bluuebunny/crossref_metadata_2025 huggingface dataset:
Modified Delves Cup Atomic Absorption Determination of Lead in Blood
Authors: Barthel William F , Smrek Ann L , Angel Gloria P , Liddle John A , Landrigan Philip J , Gehlbach Stephen H , Chisolm J Julian
Published: February 2020

A modification of the Delves atomic absorption micro method for blood lead determinations is presented. The principal differences between the present modification and the original Delves method are the improvement in hardware to overcome problems in reproducibility and a char method to essentially eliminate the smoke peak which normally causes serious interference. The method has been applied to several different types of blood samples with excellent results.
Analysis of Thiamine in Pinto Beans by Gas Chromatography of the Sulfite Cleavage Product 5-(2-Hydroxyethyl)-4-methylthiazole
Authors: Seifert Richard M , Miller Charlotte Fung
Published: February 2020

A gas chromatographic method has been developed for the analysis of thiamine in pinto beans. The method should be applicable to other products. Thiamine is extracted and then quantitatively split by sulfite treatment to give the ether-extractable 5-(2-hydroxyethyl)-4-methylthiazole. The thiazole was analyzed by GLC. Its purity and identity were confirmed by mass spectrometry and GLC retention time. Total thiamine (as the HCl) calculated from the analyzed thiazole averaged 164 ±16 μg/25 g pinto beans. Recovery of total thiamine in 25 g pinto bean samples containing added thiamine HCl (100–500 μg) ranged from 97 to 83%. GLC analysis of pinto bean samples was in good agreement with analysis by the thiochrome method at levels of 5.9–8.6 μg/g, but results were more variable at lower levels.
Collaborative Study of a Gas-Liquid Chromatographic Method for the Determination of Water-Soluble Menadione (Vitamin K3) in Feed Premixes
Authors: Winkler Victor W
Published: February 2020

A GLC method for the determination of menadione bisulfite addition products in feed premixes was tested by 8 laboratories. Menadione sodium bisulfite complex (trihydrate) is extracted with methanol containing 1 mg diethyl phthalate/ml as internal standard and injected directly onto a 2% OV-17 (silylated) GLC column. The principle of the method is on-column pyrolysis of menadione bisulfite and subsequent GLC analysis of the pyrolytic product, menadione. The method is simple, rapid, and free from interference. The average recovery values for 4 samples at 16.0, 14.4, 4.0, and 3.6 g/lb ranged from 95.8 to 100.4% with coefficients of variations between 5.5 and 6.5%. The method has been adopted as interim official first action.
Quantitative Fluoro densitometric Determination of Quinine in Soft Drinks
Authors: Beljaars Paul R , Koken Paul J
Published: February 2020

A quantitative fluorodensitometric method is described for the determination of quinine in soft drinks such as tonic water, lemonades, and fruit juices. This method is based on treatment of sample with an alkaline mixture of methanol-25% ammonia (485+15), followed by TLC analysis on silica gel G plates. The plates are developed with a mixture of chloroform-methanol-acetic acid (80+20+3) in saturated tanks. After development, the TLC plates are scanned with a reflectance flying-spot densitometer. The relationship between recorded peak area and concentration of bluish fluorescent standard spots is linear for 0.1–1.0 μg quinine. HCI.2H2O. Coefficients of variation of 2.0–2.5% are obtained for the fluorodensitometric determination of quinine in spiked tonic water as well as fruit juice. Results obtained in this study are compared with those found by methods prescribed by the AOAC, van Gils and Hidskes, and Hey. Coefficients of variation for the direct and indirect UV Spectrophotometric methods range from 0.75 to 1.40%. Recoveries of 96.9–100.7% are obtained for spiked beverages analyzed by either the densitometric or the Spectrophotometric methods. Despite its lower accuracy, the fluorodensitometric method is suitable as a screening procedure for routine analysis and is applicable to the determination of quinine in several types of soft drinks.
Determination of Residues of Benomyl, Its Hydrolysis Product, and Thiabendazole in Various Crops
Authors: Aharonson Nadav , Ben-Aziz Abraham
Published: February 2020

An analytical procedure is described for residue determination of benomyl, its hydrolysis product, 2-benzimidazole carbamic acid methyl ester (MBC), and thiabendazole (TBZ) in various plants. The method involves acetone extraction, partitioning between acetone-water and ethyl acetate, and cleanup on a magnesium oxide-Celite-alumina column. Benomyl is quantitatively converted on the chromatographic column to MBC, whereas TBZ is unchanged. The compounds are quantitatively measured by direct fluorometric measurement of either MBC or TBZ. The method is sensitive to 0.1 ppm benomyl and 0.02 ppm TBZ. The results from check samples have shown very good reproducibility and accuracy.
Determination of Malathion in Enzymic Digests by the Ferric-Hydroxamate Method
Authors: Bhagwat Vasanti M , Ramachandran Bhikshandar V
Published: February 2020

The ferric-hydroxamate method of Hestrin for the determination of esters, when applied to aqueous suspensions of malathion, yields low absorbance values; the molar absorbance indicates that only one ester group is being hydroxamated. However, when the compound is dissolved in methanol the absorbance is doubled, both the ester groups presumably taking part in the reaction. With this modification the method is sensitive enough for routine assays of malathion residues. The absorbance is proportional to the amount of malathion between 0.5 and 2.0 μmoles. Malathion can be quantitatively recovered from aqueous media by a single extraction with cyclohexane. Aliquots of the extract are evaporated to dryness and the residue is dissolved in methanol and assayed. The procedure described is suitable for the analysis of a large number of samples, such as in malathion esterase studies, and may be used for the determination of malathion in formulations.
Gas-Liquid Chromatographic Determination of Dursban Insecticide (Chlorpyrifos) in Formulations
Authors: Fuzesi Martha
Published: February 2020

