bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid Chromatographic Determination of Vitamin K1 in Infant Formulas and Milk
Authors: Indyk Harvey E , Littlejohn Vernon C , Lawrence Richard J , Woollard David C 
Published: February 2020

Abstract
Vitamin K1 in infant formulas and milk products is determined by reversed-phase liquid chromatography (LC) with UV detection. The sample is hydrolyzed enzymatically, and the vitamin is extracted with hexane. Fractionation by normal-phase semipreparative LC is followed by analytical LC, with quantitation by the internal standard technique. Recovery of the analyte was 97.4 ± 2.8%. Linearity was established between 0.05 and 4.0 fig/mL. The limit of quantitation is 0.5 μg/100 g for milk powder, which allows the method to quantitate endogenous levels of vitamin K1.
Determination of Fat, Protein, and Total Solids in Cheese by Near-Infrared Reflectance Spectroscopy
Authors: Rodriguez-Otero José Louis , Hermida Maria , Cepeda Alberto 
Published: February 2020

Abstract
Near-infrared reflectance (NIR) spectroscopy was used to analyze fat, protein, and total solids in cheese without any sample treatment. A set of 92 samples of cow’s milk cheese was used for instrument calibration by principal components analysis and modified partial least-square regression. The following statistical values were obtained: standard error of calibration (SEC) = 0.388 and squared correlation coefficient (R2) = 0.99 for fat, SEC = 0.397 and R2 = 0.98 for protein, and SEC = 0.412 and R2 = 0.99 for total solids. To validate the calibration, an independent set of 25 cheese samples of the same type was used. Standard errors of validation were 0.47,0.50, and 0.61 for fat, protein, and total solids, respectively, and hf for the regression of measurements by reference methods versus measurements by NIR spectroscopy was 0.98 for the 3 components.
Determination of Thiabendazole in Potatoes, Fruits, and Their Processed Products by Liquid Chromatography
Authors: Bushway Rodney J , Li Lei , Paradis Lance R , Perkins Lewis B 
Published: February 2020

Abstract
A liquid chromatographic method has been developed for analysis of the fungicide thiabendazole (TBZ) in fruits, potatoes, and their processed products. Extraction was performed in a 50 mL polyethylene conical centrifuge tube with a basic solution. TBZ was partitioned (into methylene chloride with a polytron. No further cleanup was needed. Separation was carried out on a 5 μm Ultracarb 30 ODS column with fluorescent detection, excitation at 305 nm and emission at 345 nm. Total analysis time including extraction was 25 min per sample. Recoveries ranged from 77 to 135%. Average percent recovery for all sample types spiked from 5 ppb to 387 ppm was 94% with a coefficient of variation (CV) of 11%. Overall intra-assay CVs varied from 1.8 to 23%, and interassay CVs ranged from 1.8 to 15%. Of 194 commercial samples analyzed for TBZ, 129 were positive. TBZ in positive samples ranged from 1.1 ppb to 72.5 ppm. The limit of quantitation varied from 2.5 ppb for juices, 2.5 ppb for fruits and potatoes, and 4.5 ppb for bulk concentrates. Detection limits were 1.0 ppb for juice, fruits, and potatoes and 2 ppb for bulk concentrates. TBZ levels in the positive samples were corroborated by immunoassay.
Liquid Chromatographic Determination of Bromide Ion in Cereals, Fruit, Vegetables, and Blood with a Silver Electrode in an Electrochemical Detector System
Authors: Lindgren Bertil , Berglöf Tomas , Ramberg Åsa , Stepdmska Anna , Åkerblom Malin 
Published: February 2020

