bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Loss on Drying in Roasted Ground Coffee
Authors: McCarron Eleanor A
Published: February 2020

Moisture loss on drying was determined on five "regular grind" coffees by the air oven method at 105°C and vacuum oven method at 98—100° C before and after grinding. Results for unground and ground samples by the vacuum oven method were in good agreement; results between the two oven methods for unground or ground samples were generally less satisfactory. Collaborative study was conducted by the vacuum oven method only on four unground (as is) samples. Results were in reasonable agreement, and the method is recommended for adoption as official, first action.
Investigation of the Determination of Volatile Isothiocyanates in Mustard Seed and Flour
Authors: Rosebrook D D , Barney J E
Published: February 2020

A study of the variables in the AOAC and ASTA methods for determining volatile isothiocyanates in mustard flour and seed has led to development of a new method that is useful for both mustard flour and seed. The proposed method dispenses with the long reaction times and the digestion of the silver sulfide precipitate now required by the AOAC method. When mustard seed is analyzed, the ground seed is boiled in water for 3 min to solubilize the sinigrin, and yellow mustard flour is added as a source of enzyme. When mustard flour is analyzed, the boiling procedure is omitted Results are more reliable by the proposed method than by the AOAC or ASTA method and analysis can be completed in a single day.
An Improved Method for Determining Steam-Volatile Oil in Cassia
Authors: Rosebrook D D , Bolze C C , Barney J E
Published: February 2020

The variables that affect the determination of steam-volatile oil in cassia by the official ASTA method were examined in a preliminary study. On the basis of the results of this study an improved method was devised and was tested in a statistical program involving four types of cassias, two types of traps, two distillation rates, two sample weights, and two distillation times. Improvements in the method allow complete analysis in 3 to 5 hours, with an increase in the yield of steam-volatile oil and improved reliability.
Comparison of Flame and Burner Combinations in Atomic Absorption Spectroscopy
Authors: Perrin C H , Ferguson P A
Published: February 2020

Atomic absorption analyses of calcium, copper, iron, magnesium, manganese, and zinc on eight animal feed samples were conducted in which three different burners and six gas combinations were used under a variety of conditions. The statistical analysis demonstrated in most cases the superior accuracy of an oxygen-acetylene flame in a total consumption burner on solutions prepared by dry-ashing the samples.
Collaborative Study of Three Gas Chromatographic Dual Detection Systems for Analysis of Multiple Chlorinated and Organophosphorus Pesticides
Authors: Wessel John R
Published: February 2020

Six laboratories collaboratively studied three different gas chromatographic dual detection systems. The potassium chloride thermionic and electron capture detectors were arranged: (1) in parallel; (2) in series with a stream splitter between the detectors; and (3) in series. Systems 1 and 2 use the same type of thermionic detector, whereas a modification of this detector is used for System 3. Collaborative results show these systems to be equivalent for the quantitative measurement of multiple organophosphorus pesticides at 0.5 and 2.0 ppm. The pesticides studied were ronnel, ethion, Diazinon, malathion, methyl parathion, parathion, and carbophenothion. Operational and performance characteristics of dual detection and of thermionic gas chromatography are also discussed. It is recommended that all three systems studied be listed as official, first action for analysis of multiple pesticide residues
Improved GLC Method for s-Triazine Residue Determination
Authors: Tindle R C , Gehrke C W , Aue W A
Published: February 2020

An improved version of the alkali-flame detector with a movable electrode and rubidium sulfate as the coating material has been used for the analysis of atrazine, simazine, propazine, and prometryne. GLC conditions selected for optimum operation were as follows: column: 1.9 m X 3 mm i.d. Pyrex, packed with 10% w/w Reoplex 400 on 80—100 mesh Gas Chrom Z and operated at 200°C; flow rates: nitrogen 55 ml/min, hydrogen 30 ml/min, air 170 ml/min. When this technique was applied to the analysis of atrazine and simazine in corn, soil, and water samples, no purification of sample extracts was needed and recovery was quantitative. Minimum detectable limits were better than 0.5 ng triazine.
Collaborative Study of the Dye Binding Method Applied to Chocolate Milk Drinks, Cultured Buttermilk, and Half-and-Half
Authors: Sherbon J W
Published: February 2020

Collaborative studies of the dye binding method for chocolate-flavored milk drinks, cultured buttermilk, and half-and-half were conducted this year; ten samples of each product were tested in quadruplicate in seven laboratories. The precision of the method with these products was essentially the same as that for fluid milk. The withinlaboratory variations were very small and resulted in statistically significant interlaboratory variations; the actual differences were not of practical significance. It is recommended that these three products be accepted for testing for protein content by the dye binding method. Preliminary results on use of the dye binding method for analyzing nonfat dry milk show good precision; however, proper sampling and duplication procedures need to be established, and studies will continue. Studies will also continue on the required accuracies of reagent preparation, pH of buffer, and sample weighings to establish suitable tolerances.
Chemical Determination of Niacinamide in Multivitamin Preparations
Authors: Pelletier Omer
Published: February 2020

