bluuebunny/crossref_metadata_2025 huggingface dataset:
Collaborative Study of a Joint AOAC-OICC Method for the Determination of Ash in Cacao Products
Authors: Iverson John L
Published: February 2020

A joint AOAC-OICC method for determining ash in cacao products, combining the best features of AOAC method 13.003 and OICC method 4a-E/1952 and with an ashing temperature of 600°C, has been developed. The results from an international collaborative study with 12 collaborators were in good agreement. The preferred method is pre-ashing of the sample under infrared lamps, followed by overnight ashing, thus eliminating reweighing at intervals to arrive at constant weight. The method for determining ash in cacao products has been adopted as official first action.
Organic Acids in Vanilla by Gas-Liquid Chromatography: Interpretation of Analytical Data
Authors: Schoen Kurt L
Published: February 2020

A method for interpreting data obtained by using AOAC method 19.046–19.048 for the gasliquid chromatographic determination of vanilla acids is given. Total adjusted peak heights of unknown extracts and authentic extracts are compared. The total organic acid content of the unknown extracts is expressed as a percentage of the total organic acid content of the authentic extract. Thus variations in operator techniques and gas-liquid chromatographic conditions are eliminated and a more accurate quantitative judgment regarding the vanilla bean content of the unknown sample can be made. Data on authentic and unknown vanilla extracts are given.
Simplified Coulson Electrolytic Conductivity Detector for Chlorinated Hydrocarbons
Authors: John L E St , Bache Carl A
Published: February 2020

A simple plug of Gas-Chrom Q as a gas flow restrictor inserted in the combustion tube of the electrolytic conductivity detector eliminates the need for expensive valving when the detector is used in the chlorine mode without a platinum catalyst.
Wet Oxidation Method for the Determination of Submicrogram Quantities of Mercury in Cereal Grains
Authors: Malaiyandi M , Barrette J P
Published: February 2020

A simple and rapid wet-digestion procedure is described in which flour samples containing bound and unbound mercury are decomposed, using a sulfuric-nitric acid mixture in the presence of small amounts of vanadium pentoxide. Fortification studies with 3 organomercuric compounds on mixed cereal flour indicate average recoveries in excess of 96% in the 20–500 ppb range. This wet digestion method is compared with the Klein procedure to illustrate the advantages and significance of the vanadium pentoxide oxidation.
Collaborative Study of an On-Column Periodate Reaction Method for the Analysis of Phenylpropanolamine Hydrochloride in Elixirs
Authors: Clark Charles C
Published: February 2020

Twelve laboratories collaboratively studied a method for the quantitative UV determination of phenylpropanolamine HC1 in elixirs. The phenylpropanolamine is separated from water-soluble impurities and strong acids by elution from a weakly basic Celite column. Further cleanup is accomplished by retention of the phenylpropanolamine on a weakly acidic column while the weak acids, weak bases, and organic-soluble neutrals are eluted. Phenylpropanolamine is eluted from the column after neutralization with NH3 and is converted to benzaldehyde via an on-column periodate reaction. The samples collaboratively studied consisted of 2 commercial and 2 synthetic elixirs. Recoveries of the synthetic elixirs averaged 100.1 and 101.8% for mixtures containing 5.05 and 12.52 mg/5 ml phenylpropanolamine HC1, respectively. The means and standard deviations for the commercial preparations were 4.75 ±0.12 and 12.34±0.16 mg/5 ml. The method has been adopted as official first action.
Gas Chromatographic Determination of Triarimol in Formulations and Technical Material
Authors: Frank Richard , Decker Oliver D , Day Edgar W
Published: February 2020

The triarimol content in formulations and technical materials is determined by flame ionization gas-liquid chromatography after the sample is dissolved in or extracted with chloroform. Pesticides commonly occurring with triarimol do not interfere in this method. Replicate injections of emulsifiable concentrate and wettable powder samples showed good precision.
Gas-Solid Chromatographic Determination of Oxygen, Nitrogen, Carbon Dioxide, Ethylene, and Nitrous Oxide at Ambient Temperature
Authors: Finkelson Martin J
Published: February 2020

A gas-solid chromatographic method is described for the separation and determination of 5 medicinal gases at ambient temperature, using 2 gas chromatographic columns, Porapak Q and Molecular Sieve 13X, operated in series with a 6-port thermal conductivity detector and I recorder. An electronic digital integrator is used for calculating peak areas. Data on retention time, linearity, reproducibility of injection, and comparison with absorption methods are presented. Analytical results for oxygen, nitrogen, carbon dioxide, ethylene, and nitrous oxide are attainable within 1.0% without the use of an internal standard.
Determination of Oxalic Acid in Foods
Authors: Franco Vincent , Krinitz Benjamin
Published: February 2020

Two methods for the determination of oxalic acid were collaboratively studied. In both methods, the oxalic acid in spiked and unspiked spinach is precipitated as calcium oxalate from a buffered (pH 4.0–4.5) solution. The precipitate is separated from the solution by centrifuging 15 min at 1700 rpm. The oxalic acid is determined either by titrating the oxalate in the precipitate with potassium permanganate or measuring the calcium in the precipitate by atomic absorption and calculating it as oxalic acid. Mean recoveries of oxalic acid added at the 175 mg/100 g level were 99.5 and 100.5% for the titration and atomic absorption methods, respectively. Mean recoveries at the higher levels were 99.4% (315 mg oxalic acid added/100 g) and 97.8% (350 mg/100 g), respectively.
Gas-Liquid Chromatographic Determination of Phenothiazine in Medicated Feeds
Authors: Colvin Billy M , Prudom Albert E , Whitlock Larry L , Hanks Alan R
Published: February 2020

