bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Polysorbates in Foods by Colorimetry with Confirmation by Infrared Spectrophotometry, Thin-Layer Chromatography, and Gas Chromatography
Authors: Kato Haruyasu , Nagai Yuji , Yamamoto Katsuhiko , Sakabe Yoshio
Published: February 2020

A method is presented for the detection of polysorbates (PSs) in 8 kinds of processed foods by colorimetric and thin-layer chromatographic (TLC) techniques. The PSs are extracted from processed foods with a mixture of methylene chloride and ethanol by using an Extrelut column. The extract is further purified by using a silica gel column. The PS extract is complexed with cobalt-thiocyanate (Cothiocyanate) reagent and is determined spectrophotometrically at 620 nm. The recoveries and coefficients of variation for 8 kinds of processed foods fortified with 0.1% PS 80 were 67.9-94.6% and 4.0- 11.3%, respectively. The detection limit of TLC corresponded to 50 mg PS 80/kg. PS identity was confirmed by infrared spectrophotometry of PS extract, and gas chromatography of fatty acids and thin layer chromatography of POE-sorbitan residues after saponification.
Determination of Aspartame in Beverages Using an Alcohol Oxidase Enzyme Electrode
Authors: Smith Vicki J , Green Richard A , Hopkins Thomas R
Published: February 2020

A new method for the determination of the artificial sweetener aspartame is described. α-Chymotrypsin is used to cleave the methyl ester group of aspartame, producing methanol hydrolytically. The methanol is detected using an electrode which is constructed by physically trapping yeast alcohol oxidase enzyme at the tip of a dissolved oxygen electrode. The decrease in oxygen concentration, which occurs as methanol is enzymatically oxidized to formaldehyde, is measured amperometrically. Aspartame levels in diet soft drinks as determined by the proposed method and by liquid chromatography are in excellent agreement. The relative standard deviation of the measurements is 0.83%. The methanol present in diet cola as a result of aspartame degradation can also be measured by using the electrode without α-chymotrypsin.
Development of Serological Ovine Field Test (SOFT) by Modified Agar-Gel Immunodiffusion
Authors: Cutrufelli Mark E , Mageau Richard P , Schwab Bernard , Johnston Ralph W
Published: February 2020

A serological ovine field test (SOFT) has been developed for detection of lamb or sheep tissue in a wide variety of raw meat products. The test is an adaptation of previously developed field screening immunodiffusion tests for beef, poultry, and pork detection. The SOFT test was demonstrated to be specific, sensitive, and accurate in the analysis of 104 samples.
Colorimetric Determination of Tetracycline Derivatives in Pharmaceutical Preparations
Authors: Saha Utpal
Published: February 2020

A quick colorimetric method is reported for the determination of tetracycline derivatives such as oxytetracycline hydrochloride (OTCH), chlortetracycline hydrochloride (CTCH), methacycline hydrochloride (MCH), and doxycycline hydrochloride (DCH). The method involves complexation of the above derivatives with cupric chloride in alkaline medium. The yellowish green copper complexes of OTCH, CTCH, MCH, and DCH show maximum absorbance at 395, 410, 400, and 400 nm, respectively. The color intensity obeys Beer's law in the concentration range of 0-20 μg/mL.
Liquid Chromatographic Determination of Seven Antioxidants in Dry Foods
Authors: Page B Denis , Charbonneau Claudette F
Published: February 2020

The liquid chromatographic determinative step of the official method for propyl gallate, trihydroxybutyrophenone, tert-butylhydroquinone, nordihydroguaiaretic acid, butylated hydroxyanisole (BHA), 3,5-di-tert-butyl-4-hydroxymethylphenol, and butylated hydroxy toluene (BHT) in fats and oils has been applied to their determination in a number of dry foods. A representative sample (10 g) is homogenized first with hexane (25 mL), then with 5 mL added water, and finally with 75 mL added acetonitrile. The hexane and acetonitrile are decanted, filtered, and separated; the hexane and rehydrated food are reextracted with 2 additional portions of acetonitrile, and the combined acetonitrile extracts are concentrated and diluted to 10 mL. An aliquot is analyzed as described in the official method, using a 150 X 4.6 mm 5 μm C-18 column. The need for rehydration to maximize the recovery of BHA and other antioxidants from marketplace dry food samples such as potato flakes, dry coffee whiteners, and dessert topping mixes was demonstrated. Rehydration was not required for cheese snacks, breakfast cereals, cake mixes, and some other foods. The need for rehydration should be determined by analyzing other foods with and without the addition of water. Potato and corn chips, popcorn and cheese snacks, breakfast cereals, dry beverage mixes, rice, potato flakes, french fried potatoes, and cake mixes were spiked with the above antioxidants at 10-50 ppm. Overall recoveries ranged from 64.3 to 105.6% and repeatabilities ranged from 0.7 to 10.8%. A total of 109 samples of the above foods were analyzed, and 64% contained detectable (> 1-2 ppm) antioxidants, mainly BHA and BHT.
Comparison of the Ion Exclusion Chromatographic Method with the Monier-Williams Method for Determination of Total Sulfite in Foods
Authors: Kim Hie-Joon
Published: February 2020