A simple and rapid gas-liquid chromatographic method is described for the quantitative determination of chlorpyrifos in liquid and granular formulations. The sample is extracted with benzene and equal amounts of sample and reference solution in the same concentration range are injected into a gas chromatograph equipped with an electron capture detector and an SE-30/Diatoport S column. Peak heights are used for quantitative measurements. The method has been applied successfully to laboratory-prepared and commercial samples.
Steroids in Aged Whisky
Authors: Black Robert A , Andreasen Arthur A
Published: February 2020

Steroids were isolated from aged whisky and identified as β-sitosterol-D-glucoside, β-sitosterol, stigmasterol, and campesterol. Only β-sitosterol-D-glucoside has been reported in whisky. These steroids were characterized by gas-liquid chromatography, thin layer chromatography, and infrared spectrophotometry. They are extracted from the barrel during maturation and can contribute to clarity instability in finished whisky products.
Automated Determination of Fat in Milk: Preliminary and Collaborative Studies
Authors: King Raymond L
Published: February 2020

The principles and operation of an Auto-Analyzer system are described and the system was compared to the Babcock method. Initial calibration studies verified the manufacturer’s claim of linear response between 2 and 6% fat. Homogenization and heat treatment caused slightly higher and lower results by the AutoAnalyzer system and the Milko-tester, respectively, when raw milk was used for calibration. Use of formalin as a preservative resulted in a positive bias of less than 0.04% fat. Mercuric chloride and potassium dichromate caused no effect. Standard deviation of the difference from the Babcock method for the calibration studies was less than 0.05%. The standard deviations ranged from 0.031 to 0.077 for 345 raw milk samples from individual dairy farms. Collaborative studies encompassed 15 samples ranging from 3 to 6% fat, including 3 blind duplicates plus calibration standards. Samples were analyzed in triplicate by 6 laboratories, using 2 methods of AutoAnalyzer calibration. The standard deviation was less for the AutoAnalyzer than for the Babcock method (0.048 and 0.047% fat, respectively). Differences between 3 pairs of blind duplicates were 0.013, 0.021, and 0.012% fat by the Babcock and AutoAnalyzer analyses, respectively.
Aflatoxin-Solvent Interactions Induced by Ultraviolet Light
Authors: Wei Ru-Dong , Chu Fun Sun
Published: February 2020

The effect of UV light on the fluorescence intensity of aflatoxins in various solvents and on the photocatalyzed addition of alcohols and water to the vinyl ether double bond of aflatoxins B1 and G1 was investigated. Four groups of new aflatoxins, designated as Bm, Be, Gm, and Ge, were found to result from the UV light-catalyzed aflatoxin-solvent interaction. These compounds were less toxic to chicken embryos than the parent toxins.
Method for the Determination of Aflatoxin in Animal Tissue
Authors: Brown Nathan L , Nesheim Stanley , Stack Michael E , Ware George M
Published: February 2020

The method consists of methanol extraction, purification of the extract by transfer from aqueous methanol to chloroform, silica gel column chromatography, partition chromatography according to Pons on a celluloseaqueous methanol column, and quantitation by TLC fluorodensitometry. Average recoveries of B1, B2, G1, G2, and M1 from liver, kidney, heart, and round steak spiked at 0.05, 0.1, and 0.2 μg/kg were 43–123% as measured by TLC fluorodensitometry. The method was successfully applied to the analysis of naturally contaminated liver, kidney, and heart tissues.
Analysis and Survey of Ground Black, White, and Capsicum Peppers for Aflatoxins
Authors: Scott Peter M , Kennedy Barry P C
Published: February 2020

Reports of contamination of condiments prepared from Piper nigrum (black and white pepper) and Capsicum spp. by toxicogenic strains of Aspergillus flavus pointed to the need for methods of analysis for aflatoxins in these products. Use of 2-dimensional thin layer chromatography readily allowed the detection of 1.3–2.5 μg aflatoxin B1, B2, G1, or G2/kg in pepper extracts obtained by AOAC official first action methods for the analysis of aflatoxins in peanuts and peanut products. Approximate percentage recoveries of the aflatoxins added to the ground pepper at levels of 10–40 μg/kg ranged from 60 to 100%. A survey of 24 ground black and white pepper samples and over 70 capsicum pepper samples for aflatoxins revealed the presence of low concentrations (up to about 8 μg aflatoxin B1/kg) in 3 types of capsicum pepper: ground cayenne pepper (10 of 17 brands), Indian chilli powder (6 of 6 brands), and crushed, dried chillies (1 of 1).
Spectrophotofluorometric Estimation of Low Levels of Diethylstilbestrol in Feedstuffs
Authors: Jeffus Marshall T , Kenner Charles T
Published: February 2020

A method for the determination of low levels of diethylstilbestrol in feedstuffs is described. Interfering feed extractives are removed by using a tripotassium phosphate-Celite column prior to irradiation. The dione produced by irradiation is oxidized to a phenanthrenediol and extracted into CH2CI2 for measurement of fluorescent intensity. The amount of diethylstilbestrol found in several feed samples ranged from 0 to 10 ng (0.0–0.5 ppb) with an average of 4 ng (0.2 ppb). Recoveries of 100 ng standards (equivalent to 5 ppb) added to the same samples averaged 91 ng with a standard deviation of 14 ng. Recoveries of 1000 ng standards (equivalent to 50 ppb) added to the same samples averaged 820 ng with a standard deviation of 14 ng. For 100 ng standards analyzed beginning with the irradiation procedure, the standard deviation was 5.6%, and for 1000 ng standards, the standard deviation was 2.8%.
Simplex Optimized Acetylacetone Method for Formaldehyde
Authors: Czech Fred P
Published: February 2020

