bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid Chromatographic Determination of Flucytosine in Capsules
Authors: Shostak Donald , Klein Clifford 
Published: February 2020

Abstract
A liquid chromatographic method has been developed for determination of flucytosine in capsules. Flucytosine and p-aminobenzoic acid, the internal standard, are separated on a C18 reverse phase column using water-methanol-acetic acid mobile phase containing 1-octanesulfonic acid sodium salt. Compounds are detected photometrically at 285 nm. Mean assay results for 250 and 500 mg commercial capsules were 101.5% (n = 5) and 100.2% (n = 5) of declared, respectively. Mean recovery of flucytosine added to commercial capsules was 99.3 %.
Analysis for Total Sulfite in Foods By Using Rapid Distillation Followed By Redox Titration
Authors: Devries Jonathan W , Ge Hoon , Ebert Frank J , Magnuson Joel M , Ogawa Mark K 
Published: February 2020

Abstract
A rapid and accurate analysis for total sulfite as sulfur dioxide has been developed for foods and food products. The method, which combines a selective distillation cleanup procedure with the selective redox titration of sulfite ion by iodine, has been applied to a variety of foods and food products over a period of time with no significant interference encountered in any matrixes other than garlic and leeks. For the foods analyzed, the method typically shows a detection limit of 10 ppm, a relative standard deviation of 7.5% (compared with 10.4% for similar matrixes by the Monier-Williams method), and recoveries of 97.9 ± 6.4%. Comparison of results for this method with those obtained using the Monier-Williams method showed a mean value for the distillation/ titration method of 241 ppm compared with 242 ppm for the Monier- Williams method. A correlation of 0.991 and odds of a difference between methods of 10.7% (Student's paired t-test(1- α) × 100) were obtained for those matrixes where no interferences were encountered with either method.
Gas Chromatographic Determination of Fenpropimorph Residues in Citrus Fruit
Authors: Lafuente MarÍa Teresa , Tadeo José Luis , Tuset Juan José 
Published: February 2020

Abstract
A rapid gas chromatographic method for determining fenpropimorph residues in citrus fruit is reported. The fungicide is extracted with hexane after pH adjustment of the fruit homogenate. A short liquidliquid partitioning process is performed before gas chromatography on an OV-17 column with nitrogen-phosphorus specific detection. The limit of detection of the method was 0.01 mg/kg, based on a 25 g sample. Recovery was always higher than 70%. Fenpropimorph residues in "Washington Navel" oranges and "Hernandina" Clementine fruits dipped in a 1500 mg/L fungicide solution were determined. The fungicide remains mainly in the peel, with levels less than 0.1 mg/kg in the pulp. Fungicide residues in the peel decrease during storage, mainly in Washington Navel peel, where values decreased from 5.2 to 2.8 mg/kg.
Flame Absorption Spectroscopic Determination of Cadmium, Copper, Iron, Lead, and Zinc in Mussels
Authors: Solchaga Margarita , Montoro Rosa , Guardia Miguel Dela 
Published: February 2020

Abstract
A rapid method is proposed for determination of Cd, Cu, Fe, Pb, and Zn in mussel samples. The elements are extracted with concentrated nitric acid in borosilicate glass tubes at 90°C for 1 h, and determined by flame atomic absorption spectroscopy. Detection limits for a 300 mg sample corresponded to 0.3 μg Cd/g, 0.7 μg Cu/g, 33 μg Fe/g, 0.7 μg Pb/g, and 6 μg Zn/g. The coefficient of variation for 20 independent analyses was 7% for Cd, 7% for Cu, 6% for Fe, 14% for Pb, and 8% for Zn. Recoveries were 107 ± 3% for Cd, 90 ± 3% for Cu, 94 ± 1% for Fe, 90 ± 5% for Pb, and 96 ± 3% for Zn. The accuracy of the method was determined by analyzing NBS Oyster Tissues.
Atomic Absorption Spectrophotometnc Determination of Chromium in Foods
Authors: Farré Rosaura , Lagarda M Jesús , Montoro Rosa 
Published: February 2020

Abstract
A method is reported for determination of chromium in foodstuffs. Organic matter is digested with nitric acid, followed by oxidation to Cr(VI) and extraction with methyl isobutyl ketone (MIBK) after HC1 addition. Chromium determinations are performed by flame absorption spectroscopy. Absence of interferences is verified and recovery tests are performed on food samples. Quantitation limit (3.8 ng/mL), accuracy (NBS Standard Reference Material 1573 Tomato Leaves, 4500 ± 500 ng/g, found 3860 ± 409 ng/g), and precision (CV for vegetable matrix = 9.05%, CV for animal matrix = 14.95%) of the procedure are evaluated.
Kinetic Potentiometric Determination of Peroxidase in Plants, Using Fluoride-Selective Electrode
Authors: Skaltsa Helen D , Koupparis Michael A , Philianos Skevos M 
Published: February 2020

