bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automated Enzymatic Determination of L-Lysine in Grain
Authors: Wall Larry L , Gehrke Charles W 
Published: February 2020

Abstract
An accurate and precise automated method has been developed for the determination of lysine in grain hydrolysates. The enzyme L-lysine decarboxylase specifically catalyzes removal of the carboxyl group from L-lysine, producing an amine and carbon dioxide. This reaction has been automated. The carbon dioxide produced was selectively dialyzed into a stream of carbonate with phenolphthalein by a dialysis block containing a carbon dioxide gas dialysis membrane. Ground samples of grain (250 mg) were hydrolyzed 20 hr in 25 ml 6N HC1 at 110°C Aliquots were evaporated to dryness under nitrogen with low heat. The samples were redissolved in carbon dioxide-free water and the enzyme was suspended in pH 6.5 phosphate buffer. Analyses were made at 30/hr with a sample-to-wash ratio of 4:1. A standard curve with a range of 0 to 90 ppm lysine was expanded to full scale on the recorder. From the comparative height of each sample peak vs. the standard curve, the per cent lysine in the original sample can be calculated. Repeated analyses on 15 samples, 5 each of corn, mungbeans, and soybeans, by the automated method showed that the precision was good, and the results were in good agreement with classical ion exchange data. The automated method for lysine in corn has been used in our laboratory to analyze 1500–2000 corn samples each year for the last 5 years.
Identification of 2-, 3-, and 4-Methoxyamphetamines and 2-, 3-, and 4-Methylamphetamines
Authors: Bailey Keith , Beckstead Harry D , Legault Donald , Verner Denise 
Published: February 2020

Abstract
The identity of samples of 2-, 3-, and 4-methoxyamphetamine and 2-, 3-, and 4-methylamphetamine is conclusively established by comparison of their spectra. Ultraviolet, proton magnetic resonance, and mass spectra distinguish and identify the 2 series and infrared spectra differentiate isomers; reference spectra and data are provided. Thin layer and gas-liquid chromatographic systems suitable for distinguishing these compounds are described.
Improved Method for Fat and Oil Analysis by a New Process of Extraction
Authors: Randall Edward L 
Published: February 2020

Abstract
Equipment and procedures have been designed for the rapid (30 ruin) and accurate extraction of fats, waxes, and oils from plant and animal tissues. A 2–5 g sample is ovendried, immersed in hot ethyl ether 10 min, raised out of the solvent, and further extracted and rinsed with solvent condensate for 20 min. The ethyl ether is removed by evaporation and the residue is weighed. Excellent replication of results and agreement with analysts using Goldfisch and Soxhlet extractors were obtained. Sr (intralaboratory) values on feed samples ranged from 0.01 to 0.06%. Sb (interlaboratory) values for the same samples ranged from 0.03 to 0.15%. The same values for meat samples, which are less homogeneous, ranged from 0.18 to 0.72%.
The Statistics of Nutrition Sampling and Analysis
Authors: Roberts Howard R 
Published: February 2020

Abstract
It is widely recognized that there is natural variation in the nutrient content of food products. When one attempts to measure nutrient levels, another source of variation becomes apparent—that inherent in the measurement process itself. Analytical variation is, of course, apparent when different methods are used but can also occur with the same method because of differences among laboratories and/or analysts. Both in its own right and more especially with regard to evaluating compliance with labeling regulations, method variability is of critical importance. In order to appreciate the role of analytical methodology, the nutrition labeling regulations and the procedures by which the Food and Drug Administration will assess compliance must first be thoroughly understood. This paper is directed toward that understanding.
Interlaboratory Variability in Nutrient Analyses: Two Cooperative Studies
Authors: Elkins Edgar R 
Published: February 2020

Abstract
Canned tomato juice and canned peas were analyzed for those nutrients that are mandatory as required by the nutrition labeling regulations. Twenty-four laboratories participated in the studies, using AOAC methods predominately. Results seem to indicate that, with the exception of the fat determination, methods for proximate analyses are satisfactory. Interlaboratory variability as measured by the coefficient of variation was quite large for the fat determination, 60% in tomato juice and 80% in peas. However, at the level present in both products, per cent fat is not significant from a nutrition labeling point of view. Rather significant levels of variability are apparent for most of the vitamin and mineral determinations which would indicate that methods need to be refined and that studies such as this need to be continued for these methods in other products that will be labeled nutritionally.
Applications of Nuclear Magnetic Resonance Spectroscopy to Antibiotics. I. Specific Identification of Penicillins and Cephalosporins
Authors: Wilson William L , Avdovich Hajro W , Hughes David W 
Published: February 2020