The AOAC colorimetric acetylacetone method for formaldehyde in sugar products is optimized by means of the simplex experimental design process. The resultant method is almost 4 times as sensitive as the original AOAC method. It is about 33% more sensitive than the simplex optimized J-acid procedure and 45% more sensitive than the simplex optimized chromotropic acid method and, thus, represents one of the most sensitive methods now available. The average relative standard deviation is about ±2.7%. The limit of detectability is estimated to be 30 ppb. The didactic exposition of the simplex optimization process reported earlier is applied to the AOAC acetyl-acetone method. Further insights into simplex operations are provided and certain advantages of simplex application are pointed out. It is shown that, by sacrificing the high sensitivity of the optimized method the parameters of the new method result in about a 10-fold increase in analytical speed. Further application of kinetic considerations and the advantages of high quality, productivity, and economy in chemical analytical methods by means of the simplex experimental design process are described.
Semiautomated Method for More Precise and Sensitive Determination of Nonpolar Anticholinesterase Insecticides with Technicon Modules
Authors: Voss Günther
Published: February 2020

The problem of adsorption of relatively nonpolar anticholinesterase insecticides to Technicon® proportioning pump tubing is now eliminated by manually injecting sample solutions into a special injection chamber just downstream from the pump, rather than pumping them through tubing. Experimental results demonstrate that the problems of cross-contamination, prolonged interwash periods, shifts of baselines, and reduced sensitivity are satisfactorily solved by this technical modification.
Sensitive Cellulose Column for the Rapid Detection of Aflatoxins in Agricultural Products
Authors: Jemmali Mongi
Published: February 2020

A simple and rapid screening method has been developed for the detection of less than 5 ppb aflatoxin B1 in corn. Cellulose tubing is layered with acidic alumina, anhydrous sodium sulfate, and silica gel. The sample is applied to the column, which is developed in chloroform-acetonitrile-2-propanol. A sharp blue fluorescent band is an indication of the presence of aflatoxin. Sulfuric acid treatment, which will yield a yellow color in the presence of aflatoxin, may be used as a further confirmatory test.
Gas-Solid Chromatographic Determination of Carbon Monoxide and Carbon Dioxide in Cigarette Smoke
Authors: Horton Arthur D , Guerin Michael R
Published: February 2020

Gas-solid chromatographic methods are presented for the determination of carbon monoxide, carbon dioxide, or both simultaneously in the gas phase of cigarette smoke. The methods are optimized to allow quantitative determinations on the entire gas phase delivery of the cigarettes rather than single puffs and to allow the use of small numbers of cigarettes. Shortcomings of several sampling techniques are defined, and evidence is presented supporting the utility of Saran bag sampling and containment. Carbon monoxide and carbon dioxide analyses may be performed with relative standard errors of 2—3% and relative confidence intervals (95%) of 6—9% for determinations involving 4—6 cigarettes.
Automated Proof Determination of Liquors by Gas-Solid Chromatography
Authors: Venturella Vincent S , Graves Donald , Lang Robert E
Published: February 2020

A gas-solid chromatographic method, specifically designed for ease of automation, has been developed for the determination of the ethanol and/or methanol content of a variety of liquors. Both manual and automated procedures and results are described. The method is precise and accurate, and the results are comparable with the distillation/specific gravity technique. Using the automated procedure, 13 samples can be analyzed in duplicate during a workday.
Liquid Chromatographic Determination of Bergapten Content in Treated or Natural Bergamot Oils
Authors: Porcaro Peter J , Shubiak Peter
Published: February 2020

The method presented is a simplified and sensitive liquid chromatographic approach to the assay of the furocoumarin, bergapten, present in oil of bergamot. The method is faster and more reliable than thin layer chromatographicultraviolet assays currently in use. Various oils, treated and untreated, are tested for detection down to 0.001% or 10 ppm levels. Repetitive analyses give a standard deviation of 0.139 or a relative value of 1.61 %.
Gel Permeation Chromatographic System: An Evaluation
Authors: Griffitt Kenneth R , Craun John C
Published: February 2020

A gel permeation chromatography (GPC) system, including an automated GPC instrument, was evaluated and was found to be a reliable and efficient tool for fat-pesticide separations. In most cases more than 98% of the fat or oil was eluted from the column before the pesticides fraction began to elute. Cleanup efficiency was better than that obtained with acetonitrile partitioning, even when a petroleum ether backwash was used. Recoveries of several pesticides and industrial chemicals from milk fat were determined, with GPC as the only cleanup technique employed before gas chromatographic determination. Recoveries generally were better than those obtained with acetonitrile partitioning followed by Florisil cleanup. The automated instrument can be in operation unattended during non-working hours and, after loading, will automatically clean up 23 individual fat samples.
Rapid Gas Chromatographic Method for Screening of Pesticide Residues in Milk
Authors: Gabica Joe , Watson Michael , Benson Woodrow W
Published: February 2020

