bluuebunny/crossref_metadata_2025 huggingface dataset:
Confirmation of Identities of Propylene and Ethylene Glycols in Anchovies by Tandem Mass Spectrometry
Authors: Matusik Jean E , Eilers Paul P , Waldron Ellen M , Conrad Steve M , Sphon James A
Published: February 2020

A gas chromatographic/tandem mass spectrometric (GC/MS/MS) method has been developed for confirming the identity of propylene and ethylene glycols added to bait fish for preservation. Bait fish are occasionally illegally diverted to human food use. The bait fish were extracted with methanol, the extract was centrifuged and filtered, and the filtrate was concentrated 10-fold and then analyzed by GC/MS/MS. The glycols were separated chromatographically without derivatization or preliminary cleanup. Isobutane positive ion chemical ionization was used to generate the protonated molecular ion species of each glycol. Product-ion MS/MS experiments were performed to obtain spectra to confirm the identities of propylene and ethylene glycols. The identities of these 2 compounds in anchovy extracts were successfully confirmed by this approach.
Determination of Streptomycin and Dihydrostreptomycin in Animal Tissue by On-Line Sample Enrichment Liquid Chromatography
Authors: Gerhardt Geoff C , Salisbury Craig D C , MacNeil James D
Published: February 2020

A method for the determination of streptomycin and dihydrostreptomycin in pork and bovine muscle and kidney was developed. Dilute perchloric acid solution is used to precipitate proteins and extract the analytes from the tissue. The extract is loaded onto a cation-exchange, solid-phase extraction column, and the drugs are eluted with pH 8 phosphate buffer. The eluant is chromatographed by using an on-line column enrichment liquid chromatographic system with postcolumn derivatiza-tion using 1,2-naphthoquinone-4-sulfonic acid and detection by fluorescence. The recoveries were 61.1% (coefficient of variation [CV], 7.3%) for streptomycin and 55.3% (CV, 8.2%) for dihydrostreptomycin. The detection limits were 10 ppb for streptomycin and 20 ppb for dihydrostreptomycin.
Iron Milk Medium Method for Recovering Clostridium perfringens from Shellfish: Collaborative Study
Authors: Abeyta Carlos , Wetherington June H
Published: February 2020

Eleven laboratories participated in a collaborative study analyzing shellfish (oysters, Crassostrea gigas) for the detection and enumeration of Clostridium perfringens by the iron milk medium (IMM) method. The IMM method was compared to AOAC Official Method 976.30. Shellfish were artificially inoculated with C. perfringens cells (vegetative and spores) at low (1 × 103 colony forming units [cfu]/g), medium (1 × 104 cfu/g), and high (1 × 106 cfu/g) levels. Negative controls (zero level) were analyzed by each laboratory. C. perfringens FD-1, the strain involved in a foodborne illness, was used. Blind duplicates of each inoculum level were analyzed, giving a total of 16 samples per laboratory. The selectivity of IMM relies solely on the rapid growth of C. perfringens at 45°C indicated by stormy fermentation reaction within 18 h. C. perfringens is detected and enumerated using the most probable number technique. A statistical evaluation of the data found no significant differences between the estimates from the 2 methods. The IMM method for detection of C. perfringens from shellfish has been adopted first action by AOAC INTERNATIONAL.
Visual Screening with Enzyme Immunoassay for Staphylococcal Enterotoxins in Foods: Collaborative Study
Authors: Bennett Reginald W , McClure Foster
Published: February 2020

Selected foods containing 4–10 ng each of a mixture of Staphylococcus aureus enterotoxin serotypes A–E were tested by 15 collaborators. An enzyme-linked immunosorbent assay (EIA) was used with polyvalent antisera to these serotypes in a polyclonal antibody double “sandwich” configuration. Controls were free of toxin. Foods (25 g test samples) were homogenized with Tris (0.25M, pH 8.0) and centrifuged. The food extract was filtered through cotton and mixed with sample additive. For the EIA, 200 μL aliquots of the treated extracts were added to previously washed microtiter wells coated with antibody to staphylococcal enterotoxin serotypes A–E. Wells were washed and treated with the polyvalent antisera (A–E)-enzyme conjugate, and then washed again. Substrate was added, and wells were incubated. After incubation, stop solution was added. Results were determined visually and by measuring absorbance using a microtiter plate reader. In foods containing enterotoxin, bluish-green color was developed (positive result). Test solutions with absorbances >0.200 were considered positive; those with absorbances ≤0.200 were negative. The method is sensitive and specific, and allows the rapid assay of staphylococcal enterotoxins in foods without differentiating their serotypes. The method has been adopted first action by AOAC INTERNATIONAL.
Identification of Hairs of Three Asian Commensal Mammals: Suncus murinus, Bandicota bengalensis, and Rattus exulans
Authors: Bryce John R
Published: February 2020

Hairs of 3 major Asian commensal mammals, Suncus murinus (L.), Bandicota bengalensis (Gray and Hardwicke), and Rattus exulans (Peale), were studied, identified, and compared with those of better-known commensal species to provide an overview of their hair morphologies. Techniques were developed for authentic hair specimen collection and rapid slide mounting to aid in the timely analysis of food products. The study showed that hairs of B. bengalensis and R. exulans are easily identified to the regulatory category of “rat or mouse hair,” whereas identification of S. murinus contaminant hairs is possible to the species level.
PAH RIS® Soil Test—A Rapid, On-Site Screening Test for Polynuclear Aromatic Hydrocarbons in Soil
Authors: McDonald Patricia P , Almond Richard E , Mapes James P , Friedman Stephen B
Published: February 2020

