bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Ten Gram Samples of Corn for Determination of Mycotoxins
Authors: Francis Octave J , Ware George M , Carman Allen S , Kirschenheuter Gary P , Kuan Shia S
Published: February 2020

Data were gathered, during a study on the development of an automated system for the extraction, cleanup, and quantitation of mycotoxins in corn, to determine if it was scientifically sound to reduce the analytical sample size. Five, 10, and 25 g test portions were analyzed and statistically compared with 50 g test portions of the same composites for aflatoxin concentration variance. Statistical tests used to determine whether the 10 and 50 g sample sizes differed significantly showed a satisfactory observed variance ratio (Fobs) of 2.03 for computations of pooled standard deviations; paired f-test values of 0.952, 1.43, and 0.224 were computed for each of the 3 study samples. The results meet acceptable limits, since each sample’s r-test result is less than the published value of the |t|, which is 1.6909 for the test conditions. The null hypothesis is retained since the sample sizes do not give significantly different values for the mean analyte concentration. The percent coefficients of variation (CVs) for all samples tested were within the expected range. In addition, the variance due to sample mixing was evaluated using radioisotopelabeled materials, yielding an acceptable CV of 22.2%. The variance due to the assay procedure was also evaluated and showed an aflatoxin B, recovery of 78.9% and a CV of 11.4%. Results support the original premise that a sufficiently ground and blended sample would produce an analyte variance for a 10 g sample that was statistically comparable with that for a 50 g sample.
Simultaneous Liquid Chromatographic Screening of Five Coccidiostats in Chicken Liver
Authors: Gallicano Keith D , Park Hyun , Yee John , Young Larry M , Saschenbrecker Peter W
Published: February 2020

A reverse-phase liquid chromatographic (LC) method is described for simultaneously determining 5 coccidiostats—aklomide, dinsed, ethopabate, nitromide, and zoalene in chicken liver. The method entails blender extraction of 10 g liver with ethyl acetate, column chromatography through Sephadex LH-20 and neutral alumina, and LC analysis on a C18 column with UV detection at 260 nm. The drugs were eluted from Sephadex with methanol-benzene (10 + 90), from alumina with methanol-dichloromethane (10 + 90), and from C18 with acetonitrile-water (linear gradient: 25% acetonitrile for 10 min, increasing to 55% over 15 min; flow rate 1 mL/min). Liquid chromatography was completed in 40 min and calculations were based on peak height measurements. Average recoveries of the coccidiostats from fortified liver ranged from 72 to 97%, except for dinsed, which showed a relatively constant average recovery of 57%. The detection limit for the standards was 2.5 ng on column. Levels as low as 50 ng/g were detected in fortified liver samples.
Determination of Zeranol/Zearalenone and Their Metabolites in Edible Animal Tissue by Liquid Chromatography with Electrochemical Detection and Confirmation by Gas Chromatography/Mass Spectrometry
Authors: Roybal Jose E , Munns Robert K , Morris William J , Hurlbut Jeffrey A , Shimoda Wilbert
Published: February 2020

A sensitive method is described for the determination and confirmation of zeranol and zearalenone, as well as their isomers and metabolites, in edible animal tissue. The analytes are extracted from tissue with methanol, hydrolyzed enzymatically, cleaned up by acidbase partitioning, determined by liquid chromatography (LC) with electrochemical (EC) detection, and confirmed by gas chromatography/ mass spectrometry (GC/MS). LC analysis is performed by isocratic elution with a buffered mobile phase using a Nova-Pak reverse-phase C,„ column with amperometric EC detection at +0.90 V. Capillary GC/MS analysis of the trimethylsilyl derivatives provides mass spectral confirmations.
Determination of Dextran in Raw Cane Sugar by Roberts Copper Method:
Collaborative Study
Authors: Clarke Margaret A , Godshall Mary An
Published: February 2020

A collaborative study was conducted using the Roberts copper method for the determination of dextran in raw cane sugars. Four samples were analyzed in duplicate, representing the range of dextran concentrations found in raw sugar. The overall repeatability and reproducibility coefficients of variation were 4.3 and 13.2%, respectively. The method has been adopted official first action.
Comparison of Four Thin-Layer Chromatographic Methods for the Determination of
Aflatoxins in Raisins
Authors: Boyacioglu Dilek , Gonul Meral
Published: February 2020

A study was conducted to determine the accuracy and precision of 3 AOAC methods, sees 26.026-26.031 (CB), sees 26.032-26.036 (BF), and sees 26.052-26.060 (cottonseed), and the Romer quantitative method for the thin-layer chromatographic (TLC) determination of aflatoxins B„ B2, G„ and G2 in raisins. The samples were spiked at a level of 10 Mg total aflatoxins/kg. The TLC development systems were: ether-methanol-water (94 + 4.5 + 1.5) and chloroform-acetone (9 + 1). The interaction between the 4 methods and the 2 development systems was also studied. The average recoveries were 88, 80, 75, and 93% with coefficients of variation of 14.0,10.4,14.0, and 9.6% for aflatoxin B, using the CB, BF, cottonseed, and Romer methods, respectively. Statistical analysis showed no difference in the results obtained using the 2 TLC development systems
Comparison of Stainless Steel Penicylinders Used in Disinfectant Testing
Authors: Cole Eugene C , Rutala William A , Alfano Edith M
Published: February 2020

Two brands of stainless steel penicylinders, S&L Metal Products and Fisher Scientific, were simultaneously tested to determine if they provide comparable results when used in the AOAC use-dilution method of disinfectant testing. Results showed consistently more positive tubes for the Fisher brand of penicylinders than for the S&L, regardless of the surface finish of the test cylinders.
Intercomparative Study on the Determination of Polynuclear Aromatic Hydrocarbons in Marine Shellfish Tissue
Authors: Uthe John F , Musial Charles J
Published: February 2020