A rapid version of the official AOAC milk extraction method, modified to exclude lengthy chromatographic cleanup, is described. Lipid-soluble material is extracted with a diethyl ether-hexane mixture. Pesticides are then partitioned into acetonitrile and are reextracted with hexane. The concentrated hexane extracts are analyzed by gas chromatography, providing relatively sensitive results with a minimum of interfering extraneous peaks. This method may be useful in screening large numbers of samples and indicating those that may require more thorough analysis.
Gas-Liquid Chromatographic Determination of Acephate and Ortho 9006 Residues in Crops
Authors: Leary James B
Published: February 2020

A gas chromatographic method is described for determining acephate (O,S-dimethyl acetylphosphoramidothioate) and a metabolite, Ortho 9006 (O,S-dimethyl phosphoramidothioate), in a variety of crops. After extraction of the sample with ethyl acetate, the solvent is evaporated, and an ether solution of the residue is passed through a silica gel column to remove interferences. Acephate and Ortho 9006 are eluted from the column with 10% methanol in ether and measured simultaneously by programmed temperature gas chromatography, using an alkali flame ionization detector.
Multiresidue Method for the Determination of Triazine Herbicides in Field-Grown Agricultural Crops, Water, and Soils
Authors: Ramsteiner Klaus , Hormann Wolf D , Eberle Dieter O
Published: February 2020

A gas chromatographic multiresidue method is described for the following triazine herbicides: ametryn, atraton, atrazine, desmetryn, metoprotryn, GS-13529, GS-14254, terbutryn, prometon, prometryn, propazine, and simazine. The method consists of a methanol extraction, cleanup on an alumina column, and determination on a Carbowax column with nitrogen-, sulfur-, and chloride-specific detectors. Extraction and recovery data are given.
Chromous Chloride Reduction. VIII. Reaction of Some Derivatives and Degradation Products of Heptachlor with Chromous Chloride-Ethylenediamine Complex and Nuclear Magnetic Resonance and Mass Spectra of the Products
Authors: Chau Alfred S Y , Demayo Adrian , Apsimon John W , Buccini John A , Fruchier Alain
Published: February 2020

The use of the chromous chloride-ethylenediamine (CrCl2-en) complex to speed dechlorination and minimize side-products has been explored for heptachlor metabolites and degradation products. Five pentachloro heptachlor derivatives are synthesized, and their nuclear magnetic resonance and mass spectra are presented and discussed. Nuclear magnetic resonance data support the anti assignment of H- in the major products from CrCl2-en reduction of cyclodiene pesticides. The use of this reagent for possible development of chemical confirmatory tests for heptachlor metabolites and degradation products is also briefly discussed.
Modified Extraction Procedure for Ipronidazole in Feeds Containing Bentonite
Authors: Osadca Modest , Araujo Mercedes , De Ritter Elmer
Published: February 2020

The extraction procedure in the AOAC method for ipronidazole in feeds, 38.A01— 38.A07, has been modified to eliminate the interference of bentonite with recovery of ipronidazole from mash feed and pellets. Quantitative extraction from mash feed or ground pellets is achieved by shaking the sample with benzene after a brief soaking with warm, aqueous pH 8 buffer. Gas-liquid chromatography is used to measure ipronidazole in the benzene extract as in the AOAC method. A preliminary collaborative test of the modified method by 3 laboratories on 8 samples of feed containing 0, 2, or 5% bentonite yielded average assays of 0.0061, 0.0058, and 0.0062% ipronidazole, with coefficients of variation averaging 2.4, 6.2, and 4.4%, respectively. Further collaborative study of the modified method is recommended.
Semiautornated Determination of Ormetoprim in Feeds
Authors: Osadca Modest , Araujo Mercedes , De Ritter Elmer
Published: February 2020

An automated spectrofluorometric method has been developed for determining ormetoprim in feeds at use levels of 0.0037-0.0075%. After manual extraction involving enzyme digestion, blending with alkali and chloroform, and cleanup of the extract by solvent transfers, the oxidation and fluorescence measurement steps are fully automated. The automated system includes oxidation with permanganate, removal of excess permanganate with nitrous acid and of excess nitrous acid with urea, acidification, extraction of the fluorescent derivative with hexane-tert-amyl alcohol, and fluorescence measurement in a spectrofluorometer with a recorder and printout. Recoveries of ormetoprim added to feeds are good, the fluorescence response is linear over a suitable working range, and blank values on unmedicated feeds are negligible. Twenty to thirty extracts per hr can be assayed by the automated method with increased precision over an allmanual operation.
Comparison of Babcock and Roese-Gottlieb Methods for Determining Butterfat in Milk
Authors: Moore John M , Russell Sargent , Pelsue Neil H
Published: February 2020

Raw milk of varied fat content was analyzed by the Roese-Gottlieb and Babcock methods. The Babcock test level averaged 0.03 units higher than the Roese-Gottlieb test level for milk containing 3.066—5.580% butterfat. The standard deviations of the Babcock and Roese-Gottlieb methods were 0.039 and 0.010, respectively.
Evaluation of Automated Dye Binding Determination of Protein in Milk
Authors: Park Douglas L , King Raymond L
Published: February 2020

