bluuebunny/crossref_metadata_2025 huggingface dataset:
Separation and Determination of Trace Amounts of Tin Present as Organotin Residues on Fruits
Authors: Corbin Homer B
Published: February 2020

The dithiol colorimetric method has been applied to the determination of trace amounts of tin as residues from the spray treatment of fruit with a miticide containing tricyclohexyltin hydroxide. The samples are prepared by an initial wet combustion to give a sulfuric acid solution of tin in the inorganic form. The tin is separated from other elements in the acid digest by one of two methods. One involves distillation of stannic bromide with a mixture of HBr and HCl. In the second separation method stannic iodide is extracted into n-hexane. Both separation procedures result in a solution of tin in a few milliliters of concentrated H2SO4, which is then measured spectrophotometrically. Data are presented for sensitivity and precision of the measuring system; accuracy and precision of both separation methods are illustrated by duplicate analyses and recovery tests on apples and pears treated with various cyclohexyltin compounds and inorganic tin. The extraction method has been tested for compatibility with 35 elements. Only arsenic (>0.15 mg or 1.5 ppm) and antimony (>2 mg or 20 ppm) are likely to interfere. Procedures are given for elimination of greater amounts of these elements.
The High Resolution NMR Spectra of Pesticides. III. The Carbamates
Authors: Keith L H , Alford A L
Published: February 2020

The high resolution nuclear magnetic resonance spectra of 35 carbamate pesticides and a major metabolite of one pesticide are discussed. The chemical shifts and coupling constants are tabulated and reproductions of the more complex or unusual spectra are included. A concentration and solvent dependence of both the NH-proton and the NCH3-proton resonances of an N-monosubstituted carbamate is discussed. Hindered rotation is observed in the N,N-dimethylcarbamates, the thiolcarbamates and the dithiocarbamates, but not in the N-methylcarbamates.
Xanthophylls and Carotenes in Feeds and Feed Materials: Collaborative Study
Authors: Quackenbush F W
Published: February 2020

Eight laboratories showed satisfactory agreement in analysis of three pairs of samples (corn gluten, alfalfa meal, and mixed feed) by a proposed method for xanthophylls and carotenes. The method permits separation of monohydroxy pigments from dihydroxy pigments and excludes the non-pigmenting (avian) polyoxy pigments. It is recommended for adoption as official first action.
Collaborative Study of a Rapid Electrophoretic Method for Fish Species Identification. II. Authentic Flesh Standards
Authors: Learson Robert J
Published: February 2020

The cellulose acetate method of fish species identification was collaboratively studied a second time, using authentic flesh samples as standards. Eleven collaborators were asked to identify ten unknown fish samples from a set of nine standard flesh samples. The collaborators identified the unknown samples with 91% accuracy. It is recommended that the method be adopted as official first action.
Collaborative Study on the GLC Determination of Propylene Glycol in Cosmetics
Authors: Margaree H. Champion
Published: February 2020

A method for the determination of propylene glycol in cosmetics by GLC, using Chromosorb 101 as a column packing, was submitted to collaborative study. Four samples were analyzed at two levels of concentration. Results for the six collaborators show recoveries of 95-108% for samples containing from 20.0 to 40.0 mg propylene glycol. The standard deviation varied from 0.54 to 1.67 and the coefficient of variance from 2.8 to 4.7%. It is recommended that the method be adopted as official first action.
Effect of Moisture and Incubation Time on Ochratoxin A Production by an Isolate of Aspergillus ochraceus
Authors: Schindler A F , Nesheim Stanley
Published: February 2020

Experiments were conducted to determine the culture requirements that would insure a probability of high ochratoxin production with a given isolate. Experiments at ambient temperatures (72 ± 2°F) determined the levels of the two most readily controlled variables, time and moisture content, during the growth of a high toxin-producing isolate (M298) of Aspergillus ochraceus. Tests were conducted in 2.8 L - Fernbach flasks containing 100 g shredded wheat and inoculated with spores on a transfer needle. Amounts of ochratoxin A/flask were determined by comparison against standards on TLC after chloroform extraction. Statistical analysis showed a relation between ochratoxin yield, water levels, and incubation periods. A water level of 40–70 ml/flask with an incubation period of 19-21 days at ambient temperatures should give a near to maximum yield of ochratoxin A.
Drained Weight Determination of Frozen Alaska King Crabmeat
Authors: Miller George A
Published: February 2020

A limited collaborative study is presented which evaluated two methods for drained weight of Alaska king crabmeat: the Alaska King Crab Marketing and Control Board method and the Werren-Weik drained weight method for shrimp. One variable concerning the effect of added flood water and surface glazing of frozen cut units was studied by both methods. Four collaborators, two performing determinations according to each method, reported average recovered drained crabmeat in close agreement with results reported previously. Both methods are recommended for adoption as official first action for frozen glazed Alaska king crabmeat.
Application of Atomic Absorption Spectroscopy to Pharmaceutical Analysis
Authors: Leaton J R
Published: February 2020

Procedures are described for analysis of minerals and element-containing drugs in various pharmaceutical preparations by atomic absorption spectroscopy. Sample preparation of liquids, powders, tablets, and ointments is reduced to a minimum by employing the technique of acid-dissolution and a releasing agent of lanthanum chloride. There are little or no elemental interferences or losses as shown by high recoveries and low standard deviations. Recoveries from commercial preparations ranged from 94 to 106% of theory or declared amount. Guidelines and operating instrumental conditions are given.
Absorptivity and Solid State and Solution Fluorescence of Mixed Aflatoxin Standards Stored in Solution and as Dry Films
Authors: Pons W A , Robertson J A , Cucullu A F , Goldblatt L A
Published: February 2020