Twenty-five laboratories were sent 2 materials, one an acetone powder of lobster digestive gland, the other, the oil which had been extracted during preparation of the powder. Each laboratory was requested to measure the levels of a suite of polycyclic aromatic hydrocarbons in both materials. The response was poor with only 10 laboratories submitting results. Both intra- and interlaboratory precisions were poor; the interlaboratory error was so great as to preclude statistical analysis of the error. Relative standard deviations for oil results determined by liquid chromatography ranged from 39 to 96%.
Determination of Inorganic Tin in Biological Samples by Hydride Generation-Atomic Absorption Spectrometry after Silica Gel Cleanup
Authors: Tsuda Taizo , Wada Minoru , Aoki Shigeru , Matsui Yoshihiro
Published: February 2020

A method is described for the determination of inorganic tin in biological samples by hydride generation-atomic absorption spectrometry (HG-AAS). A sample is extracted with ethyl acetate after addition of HC1 and NaCl. The concentrated extract is passed through a silica gel column. The column is washed with ethanol, water, and 0.2N HC1 successively, and then inorganic tin is eluted with 2N HC1 and measured by HG-AAS. Recoveries from fish muscle spiked with 0.1 ng/g Sn4+ are 78.9 ± 4.2% (average ± standard deviation, n = 5). The detection limit is 0.01 jug/g as Sn.
Detection of Poultry and Pork in Cooked and Canned Meat Foods by Enzyme-Linked
Immunosorbent Assays
Authors: Berger Ronald G , Mageau Richard P , Schwab Bernard , Johnston Ralph W
Published: February 2020

Enzyme-linked immunosorbent assays (ELISA) are described for the detection of poultry and pork in cooked and canned muat foods. These assays are based on species-specific, polyclonal antibodies raised against heat-resistant antigens. The heat-resistant antigens were isolated from raw skeletal muscle tissue of pork and chicken and were found to be immunoreactive even after heating to 120°C for 15 min. The poultry ELISA could detect chicken or turkey at the 126 ppm level, and the pork ELISA could detect pork at the 250 ppm level. Samples of frankfurters, bolognas, pressed meats, canned baby foods, and canned spreads were prepared by simple aqueous extractions
Ion Abundance Criteria for Gas Chromatographic/Mass Spectrometric
Environmental Analysis
Authors: Donnelly J R , Sovocool G W , Mitchum R K
Published: February 2020

Mass and intensity calibration of gas chromatograph/mass spectrometer (GC/MS) responses is an important quality assurance issue for chemical analysis. Ion abundance calibration with decafluorotriphenylphosphine (DFTPP) was applied in 1975 to standardize quadrupole spectra to resemble the ion abundances that were obtainable from magnetic sector mass spectrometers. Modern <j uadrupole mass spectrometers provide significantly greater high-mass sensitivity than allowed under the 1975 study. Thus, those recommendations were reevaluated with 2 approaches. First, an interlaboratory study was conducted using 15 different gas chromatography/mass spectrometry (GC/MS) systems. Second, the U.S. Environmental I'rotection Agency Contract Laboratory Program (EPA-CLP) quality assurance data base was searched and over 6500 DFTPP tune results were plotted and evaluated. Based on these approaches, updated ion abundance criteria recommendations have been developed, which contemporary instruments can meet, and which meet data quality objectives regarding identification and quantitative analysis of analytes.
Liquid Chromatographic Determination of Cimetidine in Whole Blood and Plasma by Using
Short Polymeric Reverse Phase Column
Authors: Abu M Rustum , Hoffman Norman E
Published: February 2020

A rapid and simple reverse phase liquid chromatographic method for the separation and quantitation of the H2-receptor antagonist drug cimetidine in human whole blood and plasma is described. The method involves a single step organic extraction of the drug from alkalinized biological samples followed by a salting-out of the organic solvent by an appropriate salt. A short column packed with polymeric reverse phase particles was used with an isocratic elution of 20mM potassium phosphate (pH = 9.5) and acetonitrile (87.5 + 12.5). The cimetidine was monitored at 210 nm and 0.10-0.005 absorbance unit full scale (AUFS). The relative standard deviation I %) for analysis was reproducible within 1 day and that for day-to-day analysis was 5 (n = 8) or lower
Combined Extraction-Cleanup Column Chromatographic Procedure for Determination of
Dicofol in Avian Eggs
Authors: Krynitsky Alexander J , Stafford Charles J , Wiemeyer Stanley N
Published: February 2020

Dicofol in avian eggs was completely oxidized to dichlorobenzophenone (DCBP) when a hexane Soxhlet extraction procedure was used. This degradation did not occur with other avian tissues (muscle and liver). For this reason, a combined extraction-cleanup column chromatographic procedure, without added heat, was developed for the determination of dicofol in avian eggs. Homogenized subsamples of eggs were mixed with sodium sulfate, and the mixture was added as the top layer on a column prepacked with Florisil. The dicofol and other compounds of interest were then eluted with ethyl etherhexane. The extracts, relatively free from lipids, were quantitated on a gas chromatograph equipped with a 63Ni electron-capture detector and a methyl silicone capillary column. Recoveries from chicken eggs, fortified with dicofol and other DDT-related compounds, averaged 96%. Analysis of eggs of eastern screech-owls, fed a meat diet containing 10 ppm technical Kelthane, showed that both dicofol and DCBP were present. Results were confirmed by gas chromatography/ mass spectrometry. This method is rapid and reliable, involves a minimum of sample handling, and is well suited for high volume determination of dicofol in eggs and other avian tissues
Characterization of Benzyl Isothiocyanate and Phenyl Acetonitrile from Papayas by
Mass Spectrometry
Authors: Cairns Thomas , Siegmund Emil G , Stamp John J , Jacobs Richard M
Published: February 2020