The Technicon AutoAnalyzer dye binding system for protein determination in milk was compared with the Kjeldahl and Udy methods. Individual cow and mixed herd milk samples were analyzed, including such variables as the effect of aging, chemical preservation, laboratory manipulation of protein content, and experimental changes in instrumental parameters. The Udy and Kjeldahl methods showed better agreement than the Technicon procedure in all treatments. Aging resulted in slight decreases in apparent protein content by both dye binding methods. Variation due to treatment with formaldehyde and mercuric chloride was considerable for the Technicon system (+ 0.72 and +0.20% protein, respectively). Individual cow milks varied more than herd milks and Guernsey more than Holstein milk. Milk samples standardized for protein content showed a high correlation with the Kjeldahl results. Replication by the Technicon system was superior to both the Udy and Kjeldahl methods. Performance of the Technicon system improved with increased dialyzing time, decreased dye concentration, and decreased sampling rate. Instrument performance was also influenced by dialysis membrance replacement.
CIPAC Collaborative Study of the Heat-Stability of Diazinon Formulations, Using Both CIPAC and AOAC Analytical Methods
Authors: Eberle Dieter O , Suter Rolf , Nowak Klaus , Bosshardt Hans P
Published: February 2020

Diazinon (O,O-diethyl O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate) and 3 different Diazinon formulations were analyzed both by the official CIPAC titrimetric method and by the AOAC official first action gas chromatographic method. In addition, all samples were subjected to the CIPAC accelerated storage test by heating (2 weeks at 54°C) and analyzed by the 2 methods before and after storage. Eight collaborators from European countries and the United States took part in the study. Analytical results were reproducible within and between laboratories by both methods. As demonstrated by an analysis of variance, the 2 procedures yielded identical results. Therefore, both the CIPAC and the AOAC methods may be considered as equivalent with good accuracy and reproducibility. After storage at 54°C for 14 days only one Diazinon dust formulation revealed a significant decrease in Diazinon content as shown by a t-test.
Gas-Liquid Chromatographic Determination of Diethylstilbestrol Monomethyl Ether in Diethylstilbestrol
Authors: Gainer Frank E , Chiasson William J
Published: February 2020

A gas chromatographic method is described for the determination of the monomethyl ether of diethylstilbestrol (MME) in diethylstilbestrol (DES). A 1 g sample of DES is dissolved in an aqueous solution of 0.5N sodium hydroxide and extracted with a chloroform solution containing benefin, the internal standard. The chloroform solution is back-extracted with sodium hydroxide, and an aliquot is chromatographed after silylation. The MME peaks (cis and trans') are measured relative to the internal standard peak. The method was tested for accuracy within the 120—2000 ppm range, and a linear plot of detector response vs. concentration was obtained. The method is also suitable for the determination of diethylstilbestrol dimethyl ether (DME) if present with MME in a DES sample.
Alkaline Distillation of Ammoniacal and Nitrate Nitrogen with Raney Catalyst Powder
Authors: Johnson Frank J , Miller Danish L
Published: February 2020

Raney catalyst powder was substituted successfully for Devarda alloy in the direct distillation of ammoniacal and nitrate nitrogen, and the catalyst powder was slightly more efficient than the alloy. Nitrate-containing fertilizer materials and some synthetic mixed fertilizers were analyzed by direct distillation with Raney catalyst powder as well as by accepted methods. The proposed method is precise and accurate, and is applicable to fertilizers containing ammoniacal and nitrate nitrogen and no other forms of nitrogen.
Liquid Chromatographic System for Separating Opium Alkaloids
Authors: Beasley Thomas H , Smith David W , Ziegler Howard W , Charles Richard L
Published: February 2020

A high-pressure liquid chromatographic procedure has been developed for the separation of 6 major alkaloids in gum or powdered opium. The alkaloids are absorbed from an aqueous dimethylsulfoxide solution onto a strong cation exchange resin and eluted with methanolammonia; the solvent is removed by reduced pressure evaporation. The alkaloids from the residue are then dissolved in chloroform-methanol (3+1). The sample solution, plus brucine alkaloid as an internal standard, is placed on a Corasil Type II column (microbore) and eluted with hexane that is gradient programmed with a solution of chloroform-methanol-diethylamine (100+300+1). The absorbance of the eluate is continuously monitored in a flow-through ultraviolet photometer.
Collaborative Study of the α-Toxin Method for Estimating Population Levels of Clostridium perfringens in Food
Authors: Harmon Stanley M , Kautter Donald A
Published: February 2020

A microbiological method for estimating population levels of Clostridium perfringens in food, based on the presence of α-toxin, was studied collaboratively in 15 laboratories. The collaborators extracted α-toxin from identical samples of roast beef and quantitatively determined it in hemolysin indicator plates. The titer of a-toxin found was utilized to estimate the population level of C. perfringens in the roast beef by correlating the titer of α-toxin present in the beef with experimental data on the relationship of viable counts and α-toxin production supplied to the collaborators. Forty-five of 52 samples examined were found to contain α-toxin at a dilution of 1+63 to 1+127 as measured in hemolysin indicator plates. The remainder had α-toxin titers one 2-fold dilution higher or lower. The estimated population levels obtained by the various laboratories ranged from 7.3 α 107 to 17.8 α 107/g. The standard deviation among replicate determinations within collaborators was 3.5 × 107/g. These results indicate that the precision of the α-toxin method makes it useful for estimating the maximum population of C. perfringens in a suspect outbreak food.
Automated Analyses of Sugar, Starch, and Amylose in Potatoes by Measuring Sugar-Dinitrosalicylate and Amylose-Iodine Color Reactions
Authors: Mccready Rolland M , Ducay Eufemio D , Gauger Mona A
Published: February 2020

Sugar-containing potato extracts were analyzed for sugars before and after invertase hydrolysis using Sumner and Sisler’s dinitrosalicylate method, modified and automated. Amylose and total starch were determined on sugar-free potato flour by automated methods, amylose was analyzed by the iodine color reaction, and starch as glucose was determined after hydrolysis with trifluoroacetic acid and reaction with dinitrosalicylate. Results were sufficiently reliable and satisfactory for surveying white potato samples for carbohydrates.
Ultraviolet Spectroscopic Determination of Dimetridazole in Feeds
Authors: Stone Loyal R , Hobson Dale L
Published: February 2020