Polynuclear aromatic hydrocarbons (PAHs) are chemicals of concern when they contaminate the environment. Current detection methods (gas chromatography and liquid chromatography) are laborious, time consuming, and expensive. As an alternative, we developed a competitive enzyme-linked immunosorbent assay kit that can be used on site for the detection of PAHs at 1 ppm in soil. The immunoassay kit includes all the components necessary to conduct the analysis in the field. The test consists of 3 major steps: (1) sample treatment; (2) immunoassay, in which the target compound is bound by a specific antibody followed by the development of an indicator color; and (3) interpretation of results. A sample that develops less color than the standard is interpreted as positive (soil sample contaminated with PAHs at ≥1 ppm). Validation studies demonstrated that the assay is sensitive and specific. The assay detects PAH contamination in soil at 1 ppm or greater and specifically detects the 3- and 4-ringed aromatics and most of the 5-and 6-ringed aromatics. PAH-free soil samples gave negative results in the assay at a confidence level of >95%. Matrix effects, interperson, and interlot variations were minimal. The test requires <25 min to complete. The test kit is field compatible and provides a cost effective method for screening soils at risk for PAH contamination.
Cold-Vapor Generation for Inductively Coupled Argon Plasma/Atomic Emission Spectrometric Analysis. Part 3. Mercury
Authors: Anderson Kim A , Isaacs Brandon , Tracy Mark , Möller Gregory
Published: February 2020

A method is presented for the determination of total mercury in environmental samples by inductively coupled argon plasma/atomic emission spectroscopy (ICP/AES) using cold-vapor generation. A 1.0 g or 10 mL test portion is digested 6–12 h in a 16 × 150 mm, 10 mL volumetric test tube at room temperature and is subsequently digested on a programmed heating block at 95°C with trace-metal grade nitric acid. The digested samples are next treated with potassium permanganate and heated between 70 and 95°C; thereafter, oxalic acid is added to reach the final endpoint. The mercury(II) is reduced by sodium borohydride in a simplified continuous manifold. A standard pneumatic nebulizer effects the gas–liquid separation of mercury. Mercury is quantitated by ICP/AES at 194.232 nm. The instrument detection limit for the method is 0.2 μg/L. Water samples are analyzed directly. The detection limit is below the current National Primary Drinking Water Standard Maximum Concentration Limit of 2 μg/L for mercury. For a 10:1 dilution of a nominal 1.0 g solid test portion, the detection limit is 2.0 μg/L. This concentration is also less than the regulatory limit of 200 μg/L for the U.S. Environmental Protection Agency’s Toxicity Characteristic Leaching Procedure. The quantitation is linear up to 300 μg/kg. The method demonstrated statistical control for samples of biological and environmental interest.
Fumonisin Production by Fusanum Species on Solid Substrates
Authors: Nelson Paul E , Juba Jean H , Ross P Frank , Rice Larry G
Published: February 2020

Fumonisins were produced by strains of Fusarium moniliforme and F. proliferatum on a medium consisting of 500 g yellow corn kernels and 500 mL distilled water added to a 30.5 × 61 cm autoclavable polyethylene bag. The corn was inoculated by drawing a suspension from a lyophilized culture into a sterile 5 mL syringe fitted with a 19 gauge needle and injecting 1 mL through the side of each polyethylene culture bag. Bags of inoculated com were incubated in the dark at 20° to 22°C for 4 weeks. Seven to 8 days after inoculation, holes were punched near the tops of the bags to promote aeration. After a 4 week incubation, cultures were soaked in chloroform–acetone (50 + 50, v/v) in 4 L flasks overnight to kill fungus and to remove water. Next, the culture media was filtered through 2 mm nylon mesh screens and air dried from 24 to 48 h. Fumonisin concentrations were determined by liquid chromatography/o-phthalaldialdehyde fluorescence. Confirmation was by gas chromatography/mass spectrometry. We observed that the 3 most important factors in the production of fumonisins in bulk corn cultures were temperature control, moisture, and aeration. Extraction by acetonitrile–water (50 + 50, v/v) for 30 min produced the highest yields of fumonisins. Measurable concentrations were reduced by as much as 50% when culture material was heated at 50°C overnight. Fusarium moniliforme strains consistently produced fumonisin B1 as the major component, but some strains of F. proliferatum produced fumonisin B2 and/or fumonisin B3 at higher concentrations than fumonisin B1. Results were calculated on the basis of dried culture material.
Stability and Problems in Recovery of Fumonisins Added to Corn-Based Foods
Authors: Scott Peter M , Lawrence Guillaume A
Published: February 2020

