bluuebunny/crossref_metadata_2025_split huggingface dataset:
Procedures for Estimating Confidence Intervals for Selected Method Performance Parameters
Authors: McClure Foster D , Lee Jung-Keun 
Published: February 2020

Abstract
Procedures for estimating confidence intervals (CIs) for the repeatability variance (σr2), reproducibility variance (σR2 = σL2 + σr2), laboratory component (σL2), and their corresponding standard deviations σr, σR, and σL, respectively, are presented. In addition, CIs for the ratio of the repeatability component to the reproducibility variance (σr2/σR2) and the ratio of the laboratory component to the reproducibility variance (σL2/σR2) are also presented.
Synergy between Liquid Chromatographic–Pulsed Amperometric Detection and Capillary-Gas Chromatographic Methods for the Detection of Juice Adulteration
Authors: Hammond David A 
Published: February 2020

Abstract
The use of liquid chromatography linked with pulsed amperometric detection, and capillary-gas chromatography to detect the adulteration of fruit juices is discussed. These are 2 complementary approaches which can be used to detect the addition of sugar syrups to juices at low levels.
Routine Analysis of Ascorbic Acid in Citrus Juice Using Capillary Electrophoresis
Authors: Cancalon Paul F 
Published: February 2020

Abstract
A procedure to monitor citrus juice samples was established to quantitate vitamin C by capillary electrophoresis using a previously developed method. Dilution and filtration were the only preparation requirements and separation was achieved with an uncoated capillary using a 35mM sodium borate buffer (pH 9.3) containing 5% (v/v) acetonitrile at 21 kV and 23°C. Detection was performed by high speed scanning between 200 and 360 nm. From the multiwave length scan, the electropherogram at 270 nm was extracted and used to quantitate ascorbic acid. The ascorbic acid concentration was calculated with an internal standard method, with ferulic acid as internal standard. The level of ascorbic acid during analysis was stabilized with ethylenediaminetetraacetic acid and dithiothreitol was used to reduce dehydroascorbic acid to ascorbic acid to estimate the total vitamin C level. Results were similar to those obtained by liquid chromatography and the method is now used to determine routinely the level of ascorbic acid in citrus juices.
Stability and Recovery of Triazine and Chloroacetamide Herbicides from pH Adjusted Water Samples by Using Empore Solid-Phase Extraction Disks and Gas Chromatography with Ion Trap Mass Spectrometry
Authors: Mueller Thomas C , Senseman Scott A , Carson Kathy H , Sciumbato Audie S 
Published: February 2020

Abstract
Empore disks were used to successfully extract herbicide residues from a difficult-to-analyze surface water source and deionized water. Herbicide recoveries were lower in surface water at 7, 14, or 21 days after fortification and storage at 4°C, presumably due to chemical sorption onto precipitated organic particulates. The addition of acid to the samples, as recommended in EPA Method 525.2, did not affect recoveries of alachlor and metolachlor, but reduced recoveries of atrazine, simazine, and cyanazine. Treatment of water samples with sodium hypochlorite did not affect alachlor or metolachlor recoveries, but greatly reduced the recovery of all triazine herbicides. This indicates that addition of acid or sodium hypochlorite to water samples may be detrimental to triazine analysis.
Multiresidue Determination of Pesticides in Fruit and Vegetables by Gas Chromatography/Tandem Mass Spectrometry
Authors: Gamón Miguel , Lleó Concha , Ten Amparo , Mocholí Francisco 
Published: February 2020

Abstract
Pesticide residues in fruit and vegetables were determined by gas chromatography/tandem mass spectrometry (GC/MS/MS). Electron impact (EI)/MS/MS and chemical ionization (CI)/MS/MS were developed for 80 compounds, including organochlorine, organophosphorus, organonitrogen, and pyrethroids, providing unambiguous spectral confirmation for these complex matrixes. Residues were extracted from samples with acetone followed by a mixture of dichloromethane–petroleum ether. Two injections per sample were required for analysis of the entire pesticide list by EI/MS/MS and CI/MS/MS.Initial steps involving cleanup and concentration of extracts were eliminated. The excellent selectivity and good linearity allowed quantification and identification of low levels of pesticides in the most difficult matrixes. The method has been used for routine analysis of many vegetables.
Plasma Analysis of Celiprolol by HPTLC: A Useful Technique for Pharmacokinetic Studies
Authors: Savale Hema S , Pandya Kalpesh K , Gandhi Thakorbhai P , Modi Indravadan A , Modi Rajiv I , Satia Milan C 
Published: February 2020