A simple and rapid procedure for the determination of dimetridazole (l,2-dimethyl-5-nitroimidazole) in feeds is described, using only liquid-liquid extractions before ultraviolet (UV) measurement. The drug is more effectively separated from interfering substances by this method than by the 2 alumina chromatographic steps required in the official first action AOAC method. Dimetridazole is extracted from feed with chloroform and trisodium phosphate solution and transferred from chloroform into hydrochloric acid; sodium hydroxide is added to the solution and the drug is transferred into benzene for UV measurement. Ipronidazole and zoalene interfere. The presence of bentonite decreases recovery. The interference from natural feed ingredients is negligible. An average coefficient of variation of 1.9% and an average recovery of 98% were found on repetitive assays of 3 feeds of known dimetridazole content.
Organic Solvent Extraction of Lead and Cadmium from Aqueous Solutions for Atomic Absorption Spectrophotometric Measurement
Authors: Childs Ernest A , Gaffke John N
Published: February 2020

The efficiency of solvent extraction of lead and cadmium for atomic absorption spectrophotometry was investigated. Quantitative extraction from an aqueous solution into methyl isobutyl ketone was possible, using sodium diethyl dithiocarbamate in the pH range of 5.5—8.5 for Cd and 5.5—7.5 for Pb. A 4-fold concentration from aqueous to organic solvent allowed accurate measurement (error <± 10%) of concentrations <0.02 μg Pb/ml and <0.05 μg Cd/ ml. Detection limits of 0.01 μg Pb/ml and 0.0005 fig Cd/ml were established.
Collaborative Study of a Fluorometric Method for Determining Selenium in Foods
Authors: Ihnat Milan
Published: February 2020

A fluorometric method for the determination of selenium in foods reported previously was studied collaboratively. Nineteen laboratories reported analytical results on 10 samples representative of vegetables, cereal, dairy products, meat, and fish, and containing naturally occurring selenium. For the 5 pairs of samples, the coefficients of variation based on precision standard deviation were 2 5 . 9% at 16 ng selenium, 15.8% at 98 ng, 8.5% at 233 ng, 6.1% at 379 ng, and 4.1 % at 427 ng. The corresponding coefficients of variation computed from overall standard deviations were 65.3, 17.5, 8.9, 8.1, and 5.6%. Systematic error was significant for 2 pairs (F-test, p = 0.01), but not for the remaining 3 (p = 0.05). The ratio of the systematic error standard deviation to the precision standard deviation varied from 0.21 to 1.64. Analyses of 2 NBS standard reference materials, orchard leaves (75 ng selenium) and bovine liver (208 ng selenium), yielded results higher by 16 and 10%, respectively. The precision and accuracy of the collaborative procedure were deemed acceptable and the method has been adopted as official first action.
Adsorption Chromatographic Separation of Chlorinated Hydrocarbons from Lipids
Authors: Claeys Robert R , Inman Roderick D
Published: February 2020

Florisil, alumina, and silicic acid were compared for the column chromatographic separation of lipids from chlorinated hydrocarbons. Alumina had the largest capacity per unit volume to retain lipids and oils (0.7 g beef lipid/ 25 g alumina) while eluting dieldrin. Florisil had a larger capacity than silicic acid. Deactivation and elution with a nonpolar solvent gave superior separation over previously used polar solvent elution from activated adsorbents. The effects of temperature, water, and lipid load on the elution of dieldrin were studied. A yellow dye, p-methoxyazobenzene, was found to have a slightly larger elution volume than dieldrin, and is useful as a visible reference material for the elution of chlorinated hydrocarbons.
Identification of the Photoalteration Products Formed from Parathion by Ultraviolet Light
Authors: Joiner Ronald L , Baetcke Karl P
Published: February 2020

A comparison of the effects of various time periods of ultraviolet light on the formation of rearrangement products of parathion is presented. Twelve products were separated and identified by thin layer chromatography in 4 systems, and were confirmed by infrared spectroscopy, when possible. The effect of 2 solvents, methanol and acetone, on the formation and percentage composition of photoalteration products of parathion from high-intensity ultraviolet light is also discussed. Retention times are given for each component from gas chromatography by electron capture and flame photometric detection.
Applications of Nuclear Magnetic Resonance Spectroscopy to Certifiable Food Colors
Authors: Marmion Daniel M
Published: February 2020

Nuclear magnetic resonance spectroscopy (NMR) has been evaluated as a tool for the study of certifiable food colors and found useful as a means of identifying individual colorants, differentiating between single colors and mixtures, identifying and semiquantitating the colorants in secondary mixtures, establishing the presence of excipients such as sucrose, and detecting the adulteration of a color additive with forbidden colorants. NMR also shows promise as a method to examine the purity of food colors and to study process conditions.
Extraction and Analysis of Carotenoids in Fresh Plant Materials
Authors: Quackenbush Forrest W
Published: February 2020

Efforts were made to develop an improved method of analysis for the carotenoids in fresh plant material. The present official final action method (39.014—39.017) does not include analysis for xanthophylls. Use of ethanol as extractant compared favorably with the use of acetonehexane mixtures specified in the present method (39.015). Direct extraction of the residue after evaporation of an aliquot of the ethanol extract avoided xanthophyll losses that may be encountered in phasic partition. This extract was then chromatographed on silica gel G to separate carotenes and monohydroxy and dihydroxy pigments from non-pigmenting epoxy-xanthophylls. Magnesia chromatography of a portion of the ethanol extract followed by methanolic HC1 treatment of the xanthophyll fraction gave inconsistent results, apparently because of variable degrees of xanthophyll destruction by the HC1.
Collaborative Study of the Determination of Poly chlorinated Biphenyls in Paperboard
Authors: Finsterwalder Charles E
Published: February 2020

