bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid Chromatographic Determination of Triasulfuron in Soil
Authors: Gennari Mara , Ferraris Lucia , Nègre Michèle , Cignetti Alessandro 
Published: February 2020

Abstract
Two extraction methods were developed for the determination of triasulfuron in soil. Method I included extraction with methanol–phosphate buffer at pH 7 (2 + 1, v/v), liquid–liquid partition with dichloromethane, and cleanup on a liquid chromatographic Si adsorption solid-phase extraction tube. In Method II, Extrelut was added and the sample was then extracted with acetonitrile. In both cases, the extracts were analyzed by liquid chromatography (LC) with UV detection and the LC peak was confirmed by LC/mass spectrometry (MS). The 2 methods were tested on 3 soils having different physicochemical characteristics. Method I gave 83% average recovery and a determination limit of 0.4 μg/kg soil. Method II gave 67% average recovery and a determination limit of 2 μg/kg soil. Examples of application of Method I to field samples are reported.
Enumeration of Cryptosporidium spp. in Water with U.S. EPA Method 1622
Authors: Sinclair James L 
Published: February 2020

Abstract
The occurrence of Cryptosporidium parvum or other pathogenic Cryptosporidium species in water must be known in order to assess risk and determine the treatment needed to reduce Cryptosporidium oocysts to acceptable levels in finished drinking water. Because Cryptosporidium oocyst occurrence may be sparse, methods must concentrate a large volume of water and correctly identify oocysts in the concentrate. The U.S. Environmental Protection Agency Information Collection Rule (ICR) protozoan method gives low and variable recoveries of Cryptosporidium oocysts, making risk assessment difficult. Therefore, a method giving better oocyst recovery and more consistent results was needed. Method 1622 was developed with existing materials and procedures, and improvements were made in filtration, cleanup, and detection. Absolute porosity filters were used, with cleanup by immunomagnetic separation and detection by direct fluorescent antibody stain with 4′,6-diamidino-2-phenylindole (DAPI) staining for additional cell structures. Both the level and consistency of oocyst recovery were improved compared to recovery with the ICR method.
Determination of Sulfite in Oriental Herbal Medicines
Authors: Kim Young-Kyung , Koh Eunmi , Park Sang-Yong , Chang Seung-Yeup , Park Soo-Jin , Na Won-Il , Kim Hie-Joon 
Published: February 2020

Abstract
Sulfite was detected in 7 varieties of Oriental herbal medicines (Pueraria radix, Zingiberis rhizoma, Platycodon radix, Adenophora radix, Pinellia tuber, Astragalus radix, and Paeonia radix) on the Korean market. Sulfiting of commercial Oriental herbal medicines by fumigation with burning bituminous coal was simulated, and the accumulation of sulfite was investigated by using fresh Platycodon radix roots obtained from a growing field. The sulfite level reached a plateau in 9 h, and the maximum sulfite level found by the Monier-Williams (MW) method (AOAC 990.28) was 1020 ppm. The sulfite content in the simulated Platycodon radix sample determined by alkali extraction followed by ion-exclusion chromatography with electrochemical detection (AOAC 990.31) was approximately 17% lower on average than the MW results. Free-sulfite levels determined by acid extraction and ion-exclusion chromatography with electrochemical detection were between 19 and 49% of the MW results. The advantages of different methods for sulfite determination and the significance of the results are discussed.
Determination of Fluvalinate Residues in Beeswax by Gas Chromatography with Electron-Capture Detection
Authors: Tsigouri Angeliki , Menkissoglu-Spiroudi Urania , Thrasyvoulou Andreas T , Diamantidis Grigorios C 
Published: February 2020

