers
Authors: Neuner Terry E , Pickett Edward E , Gehrke Charles W , Wippler John F 
Published: February 2020

Abstract
The well known chemical interference of phosphorus on the emission of potassium in cool flames was verified and found to cause small but significant error in using the official final action AOAC method of analysis. This effect can be greatly reduced by incorporating the use of lanthanum along with the internal standard, lithium. Lanthanum has been shown to reduce the chemical interference of phosphorus by chemical bonding without affecting potassium or lithium emission characteristics. The resulting manifold can be used to analyze samples at the rate of 6 0 / h r with no significant interference.
Evaluation of the Babcock Method for the Determination of Milk Fat
Authors: Mckinley Myron R , Arnold Richard E , Rosenbury John B , Born Earl C , Dunham Chapman E , Park Douglas L 
Published: February 2020

Abstract
The Babcock test for fat in milk was evaluated to study the effects of variables such as glassware calibration, sample preparation, sample composition, reagents, tempering conditions, procedural variations, and analyst. Certain test bottles yielded significantly different results; however, there was little indication of pipet variation. Analysis of the various techniques for tempering and mixing indicated that samples tempered at 68°F (20°C), containing an airspace of approximately 25% of the total container, and mixed by inversion 5–10 times or poured from one container to another gave the most consistent results. Sample composition did not affect results, provided all milk-solids-notfat were digested by the sulfuric acid. A pipet draining time of 10 sec followed by blowing out the pipet was sufficient to yield reproducible results. Differences between lots of sulfuric acid affected results. Results were 0.027% less when the final test tempering was 130°F (54.5°C) compared to 140°F (60°C); however, a final tempering for a minimum of 3 min gave satisfactory results. Variations in reading results between individual analysts were negligible. The Babcock method for fat in milk, modified to include the optimum parameters as determined in this study, was subjected to a collaborative study. Nine laboratories analyzed 10 samples in duplicate. Statistical analysis of collaborative data indicates a significant difference between laboratories (p &lt;0.01 ). The repeatability standard deviation of the method is 0.0183%. The reproducibility standard deviation is 0.0407%. The repeatability and reproducibility coefficients of variation are 0.53 and 1.17%, respectively. On the basis of the collaborative results, the following changes have been incorporated into the official final action method: specifications for the reading light; sample draining time; tempering temperature of the acid; tempering procedure for reading the test bottle.
Determination of Polybrominated Biphenyl Residues in Dairy Products
Authors: Fehringer Norbert V 
Published: February 2020

Abstract
A method for the determination of polybrominated biphenyls (PBBs) in dairy products is described. Fat is extracted from the products by the official AOAC method. The PBB residues are separated from the fatty material by gel permeation chromatography prior to gas-liquid chromatographic (GLC) quantitation. An additional cleanup using petroleum ether elution through a miniature Florisil column is necessary for thin layer chromatographic (TLC) confirmation. Recoveries of PBBs from samples fortified at levels from 0.1 to 0.5 ppm ranged from 94 to 104% with an average of 99%. GLC sensitivity permits the estimation of PBB residue levels as low as 0.007 ppm. Routine TLC confirmation is limited by sensitivity to ≥0.2 ppm.
Radioassay of Chromic Phosphate 32P Suspension by Cerenkov Counting
Authors: Heitzman Martin W , Ford Leonard A 
Published: February 2020

Abstract
A simple and precise method is presented for the radioassay of chromic phosphate 32P suspension by Cerenkov counting. An aliquot is weighed, dissolved, diluted, and then counted directly in a conventional liquid scintillation counter. The internal standard technique is used to provide color quench correction. This method is particularly useful for high specific activity samples. The standard deviation for the analysis of 3 aliquots, each determined in triplicate, was 1.9%.
Determination of Fluoride in Vegetation: A Comparative Study of Four Sample Preparation Methods
Authors: Van Den Heede Marc A , Heyndrickx Aubin M , Van Peteghem Carlos H , Van Zele Wilfried A 
Published: February 2020

Abstract
Four sample preparation methods (dilute acid digestion, concentrated acid digestion, alkali fusion, and low temperature ashing) for the determination of fluoride in vegetation are compared. A fluoride ion selective electrode is used for the final quantitative measurements. Ionic strength and pH are maintained by a concentrated citrate buffer. The highest sensitivity and reproducibility are obtained by low temperature ashing of the dry sample. Several vegetables, grown in the neighborhood of a glaze factory, were simultaneously analyzed by 2 of the methods, the dilute acid digestion and the low temperature ashing procedures. The higher fluoride content found with the latter technique is attributed to the complete mineralization of the sample.
Gas-Liquid Chromatographic Determination of Naled in Pesticide Formulations
Authors: Carlstrom A Aner 
Published: February 2020

Abstract
Dusts, emulsions, concentrates, and technical material covering a wide range (1%92%) of naled were diluted or extracted with chloroform. Dibutyl phthalate was added to sample extracts as an internal standard before gas-liquid chromatographic (GLC) injection. Twelve column packings covering the entire polarity scale were tested, and 3% XE-60 was chosen, based on the best resolution for a difficult-to-separate low volume concentrate. Response is linear from 1 to 50 mg naled/ml and the coefficient of variation for the GLC step is 0.81%. Of 29 other active ingredients which have been formulated with naled, diazinon and 1 isomer of BHC elute with naled, while dicrotophos elutes with the internal standard.
Colorimetric and Volumetric Assays of Colchicine in Galenicals and in Pharmaceutical Preparations
Authors: Karawya Mohamed S , Diab Aly M 
Published: February 2020