Because the natural occurrence of fumonisins is so far known almost exclusively in corn, we have limited our investigations on their stability to corn-based foods. In these studies, distinction must be made between real losses, binding, and any matrix-related method problems. Fumonisins B1 (FB1) and B2 (FB2) were about 40% recovered when heated in corn meal at 190°C, about 20–30% recovered when heated in moist corn meal at 190°C, and completely unstable in corn meal at 220°C. Average recoveries of FB1 and FB2 added to blank heated matrixes were 69–107% in control experiments. Baking corn meal muffins spiked with 2.5 μg FB1 and FB2/g corn meal at 220°C also resulted in losses of fumonisins. Little or no fumonisins were recovered from corn bran flour when methanol–water (3 + 1) was used as extraction solvent. However, when methanol-borate buffer (pH 9.2) (3 + 1) was used, recoveries averaged 91 ± 17 and 84 ± 9%, respectively, for FB1 and FB2; and natural contamination of the corn bran flour with FB1 and FB2 at levels of 1.9 and 0.95 μg/g, respectively, was revealed. Comparable recoveries were observed for 1 brand of a corn bran breakfast cereal, but the binding effect was not seen with a second brand, for which methanol-water (3 + 1) alone was a good extraction solvent. Recoveries of FB1 and FB2 from a mixed cereal for babies were only about 50% with either extraction solvent mixture. Additives present in the mixed cereal—calcium carbonate, dibasic calcium phosphate, and reduced iron (iron filings)—did not affect recoveries of FB1 and FB2 when added to ground corn or corn flakes, although hydrated ferrous sulfate did.
Determination of Zinc in Serum, Blood, and Ultrafiltrate Fluid from Patients on Hemofiltration by Graphite Furnace/Atomic Absorption Spectroscopy or Flow Injection Analysis/Atomic Absorption Spectroscopy
Authors: De Blas Oroncio Jimenez , Rodriguez Ramon Seisdedos , Mendez Jesus Hernandez , Sanchez Tomero Jose Antonio , Gomez B De Leon , Gonzalez Secundino Vicente
Published: February 2020

Two methods were optimized for the determination of zinc in samples of blood, serum, and ultrafiltrate fluid from patients with chronic renal impairment undergoing hemofiltration. In the first procedure, after acid digestion of the samples, Zn in blood and serum is determined by a system coupled to flow injection analysis and atomic absorption spectros-copy. The method is rapid, automated, simple, needs small amounts of sample, and has acceptable analytical characteristics. The analytical characteristics obtained were as follows: determination range of method, 0.05-2.0 ppm of Zn; precision as coefficient of variation (CV), 5.3%; recovery, 95-105%; and detection limit (DL), 0.02 ppm. The second method is optimized for ultrafiltrate fluid because the sensitivity of the first procedure is not suitable for the levels of Zn (ppb or ng/mL) in these samples. The technique chosen was atomic absorption spectroscopy with electrothermal atomization in a graphite furnace. The analytical characteristics obtained were as follows: determination range of method, 0.3-2.0 ppb Zn; CV, 5.7%; recovery, 93-107%; and DL, 0.12 ppb. The methods were used to determine zinc in samples of blood, serum, and ultrafiltrate fluid from 5 patients with chronic renal impairment undergoing hemofiltration to discover whether there were significant differences in the zinc contents of blood, serum, and ultrafiltrate fluid after the hemofiltration process. An analysis of variance of the experimental data obtained from a randomly selected group of 5 patients showed that zinc concentrations in the ultrafiltrate fluid, venous blood, and venous serum do not vary during hemofiltration (p < 0.05), whereas in arterial blood and serum, the time factor has a significant effect.
Packed-Column Gas Chromatographic Method for the Simultaneous Determination of 10 Pyrethroid Insecticide Residues in Fruits, Vegetables, and Grains
Authors: Pang Guo-Fang , Fan Chun-Lin , Chao Yan-Zhong , Zhao Tee-Sheng
Published: February 2020

A simple, rapid, packed-column gas chromatographic method was developed for simultaneous determination of 10 pyrethroid insecticide residues (allethrin, biphenthrin, cyhalothrin, permethrin, cyfluthrin, flucythrinate, fenvalerate, fluvalinate, deltamethrin, and py-115) in fruits, vegetables, and grains. These multiresidues are extracted from various crops with acetone–petroleum ether and cleaned up on a Florisil column (for the fruits and vegetables) or on a Florisil–charcoal–alumina column (for the grains) prior to their determination by gas chromatography with an electron capture detector. Recoveries of 10 pyrethroid compounds from 12 different crops (maize, soybeans, wheat, sorghums, paddy, potatoes, cucumbers, cauliflowers, spinaches, apples, bananas, and oranges) fortified at levels of 0.02–5.00 ppm ranged from 58 to 130%. In a separate precision study, coefficients of variation were 5.5–14.6% at 0.1–0.5 ppm (n = 10, maize), and 4.1–12.1% at 0.010–0.050 ppm (n = 10, apples). The detection limits of the method ranged from 2.0 to 10.0 ppb on a crop basis.
Voltametric Behavior of Zopiclone: Polarographic Determination in Tablets
Authors: Squella Juan A , Sturm Juan C , Alvarez-Lueje Alejandro , Núñez-Vergara Luis J
Published: February 2020

Electrochemical reduction of zopiclone at different pHs and concentrations was studied by polarography and cyclic voltametry. Both techniques revealed a reduction process with weak adsorption of both zopiclone and its reduction derivative. Zopiclone exhibited 2 differential pulse polarographic peaks at the dropping mercury electrode. The first peak was used to develop a differential pulse polarographic analytical procedure for determining the drug in pharmaceutical dosage forms. Reproducibility and recovery coefficients of variation were 1.6 and 2.2%, respectively. Analysis of commercial zopiclone tablets showed uniformity in zopiclone content. The method is simple and rapid because separation of excipients is unnecessary.
Automated Analysis with Computerized Information Transfer in a University Hospital
Authors: Bachmann Claude , Boulat Olivier
Published: February 2020

The organization of a central clinical chemistry laboratory of a university hospital, which in 1992 analyzed 880 000 results, is presented. Automation with midsize selective analyzers, which run in parallel and are able to do positive sample identification on the primary bar-coded tubes, in connection with a laboratory computer system and a central hospital computer allowed for reliable and timely obtainment of results. The output of the results is made on laser printers in the medical wards, thus alleviating the pneumatic sample transport systems. Assessment of the turnaround time show that it can be kept below one hour. Such a setup without sorting out emergency demands allows a simplified sample flow. Thus, there is no need for a laboratory to make “stat” requests.
Development of Data Sets for the Validation of Analytical Instrumentation
Authors: Ellison Stephen L R , Cox Maurice G , Forbes Alastatr B , Butler Bernard P , Hannaby Simon A , Harris Peter M , Hodson Susan M
Published: February 2020