A simple and rapid method is described for the determination of phenothiazine in feeds. Phenothiazine is extracted with chloroform containing chlorobenzilate as an internal standard. The extract is injected into a gas chromatograph and peak height ratios are used for quantitation. The analysis of commercial samples shows that the method compares well with the more commonly employed colorimetric AOAC method, and good precision, with recoveries ranging from 96.0 to 99.9%, is obtained in the analysis of prepared samples.
Modified Soxhlet Thimble Holder for Multiple Fat Extractions
Authors: Prosky Leon , O’Dell Roger G
Published: February 2020

A modified Soxhlet extraction thimble holder has been designed to permit the extraction of 8 samples in an apparatus formerly used for 1 sample.
Infrared Identification and Potentiometric Determination of Glycine in Dietetic Beverages
Authors: Coppola Elia D , Hanna J Gordon
Published: February 2020

Infrared identification and nonaqueous potentiometric and visual titration of glycine in diet drinks is described for samples containing as little as 0.2% glycine. Sodium benzoate and saccharin do not interfere in the glycine determination. An average recovery of 99.3±1.00% was obtained for added glycine for a series of 7 determinations.
Collaborative Study of the Multicomponent Method for Polycyclic Aromatic Hydrocarbons in Foods
Authors: Fazio Thomas , White Richard H , Howard John W
Published: February 2020

A collaborative study was conducted on the multicomponent method for polycyclic aromatic hydrocarbons in foods. Samples of smoked ham fortified with benzo(a)pyrene, benzo(e)pyrene, benz(a)anthracene, and benzo(g,h,i)perylene were analyzed by 12 collaborators. Average per cent recovery at the 10 ppb (μg/kg) level for the 4 compounds ranged from 70 to 90%. The within-laboratory standard deviation indicates that the precision of the method is not significantly different for any one of the hydrocarbons. The method has been adopted as official first action.
Reverse Phase Thin Layer Chromatography of Some Aroclors, Halowaxes, and Pesticides
Authors: Stalling David L , Huckins James N
Published: February 2020

The components of Aroclors® 1232, 1248, 1254, and 1260; Halowaxes® 1099, 1013, and 1014; and several chlorinated pesticides are resolved by reverse phase thin layer chromatography (RPTLC), which permits component separation by partition between a nonpolar stationary phase and a polar mobile phase. Rf values of resulting spots were calculated for 2 of 4 new solvent systems (mobile phases). RPTLC patterns were reproducible and characteristic of each material examined. The spots were recovered from the plates and characterized by gas-liquid chromatography (GLC) and/or GLC-mass spectrometry. In some cases, single GLC peaks of Aroclor standards were resolved into more than one component by RPTLC, whereas some RPTLC spots of Halowaxes were resolved into as many as 4 GLC peaks. The analysis of environmental residues of chlorinated compounds was facilitated by this technique.
Comparison of Gravimetric and Volumetric Sodium Tetraphenylboron Methods for Determining K2O in Fertilizers
Authors: Melton James R , Hoover William L , Howard Peggy A
Published: February 2020

The official final action volumetric sodium tetraphenylboron method for determining potassium in fertilizers, 2.090–2.092, is compared with a gravimetric modification of the method. The modified method, which is less time consuming than the official method, is described. Seven Magruder check samples were analyzed by both methods and results compare favorably. Advantages and disadvantages of both methods are discussed.
Rapid, Sensitive Method for Determination of Mercury in a Variety of Biological Samples
Authors: Deitz Frank D , Sell Jerry L , Bristol Douglas
Published: February 2020

A simple, rapid method for the routine determination of mercury at levels as low as 2 ng (2 ppb) in a wide variety of biological samples is described. Vanadium pentoxide-catalyzed wet digestion at 140°C is used for complete oxidation of organic tissue. Mercury is determined by flameless atomic absorption spectrophotometry, utilizing a syringe technique to transfer mercury-containing vapor to the absorption cell. Replicate analyses of samples on different days showed good precision and accuracy. Coefficients of variation for determinations within a day’s run ranged from 2 to 17% at mercury concentrations of 30 to 40 ppb. Results obtained by this method agreed very closely with those obtained by neutron activation analyses of the same samples. On a routine basis, 2 analysts can analyze 30–40 samples/day.
Collaborative Study of a Gas-Liquid Chromatographic Determination of d-trans-Allethrin
Authors: Meinen Vernon J , Kassera Dean C
Published: February 2020

A gas-liquid chromatographic (GLC) method for the quantitative determination of d-trans-allethrin in technical materials and formulations was collaboratively studied. The samples are diluted with acetone and analyzed by GLC, using a flame ionization detector and a 5% OV-1 GLC column. A statistical evaluation of the matched pair technical samples shows an overall coefficient of variation of 0.34% and a coefficient of random error of 0.49%. An evaluation of the F-factor reveals no indication of systematic error contributions. A statistical evaluation of the results for 2 d-trans-allethrin formulations showed coefficients of variation of 4.98 and 1.98. An examination of the t-values revealed a small contribution to systematic error. The somewhat high results of sample C are believed to be a result of lower quality GLC resolution. The addition of a requirement for minimum GLC column performance to the method should increase the overall quality of the GLC resolution. The method has been adopted as official first action.
Free Acid in Esters of 2,4-Dichlorophenoxyacetic Acid and 2,4,5-Trichlorophenoxyacetic Acid and Their Formulations
Authors: Hammond Howard
Published: February 2020