Two unidentified analytical responses in a papaya extract were structurally determined by mass spectrometry to be benzyl isothiocyanate and phenyl acetonitrile. Both these compounds have previously been shown to result from degradation of benzylglucosinokte that occurs naturally in the seeds of the fruit. Characterization by mass spectrometry has now provided a convenient mechanism to detect both these degradation compounds in extracts resulting from routine pesticide residue analysis
Review of the Decontamination of Aflatoxins by Ammoniation: Current Status and Regulation
Authors: ParK Douglas L , Lee Louise S , Price Ralph L , Pohland Albert E
Published: February 2020

Ammoniation of corn, peanuts, cottonseed, and meals to alter the toxic and carcinogenic effects of aflatoxin contamination has been the subject of intense research effort by scientists in various government agencies and universities, both in the United States and abroad. Results of these studies have been well documented over the last 20 years. Engineers have devised workable systems of treatment of whole seeds, kernels, or meals; chemists have identified and characterized products formed from the reaction of aflatoxin B, with ammonia with and without a meal matrix; biochemists have studied the biological effects of these compounds in model systems; and nutritionists have studied animal responses to rations containing ammoniated or nonammoniated components. This review describes these studies. Results demonstrate overwhelming support for the efficacy and safety of ammoniation as a practical solution to aflatoxin detoxification in animal feeds.
Liquid Chromatographic Method for Determination of Citreoviridin in Corn and Rice
Authors: Stubblefield Robert D , Greer Judith I , Shotwell Odette L
Published: February 2020

Citreoviridin, a neurotoxic mycotoxin, has been found as a natural contaminant in corn left unharvested in the southeastern United States and in rice of several Asian countries, including Japan. A reliable analytical method for the quantitative determination of citreoviridin in corn and rice is described. Corn or rice is extracted with dichloromethane, and the extract is partially purified on silica and amino solid-phase extraction (SPE) columns. The extract is analyzed for citreoviridin by normal-phase liquid chromatography, using a mobile phase of ethyl acetate-hexane (75 + 25) at 1.5 mL/min and a fluorescence detector to measure the yellow fluorescence (388 nm excitation, 480 nm emission). With a 100 nL injection loop, the relationship between concentration and injection volume is linear for 20- 60 itL injections. Recoveries of citreoviridin added to yellow corn at 10-50 ng/g were 91.0-96.9%; recoveries from white corn (10-50 ng/g added) were 96.8-102.8%. Recoveries of 5000 ng/g added to white corn were 89.0%, indicating that heavily contaminated samples can be assayed by the method. Minimum detection limits were 10 ng for citreoviridin standard and 2 ng/g for citreoviridin added to corn. White rice fermented with Penicillium citreo-viride (1524 ppm) was mixed with and serially diluted with uncontaminated ground corn to obtain citreoviridin-contaminated corn (ca 25 ppb). When the samples were assayed by the method, a mean level of 24.4 ± 1.65 ppb (6.5% coefficient of variation) was obtained. Four fermented rice food samples and 3 commercial rice samples were investigated. Analyses of a fermented red rice and a fermented wild rice gave unsatisfactory results because impurities in partially purified extracts interfered with LC analysis. Extracts of most rice samples did not require cleanup by the SPE columns to remove interfering LC peaks.
β-Cyclodextrin Post-Column Fluorescence Enhancement of Aflatoxins for Reverse-Phase
Liquid Chromatographic Determination in Corn
Authors: Francis Octave J , Kirschenheuter Gary P , Ware George M , Carman Allen S , Kuan Shia S
Published: February 2020

β-Cyclodextrin enhances the fluorescence of aflatoxins B1 and G1 in aqueous systems. This effect was utilized in developing a unique reverse-phase liquid chromatographic (LC) method for determination of aflatoxins B1, B2, G1,and G2 (B1 detection limit 1 ppb), without preparing derivatives of B1 and G1. The aflatoxins are dissolved in methanol or the mobile phase for injection onto the LC system. Using a mobile phase of methanoI-β-cyclodextrin (1 + l), the aflatoxins are resolved on a C18 column. Fluorescence of the aflatoxins is enhanced by post-column introduction of an aqueous concentrated 0-cyclodextrin solution. All 4 aflatoxins elute within 10 min in the order G2, G1, B2, B1. Fluorescence responses for B1 and G1 standards were linear over the concentration range 0.5-10 ng, yielding correlation coefficients (r) of 0.9989 and 1.000, respectively. The average peak response ratio for G^B, for the mobile phase-enhancement solution described was 0.765 with a coefficient of variation (CV) of 0.98%. CVs were 6.2, 9.0, and 7.5% for multiple assays of aflatoxin B1 in 3 samples of naturally contaminated corn. For samples of corn spiked to a total B1 content of 8.3 ng/g, average B1 recovery was 90% (CV 11.7%)
Gas Chromatographic Determination of Formaldehyde in Maple Syrup as 2,4-Dinitrophenylhydrazone Derivative
Authors: Baraniak Zbigniew , Nagpal Daljit S , Neidert Eli
Published: February 2020