The AOAC method and the Pelletier and Campbell method for the assay of niacinamide in multivitamin preparations were compared in two collaborative studies. In the first study, three multivitamin sirup preparations were analyzed by six laboratories; the proposed method gave higher results for two preparations but lower results for the third. In the second study, four types of multivitamin preparations were analyzed; twelve laboratories reported on the chemical methods and three laboratories on the microbiological method. There was no difference in the mean values for two types of samples, but one sample of multivitamin tablets yielded mean values about 5% lower by the proposed method, suggesting the presence of a trace of niacin; with a multivitamin and mineral sirup the proposed method gave values about 6% higher than the AOAC method and 3% lower than the microbiological assay. The coefficient of variation for any sample in any laboratory by the AOAC method was about 14% in the first study and 1 1% in the second study; by the proposed method it was 4 and 9% in the same respective studies. It is recommended that the present AOAC method be modified by adjusting the pH of sample hydrolysates in the range of 2.5—4.5 instead of 7—9 to reduce the absorhance of the blanks, and that the method of Pelletier and Campbell be adopted as official, first action.
Determination of Sugars in Distilled Spirits by GLC
Authors: Martin Glenn E , Eib Nicholas K
Published: February 2020

The anomeric forms of glucose (α and β) and fructose were determined by GLC in both standard solutions and in distilled spirits, using sorbitol as an internal standard. The GLC method for fructose and α and β-glucose compares favorably with the AOAC method for concentrations from about 150 to 225 mg/100 ml. However, at concentrations below 100 mg/100 ml, the GLC method gives generally lower values, probably because the AOAC method measures the amount of reducing sugars and the GLC method measures only α and β-D-glucose and D-fructose
Collaborative Study of the Identification of Grape Varieties
Authors: Rice A C
Published: February 2020

Collaborative studies were conducted on the paper chromatographic method for anthocyanin pigments in Concord grape juice. Six unknowns plus a pure Concord reference sample were submitted to four collaborators with instructions to identify the unknowns as pure or adulterated. All samples were correctly identified by the collaborators. The limit of detection is about 1% (v/v) for California grape concentrates in Concord (or about 5% of the total grape solids present, assuming 68° Brix concentrate and 16° Brix Concord juice). For a color extractive, e.g., Italian grape color (Enocianina), the detection limit is about 1/2% (v/v). The method is recommended for adoption as official, first action.
Collaborative Study of a Polarimetric Method for l-Malic Acid
Authors: Fernandez-Flores Enrique , Johnson Arthur R , Blomquist Victor H
Published: February 2020

A method, utilizing the absorbance of lmalic acid, uranyl acetate complex, modifications of techniques developed by Hartmann for polybasic acids, and changes published by Vandercook, has been developed and collaboratively studied. This newly developed procedure will quantitatively determine l-malic acid in fruit juices, fruit drinks, jellies, and preserves. It is recommended that this method be adopted as official, first action and that application of the method to grape products be studied further.
Determination of Maltol and Ethyl Maltol in Apple Juice by Gas-Liquid Chromatography
Authors: Gunner S W , Hand B , Sahasrabudhe M
Published: February 2020

The qualitative and quantitative analysis of maltol and ethyl maltol in apple juice is described. The compounds were extracted with ethyl acetate and, after the addition of 2,6-dimethoxyphenol as internal standard, they were analyzed by gas-liquid chromatography as such or as their trimethylsilyl derivatives. Recovery of maltol and ethyl maltol was dependent on the method of isolation and ranged from 92 to 97.5% in the method of choice
Oxalate Determination: Analytical Problems Encountered with Certain Plant Species
Authors: Abaza R H , Blake J T , Fisher E J
Published: February 2020

Accurate quantitative determination of oxalate in chemical analyses of edible plants is important because oxalate is a poisonous compound. The traditional KMn04-oxalate reduction-oxidation (Dye) method of analyzing for plant oxalate content presents two problems: (a) Plant pectins are not entirely separated in the determination of watersoluble oxalate and interfere in the oxidation of oxalate; and (b) a brownish-black precipitate containing ferrous iron is precipitated at the same pH as calcium oxalate and the precipitate interferes in determination of both water- and acid-soluble oxalate. Our modification of the Dye method consists of (a) using double-distilled water as the diluting medium, (6) increasing the acidity of the water-soluble oxalate medium after plant digestion to obtain complete removal of pectins, and (c) eliminating the ferrous iron-containing precipitate by filtration. Oxalate in the ferrous iron-containing precipitate is determined as calcium and magnesium salts by atomic absorption spectrophotometry; the value thus obtained is added to the oxalate value from the oxidation- reduction method. An indirect analytic method for oxalate, in which all of the oxalate was precipitated as the calcium salt and then measured by atomic absorption spectrophotometry, proved to be inaccurate
An Evaluation of the Method for the Determination of Added Phosphate in Ham
Authors: Kamm L , Coffin E
Published: February 2020

Different areas along the length of individual fresh pork legs were shown to vary in P factor (phosphorus: protein ratio). This variation, the effect of curing gains, and the fatness of the leg are significant in the determination of added phosphate in cured hams. As a result, it is proposed that added phosphate in ham should be expressed on a fat-free green weight basis
Analytical Profile of Cistern Room Whiskies
Authors: Schoeneman Robert L , Dyer Randolph H
Published: February 2020