Experimental data comparing the alkali extraction/ion exclusion chromatographic method with the Monier-Williams method for determination of total sulfite are presented in (a) enzymatic and nonenzymatic browning systems, (b) vegetables containing naturally occurring sulfite, and (c) a carbohydrate-type food additive, erythorbic acid. Excellent agreement, with a linear correlation coefficient of 0.99, was observed in fresh potato samples homogenized with sulfite and allowed to react for different time intervals (enzymatic browning system). A good overall correlation was observed in dehydrated, sulfited apple samples heated for different times (nonenzymatic browning system); however, as heating time increased, higher results were obtained by the Monier-Williams method than by the alkali extraction/ion exclusion chromatographic method. The results of determining sulfite in the alkali trapping solution following acid distillation or acid treatment without heat suggested that this deviation was due to a fraction of sulfite bound to the browning reaction products in such a way that it was released by acid distillation but not by alkali extraction or acid treatment without heat. Similar behavior was demonstrated in cabbage with naturally occurring sulfite, which was released by acid distillation but not by alkali extraction or acid treatment without heat. The ion exclusion chromatographic method could overcome interference by the volatile caramelization reaction products in the Monier-Williams determination of erythorbic acid.
Dry Rehydratable Films for Enumeration of Coliforms and Aerobic Bacteria in Dairy Products: Collaborative Study
Authors: Curiale Michael S , Fahey Paul , Fox Terrance L , Mcallister J Sue
Published: February 2020

A collaborative study was conducted to compare proposed dry-film plating methods, using aerobic count plates and coliform count plates, to standard agar plating methods for quantifying aerobic bacteria and coliforms in dairy products. In this study, 5 food products (chocolate milk, pasteurized cheese, nonfat dry milk, evaporated milk, and vanilla ice cream), selected as representative dairy products, were analyzed by 11 collaborating laboratories. The results indicate that the dry-film plating methods are equivalent to or better than the agar plating methods. The aerobic count and coliform count dry-film plating methods have been adopted official first action.
Determination of Sterigmatocystin in Barley by Acetylation and Liquid Chromatography
Authors: Abramson David , Thorsteinson Tom
Published: February 2020

The estimation of sterigmatocystin by fluorescence liquid chromatographic analysis of the acetate derivative has eliminated the background interference normally encountered in analysis of underivatized sterigmatocystin in barley. Barley samples are extracted with acetonitrile-water; the extract is then washed with hexane, transferred to chloroform, and eluted from a silica gel column with cyclohexane- ethyl acetate. The extract is heated with pyridine and acetic anhydride for 3 h to give a stable derivative. Reverse-phase liquid chromatography, using a methanol-water mobile phase gradient and fluorescence detection, is the method of determination. Recoveries from barley samples spiked with 20,110,190, and 765 μg sterigmatocystin/ kg were 31, 69, 75, and 96%, with coefficients of variation between 2.8 and 5.4%. Sterigmatocystin is confirmed by comparing retention times in underivatized extracts of samples and standards, using methanol-water (3 + 2) mobile phase and ultraviolet detection.
Extraction of Light Filth from Spirulina Powders and Tablets: Collaborative Study
Authors: Nakashima Marvin J
Published: February 2020

Results are reported for a collaborative study of a method for the extraction of light filth from spirulina (a blue-green alga) powder and tablets. A 50 g portion of either powder or tablets is dispersed in water, and then boiled with dilute HCl solution. Hairs and insect fragments are isolated by wet sieving on a No. 230 sieve, flotation with mineral oil, and washings of the mineral oil in a percolator. Average recoveries by 12 collaborators for tablets and powders were 70.6 and 70.2%, respectively, for 10 rat hair spikes and 68.3 and 84.4%, respectively, for 20 insect fragment spikes. The method has been approved interim official first action.
Determination of Sulfites in Foods by Simultaneous Nitrogen Purging and Differential Pulse Polarography
Authors: Holak Walter , Specchio John
Published: February 2020

An improved technique has been developed for determination of sulfites in food by differential pulse polarography. A Teflon™ sleeve is fitted to the dropping mercury electrode capillary so that SO2 is purged from the sample and simultaneously detected at peak potential. Bound sulfite in the sample is released at room temperature by addition of base in the absence of oxygen. For some foods, the prepared sample was passed through a Sep-Pak C-18 cartridge to remove naturally occurring sulfur compounds so that only added sulfite is measured. The level of detection was approximately 1 μg S02/g. Results agreed with those obtained by the optimized Monier- Williams method for a variety of foods.
Liquid Chromatographic Determination of Ketoprofen and Its Related Compounds in Raw Materials, Capsules, and Enteric Coated Tablets
Authors: Beaulieu Beaulieu , Lefrancois J , Ong H , Lovering Edward G
Published: February 2020

A liquid chromatographic method for the determination of ketoprofen and 6 known related compounds has been developed. The lower limit of quantitation of the related compounds in the drug is 0.05% or less for all compounds, and the precision of the drug assay method is about 1.5%. The highest levels of impurities found in 3 drug raw material samples and 4 solid oral dosage formulations were 1.37 and 0.43%, respectively.
Simultaneous Determination of Oxytetracycline, Tetracycline, and Chlortetracycline in Milk by Liquid Chromatography
Authors: Thomas Michael H
Published: February 2020

A simple, rapid procedure is described for the simultaneous quantification of 3 tetracycline drugs in bovine milk. Samples are prepared by dilution with an EDTA/phosphate buffer solution and filtration through a molecular weight cutoff filter. Analytes are concentrated on-column using a reverse-phase gradient elution system of oxalic acid, acetonitrile, and methanol. The limits of quantitation are approximately 15-50 ng/mL and the limits of detection are 10-20 ng/ mL, depending on the compound. For oxytetracycline, over the range 50-1200 ng/mL, the average recovery and intralaboratory coefficient of variation were 97% and 4.1%, respectively. Over the same range, these parameters were, respectively, 97% and 5.0% for tetracycline, and 89% and 6.4% for chlortetracycline. The applicability of this procedure is demonstrated by separation and detection of incurred tetracycline residues in milk from treated animals.
Regulatory Approach to Determination of Lysine in Feedstuffs by Liquid Chromatography with Fluorescence Detection via Precolumn Dansylation
Authors: Thio Alan , Tompkins David H
Published: February 2020

