bluuebunny/crossref_metadata_2025 huggingface dataset:
Gas-Liquid Chromatographic Method for the Analysis of Carbaryl Insecticide Formulations
Authors: Weyer Lois G
Published: February 2020

A gas-liquid chromatographic method has been developed for the direct analysis of Sevin (carbaryl, 1-naphthyl N-methylcarbamate) technical grade, Sevin 85, Sevin 80, and Sevin 50 formulations. The method consists of dissolving the sample in chloroform containing Thiodan as an internal standard; an aliquot of the supernate is injected into a gas chromatograph with a flame ionization detector and a column packed with 3% SE-30 on 60-80 mesh Gas- Chrom Q. The method compares favorably in accuracy with older methods, is not subject to interferences, is rapid, and has automation possibilities.
Determination of Brominated Vegetable Oils in Soft Drinks by a Combination of Total Bromide Estimation and Gas-Liquid Chromatography
Authors: Conacher Henry B S , Chadha Rajinder K
Published: February 2020

A procedure is presented for the determination of brominated vegetable oils in soft drinks by a combination of total bromide estimation and gas-liquid chromatography (GLC). The method for bromide estimation involves conversion of organic bromide to inorganic bromide by potassium hydroxide fusion, followed by iodometric titration of the inorganic bromide. The bromide content of several common brominated oils ranged from 33.5% (olive) to 43.9% (soybean). Recoveries, based on bromide content, on an orange drink fortified with brominated sesame oil in the range 1–25 mg/10 fluid oz were 94.3–97.5%. Used alone, this technique will not provide accurate brominated oil determination unless the identity of the oil is known. The latter can be deduced from GLC. The analysis of 6 citrus-based soft drinks, using the combined procedures, showed that 5 drinks contained brominated oil in the range 3.1–5.2 mg/10 fluid oz; none was detected in the other drink.
Microbiological Assay of Oleandomycin in Feed: Collaborative Study
Authors: Mayerhofer Hans J , Thompson Sherrill J
Published: February 2020

The present official final action AOAC method of analysis for oleandomycin in feeds, 38.204–38.207, was modified and collaboratively studied. The modifications consist of elimination of the compensating standard curve, changes in the curve point concentrations, and a change in the plating medium. Ten collaborators assayed 4 feed types each at 3 levels of fortification ranging from 1.8 to 18.2 g/ton. All feeds were tested for 2 days, 2 weights per day. The average mean recovery for all feeds at all levels was 92.3% (ranging from 90.11% at the 1.82 g/ton level to 93.51% for the 18.17 g/ton level). The coefficients of variation ranged from 18.2 at the 1.82 g/ton level to 9.3 at the 18.2 g/ton level. The assay variation for all collaborators was 12.5%. No statistically significant differences were found between feed types, levels, and collaborators at the 95% confidence level. This method has been adopted as official first action for the assay of oleandomycin at levels ≤2 g/ton.
Sensitivity Enhancement by Programmed Multiple Development in Thin Layer Chromatography
Authors: Perry John A , Glunz Louis J
Published: February 2020

Programmed multiple development (PMD) is an automatic, cyclic method for a new type of multiple development in thin layer chromatography (TLC). PMD instrumentation allows any number of samples to be developed identically, automatically, and simultaneously. PMD, given equal time of development with respect to conventional TLC development, yields a sensitivity enhancement for major components (in the sample to be detected) of about 10, given also the same sample quantity. The resolution of PMD chroniatograms does not reflect either spot size or overloading up to at least a factor of 20; thus PMD accommodates auxiliary techniques for sensitivity enhancement. The ultimate PMD sensitivity enhancement for traces of substances has yet to be determined.
Collaborative Study of an Automated Method for the Determination of Nitrogen in Meat Products
Authors: Gantenbein Walter M , Schermerhorn Jon L , George Elmer
Published: February 2020

An automated method for nitrogen in meat products was studied collaboratively. Samples were solubilized in sulfuric acid (1 + 1) , cooled to room temperature, and presented to an automated system. Digestion, dilution, and colorimetric measurement of the nitrogen were performed automatically. Samples were also analyzed by the official final action AOAC method, 24.010. Eight collaborators representing 6 laboratories participated in the study. Each participant analyzed 9 different samples in duplicate. Results of the study were satisfactory with an average range of 0.5% protein, average standard deviation of ±0.21%, and average coefficient of variation of 1.20%. The method was found to be as accurate as 24.010 and applicable to meat and meat products containing 0.8–4.0% nitrogen (5.0–25% protein). It has been adopted as official first action.
Study of the Occurrence of Ochratoxin A in Green Coffee Beans
Authors: Levi Colette P , Trenk Hugh L , Mohr Herman K
Published: February 2020

Moldy green coffee beans were found to contain Aspergillus ochraceus and detectable levels of ochratoxin A. The official first action method for the detection of ochratoxins in barley, 26.C15–26.C22, was modified for analysis of coffee beans and a number of survey samples of coffee beans were analyzed. A. ochraceus was found to be present in almost all samples but ochratoxin A was infrequently observed. Ochratoxin A production in sterile green coffee beans inoculated with A. ochraceus under optimal conditions was maximal at 13 days at room temperature but the total amount was low (450 μg/kg). Considerable destruction (approximately 80%) of ochratoxin A occurred during a heat treatment which simulated the roasting of coffee beans.
Pseudomonacidal Activity of Phenolic Disinfectants in Hard Water
Authors: Winicov Murray , Schmidt William , Palochak Muriel
Published: February 2020