Abstract
A simple, rapid, and accurate method is described for the determination of residual fluvalinate in beeswax. The procedure consists of partitioning on a disposable column of diatomaceous earth (Extrelut®), followed by chromatographic cleanup on a Florisil cartridge. The final extract is analyzed by capillary gas chromatography with electron-capture detection (GC–ECD). Briefly, wax samples were dissolved in n-hexane, and the solutions were sonicated and transferred to Extrelut columns. The fluvalinate was extracted with acetonitrile, and a portion of the extract was cleaned up on a Florisil cartridge. The fluvalinate was eluted with diethyl ether–n-hexane (1 + 1) and directly determined by GC–ECD. Recoveries from wax samples spiked at 5 fortification levels (100–1500 μg/kg) ranged from 77.4 to 87.3%, with coefficients of variation of 5.12–8.31%. The overall recovery of the method was 81.4 ± 3.2%, and the limit of determination was 100 μg/kg.
Sampling, Sample Preparation, and Analytical Variability Associated with Testing Wheat for Deoxynivalenol
Authors: Whitaker Thomas B , Hagler Winston M , Giesbrecht Francis G , Johansson Anders S 
Published: February 2020

Abstract
The variability associated with testing wheat for deoxynivalenol (DON) was measured using a 0.454 kg sample, Romer mill, 25 g comminuted subsample, and the Romer Fluoroquant analytical method. The total variability was partitioned into sampling, sample preparation, and analytical variability components. Each variance component was a function of the DON concentration and equations were developed to predict each variance component using regression techniques. The effect of sample size, subsample size, and number of aliquots on reducing the variability of the DON test procedure was also determined. For the test procedure, the coefficient of variation (CV) associated with testing wheat at 5 ppm was 13.4%. The CVs associated with sampling, sample preparation, and analysis were 6.3, 10.0, and 6.3%, respectively. For the sample variation, a 0.454 kg sample was used; for the sample preparation variation, a Romer mill and a 25 g subsample were used; for the analytical variation, the Romer Fluoroquant method was used. The CVs associated with testing wheat are relatively small compared to the CV associated with testing other commodities for other mycotoxins, such as aflatoxin in peanuts. Even when the small sample size of 0.454 kg was used, the sampling variation was not the largest source of error as found in other mycotoxin test procedures.
Recovery of Atrazine, Bromacil, Chlorpyrifos, and Metolachlor from Water Samples after Concentration on Solid-Phase Extraction Disks: Interlaboratory Study
Authors: Mueller Thomas C , Senseman Scott A , Wauchope R Don , Clegg Chris , Young Roddy W , Southwick Lloyd M , Riley Melissa B , Moye H Anson , Dumas Jose A , Mersie Wondi , Mattice John D , Leidy Ross B 
Published: February 2020

Abstract
An interlaboratory comparison was conducted in 1997 and 1998 to examine the feasibility of using C18 solid-phase extraction disks (Empore™) to simultaneously determine the herbicides atrazine, bromacil, and metolachlor and the insecticide chlorpyrifos in water samples. A common fortification source and sample processing procedure were used to minimize variation in initial concentrations and operator inconsistencies. The protocol consisted of paired laboratories in different locations coordinating their activities and shipping fortified water samples (deionized or local surface water) or Empore disks on which the pesticides had been retained and then quantitating the analytes by a variety of gas chromatographic methods. Average recoveries from all laboratories were &gt;80% for atrazine, bromacil, and metolachlor, and &gt;70% for chlorpyrifos. Detection of bromacil was unachievable at some locations because of chromatographic problems. Shipping samples between cooperating laboratories did not affect the recovery of atrazine, chlorpyrifos, or metolachlor in either matrix. Recoveries tended to be higher from disks shipped to cooperating laboratories compared with those from fortified water. Shipping disks eliminated many problems associated with the shipment of water samples, such as bottle breakage, higher shipping cost, and possible pesticide degradation. Recoveries of bromacil and metolachlor were lower from fortified surface water samples than from fortified deionized water samples. This collaborative research demonstrated that pesticides in water samples can be concentrated on solid-phase extraction disks at one location and quantitated under diverse analytical conditions at another location. The extraction efficiencies of the disks were comparable with or better than the recoveries obtained from the shipped water samples, and the problems associated with shipping water samples were eliminated by using the disks.
Use of Fuzzy Regression for Calibration in Thin-Layer Chromatography/Densitometry
Authors: Sârbu Costel 
Published: February 2020