A method for compliance analysis for total lysine in animal feed is described. One g portions of finely ground feed sample are spiked with a calculated amount of diaminobutyric acid internal standard and hydrolyzed by heating with 100 mL 6N aqueous HC1 at 120°C in a closed bottle. A very small aliquot (25 /*L) of hexane-washed hydrolysate is evaporated under vacuum to dryness and derivatized with dansyl chloride. Lysine is separated from other amino acids by isocratic reverse-phase (LC-18) liquid chromatography; the mobile phase is acetonitrile-O.OlM sodium phosphate (pH 7.0) buffer (100 + 210, v/v). The internal standard method along with a fluorescence detector (310-410 nm excitation and 435-650 nm emission), is used for quantitation. Thirty-five feed samples of various types (lysine 0.2- 8.2%) were analyzed with no interference from the matrix. The results were compared with those furnished by an independent laboratory using an amino acid analyzer; no statistical difference was found at the 95% confidence level. Six replicate analyses of a feed sample showed a coefficient of variation of 2.8%; no significant differences were found when between-day results of 9 samples (lysine 0.90- 4.30%) were compared. This procedure has been tested for ruggedness and can be applied for compliance determination of total lysine in feedstuffs by laboratories with limited resources
Evaluation of Various Methods for Measurement of Pectin Content in Jam
Authors: Carbonell Elvira , Costell Elvira , Durán Luís
Published: February 2020

Suitability, precision, and accuracy of 3 colorimetric methods to measure pectin content in fruit jams are examined. The methods resolve non-uronide interferences in different ways: (1) with 3,5-dimethylphenol colorimetric reagent, and absorbance differences measured at 450 and 400 nm; (2) with m-hydroxydiphenyl colorimetric reagent, and numeric correction of sample blank to compensate for interferences; and (3) with m-hydroxydiphenyl colorimetric reagent and removal of interferences by purification of sample pectins. The 3,5-dimethylphenol method is not suitable when fructose is present. Precision and accuracy of the second method are not satisfactory because sugar/pectin ratio in jam samples is very high. The third method is recommended because the precision (0.9% < CV < 6.4%) is good and recovery is nearly 100%.
Multiresidue Method for Isolation and Liquid Chromatographic Determination of Seven Benzimidazole Anthelmintics in Milk
Authors: Long Austin R , Hsieh Lily C , Malbrough Marsha S , Short Charles R , Barker Steven A
Published: February 2020

A multiresidue method for the isolation and liquid chromatographic determination of 7 benzimidazole anthelmintics (thiabendazole, oxfendazole, para-hydroxyfenbendazole, fenbendazole sulfone, mebendazole, albendazole, and fenbendazole) in milk is presented. Blank or benzimidazole-spiked milk samples (0.5 mL) were blended with octadecylsilyl (C-18, 18% load, end-capped) derivatized silica packing material. A column made from the C-18/milk matrix was first washed with hexane (8 mL), and then the benzimidazoles were eluted with methylene chloride-ethyl acetate (1 + 2, v/v; 8 mL). The eluate contained benzimidazole analytes which were free from interfering compounds as determined by UV detection (photodiode array, 290 nm). Correlation coefficients of standard curves for individual benzimidazoles isolated from spiked samples were linear (0.989 ± 0.003 to 0.998 ± 0.001) with recoveries ranging from 70 ± 9% to 107 ± 2% for the concentration range (62.5-2000 ng/mL) examined. The inter- assay variabilities ranged from 4 ± 1% to 9 ± 7% with intra-assay variabilities of 3-6%.
Optimized Gel Permeation Chromatographic Cleanup for Soil, Sediment, Wastes, and Oily Waste Extracts for Determination of Semivolatile Organic Pollutants and PCBs
Authors: Czuczwa Jean M , Stevens Ann Alford
Published: February 2020

A gel permeation chromatographic (GPC) method, used by the U.S. Environmental Protection Agency (USEPA), was modified for cleanup of soil, sediments, wastes, and oily wastes before determination of semivolatile organic pollutants. The modifications included new calibration procedures and control of the amount of material processed. The modifications were evaluated for soil and sediment matrixes in a 5-laboratory study where each laboratory processed a solution containing a phthalate, substituted phenols and benzenes, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), nitroaniline, and pesticides. With the exception of nitroaniline, analyte recoveries were 87-112%, with relative standard deviations (RSDs) of 6.7-26%. Soil samples containing PCBs and fortified with 6 pesticides at 0.7-4 /ig/g were also analyzed by the 5 laboratories. The mean recovery of the 6 pesticides was 100% with a mean RSD of 16%. Mean RSD for the determination of total PCBs was 8.9%. An additional modification for the processing of wastes and high concentration waste samples was attempted; this involved GPC processing of sample extracts dissolved in 1 + 1 butyl chloridemethylene chloride. This modification did not improve recoveries of the semivolatile analytes. Finally, the modified GPC protocol was applied to PCB-contaminated reclaimed waste oils samples. Two GPC cleanup steps were used to separate PCBs from the waste oil samples before PCBs were determined by gas chromatography combined with electron-capture detection (GC/ECD).
Determination of Organic Acids in the Presence of Metal Ion
Authors: Koseki Masamichi , Takahashi Iwao , Yasuno Tetsuko , Ogino Shuzo , Tsuda Yuko , Kazama Masayoshi
Published: February 2020