A procedure is presented for the quantitative extraction and determination of formaldehyde in maple sap and syrup. The method is based on the reaction between formaldehyde and 2,4-dinitrophenylhydrazine and determination of the derivative by gas chromatography. The procedure was used to evaluate formaldehyde in saps and syrups of paraformaldehyde implanted trees. Average recoveries were 101.5 ± 5.7%. The detection limit was 0.078 mg/kg
Normal-Phase Liquid Chromatographic Determination of Menadione in Animal Feeds
Authors: Laffi Roberto , Marchetti Silvia , Marchetti Mario
Published: February 2020

A simple method is presented for determination of menadione in vitamin premixes and feedstuffs by normal-phase liquid chromatography (LC). Vitamin K3 is extracted and converted to free menadione, which can be determined directly by LC analysis. Peak area or height is measured at 251 nm, and menadione is quantitated by comparison with the working standard. Menadione can be estimated with a detection limit of 2.5 ppm. Recoveries for premixes ranged from 97.3 to 98.3% and for feedstuffs from 93.7 to 96.8%. The method allows the assay of all commercial K3 compounds in pure or stabilized form and is applicable to a wide variety of feeds and premixes.
Comments on AOAC Dry Ash Method for Digestion of Mineral-Mix Feeds
Authors: Latimer George W , Ilger Wayne , Hinojosa Heron , Roth Marta
Published: February 2020

Phosphorus in feeds or mineral mixes containing monobasic calcium phosphate cannot be determined accurately if the sample is subjected to the dry ash procedure described in AOAC method 7.125-7.128. HCl-insoluble calcium metaphosphates are formed at the high temperature required for ashing.
Interference by Tin in AOAC Dry-Ash Voltammetric Method for Determination of Lead and
Cadmium in Canned Foods
Authors: Holak Walter , Specchio John J
Published: February 2020

When lead and cadmium were determined in samples of canned food by the AOAC anodic stripping voltammetric method, an interference was observed which was believed to be tin(IV). This interference could cause false positive results for lead and cadmium. The electroactivity of tin(IV) was suppressed by increasing the concentration of tartaric acid in the supporting electrolyte from 0.005M to 0.1M after mixing with an equal volume of sample solution.
Determination of Insoluble, Soluble, and Total Dietary Fiber in Foods and
Food Products: Interlaboratory Study
Authors: Prosky Leon , Asp Nils-Georg , Schweizer Thomas F , Devries Jonathan W , Furda Ivan
Published: February 2020

A collaborative study was conducted to determine the insoluble dietary fiber (IDF), soluble dietary fiber (SDF), and total dietary fiber (TDF) content of food and food products by using a combination of enzymatic and gravimetric procedures. The method was basically the same as that developed for TDF only, which was adopted official final action by AOAC, except for changing the concentration of buffer and base and substituting hydrochloric acid for phosphoric acid. These changes were made to improve the robustness of the method. Duplicate blind samples of soy isolate, white wheat flour, rye bread, potatoes, rice, corn bran, oats, Fabulous Fiber, wheat bran, and a high fiber cereal were analyzed by 13 collaborators. Dietary fiber values (IDF, SDF, and TDF) were calculated as the weight of residue minus the weight of protein and ash. The coefficients of variation (CVs) of both the independent TDF determination and the sum of IDF and SDF were better than 15 and 18%, respectively, with the exception of rice and soy isolate. These 2 foods, however, contained only about 1% TDF. The CVs of the IDF were equally good, except for Fabulous Fiber, for which filtration problems occurred. The CVs for the SDF were somewhat high, but these products had very low SDF content. There was excellent agreement between the TDF determined independently and the TDF determined by summing the IDF and SDF. The method for separate determination of IDF and SDF requires further study. The modifications (changes in concentration of buffer and base and the use of hydrochloric acid instead of phosphoric acid) to the official final action method for TDF have been adopted.
Selective Membrane Electrode Potentiometry and Spectrophotometry of a Photochemical
Reaction of Thioredazine Hydrochloride
Authors: Shoukry Adel F , Badawy Sayed S
Published: February 2020

A PVC membrane electrode of the coated wire type was prepared which is selective for thioredazine. It showed a Nernstian response over a thioredazine concentration range 6.3 x 10 «to 2.5 x 10_3M, at 25°C, and was selective, precise, and usable within the pH range 2.1-7.0. The standard electrode potentials, E°, were determined at different temperatures and used to calculate the isothermal temperature coefficient of the electrode. The photoreaction occurring in thioredazine solution exposed to daylight did not affect the electrode performance. This reaction was investigated kinetically to determine its rate constant and half-life at different temperatures.
Determination of Nitrogen Content in Milk by the Kjeldahl Method Using Copper Sulfate: Interlaboratory Study
Authors: Grappin R , Horwitz William
Published: February 2020

Copper sulfate was substituted for mercury as the catalyst in the International Dairy Federation (IDF) Standard 20A:1986 method for the determination of nitrogen content in milk. The substitution was supported by results obtained in an interlaboratory study by 24 laboratories in 12 countries. Each laboratory analyzed 12 test samples of milk as blind duplicates in a double split level design with high, medium, and low nitrogen concentrations. The method protocol requires the concurrent analyses of an ammonium salt solution and a tryptophan solution as internal quality control standards with a minimum nitrogen recovery between 99 and 100% for the former and at least 98% for the latter. The repeatability and reproducibility relative standard deviations are 0.5 and 1%, respectively, for the range 0.35-0.70 g N/100 g. The performance of the laboratories that did not meet the required quality control specifications was clearly poorer than that of those that did meet the specifications.
Determination of Sulfite in Foods by Headspace Liquid Chromatography
Authors: Lawrence James F , Chadha Rajinder K
Published: February 2020