The free acid content of 2,4-D and 2,4,5-T esters and formulations is determined by titration to pH 7.0, using a pH meter. Average recoveries and standard deviations for 9 collaborators, analyzing 4 samples containing different amounts of the esters, were 0.2067± 0.0201 and 0.3778±0.0245 for 2,4-D ester and 0.6208±0.0555 and 1.4622±0.1356 for 2,4,5-T ester. The method has been adopted as official first action.
Collaborative Study of the Determination of Ammonia as an Index of Decomposition in Crabmeat
Authors: Steinbrecher Kurt
Published: February 2020

A colorimetric method for determining the ammonia content in crabmeat in various stages of decomposition was studied collaboratively. The method involves the color reaction between ammonia, thymol, and alkaline bromine water. The mean values for organoleptic Class 1, Class 2, and Class 3 of decomposition were found to be 281, 568, and 1376 μg NH3/g crabmeat, respectively. By statistical analysis these means were found to be significantly different from each other, and were found to arise from different populations. Useful cut-off points can be selected to separate the classes. The method has been adopted as official first action.
Collaborative Study of an Enzymatic Digestion Method for the Isolation of Light Filth from Fresh Pork Sausage
Authors: Gecan John S , Alioto Philip
Published: February 2020

An alternative method has been developed for the isolation of light filth from fresh pork sausage. The method involves particle size reduction, enzymatic digestion, wet sieving, deaerating, and floating with n-heptane-mineral oil from cooled 40% isopropanol. Collaborative study of the method showed the extraction papers and the recovery of light filth elements to be comparable to or better than those obtained for 40.B07. The method has been adopted as official first action as an alternative to 40.B07.
Thin Layer Chromatographic Test for Mammalian Urine on Wheat
Authors: Thrasher Joel J
Published: February 2020

Follow-up experimental work of the 1971 preliminary method study revealed the need for a change in sample size, an improved extract cleanup technique, and the identification of a urine-specific metabolite. A modified method collaboratively tested in 1972 is capable of handling a larger sample in the Soxhlet extractor. The extract is cleaned of interfering substances by chromatography with an appropriate solvent prior to 2-dimensional TLC. The indicator metabolites, urea, allantoin, and indican, are detected by sequential sprays. The collaborative study resulted in 90% correct positive determinations with no false positives. The minimum detection level is approximately 2 μl urine/9 g wheat. The method has been adopted as official first action.
Collaborative Study of a Column Chromatographic Method for Chlorothiazide, Methyclothiazide, and Polythiazide
Authors: Fazzari F Raymond
Published: February 2020

Chlorothiazide is eluted from a K2HPO4 column with acetic acid-ether solvent and extracted from the organic phase into HCl for the Spectrophotometric determination. Methyclothiazide and polythiazide are eluted from a NaHCO3 column with CHCl3 and measured directly. The method was collaboratively studied by 10 analysts. The average per cent recovered and standard deviations for preparations of chlorothiazide and methyclothiazide were 100.2±0.67 and 99.8±1.64, respectively. The method for chlorothiazide and methyclothiazide has been adopted as official first action.
Separation and Determination of FD&C Red No. 4 and FD&C Red No. 40 in Maraschino Cherries by Column Chromatography
Authors: Draper Ronald E
Published: February 2020

FD&C Red No. 4 and FD&C Red No. 40 are extracted from a sample-Celite mixture in a chromatographic column by elution with a 5% solution of Amberlite LA-2 liquid anion exchange resin in n-butanol. The colors are extracted from the resin with dilute ammonia and then extracted into n-butanol. After evaporation to dryness, the colors are separated by Celite chromatography, using pH 1.5 HCl buffer as immobile phase. Red No. 4 is eluted with n-butanol-CCl4 (1+1) and Red No. 40 is eluted with a 5% solution of Amberlite LA-2 resin in hexane. The compounds are measured spectrophotometrically. Results on a commercial sample (5 trials) ranged from 74 to 76 ppm Red No. 4 and 72 to 81 ppm Red No. 40. Spike recoveries at various levels averaged 98% for FD&C Red No. 4 and 95% for FD&C Red No. 40.
An Isolation and Cleanup Procedure for Low Levels of Organochlorine Pesticide Residues in Fats and Oils
Authors: Porter Mildred L , Burke Jerry A
Published: February 2020

An isolation and cleanup is described for low levels of organochlorine residues (about 0.005 ppm) in fats and oils, prior to electron capture gas-liquid chromatography. The fat or oil is distributed on a column of unactivated Florisil and the residues are partitioned into an eluant of 10% water in acetonitrile. Florisil column chromatography with an elution solvent system comprised of mixtures of methylene choride, acetonitrile, and hexane is used for the final cleanup. Extracts prepared in this manner are sufficiently free of fatty extractives to permit injection of the equivalent of 50–60 mg fat sample for GLC. The procedure should be especially useful in determination of low levels of organochlorine pesticide residues in the fat of certain dietary composites.
Qualitative Identification of Furazolidone, Tylosin, and Zoalene in Feeds
Authors: Barefield Lewis A
Published: February 2020

Rapid microscopic methods are described for the identification of furazolidone, tylosin, and zoalene in mixed feeds at levels normally used for feeding. The drugs are identified by the colors produced in solution : furazolidone-intense blue in dimethylformamide and potassium hydroxide, zoalene—bright green in dimethylformamide and potassium hydroxide, and tylosin—pink-orchid in distilled water. Collaborative results showed excellent agreement, and the methods have been adopted as official first action.
Collaborative Study of a Qualitative Screening Test for the Detection of Cyanide in Wines and Spirits
Authors: Bates Brian L
Published: February 2020