Abstract
A new fuzzy regression algorithm was successfully applied to calibration in thin-layer chromatography (TLC)/densitometry. Different regression techniques were also considered, and objective quality coefficients were used for evaluation of the results. Depending on the structure of the data, the fuzzy procedure can improve the results dramatically. From the results reported in this paper and other unpublished results, it appears clear that the calibration procedure based on fuzzy regression is the most suitable regression method in quantitative TLC.
Simultaneous Determination of Amoxycillin Trihydrate and Clavulanate Potassium in Pharmaceutical Preparations by Thin-Layer Chromatography/Densitometry
Authors: Indrayanto Gunawan , Sa Tan Kiauw , Widjaja Sonja 
Published: February 2020

Abstract
A simple and rapid densitometric method has been developed for the simultaneous determination of amoxycillin trihydrate and clavulanate potassium in pharmaceutical preparations. After extraction of the analytes with distilled water, the extracts were spotted on precoated silica gel plates, which were then eluted with butyl acetate–methanol–glacial acetic acid–water (15 + 7.5 + 7.5 + 3, v/v). Quantitative evaluation was performed by measuring the absorbance reflectance of the analyte spots at λ = 240 nm. The densitometric method is rapid, selective, precise, and accurate and, thus, can be used for routine analysis of pharmaceutical preparations in quality control laboratories of the pharmaceutical industry.
Determination of Halofuginone and Amprolium in Chicken Muscle and Egg by Liquid Chromatography
Authors: Yamamoto Yuzo , Kondo Fusao 
Published: February 2020

Abstract
A liquid chromatographic (LC) method was developed for simultaneous measurement of halofuginone (HFN) and amprolium (APL) in chicken muscle and egg. HFN and APL were extracted from chicken muscle and egg with acetonitrile. In chicken egg, they were partially purified by solid-phase extraction (SPE) to separate them from impurities. The LC separation was performed on a 4.6 mm id × 250 mm TSK-gel ODS-80TM column using acetonitrile–McIlvaine buffer, pH 3.4, containing 0.01M sodium lauryl sulfate (42 + 58) as the mobile phase. Ultraviolet detection of HFN and APL was performed at wavelengths of 242 and 265 nm, respectively. Recoveries of HFN and APL from chicken muscle spiked at 0.5 μg/g were 74.8 ± 17.7 and 94.2 ± 5.0%, respectively (mean ± standard deviation [SD], n = 10). In chicken muscle, the lower limit of determination for both APL and HFN was 0.03 μg/g. Recoveries of HFN and APL from chicken egg spiked at 0.5 μg/g by a cleanup procedure using SPE were 54.6 ± 3.4 and 85.0 ± 2.4%, respectively (mean ± SD, n = 5). In chicken egg, the lower limit of determination for both APL and HFN was 0.04 μg/g.
Comparison of Amplified ELISA and Mouse Bioassay Procedures for Determination of Botulinal Toxins A, B, E, and F
Authors: Ferreira Joseph L 
Published: February 2020