Abstract
The nuclear magnetic resonance spectra of various commercially available penicillins and cephalosporins are given. General spectral features, as well as specific resonances, are discussed and their application in the identification of these antibiotics is outlined.
Comparison of Wet Ashing and Dry Ashing for the Determination of Arsenic in Marine Organisms, Using Methylated Arsenicals for Standards
Authors: Uthe John F , Freeman Harry C , Johnston John R , Michalik Paula 
Published: February 2020

Abstract
A vanadium catalyzed pentoxide-sulfuric acid-nitric acid digestion procedure is described which gave higher values for total arsenic than the AOAC dry ash procedure with fish and shellfish tissue. Recoveries of added methylarsenic compounds were also lower by dry ashing procedures but essentially complete by the new ashing procedure. Arsenic levels in a variety of shellfish and fish tissues as determined by wet ashing averaged 6.3% higher than dry ash values. In lobster hepatopancreas the difference was 13.1% for a large number of samples from a number of sampling areas.
Tobacco Analysis: Sequential Differential Solvent Extractions
Authors: Steele John A 
Published: February 2020

Abstract
A method is described for sequential differential solvent extraction of tobacco, using petroleum ether (38-58°C), tetrahydrofuran, acetonitrile, 95% ethanol, 20% water-dioxane, and water. The method is suitable for the monitoring of tobacco fermentation, the differentiation between cigarette and cigar filler tobaccos, and the assaying of the tobacco content of cigar wrapper material or manufactured reconstituted tobacco sheets.
Proposed Standard Methods for Ink Identification
Authors: Kelly Jerry D , Cantu Antonio A 
Published: February 2020

Abstract
Two methods are presented for the identification of ink, both of which are currently being used by laboratories involved in ink analysis. Both methods incorporate physical and chemical procedures. The differences are primarily in chemical methods involving spot tests and thin layer chromatographic (TLC) techniques. Furthermore, one method utilizes spectrophotometric scanning of the TLC plate whereas the other method utilizes solution spectrophotometry. It is recommended that both methods be evaluated by several laboratories.
Development of Latent Fingerprints on a Nonporous Surface, Using Standard Brushing Method for Powders: Second Collaborative Study
Authors: Connor Charles M 
Published: February 2020

Abstract
Twelve latent fingerprint examiners participated in a collaborative study of a modification of the official first action powder brushing method for the development of latent fingerprints. Latent images were placed on glass slides by the examiners, using male and female subjects. The standard brushing method, using black, copper, and gray powders provided by the Associate Referee, was used to develop the fingerprints at various times up to 120 hr after the images were placed on the slides. Conclusive results were obtained: 139 of the 160 images (86.9%) were considered suitable for identification purposes. The method has been adopted as official final action.
Determination of Pentachlorophenol in Toy Paints
Authors: Van Langeveld Hans E A M 
Published: February 2020

Abstract
A simple procedure is described for the routine determination of pentachlorophenol (PCP) in various types of toy paints. PCP can be determined in water colors, body colors, showcard paints, gouache paints, and colored inks. PCP is extracted from the sample with acetone, followed by quantitative gas chromatographic analysis of the concentrated acetone extract on stainless steel columns containing 15% Carbowax 20M on 60–80 mesh Chromosorb P (AW). As little as 1 ppm PCP can be determined with recoveries ranging from 70 to 100%, depending on the type of paint. The presence of PCP in samples is confirmed by thin layer chromatography, using dansyl chloride as a fluorescent labeling compound. By this method as little as 4 ppm can be determined. The results of PCP determinations in 65 commercial samples are presented.
Collaborative Study of the Gravimetric Method for the Determination of Mercury in Chlorinated Pesticide Formulations
Authors: Launer James E 
Published: February 2020

Abstract
The official first action AOAC gravimetric method for mercury, 6.C01–6.C03, and the official CIPAC titrimetric method, M2.3, were collaboratively studied by 4 CIPAC laboratories, using the same 4 samples analyzed by AOAC collaboration in 1972. Averages at the 3.7 and 3.4% level were the same by both methods whereas the CIPAC method produced, on the average, 4% higher results, all levels included. The AOAC method performs well in the presence of copper and chlorinated pesticides and is less complex to use than the present CIPAC method for mercury in these mixtures. The method has been adopted as official final action.
A Screening Method for Sulfonamides Extracted from Animal Tissues
Authors: Phillips Wendell F , Trafton John E 
Published: February 2020