Six laboratories collaboratively studied the method reported earlier for the qualitative detection of cyanide in wines and spirits at and below 0.1 ppm. Five samples of rectified spirit, labeled A, B, C, D, and E, and 5 samples of wine, labeled U, V, X, Y, and Z, were sent to each collaborator. Four of the 5 samples of both products were spiked with cyanide, in the form of K4FeCN6.3H2O, below 0.1 ppm. One sample in each set was free from cyanide and served as a blind blank. In the first study a total of 60 determinations were performed by the collaborators, plus the associated blank and standard determinations. Twenty validation determinations on 2 separate sets of both series of test samples were also performed in the Associate Referee’s laboratory prior to distribution of the samples. Because the results obtained from the overseas collaborators in the first study were not satisfactory and indicated that decomposition of the added potassium ferrocyanide had occurred during the unavoidably long period of transport and storage, all collaborators were asked to repeat the exercise on samples freshly spiked in their own laboratories and to report the results. The results obtained by the 3 collaborators in the second study were quite satisfactory and compared favorably with the results obtained by local collaborators in the first study. The method has been adopted as official first action.
Rabbit Eye Irritation Test: Collaborative Study
Authors: Marzulli Francis N , Ruggles Dennis I
Published: February 2020

The well known Draize rabbit eye irritation test was evaluated. Ten laboratories (3 government, 3 industrial, and 4 commercial) participated and 7 liquid materials were tested. Tests were conducted 2 at a time, using 1 of 6 different materials with the same control substance (70% isopropyl alcohol), for a total of 12 tests. Test materials were selected with stringency, by employing compounds which were difficult to evaluate as they were neither strongly irritant nor innocuous. By the Draize procedure, 5 of these materials were considered irritants, and 2 nonirritants. Results showed that if all 4 criteria for eye irritation (changes in cornea and iris and conjuctival redness and chemosis) were employed, collaborators were quite consistent in separating an irritant from a nonirritant substance. The method has been adopted as official first action.
Asbestos Fibers in Beverages, Drinking Water, and Tissues: Their Passage Through the Intestinal Wall and Movement Through the Body
Authors: Cunningham Hugh M , Pontefract Roderic D
Published: February 2020

Methods were developed using an electron microscope to isolate and count asbestos fibers in liquids and tissues. Fibers were detected in beer, sherry, port, vermouth, soft drinks, and city drinking water at levels generally ranging from 1 to 11 million per liter. River water was higher in asbestos fibers than water passed through a city filtration system, and melted snow was considerably higher than river water. Asbestos fibers were also detected in parenteral solutions. Distribution studies on asbestos fibers administered to rats were performed with the electron microscope and were supplemented with studies using both tritiated and neutron-activated asbestos. Crysotile fibers were injected into the stomachs of rats and 2–4 days later fibers were isolated from the blood, spleen, liver, kidney, omentum, muscle, lung, and brain. Highest levels of orally administered fibers were found in the omentum; intravenously injected fibers resulted in highest levels in the liver and the lung.
Simplified Spectrophotometric Analysis of Plants for Selenium
Authors: Olson Oscar E
Published: February 2020

A simplified Spectrophotometric method is described, which is based on the light absorption at 378 nm of the piazselenol formed by the reaction of 2,3-diaminonaphthalene with selenite. Reproducibility and recovery studies and comparison of the results with those obtained by fluorometric analysis, 3.074–3.078, suggest that the Spectrophotometric method is suitable for plant samples containing >2 ppm of the element. It can also be used in the measurement of selenium added to feed premixes or in the diagnosis of selenium poisoning in cattle by hair analysis.
Collaborative Study of a Microbiological Method for the Assay of Neomycin Sulfate in Feeds
Authors: Williams Billy Joe
Published: February 2020

The official method for the microbiological assay of neomycin sulfate in feeds was modified by adding pH 8.0 Tris buffer to and deleting CaC12 from the base and seed agars. The modified method was collaboratively studied by 13 laboratories. Each laboratory performed single assays of 4 feed types at 4 medication levels over 4 months. The average recovery for all collaborators was 115.6% of theory with a coefficient of variation of 20.4%. Neither order of assay, feed type, nor ratio of neomycin B to C in the premix significantly affected the assays. Inhibition zone diameters were significantly larger for standard solutions prepared in 1 + 24 dilutions of inactivated feed extracts than for identical concentrations of standard in 1+49 dilutions of identical feed extracts. This study has been discontinued and a search for a more reliable method has been initiated.
Determination of Chlorinated Pesticides in Whole Blood
Authors: Stretz Paula E , Stahr Henry M
Published: February 2020

Eight whole blood samples spiked with lindane, dieldrin, and p,p′-DDT at levels of 2.5, 12.6, 126, and 630 ppb each were sent to 11 collaborators for analysis. The method evaluated uses sulfuric acid to liberate the pesticides from the blood matrix. The pesticides are then extracted with 10% acetone in hexane. Pesticides were identified and quantitatively analyzed by gas-liquid chromatography, using an electron capture detector. Mean values at all levels are in good agreement with the spiking levels. However, statistical analysis of the data reveals a large systematic error. Further evaluation of the sulfuric acid method by comparison with other methods is recommended.
Examination of Automobile Paints by Laser Beam Emission Spectroscopy
Authors: Manura John J , Saferstein Richard
Published: February 2020

