bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Gas Chromatographic Headspace Determination of Choline in Adult and Infant Formula Products
Authors: Saucerman Janice R , Winstead Charles E , Jones Tom M 
Published: February 2020

Abstract
A gas chromatographic headspace method has been developed for the determination of choline in liquid and powder formula products. Choline undergoes the Hofmann elimination reaction during a 24 h, 120°C alkaline digestion. Volatile trimethylamine (TMA) is produced and equilibrates between the liquid and vapor phase (headspace). A 50 jiL headspace sample is chromatographed on a 28% Pennwalt 223-4% KOH column, with flame ionization detection. Choline is indirectly quantitated by comparing sample TMA peaks with peaks for a reference standard. Ethyl ether is used as an internal standard. Compared with previous methods, this procedure offers improved precision (7.7-9.6% relative standard deviation (RSD)), accuracy, and specificity of both free and bound forms of choline. Estimated analysis rate using manual injection is 160 samples/week, requiring 35 work-hours. Automation of this procedure, using a commercially available headspace analyzer, resulted in a further improvement in precision (1.60-6.91% RSD) and a throughput of 400 samples/week.
Inductively Coupled Plasma Emission Spectroscopic Determination of Nine Elements in Infant Formula: Collaborative Study
Authors: Suddendorf Ronald F , Cook Kathleen K 
Published: February 2020

Abstract
Results from a collaborative study of a method for the determination of 9 elements in infant formula, using inductively coupled plasma emission spectroscopy, are reported. Six collaborators analyzed 6 infant formulas for native and spiked levels of Ca, Cu, Fe, Mg, Mn, P, K, Na, and Zn. The within-laboratory and between-laboratory coefficients of variation were generally (69 of 108 samples) below 9% for all elements determined in all samples. Most of the average recoveries of the elements from spiked samples ranged from 90 to 105%. The method has been adopted official first action for determining Ca, Cu, Fe, Mg, Mn, P, K, Na, and Zn in infant formula.
Liquid Chromatographic Determination of Vitamin B-6 in Foods
Authors: Vanderslice Joseph T , Brownlee Stella R , Cortissoz Mariann E 
Published: February 2020

Abstract
Chromatographic analysis for vitamin B-6 in complex samples imposes certain requirements on the analyst, who must extract completely the bound, unstable vitamers without loss, remove interfering compounds, and provide clean extracts for analysis. The analyst also has to contend with the problems inherent in all methods, such as sample collection, storage, preparation, and homogenization. However, chromatography provides a means of identifying and quantitating all forms of the vitamin, and thus provides the possibility of addressing the problem of the bioavailability of specific vitamers. It also allows automation, which is absolutely essential in coping with the large numbers of samples that are generated in areas such as quality control. These factors are all addressed here, and chromatographic results for various meat and other food products are presented to illustrate the variations in vitamin content that occur from sample to sample, the agreement with microbiological results, and that liquid chromatography (LC) has come of age in dealing with complex biological samples, such as food and food products.
Liquid Chromatographic Determination of Hydroxymethylfurfural in Fruit Juices and Concentrates After Separation on Two Columns
Authors: Cilliers Johannes J L , Van Niekerk Pieter J 
Published: February 2020

Abstract
A liquid chromatographic (LC) method is described for the detection and quantitation of 5-hydroxymethyl-2-furaIdehyde (HMF) in fruit juices and juice concentrates. HMF is separated by chromatography in 2 dimensions with different reverse phase columns. The first column is eluted with aqueous solvents, 5% methanol-2.5% acetonitrile-1.5% tetrahydrofuran (1 + 1 + 1). By using an electrically driven, 6-port valve, the collected impure HMF fraction is rechromatographed on the second column with 5% aqueous methanol as mobile phase. The compound was detected at 284 nm under conditions selected to separate HMF in 26 min with very little or no sample preparation. On a series of samples, this method gave lower values than did the colorimetric toluidine-barbituric acid method.
Gas Chromatographic Determination of Chlorpyrifos Residues in Greenhouse Vegetables After Treatment of Potting Media with Dursban for Imported Fire Ant
Authors: James Joyce P , Spence James H , Ford Joseph H 
Published: February 2020