Abstract
A screening method for the estimation of possible residues of sulfonamides in poultry tissues is described. The method utilizes thin layer chromatography (TLC) to separate Bratton-Marshall positive reactants. In the absence of interference and the identification of 1 sulfonamide by TLC, the colorimctric method is recommended for quantitation. When interferences are present, TLC should be used for both qualitative and quantitative analysis. The screening method has a sensitivity of less than 0.05 ppm and a recovery of greater than 80%.
Identification of the iV-Methylated Analogs of the Hallucinogenic Amphetamines and Some Isomers
Authors: Bailey Keith , By Arnold W , Legault Donald , Verner Denise 
Published: February 2020

Abstract
The drugs 2-, 3-, and 4-methoxy-iV-methylamphetamine, 3-methoxy-4,5-methyIenedioxy- JV-methylamphetamine, and 3,4-methylenedioxy- /V-methylamphetamine are identified by spectroscopic techniques. The ultraviolet and mass spectra of isomers are similar, but proton magnetic resonance and infrared spectra are distinctly different, and reference spectra and data are provided. Gas-liquid and thin layer chromatographic systems for the analysis are discussed.
Quantitative Fluorodensitometric Determination and Survey of Aflatoxins in Nutmeg
Authors: Beljaars Paul E , Schumans Jan C H M , Koken Paul J 
Published: February 2020

Abstract
A study is presented for the quantitative fluorodensitometric analysis of aflatoxins in spices, in particular nutmeg (Semen myristicae). Samples were extracted with chloroform, followed by silica gel column cleanup according to the AOAC official first action method, 26.019(a), and by 2-dimensional thin layer chromatography according to the antidiagonal technique. The method includes a confirmatory test for aflatoxins by hemiacetal formation. The concentrations of aflatoxins in samples were determined by measurement of the fluorescent intensities of the separated aflatoxin spots from sample and standards on the same chromatoplate with a reflectance flying-spot densitometer. With such a technique, a coefficient of variation value of 5.22±1.24% (P &lt; 99%) was calculated for a series of 5 standard B, spots and averaged for 13 TLC plates, demonstrating the precision of the chromatographic and densitometric procedures. An average recovery of 108.4±5.8% (P &lt; 95%) was obtained for 11 spiked nutmeg extracts (5.0–20.0 μg B1 added/kg), whereas an average recovery of 92.6±4.9 (P &lt; 95%) was established for 13 spiked nutmeg samples (5.0–20.0 μg B1 added/kg). The coefficient of variation of the complete analytical procedure for ground nutmeg was 8.80%. In a survey on the occurrence of aflatoxins in 40 commercial nutmeg samples (covering 12 different brands) in The Netherlands, aflatoxins were detected in 30 ground samples (32 ground samples analyzed) in concentrations ranging from 1.0 to 23.2 μg B1/kg or from 2.7 to 36.5 μg B1 + B2 + G1 + G2/kg, whereas no aflatoxins were present in whole nutmeg kernels (8 samples analyzed). The lowest level of detection was 1.0 μB1/kg. In addition, 50 commercial spices consisting of 19 different types of commodities other than nutmeg were assayed for aflatoxins according to the same procedure. No aflatoxins were detected in these samples, with the exception of 1 sample of bay leaf which contained 5.1 μg B1/kg.
Quantitative Determination of FD&C Colors in Foods
Authors: Graichen Charles 
Published: February 2020

Abstract
A published procedure using Amberlite LA-2 (a liquid anion exchange resin) solutions to extract colors from food and the salt solution cellulose chromatographic technique to separate colors from each other were updated and submitted to collaborative study. Three batches of cookies and 4 purchased products were analyzed by 13 collaborators. The 3 batches of cookies contained different color mixtures requiring the selection of various procedures. The 4 purchased products were selected principally to include a variety of foods. Some results were partially deficient. The deficiencies reflect certain inadequacies in the directions as written rather than basic flaws in the method. Some improvements were suggested by the collaborators. The Associate Referee recommends that the method be further revised to correct the present inadequacies and to include some improvements, and that the revised method be submitted to another collaborative study.
Microbiological Assay of Patulin, Using Bacillus megaterium
Authors: Stott William T , Bullerman Lloyd B 
Published: February 2020