The recovery of organic acids: citric, tartaric, fumaric, succinic, and malic, was examined by liquid chromatography in the presence of calcium, magnesium, or aluminum ions. Calcium and magnesium ions, i.e., ions of valence +2, did not interfere in determinations of the organic acids examined here. These organic acids could be determined without interference from aluminum ion by pH adjustment of the solutions to pH 2.
Comparison of Volatile Acid Number Test with Enzymatic Acetic Acid Assay for Assessment of Seafood Quality
Authors: Mccarthy Helen T , Ellis Christopher P , Silva Mary Lou , Mills Barbara
Published: February 2020

Volatile acid number, an official AOAC method for assessing seafood quality, was compared with an enzymatic method for measuring acetic acid. Thirty-eight samples of fresh fish and 23 samples of canned fish were evaluated. The data showed high positive correlations between volatile acid number and enzymatic acetic acid methods; the correlation coefficient was 0.98 for fresh fish and 0.95 for canned fish. Positive correlation coefficients of 0.93 and 0.96 were also associated with samples of fish divided into 2 groups on the basis of acceptable or unacceptable quality, respectively. There was no significant difference between the means for the volatile acid number and enzymatic acetic acid procedures at the 5% level of significance. Decomposition studies on cod and mackerel, representing a lean and fatty fish, respectively, were monitored over 9 days by using the following analyses: volatile acid number, acetic acid, total volatile bases, and thiobarbituric acid. Results of the decomposition studies showed that enzymatic acetic acid levels closely paralleled volatile acid number values in both lean and fatty fish. Total volatile bases was a reliable supplemental measure for evaluating lean seafood quality, whereas thiobarbituric acid was more appropriate for further assessment of fatty fish quality.
Capillary Column Gas Chromatographic Determination of Dicamba in Water, Including Mass Spectrometric Confirmation
Authors: Jimenez Nancy C , Atallah Yousef H , Bade Thomas R
Published: February 2020

A sensitive method is described for determining dicamba at low μg/L levels in ground waters by capillary column gas chromatography with electron-capture detection (GC-EC); compound identity is confirmed by gas chromatography-mass spectrometry (GC-MS) using selected ion monitoring. Dicamba residue is hydrolyzed in KOH to form the potassium salt. The sample is then extracted with ethyl ether which is discarded. The aqueous phase is acidified to pH < 1 and extracted twice with ethyl ether. The combined ethyl ether extracts are concentrated, and the residue is methylated using diazomethane to form the corresponding dicamba ester. The derivatized sample is cleaned up on a deactivated silica gel column. The methylated dicamba is separated on an SE-30 capillary column and quantitated by electron-capture or mass spectrometric detection. Average recoveries (X ± SD) for ground water samples fortified with 0.40 μg/L of dicamba are 86 ±5% by GC-EC and 97 ± 7% by GC-MS detections. The EDL (estimated detection limit) for this method is 0.1 μg dicamba/L water (ppb).
Monitoring of Fertilizer Plant Effluents for Phosphorus, Sulfur, and Metals Using Inductively Coupled Plasma Emission Spectrometry
Authors: Ardis Jimmie D , Baker Alice M
Published: February 2020

At present, the U.S. Environmental Protection Agency (EPA) lists total P, F, and total suspended solids as effluent limitations for fertilizer manufacturing point source discharges. Other contaminants, including metals, may be added on a plant-by-plant permitting basis. EPA test method 200.7 lists 25 metals that may be determined by inductively coupled plasma (ICP) emission spectrometry as dissolved, suspended, or total elements in drinking and surface waters and domestic and industrial wastewaters. A method to measure a large number of these metals, as well as phosphorus and sulfur in fertilizer plant effluent water, by ICP spectrometry is described. The ICP spectrometer offers quick, sensitive, and accurate determinations for all species of phosphorus and sulfur. Total P can be determined regardless of the species present (lower oxides, ortho, poly, or organic), and sensitivity to phosphorus (0.08 /μg/mL) is greater than for most other methods. Sensitivity to sulfur (0.1 /μg/mL) also is greater than for most other methods and can be determined as total, sulfate, sulfide, or sulfite by controlling sample preparation. The present paper addresses only the measurement of total S because methodology has not been completed for other species.
Comparison of Traacs 800 Autoanalyzer with Official Methodology for Total and Available Phosphorus in Fertilizer
Authors: Kane Peter F , Orcutt Anne L , Huber Janet H
Published: February 2020

A third generation of continuous flow analyzers, the Traacs 800, as configured for total P2O5 in fertilizers, was compared to the traditional gravimetric methodology. A t-test of routine samples gave t = -1.01 with 23 DF, indicating no significant difference at the 95% confidence level. The average bias, gravimetric minus analyzer, was -0.03% P2O5. The instrument configured for available P2Os was also compared to second generation AAII instrumentation. Bias was shown to exist in both instruments, which could be overcome by use of matrix standards. When routine samples were extracted and compared on the 2 instruments using matrix standards, a t-test gave t = —1.54 with 26 DF, indicating no significant difference. The average bias, Traacs minus AAII, was -0.06% P2O5. Official AOAC method status will be pursued for both Traacs methodologies.
Gas Chromatographic Determination of Nicotine in Environmental Tobacco Smoke:
Collaborative Study
Authors: Ogden Michael W
Published: February 2020

