bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Six Methods for Determining Aged Phosphine Residues in Wheat
Authors: Allen Sylvia E , Ren Yong-Lin , Desmarchelier James M 
Published: February 2020

abstract
Phosphine (PH3) residues on wheat were determined by gas chromatography (GC) in a blind experiment using 6 methods to assess whether results from different methods are comparable. For one method, 2 different chromatographic conditions also were used. Samples were fumigated for 7 days and aired for 2 or 7 days to obtain "aged" residues. The methods involved determination of PH3 in the headspace over aqueous acidified acetone plus wheat (method a), over ground wheat (method b), over ground wheat plus headspace concentrations over ground wheat in acetone after transfer to another flask (method c), over ground wheat in acetone (method d), over whole wheat after microwave heating (method e), and over water after dilution of 0.5 ml_ aqueous acetone leachate with 10 ml_ buffered sodium sulfate solution (method f). For each method, gas-tight flasks and syringes were used. Data to support new methods c, d, and f are discussed. Each procedure correctly identified the order of PH3 residues as highest, medium, and absent. Quantitative results from all methods were similar, except that results from method b were on average 44% lower than the average results from other procedures. Thus each method, except method b, is suitable for determination of PH3 residues. The relative advantages of each procedure are discussed.
Use of AOAC INTERNATIONAL Method Performance Statistics in the Laboratory
Authors: Lynch Joanna M 
Published: February 2020

abstract
Method performance statistics are included with many AOAC methods and are estimates of precision or variability. These statistics can provide useful guidelines as to the degree of precision that can be achieved when a method is used routinely. Indeed, defining method performance in a practical, meaningful, and standardized way is one of the goals of the AOAC Official Methods program. This paper gives some guidelines for understanding and interpreting AOAC method performance statistics for practical use in the laboratory
Uncertainty—A Chemist's View
Authors: Horwitz William 
Published: February 2020

Abstract
Complete characterization of the performance of analytical methods requires an evaluation of the halo of uncertainty bracketing the reported result. Achieving a satisfactory estimate of this uncertainty is more important than how this estimate is produced. Enumeration of all conceivable error components—the so-called error budget approach— is one way to estimate the uncertainty, but it is not the only way. In fact, when applied to analytical chemistry this approach is likely to (1) overlook important variables and double count others, {2) avoid considering unknown and unknowable interactions and interferences, and {3) adjust for missing variables with an uncontrollable "Type B" component. The problem is one of experimental design. Alternative and more efficient ways of estimating uncertainty in analytical chemistry include the Youden ruggedness procedure, accompanied by a bonus of optimization, and the all-encompassing interlaboratory method-performance trial.
Repeatability and Reproducibility Estimates from Collaborative Studies Based on Total Concentration of Trace Analytes
Authors: Mcclure Foster D 
Published: February 2020

Abstract
In the process of validating a given analytical method for the total concentration of a trace analyte, the precision indicators, repeatability and reproducibility, are obtained from a collaborative study of the method based on a standard one-way completely randomized model. This report discusses the shortcomings of the statistical models used in such studies, defines the component makeup for estimates of the repeatability and reproducibility variances based on these models, and considers suggestions offered as new policy regarding method performance based on total concentration.
Specificity of the BAX Polymerase Chain Reaction System for Detection of the Foodborne Pathogen Listeria monocytogenes
Authors: Stewart Diana , Gendel Steven M 
Published: February 2020

Abstract
The polymerase chain reaction (PCR) can be used for rapid and specific detection of foodborne pathogens. One commercial kit, the Qualicon BAX system uses PCR to detect Listeria monocytogenes in enrichment cultures derived from food and environmental samples. The specificity and sensitivity of the BAX system for detecting L. monocytogenes were characterized by using both pure and mixed cell cultures, and optimal conditions for production of cell lysates were determined. The BAX system was highly specific for L. monocytogenes, and no interference was seen in the presence of either other Listeria species or microbes from other genera. The assay detected L. monocytogenes at 105- 106 colony-forming units/mL. This sensitivity is adequate for detecting viable cells after enrichment but prevents false-positive signals from nonviable cells.
Liquid Chromatographic Determination of Ivermectin in Feed
Authors: Doherty Stephen J , Fox Allen , Fink David W 
Published: February 2020