Abstract
A kinetic potentiometric method is described for the determination of peroxidases in vegetables and medicinal plants. It is based on the measurement of fluoride ion liberation rate from the peroxidase-catalyzed reaction of p-fluorophenol with hydrogen peroxide, sing the fluoride ion-selective electrode. The calibration curve is linear in the range 1-10 mU/mL with a precision of 1-3%. No interference was found from plant extracts, and recoveries were 97-107% (mean 100.9%). The method is rapid (2 min per measurement) and applicable to highly colored or turbid solutions. The method was applied for the determination of peroxidase activity in various plants of Greek flora. Plants of Leguminosae were found to be the richest source.
Carbon Isotope Ratios of Various Fruits
Authors: Krueger Dana A , Krueger Rae-Gabrielle , Krueger Harold W 
Published: February 2020

Abstract
Carbon stable isotope ratio analysis (SIRA) has been applied to detect adulteration of apple, orange, honey, and other products with cane or corn sugars. We analyzed numerous other fruits to determine the applicability of carbon SIRA to detecting adulteration in these fruits as well. The results indicate that the use of carbon SIRA may be generalized to most fruits of commercial importance.
Potential and Advantages of Immunochemical Methods for Analysis of Foods
Authors: Newsome W Harvey 
Published: February 2020

Abstract
The technique of immunochemical analysis, including the principles involved, is described and the various types of assay are discussed. Application of these methods to the analysis of foods for residues of pesticides, contaminants, drug residues, and natural constituents is reviewed. Compared with conventional methods, immunoassays offer similar detection limits and greatly simplified sample preparation procedures.
Liquid Chromatographic Determination and Identification of Morantel-Related Residues as Precursors of 3-(3-Methyl-2-Thienyl) Acrylic Acid (CP-20,107) in Bovine Milk
Authors: Lynch Martin J , Mosher Franklyn R , Brunner Linda A , Bartolucci S R 
Published: February 2020

Abstract
A simple liquid chromatographic (LC) method was developed to determine and identify incurred morantel-related residues in bovine milk by converting them to 3-(3-methyl-2-thienyl) acrylic acid (CP-20,107). Key techniques in this method involve short-term digestion of milk in HC1 to release residues convertible to CP-20,107, isolation and alkaline hydrolysis of these precursors to CP-20,107, and recovery of the product for LC analysis. Photochemical conversion of CP-20,107 to its cisisomer and separation by LC identifies the residue. A homolog (pyrantel), which is used as an internal standard, is hydrolyzed to 3-(2- thienyl) acrylic acid. These acrylic acid isomers are readily resolved by LC. The method was evaluated over the 1-4 ppb (ng/mL) range for accuracy and precision to assess its utility for withdrawal studies. Bovine milk supplemented with morantel at 1,2, and 4 ppb and assayed in replicate (n = 7-8) over 4 trials gave mean values and standard deviations of 1.0 ± 0.11,2.0 ± 0.24, and 4.0 ± 0.44 ppb, respectively. A milk specimen containing physiologically incurred residues of morantel assayed 2.1 ± 0.19 ppb in replicate (n = 5).
Determination of Depletion and Statistical Distribution of Morantel-Related Residues in Bovine Milk Following Administration of Morantel Tartrate to Dairy Cows
Authors: Lynch Martin J , Mosher Franklyn R , Dimmock Mary E , Brunner Linda A , Babcock William E , McManus Robert F , Wheelhouse Robert K 
Published: February 2020

Abstract
Residue depletion studies were conducted in dairy cattle to monitor morantel-related residues in milk following oral administration of morantel tartrate (Rumatel®). Eleven lactating cows of various ages, periods of lactation, and known milk production were orally dosed with the bolus formulation of morantel tartrate with an actual dose range of 8.4-9.8 mg/kg body weight. Representative samples of milk were collected at 10-14 h intervals post-dose, and subsamples were assayed for the major and minor hydrolysis products of morantel-related residues, MAPA and CP-20,107. Residues assayed as precursors of MAPA peaked at the second milking (24 h post-dose) and were below 25 ppb (range: &lt;12-24 ppb). Precursors of CP-20,107, which confirm the identity of morantel, also peaked at 24 h post-dose (range: 2.1-3.3 ppb) and declined rapidly thereafter. A statistical model was used to project the level of residues at the upper limit of 99 % of the total target animal (i.e., dairy cattle) population with 95% confidence. The calculated peak levels from this model were 50 and 5.0 ppb for morantelrelated residues convertible to MAPA and CP-20,107, respectively.
Determination of Cyclopiazonic Acid in Peanuts and Corn by Thin Layer Chromatography
Authors: Lansden John A 
Published: February 2020