A gas chromatographic method for determination of vapor phase nicotine in environmental tobacco smoke (ETS) was collaboratively studied by 6 laboratories. Nicotine is desorbed from XAD-4 sample tubes with ethyl acetate containing triethylamine and determined by gas chromatography with nitrogen-selective detection. Each collaborator received blind duplicate samples at each of 6 nicotine concentrations. Three concentrations were generated by spiking XAD-4 tubes with known amounts of nicotine; the remaining 3 concentrations were ETS samples obtained in a carefully controlled environmental chamber containing sidestream and exhaled mainstream smoke from 1R4F Kentucky reference cigarettes. Repeatability and reproducibility relative standard deviations ranged from 4.4 to 11.1% and from 7.0 to 11.1%, respectively, for nicotine concentrations evaluated (up to 6 ng/cu m). The method has been adopted official first action.
Ethyl Carbamate Levels in Selected Fermented Foods and Beverages
Authors: Canas Benamin J , Havery Donald C , Robinson Louis R , Sullivan Michael P , Joe frank L , Diachenko Gregory W
Published: February 2020

Ethyl carbamate (EC), also known as urethane, is an animal carcinogen and a by-product of fermentation. Because EC has been found in distilled spirits and wines, a variety of fermented foods and beverages were analyzed to assess its occurrence in other products. Previously described methods using a gas chromatograph-thermal energy analyzer with a nitrogen converter were modified for each matrix and gave recoveries of >80%, with a limit of detection in the 1-2 μg/kg(ppb) range. A total of 152 test samples were analyzed; EC levels ranged from none found to 3 ppb in 15 cheeses, 6 teas, 12 yogurts, and 8 ciders; from none found to 13 ppb in 30 breads and 69 malt beverages; and from none found to 84 ppb in 12 soy sauces. Gas chromatography/mass spectrometry/mass spectrometry was used to confirm EC identity and to quantitate EC in selected food extracts
Rapid Colorimetric Determination of Activity of Subtilisin Enzymes in Cleaning Products
Authors: Klein Allan E , Freiberg John , Same Steven , Carroll Maryanne
Published: February 2020

A new colorimetric method is described for the determination of enzymatic activity of subtilisin in cleaning products. The procedure is more rapid and precise than the casein digestion methods commonly used to assay protease activity. The principle of the colorimetric method depends on the determination rate of p-nitrophenol released on hydrolysis of N-CBZ-L-leucine-/Miitrophenyl ester at pH 8.0 by subtilisin, with correction for any nonenzymatic (spontaneous) hydrolysis of the substrate. Because of the broad range of hydrolytic activity of this enzyme, and the difficulties in predicting its proteolytic activity, this hydrolytic rate was chosen as a general indicator of subtilisin enzyme behavior. The slope for 7 replicate standard curves generated over a 6 week period exhibited a relative standard deviation of 7.5%, and 8.0% for 20 replicates with an enzyme cleaning product. Papain does not interfere with this assay.
Precolumn Phenylisothiocyanate Derivatization and Liquid Chromatography of Amino Acids in Food
Authors: Hagen Steven R , Frost Beverly , Augustin Jorg
Published: February 2020

A precolumn phenylisothiocyanate derivatization method is described for the determination of amino acids in protein hydrolysates from a wide variety of complex food matrixes, with and without performic acid oxidation pretreatment. Analysis of samples that were not pretreated with performic acid was necessary since this pretreatment destroyed an average of 25% of the histidine and 87% of the tyrosine present in the food samples. This method is rapid and reproducible; coefficients of variation between duplicate analyses of the same food item were less than 5% for a majority of the amino acids. Occasionally, variation between duplicate analyses for histidine and tyrosine was greater than 10%. Recoveries of amino acids added to samples were in the 100% range.
Spectrophotometric Method for Microdetermination of Nitrogen in Kjeldahl Digest
Authors: Devani Muljibhai B , Shishoo Chamanlal J , Shah Shailesh A , Suhagia Bhanubhai  N
Published: February 2020

A new spectrophotometric method for the determination of nitrogen in Kjeldahl digest has been developed. The method is based on the reaction of ammonia with acetylacetone-formaldehyde reagent in aqueous medium to yield yellow 3,5-diacetyl- 1,4-dihydrolutidine with a characteristic absorption maxima at 412 nm. The effect of several experimental variables on the determination of nitrogen was studied. The method was suitable for determination of nitrogen in acidic medium without interference from the usual catalysts employed for the digestion in Kjeldahl method. Lambert-Beer’s law is obeyed in the concentration range of 0.5-6.0 ng nitrogen/mL in the reaction mixture. The molar absorptivity in terms of nitrogen was 1.4 X 103L mol-1 cm-1. The standard deviation and relative standard deviation were ±0.0447 and ±0.896% (n = 10), respectively. The method is simple, rapid, and precise. A variety of carbocyclic and heterocyclic nitrogen compounds have been analyzed for nitrogen content. The results are comparable with those obtained by AOAC method, 47.021.
Comparison of Two ELISA Screening Tests with Liquid Chromatography for Determination of Aflatoxins in Raw Peanuts
Authors: Dorner Joe W , Cole Richard J
Published: February 2020