Claims for pseudomonacidal activity under use conditions must be validated by hard water performance. Effective phenolic products can be formulated by using o-phenylphenol (OPP) as the principal active ingredient. In tap water containing calcium or magnesium ions, OPP is more effective than any high phenol coefficient phenolic ingredient. Such OPP compositions as are properly formulated with high activity phenolics require a use-dilution concentration providing at least 450 ppm OPP and not less than 750 ppm total phenolics to pass the AOAC use-dilution confirmation test, 4.011, against the 3 principal test organisms in the presence of 400 ppm hard water. Phenolic-based disinfectant products, providing use-dilution OPP concentrations up to 600 ppm and total phenolic concentrations up to 900 ppm, with validated hard water claims are now commercially available. An OPP standard formula is proposed which can be diluted to provide pass/fail usedilutions–a step in the direction of achieving uniformity among different testing laboratories.
Vitamin A in Mixed Feeds, Premixes, and Foods: Collaborative Study
Authors: Parrish Donald B
Published: February 2020

The official final action method for determining vitamin A in mixed feeds, 39.008–39.013, was simplified where possible, principally in extraction and transfer procedures and by omission of chromatography, and was modified to apply to a larger variety of feed and food products. Twenty-two analysts of various degrees of experience participated in the collaborative study of the method, using 6 products. After outliers were eliminated by the Dixon test, data were analyzed and averages were compared with amounts of vitamin A known to be, or estimated, in each sample. The average, per cent deviation from added amount, standard deviation, and coefficient of variation, respectively, on each sample were: breakfast cereal (Sample 1), 23.8 μg/g, 2% less, 3.08, 13% ; mixed feed (or premix), 12.6 μg/g, 5% less, 0.99, 8%; mixed feed containing carotenoid pigments (Sample 3 ), 4.5 μg/g, 3% more, 0.66, 15%; mixed feed without pigments, 4.5 μg/g, 3% more, 0.57, 13% ; liquid feed supplement, 11.4 μg/g, 9% less, 1.44, 12%; powdered breakfast drink, 19.6, 7% less, 1.91, 10%. Some analysts did not correct for pigments in Samples 1 and 3, or for losses on analysis, which could account in part for the degree of variation and for the lower values on some samples. The method has been adopted as official first action to replace 39.008-39.013.
Rapid Screening Method for Simultaneous Determination of Organochlorine and Organophosphate Pesticide Residues in Wheat by Gas-Liquid Chromatography
Authors: Levi Iser , Nowicki Thomas W
Published: February 2020

A previously reported gas chromatographic method for screening of organochlorine residues in wheat has been modified to permit rapid simultaneous screening for common organochlorine and organophosphate residues in wheat. Ground wheat is extracted by ball-milling with ethyl ether-hexane (3+97). The extract is divided into 2 equal portions. One half is used without cleanup for determination of organophosphates by flame photometric detection. The other half is cleaned up on Florisil prior to determination of organoehlorines by electron capture detection. The mean average recovery of 9 organoehlorines from wheat fortified at 0.50 ppm was 80%. Wheat analyzed immediately after treatment with 15 organophosphates showed an average mean recovery of 93%. After 8 weeks' storage, 9 of 15 organophosphates were recovered in excess of 60%, with an average mean recovery of 90% at the 1.00 ppm fortification level. The average mean recovery for 9 organophophates was 7% lower for extraction by ball-milling with ethyl etherhexane than for Soxhlet extraction with methanol- chloroform (10+90).
Collaborative Study of a Method for Organophosphorus Pesticide Residues in Apples and Green Beans
Authors: Laski Ronald R
Published: February 2020

Ten laboratories took part in a collaborative study of a method for organophosphorus pesticide residues in apples and green beans. Six representative organophosphorus pesticides or oxidation products were determined in duplicate at a different level on each crop. The average recovery of the pesticides, using the gas chromatographic potassium chloride thermionic detection system, had the precision and accuracy expected for parathion, paraoxon, carbophenothion oxygen analog, carbophenothion, and EPN. Interference due to reagents made quantitation of dimethoate inaccurate. The average recovery (%) of the pesticides on apples and beans, respectively, was as follows: dimethoate 125.1 and 112.9; paraoxon 99.3 and 103.7; parathion 86.5 and 92.2; carbophenothion oxygen analog 96.7 and 100.1; carbophenothion 88.8 and 102.6; and EPN 90.8 and 98.3. A separate part of the study involved a comparison between the potassium chloride thermionic gasliquid chromatographic detector and the phosphorus- specific flame photometric detector. A statistical analysis of the results obtained from 5 laboratories indicated that the 2 detection systems were equivalent in both precision and accuracy.
Determination of Sorbic Acid in Wine
Authors: Caputi Arthur , Ueda Masao , Trombella Bruno
Published: February 2020

A survey of a number of laboratories engaged in wine analysis showed that 2 basic techniques were used for the determination of sorbic acid. The first utilizes the absorbance by sorbic acid at 260 nm in acidic solution and the second depends on the oxidation of sorbic acid to malonaldehyde which is then reacted with thiobarbituric acid. The resulting red color is measured at 532 nm. A modification of the thiobarbituric method has been adopted by AOAC for the determination of sorbic acid in cheese. We found it could be successfully utilized for sorbic acid analysis in wine with minor changes. It was necessary to separate the sorbic acid from wine by steam distillation prior to either determination. The standard Cash wine volatile acid still is adequate for this purpose and over 9 9% acid could be recovered from a 2 ml wine sample in 200 ml distillate. We studied various parameters in both techniques and arrived at practical procedures for each. Both methods gave acceptable results and we recommend that they be subjected to a collaborative study.
Gas-Liquid Chromatographic Determination of Anethole in Liqueurs
Authors: Parker Robert G
Published: February 2020