In this study, 85 bourbon mash, 10 rye mash, and 17 corn mash cistern room whiskies from 42 different distilleries were characterized by both chemical and physical analyses. Determinations, using official AOAC methods, were made on the volatile components commonly used in characterizing distilled spirits. In addition, gas-liquid chromatography was used to quantitatively determine ethyl acetate, n-propyl, isobutyl and isoamyl alcohols, and a colorimetric procedure was used to determine esters. Characteristics of the present samples are compared to those reported in studies made as early as 1898. Also, a tabulation of the pertinent data on mashing, fermentation, and distillation techniques for each sample is included
Rapid Confirmatory Test for Aflatoxin B1, Using Bacillus megaterium
Authors: Clements Nancy Lowe
Published: February 2020

Growth inhibition of Bacillus megaterium NRRL B-1368. in response to anatoxin B1 provides a simple and rapid technique to supplement thin layer chromatographic identification of aflatoxins. Less than an hour is required to set up the test, and results are obtained after overnight incubation (15—18 hr). The test is sensitive to as little as 1 µg aflatoxin B1.
Collaborative Study of Molecular Weight Determination Applicable to Samples with Molecular Weights Less Than 500
Authors: Ogg C L , Scroggins L H
Published: February 2020

A method for determining molecular weights employing the thermoelectricvapor pressure technique was tested by 13 collaborators. The samples used in the study were benzoic and nicotinic acids, n-hexadecylamine, methylpentadecyl ketone, benzylisothiourea hydrochloride, and sulfanilamide. Data from the six samples were analyzed statistically by Youden's technique for collaborative tests. Most deviation between laboratories was due to random errors; systematic errors were low. Choice of solvent and standard were critical. Methanol was shown to be unsatisfactory as a solvent. It is recommended that the method be adopted as official, first action.
TLC-PJnzyme Inhibition Procedure to Detect Some Carbamate Standards and Carbaryl in Food Extracts
Authors: Wales Patricia J , McLeod H A , McKinley W P
Published: February 2020

The TLC-enzyme inhibition method of Mendoza et al. for organophosphorus pesticides was extended to some carbamates. At the optimum pH (8.32), the minimum quantities detected were: 5 ng carbaryl; 10 ng Banol®; 50 ng Mesurol® and Zectran®; 500 ng Matacil®; and 1 µg Baygon®. Bromine treatment converted the carbamates to compounds with different sensitivities and, sometimes, different migration rates. Carbaryl added to apples, beets, cabbage, carrots, lettuce, raspberries, and poultry meat was extracted and detected by the TLC screening procedure. Spots produced by extracted carbaryl were comparable to those of standards, indicating quantitative recoveries.
Determination of Decoquinate in Feeds
Authors: Stone Loyal R
Published: February 2020

The coccidiostat decoquinate is used in poultry feeds at 0.003%. Its fluorescence in alcoholic solution is greatly enhanced by the presence of calcium, magnesium, or strontium. A method was tested collaboratively in which decoquinate is extracted from feed by shaking with 1% calcium chloride-methanol solution, water and acid are added, and the decoquinate is trans-ferred into chloroform and chromatographed on Florisil to separate interferences. It is eluted with the calcium chloride-methanol and determined by fluorescence measurement. Background interference is negligible. Results by nine collaborators were in good agreement with the formulated drug content of feeds. The method is recommended for adoption as official, first action.
Collaborative Study of Sulfamethazine in Mixed Feeds
Authors: Hill V B
Published: February 2020

A method for measuring sulfamethazine in feeds containing procaine penicillin was studied collaboratively. The drug is extracted with 50% methanol and the azo dyes of sulfamethazine and procaine are formed by the Bratton-Marshall color reaction. The mixed dye solution is shaken with chloroform and made alkaline to remove the procaine dye into the chloroform. An aliquot of the aqueous phase with the drug is reacidified and measured against a standard. Thirteen collaborators obtained good recovery and precision on four samples of feed. Coefficients of variation obtained on the four samples ranged from 1.96 to 5.33%. The method is recommended for adoption as official, first action.
An Unforeseen Problem in the Use of Kel-Paks
Authors: Woodis T C , Brabson J A , Burch W G
Published: February 2020

In Kjeldahl methods for the determination of nitrogen in fertilizers, the digestion temperature must be above 370°C to mineralize the nitrogen in refractory organic compounds such as nicotinic acid. In total nitrogen determinations by the Raney catalyst powder method, temperatures during the digestion step were investigated as a possible cause of occasional low results. Decomposition of the polyethylene envelopes of Kel-Paks in the presence of salts of metallic reductants caused rapid fluctuations and excessive rise in temperature with consequent loss of ammoniacal nitrogen. Complete Kel-Paks can be used without difficulty in methods such as 2.044 (for nitrate-free samples) or 2.045 (salicylic acid) that do not use metallic reductants, but only the contents of the Kel-Paks without the envelopes should be used when Raney catalyst or chromium powders have been used to reduce nitrates.
Gas Chromatographic Analysis of Barbiturates in Pharmaceuticals
Authors: Sibert James L , Fricke Fred L
Published: February 2020

A rapid gas-liquid chromatographic method is described by which barbiturates can be separated, identified, and quantitated. Two columns are used. A 6′ cyclohexanedimethanol succinate column is used for all barbiturates except phenobarbital, which has an excessively long retention time. Phenobarbital is determined on an 18″ cyclohexanedimethanol succinate column with santonin as an internal standard. A comparison is made between the GLC, USP, and AOAC methods for the analysis of barbiturates.
Immunofluorescent Screening for Salmonella in Foods: Comparison with Culture Methods
Authors: Schulte S J , Witzeman J S , Hall W M
Published: February 2020