Abstract
An analytical method for determining ivermectin in feed at 0.50- 3 ppm is presented. The method is based on liquid chromatographic measurement after sample preparation by adsorption chromatography on alumina and solid-phase extraction. Two complete, final, finished medicated feeds and the corresponding control feeds used in their preparation were analyzed. Recoveries from feeds fortified at 50-150% of the 2 ppm ivermectin use concentration also were determined. Mean recoveries from replicate analyses ranged from 90 to 100%, and coefficients of variation (CVs) were less than 4.5%. No significant interferences were found in control feeds. The pooled distribution of individual analytical results (n = 100) gave a mean recovery of 100%, a recovery range of 90-111%, and an overall CV of 5.5%. Resolution of the total variance into its 2 components gave a withinlaboratory CV of 4.1% and a between-laboratory CV of 3.4%. There was no significant difference in recoveries among laboratories, days, concentrations, and feed base or between fortified and medicated feeds (P &gt; 0.2)
Liquid Chromatographic Determination of Five Benzoylurea Insecticides in Fruit and Vegetables
Authors: Gamón Miguel , Saez Adolfo , Pelegrí Rosa , Peris Inmaculada , De La Cuadra Josá G , Coscollá Ramón 
Published: February 2020

Abstract
A liquid chromatographic (LC) method was developed to determine 5 benzoyl ureas—diflubenzuron, hexaflumuron, teflubenzuron, flufenozuron, and lufenuron—in peppers, tomatoes, eggplants, cucumbers, and oranges. Preparation of samples involve extraction with acetone and partitioning into dichloromethane-petroleum ether. A portion of this extract is cleaned up with a solid-phase extraction aminopropyl disposable column. With LC analysis using an RP-8-DB microbore column, acetonitrilewater (70 + 30, v/v) as mobile phase, and photodiode array detection at 254 nm, recovery and repeatability data were collected for the 5 benzoylureas on 4 vegetables and citrus in the range 0.04-2.0 mg/kg. Validated limits of detection and quantitation were 0.01 and 0.04 mg/kg, respectively. The method is reliable for routine analysis of vegetables and fruits
Double Calibration (External Calibration and Stable Isotope Dilution) for Determining Selenium in Plant Tissue by Hydride Generation Inductively Coupled Plasma Mass Spectrometry
Authors: Zhang Ling-Su , Combs Sherry M 
Published: February 2020

Abstract
Both external calibration (EC) and stable isotope dilution (SID) calibration are reliable methods for determining selenium by hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS), but they are rarely used simultaneously. Because these methods are independent of each other, they could be used simultaneously to test each other and to evaluate data quality directly. A double calibration approach using EC and SID simultaneously was developed to evaluate data quality directly for analysis of Se in plant tissue by HG-ICP-MS. Natural Se was used for EC. 77Se-enriched Se (0.004 μg; 77Se = 94.38%) was spiked to 0.5 g sample for SID (78Se or 82Se isotope used as reference isotope). Sample preparation and measurement was not doubled, because one spiked sample served for both EC and SID. All samples were digested with acid and heat, selenate was reduced to selenite, and selenite was measured by HG-ICP-MS. The Se determined by SID corresponded to that determined by EC with a concentration ratio of 1.02 ± 0.08 (n = 207 alfalfa samples). The measured Se in 8 reference materials also agreed well with certified values. The study showed that the double calibration approach was a direct way to evaluate data quality. This approach should be applicable to other multiisotope elements
Assay of Oxytetracycline in Animal Feeds by Liquid Chromatography with Fluorescence Detection
Authors: Houglum Joel E , Larson Richard D , Mutchler Darrel L , Wetzler Luann 
Published: February 2020

Abstract
A liquid chromatographic (LC) method is described to assay oxytetracycline (OTC) in feeds at gram-perton and gram-per-pound levels. Complete feeds and premixes are extracted with acid-methanol, according to AOAC Method 957.23B(i). Extracts are filtered and quantitated by LC using a C18 column and fluorescence detection with excitation at 390 nm and emission at 512 nm. The mobile phase (1.5 mL/min) uses a methanol gradient with an initial hold time of 1 min at 15% methanol followed by an increase to 35% methanol over 8 min. The aqueous component contains CaCI2, disodium ethylenediamine tetraacetate, and sodium acetate buffered to pH 6.5. Recovery of spiked samples averaged 101.6% (coefficients of variation, 0.1- 2.4%), and the limit of detection was 1 g/ton. Results correlated closely with those obtained by using AOAC microbiological Method 968.50 and with another LC method using ultraviolet detection. OTC and epi-OTC elute at approximately 7.4 and 4.8 min, respectively. No interference was observed from several drugs and other antibiotics often used in feeds in combination with OTC
High-Performance Liquid Chromatographic Method for the Determination of Moniliformin in Corn
Authors: Munimbazi Célestin , Bullerman Lloyd B 
Published: February 2020