In the method described, anethole is extracted from the liqueur sample with chloroform, which eliminates interference from the large amount of sugar present, and is determined by gas-liquid chromatography, using 10% K-20M Carbowax as stationary phase on Chromosorb W (AWDMCS) as solid support. Anethole concentrations were measured in 8 different bottle samples, consisting of 4 different brands produced by 3 different manufacturers. There is a significant difference in the anethole concentration for the 4 brands tested.
Effect of Light on the Extraction of Lead and Cadmium from Glazed Ceramic Surfaces
Authors: Krinitz Benjamin
Published: February 2020

The effect of light on the teachability of cadmium and lead from glazed ceramic surfaces was investigated. Two sets of ceramic plates containing different levels of acid-extractable cadmium when tested by the official AOACASTM method were selected for study. Light had essentially no effect on the extractable lead level; however, the amount of cadmium extracted was dependent on the amount of light present during the leaching process. The amount of cadmium extracted in the presence of light was 1–5 times the amount extracted in the absence of light. The higher the initial cadmium level in darkness, the greater the influence of light. This photosensitive effect is presumed to be due to the presence of unprotected cadmium sulfide pigment in the glaze under test.
A Simple Pressurized Sampling System for Use Prior to Gas Chromatographic Analysis of Aerosol Cosmetics
Authors: Liem Dhiam H , Rundervoort Gerrit J
Published: February 2020

Pressurized sampling of liquids, such as aerosol hairsprays, prior to direct introduction into the gas chromatograph is possible with simple and inexpensive devices, namely, some plastic transfer pieces, a small empty all-glass aerosol container with a valve but without a dip tube, and a special gas syringe (0–25 μl) with a small sliding Teflon valve at the end. This method of sampling has been tested for reproducibility and reliability (coefficients of variation of 1.2% for propellants 11 and 12, 2.3% for ethanol, and 1.1% for dichloromethane). By using the proposed sampling method and a previously reported gas chromatographic method, a quantitative and total analysis of solvents and propellants in aerosol hairsprays can be completed in 1 hr. Fifty commercial aerosol hairsprays have been analyzed by using this system.
Cylinder Plate Assay for Lasalocid Sodium
Authors: Scheiner Jacob M , Cort Winifred M , Chen Jessica
Published: February 2020

A microbiological assay method is described for the determination of the coccidiostat lasalocid sodium in premixes and finished poultry feeds. Premixes are extracted with absolute methanol and diluted to assay range with 25% methanol in the final dilution. Feed samples are extracted with ethyl acetate and an aliquot is evaporated at 60°C. The residue is dissolved in hexane, the antibiotic is extracted with 75% methanol in water, and the extract is diluted to the assay range with a final methanol concentration of 25%. Microbiological activity by horizontal agar diffusion is measured by the cylinder plate technique with Bacillus subtilis ATCC 6633. Recoveries of drug from premix are quantitative. A correction is made for recovery from feeds which, in this laboratory, has averaged 82% for mash feeds and 75% for pellets at a level of 0.0075% lasalocid sodium. Bacitracin, lincomycin, 3-nitro-4-hydroxyphenylarsonic acid, ipronidazole, and a combination of sulf adimethoxine and ormetoprim at current use levels in feeds do not interfere.
Spectrophotometric Determination of Carbadox in Swine Feeds
Authors: Goras John T , Gonci Donald A , Murai Kotaro , Curley James E , Gordon Philip N
Published: February 2020

The assay method is applicable to samples containing 0.00110-0.0606% carbadox (methyl 3-(2-quinoxalinylmethylene)carbazate - N1, N4-dioxide) (10–550 g/ton). Carbadox is leached from the sample with chloroform-methanol (3+1), followed by a series of solvent-solvent extractions, column chromatography, and finally the spectrophotometric measurement of the carbadox content of the final solution at 420 nm. This treatment of the feed or feed supplement sample serves to isolate the carbadox from materials that might interfere in the spectrophotometric measurement. The method of standard addition compensates for a feed or feed supplement matrix effect in the assay. A water pretreatment step improves recovery of drug from pelleted feeds. Assay results for feeds and feed supplements that were prepared under carefully controlled conditions showed good agreement between the amounts of carbadox added and found. Multiple assay values for feeds containing 0.00551% carbadox exhibited a coefficient of variation of about 5%. Assay results for commercial feed and feed supplement samples indicated that the assay method is applicable to a wide variety of feeds and feed supplements.
Improved Gas-Liquid Chromatographic Method for Determining Ethylenethiourea in Plants
Authors: Nash Ralph G
Published: February 2020

In the improved method for determining ethylenethiourea (ETU) in plants, pentafluorobenzoyl chloride was substituted for trifluoroacetic anhydride derivatization of S-benzylated ETU. The resulting product (2-(benzylthio)-l- (pentafluorobenzoyl)-2-imidazoline) gave recoveries of near 100% and improved the electron capture gas-liquid chromatographic (GLC) response. The product can be cleaned up by column chromatography to eliminate interfering GLC peaks. Soybeans grown in soil treated with 14C-ETU resulted in a high concentration of 14C residues in leaves, but only traces of ETU were detected by either 14C or GLC measurements.
New, Improved Thin Layer Chromatography for Poly chlorinated Biphenyls, Toxaphene, and Chlordane Components
Authors: Ismail Raja J , Bonner Frances L
Published: February 2020