The sensitivity of an immunofluorescent screening technique was compared to conventional culture methods for Salmonella detection in an examination of 3,991 food samples. The sensitivity of the fluorescent antibody (FA) method was denned as the percentage effectiveness of the FA method for detecting true salmonellae-positive samples when compared with the culture method. Data obtained with an improved polyvalent fluorescein-conjugated somatic antiserum showed an average sensitivity greater than 99% in the analysis of 1,259 food samples.
Collaborative Study of a Quantitative Method for Clostridium perfringens in Foods
Authors: Hall Herbert E
Published: February 2020

The quantitative method published in 1962 for Clostridium perfringens in foods was studied collaboratively on five specimens of beef gravy by six laboratories. Results showed small within-laboratory variations between paired specimens and interlaboratory variations that were judged to be no greater than those expected in an anaerobic plate count procedure. The method is recommended for adoption as official, first action.
Gas Chromatographic Method for Determination of Diethylstilbestrol in Feeds
Authors: Smiley I E , Schall E D
Published: February 2020

A GLC method was developed for the determination of diethylstilbestrol in feeds within the 0.0011–0.0022% range, using dienestrol diacetate as an internal standard. A 10 g sample was extracted with 7% ethanol in chloroform and subjected to a modified alkaline cleanup. The bis-(trimethylsilyl) acetamide derivative was then prepared and determined by GLC. No interference was encountered with commercial feed samples.
Chromatographic Procedure for Determination of Reserpine in Tablets. II. Collaborative Study
Authors: Barkan Susan
Published: February 2020

A method is described for the quantitative determination of reserpine in tablet formulations. A suitable amount of tablet material is triturated with dimethylsulfoxide (DMSO), incorporated onto Celite, and transferred to a chromatographic column containing acid, base, and water layers. The reserpine is eluted with chloroform and quantitated spectrophotometrically. Duplicate results from 16 collaborators averaged 100.7% recovery as determined by UV, 98.8% recovery determined by colorimetric analysis. The method is recommended for adoption as official first action.
Collaborative Study of the Babcock and Foss Milko-Tester Methods for Measuring Fat in Raw Milk
Authors: Shipe W F
Published: February 2020

A rapid test for fat content in fluid milk, based on the measurement of light scattered by fat globules, was studied collaboratively. The Milko-tester instrument, developed by Danish scientists, was used. The milk is homogenized to produce uniformsized fat globules and then diluted with a Versene solution which eliminates the turbidity caused by the casein micelle. The amount of dilutant is adjusted so that the values obtained agree with the reference method being used for calibration. In two collaborative trials involving 6 laboratories and 9 samples, and 5 laboratories and 12 samples, respectively, the standard deviations were ±0.069 and ±0.074 for the Milko-tester and Babcock methods, respectively. The corresponding averages for the 21 samples were 4.70 and 4.69%. The standard deviation of difference between Milkotester and Babcock average values for the 21 samples was ±0.045%.
Comparison of the Dye Binding and Kjeldahl Methods for Protein Analysis of Nonfat Dry Milk and Ice Cream
Authors: Sherbon J W , Luke H A
Published: February 2020

Ten samples of nonfat dry milk and five samples of vanilla ice cream mix were analyzed in quadruplicate in seven laboratories for protein content by the dye binding method. Laboratory and laboratory times sample effects were significant at the 0.5% level but the coefficients of variation were 1% or less. Comparison of average results obtained by dye binding to those obtained by Kjeldahl show the former to have sufficient accuracy. Direct analysis of NFDM was found to give essentially the same results as analysis of the reconstituted product. It is recommended that the dye binding methods for protein in nonfat dry milk and ice cream mix be adopted as official first action.
Acetonitrile Extraction and Determination of Carbaryl in Fruits and Vegetables
Authors: Porter Mildred L , Gajan Raymond J , Burke Jerry A
Published: February 2020

A method of analysis for carbaryl residues in an acetonitrile extract of fruits and vegetables is described. Considerable time is saved by using an aliquot of the extract prepared for the widely used multiresidue analysis. Polarography is used for quantitative analysis; however, cleaned up solutions are also suitable for spectrophotometric or TLC determinations. The proposed method effectively extracts residues of field-incurred carbaryl whereas extraction procedures used in previous methods removed only 60–70% of such residues. Recoveries of 90–112% have been obtained from six fruits and vegetables fortified with 0.2 to 10.0 ppm carbaryl.
Rapid Method for the Extraction of Light Filth from Oregano
Authors: Tekbush L E
Published: February 2020

A method has been developed for the extraction of light filth from oregano which eliminates the petroleum ether defatting and chloroform-carbon tetrachloride heavy filth separation used in method 36.089. Results are comparable to the official method, and analytical time is reduced by one-half. The method is recommended for adoption as official first action.
Atomic Absorption Analysis of Copper and Lead in Meat and Meat Products
Authors: Dalton Edward F , Malanoski Anthony J
Published: February 2020

Atomic absorption spectrophotometric determination of lead and copper in meat products is described. Organic material is destroyed by dry ashing a t 500°C. Copper and lead levels ranged from 1–5 a n d 1–10 ppm, respectively.
Collaborative Study of a Gas Chromatographic Method for Ronnel in Feeds
Authors: Gehrt Albert J
Published: February 2020