An analysis was performed on 112 paint chips of various colors from wrecked, late model automobiles. A laser beam microprobe was used in conjunction with an emission spectrograph in order to determine the applicability of the laser microprobe in forensic paint analysis and the specificity of the emission spectrograph in paint analysis. The emission spectrograph was employed to determine the relative abundances of elements in the surface layers of the paint chips. The laser microprobe attachment permitted the analysis of very small paint chips and the analysis of the surface layers of the multilayer paint chips. The results indicated that of the 112 paints analyzed (a) 11 pairs of paints which were physically identical could be distinguished by the emission spectrograph, (b) 4 pairs of paints which were physically identical were also identical by the emission spectrograph, and (c) 3 pairs of paints which were not physically identical were identical by the emission spectrograph. From the results it was concluded that, although the elemental composition cannot individualize a paint chip, it is a useful forensic technique when supplemented with a microscopic examination.
Analysis of Organic Acids in Fruit Products by Anion Exchange Isolation and Gas Chromatographic Determination
Authors: Baker David W
Published: February 2020

The method described involves passing an alcoholic extract of fruit product through a cation exchange resin column and then through an anion exchange resin column. Neutral fruit components are washed from the columns with alcohol and acetone solutions. Acidic components trapped on the anion column are eluted using 6N formic acid in acetone. An aliquot of the eluate is evaporated to dryness after the addition of benzene to remove the excess formic acid as an azeotrope. The residue is allowed to react with bis(trimethylsilyl)acetamide or bis(trimethylsilyl)trifluoroacetamide to form trimethylsilyl ether-ester derivatives which are detected by gas chromatography on a nonpolar (OV-1) column. Good recoveries were obtained for some common organic acids (succinic, fumarie, malic, tartaric, trans- aconitic, and citric acids) from fruit juice.
Quantitative Determination of Sorbitol in Raisins and Dietetic Foods by Gas-Liquid Partition Chromatography
Authors: Fernandez-Flores Enrique , Blomquist Victor H
Published: February 2020

A rapid method for the determination of sorbitol in raisins and dietetic foods is described. Sorbitol is converted to a trimethylsilyl derivative after precipitation of interfering organic acids as lead salts and determined by GLC, using α-d-glucoheptose as an internal standard. Nine samples of dietetic foods were analyzed. The results compared satisfactorily with the declared sorbitol content for each product. The recovery of 0.5% sorbitol added to raisins was 93%.
Criteria for Mycotoxin Standards
Authors: Rodricks Joseph V
Published: February 2020

It is recommended that all samples of mycotoxins to be used as analytical standards be in compliance with certain criteria of purity and that methods be made available for analysts to check the concentration and purity of their standards. General criteria for meeting these goals are described. A procedure for the determination of the concentration and purity of aflatoxin M1 standards, which was used in an IUPAC collaborative study to determine the stability of M1, is recommended for acceptance by the AOAC.
Chemical Confirmation of BHC Isomers : Comparison of Alkaline Reactions in Solution and by Gas Chromatographic Pre-Column
Authors: Cochrane William P , Maybury Ronald B
Published: February 2020

A rapid procedure that involves treatment with sodium methoxide (NaOMe) solution is described for the qualitative confirmation of lindane (and other BHC isomers) residues in cereal, animal feed, meat, and fat samples. Losses encountered in the evaporation and partition steps are discussed. Optimum GLC conditions, both programmed and isothermal, for the separation of the 1,3,5-, 1,2,4-, and 1,2,3-trichlorobenzene products are given. Comparison of the NaOMe solution reaction with an alkaline pre-column technique revealed that the latter saved time in the analysis of cereal, animal feed, and cheese extracts. The alkaline pre-column method did not eliminate interferences in some meat and fat samples; the NaOMe solution reaction does eliminate these interferences. A lower level of 0.01 ppm lindane in a 10 g sample can be confirmed by the procedures described.
Neutron Activation Analysis for the Detection of Firearm Discharge Residues Collected on Cotton Swabs
Authors: Michael Hoffman C
Published: February 2020

Cotton swabs moistened with 5% HNO3 are frequently used by police investigators to process a suspect’s hands for the presence of gunshot residue. A neutron activation analysis procedure is described for testing these swabs for barium and antimony, which are commonly found in firearm residues. The limitations of the method are also discussed.
Determination of Chlorinated Insecticides in Suspended Sediment and Bottom Material
Authors: Goerlitz Donald F , Law Leroy M
Published: February 2020

Chlorinated hydrocarbon insecticides in suspended sediment and bottom material are extracted with acetone-hexane solvent, with the extractants added separately. Co-extractives, including polychlorinated biphenyls and polychlorinated naphthalenes, are isolated by adsorption chromatography. Sulfur is removed by precipitation. Mean recoveries from 8 spiked samples ranged from 75 to 99% for 9 chlorinated hydrocarbon insecticides. An average recovery of 97.9% was obtained for bottom material samples contaminated with chlorinated hydrocarbons. Recoveries were compared with those obtained by exhaustive extraction of the contaminated samples.
Atomic Absorption Spectrometric Determination of Arsenic
Authors: Hoover William L , Melton James R , Howard Peggy A , Bassett James W
Published: February 2020