Analytical chemistry makes use of a wide range of basic statistical operations, including means; standard deviations; significance tests based on assumed distributions; and linear, polynomial, and multivariate regression. The effects of limited numerical precision, poor choice of algorithm, and extreme dynamic range on these common statistical operations are discussed. The effects of incorrect choice of algorithm on calculations of basic statistical parameters and calibration lines are illustrated by examples. Some approaches to validation of such software are considered. The preparation of reference data sets for testing statistical software is discussed. The use of ‘null space’ methods for producing reference data sets is described, and an example is given. These data sets have well-characterized properties and can be used to test the accuracy of basic statistical procedures. Specific properties that are controlled include the numerical precision required to represent the sets exactly and the analytically correct answers. A further property of some of the data sets under development is the predictability of the deviation from the expected results resulting from poor choice of algorithm.
Automation and Quality in Analytical Laboratories
Authors: Valcárcel Miguel , Ríos Angel
Published: February 2020

After a brief introduction to the generic aspects of automation in analytical laboratories, the different approaches to quality in analytical chemistry are presented and discussed to establish the following different facets emerging from the combination of quality and automation: automated analytical control of quality of products and systems; quality control of automated chemical analysis; and improvement of capital (accuracy and representativeness), basic (sensitivity, precision, and selectivity), and complementary (rapidity, cost, and personnel factors) analytical features. Several examples are presented to demonstrate the importance of this marriage of convenience in present and future analytical chemistry.
Screening Procedure for Organochlorine and Organophosphorus Pesticide Residues in Eggs using a Solid-Phase Extraction Cleanup and Gas Chromatographic Detection
Authors: Schenck Frank J , Wagner Roberta , Hennessy Michael K , Okrasinski Joseph L
Published: February 2020

A solid-phase extraction (SPE) screening procedure for the isolation and gas chromatographic (GC) determination of organochlorine and organophosphorus pesticide residues in eggs is described. Eggs are extracted with acetonitrile. The extract is subjected to a cleanup on tandem C18 and Florisil SPE columns. Organochlorine and organophosphorus pesticide residues are determined by GC with electron capture and flame photometric detection, respectively. Because the injected extracts are free from matrix interferences, the amount of residue present is easy to calculate. The average recoveries of 9 spiked organochlorine pesticide residues (0.01–1.0 ppm) ranged from 80.9 to 91.1 %. The average recoveries of 7 spiked organophosphorus pesticide residues (0.02–0.50 ppm) ranged from 80.3 to 89.5%. The SPE method results in a 90% reduction in organic solvent consumption and an 85% reduction in hazardous waste production compared with the AOAC methodology.
Influence of pH, Ionic Strength, and Physical State on the Near-Infrared Spectra of Model Compounds
Authors: Reeves James B
Published: February 2020

The accuracy of near-infrared spectroscopy (NIRS) when applied to high-moisture samples (i.e., silages) does not match that with dried materials. Previous work showed that the presence of water could cause shifts in the spectra of organic compounds, the degree of which depended on the material and the water concentration. For some solids, such as sugars, large spectral changes occur on dissolution. The objective of this study was to determine the effect of pH, ionic strength, and physical state on the NIR spectra of model compounds. The results show that pH has large effects on the spectra of amines and acids but little if any on the spectra of ketones, alcohols, and sugars. The spectra of peptides and proteins also were pH dependent, but that of cellulose was not. Ionic strength differences (deionized water vs saturated NaCI solution as the diluting media) had only minor or no effect on the spectra of the materials studied. The effect of physical state was far more complicated; the spectra of freeze-dried glucose and glycine were different from that of the crystalline forms, but the spectrum of serine was not. The spectra of molten compounds often appeared like those of solutions. These results, in agreement with earlier work, may explain the poorer performance of NIRS with wet materials compared with dry samples. They also have serious implications for the analysis of dried samples, if pH, ionic strength, or drying method varies among samples.
Preparation of Milk Samples for Immunoassay and Liquid Chromatographic Screening Using Matrix Solid-Phase Dispersion
Authors: Barker Steven A , Long Austin R
Published: February 2020

The use of drugs to maintain the health and maximize the output of dairy cattle has made the monitoring of milk for such agents essential. Screening tests based on immunological, microbial inhibition, and bacterial receptor assays have been developed for the detection of violative levels of therapeutic substances. However, such assays are not infallible, and false positive or negative results can occur when contaminants bind receptors or compete for the binding of the target residues. Such effects may arise from dietary sources, diseases, or other variables. Thus, a violation by such a test is not definitive until further confirmation is obtained. Our laboratory has developed extraction procedures for several drugs used in dairy production. Our method uses matrix solid-phase dispersion (MSPD) to isolate drugs away from contaminants and to eliminate many possible interferences. MSPD can also be used to enhance the specificity of such assays by fractionating various classes of drugs that may cross-react. Similarly, such methods may be used for liquid chromatographic screening and confirmation of a suspect sample.
Improvement of Chemical Analysis of Antibiotics. Part XIX1: Determination of Tetracycline Antibiotics in Milk by Liquid Chromatography and Thin-Layer Chromatography/Fast Atom Bombardment Mass Spectrometry
Authors: Oka Hisao , Ikai Yoshttomo , Hayakawa Junko , Masuda Katsuyoshi , Harada Ken-Ichi , Suzuki Makoto
Published: February 2020