Abstract
A method is presented for rapid determination of bromide ion in commodities and blood by paired-ion liquid chromatography with electrochemical detection. The method involves extraction of samples with water and filtration. Blood is passed through a Sep-Pak C18 minicolumn. Recoveries are usually close to 100%, with satisfactory precision. The detection limit is 1 mg/kg. The method needs little labor and uses no noxious solvents or reagents.
Liquid Chromatographic Determination of Simazine, Atrazine, and Propazine Residues in Catfish
Authors: Holland David C , Munns Robert K , Roybal José E , Hurlbut Jeffrey A , Long Austin R 
Published: February 2020

Abstract
A liquid chromatographic (LC) method is described for the simultaneous determination of the triazine herbicides, simazine (SIM), atrazine (ATZ), and propazine (PRO) in the 12.5–100 ppb range in catfish. The herbicides are extracted from catfish homogenates with ethyl acetate, followed by solvent partitioning between acetonitrile and petroleum ether and additional cleanup on a C18 cartridge. A Supelcosil LC-18-DB column is used for LC separation, and UV determination is at 220 nm. The isocratic mobile phase is a mixture of methanol, acetonitrile, and water. Mean recoveries from catfish were 88.7, 96.9, and 91.7%; standard deviations were 6.84,7.78, and 6.26%; and coefficients of variation were 7.72,8.03, and 6.82% for SIM, ATZ, and PRO, respectively.
Liquid Chromatographic Determination of Furazolidone in Swine Serum and Avian Egg
Authors: Yosheda Kenichi , Kondo Fusao 
Published: February 2020

Abstract
A rapid, simple, and accurate method for determination of furazolidone (FZ) in swine serum and avian egg using liquid chromatography (LC) with a 358 nm ultraviolet-visible spectrophotometric detector is described. After liquid–liquid extraction of sample with ethyl acetate using Extrelut-3, the extract is evaporated, redissolved in 40% acetonitrile, and injected directly into the chromatograph. The antibiotic can be analyzed within 30 min. Withinday recoveries for swine serum and avian egg spiked with FZ at 1 ppm were 90.0 and 88.1%, respectively, with coefficients of variation of 3.52 and 3.88%, respectively. Between days recoveries for the 1 ppm samples were 87.2 and 87.0%, with coefficients of variation of 3.10 and 4.29%, respectively. Determination of FZ also was performed by LC/mass spectrometry (MS) with an atmosphericpressure chemical-ionization interface (APCI) system. The LC/MS–APCI system is more applicable for qualitative analysis than quantitative analysis because the drug detection limit (about 0.1 μg/mL) is almost the same as that of the LC–UV detector.
Estimation of Azadirachtin-A Content of Emulsifiable and Solution Concentrates of Neem
Authors: Azam Mohibb E , Rengasamy Seem , Parmar Balraj S 
Published: February 2020

Abstract
A column chromatographic cleanup method to remove aliphatic and aromatic solvent components and different surfactants present in formulated neem was developed. A glass column containing silica gel (60–120 British Standard Sieve) and 250 mL hexane–acetone (6 + 4) was used. Impurities interfering in the region of the azadirachtin-A peak were removed by fractional elution. Recovery of azadirachtin-A was greater than 81%.
U.S. Food and Drug Administration Pesticide Program: Incidence/Level Monitoring of Domestic and Imported Pears and Tomatoes
Authors: Roy Ronald R , Albert Richard H , Wilson Patrick , Laski Ronald R , Roberts James I , Hoffmann Terry J , Bong Rodney L , Bohannon Byron O , Yess Norma J 
Published: February 2020