Abstract
The amplified enzyme-linked immunosorbent assay (amp-ELISA) was compared to the mouse bioassay for determination of botulinal neurotoxin types A, B, E, and F. Twelve different toxin-producing type A, 13 proteolytic type B, 9 nonproteolytic type B, 16 type E, 8 proteolytic type F, 5 nonproteolytic type F, and 6 nontoxigenic clostridial strains were tested. The cultures were inoculated into cooked meat medium (CMM) and tryptone-peptone-glucose-yeast extract (TPGY) medium, incubated for 5 days, and then examined for biological toxicity in mice and amp-ELISA endpoints. The amp-ELISA was less sensitive in detecting toxins produced by nonproteolytic than proteolytic strains of type B and F organisms. All of the toxin-producing strains tested were positive by the AOAC method and the amp-ELISA in either undiluted TPGY or CMM culture fluids regardless of mouse toxicity level, source, or strain. Cross-reactivity was observed between some but not all of the botulinal strains tested. None of the nontoxigenic strains were positive by the amp-ELISA. Purified botulinal toxins were also assayed using these 2 methods. The sensitivity of the amp-ELISA using purified neurotoxins was about 0.1 ng/mL for types A, B, and E and about 1.0 ng/mL for type F.
Comparison of Methods for Extraction of Tobacco Alkaloids
Authors: Jones Nadiá M , Bernardo-Gil M Gabriela , Lourenco M Graço 
Published: February 2020

Abstract
Ultrasound and microwave techniques were used to extract tobacco alkaloids, and response surface methodology was used to optimize extraction conditions. Ultrasonic technique factors were temperature, 30–85°C; time, 3–45 min; solvent volume, 8–80 mL. Microwave extraction factors were pressure, 15–75 psi; time, 3–40 min; power, 30–90% of the maximum magnetron power of 650 W. Soxhlet and solvent AOAC-modified extraction methods were also applied after some improvements. Nicotine, nornicotine, anabasine, and anatabine were quantified by gas chromatography. A steam distillation International Standards Organization method for total alkaloid evaluation was used as reference. The results obtained by the different methods were compared using a least squares deviation test. The ultrasonic and the proposed modified-AOAC extraction method were the more convenient with regard to practicability and precision. The relative deviations (n = 5) were as follows: For the ultrasonic method in low-level alkaloid tobaccos, 0.7% nicotine and 1.4–14% minor alkaloids; in high-level alkaloid tobaccos, 2.4% nicotine and 4.5–5.1% minor alkaloids. For the modified AOAC method in low-level alkaloid tobaccos, 0.9% nicotine and 2.4–11.6% minor alkaloids; and in high-level alkaloid tobaccos, 1.7% nicotine and 2.0–2.4% minor alkaloids.
Determination of Acetochlor in Technical and Formulated Products by Capillary Gas Chromatography
Authors: Kahn Bobbi B , Tomkins David F 
Published: February 2020

Abstract
A peer-verified gas chromatographic (GC) method is presented for the weight percent (wt %) determination of acetochlor herbicide in technical and formulated products. During method development, the method was found to be rugged by the Youden Ruggedness Test. Two laboratories with experience in the wt % determination of acetochlor in various matrixes participated in this study. Each laboratory received 10 blind duplicate test samples of the following 5 matrixes: one acetochlor technical and 4, different, emulsifiable concentrate (EC) formulations—Harness® EC (MON 5841), Harness ® Export/Fist (MON 8435), Surpass® EC (HF), and Surpass ® EC (LF). Each participant was asked to make duplicate weighings of each of the test samples and to inject each test sample solution twice. All test samples were analyzed on the same day, and 8 data points (replicates) per matrix were obtained. The test samples were dissolved in acetone that contained dipentyl phthalate as an internal standard. They were analyzed by GC on a 15 m capillary column by using split injection and a flame ionization detector. Acetochlor (wt %) was determined by comparing the ratios of peak area of acetochlor/peak area of dipentyl phthalate internal standard obtained for the test sample and calibration solutions. Repeatability of the method, expressed as the within-laboratory (between replicates) relative standard deviation (RSDr), was found to be 0.09–0.77% for the 5 matrixes. Reproducibility of the method, expressed as the within-test sample relative standard deviation (RSDR), was found to be 0.18–0.78% for the 5 matrixes.
Visible Spectrophotometric Determination of Tantalum in Soil, Sediment, Minerals, and Alloys
Authors: Patel Khageshwar Singh , Shukla Aditya , Agarwal Neeta , Hoffmann Peter 
Published: February 2020

