bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Paraquat and Diquat in Low-Moisture Food Crops Using Silica Column Cleanup and Liquid Chromatography with UV Detection
Authors: Chichila Tina M P , Gilvydis Dalia M 
Published: February 2020

Abstract
A sample cleanup method was developed for the determination of paraquat (PQ) and diquat (DQ) in low-moisture food crops. Low-moisture commodities, such as milled dry navy beans, are digested in acid. PQ and DQ are isolated from the digestates by using a 4 g column of preconditioned silica gel. The analytes are concentrated and then determined by liquid chromatography with a silica analytical column, sodium chloride as an ion-pairing reagent, and acetonitrile as an organic modifier. PD and DQ are determined simultaneously with a diode array UV absorbance detector. Recoveries for PQ and DQ were determined on 3 different fortified low-moisture crops. Fortification levels ranged from 0.01 to 0.30 ppm; average recoveries ranged from 47.5% (DQ) to 95.3% (PQ).
Interlaboratory Study of a Thermospray-Liquid Chromatographic/Mass Spectrometric Method for Selected N-Methyl Carbamates, N-Methyl Carbamoyloximes, and Substituted Urea Pesticides
Authors: Lopez-Avila Viorica , Jones Tammy L ,   Collaborators:, Anderson B , Behymer T , Christensen R , Dougherty T , Getek T , Ilnicki L , Richards D , Shalaby L , Vestal C 
Published: February 2020

Abstract
A thermospray-liquid chromatographic/mass spectrometric (TS-LC/MS) method was evaluated in an interlaboratory study for determining 3 N-methyl carbamates (bendiocarb, carbaryl, and carbofuran), 3 N-methyl carbamoyloximes (aldicarb, methomyl, and oxamyl), 2 substituted urea pesticides (diuron and linuron), and 1 ester of a substituted carbamic acid (carbendazim). The purpose of this study was to establish whether these 9 compounds can be reliably detected and quantitated with this method, and to establish the interlaboratory precision and accuracy of the method with currently available instrumentation. The study design was based on AOAC INTERNATIONAL’S blind replicate design with balanced replicates. The samples consisted of solutions of the 9 test compounds in methanol at 3 concentrations that were unknown to the participating laboratories and that covered the linear range of the method. Nine volunteer laboratories participated in the study. Linear regression equations are presented that calculate the accuracy of the method, i.e., the percent recovery of each of the 9 compounds at any concentration within the range of concentrations tested (5–90 (μg/mL for each compound, except carbendazim, for which the range was 1.25–22.5 μg/mL). The intra laboratory precisions of the TS-LC/MS method ranged from 6.5 to 33.1 % relative standard deviation, depending on the compound. The interlaboratory method precisions ranged from 29.8 to 98.2% relative standard deviation over the concentration range tested. Analysis of variance indicates that for all compounds tested, the variation from laboratory to laboratory is greater than that attributed to analytical error displayed within laboratories. There are many operational parameters that could contribute to interlaboratory variability; one of them, the thermospray tip temperature, can play a major role in adduct formation and ion fragmentation in the case of thermally labile carbamate pesticides and, therefore, needs to be monitored and controlled carefully. The correlation of mass spectral data with the thermospray tip temperature was attempted using principal component analysis.
Determination of Formetanate Hydrochloride in Selected Fruits by Coupled-Column Cation Exchange Liquid Chromatography
Authors: Niemann Richard A 
Published: February 2020

Abstract
A strong cation exchange (SCX) liquid chromatographic (LC) method is described for determination of formetanate hydrochloride residue in pome, citrus, and stone fruits. A test portion of fruit, homogenized with the peel left on, was blended with acidified acetonitrile and filtered. A portion of extract was finely filtered, and a 500 μL aliquot (ca 0.2 g test sample equivalent) was loaded onto an SCX solid-phase extraction (SPE) LC column, which replaced the injection loop of the LC injection valve. Cations were selectively enriched; noncations were eluted by acetonitrile in a pre-separation cleanup. Turning the valve to the inject position coupled the SPE column to an SCX analytical column for separation and detection at 250 nm. The mobile phase was 0.4M pH 3.0 ammonium phosphate buffer–water–acetonitrile (50 + 25 + 25). Formetanate cation was quantitated by peak area and regression coefficients from a 5-point linear calibration covering a 100-fold range. Recovery of duplicate fortifications of apple, pear, orange, and peach averaged 89–99% at the respective U.S. tolerances of 3,3,4, or 5 ppm and averaged 93–99% at onetenth of the respective tolerance level. Peel pigments or variable peel bulk of crop varieties tested, as well as other endogenous fruit material, contributed interference that was below the 0.02 ppm limit of detection. In a 1991 limited survey comprising 15 samples, none were found violative. Residues were found in 2 samples, but only 1 measurement was quantifiable, near the 0.06 ppm limit of quantitation.
Fluorometric Determination of Total and Bound Sulfite in Wine by N-(9-Acridinyl)maleimide
Authors: Akasaka Kazuaki , Ohrui Hiroshi , Meguro Hiroshi , Suzuki Tateo , Miwa Harufumi 
Published: February 2020