Reverse phase partition thin layer chromatography is described for the separation of the different components in polychlorinated biphenyl compounds, chlordane, and toxaphene. Plates prepared from washed aluminum oxide, with silver nitrate incorporated into the layer, are saturated with a nonpolar solvent (immobile phase), air-dried overnight, and spotted. A mixture of polar solvents is used as the mobile phase. After exposure to longwave ultraviolet light, dark blue silver chloride spots form on a white background. As little as 1 μg Aroclor can be detected by this method, which can be applied for qualitative and semiquantitative measurements. Distinct patterns are obtained for Aroclor reference materials which are resolved from most DDT analogs and other commonly occurring chlorinated pesticides. Since the use of infrared, ultraviolet, nuclear magnetic resonance, and mass spectroscopy as supplementary methods for qualitative analysis involves a large capital outlay which is often beyond the resources of small laboratories, the technique is most valuable to the chemist in such laboratories where time and money are important factors.
Gas-Liquid Chromatographic Determination of Vitamin D2 in Multiple Vitamin Tablets Containing Minerals and Vitamin E Acetate
Authors: Edlund David O , Filippini Florido A , Datson James K
Published: February 2020

A gas-liquid chromatographic procedure used to determine vitamin D2 in multiple vitamin tablets has been modified to make it applicable for analysis of multiple vitamin tablets containing minerals and vitamin E acetate. The procedure modifications involve pre-extraction with ether, solution in an alcoholic sulfuric acid-pyridine mixture, and column chromatographic separation on phosphate-treated alumina. The modified procedure has been statistically evaluated. A 2.2% coefficient of variation and 100.3% average recovery were obtained for the samples evaluated.
Collaborative Study Comparing Two Methods for the Determination of Aflatoxins in Pistachio Nuts
Authors: DiProssimo Vincent
Published: February 2020

Two official first action methods for the determination of aflatoxins in peanuts and peanut products, method I (26.015-26.020) and method III (26.026-26.030), were modified slightly for the analysis of pistachio nuts. Thirteen collaborators analyzed naturally contaminated in-shell pistachio nuts, aflatoxin-free pistachio nuts, and pistachio nut composites spiked with known amounts of aflatoxins. The extraction and cleanup in method III are relatively simple and require no chromatography, whereas the lengthier method I employs column chromatography, producing a cleaner thin layer chromatographic extract. On the basis of the collaborative results obtained, both methods have been adopted as official first action for the determination of aflatoxins in in-shell pistachio nuts.
Rabbit Skin Test for Estimation of T-2 Toxin and Other Skin-Irritating Toxins in Contaminated Corn
Authors: Chung Choong W , Trucksess Mary W , Giles Albert L , Friedman Leonard
Published: February 2020

A rabbit bioassay test has been developed which can be used for screening large numbers of field samples of corn for T-2 and other toxins. Two μl each of the control solutions, 0.005–0.12 μg standards, and about 12 samples in ethyl acetate were applied simultaneously to the closely clipped skin of a 2–3 kg young rabbit. The skin reactions were read at 24, 48, and 72 hr. The prominent features of the reactions were erythema, edema, and necrosis. The T-2 toxin equivalences of the samples were estimated by the degree of the skin reactions caused by the standards. The method is reliable to at least 0.01 μg/test or 50 ppb. Graded response to the toxin is dependent upon the use of sensitive animals and properly diluted samples and standards. Rabbits were more sensitive than weanling rats or young guinea pigs, and the method showed better reproducibility with rabbits. Citrinin and zearalenone (F-2) showed negative skin reactions when applied at a level of 20 μg/skin site. They also showed poor skin reactions when administered by intradermal injection into rabbit skin. However, all 3 mycotoxins showed distinct skin reactions in guinea pigs by the intradermal route. The test was as sensitive as the topical test using rabbits with T-2 toxin. The prominent feature of the skin reaction was induration.
Colorimetric Estimation of Novatropine in Pharmaceutical Preparations
Authors: Karawya Mohamed S , Ghourab Mohamed Galal , Mohamed Ibtisam H
Published: February 2020

Novatropine (homatropine methylbromide) is estimated colorimetrically on the basis of the formation of a colored complex with bromothymol blue. As much as 100 μg novatropine/ml can be estimated in various pharmaceutical preparations without interference from other ingredients.
Determination of Docosenoic Acids in Fats and Oils by Gas-Liquid Chromatography
Authors: Conacher Henry B S , Chadha Rajinder K
Published: February 2020

A rapid gas-liquid chromatographic (GLC) procedure has been developed for the determination of docosenoic acids in fats and oils. The method involves conversion of a known weight of oil to methyl esters using sodium methoxide-methanol, with a known weight of methyl tetracosanoate used as an internal standard. After acidification and extraction into hexane, esters are analyzed by GLC on a diethylene glycol succinate column. The percentage of docosenoic acids is calculated from the docosenoate and internal standard peak areas. The method is particularly suited to the determination of low levels (<5%) of docosenoic acids.
Method for Testing the Purity of Israeli Citrus Juices
Authors: Lifshitz Abraham , Stepak Yedael , Brown Morton B
Published: February 2020