Mixed anatoxin B1, B2, G1, and G2 standards were stored 1 year in chloroform and benzene solutions and as dry films at 28 and – 18°C. Weighted average molar absorptivity and solution and TLC plate fluorescence were used as indices of deterioration. Changes in all three indices were greater for standards stored at 28°C than for those stored at –18°C. Storage at 28°C resulted in appreciable deterioration of dry film standards. Both solution and plate fluorescence were more sensitive indices than molar absorptivity for detecting changes in the properties of stored standards. A good correlation was obtained between anatoxin concentration as measured by UV molar absorptivity and the plate fluorescence of the stored standards. An accelerated storage study of anatoxins B1 and G1 stored 34 days in benzeneacetonitrile (98 + 2) at 51°C showed no detectable change in molar absorptivity or plate fluorescence.
Rapid Colorimetric Method for Estimation of Thiram Residues on Grains
Authors: Rangaswamy J R , Poornima P , Majumder S K
Published: February 2020

A rapid and relatively simple method has been developed for the colorimetric determination of thiram residues on grains. Cuprous chloride is used to form a yellow complex with thiram, which is measured at 420 nm. The method is satisfactory for analyses of 4–200 Mg thiram.
GLC Determination of Hexachlorophene in Several Agricultural Samples
Authors: Gutenmann W H , Lisk D J
Published: February 2020

A method is described for analysis of the fungicide hexachlorophene in agricultural samples after cleanup on a Celite-H2S04 column. It is based on electron affinity gas chromatography of the methyl ether and is sensitive to about 0.02 ppm of the fungicide. The procedure has been applied to analysis of hexachlorophene in tomatoes, sweet corn, cucumbers, and milk.
Microbiological Assay of Vitamin He and Its Components
Authors: Toepfer Edward W , Polansky Marilyn M
Published: February 2020

Nine collaborators studied a method for determining vitamin B6 and pyridoxine, pyridoxal, and pyridoxamine in foods and like materials. The 3 vitamin B6 components in food extracts were eluted in separate fractions from an ion exchange column and determined separately by microbiological assay, using the yeast S. carlsbergensis as the test organism. It is recommended that the method be adopted as official first action.
Extraction of Light Filth from Corn- and Rice-Based Ready-to-Eat Breakfast Cereals and Corn-Based Snack Foods
Authors: Dent Russell G , Roaf Andree L , Brickey Paris M
Published: February 2020

Collaborative results are presented on a proposed method for light filth extraction from corn- and rice-based ready-to-eat breakfast cereals and corn-based snack foods. Samples are digested with hydrochloric acid, followed by wet sieving on a No. 230 mesh plain weave sieve. Sieve retainings are boiled in 40% isopropanol and filth is extracted in either a Kilborn funnel or a trap flask. Average per cent recoveries of spiked elytral fragments and rodent hairs were 91.0 and 80.0% (using trap flask) and 86.1 and 81.7 (using Kilborn funnel), respectively. The method is recommended for adoption as official first action.
Cautionary Note Concerning Color Stability in Reineckate Salt Analyses
Authors: More Carl A , Kenner C T
Published: February 2020

The absorbance of solutions of reineckate salts in acetone or in aqueous acetone varies with time. Procedures should be modified so that absorbance measurements are made as soon as possible after dissolving the salt and so that the time lapse between solution and measurement is uniform for all samples and standards . The effect of time and temperature of precipitation on the absorbance of the reineckate salts of betaine, choline chloride, and homatropine methylbromide is shown.
Ochratoxins A and B Confirmation by Microbiological Assay Using Bacillus cereus mycoides
Authors: Broce Domiciano , Grodner Robert M , Killebrew Rosamond L , Bonner Frances L
Published: February 2020

TLC identification of presumptive ochratoxins A and B can be supplemented with overnight results obtained by a single and rapid bioassay of these toxins, using Bacillus cereus mycoides LSU as the test organism. Furthermore, this bioassay can provide an accurate quantitative estimation of ochratoxins. The calculated coefficient of variation was 5.9%. The optimal medium, conditions, and ochratoxin concentrations for this assay are suggested. This test is sensitive to as little as 1.5 and 3.0 µg ochratoxins A and B, respectively.
Methodology for Chlorinated Aromatics in Fats, Oils, and Fatty Acids
Authors: Ress John , Higginbotham G R , Firestone David
Published: February 2020

The official first action electron capture GLC (EC-GLC) method for chick edema factors (polychlorodibenzo-p-dioxins) has been reviewed. This general procedure, which was collaboratively studied in 1967, has undergone several minor modifications which result in better recoveries of polychlorodibenzo-p-dioxins and increased specificity in interpretation of the gas chromatographic results. The EC-GLC method can be used as a screening test or, where a typical pattern of GLC peaks is obtained, as a preliminary test, but confirmatory tests are needed to demonstrate structure and toxicity of polychlorodibenzo-pdioxins. Preliminary work with combined GLC-mass spectrometry indicated that this technique might provide a suitable test, if adequate sample cleanup can be accomplished. A chicken embryo assay has been developed to the point where toxicity can be observed 3–5 days after injection of eggs. A preliminary procedure has been developed for isolation and gas chromatography of chlorophenols in fats and fatty acids. Polychlorophenols have been found to be precursors of chlorodibenzo-pdioxins. A nonspecific microbiological test for chlorophenols, employing Bacillus megaterium, was evaluated. Chlorophenols were found to produce uniformly graded growth inhibition of the test organism in the range 1–100 µg.
Collaborative Study of Methods for Determination of Ronnel in Feeds and Mineral Mixtures
Authors: Gehrt Albert J
Published: February 2020