A study was conducted to evaluate the performance of 2 enzymelinked immunosorbent assays (ELISA) for rapidly screening samples of peanuts for the presence of aflatoxin. The EZ-Screen Quick Card Test and the Afla-10 Cup Test were compared with liquid chromatography in duplicate analyses of common extracts of peanuts contaminated in the range of 0-70 ppb (ng/g). Each assay properly identified 95% of samples containing no detectable aflatoxin as negative and >97% of samples containing >10 ppb aflatoxin as positive. The card test, which had a 20 ppb detection threshold, identified as positive 32 of 34 samples in the 11-20 ppb range. This indicates that the card test might actually have a detection threshold closer to 10 ppb. Most of the errors associated with the assays occurred on samples containing <10 ppb aflatoxin. The cup and card tests identified 76 and 67% of the samples, respectively, as negative, in the range of 4-10 ppb. For samples either negative or contaminated above their detection thresholds for the assays, the methods are well suited for use as rapid screening tests.
Monoclonal Antibody-Based Enzyme Linked Immunosorbent Assay of Aflatoxin B1, T-2 Toxin, and Ochratoxin A in Barley
Authors: Ramakrishna Nannapaneni , Lacey John , Candlish Alan A.G , Smith John E , Goodbrand Ian A
Published: February 2020

Aflatoxin B1 (B1), T-2 toxin (T2), and ochratoxin A (OA) were assayed in a single extract from barley grain by using competitive enzyme linked immunosorbent assays (ELISAs) with monoclonal antibodies. B1 and T2 monoclonal antibodies were conjugated to horseradish peroxidase for direct competitive ELISA while an indirect competitive ELISA was used for OA determination. The competitive ELISA detected 0.1 ng/mL of B1f 10 ng/mL of T2, or 1 ng/mL of OA. Acetonitrile- 0.5% KCI-6% H2S04 (89 + 10 + 1 ) extracts of barley grain either were diluted 1:10 for direct assay or were subjected to a simple liquid-liquid cleanup procedure to concentrate the extract 10:1 before assay. For cleanup, water was added to the acetonltrile extract to partition water-soluble interfering substances, and then the mycotoxins were re-extracted with chloroform. The chloroform extract was evaporated to dryness and redissolved in Tris HCI buffer for ELISA. The mean recoveries from barley spiked with 4-60 ng/g of B1( 50-5000 ng/g of T2, and 5-500 ng/g of OA were, respectively, 93.8, 80.6, and 95.8%. The mean within-assay, Inter-assay, and subsample coefficients of variation by ELISA of barley grain colonized with toxigenic fungi were <12% for Bi and OA but as high as 17% forT2.
Diagnostic Data Evaluation. Part II. Collaborative Study Evaluation: Coefficient of Variation Considered To Be A Constant
Authors: Malanoski Anthony J
Published: February 2020

The principles described in Part I were used to determine standards of performance for the method and for analysts from a collaborative study of the determination of nitrosopyrrolidine (NPYR). Performance standards for the method were 10.4% RSDa, 9.2% for RSDo, and 14.2% for RSDx.
Polymeric Film Dialysis in Organic Solvent Media for Cleanup of Organic Contaminants
Authors: Huckins James N , Tubergen Mark W , Lebo Jon A , Gale Robert W , Schwartz Ted R
Published: February 2020

Dialytic enrichment, using a nonpolar polymeric film or membrane, is proposed as a new approach for the separation of organic contaminants from fish lipid. Nonpolar organochlorine analytes diffuse from the fish lipid through a polyethylene membrane into cyclopentane. Separations of 48 h or less in duration afforded excellent recoveries for all analytes tested and removed 93% of the fish oil. Kinetics of membrane diffusion and possible controlling factors are elucidated for selected analytes and model compounds. Potential advantages of this technique over conventional lipld-removal methods such as gel permeation chromatography include simplicity, large sample capacity, reduced solvent requirements, and amenability to interfacing in-line with other enrichment modules.
Extraction of Gasoline Constituents from Soil
Authors: Donaldson Susan G , Miller Glenn C , Miller W W
Published: February 2020

The recovery of gasoline constituents from soil by using a sonication/extraction method was evaluated. Ten characteristic compounds were studied: benzene, toluene, n-heptane, m-xylene, nonane, n-propylbenzene, 1,2,4-trimethylbenzene, n-butylbenzene, 1,2,4,5-tetramethylbenzene, and dodecane. Modifications of extraction method EPA 3550 were tested using flame ionization gas chromatography with a 15 m X 0.53 mm id fused-silica capillary column. For dry soils, reducing total solvent extraction volume from 400 to 250 mL resulted in equivalent recoveries and shorter analysis times. Recovery of the gasoline constituents from wet soils was significantly lower than from dry soils for all methods studied. Recoveries were also dependent on the relative constituent volatility. Higher molecular weight compounds were recovered at greater than 80% of the initial amount applied from dry soils; while recoveries of benzene and heptane were generally less than 5%. Using the most efficient extraction procedure, recovery of unleaded gasoline from a dry, spiked soil was 43.2% when expressed on a total petroleum hydrocarbon basis, and recovery from a wet, spiked soil was 21.8%.
Capillary Gas Chromatographic Method for Determination of Benzylpenicillin and Other Beta-Lactam Antibiotics in Milk
Authors: Meetschen Ute , Petz Michael
Published: February 2020

A capillary gas chromatographic method Is described for determining residues of beta-lactam antibiotic residues In milk, with specificity for benzylpenlclllln (penicillin G), phenoxymethylpenlcillin, methlclllln, oxacillin, cloxaclllln, dlcloxaclllln, and nafclllln. Residues are extracted from milk with acetonitrlle. Samples are cleaned up by partitioning between aqueous and organic phases at different pH values. The penicillin residues are methylated with dlazomethane to render them amenable to determination by gas chromatography on a methyl silicone fused silica column. Samples are introduced by spllt/splltless injection using a programmed temperature vaporization injector and are detected by nitrogenselective thermionic detection, internal standardization Is used for quantitation. The limits of detection for all penicillins are well below 1 /μg/kg. Recoveries of spiked samples at 3 and 10 μg/kg are in the range of 42-85% (coefficients of variation 2-5%) and 41-92% (coefficients of variation 3- 7%), respectively.
Matrix Solid-Phase Dispersion (MSPD) Isolation and Liquid Chromatographic Determination of Oxytetracycline, Tetracycline, and Chlortetracycline in Milk
Authors: Long Austin R , Hsieh Lily C , Malbrouh Marsha S , Short Charles R , Barker Steven A
Published: February 2020