Sulfite was determined in a variety of foods by liquid chromatography (LC) after the samples were mixed with a solution containing mannitol, FeS04, and Na2HP04, adjusted to pH 11, and left to stand for 15 min at room temperature. An aliquot of the mixture was placed in a headspace vial and mixed with 50% H3P04. After 15 min, a portion of the headspace was removed with a syringe containing LC mobile phase without acetonitrile. The syringe was shaken and an aliquot of the solution was analyzed on an anion exchange column with a mobile phase of 0.03M methane sulfonate (pH 10.8) containing 5% acetonitrile. Sulfite was detected amperometrically (glassy carbon electrode) at +0.7 V. The method was successfully compared to the FDA-modified Monier-Williams procedure for a variety of foods. Minimum detectable levels were about 1 ng/g, based on a 15 g sample
Fluorometric Determination of Benzylideneacetone in Fragrance Products by Liquid Chromatography with Post-Column Derivatization
Authors: Yates Ronald L , Wenninger John A
Published: February 2020

A method is described for the liquid chromatographic (LC)-fluorometric determination of benzylideneacetone in fragrance products. Benzylideneacetone is first separated from other fragrance ingredients by LC and then reacted post-column with a methanolic solution of isonicotinic acid hydrazide and aluminum nitrate. The reactants are maintained at 65°C for about 1.5 min to quantitatively form the fluorescent isonicotinoyl hydrazone derivative of benzylideneacetone. The aluminum ion forms a complex with the hydrazone to enhance the fluorescence of the derivative. The amount of benzylideneacetone is determined by measuring the intensity of the fluorescence emitted by the hydrazone derivative and comparing that value with those obtained for derivatized standards. Recovery studies were conducted by spiking commercial fragrances with benzylideneacetone at concentrations of 0.01,0.05, and 0.1% (w/v). Recoveries ranged from 98 to 104% with a mean recovery of 100.2% and a standard deviation of 2.4%.
Visual Immunoassay for Detection of Salmonella in Foods: Collaborative Study
Authors: Flowers Russell S , Klatt Mary Joan , Keelan Susan L
Published: February 2020

A collaborative study was performed in 13 laboratories to validate a visual enzyme immunoassay (EIA) procedure, TECRA®, for rapid detection of Salmonella in foods. The EIA method was compared with the standard culture procedure for detection of Salmonella in 6 food types: ground black pepper, soy flour, dried whole eggs, milk chocolate, nonfat dry milk, and raw deboned turkey. Uninoculated and inoculated samples were included in each food group analyzed. There was no significant difference in the productivity of the EIA and culture procedures at the 5% level for any of the 6 foods. The enzyme immunoassay screening method has been approved interim official first action.
Gas Chromatographic/Mass Spectrometric Confirmation of Identity of Coprostanol in Mercenaria mercenaria (Bivalvia) Taken from Sewage-Polluted Water
Authors: Matusik Jean E , Hoskin George P , Sphon James A
Published: February 2020

Coprostanol is a major fecal sterol in humans and may, therefore, be a good indicator of sewage-polluted waters. Some types of edible seafood, such as clams, that live in these waters may be contaminated with coprostanol. Coprostanol from clam tissue extracts had been previously quantitated by gas chromatography (GC). In the present work, capillary column GC was used to separate coprostanol, and electron ionization mass spectrometry was used to confirm its identity. Confirmation of identity of coprostanol at the 75 ng level was obtained by comparing the spectrum of the authentic standard with spectra of the clam tissue extract obtained under the same instrumental conditions. Various other compounds can be eliminated as potential interferences by virtue of either their different GC retention times or their spectra.
Enhanced Surveillance of Foodborne Mycotoxins by Immunochemical Assay
Authors: Pestka James J
Published: February 2020

Mycotoxins are a chemically diverse group of fungal secondary metabolites with a wide range of toxic effects. Conventional thin-layer and instrumental methods of mycotoxin analysis are time-consuming and make routine safety and quality control screening of these compounds in agricultural commodities difficult. As an alternative, specific polyclonal and monoclonal antibodies have been raised against mycotoxin-protein conjugates and used in sensitive radioimmunoassays (RIAs) and enzyme-linked immunosorbent assays (ELISAs). One of the simplest ELISA approaches involves competition for a solid-phase antibody between a mycotoxin-enzyme conjugate and an unconjugated mycotoxin in the sample extract. ELISAs have been developed for aflatoxins B, and M„ zearalenone, T-2 toxin, and deoxynivalenol, which are highly specific, rapid (10 min), easily adaptable for analyzing large numbers of samples, and directly applicable to assaying methanol-water extracts of a wide range of foods. Several commercial mycotoxin ELISAs using this approach (most typically for aflatoxin B,) are currently being marketed. Since ELISAs will be used in large part by personnel with limited technical expertise, individual kits must be critically evaluated by analytical chemists for suggested sampling procedures, efficiency of extraction, crossreactivity, mycotoxin recovery, assay reproducibility, and product shelf-life prior to routine use in food safety and quality control screening
Electrophoretic Methods for Screening for Antibiotics in Animal Feeds
Authors: Salvatore Michael J , Katz Stanley E
Published: February 2020

A new system for screening antibiotics in animal feeds involves washing antibiotic-containing animal feeds with a series of organic solvents to eliminate interferences and partially separate the antibiotics. Antibiotics are then determined by using paper electrophoresis and thin-layer bioautography. This approach enables the separation and qualitative identification of 17 antibiotics currently used in animal feeds and provides the ability to detect low-level cross-contamination
Nicotine Analysis of Commercial Tobacco Products
Authors: Gottscho Alfred M , Lin Jeen-Lee , Duck William N , Losty Thomas A
Published: February 2020