Abstract
A thin layer chromatographic system including densitometry has been developed for determining cyclopiazonic acid in peanuts and corn. Samples are extracted with methanol-chloroform (20 + 80); the extract is stripped of most interferences by partitioning with aqueous sodium bicarbonate followed by acidification and repartitioning with chloroform. After thin layer chromatography and derivatization with dimethylaminobenzaldehyde- HCl spray, the toxin is quantitated by reflection densitometry at 540 nm. The recovery of cyclopiazonic acid averages 90% for peanuts and 85% for corn. The absolute detection limit is 25 ng per spot which translates to a detection limit of 125 μg/kg for a 50 g sample.
Extraction and Determination by Gas Chromatography of S,S,S-Tri-n-Butyl Phosphorotrithioate (DEF) in Fish and Water
Authors: Habig Clifford , Nomeir Amin , Digiulio Richard T , Abou-Donia Mohamed B 
Published: February 2020

Abstract
A simple, low-cost, fast method for the extraction and cleanup of DEF (S.S.S-tri-ii-butyl phosphorotrithioate) from fish tissues and water samples was developed. The method combines extraction and cleanup in one step. The basis of the method is passing water samples or aqueous tissue homogenates containing DEF through a C-18 disposable cartridge. DEF is eluted from the cartridge by acetone or ethyl acetate. The eluates are analyzed by gas chromatography using a thermionic-specific detector. The method detects levels as low as 100 parts per trillion (ppt) in water samples; recovery efficiency from spiked fish tissues was greater than 95%. In addition, detectable levels of DEF were recovered from liver, brain, and muscle tissue of fish exposed to this compound. The method has a potential for use with other pesticides.
Isolation and Liquid Chromatographic Determination of the Cyclic Peptide Mycotoxin Cyclosporin A from Rice
Authors: Edwards Judson V , Lillehoj Eivind B 
Published: February 2020

Abstract
A simple method for determination and quantitation of a cyclic peptide mycotoxin, cyclosporin A, in rice is presented. Rice inoculated with Trichoderma polysporum (Link ex Pers.) was extracted with methylene chloride after 4 weeks of incubation. Cyclosporin A was isolated from extracts by using open bed gel filtration column chromatography (LH-20, acetonitrile) and monitored with thin layer chromatography and reverse phase liquid chromatography coelution with a standard. Preliminary thin layer chromatographic methods were developed. Cyclosporin A was detected by iodine and after partial acid hydrolysis by ninhydrin and UV light. A liquid chromatographic method was developed that used a reverse phase disposable cartridge cleanup and isocratic chromatography with a reverse phase octadecylsilica column and a UV detector set at 212 nm. Recovery of cyclosporin A from spiked rice samples (mg/g range) was 85%.
Glucuronidase Assay in a Rapid MPN Determination for Recovery of Escherichia coli from Selected Foods
Authors: Andrews Wallace H , Wilson Clyde R , Poelma Paul L 
Published: February 2020

Abstract
Glucuronidase is present in most strains of Escherichia coli but absent in most other enteric microorganisms; therefore, an assay for this enzyme is useful for determining the presence of the organism. The substrate 4-methylumbelliferyl beta-D-glucuronide (MUG) is incorporated into either lauryl tryptose (LT) broth or EC medium; the inoculated tubes are then incubated under specified conditions and examined under longwave UV light for the presence of a fluorogenic glucuronidase end product. When compared with the 10-day most probable number (MPN) procedure of AOAC, the LT-MUG and the EC-MUG tests required 24 and 96 h, respectively, and gave comparable mean log MPN values for samples of crabmeat, sunflower kernels, and walnut pieces. However, false-positive and falsenegative reactions were observed with foods tested by both of these rapid methods. Overall, method sensitivity was not compromised by using the LT-MUG rather than the EC-MUG method. Incorporation of 25 αg MUG/mL into LT broth resulted in diminished fluorescence of positive reactions, whereas MUG concentrations of 50 and 100 αg/mL provided decisive fluorogenic reactions.
Comparison of Ion-Pair and Ion-Exchange Liquid Chromatography for Assay of Dalapon Products
Authors: Stevens Timothy S , Chritz Karen M 
Published: February 2020