A multlresldue method for the isolation and liquid chromatographic determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycllne (CTC) antibiotics In milk Is presented. Blank and tetracycline (OTC, TC, and CTC) fortified milk samples (0.5 mL) were blended with octadecylsllyl (C18, 40 /an, 18% load, endcapped, 2 g) derivatized silica packing material containing 0.05 g each of oxalic acid and dlsodlum ethylenedlamlnetetraacetlc. A column made from the C18/milk matrix was first washed with hexane (8 mL), following which the tetracyclines were eluted with ethyl acetate-acetonltrlle (1 + 3; v/v). The eluate contained tetracycline analytes that were free from Interfering compounds when analyzed by liquid chromatography with UV detection (photodiode array, 365 nm). Correlation coefficients of standards curves for Individual tetracycline isolated from fortified samples were linear (from 0.982 ± 0.009 to 0.996 ± 0.004) with average percentage recoveries from 63.5 to 93.3 for the concentration range (100,200,400,800,1600, and 3200 ng/ mL) examined. The Inter-assay variability ranged from 8.5 ± 2.4% to 20.7 ± 13.0% with an Intra-assay variability of 1.0- 9.3%.
Automation Of Dihydroxyaluminum Sodium Carbonate Analysis In Antacid Tablets By Energy Dispersive X-Ray Fluorescence
Authors: Georgiades Constantine A
Published: February 2020

A sensitive, specific, automated energy dispersive X-ray fluorescence (EDXRF) method for determination of anhydrous dihydroxyaluminum sodium carbonate in antacid tablets has been developed. The compound was quantltated by Impact grinding, palletizing at 10 tons pressure, and monitoring the aluminum by using a rhodium anode X-ray tube, high resolution thermoelectrlcally cooled SI(LI) detector with sample spinning, and computer data processing. The assay procedure was validated with spiked laboratory-prepared samples at 100 ± 20% levels. The average recovery was 100.6% with a relative standard deviation of 1.6% (n = 14). Instrument precision was determined and found to have an average relative standard deviation of 1.0% (n = 16). In addition, analysis precision by the EDXRF method was compared to that for titration and autoanalyzer methodologies and found to be statistically comparable. The sample precision had an averaged relative standard deviation of 2.7% (n = 16) by X-ray methodology. The advantages of this EDXRF method Include Increased sample throughput with excellent precision and accuracy, no solvent usage, and automated data handling.
Diagnostic Data Evaluation. Part III. Collaborative Study Evaluation: Standard Deviation Considered To Be A Constant
Authors: Malanoski Anthony J
Published: February 2020

The diagnostic evaluation of the crude protein collaborative study Identified possible problems with a standardized Interval for the Kjeldahl digestion, with sample preparation, and with excess sample weights. The standard deviations for the ham and the beef samples cannot be considered to be representative of the method because of these problems. The standard deviations for the frankfurter and the pork sausage samples for all analysts met the performance standard of 0.24. There was no evidence of analyst bias.
Comparative Study of Colorimetric DNA Hybridization Method and Conventional Culture Procedure for Detection of Salmonella in Foods
Authors: Chan Samuel W , Wilson Stephen G , Vera-Garcia Marcela , Whippie Kevan , Ottaviani Margaret , Whilby Anna , Shah Alpa , Johnson Andrew , Mozola Mark A , Halbert Donald N
Published: February 2020

A second generation nucleic acid hybridization assay has been developed and evaluated against the conventional culture method for detection of salmonellae In foods. The assay Involves a liquid hybridization with Sa/mone/fo-speclflc oligonucleotide probes, capture of probe:target hybrids onto a solid support (plastic dipstick), and a colorimetric end point detection. The assay can be completed In 2.5 h, following approximately 44 h of culture enrichment. One thousand samples representing 20 food types were analyzed in parallel by both methods. Samples Included unlnoculated test product, and product Inoculated with Salmonella at 2 levels. Eighteen Salmonella serotypes were used as Inocula. The data demonstrate that the colorlmetric hybridization method and the conventional culture method are equivalent In their ability to detect Salmonella contamination of foods.
Liquid Chromatographic Method for Determination of Oxydemeton-Methyl in Formulated Products: Collaborative Study
Authors: Slahck Stephen C
Published: February 2020

A liquid chromatographic method has been developed for the determination of oxydemeton-methyl (Metasystox-RR) In formulated products. Samples are dissolved In acetonltrile and analyzed by reverse-phase chromatography using methyl paraben as an Internal standard. Twelve laboratories participated In a collaborative study of the method. Each collaborator was furnished with reference standard, Internal standard, and blind duplicate samples of Metasystox-R 50% concentrate (MSR 50 Cone), Metasystox-R spray concentrate (MSR SC), and DYLOXR/MSR 1.5-0.5 formulations. Collaborators were instructed to use peak area measurements for quantitation. Relative standard deviations for reproducibility (RSDR) were 1.44, 2.14, and 3.63%, respectively. The method has been approved Interim official first action by AOAC.
Extraction Methods for Quantitation of Gentamicin Residues from Tissues Using Fluorescence Polarization Immunoassay
Authors: Brown Scott Anthony , Newkirk David R , Hunter Robert P , Smith Gary G , Sugimoto Kyoko
Published: February 2020