Abstract
In 1992–1993, the U.S. Food and Drug Administration (FDA) conducted a statistically based study of pesticide residues in domestic and imported pears and tomatoes. For pears, 710 domestic and 949 imported samples were collected and analyzed; 79% of the domestic and 72% of the imported samples had detectable residues. Thiabendazole, a fungicide with postharvest uses, was found with greatest frequency in both groups of pears. Four domestic and 12 imported samples contained violative residues, mainly of pesticides for which there are no U.S. tolerances on pears. The statistically weighted (by shipment size) violation rates for domestic and imported pears were 1.0 and 0.9%, respectively. For tomatoes, 1219 domestic and 144 imported samples were collected and analyzed; 84% of the domestic and 91% of the imported samples had detectable residues. Methamidophos, an insecticide, had the greatest frequency of occurrence in both groups of tomatoes. Thirtythree domestic and 5 imported samples were violative, nearly all the result of acephate use, for which there is no U.S. tolerance on tomatoes. The statistically weighted violation rates for domestic and imported tomatoes were 1.9 and 7.0%, respectively. The statistically weighted violation rates calculated for domestic and imported pears and domestic tomatoes in this study were lower than those observed under FDA’s regulatory monitoring in recent years. The violation rate for imported tomatoes was somewhat higher under statistical monitoring than under regulatory monitoring. The results of the statistically based study show that, as in regulatory monitoring, the levels of pesticide residues found are generally well below U.S. tolerances.
Daily Intakes of THbutyltin and THphenyltin Compounds from Meals
Authors: Tsuda Taizo , Inoue Tomohiro , Kojima Mihoko , Aoki Shigeru 
Published: February 2020

Abstract
Daily intakes of tributyltin (TBT) and triphenyltin (TPT) compounds from meals in Shiga Prefecture, Japan, were investigated by 2 methods. Daily intakes of TBT and TPT by the duplicate portion method were, respectively, 4.7 and 0.7 μg in 1991 and 2.2 and 0.7 μg in 1992. Those by the market basket method were, respectively, 6.9 and 5.4 μg in 1991 and 6.7 and 1.3 μg in 1992. Daily intakes of TBT and TPT by the market basket method were higher than those by the duplicate portion method. These values were considerably lower than acceptable daily intakes of 80 μg/50 kg body weight specified by the Welfare Ministry of Japan for bis(tri-n-butyltin) oxide and of 25 μg/50 kg body weight specified by the Food and Agriculture Organization/ World Health Organization for TPT.
Cryopreservation of Bacterial Vegetative Cells Used in Antibiotic Assay
Authors: Reamer Richard , Dey B R , Thaker Nitin 
Published: February 2020

Abstract
A long-term cryopreservation study of vegetative cells of Micrococcus lutea ATCC 9341a, Micrococcus lutea ATCC 15957, and Staphylococcus epidermidis ATCC 12228 cells, used in our antibiotic bioassay procedure, was conducted. The cryoprotective abilities of 1% methylcellulose solution and a 15% glycerol solution at −14°C were determined. More organisms remained viable in 1% methylcellulose than in 15% glycerol. Overall survival of Staphylococcus epidermidis ATCC 12228 after 365 days was 1.5 logs lower than the other 2 organisms. The sensitivity and the resistance of the preserved organisms to various antibiotics did not change: The methodology is simple and inexpensive, saves analytical time, and avoids risk of contamination and sudden loss of a well-characterized culture.
Planar Chromatography for Screening of Ivermectin Residues in Swine and Cattle Tissues
Authors: Abjean Jean-Pierre , Gaugain Murielle 
Published: February 2020

Abstract
A method was developed for qualitative detection of ivermectin residues. It involves extraction of 1 g tissue sample with 5 mL acetonitrile and C18 solid-phase extraction. After derivatization with tri-fluoroacetic anhydride, the extract is purified again on the same but previously reconditioned C18 column. The eluate is evaporated, and the residue is diluted in methanol. The method allows detection of residues in swine and cattle meat, liver, and fat at levels as low as 5 μg/kg.
Effects of Drying Temperature on Fumonisin Recovery From Feeds
Authors: Bordson Gary O , Meerdink Gavin L , Bauer Karla J , Tumbleson Mike E 
Published: February 2020