Abstract
A high-performance liquid chromatographic method using UV absorption was developed for determining moniliformin in corn. The toxin was extracted with water containing 1 % tetrabutylammonium hydrogen sulfate (w/v). Paired moniliformin was partitioned into dichloromethane, which was evaporated to dryness at 50 C. The residue was dissolved in water and applied to a disposable stronganion exchange solid-phase extraction tube. Adsorbed moniliformin was eluted from the tube with 0.05M sodium dihydrogen phosphate monohydrate (pH 5). It was determined by ion-pair reversed-phase chromatography and UV measurement at 229 nm. The minimum detectable amount of pure moniliformin was 0.25 ng/injection (signal-to-noise ratio = 3:1). The detector response was linear from 0.25 to at least 20 ng. The limit of determination was 0.025 μg/g corn. Recoveries of moniliformin from corn spiked at 0.025,0.05,0.25, and 1.0 μg/g averaged 96.5,96.2, 97.2, and 97.8% respectively
Performance Tested Method Certification of BAX™ for Screening/Salmonella: A Case Study
Authors: Mrozinski Peter M , Betts Roy p , Coates Scott 
Published: February 2020

Abstract
This report details the independent laboratory study of the BAX™® for Screening/Salmonella assay to complete AOAC Performance Tested Method certification. The performance of the BAX system was compared with those of BAM culture methods on food samples inoculated with Salmonella. This study validated product claims. Performance Tested Method status was granted for the screening assay.
Liquid Chromatographic Determination of Sugar Alcohols in Beverages and Foods after Nitrobenzoylation
Authors: Nojiri Shuko , Saito Kazuo , Taguchi Nobuo , Oishi Mitsuo , Maki Toshio 
Published: February 2020

Abstract
Use of p-nitrobenzoyl chloride (PNBC) to form an ultraviolet-absorbing derivative was attempted to determine the sugar alcohols meso-erythritol, xyli-tol, D-sorbitol,and D-mannitol by liquid chromatography (LC). LC determination of derivatives was performed on an ODS column with acetonitrile–water (65 + 35) as mobile phase. Calibration curves were linear in the concentration range 0.01–100 μg/mL. Method sensitivity is 10 to 1000 times higher than that of LC with refractive index detection and gas chromatography with flame ionization detection. Recoveries of sugars added to various foods at 0.1 and 1% ranged from 91 to 102% for meso-erythritol, 75 to 115% for xylitol, 81 to 105% for D-sorbitol, and 81 to 108% for D-mannitol.
Determination of Submicrogram-per-Liter Concentrations of Caffeine in Surface Water and Groundwater Samples by Solid-Phase Extraction and Liquid Chromatography
Authors: Burkhardt Mark R , Soliven Paul P , Werner Stephen L , Vaught Deborah G 
Published: February 2020

Abstract
A method for determining submicrogram-per-liter concentrations of caffeine in surface water and groundwater samples has been developed. Caffeine is extracted from a 1 L water sample with a 0.5 g graphitized carbon-based solid-phase cartridge, eluted with methylene chloride-methanol (80 + 20, v/v), and analyzed by liquid chromatography with photodiode-array detection. The single-operator method detection limit for organic-free water samples was 0.02 μg/L. Mean recoveries and relative standard deviations were 93 ± 13% for organic- free water samples fortified at 0.04 μg/L and 84 ± 4% for laboratory reagent spikes fortified at 0.5 μg/L. Environmental concentrations of caffeine ranged from 0.003 to 1.44 μg/L in surface water samples and from 0.01 to 0.08 μg/L in groundwater samples.
Analysis of a Mixture of Polychlorinated Biphenyls and Chlorinated Pesticides in Human Serum by Column Fractionation and Dual-Column Capillary Gas Chromatography with Electron Capture Detection
Authors: Najam Allah R , Korver Margaret P , Williams Cynthia C , Burse Virlyn W , Needham Larry L 
Published: February 2020