A precise liquid chromatographic (LC) determination with high sensitivity and a reliable mass spectrometric (MS) confirmation were established for the determination of tetracycline antibiotics (TCs) in milk. The determination of the TCs was based on C18 cartridge cleanup followed by LC separation. Recoveries of TCs from milk fortified at 20 ppb were 73.0–81.8%, and coefficients of variation were 2.6–4.6%. With this method, concentrations of oxytetracycline and tetracycline as low as 10 ppb and chlortetracycline and doxycycline as low as 20 ppb were determined readily. Thin-layer chromatography (TLC)Zfast atom bombardment (FAB) MS with a condensation technique was used to confirm TCs in milk. After the C18 cartridge cleanup, separation on a C18 TLC plate, and application of the sample condensation technique, FAB mass spectra were measured. TCs in milk at 50 ppb were reliably confirmed by TLC/FABMS.
Extraction and Enzyme Immunoassay of Sulfadimethoxine Residues in Channel Catfish (Ictalurus punctatus) Muscle
Authors: Walker Calvin C , Barker Steven A
Published: February 2020

Four commercially available enzyme immunoassays were evaluated for the detection of sulfadimethoxine (SDM) residues in channel catfish muscle. Matrix solid-phase dispersion (MSPD) extracts of samples (n = 60, 0.5 g) fortified with SDM at 0, 25, 50, 100, and 250 ng/g were used in all assays. Intra-assay variations for 2 MICROTITER well-based quantitative assays, SIGNAL sulfamethazine test and IDS SDM One-Step ELISA (enzyme-linked immunosorbent assay), were 5.6 and 7.7%. Interassay variations for these tests were 7.9 and 16.6%. The agreements between evaluators for 2 membrane-based, visually determined assays, CITE Sulfa Trio and EZ-SCREEN: SDM, were 77 and 95%. Performance values, as indicated by sensitivity, specificity, efficiency, and positive and negative predictive values, were 100, 92, 95, 89, and 100%, respectively for the SIGNAL test; 100, 94, 97, 92, and 100% for the IDS test; 98, 71, 82, 69, and 98% for the CITE test; and 98, 94, 96, 92, and 99% for the EZSCREEN assay. Eight sulfonamides cross-reacted in the SIGNAL test; EC-50 values (concentrations causing 50% inhibition of color development compared with blanks) varied from <0.1 to 45 μg/mL. The EC-50 value for SDM was 0.25 μg/mL. The CITE test cross-reacted with sulfachloropyridazine at 10 μg/mL. The IDS and EZ-SCREEN tests had no significant cross-reactivity with other sulfonamides. N-Acetyl SDM reacted like the parent SDM in all assays. Performance results indicated that MSPD extracts of catfish muscle may be used in these immunoassays to screen catfish muscle samples for violative levels of SDM residue.
Gas Chromatographic Determination of Total Fat Extracted from Food Samples Using Hydrolysis in the Presence of Antioxidant
Authors: House Stephen D , Larson Paul A , Johnson Rodney R , DeVries Jon W , Martin Dianna L
Published: February 2020

A method for the quantitative measurement of total fat in foodstuffs is described. Fat is extracted by hydrolysis and interesterified to fatty acid methyl esters for gas chromatographic analysis. Total fat and fatty acid patterns are calculated to comply with the regulations for food label declaration under the Nutrition Labeling and Education Act of 1990. Quantitative recovery of fat from soy oil is obtained in the presence of the antioxidant pyrogallol. Extraction and measurements of fat from a variety of food samples (e.g., cereal, baked goods, dairy, and fish) are also reported, and fat levels ranged from 0.8 to 95% (w/w). Coefficients of variation of ≤5% demonstrate the efficiency of the method.
Performance Evaluation of the Babcock and Ether Extraction Methods: 1989 through 1992
Authors: Lynch Joanna M , Barbano David M , Healy Patrick A , Richard Fleming J
Published: February 2020

Results of the collaborative studies of the performance of the Babcock method (989.04) and the modified Mojonnier ether extraction method (989.05) for the determination of the fat content of raw milk were published in 1988. Method performances were characterized by using the harmonized International Organization for Standardization–International Union of Pure and Applied Chemistry–Association of Official Analytical Chemists (ISO/IUPAC/AOAC) guidelines for method validation, and the methods were approved official first action. During 1989 through 1992, the split-sample collaborative study format was used to monitor the performance of these methods as a part of an ongoing quality assurance program for a group of laboratories. Seven blind duplicate samples of raw milk were sent from a central laboratory once every 2 months to each participating laboratory (11 to 17 laboratories). Data were analyzed by using the same statistical procedures used in the 1988 study. Over time, both the within- and between-laboratory performances of both methods were as good as or, in most cases, better than the results from 1988. The data demonstrate that the statistical protocol for collaborative studies can be used effectively as the basis for a multilaboratory quality assurance program and that the method performance achieved in a collaborative study can be maintained and even improved with time.
Ion Chromatographic Method for Dissolved Hexavalent Chromium in Drinking Water, Groundwater, and Industrial Wastewater Effluents: Collaborative Study
Authors: Edgell Kenneth W , Longbottom James E , Joyce Robert J
Published: February 2020