A GLC method (flame ionization detector) for ronnel in cattle feeds at levels of 0.038, 0.041, and 0.055% was studied by 11 collaborators. The method involves extraction of ronnel by shaking with acetone followed by direct chromatographic measurement. The method is simple and rapid (no cleanup required), measures true ronnel, and is free from interferences present in the UV methods previously studied. Agreement between laboratories was satisfactory; coefficients of variation were 11.0, 12.0, and 7.2%. Ronnel recoveries were 81.1, 93.5, and 98.0%. Low recovery from the first sample may be due to ronnel hydrolysis or binding during storage (sample was 8 months old). The Associate Keferee recommends that the method be adopted as official first action.
Gas Chromatographic Determination of Methyl Salicylate, Safrole, and Related Compounds in Nonalcoholic Beverages
Authors: Larry Damon
Published: February 2020

As steam distillation GLC method for determining methyl salicylate, safrole, and related compounds in nonalcoholic beverages has been developed and studied collaboratively. Spiked samples of three commercially prepared sirup bases were sent to nine collaborators. Seven components were added at levels from 5 to 80 ppm . Only t he methyl salicylate analysis gave acceptable precision and accuracy at all spiking levels; at the 80 p pm level, the average recovery was 95 ± 5%. It is recommended that the method be adopted as official first action for methyl salicylate and that work be continued on safrole and related compounds.
Colorimetric and Ion-Pair Column Partition Determination of Phenylephrine in Drug Formula
Authors: Margosis Michel
Published: February 2020

The Emerson 4-aminoantipyrine colorimetric reaction as modified by Hiskey and Levin was applied to a number of commercial products containing antibiotics. Acetaminophen and tetracycline were found to interfere.

Four different solutions containing varying known amounts of phenylephrine were submitted to a collaborative evaluation of the Koshy and Mitchner modification of the Emerson reaction, and to the ion-pair column partition method of Levine and Doyle. The results were evaluated statistically. The colorimetric method showed average recoveries of 99.7% for solution 1, 96.1% for solution 2, and 100.7% for solution 3, with a 95% confidence limit of ±1.4, 2.0, and 3.0%, respectively. Average recoveries by the ion-pair column partition method were 84–101% with 95% confidence limits ranging between 10 and 22%. The colorimetric reaction of Emerson as modified by Koshy and Mitchner is recommended for adoption as official first action, but collaborative study of the ion-pair column partition method of Levine and Doyle should be repeated.
Modified Method for Determining Ash in Maple Sirup
Authors: Wendt A S , Flynn C
Published: February 2020

Collaborative study was conducted on a modified ash method, and results compared favorably with those by the official method. The modified method reduced analytical time and gave slightly better precision. The modified method is recommended for adoption as official first action.
Collaborative Study of Enzymatic Glucose Determination in Corn Starch Hydrolysates
Authors: Brady J T , Zagorski J A
Published: February 2020

Glucose in starch hydrolysates was determined by catalytic oxidation of glucose with glucose oxidase to form hydrogen peroxide which, in the presence of peroxidase and a chromogen, yields a colored product. This product, when acidified, is very stable and the color intensity is proportional to the glucose concentration in the sample. Fermco Test S.F.G., a package containing all the ingredients necessary for the reaction, was used. Eleven collaborators who analyzed five different sirup samples found the method to be adequate for determining glucose. Results compared well with those by paper and gas chromatography. The method is recommended for adoption as official first action.
Application of an Automated Coulometric Titrator to the Determination of Water in Phosphoric Acids
Authors: Jordan Donald E , Hoyt Jack L
Published: February 2020

In the described method, water in phosphoric acid is determined by in situ coulometric generation of Karl Fischer reagent with automated end point detection. The variables associated with visual end point detection among different operators are eliminated. Sample size is limited by the generation rate of available coulometers and is 50 mg for samples containing more than 20% water and 100 t o 150 m g for samples containing less than 20% water for a 20 min analysis time . The precision at 99% confidence ranges from 0.43 ± 0.05% for superphosphoric acid to 36.8 ± 0.81% for untreated 10–34–0 base solution; for polished wet process phosphoric acid the precision is 16.49 ± 0.19% compared to 16.70 ± 0.64% by azeotropie distillation. The method is applicable in all systems which do not normally interfere with Karl Fischer reagent; the generating efficiency at the 100% water level is >99%. Coulometer power tube fatigue is the most serious limitation unless a careful check and replacement program is initiated.
Emulsifiers. III. Periodic Acid Analysis for 1-Monoglycerides
Authors: Distler E , Baurs F J
Published: February 2020

Two collaborative studies were conducted to compare the official AOCS method, Cd 11–57, and a revised Miner procedure. The second study used known materials to obtain accuracy information. Studies showed that the revised Miner procedure is more accurate and more precise at low monoglyceride levels such as those encountered in commercial shortenings. It is recommended that the Miner procedure be adopted as official first action. It is further recommended that the joint AOAC-AOCS methods study of these two procedures be continued so that a single common method can be made official by both societies.
Estimation of Nonepoxide Xanthophyll in Sun-Cured and Freeze-Dried Alfalfa, Clovers, and Grasses
Authors: Livingston A L , Nelson J W , Kohler G O
Published: February 2020