The use of AOAC standard methods for the determination of nicotine in commercial tobacco products is shown to be inappropriate. The methods do not provide for suitable sample preparation of these products for the analysis and, in addition, they yield high results. Evidence is presented that the nicotine or total alkaloids measured includes artifact nicotine. The distillation method was developed at a time when the complex alkaloid chemistry of tobacco was unknown, and does not take into consideration the possible contribution of substances in tobacco capable of contributing falsely to the result. The Cundiff-Markunas method, developed more recently, also fails to account for this effect—probably because it was designed to produce results matching those of the distillation method. Replacement of the standard methods is proposed and some alternative procedures are suggested
Dimetridazole Residues in Pork Tissue. I. Assay by Liquid Chromatography with
Electrochemical Detector
Authors: Carignan Germain , Skakum William , Sved Stephen
Published: February 2020

A liquid chromatographic (LC) method with electrochemical detection in the reductive mode was developed for the quantitative determination of dimetridazole (DMZ) and its major metabolite (HMMNI) at residue levels in pork tissue. For blood plasma, a sample is precipitated with 2 volumes of acetonitrile and centrifuged, and a diluted aliquot of the supernatant liquid is chromatographed. For muscle, a 10 g sample is extracted 3 times with dichloromethane. After evaporation of the combined extracts, the residue is redissolved in a mixture of hexane and mobile phase (0.3% TEA in 0.6M ammonium acetate pH 5.0 and acetonitrile, 85 + 15) and centrifuged, and an aliquot of the lower phase is chromatographed. Chromatography is accomplished using valve switching with 2 liquid circuits, employing the same mobile phase for both. The sample is deaerated by sparging with helium under slight positive pressure to prevent rediffusion of the oxygen. The sample is first loaded into a deoxygenator and the flow is stopped for complete deoxygenation. The flow is then resumed to transfer the sample into the first, low back-pressure column (ODS, 10 μm, 4.6 x 200 mm). Switching the valve at this point removes the deoxygenator from the circuit and connects the first column to a second one (ODS, 5 μm, 4.6 x 150 mm) in tandem. After the effluent is passed through a second deoxygenator to reduce the residual oxygen in the mobile phase, it is monitored by an electrochemical detector with a screened wall jet cell and a gold mercury electrode, set at —1.2 V. The response is linear, in the ranges studied: 100-1000 pg for DMZ and 200-1000 pg for HMMNI. Mean recoveries for the extraction method are 56 and 70% for DMZ and HMMNI, respectively, using spiked meat and plasma samples at 0.26-2 ppb. Essentially 100% recoveries are obtained with spiked (10 ppb) plasma, using the acetonitrile precipitation
Determination of Acid-Detergent Fiber and Crude Protein in Forages by Near-Infrared
Reflectance Spectroscopy: Collaborative Study
Authors: Barton II Franklin E , Windham William R
Published: February 2020

A Collaborative Study Was Conducted To Determine The Standard Error Of Difference Among Laboratories For Near-Infrared Reflectance Spectroscopic (Nirs) Determination Of Acid-Detergent Fiber (Adf) And Crude Protein In Forages. The 6 Participating Laboratories Were Members Of The Usda/Ars National Near-Infrared Reflectance Spectroscopy Forage Research Project. The Nirs Calibration Equations Were Developed In The Associate Referee's Laboratory For Crude Protein And Adf And Were Transferred To The Instrument In Each Of The Other Collaborating Laboratories. The Calibration Set Included Over 650 Diverse Forage Samples With Crude Protein And Adf Calibration Data; The Validation Set Included 94 Samples Of Bermudagrass. Amonglaboratory Reproducibility For The Nirs Method, Calculated As The Relative Standard Deviation For Reproducibility (Rsdr), Was 1.14% For Adf And 0.42% For Crude Protein. The Variance Component For Among-Laboratory Variation (Coefficient Of Variation) Was 2.54% For Adf And 2.89% For Crude Protein. These Results Confirm That It Is Possible To Calibrate, Validate, And Transfer (Nirs) Equations And Data Among Laboratories For The Accurate Determination Of Adf And Crude Protein, And Thereby Demonstrate That Nirs Can Be Used As A Standard Method For The Analysis Of Forages. The Method Has Been Adopted Official First Action
Spectrophotometric Determination of Cyclamate in Soft Drinks and Desserts:
Complementary Collaborative Study
Authors: SJÖBERG Anna-Maija K
Published: February 2020

Fifteen official food control laboratories participated in a collaborative study of a spectrophotometric method to determine cyclamate in a soft drink and a dessert at concentrations of 90-311 mg/L and 202-526 mg/kg, respectively, with blind duplicates and a blank. Average recovery from the soft drink was 97.5%, and from the dessert, 98.6%. Reproducibility relative standard deviations were 4.7-6.5% and 6.9-8.5%, respectively. The outlier percentage was 5.5%. This study complements an earlier work by leading Nordic food laboratories and was designed according to the latest recommendations. The results of this study were compared with those of the earlier collaborative study and with general collaborative results obtained by AOAC.
Investigations on N-Nitrosopyrrolidine in Dry-Cured Bacon
Authors: Fiddler Walter , Pensabene John W , Gates Robert A , Foster Judith M , Smith Wertice J
Published: February 2020