Abstract
The accuracy of the AOAC official first action ion-pair liquid chromatographic assay for dalapon grasskiller products was studied by comparison with an independent ion-exchange liquid chromatographic method. No statistically significant difference in assay results was seen between the latter method and the AOAC official method for the assay of sodium salt, mixed sodium/magnesium salt, or the free acid forms of dalapon.
Determination of N-Nitrosodimethylamine Levels in Some Canadian 2,4-D Amine
Formulations
Authors: Hindle Ralph W , Armstrong J Fred , Peake Adeline A 
Published: February 2020

Abstract
Levels of/V-nitrosodimethylamine (NDMA) were determined in 112 samples of 2,4-dichlorophenoxyacetic acid, (2,4-D), formulated as the dimethylamine salt, collected over a 2 year period from products on the Canadian market. A sample aliquot is partitioned with dichloromethane, and the co-extracted dimethylamine is removed by cleanup on a silica gel column. The eluates containing NDMA are concentrated, an internal standard of /V-nitrosodipropylamine is added, and nitrosamine levels are determined using a gas chromatograph interfaced with a thermal energy analyzer. Recoveries of NDMA and N-nitrosodiethylamine spiked into samples were 103 ± 16 and 96.3 ± 9.8%, respectively. Of the 112 samples analyzed, 92 were below 1 part per million (ppm) relative to the amount of 2,4-D in the samples, 16 were between 1 and 5 ppm, and 4 were greater than 5 ppm. The gas chromatographic column used is compared to a conventional packing material for volatile nitrosamine analysis. Formation of NDMA during cleanup and analysis was shown not to occur.
Liquid Chromatographic Determination of Saccharin in Beverages and Sweets: NMKL Collaborative Study
Authors: Sjoberg Anna-Maija K , Alanko Timo A 
Published: February 2020

Abstract
A reverse phase liquid chromatographic method for the determination of saccharin in a soft drink and a juice was collaboratively studied in 8 laboratories. Collaborators were supplied with 3 samples of the soft drink and 3 samples of the juice containing sodium saccharin levels of 40-100 mg/L. Average recoveries of sodium saccharin were 95.3% for the soft drink and 98.0% for the juice. The reproducibility coefficients of variation were 16.9% for the soft drink and 10.4% for the juice. In addition, a mini-collaborative study was conducted for the determination of saccharin in 3 samples of sweets produced commercially. Five collaborators analyzed the samples, which contained saccharin at levels of 100-600 mg/kg according to the maker's specifications. Saccharin was extracted with water and ethanol and chromatographed using a modified liquid chromatographic method. The reproducibility coefficient of variation was 12.4% for the sweets.
Determination of Total Lipid and Lipid Subclasses in Meat and Meat Products
Authors: Maxwell Robert J 
Published: February 2020

Abstract
Current interest in physiological and nutritional activities of the sterol, polyunsaturated fatty acid, and polar lipid fractions of meats and other foods indicates that analytical methods for lipids should be evaluated on their ability to recover and quantitate these classes. Current methods of lipid isolation furnish an extract that is dependent on the solvent(s) used, the type of food material, the temperature of extraction, and the relative proportions of the lipid classes present. Extraction with ethers or other relatively nonpolar solvents removes principally the neutral fats and nonpolar lipids. For an approximation of the crude fat content, such extraction is often sufficient, because the nonpolar fraction generally constitutes over 90% of the total lipids present. The polar lipids include the biochemically important (ω-3) and (ω-6) polyunsaturated fatty acid classes; thus, the method of lipid extraction of food products becomes relevant for a more complete and valuable characterization of their nutritional value. The various methods of lipid determination for meat products are examined for their total recovery of these important lipid groups. A sequential extraction in conjunction with subsequent analytical methods is recommended.
Thin Layer Chromatographic/Bioautographic Method for Identification of Antibiotic Residues in Animal Tissues
Authors: Neidert Eli , Saschenbrecker Peter W , Tittiger Frank 
Published: February 2020