Abstract
A new, sensitive, and selective method is described for the spectrophotometric determination of Ta(V). The method is based on the extraction of the Ta(V)–F−–CV+ complex (CV+ = crystal violet cation) with a benzene solution of imidoyl derivatives (ID), i.e., N,N′-diphenylbenzamidine (DPBA), N-hydroxy- N,N′-diphenylbenzamidine, and N-(2,5-dimethyl)phenyl-p-tolylimidoylphenylhydrazine, from sulfuric acid solution; DPBA was selected for detailed study. The molar absorptivities of the Ta(V)–F−–CV+–ID complexes in the benzene solution were in the range of (1.00–1.65) × 105 L/mol·cm at 600 nm. The limit of detection was 7 ng Ta/mL (which had an absorbance greater than that of the blank + 3 standard deviations). The optimization of the analytical variables, the composition of the complex, and the effect of diverse ions in the determination of Ta are discussed. The present method was applied to the determination of Ta in environmental samples, i.e., soil, sediment, minerals, and alloys.
Determination of Sucrose Esters of Fatty Acids in Food Additive Premixes by Gas Chromatography and Confirmation of Identity by Gas Chromatography/Mass Spectrometry
Authors: Uematsu Yoko , Hirata Keiko , Suzuki Kumi , Iida Kenji , Kan Teruo , Saito Kazuo 
Published: February 2020

Abstract
A gas chromatographic (GC) method was developed for the determination of sucrose monoesters of fatty acids (mono-SuE) and sucrose acetate isobutyrate (SAIB) in food additive premixes. Mono-SuE and SAIB fractions were prepared by column chromatography with either a C8 or a silica gel solid-phase extraction column. The mono-SuE fraction was acetylated and applied to a wide-bore GC column (0.53 mm × 15 m) by splitless injection for determination. The SAIB fraction was applied to the GC column without derivatization. Gas chromatography/mass spectrometry was used to confirm the identity of GC peaks. The detection limits for mono-SuE and SAIB were 0.005 and 0.01%, respectively. Mono-SuE (C12, C14, C16, C18, and C18:1) and SAIB were found in commercial food additive premixes and some foods.
Simultaneous Determination of Imazalil and Its Major Metabolite in Citrus Fruit by Solid-Phase Extraction and Capillary Gas Chromatography with Electron Capture Detection
Authors: Matsumoto Hisashi 
Published: February 2020

Abstract
A method was developed for the simultaneous determination of imazalil and its major metabolite, R 14821, in citrus fruit. This method (designated the SPE method) is based on solid-phase extraction (SPE) and capillary gas chromatography (GC) with electron-capture detection (ECD). The SPE method is highly sensitive for both compounds (limit of detection for each: 0.001 μg/g) and is less time consuming than the previously reported method based on repeated liquid–liquid partitioning and GC–ECD. Recoveries for 3 levels of fortification (0.02, 0.2, and 2.5 μg/g) from satsuma mandarins ranged from 94.3 to 96.5% for imazalil and from 93.9 to 96.3% for R 14821, with coefficients of variation (CVs) ranging from 3.1 to 6.3% for imazalil and from 4.5 to 5.6% for R 14821. Average residual levels found in grapefruit, oranges, and lemons by the SPE method and the previously reported method, and the corresponding CVs, were similar.
Occurrence of 1,4-Dioxane in Cosmetic Raw Materials and Finished Cosmetic Products
Authors: Black Roderick E , Hurley Fred J , Havery Donald C 
Published: February 2020