The official AOAC method for arsenic in feeds has been adapted to an atomic absorption spectrophotometric technique in which the arsenic trapped in the absorbing solution is aspirated into the flame. Values as low as 0.5 μg As/g can be measured in a 10 g sample. A modified digestion procedure is described. A second method is described for the determination of submicrogram quantities of arsenic whereby the arsine gas is generated into a plastic bag and introduced directly into the flame. Air-acetylene fuels are utilized, requiring no alterations in the nebulizer and mixing chamber. Sensitivity attained from a 10 g sample is 0.1 μg As/g. Results of various biological matrices, which were determined by the AOAC method and the 2 described methods, compare favorably.
Thin Layer Chromatographic Quantitative Analysis of Polythiazide Tablets
Authors: Flinn Paul E , Smith Thomas G
Published: February 2020

A thin layer chromatographic method, using methylene chloride-methanol (90+2) as a developing system, for the quantitative analysis of polythiazide is described in which the polythiazide is concentrated over a visible area of less than 2 sq mm adsorbent (SilicAR 7GF) on a glass plate or fiber glass sheet (SAF type) for ease of elution. Data from 5 determinations showed a coefficient of variation of 0.63% with a range of ±0.75% at the 100 μg spotting level.
Automatic Potentiometric Titration of Sodium Chloride in Certifiable Water-Soluble Colors
Authors: Graichen Charles , Bailey John E
Published: February 2020

A Fisher Titralyzer® is used for a rapid automatic potentiometric determination of sodium chloride in certifiable colors. The sulfonated colors are dissolved in water and the solution is titrated. The water-soluble fluorescein colors are first precipitated with acid, and an aliquot of the filtrate is titrated. The method is applicable to all certifiable water-soluble colors except D&C Red No. 19.
Rapid Procedure for Determination of Formaldehyde in Maple Sirup
Authors: Karasz Albert B , DeCocco Frank , Maxstadt John J , Curthoys Allan
Published: February 2020

A modification of the official AOAC method, 31.184—31.186, has been developed which requires no distillation. The acetylacetone reagent is added directly to a diluted sirup sample. The color formed is extracted with isobutanol and the absorption of the extract is measured at 415 nm against a blank extract processed without acetylacetone. Standard curves are prepared, as in the official method, with spiked sirups. The proposed method measures 42.3% of the formaldehyde present; the official method measures 27.1%. Results obtained using the modification compare well with those obtained by the official method and show equivalent precision. A determination can be completed in 1 hr and a large number of samples can be processed simultaneously.
Direct Chromatography of Some N-Methylcarbamate Pesticides
Authors: Lorah Esther J , Hemphill Delbert D
Published: February 2020

Carbaryl (1-naphthyl methylcarbamate), Mesurol® (4-methylthio-3,5-xylyl methylcarbamate), promecarb (m-cym-5-yl methylcarbamate) , Zectran® (4-dimethylamino-3,5-xylyl methylcarbamate), and 4-dimethylamino-3,5- xylenol were successfully chromatographed on Chromosorb W support, surface-modified with Carbowax 20M. The intact compounds were detected by means of the nitrogen or sulfur response of an alkali flame detector. Calibration curves were linear over the range 4 to 2000 ng. Average pesticide recoveries of 90—100% were obtained from fortified vegetable samples.
Determination of Tough Strings and Fibrous Material in Frozen Green Beans
Authors: Varseveld George W
Published: February 2020

Two methods were collaboratively studied: a method for the determination of tough strings in frozen green beans, adapted from the Food and Drug Administration method for canned green beans, and a method for the determination of fibrous material. Results from 5 collaborators for the tough strings method indicate substantial intralaboratory error. Coefficients of variation were between 20.0 and 25.6% for 3 samples containing 10 to 22% tough string units. Inherently high sample variation is a problem. It is recommended that the tough strings method be given further study. Six collaborators assayed fiber in 4 pairs of frozen green bean samples. Statistical results revealed standard deviation values ranging from 0.010 for a sample averaging 0.14% fiber to 0.025 for a sample averaging 0.33% fiber. The proposed method has been adopted as official first action.
Collaborative Study of Ion-Pairing Column Chromatographic Determination of Neostigmine Bromide
Authors: Kling Rita E
Published: February 2020

A revised version of the ion-pairing column chromatographic method for neostigmine bromide in tablets and ophthalmic solutions was subjected to a collaborative study. Eleven collaborators assayed a commercial tablet preparation, a simulated tablet formulation, 5 individual tablets, and a simulated ophthalmic formulation. The relative standard deviations were 2.2, 1.8, and 1.5% for the 2 tablet samples and the ophthalmic solution, respectively, and 2.4% for the individual analysis. The method has been adopted as official first action.
Determination of Soy Products in Meat-Soy Blends
Authors: Formo Marvin W , Honold Guy R , Maclean David B
Published: February 2020

The concentrations of various elements and fiber in ground beef and textured soy flour were measured, respectively, by atomic absorption spectrophotometry and a modified AOAC fiber method. The average concentration, standard deviation, and coefficient of variation for magnesium, manganese, and fiber, respectively, in textured soy flour are 2948 mg/kg, 186 mg/kg, 6.3% ; 33.4 mg/kg, 3.4 mg/kg, 10.1% ; 2.03%, 0.27%, 13.3%. The average concentration, standard deviation, and coefficient of variation for magnesium, manganese, and fiber, respectively, in regular ground beef are 151 mg/kg, 7.4 mg/kg, 4.9% ; 0.125 mg/kg, 0.025 mg/kg, 20%; 0.01%. From computer analysis of the data from an interlaboratory study of the analysis of textured soy flour–ground beef mixtures, the expected total errors (one standard deviation in absolute percentages) of the method applied to a product containing 20% textured soy flour hvdrated 1+2 were as follows for the respective indices used: magnesium 1.8%, manganese 2.7%, and fiber 8.8%. Analysis of ground beef and textured soy flour for ash, hemicellulose, stachyose, phosphorus, potassium, copper, and zinc revealed that these constituents were not suitable indices of textured soy flour content in textured soy flour-ground beef mixtures.
Evaluating the Potential for Occurrence of Aflatoxins in Black Sunflower Seeds
Authors: Llewellyn Gerald C , Eadie Thomas
Published: February 2020