Eleven laboratories collaboratively studied a method for the determination of polychlorinated biphenyls (PCBs) (Aroclors 1242 and 1254) in paperboard, which involves alcoholic potassium hydroxide extraction, Florisil column cleanup, and electron capture gas-liquid chromatography. Blank paperboard spiked with 2 levels of each Aroclor and paperboard which had Aroclor 1242 incorporated during manufacture were analyzed. Average recovery of Aroclor 1242 at the 12.5 ppm level was 80.8%; at the 8.2 ppm level, 87.8%. Average recovery of Aroclor 1254 at the 12.3 ppm level was 87.0% ; at the 8.9 ppm level, 85.4%. The mean recovery of Aroclor 1242 from the specially prepared paperboard was 5.6 ppm, with a standard deviation of 15.8%. The method has been adopted as official first action.
Effects of Feeding Penicillin to Chickens
Authors: Katz Stanley E , Fassbender Carol A , Dinnerstein Paula S , Dowling John J
Published: February 2020

The feeding of penicillin to broilers and laying hens did not result in the deposition of any penicillin activity in the blood, muscle, liver, kidneys, or eggs. About 9 8% of the penicillin activity was destroyed in the upper portion of the intestinal tract with very little activity reaching the small intestine. When penicilloic acid, one of the degradation products, was fed to broilers it stimulated the development of lactosefermenting organisms in the intestinal tract, which showed antibiotic resistance as reflected by the streptomycin and tetracycline resistance markers.
Collaborative Study of a Modified Resazurin Test for Estimating Bacterial Count in Raw Maple Sap
Authors: Kissinger John C
Published: February 2020

A modified resazurin test technique for rapid estimation of bacterial counts in maple sap was studied in 13 collaborating laboratories. Statistical analysis of the collaborators' results indicates that this method can rapidly identify heavily contaminated sap which would yield low grade sirup or would be unsuitable for sirup manufacture. The method has been adopted as official first action
Semiautomated Batch System for Fertilizer Screening Analyses
Authors: Whittier Philip C , Forster Ann , McKinney James
Published: February 2020

A system has been developed for screening large numbers of fertilizer samples for nitrogen, phosphorus, potassium, and magnesium. The basis of the system is an assemblage of instruments found in virtually all fertilizer laboratories, supplemented by some specialized automatic aliquoting equipment. The methods that were in current use in our laboratory were streamlined and used in the system. The system has enough flexibility that other methods and instruments can be readily adapted to it. By using this system, we have reduced handling and costs, increased efficiency and production, and eliminated much analytical error.
Simple, Rapid Digestion Technique for the Determination of Mercury in Sea Food by Flameless Atomic Absorption Spectroscopy
Authors: Krinitz Benjamin , Holak Walter
Published: February 2020

A rapid digestion technique, using a Teflon vessel, for mercury determination by flameless atomic absorption spectroscopy was collaboratively studied. Average recoveries of added mercury to samples of freeze-dried shrimp and blended frozen tuna (8 collaborators) were 92, 87, 100, and 9 8% for levels of 0.25, 0.30, 0.45, and 0.50 μg, respectively, with standard deviations of 0.030, 0.046, 0.048, and 0.067. The digestion technique has been adopted as official first action.
Survey of Corn for Fusarium Toxins
Authors: Eppley Robert M , Stoloff Leonard , Trucksess Mary W , Chung Choong W
Published: February 2020

Samples of the 1972 corn crop were collected in areas where the potential for Fusarium contamination of the corn was considered to be high or where known Fusarium damage had been reported. The 223 samples were collected in the spring following the crop year from terminal elevators or from stocks on hand at food processing establishments and were analyzed for zearalenone, anatoxins, and T-2 toxin by a modified multimycotoxin detection method. A rabbit skin bioassay was used to screen for possible T-2 toxin at levels below the chemical detection limits. Zearalenone was found in 17% of the samples (0.1-5.0 mg/kg); anatoxin was found in 5 samples (trace-10 μg/kg). A skin irritant was found in extracts from 93 of 173 samples by the rabbit skin bioassay. This effect may be due to the T-2 toxin or some other mycotoxin.
Spectrofluorometric Determination of Lasalocid Sodium in Finished Feeds and Premixes
Authors: Osadca Modest , Araujo Mercedes
Published: February 2020

A simple, rapid, and sensitive chemical method is described for determining lasalocid sodium in finished poultry feeds and premixes. The drug is extracted with ethyl acetate directly from premixes and after a brief treatment with pH 4.7 buffer from finished feeds. Lasalocid sodium concentration is measured spectrofluorometrically and a correction for nonspecific fluorescence is determined after formation of a lasalocid- boric acid complex. Replicate assays of typical poultry mashes and pellets containing about 0.0075% lasalocid sodium yielded coefficients of variation of 2.8 to 5.0%. Average recovery of lasalocid sodium added in the laboratory at 0.0037, 0.0075, and 0.0112% was 90% with a pooled standard deviation of ±1.86%.
Determination of the Herbicide Isopropalin in Technical Grade Material and in Formulations
Authors: Dean Decker Oliver , Frank Richard
Published: February 2020