Nonepoxide xanthophyll in forage plants was analyzed hy acidifying the xanthophyll fraction obtained by chromatographic purification. The 5,6-epoxy xanthophylls were altered to give their 5,8-epoxy derivatives with shifts in visible spectra of 20–40μ. The nonepoxy xanthophyll was then measured at 475 mμ as lutein equivalents. The procedure was readily applied to sun-cured or freeze-dried alfalfa, clovers, or grasses. Dehydrated alfalfa samples gave the same xanthophyll values by either the nonepoxide method or a previously reported total xanthophyll procedure, due to lower epoxide content and high levels of lutein isomers.
Chromatographic Determination of Caffeine in Instant Tea
Authors: Newton John M
Published: February 2020

An ultraviolet spectropholometric and GLC method for determining caffeine in instant tea utilizes the extraction and cleanup procedures of the official AOAC chromatographic methods for caffeine in APC and in coffee and a KCl thermionic detector. The detector is sensitive to as little as 1 ng caffeine. The method was studied collaboratively in eight laboratories on three instant tea samples. Results were in reasonable agreement, and the method is recommended for adoption as official first action.
Drained Weight Determination of Frozen Alaska King Crabmeat
Authors: Miller George A
Published: February 2020

The drained weight method of the Alaska King Crab Marketing and Control Board and the Werren-Weik drained weight method for frozen shrimp were studied collaboratively for frozen Alaska king crabmeat. An authentic pack of frozen, unglazed king crabmeat, representing three packing practices, was analyzed by 10 collaborators. Recoveries were 96.2 ± 3.3% by the King Crab Board method and 94.6 ± 2.4% by the Werren-Weik method. The Associate Referee recommends that a limited drained weight study be conducted on frozen Alaska king crabmeat with added flood water and glaze to compare the results with the study reported herein.
Key to the Identification of Canned Salmon Species by Scale Characteristics
Authors: Newton Richard T , Burnett James L
Published: February 2020

A key based on characteristic scale patterns has been developed to distinguish the five species of canned salmon. The scales are simply removed from the fish skin, examined under magnification, and keyed as to species. Nine of ten cans of unknown salmon were correctly identified by laboratory personnel unfamiliar with salmon species. The one error was due to inadequate explanation of terms used in the key. It is recommended that the amended key be subjected to collaborative study.
Extraction and Atomic Absorption Analysis of Lead in Plant and Animal Products
Authors: Hoover William L , Reagor John C , Garner Julianne C
Published: February 2020

Samples of plant or animal tissue are digested in a mixture of HNO3, H2SO4, and HClO4. Lead released in the digestion is entrained with strontium sulfate. The sulfate precipitate is separated from the digest and then converted to the carbonate by agitation with ammonium carbonate solution. The carbonate precipitate is dissolved in 1N HNO3, and lead is determined by atomic absorption spectrophotometry. Good recovery of lead (100 ± 3%) was observed except in samples with high calcium content (> 1%). For the latter samples, good recoveries were obtained after separation of the calcium from the digested samples. Moderate quantities of the following elements do not interfere: Al, Fe, P, Sn, Ca, Bi, and Tl. Most elements are soluble as sulfates and, hence, do not interfere. The procedure is rugged. Dry samples containing from 0.5 ppm to 1% lead can be routinely analyzed.
Gas Chromatographic Determination of Chlormadinone Acetate in Cattle Tissues
Authors: Donoho A L , Johnson W S , Koons J R , Scroggs R E
Published: February 2020

The method described will detect concentrations of the progestational steroid, chlormadinone acetate (CA), as low as 0.02 ppm. Muscle, liver, and kidney samples are extracted with methanol, and the CA is partitioned into carbon tetrachloride. Fat samples are dissolved in hexane, and the CA is partitioned into acetonitrile. Muscle, liver, and fat extracts are further purified by silica gel column chromatography. Kidney extracts are purified on alumina columns. CA is measured in benzene by GLC using a 1.5% XE-60 column and electron affinity detection. Recovery of CA in control tissues fortified with 0.05 µg/g was 80–110% in muscle, liver, and kidney and 70–80% in fat.
Thin Layer and Gas-Liquid Chromatography of Cholesterol in Fats and Oils. I. Development of Method
Authors: Thorpe C W , Pohland Linda , Firestone D
Published: February 2020

A inethod is described for analysis of sterols by thin layer chromatography-gas liquid chromatography (TLC-GLC). Sterols are isolated from other components of unsaponifiable matter by preparative TLC. The sterols are quantitatively removed from the TLC plate, extracted from the silica gel, and analyzed by GLC. This method has been used to detect low levels (2–3%) of animal fat in vegetable oil by measuring the cholesterol content of the animal fatvegetable oil admixtures.
Extraction, Separation, and GLC Detection of Silvex and Its Propylene Glycol Butyl Ether Ester in Fish Tissue
Authors: Williams Philip W , Teasley John I
Published: February 2020

A method is described for the quantitative analysis of silvex and its propylene glycol butyl ether ester in fish tissue. A methanolic extraction and gas chromatographic detection yielded recoveries from fortified fish tissue of 80 to 96% at levels of 0.005 to 1 ppm for the ester and 84 to 98% at 0.002 to 1 ppm for the acid. In an additional recovery study, the extraction procedure was monitored with the PGBE ester labeled at the carboxylic carbon (14C). Live fish were exposed to an aqueous environment containing the labeled PGBE ester and were extracted by the procedure. It was found that 95% of the PGBE ester and its degradation products can be extracted from the tissue with methanol.
Analysis of Grains for Multiple Residues of Organic Fumigants
Authors: Malone Bernadette
Published: February 2020