A modified cotttonseed extraction and purification procedure was used to detect aflatoxins in samples of sunflower seeds. No aflatoxins (< 2 ppb) were detected in over 50 random samples taken from varied lots of commercial seeds on sale in central Virginia. No Aspergillus flavus-like or A. parasiticus-like organisms were seen in cultures of the natural flora of such seeds when grown on both whole and crushed seeds. No naturally occurring aflatoxins (< 2 ppb) were detected in the cultures. Standing cultures of crushed seeds, when inoculated with A. flavus ATCC 15548, resulted in 271 μg total aflatoxin/g medium within a 2 week period of growth at room temperature. The crushed seed cultures had the following ratios for B1, B2, G1, and G2: 12, 1, 17, and 3, respectively. Whole seed cultures tested about 25% lower than crushed cultures for total aflatoxin content but whole cultures did lack detectable levels of B2. The whole seed cultures had the following ratios for B1, B2, G1? and G2: 13, 0, 19, and 2. The increase in toxin levels in the crushed cultures for each type of toxin compared to the total increase was as follows: G1 increased 37%, B1 increased 29%, G2 increased 21%, and B2 accounted for 12% of the total increase. Black sunflower seeds, whole or crushed, will support the growth of A. flavus and the production of aflatoxins at levels that may approach that of rice medium but not that of coconut medium.
Thin Layer Chromatographic Determination of Aflatoxins in Wine
Authors: Takahashi David M
Published: February 2020

A thin layer chromatographic (TLC) method is described for the determination of aflatoxins B1, B2, G1, and G2 in wine. Aflatoxins are extracted from wine with methylene chloride and the concentrated sample extract is subsequently cleaned up on a silica gel-alumina column prior to TLC analysis. The recoveries of B1, B2, G1, and G2 from 13 samples of various wines at the spiked levels of 2 μg/L (B1 and G1) and 0.4 μg/L (B2 and G2) were approximately 90–100%, as measured visually. The proposed method is sensitive to at least 0.25 μg aflatoxin/ L wine.
Vitamin A in Mixed Feeds, Premixes, and Foods: Development of Method
Authors: Parrish Donald B
Published: February 2020

The present official final action method for determining vitamin A in feeds, 39.008–39.013, was simplified where possible and modified to provide alternative procedures so that it could be used to analyze different types of feed and food products. Among the changes were the following: making fewer extractions, solution transfers, and dilutions to volume; using smaller aliquots; and eliminating chromatography. There was less change in the method for samples of low vitamin A content and those containing carotenoid pigments. A biopotency test was added to provide a basis for converting analytical values of vitamin A stated in μg to USP units.
Polarographic Determination of Niacinamide in Multivitamin Preparations
Authors: Taira Albert Y
Published: February 2020

Niacinamide is extracted from multivitamin preparations with sodium bicarbonate solution. The extract is mixed with Celite and packed into a chromatographic column. The vitamin is eluted with 10% re-propanol in ether and the eluate is evaporated to dryness in the presence of hydrochloric acid. The residue is dissolved in potassium chloride solution and diluted to volume. The polarogram, from –1.40 to –1.90 v, is recorded on a polarograph equipped with a dropping mercury electrode and an H-cell with a saturated calomel reference cell. Additional assays with chemical and microbiological methods showed comparable results. The method is sensitive to 2 mg niacinamide.
Collaborative Study of Clopidol in Chicken Tissues and Eggs, Using Gas-Liquid Chromatography
Authors: Leroy Bjerke E , Herman James L
Published: February 2020

Ten collaborators participated in a study of an improved method for determining residues of the coccidiostat clopidol (3,5-dichloro-2,6- dimethyl-4-pyridinol) in chicken tissues and eggs. Tissues are extracted with methanol and the extract is cleaned up with columns of alumina and anion exchange resin. After methylation with diazomethane reagent, clopidol methyl ether is determined by gas chromatography with electron capture detection. The method is applicable to levels as low as 0.1 ppm in chicken tissues and 0.05 ppm in eggs. Results from 9 collaborators gave an average recovery of 84% from muscle, 90% from liver, and 84% from eggs. Results from an unknown sample of each substrate were excellent. The method has been adopted as official first action.
Fluorometric Determination of Diethylstilbestrol at Low Levels in Animal Feeds
Authors: Ponder Carl
Published: February 2020

A fluorometric method has been developed to determine diethylstilbestrol (DES) at the 5 ppb level in liquid and dry animal feeds. DES is extracted from the feeds, using a mixture of acetone-isoamyl alcohol (1+1) after an initial treatment with acetic acid-ethylene glycol (1+4). Solvent partitioning further isolates the DES which is irradiated in a buffered solution with ultraviolet light to form the neutral phenanthrenedione derivative. The dione is extracted from an alkaline solution and converted to the phenolic phenanthrenediol derivative in an acidified bisulfite solution. The diol derivative is further isolated by solvent partitioning and is determined fluorometrically in methanol. Recoveries on 7 samples (examined by 5 analysts) spiked with SO ppb DES ranged from 70 to 117%. Recoveries on 2 samples spiked at 5.5 and 5.9 ppb were 89 and 100%, respectively. The recoveries on 2 samples of commercial feed, prepared to contain 5.6 ppb DES by adding a calculated amount of blank feed, were 91 and 95%.
Evaluation of Hektoen Enteric Agar for the Detection of Salmonella in Foods and Feeds
Authors: Bisciello Neil B , Schrade John P
Published: February 2020