An extensive study of Israeli orange and grapefruit juices has been carried out in the last 7 years (1966-1973). About 1000 samples of natural citrus juices were examined for a large number of analytical parameters. On the basis of statistical evaluation of the data of the first year and consideration of their ease of performance, 5 analytical parameters were selected: Brix, formol number, chloramine T number, total sugars, and chlorides. A multivariate normal test was performed under which adulteration or dilution of 15% or more is very likely to be detected at a 1 % level of significance. Analytical results obtained each subsequent year were integrated into multiyear results. Pasteurization of the juice and storage for 6 months did not affect the power of the method.
Sample Preparation for Nutrient Analysis
Authors: Aulik David J
Published: February 2020

Difficulties encountered in the preparation of samples for nutrient analysis are discussed, in regard to both sample type and nutrient to be analyzed. Problems and potential solutions are outlined for obtaining labeling information for proximate or compositional analyses, vitamin content, and minerals. Problems peculiar to specific items are also described.
Modification of the Gutzeit Arsine Generation Method for Improved Recoveries of Arsenic
Authors: Ishida Kohzoh , Braun Heinz E
Published: February 2020

A minor modification in the arsine generation method is described which permits improved recoveries (average of 9%) of arsenic in fortified and field-treated soil samples. The modification involves the controlled addition of hydrochloric acid to permit a less vigorous reaction with the zinc and the formation of arsine gas at a slower rate.
Rapid Method of Screening Forage Breeding Material, Using a Fibrometer
Authors: Arora Surendra K , Das Bhagwan
Published: February 2020

A simple device, a fibrometer, has been devised for measuring the bulk value of a forage sample. The bulk value obtained by using the fibrometer was significantly and negatively correlated with acid-detergent fiber and cellulose. It was also significantly and positively correlated with in vivo and in vitro dry matter digestibility. This method reduces the effort required to analyze a large number of breeding materials for nutritional value and is also economical.
Confirmation of Chlorinated Paraffins by Dechlorination
Authors: Zitko Vladimir
Published: February 2020

Confirmation of chlorinated paraffins (C20舓C28) by dechlorination with sodium bis(2-methoxyethoxy) aluminum hydride is described. The minimum amount of chlorinated paraffins required for the test is 10 μg. Chlorinated paraffins containing up to 50% chlorine yield paraffins, unsaturated hydrocarbons, and hydroxy compounds. Maximum yield of straight chain C20舓C28 paraffins is obtained after 2 hr at 150°C. Chlorinated paraffins containing 70% chlorine yield unsaturated hydroxy compounds with fluorescence excitation and emission maxima at 320舓340 and 420舓450 nm, respectively. The presence of chlorinated paraffins in an antifouling paint was confirmed by the described procedure. The technique can also be used to analyze lipid-containing extracts of biological samples.
Determination of Selenium in Animal Feed Premix by Atomic Absorption Spectroscopy
Authors: Ng Samuel , Munroe Maurice , McSharry William
Published: February 2020

An atomic absorption spectrophotometry method for the determination of selenium in animal feed premixes is described. The method involves digesting the samples by heating with perchloric acid and hydrogen peroxide. No pre-concentration or separation is required other than filtering the insoluble material remaining after digestion. Concentrations from 0.0057 to 0.42% selenium were measured. The relative standard deviation over this range averaged 4.6%. A matrix effect, which could be overcome by either preparing the standards with a matrix or using the standard addition technique, was noted at ≤0.02% selenium. The results obtained by each method and by x-ray fluorescence are shown and compared with the claimed selenium content. When the matrix effect is overcome, results by atomic absorption spectroscopy and x-ray fluorescence agree within 15% or better at all levels.
Simple and Fast Fluorometric Method for the Determination of Glycine (Or Any Primary Amine) in Dietetic Beverages
Authors: Coppola Elia D , Hanna J Gordon
Published: February 2020

The reagent fluorescamine (4-phenylspiro- (furan-2 (3H),l´-phthalan)-3,3´-dione), which reacts selectively with primary amines in alkaline solution, has been used to determine glycine in dietetic beverages in a simple and fast fluorometric procedure. As little as 0.02% glycine can be determined. An average recovery of 100.3±3.76% was obtained for added glycine in a series of 9 determinations. The method can be used as a screening procedure to confirm or exclude the presence of glycine in dietetic beverages.
Conductivity Detector for Nitrogen Compounds: Maintenance Program Enabling Gas-Liquid Chromatographic Analysis of Trace Residues in Crude Soil Extracts
Authors: Sarna Leonard P , Webster G R Barrie
Published: February 2020

A maintenance program for the Coulson conductivity detector is described which incorporates a new rapid method of decontaminating the stainless steel transfer lines and the vent valve of the detector system. Regular use of these maintenance procedures facilitites use of the Coulson conductivity detector for the analysis of trace residues of nitrogen-containing herbicides in crude soil extracts by maintaining detector sensitivity over an extended period of time and ensuring reliable performance from the instrument. Thus it is possible to avoid lengthy cleanup of analytical samples and the losses of material which might be involved, and to make maximum use of selective response of the Coulson conductivity detector. Approximately 2 days' down time is required every 3 months for this procedure.
Direct Determination of N'-Phenyl Urea Derivatives in Herbicide Technical Products and Formulations, Using Gas-Liquid Chromatography
Authors: Buser Hansueli , Grolimund Karl
Published: February 2020