A sweep co-distillation procedure, a published steam distillation procedure, and an adaptation of an established acid reflux procedure for isolating fumigant residues were compared. Residues were detectable by electron capture gas chromatography at levels approaching or surpassing 0.1 ppm. Fumigants used were carbon tetrachloride, carbon disulfide, ethylene dichloride, ethylene dibromide, methyl bromide, and chloroform. Comparison of the three methods, using the same detection for all, showed that acid reflux was the most promising procedure for recovering added fumigants from grain and extracting fumigation residues. This procedure should be further refined.
Gas Chromatographic Determination of Residues of Dalapon in Several Substrates
Authors: Getzendaner M E
Published: February 2020

Methods are described for determining residues of Dalapon in four types of substrates: fresh plant tissues, dry plant tissues not containing oil, dry plant tissues containing oil, and body fluids. After aqueous extraction and partition into diethyl ether, Dalapon is determined by gas chromatography using electron capture detection. Recovery from 22 different substrates averaged 90%. An average of 88% of Dalapon added to 11 crops and stored from 1.5 to 7 years was recovered.
Correlation of Uric Acid Content with Fragment Counts in Insect-Infested Flours and Wheat Grains
Authors: Sen N P , Vazquez Alberto W
Published: February 2020

Seven samples of naturally insect-infested wheat were examined for (a) uric acid content, (b) per cent agricultural damage, (c) whole or equivalent insects, and (d) insect damage as determined by X-ray technique. Thirteen different forms of flours obtained by milling these wheat grains in a Buhler pilot mill were analyzed for uric acid and insect fragment counts. For wheat grains, the correlation between uric acid contents and X-ray data was found to be the best among the six possible intercomparisons. The results for the first break flour samples also indicated good correlation between the uric acid levels and insect fragment counts.
Determination of Moisture in Dried Prunes
Authors: Bolin H R , Nury F S
Published: February 2020

The official AOAC (20.009) and the dried fruit moisture tester (DFMT) methods for determining moisture in dried prunes have been collaboratively studied. Results indicate that there is no significant difference (P > 0.01) between the two method means. A significant difference (P < 0.001) did occur between laboratory means, which reflected individual differences in performing the operations. Results also indicated that the DFMT charts are accurate throughout their temperature range.
Infrared, Ultraviolet, and Visible Spectrophotometric Determination of Imidan in Animal Dips and Sprays
Authors: Czech Fred P , Mack Marvin D , Evans George
Published: February 2020

Procedures utilizing certain regions of spectral energy for the analysis of Imidan in emulsifiable and wettable powder concentrates, aqueous livestock dips, spray dips, and sprays are presented and compared. The UV method is recommended for rapid analysis of proprietary concentrates. IR and colorimetric methods are advised for filth-laden animal dips and sprays. The IR method can be genrerally applied, is entirely specific for Imidan, and is quite precise. The other procedures are particularly useful for determination of low levels of Imidan.
Note on Non-applicability of the AOAC Xanthydrol Test for Urea When Applied to Non-Fat Dry Milk
Authors: Freeman C C
Published: February 2020

The AOAC xanthydrol test for urea has been found to be non-applicable for the analysis of non-fat dried milk because the level of urea naturally occurring in the dried solids interferes.
Fate of Diazinon in Field-Sprayed Agricultural Crops, Soil, and Olive Oil
Authors: Eberle D O , Novak D
Published: February 2020

Residues of unchanged diazinon in agricultural crops, olive oil, and soil are measured routinely by an improved analytical method, using various selective gas chromatographic detector systems. The limit of detectability is 0.01 to 0.02 ppm, using analytical aliquots representing 1 g suhsamples. Possible metabolites with strong cholinesterase-inhibiting activity are detected on TLC plates by fly head cholinesterase inhibition with a limit of detection of 0.002 ppm from 1 g suhsamples. Residues of diazinon dissipate rapidly. Traces of oxodiazinon were detected, but no other cholinesterase- inhibiting metabolites were discovered at any time between application and harvest.
Cyclodiene Chemistry. II. Identification of the Derivatives Employed in the Confirmation of Heptachlor, Heptachlor Epoxide, cis-Chlordane, and frans-Chlordane Residues
Authors: Cochrane W P
Published: February 2020

The effect of strong basic reagents on the title compounds was investigated. The dehydrochlorination of cis-chlordane proceeds rapidly to give 3-chlorochlordene, whereas its isomer, trans-chlordane, loses HCl very slowly to yield 2-chlorochlordene. The difference in rates of HCl elimination and the formation of isomeric chloro-vinyl derivatives is discussed with reference to the mechanisms of the reactions and the structures of the parent compounds. The action of basic reagents on heptachlor epoxide resulted in preferential epoxide isomerization (or rearrangement) to an allylic alcohol derivative. The structure of this α,β- unsaturated alcohol was elucidated from the characterization of the products formed by chlorination and oxidation. Ileptachlor undergoes substitution to give 1-hydroxychlordene in basic hydroxylic media. The addition reactions of tert.-butyl hypochlorite/glacial acetic acid to both heptachlor and aldrin are also mentioned.
Note on a Two-Dimensional Thin Layer Chromatographic Technique for Identification of Pesticide Residues in Troublesome Samples
Authors: Kawatski J A , Frasch D L
Published: February 2020