Sodium hydroxide digestion of unhomogenlzed kidney and skeletal muscle for 20 min at 70°C was a superior method for extracting gentamicin from tissues, compared with simple homogenlzatlon, trichloroacetic acid precipitation of homogenized tissue, and sodium hydroxide digestion of homogenized tissue. Fluorescence polarization Immunoassay was used to quantltate gentamicin. Sodium hydroxide digestion of unhomogenlzed tissue allowed for the recovery of 90.0 ± 5.9% (Ẋ ± SD) from renal cortex and 79.9 ± 3.5% from skeletal muscle. The limit of sensitivity was 17.4 ng/g kidney tissue, 15.8 ng/g digested muscle, and 39.0 ng/g digested heart. The wlthin-assay coefficient of variation (CV) at 100 ng/g kidney was 9.2%; at 500 ng/g kidney, the CV was 2.5%; and at 2000 ng/g kidney, the CV was 1.5%. The between-assay coefficient of variation was <7.5% for all concentrations from kidney, and the 99% confidence Interval at 100 ng/g kidney was 71.7-112.4 ng gentamlcin/g kidney. The wlthln-assay coefficient of variation (CV) at 100 ng/g muscle was 15%; at 500 ng/g muscle, the CV was 2.6%; and at 2000 ng/g muscle, the CV was 2.3%. The between-assay coefficient of variation was <15% for all concentrations from muscle, and the 99% confidence interval at 100 ng/g muscle was 72.5-136.8 ng gentamlcin/g muscle. Gentamlcln-free milk could be distinguished from milk containing gentamicin concentrations of 10 ng/mL milk with 95 % confidence, and from milk containing concentrations of 30 ng gentamicin/mL milk with 99% confidence. Quantitative results at or below the tolerance level can be obtained within 90 min of sample acquisition using these extraction and assay methods
Liquid Chromatography-EIectrochemical Detection of Furazolidone and Metabolite in Extracts of Incurred Tissues
Authors: Parks Owen W , Kubena Leon F
Published: February 2020

One-day-old chicks were raised to maturity on a diet fortified with 0.0055% furazolidone. Analyses of tissue extracts by a liquid chromatographic-electrochemlcal detection screening procedure for nltro-contalning drugs disclosed, in addition to the parent drug, an unidentified metabolite in the liver and breast tissue of the mature birds sacrificed while on the fortified feed. No evidence of residues of the drug or metabolite was found In birds removed from the medicated feed 48 h prior to sacrifice. In view of the rapid In vivo and postmortem metabolism of the parent drug In liver tissue, the metabolite can serve as an alternative means of detecting furazolidone residues In chicken tissues.
Confirmation of Identity by Gas Chromatography/Tandem Mass Spectrometry of Sulfathiazole, Sulfamethazine, Sulfachloropyridazine, and Sulfadimethoxine from Bovine or Swine Liver Extracts after Quantitation by Gas Chromatography/Electron-Capture Detection
Authors: Matusik Jean E , Sternal Richard S , Barnes Charlie J , Sphon James A
Published: February 2020

Four sulfonamide veterinary drug residues were quantltated by electron-capture detection (ECD) after separation by gas chromatography (GC). The Identities of sulfathiazole (ST), sulfamethazine (SM), sulfachloropyridazine (SCP), and sulfadimethoxine (SDM) were confirmed In bovine or swine liver residues by tandem mass spectrometry (MS/MS). Bovine or swine liver tissues were extracted by using either the Tlshler or the Manuel-Steller cleanup. The methylated residues containing ST, SM, SCP, and SDM were separated by GC prior to MS/MS daughter ion analysis. Control tissue, control tissue fortified at 0.1 ppm, and Incurred tissue residues at approximately 0.1 ppm were analyzed for these 4 sulfonamides. A Flnnigan Model TSQ-46 operating in the chemical ionization mode was used to perform the MS/MS daughter Ion experiments. The Identities of all 4 sulfonamides were confirmed In a single GC/MS/MS analysis.
Comparison of Postcolumn Derivatization-Liquid Chromatography with Thin-Layer Chromatography for Determination of Aflatoxins in Naturally Contaminated Corn
Authors: Beaver Rodney W , Wilson David M , Trucksess Mary W
Published: February 2020

Quantitation of aflatoxins by liquid chromatography with postcolumn iodine derlvatization (LC-PCD) and fluorescence detection was compared with quantitation by the AOAC CB method, 968.22. Thirty-seven naturally contaminated corn samples were ground and then divided. One portion was extracted, and the extract was cleaned up and analyzed by thin-layer chromatography according to the CB method. The second portion was extracted and cleaned up In a similar fashion, but quantitation was by the LC-PCD method. For aflatoxin B1, concentrations ranging from 0 to 150 ng/g, results obtained by the 2 methods were fitted to a linear equation with the LC-PCD results as the dependent variable. The correlation coefficient was 0.99, the Intercept was near 0, and the slope was near 1. For aflatoxin B2, the correlation coefficient was 0.97, and the Intercept was near 0. However, the slope of the equation relating LC-PCD concentration to TLC concentration was only 0.5. We believe that this lack of equivalence between the methods for determination of aflatoxin B2 is due to overestlmatlon by the TLC method because the low levels present are near the TLC detection limit for B2.