A GLC method (electron capture detector) for ronnel in cattle feeds at the 0.040% level and a UV method for ronnel in mineral mixtures (1–40% ronnel) were studied by 9 collaborators. Ronnel is extracted from feed by shaking with acetone, followed by direct GLC measurement. The method is simple and rapid and the electron capture detector is much more sensitive and gives cleaner ronnel measurements than the flame ionization detector used last year. Agreement between laboratories was good; coefficients of variation were 7.7, 7.1, 11.1% with ronnel recoveries of 95–100%. Analyses of feed samples after storage (several months) showed decreases in ronnel, found to be due to partial ronnel binding. Ronnel is extracted from minerals with methanol, followed by UV measurement. The coefficient of variation was 5.4%. The Associate Referee recommends that the mineral method be adopted as official final action and that the feed method be continued as official first action for 1 more year. An investigation of the binding effect is continuing.
Subsidiary Colors in FD&C Green No. 3
Authors: Stein Charles
Published: February 2020

The principal subsidiary colors in commercial FD&C Green No. 3 are identified. There are 2 principal subsidiary colors; one color is formed by the loss of one sulfonic acid group from FD&C Green No. 3 and the second color is formed by the loss of one sulfonated benzyl group from FD&C Green No. 3.
Analysis and Chemical Confirmation of Patulin in Grains
Authors: Pohland A E , Allen R
Published: February 2020

A method is described for the quantitative estimation of patulin in corn, wheat, rye, oats, and sorghum. The procedure involves extraction of the grain with acetonitrile-hexane ( 4 + 1 ) followed by further cleanup through preparative TLC. The patulin concentration is estimated using quantitative TLC on Mallinckrodt 7GF fluorescent plates by comparison with a pure patulin standard. The lower limit of detection in corn by this method is about 40 μg/kg. A chemical confirmatory test involving formation of the phenylhydrazone derivative is described.
Stability Studies with Patulin
Authors: Pohland A E , Allen R
Published: February 2020

The chemical stability of patulin in a variety of foods and feeds in various solvents and in the presence of SO2 in water was investigated spectrophotometrically. Patulin was found to be completely stable in apple juice and dry corn; however, in wet corn, Durham wheat, and sorghum and in the presence of SO2 in water, patulin was observed to be unstable. Patulin was completely stable over long periods of time in chloroform, benzene, and methylene chloride, but slow decomposition was noted in methanol and water.
Detection of Clostridium botulinum and Its Toxin in Food. I. Detection of Clostridium botulinum Type E in Smoked Fish
Authors: Kautter Donald A , Lilly Timothy
Published: February 2020

One mg trypsin/ml is incorporated into an enrichment medium to improve the detection of Clostridium botulinum type E. The procedure was evaluated using smoked whitefish chubs as well as other kinds of smoked fish inoculated with small numbers of spores of C. botulinum types A, B, and E. A greater number of positives was obtained for all smoked fish inoculated with type E spores when this medium was used for enrichment. In addition, by the use of this medium at 26°C for 5 days, proteolytic C. botulinum types A and B can also be detected. Collaborative study is recommended.
Detection of Wheat Grains Contaminated with Urine
Authors: Thrasher Joel J
Published: February 2020

The official method for urine-contaminated grains, 36.109, has an inherent weakness because of the lack of total contact between the test object and the test paper. The modified method virtually eliminates this weakness by embedding the grain in a soft agar containing urease and bro mo thymol blue; the sensitivity is about 2.5 μg urea distributed over a grain of wheat. This is comparable or slightly better than that for 36.109; however, the chances of detection of random spots is better than the AOAC method because of the total contact of the test object with the test medium.
Determination of 2-Chloroethylphosphonic Acid in Apples, Cherries, Onions, and Pineapple Pulp
Authors: Bache Carl A
Published: February 2020

A method for the determination of the growth regulator, 2-chloroethylphosphonic acid in apples, cherries, onions, and pineapple pulp is described. The samples are mascerated and extracted with methanol. The residue is methylated under acid conditions and analyzed by gas chromatography with a alkali thermionic detector. Recovery data are presented at 0.1 and 0.12 ppm. The method is sensitive to about 0.05 ppm.
Analysis of p,p’-DDT and p,p’-DDE Pesticide Residues by Nuclear Magnetic Resonance Spectroscopy
Authors: Biros Francis J
Published: February 2020

Nuclear magnetic resonance spectroscopy has been utilized for semiquantitative analysis and confirmation of mixtures of p,p’-DDT and p,p’-DDE. Several known mixtures have been analyzed as well as pesticide residues isolated from human adipose tissue of an occupationally exposed individual and animal liver tissue from rats dosed with p,p’-DDT. The relative error found for the mole fractions of p,p’-DDT and p,p’-DDE in standard mixtures of these materials ranged from 0.5 to 4.1%, depending on the relative concentrations of pesticides present. Gas chromatographic analyses performed on the tissue extracts by electron capture and electrical conductivity detection agreed well with the results obtained by nuclear magnetic resonance.
Cyclodiene Chemistry. IV. Assignment of Configuration of Two Nonachlors via Synthesis and Derivatization
Authors: Cochrane W P , Forbes M , Chau A S Y
Published: February 2020