Pesticide residue samples which have not been cleaned up enough for confirmatory TLC are spotted and developed in two directions on alumina plates. After ascending development with n-heptane, plates are rotated 90° and developed with n-heptane-saturated acetonitrile to separate residue spots from sample interferences.
Interlaboratory Study of Analytical Techniques for Fluorine in Vegetation
Authors: Jacobson Jay S , McCune D C
Published: February 2020

An interlaboratory study of fluorine analyses on plant tissues was performed to determine the current levels of within- and between-laboratory precision. Homogeneous, ground, fluorine-containing leaf tissues of alfalfa, citrus, gladiolus, pine, and orchard grass were analyzed by the routine methods currently in use in 31 different laboratories. Wide differences in results from these laboratories were obtained. Variations in procedures, techniques, and operating conditions probably account for the large relative standard deviations between laboratories, which ranged from 12.7 to 25.4%. The results of duplicate analyses indicated that some laboratories had difficulty in obtaining reproducible results. Greater attention to detail, more careful performance of operations, increased use of check procedures, standardization of techniques, and development and use of referee samples are needed in order to improve agreement within and between laboratories.
Neutron Activation and Atomic Absorption Analyses of Chemical Elements in Soil
Authors: Brunelle R L , Hoffman C M , Snow K B , Pro M J
Published: February 2020

Procedures are described for the determination of about 20 chemical elements in soil by NAA and AAA. It is shown that the combination of these techniques is particularly suitable for soil analysis, because a large number of both major and minor elements can be determined with good precision and accuracy.
Neutron Activation Analysis of Selenium in Biological Samples
Authors: Lambert J P F , Levander O , Argrett L , Simpson R E
Published: February 2020

The selenium content in tissues of rats fed chronically toxic levels of selenium was determined by neutron activation analysis. The results were highly dependent on the value of the 77mSe half-life used in the computations. The best half-life value was selected by comparing results for different values of half-life feith those from a colorimetric determination of identical samples. The neutron activation analysis method is rapid, nondestructive, and free of any chemical procedures. Selenium was determined at a 3 μg level with a counting error of ± 6% at the 95% confidence level.
Dry Ash Spectrophotometric Method for the Determination of Phosphorus in Milk
Authors: Bedessem R V , Alioto P , Moubry R J
Published: February 2020

Magnesium nitrate is added to milk, which is then dry ashed. Phosphorus is determined colorimetrically after reaction with bisulfitehydroquinone and ammonium molyhdate. A standard curve and blank analysis are used in the final calculation. Recoveries of phosphorus averaged 95 to 105%. Results of duplicate analysis are presented to show the precision of the method.
An Automatic Filter Pipet
Authors: Ellis John H
Published: February 2020

A precise automatic pipet has been developed to automate the filtering and aliquoting steps inherent in many chemical analyses. The pipet can be operated as a single unit or in a series; the standard deviation for 10 determinations with a 25 ml pipet was 0.020 and for an array of six 75ml pipets was 0.033.
Comparison of the Automatic Dumas and Kjeldahl Methods for the Determination of Total Nitrogen in Fertilizers
Authors: Morris G F , Carson R B , Jopkiewicz W T
Published: February 2020

Representative N-P-K fertilizers were analyzed for total nitrogen by the automatic Dumas method, using a catalyst-assisted combustion at 900°C, and by the macro Kjeldahl method. The precision and accuracy of both methods were considered to be adequate for this type of material and compared favorably. The automatic Dumas method gave slightly higher results than the Kjeldahl method and a statistical evaluation of the experimental data showed that the Kjeldahl method was generally more precise.
Effects of Washing Technique in the Determination of Citrate-Insoluble and Available P2O5 in Triple Superphosphate
Authors: Harwell W J , Hewitt E B
Published: February 2020

The results of the citrate-insoluble and available phosphorus determinations are influenced by the technique used in the initial step, the removal of the water-soluble fraction. An “active” washing technique in removing all of the water-soluble fraction will give lower values for citrate-insoluble phosphorus and higher values for available phosphorus.
Isolation and Purification of Ochratoxins A and B and Preparation of Their Methyl and Ethyl Esters
Authors: Nesheim Stanley
Published: February 2020

Ochratoxins are extracted with hot chloroform from Aspergillus ochraceus cultures grown on moist shredded wheat breakfast cereal. The chloroform solution is mixed with hexane to precipitate the ochratoxins, which are filtered off and redissolved in fresh chloroform. The ochratoxins are further purified by extraction from the chloroform solution with 0.5Af aqueous bicarbonate and transfer to another portion of chloroform after acidification of the salt solution. Ochratoxins A and B are separated from each other by gradient .silica gel column chromatography, using an acetic acid-benzene cluant; the fractions are analyzed by TLC densitometry. Final purification is by crystallization of ochratoxin A from benzene and ochratoxin B from methanol. The ethyl and methyl esters of ochratoxins A and B are prepared by boron fluoride-catalyzed esterification with ethanol or methanol and are purified by aqueous sodium bicarbonate extraction from a chloroform solution.