Abstract
N-(9-Acridinyl)maleimide (NAM) reacts with sulfite in wine and gives strong fluorescent derivatives that lead to highly sensitive fluorometry of both total and bound sulfite in wine. Values of free and bound sulfite in wine determined by the NAM method and the modified Rankine method agreed. Sulfite was determined in &lt;200 μL wine within 2 h.
Determination of Sulfur Dioxide in Wines and Beverages by Flow Injection Analysis with Reductive Amperometric Detection and Electrolytic Cleanup
Authors: Cardwell Terence J , Cattrall Robert W , Nan Chen Guo , Cardwell Terence J , Scollary Geoffrey R , Hamilton Ian C 
Published: February 2020

Abstract
A new flow injection method is described for the determination of sulfur dioxide in red and white wines and other beverages. A dual-electrode electrochemical detector eliminates interferences by reduction at an upstream coulometric electrode before reductive detection of sulfur dioxide at the amperometric electrode. The data for free and total sulfur dioxide in wines and other beverages agree well with those obtained by the standard aspiration oxidation method.
Determination of AmpiciUin and Amoxicillin in Milk with an Automated Liquid Chromatographic Cleanup
Authors: Moats William A 
Published: February 2020

Abstract
A method is described for determination of am-piciitin and amoxicillin in milk by using an automated liquid chromatographic (LC) cleanup. Milk was deproteinated by adding tetraethylammonium chloride solution and acetonitrile. The filtrate was concentrated by evaporation, filtered, and loaded into a 4 mL autosampler vial. For LC cleanup, a Waters W1SP 712 autosampler, a Varian 9010 pump, a Supelcosil LC-18 column, and an ISCO FOXY fraction collector were used. The cleanup program, where A is 0.01 M KH2PO4 and B is acetonitrile, was 100A + OB for 0-3 min and then 70A + 30B for 24 min. Sample concentrate (2 mL) was loaded onto the column for cleanup. Fractions containing amoxicillin and ampicillin were collected, partially acidified, and concentrated to 1 mL. Analysis was done on the LC-18 column, with a mobile phase of 0.015M H3PO4–{0.0075M sodium dodecyl sulfate-acetonitrile (70 + 30)] for amoxicillin and 0.0067M H3PO4–0.0033M KH2PO4–[0.005M sodium dodecyl sulfate–acetonitrile (67 + 33)] for ampicillin. Recoveries were generally 80–90% at a concentration range of 1–0.01 ppm, with a detection limit of 2–5 ppb. By collecting appropriate fractions, the method can be applied to the determination of any amphoteric β-lactam.
Determination of Captan in Water, Peaches, and Apple Juice by a Magnetic Particle-Based Immunoassay
Authors: Itak Jeanne A , Selisker Michele Y , Herzog David P , Fleeker James R , Bogus Edward R , Mumma Ralph O 
Published: February 2020

Abstract
A magnetic particle-based enzyme-linked immunosorbent assay (EUSA) was used to determine captan residues in water, peaches, and apple juice. Precision studies of captan-spiked water samples showed coefficients of variation (CVs) of 24% at 0.1 ppm and 15% at 2.0 ppm. Average recoveries from water were 110–118%, with an estimated sensitivity of 0.01 ppm for captan. Low cross-reactivity was seen with the related phthalimide fungicides capta-fol and folpet. A least-detectable dose (LDD) of 1 ppm was estimated for captafol in the immunoassay; an LDD of 8.6 ppm was estimated for folpet. Apple juice samples were analyzed by a 3-step procedure: the sample was concentrated on a Cis bonded silica solid-phase column, the eluate was diluted in buffer, and the sample was assayed by ELISA. The detection limit in apple juice was estimated to be 0.1 ppm on the basis of the detection limit observed in water and the required calculation factors; the average recovery was 115%. Acetone extraction, Cis bonded silica solid-phase extraction column, and the immunoassay were used consecutively to analyze peach samples. The detection limit in peaches was estimated to be 0.15 ppm on the basis of the detection limit observed in water and the required calculation factors. Captan residues were found in all but one of the peach samples and ranged from 0.15 to 1.12 ppm (|ig/g). Recovery of added captan from peaches averaged 98% for both spike levels tested. Results of analysis of captan in peaches by immunoassay and gas chromatography with electron capture detection (GC/ECD) were compared. GC/ECD gave an average recovery of 75%; immunoassay gave an average recovery of 112%.
Elevated-Temperature, Colorimetric, Monoclonal, Enzyme-Linked Immunosorbent Assay for Rapid Screening of Salmonella in Foods: Collaborative Study
Authors: Eckner Karl F , Dustman Wendy A , Curiale Michael S , Flowers Russell S , Robison Barbara J 
Published: February 2020