The direct gas-liquid chromatography of a number of N'-phenyl-.N,N-dimethylureas and N'- phenyl-N-methoxy-N-methylureas has been investigated. Representatives of both groups have been studied in detail, calibration curves using an internal standard have been established, and herbicide technical products as well as formulations have been analyzed quantitatively. A 2 or 3% silicone SE-30 column was used in conjunction with a flame ionization detector. Operating temperatures were chosen on the basis of thermal stability data obtained by differential scanning calorimetry. Gas-liquid chromatography- mass spectroscopy coupling has confirmed that intact urea compounds elute from the chromatographic column.
Pro-Milk Method for the Determination of Protein in Milk by Dye Binding
Authors: Sherbon John W
Published: February 2020

The Pro-Milk method was compared to the official final action Udy method, 16.037-16.040, for 166 samples of raw milks from individual cows and to the official final action Kjeldahl method, 16.035, for 54 similar samples. Averages ± standard deviations of the differences were 0.019±0.017 and 0.027±0.109% protein for the 2 methods, respectively. Fat test or protein level of the samples did not affect the magnitude of the difference between the Pro-Milk and either of the other 2 methods. The Pro- Milk comparisons have also been made on samples of processed milks with similar results. A number of comparisons of the Pro-Milk method to other methods for protein in milk have been reported in the literature. The principles of the Pro-Milk method differ from the Udy method only in the type of dye used. Periodic calibration and routine control of the Pro-Milk method is required because of variability in assay of the Amido Black 10B dye.
Quantitative Determination of L-Ascorbic Acid by Gas-Liquid Chromatography
Authors: Schlack Janis E
Published: February 2020

A gas-liquid chromatographic method for L-ascorbic acid in foods and food products has been devised. Ascorbic acid is extracted into an ethanol solution, precipitated with lead acetate, regenerated from the lead salt as its trimethylsilyl derivative, and chromatographed on an SE- 30 column. Recoveries averaged 100.1%; the standard deviation was ±0.23%.
Isolation of Volatile N-Nitrosamines in Edible Vegetable Oils and Cooked Bacon Fat
Authors: White Richard H , Havery Donald C , Roseboro Emma L , Fazio Thomas
Published: February 2020

Volatile N-nitrosamines can be isolated from cooked bacon fat by the following procedures: The sample is distilled from alkaline solution and the nitrosamines are extracted with methylene chloride and cleaned up on a silica gel column (procedure A). The same procedures, preceded by an extraction with methylene chloride- sodium hydroxide, are used for isolation of N-nitrosamines from soybean oil samples (procedure B). Gas-liquid chromatography with the thermionic detector was used for the determinative step. Recoveries of 14 N-nitrosamines added to 25 g soybean oil samples at 10 and 20 ppb ranged from 67 to 100% for procedure B; these recoveries were 5舓10% higher than those from procedure A. No nitrosamines were detected in 4 commercial samples of soybean oil; however, they were found in cooked bacon fat at levels ranging from 45 to 207 ppb (μg/kg).
Preparative Method for Gas Chromatographic/Mass Spectral Analysis of Trace Quantities of Pesticides in Fish Tissue
Authors: Veith Gilman D , Kuehl Douglas W , Rosenthal Jeffry
Published: February 2020

A large capacity, low efficiency pesticide cleanup method is combined with a small capacity, high efficiency method for gas chroma tographic/mass spectral analysis of fish tissue. Trace chemicals are extracted from the tissue, removed from the bulk of the co-extracted lipids through selective desorption from Micro Cel-E, and isolated from the remaining lipids by gel permeation chromatography. The procedure is capable of cleaning up the extract from several hundred grams of fish, minimizes sample contamination, and permits identification of xenobiotic chemicals present at ng/g concentrations.
Rapid Screening Method for Aflatoxins and Zearalenone in Corn
Authors: Thomas Fred , Eppley Robert M , Trucksess Mary W
Published: February 2020

The methanol-water extraction system used in AOAC Method II for aflatoxins extracts both the aflatoxins and zearalenone from corn. Using this methanol-water extraction system as a base, a rapid screening procedure has been developed for these mycotoxins. The methanol-water extract is defatted with hexane and the pigments are precipitated with copper carbonate. The aflatoxins and zearalenone are subsequently extracted into chloroform and are then detected by half-plate TLC. An elapsed time of about 1 hr is required to analyze 1 sample. The sensitivity of the method is about 2 μg/kg for aflatoxin B1 and 100 μg/kg for zearalenone.
Gas-Liquid Chromatographic Determination of Coumarin (1,2-Benzopyrone) in May Wine
Authors: Dyer Randolph H , Martin Glenn E , Butts Boyd B
Published: February 2020

A method for the determination of coumarin (1,2-benzopyrone) in wine is described. The method calls for the gas chromatographic comparison of chloroform extracts of 2 aliquots of the sample, 1 aliquot having been spiked with a known amount of coumarin. The results of a series of prepared samples containing from 2.5 to 10.0 mg coumarin/L are given and these show an average of 3.7 relative per cent error. The results of the analysis of 10 May wines are also given. The method is fast, and accurate results are obtained. It is suggested that an Associate Referee be appointed and that the coumarin method be collaboratively studied.
Collaborative Study of a Joint AOAC-OICC (Office International du Cacao et du Chocolat) Method for the Determination of Alkalinity of Ash in Cacao Products
Authors: Rostagno Walter
Published: February 2020