Abstract
Bacillus megaterium 1NRRL 1368 was found to be sensitive to patulin and a suitable test organism for an accurate, quantitative bioassay of the toxin. The optimum conditions for the test were determined. The response of the organism to patulin was found to be linear between 2 and 80 μg. When compared to thin layer chromatographic and spectrophotometric assay methods, the bioassay was found to be comparable in accuracy, but less sensitive. The test was found to be sensitive to 1.7 μg patulin. The assay is rapid (12–15 hr), simple, and inexpensive and can be used to verify the toxicity of samples, as well as to quantitatively measure patulin in samples of liquid media, apple juice, and corn.
Collaborative Study of a Spectrofluorometric Method for Lasalocid Sodium in Feeds
Authors: Osadca Modest , Araujo Mercedes 
Published: February 2020

Abstract
A collaborative study has been completed on a spectrofluorometric method for determining lasalocid sodium in finished poultry feeds. After a brief treatment of feed samples with pH 4.7 buffer, the drug is extracted with ethyl acetate. The ethyl acetate extract is further cleaned up by treatment with HCI and NaOH and quantitatively measured by spectrofluorometry. Nonspecific fluorescence is corrected for via the lasalocid-boric acid complex. The method is rapid, sensitive, and free of interference. A number of other feed additives, including monensin and ethoxyquin, do not interfere. Nine collaborators participated in the study and agreement between laboratories was satisfactory. The average recoveries of lasalocid sodium from the mash feeds added at levels of 0.0064, 0.0080, and 0.0096% were 100, 98, and 99%, respectively, and the corresponding coefficients of variation were 12.8, 8.2, and 8.0% (all results included). The method has been adopted as official first action.
Column Chromatographic Analysis of Barbiturates in Their Dosage Forms. II. Secobarbital, Amobarbital, and Pentobarbital
Authors: Cunningham Catherine G , Barkan Susan 
Published: February 2020

Abstract
A general method for the analysis of barbiturates, using column partition chromatography, was extended to the assay of secobarbital, amobarbital, and pentobarbital. A solution of the barbiturate constitutes the immobile phase in the chromatographic system. It is eluted with ether-isooctane (l+9) and passed onto a K3PO4 column, which retains the barbiturate while extraneous materials are washed out. The barbiturate is removed from the column with etherisooctane (3+1), extracted from the eluate with NH3, and measured spectrophotometrically.
Evaluation of a Selective Medium for Hydrogen Sulfide Production by Salmonella
Authors: Andrews Wallace H 
Published: February 2020

Abstract
An evaluation was made of Padron-Dockstader sulfide (PDS) agar for the rapid detection of Salmonella and Arizona microorganisms in foods. Analysts from 9 Food and Drug Administration District laboratories determined the reactions of 638 Salmonella cultures, 30 Arizona cultures, and 1754 non-Salmonella and non-Arizona cultures isolated from 157 food samples in PDS agar. The degree of positive reactions of these cultures in this agar was scored on a scale of “–” to “+ + + ”. The highest percentage of Salmonella isolates (64.1%) was in the category of +++ reactions. Progressively lower percentages of Salmonella isolates occurred in the more negative reaction categories. The highest percentage of Arizona isolates (66.7%) occurred in the intermediate ++ category. The majority of non-Salmonella and non-Arizona isolates occurred in the – (41.0%) and ± (44.8%) categories. Advantages of using the PDS agar are that it is simple to use, requires no specialized training or equipment, and alerts analysts to those Salmonella cultures which produce atypical reactions in triple sugar iron agar, particularly the lactosepositive Salmonella. However, in this study the occurrence of false-negative reactions ranged from 4.3 to 13.9% for Salmonella and from 0 to 6.7% for Arizona, according to the criteria used to interpret the reactions in PDS agar,
Microbiological Turbidimetric Analysis of Low Chlortetracycline Concentrations in Feeds
Authors: Ragheb Hussein S , Porubcan Linda S 
Published: February 2020