Dry-cured or "country-style" bacon is a low volume specialty product typically made by small producers whose production practices vary widely. These practices include the direct application of dry-cure formulations containing varying concentrations of salt, sugar, flavoring agents, sodium nitrite, and sometimes sodium nitrate, and the use of lengthy curing and processing times. Because of the possibility of generating higher levels of N-nitrosopyrrolidine (NPYR) after frying in this product type compared with pump-cured bacon, an investigation was carried out on dry-cured bacon obtained from cooperating state or federally inspected establishments. Three different samples from each of the 16 plants were analyzed. Only one sample from each of 2 different producers exceeded the Food Safety and Inspection Service (FSIS) action level of 17 ppb NPYR, indicating that the majority of samples tested were in compliance. A significant correlation (P < 0.01) was found between residual NaN02 prior to frying and NPYR after frying. The elimination of added nitrate in the dry-cure formulations is recommended.
Application of Near Infrared Reflectance Spectroscopy to Determination of Fat in Cheddar Cheese
Authors: Wehling Randy L , Pierce Michelle M
Published: February 2020

Near infrared reflectance (NIR) "spectroscopy was used to determine the fat content of Cheddar cheese. Through multiple linear regression, calibrations were developed for use with a commercial filter monochromator instrument. A 6-wavelength calibration, using 1734 nm as the primary indicator wavelength, was found to perform satisfactorily. Averaging readings from duplicate sample repacks reduced the standard error of performance (SEP) compared with the use of single readings. For a validation set of 23 samples, the correlation coefficient squared (r2) between the NIR and Roese-Gottlieb methods was 0.92, with an SEP of 0.44%. Both sample temperature and age of the cheese influenced the NIR response.
Liquid Chromatographic Determination of Carminic Acid in Yogurt
Authors: Jalón Mercedes , Peńa Majesús , Rivas Julián C
Published: February 2020

A reverse-phase liquid chromatographic method is described for the determination of carminic acid in yogurt. A C18 column is used with acetonitrile-1.19M formic acid (19 + 81) as mobile phase and diode array detection. Sample preparation includes deproteinization with papain and purification in a polyamide column. The relative standard deviation for repeated determinations of carminic acid in a commercial strawberry-flavored yogurt was 3.0%. Recoveries of carminic acid added to a natural-flavored yogurt ranged from 87.2 to 95.3% with a mean of 90.2%. The method permits measurement of amounts as low as 0.10 mg/kg.
Determination of Maduramicin by Liquid Chromatography with Atomic Absorption Spectrometric Detection
Authors: Johnson Nelson A
Published: February 2020

A liquid chromatograph was interfaced to an atomic absorption spectrometer for the detection and quantitation of maduramicin in feed matrixes at the 1-8 ppm level. Ionophores in general form strong 1:1 products with various metal cations, yielding complexes that are insoluble in water but very soluble in organic solvents. Maduramicin, a carboxylic, polyalcohol, polyether antibiotic, is labeled with the sodium cation and analyzed by atomic absorption spectroscopy (AAS). The lower limit of detection is approximately 100-200 ng maduramicin sodium salt. Feeds containing 1-8 ppm maduramicin are extracted with acetone, the extract is passed through an alumina column, the column is eluted with acetonitrile-water (90 + 10), and the eluate is analyzed for maduramicin by liquid chromatography- AAS after concentration and conversion of maduramicin to the sodium salt. Recoveries of maduramicin averaged 89.5%. Liquid chromatography with AAS detection has been shown to be a sensitive and highly specific technique for the determination of ionophores in general and maduramicin in particular.
Liquid Chromatographic Methods for Vitamins A and D in Multivitamin-Mineral Formulations
Authors: Beaulieu Normand , Curran Norman M , Gagné Charles , Gravelle Micheline , Lovering Edward G
Published: February 2020

Liquid chromatographic screening procedures have been developed for the estimation of vitamins A and D in multivitamin-mineral tablet, capsule, gelatin capsule, and syrup formulations. The procedure can be used for measuring vitamin A present as either retinyl acetate or retinyl palmitate, and also for measuring the contribution to total vitamin A activity from 13-cis retinyl esters. The retinyl esters and their isomers are resolved from each other and their oxidation products. Ergocalciferol and cholecalciferol are not resolved from each other but they are resolved from other vitamin D isomers and from vitamins A, E, and K and their degradation products. Both assays use a 3 μm amino column, with a mobile phase of hexane for vitamin A and 1% isopropanol in hexane for vitamin D. The precision of replicate injections for vitamins A and D is better than 1% and the recovery from spiked syrups is better than 98%. The coefficient of variation for both assay methods is about 5%. Twenty formulations were analyzed for vitamin A and 24 were analyzed for vitamin D.
Determination of Arsenic in Beer by Dry Ashing, Hydride Generation Atomic Absorption Spectroscopy
Authors: Cervera Ma Luisa , Navarro Ascensio , Montoro Rosa , Catala Ramon , Ybańez Nieves
Published: February 2020

A method has been developed for determination of arsenic in beer. Organic matter is destroyed by the dry-ashing technique, the ash is dissolved in HC1, and hydrides of arsenic are generated by addition of sodium borohydride prior to atomization in a flame-heated quartz cell and atomic absorption spectroscopy measurement. The analytical features of the method are detection limit 0.1 ng/g beer, precision 8%, and recovery 97 ± 7%. The arsenic contents of different brands from Spain and other European countries were analyzed. In all samples, the arsenic levels found were well below maximum levels allowed in Spanish legislation (100 ng/g). The quantities of arsenic in Spanish beers do not differ from those found in foreign beers. No differences were found between bottled and canned beers, and no correlation exists between metal content and original specific gravity of the beers.
Enzyme-Linked Immunosorbent Assay for Screening Aflatoxin B1 in Cottonseed Products and Mixed Feed: Collaborative Study
Authors: Park Douglas L , Miller Brinton M , Hart L Patrick , Yang George , McVey James , Page Samuel W , Pestka James , Brown Lois H
Published: February 2020