The configuration of nonachlor, mp 128- 130°C, was elucidated, from both the structure of its dehydrochlorinated product and the synthesis of stereoisomeric nonachlor, as possessing a l-exo,2-endo,3-exo (i.e., trans-nonachlor) chlorine arrangement in the cyclopentane ring. Dehydrochlorination of transnonachlor yields 1,2-dichlorochlordene, the structure of which was established by specific allylic dechlorination to 2-chlorochlordene. Further confirmation was obtained by conversion to l-keto-2-chlorochlordene. An alternative synthesis of this chloroketone from 1-ketochlordene is described. An isomeric nonachlor, mp 214-215°C, with the l-exo,2-exo, 3-exo (i.e., cis-nonachlor) chlorine arrangement was prepared from a heptachlor chlorohydrin of known configuration. Dehydrochlorination of cis-nonachlor gave 1,3-dichlorochlordene. The reactions of these 2 nonachlors with base is discussed with reference to cisand trans-chlordane.
Note on Cold Bath with an Immersible Stirring Assembly for Low Temperature Precipitation of Fat
Authors: Latham S D
Published: February 2020

The feasibility of an immersible stirring assembly was investigated for use in the precipitation of fat at low temperatures. Precipitations of this type are useful in cleanup procedures for the determination of pesticide residues.
Chromatographic Separation and Spectrophotometric Analysis of a Multicomponent Drug Formulation Containing Methylene Blue
Authors: Woodson Albert L
Published: February 2020

Methylene blue, methenamine, phenyl salicylate, benzoic acid, atropine sulfate, and hyoscyamine are separated by chromatographic procedures. Assays are described for each component. Phenyl salicylate, benzoic acid, atropine, and hyoscyamine are isolated by partitition chromatography on acid- and base-Celite columns. These isolated components are quantitated by ultraviolet spectrophotometry (phenyl salicylate and benzoic acid) and visible spectrophotometry (total alkaloids as atropine sulfate). Methenamine is separated and quantitated by GLC on a column of 6% Carbowax 20M on 80–100 mesh Gas Chrom Q. Methylene blue is quantitated by visible spectrophotometry without prior separation. The data obtained with a synthetic mixture and 3 commercial samples are presented.
Methods for Some Alkaloids, Barbiturates, and Combinations. I. Review of Selected Methods and Development of an Ion Exchange Method for Ephedrine Sulfate or Amphetamine Sulfate Alone or Combined with Barbiturates and Antihistamines
Authors: Smith Donald J
Published: February 2020

Procedures such as steam distillation and partition, column, and ion exchange chromatographic techniques are reviewed for the separation and isolation of selected alkaloids, barbiturates, and combinations; acid titration, colorimetry, and UV spectrophotometry were the usual determination techniques. An ion exchange method, involving both a cation and an anion exchange column, was developed for combinations of amines and barbiturates: amphetamine sulfate or ephedrine sulfate alone or combined with barbital sodium or phenobarbital and pyrilamine maleate, methylpyrilene HCl, or tripelennamine citrate. Preliminary studies with laboratory-prepared and commercial preparations showed good recoveries, with no interference from the commonly used excipients.
Dye Binding Method for Protein Content of Dairy Products
Authors: Sherbon J W
Published: February 2020

The Udy dye binding method for protein in milk has been under collaborative study since 1965. The test is based on the formation of an insoluble complex between Acid Orange 12 (C.I. 15970) and basic amino acid residues of the protein. A known amount of dye is added to the sample, the complex is removed, and the excess dye is measured by colorimetry. The amount of protein in the original sample is calculated from the amount of dye used in complex formation. In previous reports, it was reported that the interlaboratory coefficient of variation is 1% or less, i.e., 0.03% protein in the sample. The coefficient of variation for the Kjeldahl method is 3%. Suitable analytical control is achieved through optical determination of dye concentration in the reagents and by testing known milks. Mercuric chloride is a suitable sample preservative, but potassium dichromate decolorizes the dye. It is recommended that this method be adopted as official final action for determining protein contents of fluid milk, half-and-half, nonfat dry milk, ice cream mix, chocolate drink, and buttermilk.
Comparison of Florisil and ChromAR Sheet Cleanup Procedures on Spinach Extracts for Multiple Chlorinated Pesticide Residues Analysis
Authors: Beasley Thomas H , Ziegler Howard W
Published: February 2020

An improved cleanup procedure for fresh spinach extracts, using silicic acid-glass fiber sheet, was compared directly with the activated Florisil column procedure. The new cleanup method requires about one-half the time necessary for the Florisil column method. The pesticide concentrates were analyzed by quantitative GLC, using a 2’ column of OV–17 and a 90Sr detector. Recovery experiments on 100 g samples fortified with 4 major chlorinated pesticides showed the 2 methods to be comparable.
Volatility of Technical Chlordane: An Alternative Approach for Quantitative Measurement of Residues
Authors: Thompson Don W
Published: February 2020

Volatility studies on technical chlordane under normal laboratory conditions of temperature and fluorescent lighting indicate that only the contribution of trans- and cis-chlordane to the total mixture remains fairly constant. Using this approach, an alternative method of calculation has been evaluated for chlordane residues. Calculation of residues by comparison of GLC peaks for total trans- and cischlordane results in values within ±5% of those calculated from the total area, after correction for a uniform high bias.
Quantitative Determination of Chromium in Triphenylmethane Color Additives by Atomic Absorption Spectroscopy
Authors: Moten Lueangier
Published: February 2020