Abstract
Residues of chlorpyrifos in vegetables were extracted in acetone, and then partitioned between 5% aqueous sodium sulfate solution and hexane to minimize the quantity of oily materials in the extract. Light green vegetable extracts were cleaned up on a silica cartridge, and dark green vegetable extracts were cleaned up with decolorizing carbon and silica gel column chromatography. Chlorpyrifos was determined by gas chromatography (GC) with electron capture detection. The vegetables analyzed were started as seedlings in potting soil treated with Dursban and were transferred to the field for maturation. Residue levels were determined in mature vegetables at the harvestable stage of growth, and ranged from &lt; 0.01 ppm in vegetables, such as cabbage, squash, and tomato, to 0.06 ppm in parsley.
Arsenic, Cadmium, Lead, Mercury, and Selenium in Sediments of Riverine and Pothole Wetlands of the North Central United States
Authors: Martin Dan B , Hartman William A 
Published: February 2020

Abstract
Surface sediments (0-10 cm) collected in 1980 and 1981 from 13 wetland areas in Iowa, Montana, Nebraska, North Dakota, and South Dakota were analyzed for total concentrations of arsenic, cadmium, lead, mercury, and selenium. Sediments from pothole-type wetlands had significantly higher concentrations of arsenic, cadmium, lead, and selenium than those from riverine wetlands. Mean (and range) of dry weight concentrations (mg/kg) for pothole and riverine locations, respectively, were arsenic, 4.4 (1.4-9.3) and 2.4 (0.7-6.1); cadmium, 0.52 (0.17-0.87) and 0.26 (0.01-0.55); lead, 13 (7.4-22) and 6.6 (1.1- 14); selenium, 0.89 (0.13-2.1) and 0.52 (0.03-5.1). Mercury concentrations in sediment did not differ significantly between pothole and riverine type wetlands (mean, 0.03, range, 0.01-0.08). A comparison of the concentrations of elements found in this study with values reported in the literature indicated that, with the possible exception of one location, levels were within normal or background ranges.
Improved Gas Chromatographic Determination of Sorbitan Fatty Acid Esters in Confectionery Products
Authors: Tsuda Taizo , Nakanishi Hiroshi , Kobayashi Shigenobu , Morita Takashi 
Published: February 2020

Abstract
A method is described for gas chromatographic (GC) determination of sorbitan fatty acid esters in confectionery products as sorbitan monostearate. A sample is homogenized with chloroform, filtered, dried, and saponified with 0.1N NaOH in ethanol 1 h at 80°C. The saponification mixture is acidified, washed with hexane, and dried. Isosorbide, 1,4-sorbitan, and D-sorbitol are each derivatized at 70°C with pyridine, hexamethyldisilazane, and trimethylchlorosilane. GC separation of the polyols as TMS (trimethylsilyl) derivatives was performed on a 2% Dexsil 300 column temperature-programmed from 120 to 250°C at 107 min. The sorbitan monostearate content of the sample was calculated from the polyols, using the appropriate conversion factor. The procedure was applied to ice creams, cakes, and other confectionery products. Average recoveries from samples spiked with 1.0% Span 60 (sorbitan monostearate) were 91-96% for isosorbide, 83-99% for 1,4-sorbitan, and 82-98% for D-sorbitol. The detection limit was approximately 0.01%.
Normal Phase Liquid Chromatographic Determination of Sulfamethoxazole in Tablets:
Collaborative Study
Authors: Robinson John W 
Published: February 2020

Abstract
A stability-indicating liquid chromatographic method is presented for determining sulfamethoxazole in tablets. The method uses a 10 p.m silica column, an isooctane-methylene chloride-2-propanol-acetonitrile- glacial acetic acid (70 + 25 + 5 + 5 + 0.5) mobile phase, and photometric detection at 254 nm. Seven laboratories collaboratively studied this method on powdered composite samples prepared from commercial 500 and 1000 mg tablets and on an authentic tablet mixture containing 83.32% added sulfamethoxazole. Mean assay results for the 500 and 1000 mg tablets w ere 102.2 and 97.9% of declared, respectively (n = 4). The mean recovery value for the synthetic sample was 99.4% (n = 4). The pooled reproducibility standard deviation (SD) (coefficient of variation (CV) ) and pooled repeatability SD (CV) were ± 1.01 (1.01%) and ± 0.96 (0.96%), respectively. These results were in good agreement with those obtained by the Associate Referee for the titration method of USP XX. The proposed method can also be used for monitoring the presence of sulfanilamide in sulfamethoxazole by increasing the proportions of both acetonitrile and 2-propanol in the mobile phase. The method has been adopted official first action.
Validation of Liquid Chromatographic Method for Assay of Chlorthalidone in Tablet Formulations
Authors: Fogel Jerry , Sisco Jay , Hess Fritz 
Published: February 2020