A collaborative study was conducted by the U.S. Environmental Protection Agency (U.S. EPA) and the American Society for Testing Materials (ASTM) on an ion chromatographic method for the determination of hexavalent chromium (U.S. EPA method 218.6, and the ASTM equivalent method). This study was designed to determine the mean recovery and precision of analyses for hexavalent chromium in reagent water, drinking water, groundwater, and industrial wastewaters. The study design was based on Youden’s nonreplicate plan for collaborative studies of analytical methods. The test waters were spiked with hexavalent chromium at 8 concentration levels, prepared as 4 Youden pairs. A fifth Youden concentration pair was also included to determine method performance close to the method detection limit. Twenty-one laboratories were instructed to filter their test waters through a 0.45 μm filter and to adjust the pH of the filtrate to 9–9.5 with an ammonium sulfate/ammonium hydroxide buffer solution before spiking with the hexavalent chromium concentrates. A known volume, 50–250 (μL, was injected into an ion chromatograph which separated the Cr(VI), as CrO42−, on an anion exchange column. After separation, the Cr(VI) was derivatized with diphenylcarbazide and the colored complex was detected at 530 nm. The submitted data were corrected for background concentrations and analyzed by applying ASTM D-2777-86 statistical procedures and a U.S. EPA computer program. U.S. EPA method 218.6 and the equivalent ASTM method were judged acceptable for the measurement of hexavalent chromium concentrations at 1–1000 μg Cr(VI)/L. The study found that the use of a single linear calibration extending over 3 orders of magnitude yielded biased results at the very lowest concentration levels. Shorter range calibration curves yielded more accurate results. Analysis of variance (ANOVA) tests indicated that method performance was significantly different between the reagent water matrix and the other matrixes used. The recovery of Cr(VI) from the other matrixes was lower at all concentration levels with slightly less precision when compared with the reagent water data set. For reagent water, the mean recovery and the overall and single-analyst relative standard deviations were 105%, 7.8% and 3.9%, respectively. For the other matrixes, the same values were 96.7%, 11.9% and 6.3%, respectively. The method was adopted first action by AOAC INTERNATIONAL.
Determination of Diclazuril in Avian Feed and Premixes with Gas Chromatography/Mass Spectrometry
Authors: Blanchflower W John , Hughes Peter J , Cannavan Andrew , Kennedy D Glenn
Published: February 2020

A method is presented for the determination of the relatively new anticoccidial drug diclazuril in avian feed and premixes. The drug was extracted from feed with acidified methanol-water, and the extracts were cleaned up by simple liquid-liquid extraction. These were then derivatized with ethereal diazomethane, and the methyl derivatives were analyzed by gas chromatography/mass spectrometry on a bench-top instrument An internal standard was used to enhance the reproducibility and ruggedness of the assay. The coefficients of variation for a finished feed and premix assayed 5 times each on 3 occasions were 6.6 and 6.0%, respectively. The detection limit of the assay is about 0.02 mg/kg, which is adequate for measuring the normal inclusion rate of 1 mg/kg in finished feed.
Determination of Reserpine, Hydralazine HCl, and Hydrochlorothiazide in Tablets by Liquid Chromatography on a Short, Normal-Phase Column
Authors: Cieri Ugo R
Published: February 2020

A procedure is presented for the determination of reserpine, hydralazine HCI, and hydrochlorothiazide in tablets by liquid chromatography. The sample is extracted with methanol, and the extract is filtered through paper. Chromatography is performed in 2 stages, each using a 7.5 cm-long normal-phase column but different mobile phases. In the first stage, intended exclusively for reserpine, the mobile phase consists of methanol containing 2% aqueous 1-pentanesulfonic acid sodium salt at 4 parts/1000. Detection and quantitation of reserpine was by fluorescence at 280 nm (excitation) and 360 nm (emission). In the second stage, the amount of the salt solution in the mobile phase was increased to 5%. Detection and quantitation of hydrochlorothiazide and hydralazine HCI was by UV absorbance at 260 nm. One commercial sample of tablets was analyzed by the proposed method. Two determination of each ingredient were made on a ground composite. Ten individual tablets also were examined.
Determination of Thiabendazole in Fruits and Vegetables by Competitive-Inhibition Enzyme Immunoassay
Authors: Bushway Rodney J , Young Barbara E S , Paradis Lance R , Perkins Lewis B
Published: February 2020

An enzyme immunoassay (EIA) was developed for analysis of thiabendazole (TBZ) in fruits and vegetables. A commercial kit using a polyclonal antibody for benomyl-carbendazim was used. Total analysis time, including sample preparation, was 35 min. As many as 8 samples can be analyzed simultaneously, with a limit of quantitation of 9 ppb. The assay's dynamic range ran from 9 to 304 ppb TBZ. Intra-as-say coefficients of variation (CVs) ranged from 5.0 to 9.6% for standards and 11 to 30% for samples. In-terassay CVs varied from 4.4 to 15% for standards and from 10 to 24% for samples. Average recovery from 29 samples spiked at 50-50 000 ppb was 116%. A total of 107 food products comprising 12 different fruits and vegetables and their processed products were analyzed for their TBZ content by EIA and liquid chromatography (LC). Of these samples, 84 were positive for TBZ by both methods, with a correlation coefficient (r) of 0.989. Eight samples had none detected by either technique, and 15 were positive for carbendazim. Concentrations of TBZ ranged from 11 to 94 000 ppb. The immunoassay with methanol sonication shows promise as a rapid screening method for TBZ in foods.
Analysis of Methyl Isothiocyanate in Wine by Gas Chromatography with Dual Detection
Authors: Satto Isao , Yamada Sadaji , Oshtma Harumi , Ikai Yoshttomo , Oka Hisao , Hayakawa Junko
Published: February 2020