Abstract
Recovery studies in which chlortetracycline hydrochloride (CTC-HCl) standard was added to cattle and swine feed supplements at 4.09–9.99 g/ton showed lower antibiotic recovery turbidimetrically (80.6–98.7%) than by the AOAC modified standard as in 38.179(d) (91.2–98.7%) and the plain buffer as in 38.179(b) (93.8-133.0%) methods. Three feeds fortified with a commercial premix at the levels of 5.0 and 10.0 g CTC-HCl/ton showed an overall CTC-HCl recovery of 87.6–110.6% by manual turbidimetric assay. Results were 89.1–108.7% by the AOAC inactivated feed diluent standard and 95.4–125.4% by the plain buffer methods. For some sample extracts (as in cattle feed) the use of heat to stop bacterial growth in the turbidimetric method caused formation of a precipitate. Cooling of cultures to room temperature and rapid reading of sample turbidity followed by standard curve concentrations minimized this interference. The manual turbidimetric assay of low levels of CTC-HCl in feeds appears to offer advantages over other methods.
Gas-Liquid Chromatographic Determination of Nifursol in Frozen Turkey Tissues to Ten Parts Per Billion
Authors: Frahm Larry J , George Glenn M , Mcdonnell J Patrick 
Published: February 2020

Abstract
Nifursol (3,5-dinitrosalicylic acid (5-nitrofurfurylidene) hydrazide) is extracted into ethyl acetate from 10 g tissue in the presence of sodium sulfate. Tissue interferences are removed from the tissue extract by washing with petroleum ether after the extract has been transferred into an aqueous solution by evaporation of ethyl acetate. The drug is hydrolyzed under acid conditions to form 5-nitro-2-furaldehyde (5NF). After partition of 5NF from the aqueous phase into benzene the extract is further cleaned up on a Florisil column. The 5NF is eluted from the Florisil column with benzeneethyl acetate. Electron capture gas-liquid chromatography of a 10 μl injection of the concentrated column eluate is the determinative step. Quantitation is accomplished by comparison of the peak height of the sample to the peak height of the standard which is carried through the method simultaneously. Studies of method performance on turkey muscle, liver, kidney, and skin tissues fortified to contain 10 ppb nifursol show a recovery range of 87.4–95.0% and a coefficient of variation range of 5.7–11.2%.
Analysis of Vinyl Chloride by Mass Fragmentography
Authors: Rosen Joseph D , Morano James R , Pareles Stephen R , Giacin Jack R , Gilbert Seymour G 
Published: February 2020

Abstract
Vinyl chloride is analyzed by mass fragmentography by simultaneously recording its m/e 62 and 64 ions. The minimum quantity necessary for detection is 8.7 × 10-12 g/10 ml injection. At this level the coefficient of variation is 8.51%.
Photochemical Technique for the Elimination of Chlorinated Aromatic Interferences in the Gas-Liquid Chromatographic Analysis for Chlorinated Paraffins
Authors: Friedman David , Lombardo Pasquale 
Published: February 2020

Abstract
A method is described for eliminating chlorinated aromatic interferences in the analysis for the more volatile chlorinated paraffins. Sample extracts are irradiated in aliphatic hydrocarbon solvents with high intensity ultraviolet light prior to detection of the chlorinated paraffin by microcoulometric gas-liquid chromatography. Chlorinated aromatic and unsaturated materials, including DDT and polychlorinated biphenyls, are selectively degraded to compounds containing little or no chlorine. Cycloaliphatic pesticides such as toxaphene, chlordane, and mirex are only partially degraded. Analysis of fish fillets fortified with 1 and 5 ppm of a chlorinated paraffin gave recoveries &gt;90%.
Determination of 4,4’-(Diazoamino)-dibenzenesulfonic Acid in FD&C Yellow No. 6
Authors: Marmion Daniel M 
Published: February 2020

Abstract
Gravity column chromatographic and highpressure liquid chromatographic (HPLC) methods were evaluated for the determination of 4,4’-(diazoamino)-dibenzenesulfonic acid in FD&C Yellow No. 6. HPLC proved to be the superior of the 2 techniques tested and is recommended for further study.
A Quantitative Method for Determination of Aflatoxin B1 in Roasted Corn
Authors: Shannon Gail M , Shotwell Odette L 
Published: February 2020

Abstract
Roasting aflatoxin-contaminated corn will reduce toxin levels. A quantitative analysis for aflatoxin in roasted corn has been developed by modifying a cleanup technique for green coffee extracts approved as official first action by the AOAC. A chloroform extract is partially purified on a Florisil column, and thin layer chromatographic (TLC) plates are developed with methylene chloride-chloroform-isoamyl alcoholformic acid (81+15+3+1). Recoveries average 101% and the sensitivity limit is 5 ppb aflatoxin B1 A 2-dimensional TLC procedure can also be used to separate the aflatoxins from background interferences.