Abstract
A number of corn and feed samples submitted for fumonisin analysis contain high levels of moisture. The high moisture content can interfere with grinding during sample preparation and, if samples are held at room temperature, may promote fungal, bacterial, and/or other microbial growth. To inhibit possible sample deterioration, wet corn and feed samples routinely are stored in a freezer. Prior to grinding, the sample, or a representative portion, is dried. Using a fumonisin-positive, rain-soaked, pelleted mixed feed, we found that prolonged drying at temperatures above 50°C results in decreased fumonisin recoveries. Therefore, we carried out a study to assess the effect of drying times and temperatures on recoveries of fumonisins FB1 and FB2. A fumonisin-positive corn sample and the pelleted mixed feed were dried for various periods up to 24 h at 30°, 50°, or 110°C. Duplicate samples were dried for 0, 0.25, 0.5, 1, 2, 4, 8, or 24 h at each temperature. Samples were extracted with solvent, and an aliquot of each extract was cleaned up with Cie Sep-Pak cartridges. Extracts were derivatized with fluorescamine and analyzed by liquid chromatography with fluorescence detection. During the 24 h drying period, recoveries of fumonisins FB1 and FB2 from samples dried at 110°C exhibited a nonlinear decrease. Recoveries from samples dried at 30° and 50°C showed no real change.
Potentiometric Determination of Cyanoguanidine and Analysis of Its Unique Titration Curve
Authors: Yoshevaga Tetsutaro , Koga Masaaki , Kawano Kentaro 
Published: February 2020

Abstract
Cyanoguanidine (CG) is an important starting or intermediate material for many synthetic compounds and is useful as a fertilizer. Calcium cyanamide (CaCN2 fertilizer easily hydrolyzes to cyanamide (NH2CN; Cy), and Cy dimerizes into CG under weakly alkaline condition. In the present work, CG was determined potentiometrically with a silver sulfide membrane-type ion-selective electrode. A unique titration curve was obtained when a sample solution of CG and picrate (or picric acid) at a picrate/CG molar ratio of 1.5 or more was titrated with silver nitrate standard solution. The curve showed a rapid potential drop at half-equivalence point, and by using this point, accurate and precise values of CG were obtained (recovery, 99.8%; relative standard deviation, 0.1%, n = 10). Even at a wide pH range (1.7 to 10.2), CG was determined accurately. The presence of Cy scarcely interfered. CG (400 μmol) was detected with a molar ratio of 190. With the standard addition method, CG (400 μmol) was determined even with a Cy/CG molar ratio of 2500. The lowest detection limit was 4 × 10−3 mol/L (40 μmol absolute).
Determination of Tetracycline Residues in Bovine Milk, Serum, and Urine by Capillary Electrophoresis
Authors: Chen Chao-Ling , Gu Xuelin 
Published: February 2020

Abstract
A method was developed for simultaneous determination of oxytetracycline (OTC), chlortetracycline, tetracycline, and doxycycline levels in cow milk, serum, and urine by capillary electrophoresis (CE). The tetracyclines (TCs) were extracted specifically with a metal-chelating affinity column. Extracts were then applied to C18 cartridges treated with dimethyldichlorosilane, and the TCs were eluted with ethanol. Salt-free sample residues were run on CE with a diode array detector at 370 nm. A 50 cm × 75 μm uncoated capillary at 15 kV and 23°C was used to separate the TCs. The run buffer contained 10 mM sodium dodecyl sulfate, 50 mM borate, and 50 mM phosphate, pH 8.5. TC peaks were identified by migration times, coinjection of standards, and diode array spectra. Limits of detection for TCs were 1.3-5.3 ng/mL, and limits of quantitation were 1.7-8.7 ng/mL in cow fluid samples. OTC appeared consistently at 13.3-13.4 min in milk, serum, and urine samples from a cow treated with OTC. OTC was further identified by coinjection of OTC standard and OTC diode array spectra. The CE method can be used to simultaneously determine 4 TC residues at low parts-per-billion levels.
Modification of AOAC Multiresidue Method for Determination of Synthetic Pyrethroid Residues in Fruits, Vegetables, and Grains. Part I: Acetonitrile Extraction System and Optimization of Florisil Cleanup and Gas Chromatography
Authors: Pang Guo-Fang , Chao Yan-Zhong , Fan Chun-Lin , Zhang Jin-Jie , Li Xue-Min , Zhao Tie-Sheng 
Published: February 2020