Abstract
A stability-indicating, reverse phase liquid chromatographic (LC) method was developed for assay of chlorthalidone in tablet formulations. The chromatographic system separates the parent compound from its potential hydrolysis product (4'-chIoro-3'-sulfamoyl-2-benzophenone carboxylic acid), which can be quantitated at low levels, and another degradation product (2-chloro-5-(l-methoxy-3-oxo-l-isoindolinyl)benzenesulfonamide), which was found during the experimental work. The procedure can also be used for content uniformity determinations. The general utility of the method was demonstrated by the assay of several product brands. The validated procedure was shown to be accurate, precise, reproducible, and specific.
Liquid Chromatographic Method for Identity, Assay, and Content Uniformity of Five Tricyclic Drugs
Authors: Lovering Edward G , Beaulieu Normand , Lawrence Robert C , Sears Roger W 
Published: February 2020

Abstract
A liquid chromatographic (LC) procedure has been developed for the assay, content uniformity, and identification of single active ingredient solid and liquid formulations of amitriptyline, chlorpromazine, imipramine, thioridazine, and trifluoperazine. The drugs are extracted from their formulations with methanol or dilute hydrochloric acid, and identified by comparison of retention times with those of known standards; drugs are quantitated against these standards with rf/-norephedrine hydrochloride as the internal standard. The precision of replicate injections is better than 2.5% for peak area and better than 1% for peak height. The precision of triplicate determinations of tablet composites is better than 2.2%.
Enzyme Immunoassay for Screening Sulfamethazine Residues in Swine Blood
Authors: Fleeker James R , Lovett Leslie J 
Published: February 2020

Abstract
An enzyme immunoassay (EIA) was developed to screen for residues of sulfamethazine (SMT) and its metabolites in swine blood. Swine blood vas treated with perchloric acid and centrifuged. The supernatant solution was neutralized with K2HP04, centrifuged, and applied to a reverse phase Cg cartridge. The analytes were eluted with methanol- water (2 + 3), and the eluate was diluted and assayed. Average recoveries, using 14C-labeled compounds, were 73, 72, 61, and 62% for SMT, W4-glucosyISMT, iV4-acetylSMT, and W4-desaminoSMT, respectively. Tubes coated with antibody were incubated with the eluate and an SMT-P-galactosidase conjugate. Bound enzyme was detected with fluorogenic substrate. When blood was fortified with 0.1 ppm SMT or a molar equivalent of metabolite, the average relative response of the EIA was 100%, control blood; 61%, SMT; 66%, glucosylSMT; 60%, acetylSMT; and 77% desaminoSMT.
Liquid Chromatographic Determination of Narasin in Feed Premixes
Authors: Hussey Raymond L , Macy Thomas D , Moran John , Loh Andrew 
Published: February 2020

Abstract
A liquid chromatographic (LC) method has been developed to determine narasin in feed premixes. Narasin is extracted from the premix with a methanol-water solvent, and the extracted solution is assayed by using LC. Recovery of narasin from a 12.5 g/lb premix is quantitative (100%), with a relative standard deviation of 1.44%. The results correlated well (coefficient 0.92) with a turbimetric bioassay method.
Simple, Rapid Cleanup Method for Analysis of Aflatoxins and Comparison with Various Methods
Authors: Kamimura Hisashi , Nishijima Motohiro , Yasuda Kazuo , Ushiyama Hirofumi , Tabata Setsuko , Matsumoto Sachiko , Nishima Taichiro 
Published: February 2020

Abstract
A method is described for simple and rapid determination of aflatoxins in corn, buckwheat, peanuts, and cheese. Aflatoxins were extracted with chloroform-water and were purified by a Florisil column chromatographic procedure. Column eluates were concentrated and spotted on a high performance thin layer chromatographic (HPTLC) plate, which was then developed in chloroform-acetone (9 + 1) and/or ethermethanol- water (94 + 4.5 + 1.5)orchloroform-isopropanol-acetone (85 + 5 + 10). Each aflatoxin was quantitated by densitometry. The minimum detectable aflatoxin concentrations (μg/kg) in various test materials were 0.2, B1; 0.1, B2; 0.2, G1; 0.1, G2; and 0.1,M1.Recoveries of the aflatoxins added to corn, peanut, and cheese samples at 10-30 μg/kg were &gt; 69% (aflatoxin G2) and averaged 91%, B1; 89%, B2; 91%, G1; 78%, G2; and 92%, M1. The simple method described was compared with the AOAC CB method, AOAC BF method, and AOAC milk and cheese method. These methods were applied to corn, peanut, and cheese composites spiked with known amounts of aflatoxins, and to naturally contaminated buckwheat and cheese. Recoveries were much lower for the BF method compared with our simple method and the CB method.
Comparison of the Volhard and Potentiometric Methods for the Determination of Chloride in Meat Products: Collaborative Study
Authors: Beljaars Paul R , Horwitz William 
Published: February 2020