Two methods are described for the determination of isopropalin (2,6-dinitro-N,N-dipropylcumidine) in technical grade material (a concentrate in xylene) and emulsifiable concentrate formulations. Samples measured spectrophotometrically are purified by Florisil column chromatography. Samples measured gas chromatographically are dissolved in chloroform, mixed with the internal standard, and then injected into a gas chromatograph equipped with a flame ionization detector.
Collaborative Study of a Spectrophotometry Method for the Determination of Sorbic Acid in Fresh Dairy Products
Authors: Wilamowski George
Published: February 2020

A collaborative study has been completed on the determination of sorbic acid in 2 dairy products by a spectrophotometric method. Mozzarella cheese and cold pack cheese food were analyzed for sorbic acid. The sorbic acid was extracted from the dairy products with metaphosphoric acid and partitioned into a petroleum ether-anhydrous ether mixture. The concentration of sorbic acid was determined from its absorbance at 250 nm and its presence was confirmed by the disappearance of this absorbance maximum after shaking the ether solution with aqueous permanganate. The results obtained in the 10 collaborators’ laboratories were statistically evaluated. The average per cent recovery of sorbic acid in mozzarella cheese was 93.6—95.6 and in cold pack cheese food 90.7—101.9. A comparison was also made between the extraction procedure and the AOAC colorimetric method for sorbic acid in cold pack cheese food. The AOAC method had lower variability and higher per cent recovery for this product. The spectrophotometric method has been adopted as official first action as a screening procedure for sorbic acid in fresh dairy products.
Comparison of Culture Methods for Detection of Salmonella in Dried Active Yeast
Authors: Wilson Clyde R , Poelma Paul L , Andrews Wallace H
Published: February 2020

An improved procedure has been developed for the isolation of Salmonella from dried active yeast. Examination is presently made with a procedure employing pre-enrichment in 1% tryptone broth using a sample-broth ratio of 1:5, with subsequent transfers to selenite cystine (SC) broth and tetrathionate (TT) broth before streaking onto selective agars. The new method employs trypticase soy broth as the pre-enrichment medium using a samplebroth ratio of 1: 10, and subsequent transfers to lauryl sulfate tryptose (LST) broth and TT broth before streaking onto selective agars. The most significant points of change are samplebroth ratio and substitution of LST broth for SC broth. After a 24 hr pre-enrichment period, most probable numbers of the 5 Salmonella serotypes tested with the present procedure ranged from 13 × 103 to 7 × 105/ml compared with 13 × 106 to 49 × 107/ml using the new procedure. An incompatibility between active yeast and SC broth resulted in marked inhibition of 4 of the 5 Salmonella serotypes tested. LST broth was found to be highly productive for Salmonella growth and can be used in place of SC broth because of the absence of a large bacterial flora in dried active yeast. TT broth is retained as one of the selective broths in the event gross contamination is encountered and Salmonella becomes overgrown by non-salmonellae in the LST broth.
Collaborative Study of a Column Chromatographic Method for the Determination of Polythiazide in the Presence of Vanillin
Authors: Raymond Fazzari F , Levine Joseph
Published: February 2020

Polythiazide is eluted from a sulfanilic acid column with isooctane-ether solvent. The eluting solvent is then removed and the polythiazide is determined spectrophotometrically in methanol at about 268 nm. Vanillin is retained on the column as a Schiff’s base formed with the sulfanilic acid. The method was collaboratively studied by 9 analysts. The average per cent recovered and standard deviation for polythiazidevanillin preparations was 100.7±2.0. The method has been adopted as official first action.
Detection of Cashew Nut Shells in Coffee, Tea, and Chicory
Authors: Sengupta Pratima , Sen Asit R , Ghoshdastidar Nomita , Roy Bidhan R
Published: February 2020

Thin layer chromatography has been investigated for the identification of cashew nut shell, one of the common adulterants in ground coffee, tea, and chicory. The ether extract of the sample is applied to silica gel C plates and developed with benzene-dioxane-acetic acid (90+25+4) . Cashew nut shell shows 3 distinctive spots (Rf 0.7, 0.54, and 0.34) with diazotized benzidine which are totally absent in tea, coffee, and chicory. The spots have been identified as anacardic acid, cardol, and anacardol, respectively.
Differentiation of Caraway, Coriander, and Cumin by Study of Their Volatile Oils, Using Thin Layer Chromatography
Authors: Sen Asit R , Sengupta Pratima , Mondal Alpana , Roy Bidhan R
Published: February 2020

A rapid thin layer chromatographic test has been developed to differentiate caraway, coriander, and cumin. Samples are steam-distilled and 1% solutions of the volatile oils are chromatographed on silica gel G plates, using benzene- chloroform ( l+l ) as the solvent system. After exposure to iodine vapor, characteristic spots develop which can be used to distinguish and differentiate caraway, coriander, and cumin.
Determination of Methyl Salicylate in Root Beer
Authors: Markus John R
Published: February 2020

Root beer samples were analyzed for methyl salicylate by 17 laboratories, using the official final action AOAC method, 12.046-12.051. In this method, after the sample is distilled, methyl salicylate is extracted from the distillate with chloroform, and the compound is determined by gas-liquid chromatography. Recoveries of added methyl salicylate, 0.395 mg/ml, ranged from 0.349 to 0.428 mg/ml, with an average of 0.392 mg/ml. The average standard deviation and coefficient of variation were ±0.022 and 5.69%, respectively. On the basis of this study, procedural changes were recommended for method 12.046-12.051. They have been incorporated into the 12th Edition of Official Methods of Analysis.