Trace amounts of chromium (0–60 ppm) in triphenylmethane color additives can be determined rapidly and precisely by atomic absorption techniques on a 5% aqueous solution of the color additive. The effect was determined of several sample-to-sample variations in composition that would be encountered in the routine analysis of these color additives for chromium by atomic absorption. The data show that it should be possible to determine chromium in these color additives at 5 ppm by atomic absorption spectroscopy.
Collaborative Study on Ashing: 1969
Authors: Kowalczuk Joseph
Published: February 2020

A collaborative study evaluated the effect of wet vs. dry ashing on the atomic absorption determination of calcium, iron, magnesium, manganese, and zinc in feeds. Ten laboratories analyzed 6 samples. The high relative standard deviations indicate that ashing methods should be further studied.
An Indirect Chelometric Method for Sulfate
Authors: Woodis T C , Johnson F J , Cummings J M
Published: February 2020

Sulfate is determined rapidly and reliably by precipitation with a measured excess of a lead salt and titration of the excess lead with ETDA. Interfering ions, including phosphate, are removed with ion exchange resins.
Detection of Mold Contamination in Corn by Optical Measurements
Authors: Birth Gerald S , Johnson Robert M
Published: February 2020

A nondestructive technique has been developed for detecting mold contamination in individual kernels of corn by fluorometry based on the fact that the fluorescence from the kernel is quenched or reduced on mold-contaminated corn. Four optical properties (total fluorescence and the spectral characteristics of fluorescence, transmittance, and reflectance) were measured in an exploratory test. The test samples consisted of 10 mold-contaminated (slight to severe contamination) and 10 sound corn kernels. The optical measurements were compared to determine which technique would be most effective in distinguishing between sound and mold-contaminated corn. The best criterion of mold contamination in corn kernels was the ratio between 2 measurements of the fluoresced energy (at 442 and 607 nm). The results indicated that the contaminated kernels could be distinguished from the sound ones with less than 5% error.
Contamination Control in Infrared Microanalysis
Authors: Chen Jo-Yun T , Dority Roland W
Published: February 2020

Sources of contamination are identified in infrared microanalysis of chemical isolates, and means of control are discussed. Infrared spectra illustrating typical examples of contamination are presented.
Determination of Vanadium by Neutron Activation Analysis at Nanogram Levels to Formulate a Low-Vanadium Diet
Authors: Lambert J P F , Simpson R E , Mohr H E , Hopkins L L
Published: February 2020

Neutron activation analysis for vandium is very sensitive if it is combined with a rapid and efficient chemical separation. A postirradiation solvent extraction with N-phenylbenzohydroxamic acid reagent was evaluated by adding known amounts of vanadium to water. When 3.2 to 80 ng were added, the recovery ranged from 97 to 104%. The counting error at the 95% confidence level varied from 10% for 3.2 ng to less than 2% for 80 ng. The time of separation, interferences, and chemical yield which influence sensitivity are discussed. From data obtained in an animal diet survey, a low-vanadium diet with 14 ppb of vanadium was formulated.
Determination of Zinc in Stock and Mixed Feeds by EDTA Extraction and Atomic Absorption Spectrophotometry
Authors: Tuŝl Jax
Published: February 2020

Zinc was extracted from various stock and mixed feeds by EDTA and then determined by atomic absorption spectrophotometry. The EDTA extraction was found to be almost as effective as the standard HNO3-HCIO4 digestion, but it was easier and more rapid. The method was preferable to dry ashing because considerable losses of zinc often occur in the latter method when animal feeds are analyzed.
Studies on the Analysis of Hexachlorobenzene Residues in Foodstuffs
Authors: Taylor Ian S , Keenan F P
Published: February 2020

Analysis of HCB residues in the parts per billion range in cereals is hampered by interference from grain lipids. In fatty foods, analysis using solvent countercurrent extraction is made difficult by unfavorable distribution. HCB is not readily separated from other pesticides by GLC. These difficulties are discussed and partly resolved. Procedures are suggested for the extraction, steam distillation, and alkaline degradation of HCB as possible solutions to the analysis of HCB residues.
A Method for Detection of Aflatoxins B1 and B2 in Toasted Cottonseed Meal
Authors: Yin Lillian , Campbell A D , Stoloff Leonard
Published: February 2020

The detection limit for aflatoxins B1 and B2 in toasted cottonseed meal by the presently accepted analytical method is about 1000 μg/kg. A procedure that reduces the limit to about 5 μg/kg is described. The sample is extracted with aqueous acetonitrile and n-hexane. Interferences are removed from the acetonitrile phase of the extract by precipitation with lead acetate, liquid-liquid partition with water/acetonitrile-chloroform, and silica gel column chromatography. Aflatoxins B1 and B2 in the extract can be separated from the residual interfering fluorescent materials by two-dimensional TLC. This procedure is qualitative only and is capable of detecting aflatoxin B1 or B2 in toasted cottonseed meal contaminated with amounts down to 5 gg/kg of either aflatoxin. Loss of aflatoxin B1 on toasting naturally contaminated cottonseed is observed. When toasting is carried out at 180-185°C for 3 hr, almost complete loss of aflatoxin B1 and partial loss of aflatoxin B2 are observed by means of the procedure described.
Modification of the Assay for Neomycin in Feeds
Authors: Williams B J , Wornick R C
Published: February 2020