Abstract
In the method described the amide group in the colchicine molecule is reduced with lithium aluminum hydride to the corresponding secondary amine. The latter is extracted with chloroform and then determined either colorimetrically by the copper dithiocarbamate reaction or volumetrically by dissolving in acid and titrating with sodium hydroxide or perchloric acid. The results were comparable with those obtained by the Egyptian Pharmacopoeia spectrophotometry method.
Chromatographic Methods for the Analysis of Hexachlorobenzene and Possible Metabolites in Monkey Fecal Samples
Authors: H Yang Raymond S , Coulston Frederick , Golberg Leon 
Published: February 2020

Abstract
The separation and identification of hexachlorobenzene (HCB), pentachlorobenzene (QCB), and pentachlorophenol (PCP) by thin layer, high-pressure liquid, and gas chromatography are reported. Satisfactory results were obtained with reverse phase thin layer and highpressure liquid chromatography. The 2 gas chromatographic columns tested gave adequate separation of HCB and QCB. A PCP methylation process using dimethyl sulfate was attempted. Procedures are presented for extraction, cleanup, separation, and identification of HCB and possible metabolites from feces of a rhesus monkey treated with 14C-HCB. Recovery of radioactivity in excess of 96% was attained in extracts from feces by these methods. Preliminary evidence suggests the formation of PCP and possibly other polar metabolites from HCB in the rhesus monkey.
Gas-Liquid Chromatographic Determination of Vinyl Chloride in Vinyl Chloride Polymers, Food-Simulating Solvents, and Other Samples
Authors: Breder Charles V , Dennison J Lawrence , Brown Margaret E 
Published: February 2020

Abstract
The determination of vinyl chloride (VC) in polyvinyl chloride (PVC), vegetable oils, foodsimulating solvents, mouthwashes, and blood anticoagulant solutions by gas-liquid chromatography is described. PVC polymers are dissolved in either tetrahydrofuran or dimethyl acetamide. Vegetable oils are diluted with an equal volume of tetrahydrofuran. The resulting solutions are injected into a gas-liquid chromatograph equipped with a flame ionization detector. Mouthwashes, blood anticoagulant solutions, and 3 food-simulating solvents, 3% acetic acid, 50% ethanol, and heptane, are analyzed by direct injection into a chromatograph. Sensitivities are such that 0.05 ppm VC in solution or 1 ppm VC in PVC can be quantitated.
A Screening Method for Determining Nitrofuran Drug Residues in Animal Tissues
Authors: Ryan John J , Lee Young C , Dupont Jo A , Charbonneau Claudette F 
Published: February 2020

Abstract
A method was developed for measuring low levels of total nitrofurans in animal tissues and milk. The antimicrobial nitrofurans (5 or more products) used in agriculture are extracted from tissue with aqueous acid in the presence of ethyl acetate. After centrifugation and evaporation, the organic residue is washed with hexane and the nitrofurans are hydrolyzed to 5-nitrofuraldehyde in aqueous acid at 70°C. The hydrolysis product is extracted with benzene and measured by gas-liquid chromatography with electron capture detection. Recoveries of nitrofurazone and furazolidone from fortified poultry and swine tissues at the levels of 0.5 and 0.1 ppm are 75 and 65%, respectively. This procedure can be used to detect the total nitrofuran content of as little as 10 ppb muscle tissues and milk, 100 ppb liver, and 50 ppb fat with no interference from related veterinary nitrodrugs.
Collaborative Study of a Spectrophotometric Method for Determining Maleic Hydrazide Residues in Tobacco and Vegetables
Authors: Ihnat Milan , Thompson Brian 
Published: February 2020

Abstract
A distillation-spectrophotometric method for the determination of maleic hydrazide residues in tobacco and vegetables reported previously was studied collaboratively. Ten laboratories submitted analytical results on 10 samples containing residues resulting either from field treatment or laboratory fortification. The samples were estimated to contain from 0.99 to 16.36 μg maleic hydrazide/0.5 g sample analyzed. The coefficients of variation based on precision standard deviation ranged from 57.7% for the lowest residue content to 32.4% for the highest. The corresponding coefficients of variation based on overall standard deviations were estimated to be at least one-fifth larger. Strong evidence of systematic laboratory differences was found (F-test, significant at 0.1%). Apparent recoveries of 10.0 fifl maleic hydrazide added to 0.5 g fluecured tobacco and potato were 97.3 and 89.7%, respectively. Apparent recoveries of 16.0 and 16.5 μg added to 0.5 g green bean were 87.4 and 85.5%, respectively. The precision of the method studied was no better than that of the current official final action method, 29.121–29.127, and its adoption is not recommended.
Resolution of Aflatoxins B1, B2, G1, and G2 by High-Pressure Liquid Chromatography
Authors: Pons Walter A 
Published: February 2020

Abstract
Aflatoxins were completely resolved as sharp peaks in the order B1-B2-G1-G2 by high-pressure liquid chromatography on a small particle (10 μm) porous silica gel column in 7–13 min (B1 through G2) by a water-saturated chloroform-cyclohexane-acetonitrile elution solvent (25+7.5+1.0), with detection by ultraviolet absorbance at 360 nm. The relationship between peak height and amount injected was linear over a 5–400 ng range for each aflatoxin. Both retention times and peak heights were highly reproducible, multiple injections of mixed standards giving coefficients of variation of 1.0–1.4% (retention time) and 1.6–2.8% (peak height) for the 4 aflatoxins. Detection was highly sensitive, with mean peak height, mm/ng, of 7.1 (B1), 6.4 (B2), 4.5 (G1), and 4.1 (G2), allowing detection of 1–2 ng of each aflatoxin.