Abstract
A collaborative study was performed by 30 laboratories in 3 sets of trials to validate a modified colorimetric monoclonal enzyme-linked immunosorbent assay (ELISA) method for Salmonella detection. The modifications to the current methodology included incubation of enrichments and postenrichments at an elevated temperature, addition of novobiocin to the M-broth post-enrichment, and elimination of the centrifugation and agitation steps. Five artificially contaminated foods (nonfat dry milk, milk chocolate, dried egg, ground black pepper, and soy flour) and 1 naturally contaminated food (raw ground turkey) were analyzed. The artificially contaminated foods were inoculated with individual Salmonella serotypes at a high (10–50 cells/25 g) and low (1–5 cells/25 g) contamination level. Results from the modified ELISA method were compared to the Bacteriological Analytical Manual (BAM)/AOAC culture method. In 2 of the food products, milk chocolate and pepper, a number of laboratories isolated Salmonella from uninoculated control samples, thus invalidating their data. As a result, there were too few laboratories remaining with valid data, and these foods were repeated. In the completed study, there were 11 false negative results obtained by the modified ELISA method, while there were 28 false negatives produced by the BAM/AOAC procedure. There were 11 ELISA positive assays which could not be confirmed by culture methods. Statistically, there were no differences between the modified, colorimetric, monoclonal ELISA and the reference culture method in all foods except raw turkey, where the ELISA method was more productive. The colorimetric monoclonal enzyme immunoassay (Salmonella-Tek) method for detecting Salmonella in all foods has been adopted first action by AOAC INTERNATIONAL.
Spectrophotometric Determination of Nitrate in Baby Foods: Collaborative Study
Authors: Sjöberg Anna-Maua K , Alanko Timo A 
Published: February 2020

Abstract
A collaborative study was conducted of a spectro-photometric method for determination of nitrate after cadmium reduction to nitrite in baby foods containing meat. Thirty-one municipal and 2 industrial food laboratories participated in the study. The study design involved 2 baby food matrices. Samples of both matrices were prepared at 3 concentration levels between 52 and 309 mg NaNO3/kg as blind duplicates. A blank without added nitrate was also included. The outlier percentage of the results was very low (4.3%). It was typical for the method that recoveries were slightly &gt;100%. Recoveries for baby foods varied between 113.3 and 116.9%, and were acceptable for control purposes. The relative standard deviations for repeatability were 5.0–18.1%. The relative standard deviations for reproducibility were 8.3–21.6%. Three collaborators also evaluated liquid chromatographic technique for nitrate determinations. These preliminary results are presented but are not analyzed statistically. The spectrophotometric method was adopted first action by AOAC INTERNATIONAL.
Comparison of Methods for Sampling Vadose Zone Soils for Determination of Trichloroethylene
Authors: Hewitt Alan D 
Published: February 2020

Abstract
This study compares 2 sampling and handling methods for the collection of soils to be analyzed for volatile organic compounds (VOCs). The currently accepted practice uses a vessel for the sole purpose of transferring and storing suspect soils from hazardous waste sites. This practice requires that the soil that is analyzed be handled at least twice: once when the vessel is filled on site and again when a subsample is removed for laboratory analysis. The sampling and handling protocol with which the current practice was compared limits sample exposure and disruption during collection and provides for sample acquisition during the field sampling exercise. The results confirm that sampling methods that limit disruption and exposure of soil samples are needed to obtain more accurate measurements of VOC concentrations in vadose zone soils.
Liquid Chromatographic Method for Analysis of the Naphthalene Dicarboxaldehyde Derivative of Fumonisins
Authors: Bennett Glenn A , Richard John L 
Published: February 2020