In order to develop a uniform method for the determination of alkalinity of soluble and insoluble ash, AOAC methods 13.005 and 13.006 and OICC method 4b/1952 were compared. Five samples were sent to 10 collaborators: A, high ash cocoa; B, low ash cocoa; C, breakfast chocolate containing 30% A and 70% sugar; D, plain chocolate containing 25% B, 45% sugar, and 30% cocoa butter; and E, milk chocolate containing 10% B, 28% milk solids, 40% sugar, and 22% cocoa butter. The following within-laboratory and between-laboratory standard deviations were obtained from analysis of the collaborative data for alkalinity in soluble ash: OICC—Samples A and B, 1.5116 and 3.4337; Samples C–E, 0.7285 and 1.0394; AOAC—Samples A and B, 1.2800 and 3.6996; Samples C–E, 0.2956 and 0.8001. Corresponding values for alkalinity in insoluble ash were: OICC—2.1753 and 3.6856, 0.5100 and 1.0029; AOAC—1.5652 and 5.5006, 0.3129 and 1.6501. On the basis of these results, a joint AOACOICC method, based on the determination of alkalinity in soluble ash by the AOAC method and the determination of alkalinity in insoluble ash by the OICC method, has been adopted as official first action.
Detection of Ochratoxin A in Barley, Using Silica Gel Minicolumns
Authors: Hald Benedicte , Krogh Palle
Published: February 2020

A simplified procedure has been developed to detect ochratoxin A in cereals which can be used in the field where equipment for thin layer chromatography is not available. The procedure includes extraction of the acidified sample with chloroform, purification over sodium bicarbonate, and minicolumn chromatography. Under longwave ultraviolet light ochratoxin A appears as a blue-green fluorescent band at the lower end of the column. Contamination levels as low as 12 ppb can be detected by this method.
Automated Fluorometric Determination of Thiabendazole
Authors: Ott Daniel E
Published: February 2020

An automated fluorometric method is presented for the determination of thiabendazole (2-(4’-thiazolyl)benzimidazoIe) in 0.1/V HC1 solutions. Test solutions of at least 1.1 ml starting volume are sampled and pumped successively at the rate of 60/hr into a fluorometer equipped with a simple flowcell. The minimum level of detection of the fungicide is about 0.05 μg/ml.
Collaborative Study of a Method for the Analysis of Dry Methoxychlor Formulations
Authors: Pease Harlan L
Published: February 2020

A collaborative study has been completed on a method for determining methoxychlor content in dry formulations. The method is based on a total halogen determination plus a selective, qualitative thin layer chromatographic (TLC) measurement to establish that p,p’-methoxychlor is the primary halogen-containing organic species present in the formulation. After extraction of the sample with toluene, the toluene solution of methoxychlor is treated with sodium biphenyl to convert all halogen to the halide. The halide is then extracted with a solution of nitric acid and titrated with silver nitrate according to the Volhard procedure or potentiometrically, using a pH meter assembly. Based on the results obtained from 7 collaborators, the standard deviation of the method is about 0.48% at the 50% level. The qualitative TLC measurement is made on an aliquot of the initial toluene extract, using a selective halogen detection system. The method has been adopted as official first action.
High-Pressure Liquid Chromatographic Determination of Uncombined Intermediates and Subsidiary Colors in FD&C Blue No. 2
Authors: Singh Manjeet
Published: February 2020

A high-pressure liquid chromatographic method is presented for the isolation and determination of uncombined intermediates and subsidiary colors in FD&C Blue No. 2 (indigotine, C.I. No. 73015). Samples of FD&C Blue No. 2 containing 0.1–0.3% isatin, 0.1–0.3% isatin 5-sulfonic acid, 0.1–5.0% monosulfonated indigo, and 1.0–18.0% 5,7’-disulfonated indigo were prepared and analyzed by using this method. Recoveries ranged between 92 and 102%.
Fast, Short-Column Separation and Fluoromeitric Determination of Monosodium Glutamate in Foods
Authors: Coppola Elia D , Christie Spence N , Coppola J Gordon
Published: February 2020

In a simple and fast procedure, monosodium glutamate in food products is first separated by a short ion exchange column and subsequently determined fluorometrically with fluorescamine. An average recovery of 90.8% with a standard deviation of ±6.67% was obtained for added monosodium glutamate in a series of 8 products. As little as 0.05% monosodium glutamate can be determined. The method is faster than the official method and saves 5 hr/ determination.
Isolation and Characterization of the Photoalteration Products of cis- and trans-Chlordane
Authors: Onuska Francis I , Comba Michael E
Published: February 2020

Ultraviolet irradiation of cis- and trares-chlordane yielded 3 photolysis products. The expected half-caged analog of cis-chlordane was formed in high yield, and 2 minor photoproducts of trans-chlordane were observed. One of these products was a half-caged isomer. The individual photoproducts were isolated by thin layer chromatography and characterized by infrared, nuclear magnetic resonance, and mass spectrometry.
Collaborative Study of a Semiautomated Colorimetric Analysis of Digoxin Tablets
Authors: Juhl William E
Published: February 2020

A semiautomated thiobarbituric acid colorimetric analysis for digoxin was collaboratively studied by 6 laboratories. Collaborators were supplied with 3 composites of tablets of different dosage levels. Results agreed with the USP method. The coefficients of variation ranged from 0.46 to 2.73%. The method has been adopted as official first action.
Determination of Procaine and Related Local Anesthetics. I. Partition Chromatographic Separation and Assay of Mixtures of Procaine with Tetracaine and with Propoxycaine
Authors: Doyle Thomas D , Proctor Joseph B
Published: February 2020

Determination of ionization and extraction constants for procaine, tetracaine, and propoxycaine led to selection of a simple partition chromatographic system for separation and assay of mixtures of these anesthetics. A 65% solution of chloroform in isooctane elutes tetracaine or propoxycaine from a pH 4:sodium bromide column; procaine is retained and subsequently eluted by chloroform as the bromide ion-pair. The anesthetics are then determined spectrophotometrically. Results of assay of standard and commercial formulations are presented.
Agar Well Technique for Antibiotics in Animal Feeds
Authors: Thorpe Virginia A
Published: February 2020