Methyl isothiocyanate (MITC) was extracted from a 5 mL wine sample with 2 mL dichloromethane, and the extract was washed with 5% sodium chloride solution. MITC was determined by gas chromatography with a dual nitrogen-phosphorus detector (NPD) and a flame photometric detector (FPD, S mode) (DB-210 column, 30 m × 0.53 mm id, column temperature, 70°C). The limit of detection and quantitation of MITC with NPD–GC were 0.003 and 0.01 ppm, respectively. Average recoveries of MITC added to wine at 1 and 0.1 ppm were over 95%. This method is simple and rapid for routine analysis of MITC in wine.
Validation of Computerized Liquid Chromatographic Systems
Authors: Furman William B , Layloff Thomas P , Tetzlaff Ronald F
Published: February 2020

Almost all vendors of liquid chromatographs offer dedicated computer-based controller/data-processing systems. These systems are integrated into the operation of the equipment and frequently use pro-prietary software systems for which complete documentation and program listings are not available to the user. In some instances, data in magnetic media are considered to be “raw data” for regulatory retention requirements. In addition, printed copies of final data used to make decisions and the procedures used to generate these data from raw data must be prepared and retained. In all cases, the systems must be validated to demonstrate that they are suitable for their intended uses. Approaches to validation of these systems are described and discussed.
Display Methods for Visual Comparison of the Results of Two Measurement Methods
Authors: Hartmann Christa , Massart Desiré L
Published: February 2020

The use of a plot originally proposed by Bland and Altman (1986, Lancet 8,307-310) for the comparison of 2 clinical measurement methods was investigated and compared with a new visual display based on principal component analysis. The characteristics of both methods are demonstrated for several computer-simulated situations. For visual comparison of 2 methods, it is recommended to use the 2 methods simultaneously, together with a plot of the results of method 2 against method 1.
Identification of Vibrio vulnificus by Cellular Fatty Acid Composition Using the Hewlett-Packard 5898A Microbial Identification System: Collaborative Study
Authors: Landry Warren L
Published: February 2020

A gas chromatographic method using a capillary column for rapid identification of Vibrio vulnificus was examined in a collaborative study. Identifications were performed by analysis of cellular fatty acid profiles which were automatically searched against reference profiles stored in a computer-generated library. Each of the 13 collaborators was sent 15 unknown isolates, which included 10 V. vulnificus isolates and 5 negative control isolates. Each collaborator was furnished with a computergenerated library, developed by the Dallas U.S. Food and Drug Administration laboratory, which contained entries for V. vulnificus, V. cholerae, V. fluvialis, V. parahaemolyticus, V. mimicus, and Aeromonas hydrophila. Of the 195 isolates sent to the collaborators, results for 190 isolates were received. The other 5 isolates were nonviable before analyses began. Of the 126 V. vulnificus isolates analyzed, 118 (93.7%) were correctly identified. Of the 65 negative control isolates sent, one was nonviable, one was misidentified as V. vulnificus, and 2 were misidentified as V. parahaemolyticus. Of the 64 negative controls analyzed, 95.3% were correctly identified. Statistical analysis shows a sensitivity rate of 0.872, specificity rate of 0.982, false positive rate of 0.010, and false negative rate of 0.206. The gas chromatographic method for identification of Vibrio vulnificus by microbial fatty acid profile has been adopted first action by AOAC INTERNATIONAL.
Dibenzoyl Methane—A New Coupling Agent for Nitrite Determination
Authors: Shanthi K , Balasubramanian N
Published: February 2020

Dibenzoyl methane is introduced as a new coupling agent for the determination of nitrogen dioxide in air and for nitrite in water and soil samples. Nitrogen dioxide is fixed as nitrite in NaOH–sodium arsenite trapping solution and also in triethanoamine trapping solution. The method is based on the diazo coupling reaction of p-nitro aniline with a new coupling agent, dibenzoyl methane. The azo dye formed under aqueous alkaline condition has an absorption maximum at 520 nm and obeys Beer’s law over a range of 0–20 μg nitrite per 10 ml analyte. The dye formed is stable for 40 h. The relative standard deviation is 2.8% for 10 determinations at 10 μg nitrite per 10 ml analyte. The color system upon extraction with isobutyl methyl ketone–amyl alcohol (1+1) shows a λ max at 520 nm and a Beer’s law range of 0–4 μg nitrite. The developed color is stable for 7 h in the organic phase. The relative standard deviation is 3.0% for 10 determinations at 2 μg nitrite. The molar extinction coefficient of the color system is 3.6 × 104 L/(mol·cm). The effect of interfering gases and ions on the determination is described. The method was applied to the determination of residual amounts of nitrogen dioxide present in the laboratory fume cupboard and in automobile exhaust gas. The method was also applied to the determination of nitrite and nitrate in water and soil samples. The results obtained were compared with the standard sulfanilamide–NEDA (N-1 naphthyl ethylene diamine dihydrochloride) method. The method can be used to determine levels as low as 0.5 μg nitrite in aqueous medium and 0.1 μg nitrite upon extraction.
Determination of Thiabendazole Residues in Pears by Solid-Phase Spectrofluorimetry
Authors: Cápitan-Vallvey Luis Fermin , Avidad Ramiro , Vilchez Jose Luis
Published: February 2020

An analytical procedure for determination of thiabendazole (TBZ) residues in pears is described. The method involves extracting the chemical from the chopped fruit with buffer solution (acetic acid–acetate, pH 4.6), use of Sephadex G-15 dextrantype gel as a solid support, and determination of TBZ by solid-phase spectrof luorimetry (SPF). The relative fluorescence intensity of the Sephadex G- 15 gel–TBZ system, packed in a 1 mm-thickness silica cell, was measured directly at λex = 303 nm and λem = 350 nm with a solid-phase attachment. The applicable concentration range was 5.0–20.0 ppb with a detection limit of 0.5 ppb. Recoveries were from 98.7 to 102.0% when 15.0 ppb of TBZ was added to the fruit.
Effectiveness of a One-Day Procedure for Recovery of Salmonella from Milk Powders
Authors: Hammack Thomas S , Andrews Wallace H , Amaguana R Miguel , June Geraldine A , Sherrod Patricia S
Published: February 2020