Abstract
An analytical method for the identification of the residues from 14 commonly used antibiotics is presented. The technique is based on selective tissue extraction followed by thin layer chromatography (TLC)/bioautography. Antibiotic residues are extracted from the tissues with methanol and methanol-HCl (98 + 2). The methanol extract is further extracted with chloroform to isolate groups of antibiotics. The extracts are spotted onto TLC plates and developed in suitable solvent systems. Developed plates are placed on set medium seeded with Bacillus subtilis and a bioautograph is produced. The locations of zones of inhibition are used to identify antibiotic residues. Recoveries of antibiotics were quantitative, while the effect of naturally inhibiting components of the matrix was minimized. The sensitivity of the method can be adjusted through minor modifications, which allows its use in routine regulatory analysis.
Determining Multifumigants in Whole Grains and Legumes, Milled and Low-Fat Grain Products, Spices, Citrus Fruit, and Beverages
Authors: Daft James 
Published: February 2020

Abstract
Whole grain and legumes, milled and low-fat products, spices, citrus fruit, and dry beverage ingredients are leached with purified, acidified acetone-water solutions. Portions of these leachates are then backextracted with purified isooctane. Liquid beverages are directly extracted with the isooctane. Six to 10 nL of each isooctane extract is then screened for 11 fumigant residues by gas chromatography (GC) using electron-capture and Hall electroconductivity detectors, and dual 20% OV-101 columns. Further confirmation of residue identity is done on 20% OV-225/20% OV-17 (2.5 + 1 mixed-bed) and 10% SP-1000 columns. The analytes determined include methyl bromide, methylene chloride, carbon disulfide, chloroform, ethylene dichloride, methyl chloroform, carbon tetrachloride, trichloroethylene, chloropicrin, ethylene dibromide, and tetrachloroethylene, using mixed-component reference solutions. Average recoveries from fortified grain range from 25 to 85%; methyl bromide and chloropicrin were recovered the least. Recoveries from the other kinds of food samples range from 43 to 111%. Advantages of this procedure are (/) clean sample extracts, (2) ppb detection limits, (3) residue stability, (4) relative speed, quality control, and safety of the analysis, and (5) results which gave an accurate picture of residual fumigants in grain and food products.
Multiresidue Method for Determining Substituted Urea Herbicides in Foods by Liquid Chromatography
Authors: Luchtefeld Ronald G. 
Published: February 2020

Abstract
A method is described for determining substituted urea herbicides in foods. The residues are extracted from the product with methanol, and the food coextractives are removed by using solvent partitioning and Florisil column chromatography. The extract is analyzed using liquid chromatography with postcolumn photodegradation, chemical derivatization with orthophthalaldehyde, and spectrofluorometry. Recoveries were determined by spiking 8 different food products with 6 phenylureas—chlorbromuron, chloroxuron, diuron, fluometuron, linuron, and metobromuron—at 0.05 and 0.5 ppm. Three determinations were made at each level for each product. Average recovery at 0.05 ppm was 95% (with a standard deviation of 7.9%), and at 0.5 ppm, 98% (with a standard deviation of 6.9%).
Determination of Nitrogen, Phosphorus, and Potassium in Water-Soluble Fertilizers by Inductively Coupled Plasma Emission Spectrometry
Authors: Nygaard Danton D. , Sotera John J. 
Published: February 2020

Abstract
A modification of an inductively coupled plasma (ICP) emission spectrometer is described that enables the simultaneous determination of nitrogen, phosphorus, and potassium in water-soluble fertilizers. A quartz extension tube is added to the ICP torch to exclude air from the plasma, thus allowing accurate nitrogen determination without adversely affecting sensitivity for other analytes. The modification also requires an 18 mg/L argon coolant flow to protect the tube from the heat of the plasma. Detection limits are 20 mg/L for nitrogen and 50 μg/L for phosphorus and potassium. Three NBS reference salts and 2 commercially available fertilizers were analyzed by the method, and results are in excellent agreement with known values.
Scheme for Validation of an Analytical Protocol: Semiautomated Kjeldahl Nitrogen Determination
Authors: Fisher Murray T , Gurnsey Catherine 
Published: February 2020

Abstract
Definitive validation of an analytical protocol is not always possible. A scheme for performing an alternative type of validation is presented. The scheme is tested on a commonly used chemical procedure for assaying total nitrogen. This alternative validation scheme uses 5 approaches: tests of robustness to recovery of working standards, assay of fortified in-house control materials to assess recovery from typical material, prescribed means of measuring within- and between-batch precision of the assay of typical material, comparison with alternative assay procedures, and determination of analogous certified reference materials to enable calculation of total error. The scheme uses the results of the 5 approaches to obtain a performance profile for the assay. The scheme does not rely on involved statistical modeling or data treatment, yet provides the laboratory worker with a systematic approach to a within-laboratory validation of an analytical protocol.