Abstract
Surveys of cosmetic raw materials and finished products for the presence of the carcinogen 1,4-dioxane have been conducted by the U.S. Food and Drug Administration since 1979. Analytical methods are described for the determination of 1,4-dioxane in ethoxylated cosmetic raw materials and cosmetic finished products. 1,4-Dioxane was isolated by azeotropic atmospheric distillation and determined by gas chromatography using n-butanol as an internal standard. A solid-phase extraction procedure based on a previously published method for the determination of 1,4-dioxane in cosmetic finished products was also used. 1,4-Dioxane was found in ethoxylated raw materials at levels up to 1410 ppm, and at levels up to 279 ppm in cosmetic finished products. Levels of 1,4-dioxane in excess of 85 ppm in children's shampoos indicate that continued monitoring of raw materials and finished products is warranted.
Determination of Niacin in Infant Formula by Solid-Phase Extraction and Anion-Exchange Liquid Chromatography
Authors: LaCroix Denis E , Wolf Wayne R , Porter Eural , Cantellops Dennis , Chase G William , Woollard David 
Published: February 2020

Abstract
A peer-verified, solid-phase extraction (SPE)/anion exchange liquid chromatographic method is presented for the determination of niacin in milk-based and soy-based infant formula. Analysis is in 3 steps: test sample digestion, extraction/cleanup, and liquid chromatography (LC). Digestion uses a standard AOAC digestion procedure that involves autoclaving at 121°C for 45 min in (1 + 1) H2SO4 to free endogenous niacin from protein and to convert added niacinamide to niacin. The digest solution is adjusted to pH 6.5 with 7.5M NaOH. Acidification to pH &lt;1.0 with (1 + 1) H2SO4 precipitates the protein. The clarified solution is then filtered, and the filtrate is brought to volume. SPE of niacin is accomplished by passing an aliquot of the digest solution through an aromatic sulfonic acid–SPE (ArSCX–SPE) column. After the column is washed with methanol and water to remove extraneous material, the niacin is eluted with 0.25M sodium acetate/acetic acid buffer at pH 5.6. An anion-exchange polystyrene–divinylbenzene column with 0.1M sodium acetate/acetic acid buffer at pH 4.0 is used for LC. Niacin is determined by UV detection at 260 nm. A standard curve is prepared by passing known amounts of niacin through the ArSCX–SPE columns used for niacin extraction. The following values for x_bar and relative standard deviation (RSD) were obtained for National Institute of Standards and Technology Standard Reference Material (NIST SRM) 1846 Infant Formula with a certified value for niacin of 63.3 ± 7.6 μg/g: Submitting laboratory.— x_bar = 59.7 ± 4.0 μg/g; RSD = &gt;6.7%; confidence interval (CI) = ± 1.4 μg/g; n = 27. Peer laboratory.— x_bar = 56.6 ± 6.6 μg/g; RSD = &gt;11.7%; CI = ± 4.1 μg/g; n = 8.
Determination of Phenolic Disinfectant Agents in Commercial Formulations by Liquid Chromatography
Authors: Thompson Richard D 
Published: February 2020

Abstract
Using liquid chromatography (LC), a convenient and versatile method was developed for the assay of disinfectant products containing the commonly used phenolic agents, alone or in combination, including phenol, 2-phenylphenol, 4-t-amylphenol, 4-chloro-3,5-dimethylphenol (PCMX), 2-benzyl-4-chlorophenol, and triclosan. The procedure involves a simple dilution or dissolution of the product aliquot or portion followed by membrane filtration and LC. The method was applied to 19 different products representing 17 manufacturers and containing from one to 4 phenolic agents. Chromatography was performed using a Zorbax SB-C18 column, acetonitrile–0.05M KH2PO4 (55 + 45, v/v) pH 3.00, as mobile phase and UV detection at 280 nm. The intralaboratory precision of the product assays ranged form 0.34–5.35% (n = 5) and recoveries via fortification varied from 96.1–103.8%. The limits of quantitation (LOQ) and detection (LOD) ranged from 5.58 × 10−5 to 2.50 × 10−4 mg/mL and from 1.76 × 10−5 to 0.67 × 10−4 mg/mL, respectively, for the 6 analytes. The response for all analytes was observed to be linear for at least a 50-fold range in concentration (0.001–0.05 mg/mL). The proposed method provides an efficient means for the isolation and quantitation of these phenolic compounds.