Abstract
An analytical method is presented for precise identification and quantitation of 29 specific polychlorinated biphenyl (PCB) congeners and 15 chlorinated pesticides in human serum. Analyte surrogates PCB 30, PCB 204, 2,2′,4,4′,5,5′-hexa-bromo-biphenyl, perthane, α-hexachiorocyclohexane, and dichlorobenzophenone were added to each sample. The serum was extracted with an organic solvent and separated by adsorption chromatography into 3 elution fractions for high-resolution gas chromatographic analysis. Each fraction was analyzed by dual-column capillary chromatography followed by electron capture detection. Two capillary columns, DB-5 and DB-1701, with different polarities were used to increase selectivity for each analyte. Quantitation was performed by selecting 2 sets of calibration standard mixtures and 1,2-di-chloronaphthalene as an internal standard. Mean recoveries ranged from 39 to 126% for selected analytes and from 31 to 88% for surrogates. Detection limits for specific congeners and pesticides are reported. Typical chromatographic profiles of calibration standard mixtures, as well as a human sample, are illustrated. Verification of each analyte is assessed, and results of analyses of selected human samples and quality control criteria used to ensure data validity also are presented.
Recent Advances in Thin-Layer Chromatography of Pesticides
Authors: Sherma Joseph 
Published: February 2020

Abstract
Advances in the use of thin-layer chromatography (TLC) and high-performance TLC (HPTLC) for separation, detection, and qualitative and quantitative determination of pesticides, other agrochemicals, and related compounds are reviewed for the period 1996–1998. Analyses are covered for avariety of food, biological, and environmental samples and for residues of various pesticides, including insecticides, herbicides, and fungicides, belonging to different chemical classes. References on formulation analysis, hydrophobicity studies, and use of TLC and thin-layer radiochromatography for studies of pesticide metabolism, degradation, uptake, and related studies also are included.
Determination of Oxytetracycline, Tetracycline, and Chlortetracycline in Milk by Liquid Chromatography with Postcolumn Derivatization and Fluorescence Detection
Authors: Pena Angelina L S , Lino Celeste M , Silveira Irene N 
Published: February 2020

Abstract
A multiresidue method for isolation and liquid chromatographic determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) in milk is presented. The sensitivity of the method is adequate to meet the needs of regulatory agencies. The European Community established 100 μg/kg as the maximum residue limit (MRL) in milk for TC, CTC, and OTC. Recoveries exceeded 80% for all tetracyclines at all levels, with good precision. Correlation coefficients of standards curves for individual tetracyclines isolated from fortified samples ranged from 0.991 for CTC to 0.998 for OTC. Other antibiotics that might interfere with analysis did notinterfere with elution times of OTC, TC, andCTC. The procedure is rapid, precise, and quantitative and requires minimal preparation andminimal use of organic solvents. It can beapplied to routine surveillance programs. We canprepare 10 samples for analysis in about 1.45 h.
Determination and Survey of Ochratoxin A in Wheat, Barley, and Coffee—1997
Authors: Trucksess Mary W , Giler John , Young Kathryn , White Kevin D , Page Samuel W 
Published: February 2020

Abstract
Ochratoxin A (OA) is a nephrotoxic and nephrocarcinogenic mycotoxin produced by Aspergillus and Penicillium species. It has been found mainly in cereal grains and coffee beans. The purpose of this study was to investigate the occurrence of OA in cereal grains and in coffee imported to the United States. A modified liquid chromatographic (LC) method for determining OA in green coffee was applied to wheat, barley, green coffee, and roasted coffee. The test sample was extracted with methanol–1% NaHCO3 (7 + 3), and the extract was filtered. The filtrate was diluted with phosphate-buffered saline (PBS), filtered, and passed through an immunoaffinity column. After the column was washed with PBS and then with water, OA was eluted with methanol. The eluate was evaporated to dryness, and the residue was dissolved in acetonitrile–water (1 +1). OA was separated on a reversed-phase C18 LC column with acetonitrile-water-acetic acid (55 + 45 + 1) as eluant and quantitated with a fluorescence detector. Recoveries of OA from the 4 commodities spiked over the range 1–4 ng/g were 71–96%. The limit of detection was about 0.03 ng/g. OA contamination at &gt;0.03 ng/g was found in 56 of 383 wheat samples, 11 of 103 barley samples, 9 of 19 green coffee samples, and 9 of 13 roasted coffee samples. None of the coffee samples contained OA at &gt;5 ng/g; only 4 samples of wheat and 1 sample of barley were contaminated above this level.
Inulin and Oligofructose Are Part of the Dietary Fiber Complex
Authors: Prosky Leon 
Published: February 2020