Abstract
A liquid chromatographic (LC) method for determining fumonisins in corn, feed, and laboratory cultures was optimized. We investigated the efficiency of extraction solvents, the performance of cleanup columns, the stability of fluorescent derivatives, and the efficiency of LC columns to separate deri-vatized fumonisins from interferences so that we could develop a sensitive, reliable assay for fumonisins. Maximum extraction efficiency was accomplished by shaking contaminated samples in acetonitrile–water (50 + 50, v/v) for 1 h; methanol–water mixtures and other ratios of acetonitrile–water were less efficient. Solid-phase extraction cleanups on reversed-phase Cia and strong anion exchange (SAX) columns were compared. The SAX columns were very efficient in isolating fumonisins from crude extracts; however, only the C18 columns could be used to partially purify fumonisin hydrolysis products. A highly fluorescent and stable derivative, prepared from naphthalene-2,3-dicar-boxaldehyde, proved to be suitable for LC analysis. Both parent compounds and hydrolysis products were separated in a simple gradient systjem of acetonitrile-acetic acid and water-acetic acid in less than 30 min.
Production of Carbon 14-Labeled Fumonisin in Liquid Culture
Authors: Blackwell Barbara A , Miller J David , Savard Marc E 
Published: February 2020

Abstract
A method for the production and purification of radiolabeled fumonisin that involves the addition of 14C-acetate to liquid cultures of Fusarium moniliforme in shake flasks is reported. Stable isotope 13C labeling studies were carried out using specifically enriched acetate and several amino acids to determine the location of labeled carbon atoms in the radiolabeled fumonisin that was also produced (650 μCi/mmol). These experiments determined that the 14C was distributed throughout the molecule making it useful for studies of fumonisin residues in animal products. Additionally, the 13C studies indicated that the biosynthesis of fumonisin involves the addition of methionine, glutarate, and serine or alanine to the hydrocarbon backbone. These data best fit the hypothesis that this backbone is polyketide in origin as opposed to being a modified lipid.
Liquid Chromatographic Determination of Sphmgamne and Sphingosine: Use of the Free Sphinganine-to-Sphingosine Ratio as a Biomarker for Consumption of Fumonisins
Authors: Riley Ronald T , Wang Elaine , Merrill Alfred H 
Published: February 2020

Abstract
Because the chemical structure of fumonisin B1 (FB1) has several structural features in common with the sphingoid bases, sphingosine and dihydro-sphingosine (sphinganine), we tested the hypothesis that the fumonisins might alter the normal cellular activity or the metabolism of endogenous free sphingoid bases. FB1 was found to be a potent inhibitor of de novo sphingolipid biosynthesis in vitro, its primary target being sphinganine N-acyl-transferase. This inhibition resulted in a decrease in the biosynthesis of sphingosine and an accumulation of free sphinganine, an intermediate in the de novo biosynthetic pathway for complex sphin-golipids. These findings led to the hypothesis that consumption of feed containing fumo|nisins should cause an increase in the ratio of free sphinganine to free sphingosine in tissues and serum. Data consistent with this hypothesis have been obtained from horses and pigs that consumed feed containing fumonisin-contaminated corn screenings and from rats fed feed supplemented with fumonisin-containing fungal culture materials or pure FBi. Thus, the ratio of free sphinganine to free sphingosine shows promise as a tissue, urine, or serum marker for animals consuming feed containing fumonisins. The present paper provides a detailed description of the extraction of free sphingoid bases and the liquid chromatographic method we used for determining the relative amounts of free sphingosine and free sphinganine in serum, urine, and various tissues of animals. Study results are summarized, and the ratio of free sphinganine to free sphingosine is discussed as a presumptive test for identifying animals consuming fumonisin-contami-nated feed.
Determination of Nitrofuran Residues in Poultry Muscle Tissues and Eggs by Liquid Chromatography
Authors: Kumar Luxmy , Toothell John R , Ho Koon-Bay 
Published: February 2020