Abstract
We present a multiresidue method for determination of synthetic pyrethroids in fruits, vegetables, and grains. The method is a modification of AOAC Method 970.52. Residues are extracted with acetonitrile (for fruits and vegetables) or acetonitrile–water (2 + 1) (for grains) and then transferred to hexane. Coextractives are removed by acetonitrile partitioning and open-column chromatography with deactivated Florisil. The final extract is analyzed by gas chromatography with electron capture detection (GC–ECD). An HP-17 wide-bore column is used to determine the total isomeric content of each insecticide, and a DB-5 narrow-bore column is used to determine the individual isomeric contents of each insecticide. The method was used to recover 8 pyrethroids (biphenthrin, fenpropathrin, cyhalothrin, permethrin, cypermethrin, fluvalinate, fenvalerate, and deltamethrin) spiked at 0.01–4.0 mg/kg in 20 crops (apple, pear, peach, banana, grape, strawberry, potato, tomato, cucumber, pepper, cabbage, carrot, celery, polished rice, wheat, green gram, buckwheat, sorghum, maize, and barley). Recoveries of the 8 pyrethroid insecticides in 6 crops ranged from 83.8 to 112.8%, with a coefficient of variation (CV) of 2.00 to 12.09% for the narrow- bore capillary GC (n = 6) and from 82.8 to 106.4%, CV = 2.93–12.19%, for the wide-bore capillary GC (n = 6). The minimum detectable levels of 0.004–0.028 mg/kg (for fruits and vegetables) or 0.01–0.08 mg/kg (for grains) for the 8 pyrethroids are easy to detect.
Determination of Chromium and Molybdenum in Medical Foods by Graphite Furnace Atomic Absorption Spectrophotometry
Authors: Phifer Edwin C 
Published: February 2020

Abstract
Graphite furnace atomic absorption spectrophotometry was used to determine chromium and molybdenum in 7 medical foods from 5 manufacturers. Linear standard curves were obtained for both elements for concentrations between 5 and 25 ng/mL. Detection limits were 0.24 ng/mL for Cr and 0.67 ng/mL for Mo. Characteristic masses were 3.1 and 14.7 pg for Cr and Mo, respectively. No difference was detected between wet and dry ashing methods, and dry ashing was used to complete the study. The method was validated by assaying various National Institute of Standards and Technology standard reference materials. Analysis of these products for Cr and Mo were within certified values. One product was evaluated by this method for reproducibility (n = 5). Relative standard deviations were 6.8 and 4.8% for Cr and Mo, respectively. This product contained 0.31 ± 0.02 μg Cr/g and 0.63 ± 0.03 μg Mo/g. The remaining products contained 0.09–1.28 μg Cr/g and 0.07–2.3 μg Mo/g. Mean recovery values were 98 ± 14% (n = 14) for Cr at spike levels of 0.20–1.89 μg/g and 102 ± 24% (n = 10) for Mo at spike levels of 0.30–1.89 μg/g.
Determination of Glyphosate and Its Metabolite, (Aminomethyl)phosphonic Acid, in River Water
Authors: Mogadati Paul S , Louis Judith B , Rosen Joseph D 
Published: February 2020

Abstract
A procedure for extracting glyphosate and its meta bolite, (aminomethyl)phosphonic acid, from river water and for determining these 2 compounds by gas chromatography/ion trap mass spectrometry is described. Both compounds were extracted with Bio-Rad AG 1-X8 anion-exchange resin (formate form) prior to derivatization with a mixture of trifluoroacetic anhydride and trifluoroethanol. Limits of detection for glyphosate and its metabolite were 1 ppb even when as little as 10 mL water was analyzed. Recoveries of both compounds from river water fortified at 50 ppb were &gt;90%.
Determination of Dietary Fiber and Carbohydrate Composition of Foods by a Modified Version of the Englyst Method
Authors: Lichon Michael J , James Keith W 
Published: February 2020