The AOAC method for the microbiological assay for neomycin in feeds was modified by preparing the base and seed agar to contain 0.05M tris (hydroxymethyl) aminomethane buffer at pH 8.0 and deleting the addition of the calcium chloride. A 3-fold increase in sensitivity and a dramatic increase in zone definition and clarity resulted. Non-buffered plating medium is acidified in situ by the fermentative activities of the assay microorganism. It is believed that the buffered medium improved the assay by resisting the in situ changes in pH. It is recommended that the modification be subjected to collaborative study.
Colorimetric Determination of Carbaryl in Wettable Formulations
Authors: Vonesch Eugenio E , de Riveros Maria H C K
Published: February 2020

A rapid colorimetric method is described for the determination of carbaryl in technical products and wettable formulations, based on the reaction of carbaryl with diazotized 2,5-dichloroaniline. This reaction is sensitive to 0.1 μg, with a detection limit of 0.2 ppm. Recoveries of pure carbaryl were excellent and analyses of technical products were reproducible.
Behavior of Chlorinated Naphthalenes in Analytical Methods for Organochlorine Pesticides and Polychlorinated Biphenyls
Authors: Armour Judith A , Burke Jerry A
Published: February 2020

Chlorinated naphthalenes are industrial chemicals with properties similar to those of polychlorinated biphenyls (PCB); they are recovered from foods by analytical methods for multiple residues of organochlorine pesticides. The chlorinated naphthalenes may interfere with the gas chromatographic determination of several organochlorine pesticides. A silicic acid column chromatographic method previously developed to separate PCB from organochlorine pesticide residues, particulary DDT and its analogs, also separates chlorinated naphthalenes from the pesticides and permits GLC determination without interference.
Determination of Mercury in Food Products and Biological Fluids by Aeration and Flameless Atomic Absorption Spectrophotometry
Authors: Thorpe Virginia A
Published: February 2020

This paper describes a simple, rapid modification of a method developed at the Fisheries Research Board of Canada for determining mercury in fish and other food products. Wet digestion and flameless techniques of atomic absorption spectrophotometry are used. Replicate analyses on different days showed good precision and samples spiked with known amounts of mercury showed adequate recovery.
Rapid Technique for Solvent Removal in the Determination of Fat
Authors: Cohen Edward H
Published: February 2020

A rapid technique for solvent removal in the determination of fat is described. The official 60 min procedure is reduced to 4-10 min by the use of a nitrogen gas manifold and an aluminum cooling chamber. The precision of the technique is found to be as acceptable as the official method.
Determination of Pure Color in Commercial Samples of D&C Red No. 30
Authors: Hobin Nancy Kay
Published: February 2020

This paper describes the preparation of a pure sample of D&C Red No. 30 (6,6′-dichloro-4,4′-dimethyl-[Δ2,2′(3H 3H′)-bibenzo[b]-thiophene]-3,3′-dione), the determination of the spectrophotometric properties of solutions of the purified sample in xylene, and the modification of a procedure previously described by Stein and Freeman. The modification is considered an improvement, since it requires less time per analysis.
Steam Distillation Technique for the Analysis of 2,3,7,8-Tetrachlorodibenzo-p-dioxin in Technical 2,4,5-T
Authors: Storherr R W , Watts R R , Gardner A M , Osgood T
Published: February 2020

Technical 2,4,5-T formulations may contain 2,3,7,8-tetrachlorodibenzo-p-dioxin as a contaminant. A method is described in which the tetrachlorodioxin is separated from technical components by steam distillation and analyzed by microcoulometric GLC.
Quantitative Determination of Sorbic Acid in Cheddar Cheese by Gas-Liquid Chromatography
Authors: LaCroix D E , Wong N P
Published: February 2020

A rapid method is described for the extraction and quantitative determination of sorbic acid in Cheddar cheese. Cheddar cheese is impregnated onto a Celite 545 column, extracted with acetonitrile, and analyzed for sorbic acid by gas-liquid chromatography, using a 7.5% ethylene glycol adipate + 2% H3PO4 column. Average recovery values for known amounts of sorbic acid were 107%.
Atomic Absorption Adaptation of the Quinolinium Molybdophosphate Method for Phosphorus
Authors: Melton James R , Hoover William L , Howard Peggy A , Green Vera S
Published: February 2020

A method employing a modification of the quinolinium molybdophosphate method is proposed whereby total phosphorus may be indirectly determined by atomic absorption of molybdenum. Only routine instrumentation procedures are required. The official gravimetric method is followed until the quinolinium molybdophosphate precipitate is formed. The precipitate is dissolved in NH4OH, and molybdenum is determined by atomic absorption. Phosphorus analyses of Magruder collaborative fertilizer samples determined by the AOAC and proposed methods compare favorably.
Semiquantitative Determination of Polychlorinated Biphenyls in Tissue Samples by Thin Layer Chromatography
Authors: Mulhern Bernard M , Cromartie Eugene , Reichel William L , Belisle Andre A
Published: February 2020

A method is described for the analysis of polychlorinated biphenyl (PCB) compounds in tissue samples. Cleanup by hexane-acetonitrile partitioning and Florisil column chromatography are performed on samples before oxidative treatment to convert DDE to DCBP. PCB components are then determined semi-quantitatively by TLC. No prior separation of PCB from chlorinated pesticides is required. The lower limit of sensitivity is 0.2 μg.
Semiautomated Liquid Chromatographic Determination of Clopidol in Poultry Feed
Authors: Skelly N E , Cornier R F
Published: February 2020