Abstract
Dietary fiber has been defined as the remnants of plant cells resistant to hydrolysis by human alimentary enzymes. Its main chemical constituents are hemicelluloses, celluloses, lignin, pectins, gums, and waxes. The U.S. Food and Drug Administration and the U.S. Department of Agriculture determine compliance with nutritional labeling regulations for dietary fiber by use of the existing AOAC INTERNATIONAL methods for total dietary fiber. The above compounds are readily detected by these methods. However, some oligo and polysaccharides are resistant to human alimentary enzymes and do not precipitate in 78% ethanol, the usual reagent for precipitating dietary fiber in analytical procedures. Some of these saccharides, termed fructans, are inulin and oligofructose. They possess many physiological attributes normally associated with dietary fiber. Inulin is a mixture of oligo and polysaccharides composed of fructose moieties joined by β(2→1) linkages in linear chains. Almost each chain ends with a glucose moiety. Oligofructose is a synonym for fructooligosaccharides, with fructose moieties joined by β(2→1) linkages, as in inulin. Not all molecules have a glucose unit, and the chain length is less than 10 units. A method for inulin and oligofructose was developed andapproved official first action by AOAC INTERNATIONAL in early 1997. It involves extraction of sample and treatment of the extract with amyloglucosidase followed by fructozyme (Fructozyme™ Enzyme Process Division, Novo Nordisk, Novo Industry, Copenhagen, Denmark). The sugars released in each of the 3 steps are measured by anion-exchange chromatography. The concentration of fructans is calculated as the difference of sugars, glucose and fructose, after the enzymatic treatments and the initial sample. The repeatability standard deviations for inulin and oligofructose ranged from 2.9 to 5.8% and the reproducibility standard deviations ranged
Separation of C60 and C70 Fullerenes by Thin-Layer Chromatography on Silica Gel Impregnated with Polymers
Authors: Litvinova Larissa S , Zgonnik Vladimir N 
Published: February 2020

Abstract
Separation of C60 and C7 fullerenes was studied on silica gel layers impregnated with polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), and poly(ethyl- ene oxide) (PEO) solutions at 0.5-2.5%. To evaluate the effect of polymer nature on the retention of fullerenes, ΔhRf’ values were determined: ΔhRf’ =hRf(impregnated siO2)-hRf(siO2). For all polymers, the ΔhRf’ values of fullerenes increased with increasing concentration (C) of the impregnating solution. At C = 2.5%, ΔhRf’ increased with polymer nature in the following order: PVA &lt; PEO &lt; PVP. The separation selectivity of fullerenes also improved. Increasing the concentration of acetate groups in PVA increased ΔhRf’. The nature of interaction between fullerene and polymers is discussed.
Assay of Tinidazole in Human Serum by High-Performance Thin-Layer Chromatography—Comparison with High-Performance Liquid Chromatography
Authors: Guermouche M H , Habel D , Guermouche S 
Published: February 2020

Abstract
Determination of tinidazole in human serum by high-performance thin-layer chromatography (HPTLC) is presented. It includes use of 10 × 10 cm plates coated with silica gel 60 and chloroform-acetonitrile-acetic acid (60 + 40 + 2) as mobile phase. Quantitation was performed by densitometry at 320 nm. The linearity (1-10 ng), precision (6%), reproducibility (5%), recovery (96%), and detection limit (1 mg/L) of tinidazole determination by HPTLC were comparable with corresponding method parameters by reversed-phase HPLC. A satisfactory correlation was found between the 2 analytical methods. The procedure was used to quantitate tinidazole in patient sera.
Analysis of All-Rac-α-Tocopheryl Acetate and Retinyl Palmitate in Medical Foods Using a Zero Control Reference Material (ZRM) as a Method Development Tool
Authors: William Chase G , Eitenmiller Ronald R , Long Austin R 
Published: February 2020

Abstract
A liquid chromatographic method is described for analysis of all-rac-α-tocopheryl acetate and retinyl palmitate in medical food. The vitamins are extracted in isopropyl alcohol and hexane-ethyl acetate without saponification and quantitated by normal-phase chromatography with fluorescence detection. All-rac-α-tocopheryl acetate and retinyl palmitate are chromatographed isocratically with a mobile phase of 0.5% (v/v) and 0.125% (v/v) isopropyl alcohol in hexane, respectively. Recovery studies performed on a medical food zero control reference material (ZRM) fortified with the analytes averaged 99.7% (n = 25) for retinyl palmitate and 101% (n = 25) for all-rac-α-tocopheryl acetate. Coefficients of variation were 0.87-2.63% for retinyl palmitate and 1.42-3.20% for all-rac-α-tocopheryl acetate. The method provides a rapid, specific, and easily controlled assay for analysis of vitamin A and vitamin E in medical foods. Use of chlorinated solvents is avoided.