Over the past 2 years in our laboratory, Hektoen enteric (HE) agar was evaluated as a medium for the detection of salmonellae in foods and feeds. HE agar was used in conjunction with brilliant green, bismuth sulfite, and Salmonella-Shigella agars, according to AOAC methods. More than 2000 samples representing over 40 different products were tested and the cultural results on all media were compared. HE agar was more efficient than the other media for recovery of salmonellae in contaminated samples and showed a lower number of false positives. HE agar is a highly selective medium for Salmonella species and we recommend that it be evaluated for incorporation into the AOAC methods.
Automated Method for the Analysis of Thiamine in Milk, with Application to Other Selected Foods
Authors: Kirk James R
Published: February 2020

An automated method for the determination of thiamine in milk and food products is described. The procedure involves the oxidation of thiamine to thiochrome, extraction into isobutanol, and fluorescence measurement. The automated procedure gave a mean recovery value of 92.7% and a standard deviation of ±0.7%, compared to 83.3±2.5% for the manual procedure. The procedure is simple, rapid, and accurate, and markedly shortens the average time for analysis.
Isolation, Detection, and Quantitation of Zearalenone in Maize and Barley
Authors: Mirocha Chester J , Schauerhamer Beth , Pathre Sadanand V
Published: February 2020

A versatile method for the detection of zearalenone is described, employing options of either thin layer chromatography (TLC), gas-liquid chromatography (GLC), ultraviolet chromatography, GLC-mass spectrometry, or combinations of all of these. Zearalenone is extracted with either a Soxhlet apparatus or the more rapid and convenient batch extraction technique with equal efficiency. Cleanup of the extract involves either a base (NaOH) treatment and partition with water or an acetonitrile- petroleum ether partition. A chloroformethanol (97+3) solvent system is used for analysis by TLC with confirmation by fluorescent properties. The limit of detection on the TLC plate is 0.1 μg, while the sensitivity for the TLC method is about 50 ppb. Best quantitative results are obtained by analytical procedures involving GLC. The limit of sensitivity by GLC is less than 50 ppb. The derivatives dimethoxyzearalenone and methyl oxime-di- TMS-ether-zearalenone are prepared to confirm the presence of zearalenone. Zearalenone can also be analyzed both qualitatively and quantitatively by ultraviolet spectrophotometry. For quantitation, a standard curve is constructed of the absorption at 274 nm. The limit of detection is between 0.1 and 0.5 μg/ml. Analysis by combination GLC and mass spectroscopy is also described along with analysis by multiple ion detection. Per cent recovery is 83.5±7. The method described is suitable for analysis of the concentrations of zearalenone normally encountered in nature and thought to be significant.
Spectrophotometric Determination of Piperazine in Pharmaceutical Preparations
Authors: Baggi Tulsidas R , Mahajan Surinder N , Ramana Rao G
Published: February 2020

A solution of piperazine or its salts is heated with 2,6-dichloroquinonechlorimide, and the color produced is measured at 525 nm to obtain the concentration of piperazine. The color developed obeys Beer’s law in the concentration range of 6.4–51.2 μg piperazine/ml. The results of the proposed method agree with those of the official methods within ± 1.0% for piperazine and its salts and ± 2.0% for formulations. The method is rapid and precise and gives reproducible results. It is suitable for the analytical control of piperazine or its salts and their formulations.
Identification of Impurities in Illicit Methamphetamine Samples
Authors: Barron Robert P , Kruegel Alice V , Moore James M , Kram Theodore C
Published: February 2020

Three impurities have been identified in illicit methamphetamine samples. One of these, N-formylmethamphetamine (N-methyl-N-(α-methylphenethyl) formamide), is an intermediate in the synthesis of methamphetamine by the Leuckart reaction. The remaining 2, ,α,α’-trimethyldiphenethylamine and α-benzyl-N-methylphenethylamine, are by-products of methamphetamine synthesis. Ultraviolet, infrared, nuclear magnetic resonance, and gas chromatographic- mass spectral techniques were used to identify these compounds. The data obtained are discussed and synthetic pathways are postulated to explain the presence of each compound in samples of methamphetamine.
U.S. Department of Agriculture Nutrient Data Bank
Authors: Murphy Elizabeth W , Watt Bernice K , Rizek Robert L
Published: February 2020

As part of its long-standing program for providing representative data on the nutrient composition of foods, the U.S. Department of Agriculture is developing a Nutrient Data Bank which, compared with the past, will have a far greater input of data from industry, an increase in the amount of data available for computer use, and an increase in the speed of releasing data to the public. A data submission form has been developed for use by those wishing to contribute data to the data bank. A coding system for classifying and retrieving data is in preparation. When operational, the Data Bank should provide information of use in food labeling. To help in evaluating data to be included in the Data Bank, a comparison of analytical methods used in determining minerals was made. This review showed that results by emission spectroscopy frequently did not agree well with data from other methods. Proper calibration and care in making determinations are needed for all methods, and especially for emission spectroscopy. There is a need for more certified reference samples of foods, to be used in establishing the accuracy of analytical procedures.