Abstract
A liquid chromatographic (LC) method was developed and statistically validated for the determination of nitrofurazone, furazolidone, and furaltadone residues in poultry and porcine muscle tissues. The antimicrobial residues were extracted with a mixture of dichloromethane and ethyl acetate by using ultrasonication followed by solid-phase extraction cleanup and LC analysis with UV detection. A modification of the method incorporating acetonitrile extraction and solvent partition cleanup was developed for analysis of poultry eggs. The limits of detection were 1 μg/kg for nitrofurazone and furazolidone and 2 μg/kg for fural-tadone in both muscle tissues and eggs. Average recoveries for spike levels of 1,2, and 5 μg/kg ranged from 84 to 128%, and coefficients of variation were between 1.1 and 12.1%. Afield trial with these methods was conducted in conjunction with the Western Australian Department of Agriculture to determine the stability of furaltadone in both poultry tissue and eggs. Results of this study show that the concentration of furaltadone in muscle tissue diminished rapidly even when stored at −18°C. Furaltadone was considerably more stable in eggs.
Deoxyribonucleic Acid Hybridization Method for the Detection of Listeria in Dairy Products, Seafoods, and Meats: Collaborative Study
Authors: Curiale Michael S , Sons Terri , Fanning Luanne , Lepper Wendy , Mclver Dawn , Garramone Susan , Mozola Mark 
Published: February 2020

Abstract
The method is based on the hybridization of synthetic deoxyribonucleic acid probes to ribosomal ribonucleic acid sequences unique to Listeria. This method was compared to 2 culture methods: the U.S. Food and Drug Administration method for the detection of Listeria in dairy products and sea-foods and the U.S. Department of Agriculture, Food Safety and Inspection Service method for Listeria in meats. Six food types with replicate samples containing various concentrations of Listeria were analyzed by the collaborating laboratories. Listeria was detected in 774 samples using the DNAH method and in 772 samples using a culture method. The DNAH and culture methods were in agreement for 668 samples containing Listeria and 306 samples without Listeria. The overall rate of agreement between methods was 82.3%. The method has been adopted first action by AOAC INTERNATIONAL.
Gas Chromatographic Determination of Mono- and Diglycerides in Fats and Oils: Summary of Collaborative Study
Authors: Firestone David 
Published: February 2020

Abstract
A collaborative study was conducted on a capillary gas chromatographic method for the determination of mono- and diglycerides in fats and oils. Other components of fats and oils such as glycerol, fatty acids, and sterols may be analyzed by this method. Six materials used in the study consisted of 2 commercial mono- and diglyceride emulsifiers, 2 synthetic compositions with known amounts of monoand diglycerides in the presence of an excess of triglycerides, and 2 refined sunflower oils spiked with mono- and diglycerides. Eight laboratories participated in the study. On the basis of the collaborative study results, the method has been adopted first action by AOAC INTERNATIONAL as an IUPAC/AOCS/AOAC method.
Liquid Chromatographic Fluorescence Method for the Determination of Thiabendazole Residues in Green Bananas and Banana Pulp
Authors: Arenas Rene V , Johnson Nelson A 
Published: February 2020

Abstract
A novel liquid chromatographic method was developed for the determination of thiabendazole (TBZ) residues in whole green bananas and ripe banana pulp. TBZ is extracted from the banana matrix with ethyl acetate, followed by cleanup of extract on a cation-exchange, solid-phase extraction column. The extract is analyzed for TBZ residues by column liquid chromatography using a cation-exchange column with fluorescence detection. Recoveries of TBZ from whole green bananas fortified with TBZ at 0.05-10 ppm and from ripe banana pulp fortified with TBZ at 0.01-2 ppm averaged 93 and 95%, respectively. The following method for monitoring TBZ residues in whole green bananas and ripe banana pulp is simple, rapid, and sensitive.
Analysis of Flusilazole and Its Major Phenyl Metabolite (IN-F7321) by Approaches Based on Gas Chromatography
Authors: Guinivan Richard A , Gagnon Michael R 
Published: February 2020

Abstract
Two basic, previously unpublished procedures were developed to obtain flusilazole data for regula- tory purposes. One method involves extraction into ethyl acetate, cleanup on silica or Florisil, and analysis of flusilazole only by packed-column gas chromatography (GC) with nitrogen-phosphorus detection. The second method involves extraction into ethyl acetate, followed by gel permeation chro- matography and analysis by capillary GC with mass-selective detection for both IN-F7321 (major metabolite) and flusilazole. Several adaptations of the second procedure increase the analytical op- tions for flusilazole. The parent-only method was applied to analysis of more than 18 matrixes. The parent-plus-metabolite method and its adaptations were applied to the analysis of more than 33 ma- trixes. Cereals, fruits, animal matrixes and related processed fractions were analyzed. Average recov- eries for the parent-only method were generally above 90% (always above 80%) with standard devia- tions of 12% or less for fortifications ranging from 0.010 to 1.0 ppm. Average recoveries ranged from 84 to 108% for flusilazole and 82 to 111% for IN- F7321 fortifications from 0.010 to 2.0 ppm for the parent-plus-metabolite method. Standard devia- tions ranged from 3.6 to 20%.