A rapid procedure for enumerating Salmonella in milk powders was evaluated. Dry whole milk and instant nonfat dry milk were rehydrated, artificially inoculated with various numbers of Salmonella cells, and stomached. Test portions were then treated with Tween 80 and pancreatic trypsin, and incubated for 1 h at 30°C. The incubated test portions were centrifuged at 10 000 × g for 15 min at 5°C, and the resuspended pellets were plated on xylose lysine desoxycholate agar. The effectiveness of the procedure was expressed in terms of percentage recovery of the inoculum. The procedure, which was evaluated in 76 trials using 7 Salmonella serovars, recovered ≤73% of the inoculum for half of the trials conducted. Its effectiveness was dependent on the serovar, level of inoculation, and type of milk powder used.
Cholesterol Analysis in Foods by Direct Saponification—Gas Chromatographic Method: Collaborative Study
Authors: Klatt Low V , Mitchell Barbara A , Smith Randall L
Published: February 2020

A collaborative study was conducted on a method for determination of cholesterol in various foods and food products using a direct saponification technique and capillary column gas chromatography. The method is a modification of AOAC Official Method 976.26 for the determination of cholesterol in multicomponent foods. The major modifications include the use of direct hot alkaline saponification and capillary column gas chromatograph to quantitate the cholesterol. Blind duplicate samples of butter cookies, hot dog buns (made with eggs), bread crumbs, vegetable-bacon baby food dinner, NIST (SRM No. 1845) egg powder, skinless wieners, commercial egg powder, vegetable-chicken baby food dinner, and Cheez Whiz were analyzed by 14 collaborators. The mean cholesterol values of these products ranged from less than 1.0 to 1965 mg/100 g. The average repeatability (RSDr) for all samples was 4.81%. The average reproducibility (RSDR) was 8.58% with only 2 products having RSDR values above 10%. These 2 products were the baby food dinner complex matrices with cholesterol values below 5 mg/100 g. The fact that the cholesterol levels for these dinner products are close to the level of quantitation is one explanation for the elevated RSDR values. The direct saponification—gas chromatographic method for determination of cholesterol in foods has been adopted first action by AOAC INTERNATIONAL.
Liquid Chromatographic Determination of Thiamine in Rodent Feed by Postcolumn Derivatization and Fluorescence Detection
Authors: Gehring Theresa A , Cooper Willie M , Holder Claude L , Thompson Harold C
Published: February 2020

A liquid chromatographic method was developed for determination of the essential nutrient thiamine (vitamin Bi) in rodent feed. Thiamine was extracted with hydrochloric acid, separated by reversed-phase liquid chromatography, derivatized postcolumn to thiochrome with potassium hydroxide and potassium ferricyanide, and detected by fluorescence. Excitation and emission wavelengths were 370 and 430 nm, respectively. Detector response was linear in the range of 2.58 to 15.5 ng of thiamine injected. Instrument detection limit was 5 pg of thiamine injected.
Determination of Sulfadimethoxine Withdrawal Time from Milk. Part II: Statistical Assessment
Authors: Lentz Ellen L , Chung Jain
Published: February 2020

A statistical method is proposed to establish milk discard time for the data set described in Part I (preceding paper). Results are compared with those from the Food and Drug Administration (FDA)-recommended method. The milk discard time is established on the basis of a calculated tolerance limit. This limit provides 95% confidence that 99% of the population residue would assay below the permitted concentration (10 ppb for SDM). Unlike the FDA method, the proposed method allows easy calculation and requires no assumptions in drug depletion rate over time. For a permitted concentration of 10 ppb, both methods confirm the present 60-h discard time for SDM when it is assumed that no more than ⅓ of the milk came from treated cows.
Modified Immunoassays for Polyether Toxins: Implications of Biological Matrixes, Metabolic States, and Epitope Recognition
Authors: Baden Daniel G , Melinek Rosemary , Sechet Veronique , Trainer Vera L , Schultz Duane R , Rein Kathleen S , Tomas Carmelo R , Delgado Jesus , Hale Lauren
Published: February 2020

Polyether marine toxins are responsible for the seafood intoxication phenomena known as neurotoxic shellfish poisoning (due to brevetoxins), ciguatera (due to ciguatoxin), and diarrheic shellfish poisoning (due to okadaic acid). Using traditional techniques of hapten (pure toxin) conjugation to protein to create complete antigen, animal immunization and antibody isolation, and specific antibody subpopulation purification, discriminating antibodies have been isolated that detect brevetoxins and ciguatoxin, but not okadaic acid, in a dose-dependent fashion. Using microorganic chemistry and purified toxins, a unique set of tools has been created for the study of polyether ladder toxin accumulation; depuration; and specific site localization in tissues, food sources, and clinical samples. Developed test protocols can detect toxin in dinoflagellate cells, in extracts from food sources, in seawater and culture media, and in human serum samples. Enzyme-linked immunosorbent assay protocols developed for eventual collaborative testing have been successful in limited applications within the laboratory (correlation coefficient of 0.92 excluding 2 outliers), and alternative formats are being developed to optimize the basic test for use in research laboratories, regulatory laboratories, and field inspections.