Abstract
A collaborative study of the determination of chloride in meat products was conducted by the International Organization for Standardization (ISO) to compare the ISO 1841 method (Volhard titration) with the FAO/WHO Codex Alimentarius Committee method (potentiometric titration). Five canned luncheon meat products containing 0.25-2.0% sodium chloride at 4 different spiking levels were analyzed by 11 laboratories. The data were analyzed by ISO statistics (ISO 5725) and by AOAC statistics (Youden-Steiner), the major differences being in the rejection of outliers and in the statement of precision parameters. Good agreement was found between the mean chloride contents of the products as determined by both methods and with the added amounts, although statistically significantly higher sodium chloride recoveries were obtained with the potentiometric method. The within-laboratory variability (repeatability) is greater for the Volhard method, especially for chloride levels below 1.0%. Therefore it is proposed to set the lowest level of determination for the Volhard method at about 1.0% sodium chloride. The among-laboratories variability (reproducibility) of the potentiometric method was comparable with the results from the collaborative studies for chloride in cheese, giving acceptable values for relative standard deviations of 1.5-3.0% for meat products with 0.3-2.0% added sodium chloride. It is recommended that further work be conducted to reduce or eliminate the systematic error present with the potentiometric method as applied to meat and meat
Electrothermal Atomic Absorption Spectroscopic Determination of Chromium in Plant Tissues:
Interlaboratory Study
Authors: Cary Earle E 
Published: February 2020

Abstract
An electrothermal atomic absorption (ETAA) method for determining chromium in plant tissues was collaboratively studied by 6 laboratories. The sample is digested in nitric, perchloric, and sulfuric acids. Chromium is reduced by sodium sulfite and then separated from the digest matrix by coprecipitation with ferric hydroxide. Iron is removed by dissolution and extraction. The remaining silica is dissolved with hydrofluoric acid, and chromium is then determined. After unusually high and low data sets and remaining outliers were rejected, the CV for samples containing 3 μg chromium was 2% but increased to 84% as the chromium concentration in tissue decreased to 0.02 μg/g. The method is recommended for further study.
Dc Polarographic Assay Of Piperazines
Authors: Walash Mohamed I , Rizk Mohamed S , Ibrahim Fawzia A 
Published: February 2020

Abstract
Piperazine, piperazine salts, and piperazine-containing compounds, e.g., diethylcarbamazine and piperazine theophylline, are determined by direct current polarography of the corresponding nitroso-derivative. The nitroso-derivative exhibits a well defined cathodic wave at — 0.8 V vs SCE. The plot of peak height vs concentration is rectilinear between 1.6 x 10"s and 19.2 x 10-5M. Recoveries from bulk drugs were 97.7-101.12% with a standard deviation of 2.14-3.44. The procedure was successfully applied to analysis of drug content in representative dosage forms with good accuracy.
Thin Layer Chromatographic Identification and Quantitation of Niacin and Niacinamide in Pharmaceutical Preparations
Authors: Sarangi Bandita , Chatterjee Sanat K , Dutta Kajal , Das Saroj K 
Published: February 2020

Abstract
A safe and simple thin layer chromatographic method has been developed for the estimation of niacin and niacinamide in pharmaceutical preparations containing other vitamins, enzymes, herbs, antiamoebic drugs, etc. The method involves removal of excipients from the preparation by ethanol precipitation and isolation of niacin or niacinamide from other ingredients by TLC on silica gel with water as developing solvent, followed by extraction in 0.1N HC1, and spectrophotometric estimation of the vitamin at 262 nm. The percent recoveries for niacin and niacinamide were 100.1 ± 1.9 and 100.2 ± 1.5, respectively.
Gas Chromatographic Detection of D-( - )-2,3-Butanediol and Butyric Acid Produced by
Sporeformers in Cream-Style Corn and Canned Beef Noodle Soup: Collaborative Study
Authors: Schafer Mary L , Peeler James T , Bradshaw Joe G , Hamilton Cleo H , Carver Ruth B 
Published: February 2020