A semiautomated ion exchange-ultraviolet procedure has been developed for the determination of clopidol in poultry feed at the 40–250 ppm level. A methanol extract of the feed is injected into an alumina precolumn to remove interferences. The clopidol passes through the alumina column and is collected on an ion exchange column. With a specially designed elution apparatus the clopidol is removed by an acetic acid-methanol gradient. The eluate proceeds through a flowcell mounted in an ultraviolet spectrophotometer. Response of the spectrophotometer is monitored by a recorder. Concentration is determined by comparing the peak area in the resulting chromatogram with that of a standard. Accuracy and precision of this method are ±5% relative to the amount present (100±5 ppm).
An Alternative Method for Dispersing Cocoa Press Cake Prior to Light Filth Analysis
Authors: Brickey Paris M , Gecan John S
Published: February 2020

A rapid alternative method has been developed for dispersing cocoa press cake in preparation for light fdth analysis. The press cake is broken into pieces one-half inch or smaller and mechanically stirred in hot (150°C) peanut oil for dispersion prior to defatting with Triton X-114. Light filth is then determined by method 40.006(a). Intralaboratory studies proved the method to be faster than the existing dispersion procedures and to result in almost twice the recovery of rodent hairs. Recoveries of insect fragments were not affected. The method has been adopted as an alternative to dispersion techniques in 40.006(c).
Collaborative Study of a New Method for the Extraction of Light Filth from Water-Insoluble Candies
Authors: Gecan John S
Published: February 2020

A new method has been developed for the extraction of light filth from candies containing water-insoluble ingredients. The candy is dispersed and defatted with a synthetic detergent, wet sieved, deaerated, and extracted with either mineral oil or a mineral oil-heptane mixture from either hot or cooled 40% isopropanol. Collaborative study demonstrated that the new method gives better and more reproducible light filth recoveries and cleaner extraction papers than the official AOAC method. The method has been adopted as official first action to replace 40.081(c).
Collaborative Study of a New Method for Extraction of Light Filth from Reconditioned (Coarsely Ground) Nutmeg
Authors: Vazquez Alberto W
Published: February 2020

A new method has been developed for extraction of light filth from coarsely ground nutmeg. Nutmeg tissue is defatted by 3 successive 10 min extractions with boiling CHCI3, after which the solvent is removed by aspiration and an isopropanol rinse. Following sieving on a No. 230 sieve and a brief deaeration and hydrolysis step in acidified boiling 60% ethanol-CaCl2, light filth elements are extracted with mineral oil from the 60% ethanol-CaCl2 mixture. Collaborative testing of the proposed method yielded satisfactory recoveries of added light filth elements. The official method for ground spices, 40.106(b), was compared in a collaborative study with the proposed method for the analysis of ground nutmeg and mace. Results were encouraging, but further study is indicated. The method as described for reconditioned nutmeg has been adopted as official first action.
Collaborative Study of the Determination of Menadione Sodium Bisulfite in Injections
Authors: Johnson Roger D
Published: February 2020

A chromatographic-UV spectrophotometric method for the determination of menadione sodium bisulfite was subjected to a collaborative study. A sample of the injection is mixed with Celite and placed on a chromatographic column. The column is washed with chloroform; the menadione is eluted with an ammonia-saturated chloroform solution and determined by measuring UV absorbance at 334 nm. Four synthetic sample solutions were sent to 13 collaborators for analysis. The average recoveries of these solutions ranged from 97.5 to 98.4% of added amount and had coefficients of variation ranging from 1.1 to 1.4%. The method has been adopted as official first action.
Detection of Animal Fats in Vegetable Fats and Oils by GLC and TLC
Authors: Thorpe Charles W
Published: February 2020

Three methods which employ digitonin precipitation to isolate sterols were tested to determine the extent to which the digitonides were formed at 3 different mole ratios of digitonin to cholesterol. The effect of added aluminum chloride was also studied. Small amounts of added aluminum chloride reduced the amount of non-complexed cholesterol found by each of the methods studied; however, a minimum weight ratio of 10:1 digitonin to cholesterol is necessary for quantitative work. Two types of commercially available precoated thin layer chromatographic plates were evaluated for use in the present AOAC method for determining animal fats in vegetable fats and oils, 28.018–28.088. Commercial plates were tested with samples identical to those used in the 1969 collaborative study of this method. Results indicate that these commercial plates are acceptable in that they adequately separate sterols from other unsaponifiable components. The official first action method has been revised to permit optional use of these plates.
Collaborative Study of a Gas Chromatographic Method for the Analysis of Diazinon
Authors: Murphy R T , Hofberg A H , Buser H R
Published: February 2020

A gas chromatographic method for the determination of Diazinon in liquid formulations containing about 50% active ingredient was collaboratively studied, using a matched pair scheme. The sample was dissolved in acetone containing aldrin as an internal standard and chromatographed on silicone DC-200, using a flame ionization detector. Determinations on the 2 samples by 18 collaborators using peak height measurements show an overall coefficient of variation of 1.0%. The coefficient of variation of random error is 0.8%, and for the systematic error, 0.4%. Application of the F-test proved this systematic error not to be significant. The method has been adopted as official first action.
Gas Chromatographic Determination of N-Butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine and α,α,α-Trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine in Formulations
Authors: Fuzesi Martha
Published: February 2020