Abstract
A modified version of the Englyst procedure for determination of dietary fiber and carbohydrate fractions of foods is described. The method is based on hydrolysis of separated fractions and capillary gas chromatographic (GC) analysis of derivatized monomer sugars, UV photometry of uronic acids, gravimetric determination of residue, and analysis of nitrogen content of the residue by using a C, H,N elemental analyzer. Modifications of fractiona tion, derivatization, and GC procedures are dis cussed. Rigorous sample preparation is required for reproducibility of 200 mg test portions. Contami nants interfering with chromatography must be minimized. Results for reference samples (wheat bran and Buerre Bose pears) and white and wholemeal bread agree with literature values.
Monitoring of Pesticide Residues in Fresh Vegetables, Fruits, and Other Selected Food Items in Belgium, 1991-1993
Authors: Dejonckheere Willy , Steurbaut Walter , Drieghe Sabine , Verstraeten Roland , Braeckman Hans 
Published: February 2020

Abstract
To estimate the exposure of the Belgian population to food contaminated with pesticide residues andto determine what pesticides people are actually consuming, a total diet study—individual approach—was performed. Fourteen kinds of fruits, 22 kinds of vegetables, and 7 other food items (coffee, drinking water, rice, tea, wine, bran, and wheat flour) were selected as major representatives of the Belgian diet. During the 2 years of study (April 1991- March 1993), about 3698 samples were analyzed and 21 163 analyses were performed. The first part of this study demonstrates that no residues are found in 31.3% of leafy vegetables, 72.3% of other vegetables, 51.4% of fruits, and 67.2% of other samples. In particular cases, some critical situations still exist, especially for leafy vegetables. Also, contamination of foreign samples is not easy to determine, because origins are not always traceable.
Method Development in Supercritical Fluid Extraction
Authors: McNally Mary Ellen P 
Published: February 2020

Abstract
When using supercritical fluid extraction (SFE), a variety of chemical and physical parameter interactions must be considered in developing a sample preparation method. Those interactions, especially for an analyst who is unfamiliar with the properties and potentials of supercritical fluids, can make routine analytical method development quite rigorous. This paper is meant as a guide for a novice user of SFE. It illustrates a logical scheme to consider when removing an analyte from a difficult matrix.
Robotic Automated Analysis of Foods for Aflatoxin
Authors: Carman Allen S , Kuan Shia S , Ware George M , Umrigar Pesi P , Miller Kenneth V , Guerrero Humberto G 
Published: February 2020

Abstract
Immunoaffinity column-based sample preparation procedures for determination of aflatoxins B1, B2,G1, and G2 in several food matrixes and aflatoxin M1 in milk have been automated by using flexible automation, or robotics. Components used to assemble the system were purchased commercially or developed and built in-house. A liquid-level sensor developed in-house to assist elution of the immunoaffinity column is described. After immunoaf finity column cleanup, aflatoxins are separated by reversed-phase liquid chromatography and determined by fluorescence without derivatization.Mean recoveries of aflatoxins B1, B2, and G1 added to corn and nuts at 9-36 ng/g total aflatoxins were &gt;85% (coefficient of variation [CV] = 16%). Recoveries of aflatoxin G2 averaged 50% (CV = 28%). Recoveries of aflatoxin M1 added to milk at 0.120.50 ng/mL averaged 78% (CV = 19%). The ability of the automated system to reproduce its results is demonstrated by the fact that the CV of replicate assays is generally better than 10%. Comparability between the automated procedure and the AOAC official method is demonstrated.