Abstract
A gas chromatographic method that identifies sporeformers as the cause of spoilage in swollen cans of low-acid foods was collaboratively studied in 2 stages. Two organic compounds produced by sporeformers, D-( — )-2,3-butanediol and butyric acid, are measured in the upper phase after centrifugation of the liquid portion of the can contents. Each sample is assayed on 2 packed columns designed for the assay of aqueous solutions of volatile fatty acids, using flame ionization detectors. For study 1,16 duplicate inoculated cans of cream-style corn and beef noodle soup were sent to 9 collaborators. For study 2, 7 collaborators received 11 duplicate inoculated cans of the 2 foods. Duplicate uninoculated cans of each food served as negative controls. The inocula were 6 sporeforming organisms (4 Clostridium and 2 gas-forming Bacillus species) and 2 nonsporeformers. After the deletion of marginal samples, the percentages of correctly identified sporeformers and nonsporeformers in beef noodle soup were 83 (110/132) and 90 (54/60), respectively; corresponding percentages for cream-style corn were 80 (98/123) and 100 (35/35). The method has been adopted official first action.
Quantitative Liquid Chromatographic Method Using Fluorescence Detection for Determining Zearalenone and Its Metabolites in Blood Plasma and Urine
Authors: Olsen Monica E , Pettersson Hans I , Sandholm Kerstin A , Kiessling Karl-Heinz C 
Published: February 2020

Abstract
The liquid chromatographic (LC) method described, suitable for use with both blood plasma and urine, is applicable for determination of zearalenone and α-zearalenol at levels as low as 0.5 ng/mL plasma and 5 ng/mL urine. The sample is incubated overnight β with glucuronidase to analyze for both conjugated and unconjugated forms of zearalenone. The next day, the sample is acidified with H3P04, extracted with chloroform, and evaporated to dryness. The residue is dissolved in toluene and loaded onto a silica gel cartridge which is washed with toluene and eluted with toluene-acetone (88 + 12). The eluate is evaporated, and the residue is dissolved in chloroform, extracted with 0.18M NaOH, neutralized with H3PO4, and re-extracted with chloroform. The chloroform extract is evaporated, dissolved in mobile phase for LC, and injected onto a normal phase column under the following chromatographic conditions: mobile phase of water-saturated dichloromethane containing 2% 1-propanol, and fluorescence detector, excitation wavelength 236 nm, and 418 nm cut-off emission filter. Recoveries of zearalenone and its metabolites from blood plasma and urine are 80-89% in the range 2.0-10 ng standard/mL plasma, and 81-90% in the range 10-30 ng standard/mL urine. This method was used to analyze blood and urine samples from a pig fed zearalenone-contaminated feed (5 mg/kg), corresponding to 80 μg/kg body weight. Zearalenone was rapidly metabolized to a-zearalenol, which appeared in the blood only 30 min after feeding. Almost all zearalenone and αzearalenol was found conjugated with glucuronic acid in both blood plasma and urine.
Liquid Chromatographic Determination of Carbadox and Desoxycarbadox in Medicated Feeds and in Porcine Gastrointestinal Tract
Authors: Graaf Gerrit J De , Spierenburg Theodorus J 
Published: February 2020

Abstract
A liquid chromatographic method for the assay of carbadox and desoxycarbadox in medicated feeds and porcine stomach and intestinal contents is described. Samples were extracted with dimethylformamidewater and cleaned up on an alumina column. The eluate was chromatographed using either gradient elution for simultaneous assay of both compounds or isocratic elution for carbadox only. Detection of carbadox by its native fluorescence yielded a sensitive and specific assay without interferences by metabolites or matrix components. The optimal UV absorption of desoxycarbadox was at 280 nm. Mean recoveries of carbadox in spiked feed and stomach contents were 104 and 97%, respectively; mean recovery of desoxycarbadox in stomach contents was 106%. The day-to-day reproducibility for carbadox in different feed samples and stomach contents samples had a coefficient of variation of 6-13%.
Sensitive Enzyme Immunoassay of Colistin and Its Application to Detect Residual Colistin in Rainbow Itout Tissue
Authors: Kitagawa Tsunehiro , Ohtani Wataru , Maeno Yoshiko , Fujiwara Kunio , kimura Yukio 
Published: February 2020

Abstract
An antibody against colistin (CL), an antibiotic effective for gramnegative bacteria, was produced in rabbits immunized with a colistinprotein conjugate. The conjugate was prepared by a novel and convenient procedure devised to couple an amino group of CL to thiol groups of bovine serum albumin (BSA) introduced by thiol exchange reduction of its disulfide bonds with dithiothreitol, using N-(m-maIeimidobenzoyloxy) succinimide (MBS) as a cross-linker. Enzyme labeling of CL with β-D-galactosidase was performed by utilizing another crosslinker, N(γ-maleimidobutyryIoxy)succinimide, by means of a convenient labeling method. A double antibody enzyme immunoassay of CL, which could determine as little as 30 ng/mL of CL, was developed using labeled CL and anti-CL antiserum. With this assay, drug levels were easily determined in fish tissue after CL administration. The enzyme immunoassay should provide a useful tool for detection and quantitation of residual drugs in foods and related products.