A joint AOAC/IUPAC (International Union of Pure and Applied Chemistry) interlaboratory study of an enzyme-linked immunosorbent screening assay (ELISA) for aflatoxins was conducted in laboratories in Canada, France, Japan, South Africa, Switzerland, The Netherlands, Tunisia, and the United States. Twenty-eight samples of raw and roasted peanuts, corn, whole cottonseed, cottonseed meal, ammoniated cottonseed meal, and poultry feed containing various quantities of natural aflatoxins and supplemented when appropriate with aflatoxin B1 were distributed to participating laboratories for testing. The assay is based on conjugation of pure aflatoxin B1 to an enzyme and the competition between this conjugate and (free) aflatoxins in the product for aflatoxin-specific antibodies coated onto microtiter well walls. After a wash step to remove all unbound aflatoxins, a substrate, added to each well, is catalyzed from a colorless to a green solution by any bound enzyme-conjugated aflatoxin Bf present. The intensity of the color decreases as the amount of free aflatoxin B1 in the product increases. Overall correlation was good between ELISA and thin-layer chromatographic (TLC) results for cottonseed products and mixed feed. Variable results were reported for corn and peanut product samples. Although some positive samples (> 15 ng/g) of cottonseed products and mixed feed were reported to contain < 15 ng/g by visual determination, a review of data for absorbance measurements showed that the contamination level was close to the ≥ 15 ng/g standard and would not have been reported as negative under routine screening. Variation in ELISA results may have been due to several factors such as: lack of homogeneity of the aflatoxin contamination in the samples (prestudy TLC analysis samples were collected randomly from a pool of subsamples), interferences that resulted from incomplete removal of hexane during the filtration step, and antibody strips at or past their expiration date. The ELISA method has been adopted official first action as a screening method to determine the presence or absence of aflatoxin B1 at a concentration of ≥ 15 ng/g in cottonseed products and mixed feed.
Determination of Acidic Herbicides and Related Compounds in Water and Soil by Capillary Gas Chromatography Using a Nitrogen-Phosphorus Detector
Authors: Ahmed Abdul W , Mallet Victorin N , Bertrand Michel J
Published: February 2020

Methods are described for the determination of acidic herbicides and related compounds in water and soil. Eight acidic herbicides and related compounds were extracted from water using either dichloromethane or an XAD-2 resin column. The acidic moieties were derivatized with 2-cyanoethyldimethyl(diethyl)aminosilane. The derivatized compounds were separated using capillary gas chromatography and quantitated using a nitrogen-phosphorus detector. Extraction from water using dichloromethane or an XAD-2 resin column resulted in recoveries > 90% at 0.1 ppb with an average coefficient of variation (CV) of 6%. In soils extracted with aqueous acetonitrileacetic acid and partitioned into dichloromethane, recoveries at 500 ppb were > 75% with an average CV of 3.3%. The methods are rapid and there are few interferences.
Spectrofluorometric Determination of Histamine in Wines and Other Alcoholic Beverages
Authors: Vidal-Carou M C , Izquierdo-Pulido M L , Mariné-Font A
Published: February 2020

The spectrofluorometric determination of histamine in wines, other alcoholic beverages, and vinegars is described. Histamine is extracted with n-butanol, transferred to hydrochloric acid, and subjected to a condensation reaction with o-phthalaldehyde (OPT). The method was tested for sensitivity (0.03 ppm limit of detection and 0.08 ppm limit of determination), precision (6.4% CV for a content of 1.25 ppm and 19.5% CV for a content of 0.25 ppm), accuracy (97.1%), recovery (90.6-96.9%), and lack of interference by histidine. The method can be applied to wine, must, beer, champagne, cider, vermouth, and vinegar with satisfactory results.
Direct Competitive Enzyme-Linked Immunosorbent Assay for Sulfamethazine Residues in Milk
Authors: Dixon-Holland Deborah E , Katz Stanley E
Published: February 2020

A direct competitive enzyme-linked immunosorbent assay (ELISA) is described for the detection and estimation of sulfamethazine residues in milk. Samples are cleaned up rapidly by acidifying and centrifuging the milk, adjusting the supernatant liquid to pH 7.0, and centrifuging again. The supernate is then assayed using set points to estimate sulfamethazine levels in the sample in the range of 1 ppb to 1 ppm. Multiple samples of milk can be screened in 1.5-2 h by this ELISA method.
Optimized Monier-Williams Method for Determination of Sulfites in Foods: Collaborative Study
Authors: Hillery Barbara R , Elkins Edgar R , Warner Charles R , Daniels Dan , Fazio Thomas
Published: February 2020

A collaborative study was conducted of the Food and Drug Administration (FDA)-optimized Monier-Williams method for determining sulfites in foods. Twenty-one industry and government laboratories participated in the study, which was jointly sponsored by the National Food Processors Association and FDA. Familiarization samples were shipped to each collaborator. Collaborators were permitted to proceed to the main study only after they demonstrated ability to perform the method to ensure that the study tested the performance of the method itself and not that of the individual laboratories. The study design involved 3 food matrixes (hominy, fruit juice, and protein [seafood]). Each matrix was prepared at 3 sulfite levels—the regulatory level, half the regulatory level, twice the regulatory level— and as a blank. All test samples were analyzed as blind duplicates, which gave each collaborator a total of 24 test portions. Collaborative recoveries gave a reproducibility (among-laboratories) coefficient of variation that ranged from 15.5 to 26.6% for sulfite determined as S02 by weight in the 3 foods at the 10 ppm level. The optimized Monier-Williams method has been approved interim official first action to replace the AOAC modified Monier-Williams method, 20.123-20.125.