The agar well technique compares favorably with the cylinder plate assay in accuracy, sensitivity, and precision. It is more flexible and more rugged, and growth of seed organism is not inhibited. The wells are precision cut with Grafar gel punch assembly with sets (6) of 10, 7, 5, 4, and 3 mm cutters. The wells are easily and rapidly filled with short, disposable Pasteur pipets fitted with rubber bulbs. The smaller wells are filled with capillary pipets. The diameter of the well (independent of volume) appears to be a function of concentration. For every decrease in the diameter size of the well, concentration can be increased, at least to the next higher level of the standard response line. Extracts of chlortetracycline containing as much as 3.2 μg/ml can be analyzed if the 3 mm wells are used and with no sacrifice in accuracy or precision. This works especially well for antibiotic premixes. The technique has been used successfully for penicillin, streptomycin, chlortetracycline, oxytetracycline, oleandomycin, and tylosin.
Collaborative Study of the Determination of Boric Acid in Caviar by Emission Spectroscopy
Authors: Franco Vincent , Holak Walter
Published: February 2020

Caviar samples were spiked at the 0.1 and 0.2% levels and digested with nitric acid in a closed Teflon-lined digestion vessel to prevent volatility losses. The boron was complexed with 2-ethyl-l,3-hexanediol and extracted into methyl isobutyl ketone. The emission of the boron oxide band was measured in a nitrous oxidehydrogen flame. The mean recoveries at the 0.1 and 0.2% levels for 6 collaborators were 95.7 and 97.1%, respectively. The method has been adopted as official first action.
o-Toluenesulfonamide in Saccharin Preparations
Authors: Stavric Bozidar , Klassen Ray
Published: February 2020

Twenty saccharin-containing table sweeteners, in the form of tablets, liquids, crystals, or blends, and manufactured or distributed by 15 different companies, were analyzed for their o-toluenesulfonamide (o-TS) content. A previously described procedure for the determination of o-TS in commercial saccharin was found to be applicable to the determination of o-TS in these preparations. o-TS was found in all analyzed samples, in amounts ranging from 57 to 3811 ppm. In some cases the concentration of o-TS varied even from lot to lot from the same manufacturer. One pair of lots contained 57 and 67 ppm o-TS, respectively, while in another 711 and 3003 ppm o-TS were found. Gas-liquid chromatographic patterns of samples from the same distributor (or manufacturer) were similar and characteristic of the brand. Recoveries of o-TS from liquid and tablet preparations were almost quantitative, while recoveries from saccharin blends were in the 95–103% range.
Atomic Absorption Spectrophotometry: Determination of Chromium in Plants
Authors: Cary Earle E , Olson Oscar E
Published: February 2020

A previously reported method for the determination of chromium in plants and biological materials has been simplified. The method, which involves wet digestion, isolation and concentration of chromium by liquid-liquid extraction, and final determination by atomic absorption spectrophotometry, is sensitive to about 20 ng chromium. Recovery studies and analysis of standard materials show that this method is reliable.
Collaborative Study of a Method for the Isolation of Light Filth from Breading of Frozen Food Products
Authors: Kvenberg John E
Published: February 2020

A method has been developed for the isolation of light filth from food breadings. The method involves a detergent boil, wet sieving, and flotation in an acid-alcohol, mineral oil flotation system in a Corning percolator. Collaborative studies resulted in clean filter papers and acceptable recoveries of added rodent hairs and insect fragments. The method has been adopted as official first action.
Sensitive Trapping and Gas Chromatographic Method for Vinyl Chloride in Air Samples
Authors: Ives N Fred
Published: February 2020

A simple and sensitive method is described for determining vinyl chloride monomer in air. Vinyl chloride monomer from a sample of air is trapped onto a Tenax GC trap cooled with Dry Ice. The trap is installed on a gas chromatograph by a simple valve arrangement. The trap is heated, and the entire sample is flushed onto the gas chromatographic column. Vinyl chloride is determined at 6 and 60 ppb (v/v) levels with recoveries ranging from 79 to 104%.
Reduction of Aflatoxins B1 and B2 with Sodium Borohydride
Authors: Asho Samy H , Chu Fun Sun
Published: February 2020

Reduction of aflatoxin B1 and a flat ox in B2 with sodium borohydride quantitatively yielded new fluorescent derivatives, designated as aflatoxin RB1 and aflatoxin RB2. Mass spectronietric data showed that RB1 and RB2 were trihydroxy derivatives of B1 and B2, respectively. Nuclear magnetic resonance analysis revealed that new chemical shifts were present in aflatoxins RB1 and RB2 in addition to those of the parent aflatoxins. The new compounds had lower melting points and different ultraviolet and infrared spectra compared to aflatoxins B1 and B2 and the monohydroxy derivative aflatoxicol. They were less toxic to chick embryos than the parent toxins. Since the reduction yields were quantitative and since the reduction products could be detected at low levels comparable to those for B1 and B2, the reduction reaction could be used as a confirmatory test for both aflatoxins B1 and B2. Preliminary results obtained from gas-liquid chromatography (GLC) analysis of the trimethylsilyl derivatives of aflatoxins RB1 and RB2 indicated that these compounds could furnish the basis for developing an analytical GLC method for aflatoxins B1 and B2.