A gas chromatographic method is described for the quantitative determination of N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-tolindine and α,α,α-trifluoro-2,6-dinitro-N,N-dipropyI-p-toluidine herbicides in formulations. The sample is extracted with benzene, and equal amounts of sample and reference solution in the same concentration range are analyzed by gas chromatography, using an electron capture detector and an SE-30/Diatoport S column. The method has been applied successfully to laboratory-prepared and commercial samples.
Reaction Conditions Necessary for Silylation of Herbicides
Authors: Baur J R , Baker R D , Davis F S
Published: February 2020

The reaction conditions are described for preparation and gas chromatographic analysis of microgram quantities of the trimethylsilyl (TMS) esters of 3,6-dichloro-o-anisic acid (dicamba), (2,4-dichlorophenoxy)acetic acid (2,4-D), (2,4,5-trichlorophenoxy)acetic acid (2,-4.5-T), and 2 water-degradable polymers of 2,4,5-T. Silylation was efficient at 0, 22, and 55°C. A ratio of 1:10 silylating agent (N,O-bis-(trimethylsilyl)acetamide, BSA) to silylation solvent (dimethylformamide, DMF) was optimum for silylation of 2,4-D, 2,4,5-T, and 2,4,5-T polymers. A 1:50 ratio was best for silylation of dicamba. A 1:10 ratio (BSA/DMF) will tolerate up to 1.0 and 0.1% water in the silylation of 2,4-D and 2,4,5-T, respectively. A 1:50 ratio will tolerate up to 0.1% water in the silylation of dicamba. Silylated samples could be analyzed immediately after addition of the silylation reagent. Stability of silylated samples at 22°C was directly proportional to concentration; 1.0 μg samples showed no loss of activity 2.3 hr after reaction. TMS esters were chromatographed on a 6′ × ¼″ glass column containing 3% SE-30 on 80-100 mesh Chromosorb W(HP) at 230°C.
Media to Improve Flagellar Development for Salmonella Flagellar (H) Test
Authors: Poelma P L , Romero A
Published: February 2020

An increasing number of salmonellae, isolated and examined in 1969, failed to give a positive flagellar (H) reaction upon initial testing. After passage through motility medium, the majority of these cultures were positive when retested using the AOAC Salmonella serological flagellar test procedures. Improved detection of flagellar antigens was obtained by using a medium consisting of equal portions of Trypticase Soy and tryptose broths and a small amount of yeast extract. The improvement in the flagellar agglutination test usually occurred without passing the culture through motility medium. The substitution of the improved flagellar broth for tryptophane broth in the AOAC 24 hr Salmonella polyvalent, 41.039, or Spicer-Edwards flagellar, 41.040, tests has been adopted.
Amino Acid Composition of Food Proteins: Inter- and Intralaboratory Variation
Authors: Knipfel J E , Aitken J R , Hill D C , McDonald B E , Owen B D
Published: February 2020

Inter- and intralaboratory variation in amino acid composition of casein, soy flour, and fish flour was examined for 5 cooperating laboratories, utilizing ion exchange chromatographic analyses for amino acids. Duplicate analyses within laboratories exhibited coefficients of variation of 3.7 to 4.4%. Hydrolysis was observed to affect amino acid recoveries to a significant degree, with some amino acids affected to greater extents than others. Laboratories utilizing Moore-Stein type analytical procedures did not appear to be more precise than those using the Piez-Morris method. Adjustment of data to constant total recovery values reduced interlaboratory variation considerably and suggested that recovery constants may be of value in comparing data from different laboratories. Results indicated that different laboratories employing varying analytical procedures may produce practically identical results from a standard sample, although variation may be observed due to characteristics of a specific system. Most variation in results was likely due to sample manipulations rather than to analysis per se.
Collaborative Study of a Modified Method for the Determination of Aflatoxins in Copra, Copra Meal, and Coconut
Authors: Baur F J , Armstrong J C
Published: February 2020

A collaborative study, in which 19 laboratories participated, was conducted on a modified method for the determination of aflatoxins in 2 copra samples, one naturally contaminated, and 4 samples of naturally contaminated copra meal. The sensitivity and precision of the modified method for aflatoxin B1 and total aflatoxins were comparable to the official methods for peanuts and peanut products. Aflatoxins B2, G1, and G2 were reported by most of the laboratories, but background interferences made quantitative measurement less reliable than for B1. The method as it presently stands is also applicable to the analysis of coconut. The method has been adopted as official first action; further study will be directed toward improved precision for analysis of aflatoxins B2, G1, and G2.
Analysis of Radiopharmaceuticals
Authors: Jaffee Max , Ford Leonard
Published: February 2020

Some of the activities of chemists engaged in evaluating and selecting analytical methodology for examination of radiopharmaceuticals and the criteria for assessment of their quality are described. Significant problems, as they relate to a regulatory analysis program, and tentative solutions to these problems are discussed. Conclusions and recommendations, based on the results of analysis of selected radiopharmaceutical preparations of commercial origin, are given.
Collaborative Study of the Analysis of Acetaminophen and Salicylamide in Tablets and Capsules
Authors: Hamilton James L
Published: February 2020

A column chromatographic procedure has been developed for separating acetaminophen and salicylamide in combination with a variety of other drug ingredients in tablets and capsules. Strongly acidic and basic Celite columns are used to trap acetaminophen and salicylamide, respectively. Quantitation is performed using UV spectrophotometry. Identifications are made by the infrared KBr technique on a portion of the column eluates. A collaborative study of the method was conducted. Average recoveries of 99.45% for acetaminophen and 100.9% for salicylamide were obtained for a synthetic standard mixture. The study also included 3 commercial drug products which were assayed for acetaminophen and salicylamide.