Abstract
A rapid and sensitive high performance, thin-layer chromatographic (HPTLC) method has been developed for the measurement of celiprolol in human plasma and its use in pharmacokinetic studies has been evaluated. Detection and quantitation were performed without using an internal standard. A simple extraction procedure was followed for extracting celiprolol from plasma and a known amount of the extract was spotted on precoated silica gel 60 F254 plates using a Camag Linomat IV autosampler. Celiprolol was quantitated using a Camag TLC Scanner 3. The average recovery of authentic analytes (20 to 200 ng/mL) added to plasma was 72.06 ± 2.8% and the lowest amount of celiprolol that could be detected was 10 ng/mL. The method provides a direct estimate of the amount of celiprolol present in plasma. Pharmacokinetic parameters of 2 marketed preparations have also been determined after oral administration to 12 healthy human volunteers.
TLC Determination of Mebendazol and Pentoxifylline as Residues on Pharmaceutical Equipment Surfaces
Authors: Vovk Irena , Simonovska Breda 
Published: February 2020

Abstract
This paper presents the applicability of thin-layer chromatographic methods with a subsequent densitometric or video densitometric quantitation for determination of residues in controlling pharmaceutical equipment cleanliness. Analytical methods were developed for monitoring residues of pentoxifylline at 10 mg/m2 and mebendazol at 1 mg/m2 on stainless steel surfaces. Simulated samples were prepared by addition of a calculated amount of pharmaceutical (as a solution) on a 35 × 35 cm stainless steel surface. After evaporation of solvent, the residues were wiped with wetted cotton. The cotton was extracted with dichloromethan–methanol (1 + 1). Filtered extract was concentrated by vacuum evaporation and an aliquot applied to the plate, where standards were also applied. In the narrow concentration range near the acceptable residue limits, linear calibration curve could be obtained for both substances. The mean recovery (n = 4) obtained by densitometric quantitation was 93.4% for pentoxifylline and 85.6% for mebendazol, with coefficients of variation of 3.5 and 8.3%, respectively. Results of video densitometric quantitation did not differ significantly. However, data acquisition and evaluation is faster compared with densitometry and allows better archiving possibilities as required by the regulatory authorities. Both quantitation modes can be applied to routine control of pharmaceutical equipment cleanliness.
Supercritical Fluid Extraction of Halogenated Monoterpenes from the Red Alga Plocamium cartilagineum
Authors: Gao Donqhui , Okuda Roy , Lopez-Avila Viorica 
Published: February 2020

Abstract
Supercritical fluid extraction (SFE) of the marine red alga Plocamium cartilagineum, which is known to contain complex mixtures of halogenated monoterpenes, was investigated. P. cartilagineum samples were extracted by SFE with carbon dioxide and modified carbon dioxide containing up to 10% methanol at different pressure and temperature conditions to establish the optimum conditions for extraction. These conditions were then used in the extraction of halogenated monoterpenes from 2 different samples of P. cartilagineum: one from Davenport, CA, and the other from Casa Beach (San Diego, CA). Several halogenated monoterpenes isolated by conventional solvent extraction with methanol and purified by column chromatography were used as the reference compounds for the determination of the extraction efficiency in the SFE experients. Plocamium cartilagineum belongs to the red alga family—Plocamiaceae, and has been found to contain a large number of halogenated monoterpenes, whose structures typically contain 1–6 bromine and/or chlorine atoms. P. cartilagineum grows along the Pacific coast from Washington to Chile, the British Isles, Australia, and Spain. Interestingly, P. cartilagineum collected from different geographical areas in the world are all reported to produce halogenated monoterpenes, but of different structural types and halogen substitution patterns. Most of these halogenated monoterpenes have been found to exhibit varied biological activities, including antifungal, antimicrobial, and molluscicidal activity.
Enzyme Immunoassay for Aflatoxin B1-Lysine Adduct and Its Validation
Authors: Sujatha Nayak , Suryakala Sarilla , Rao Beedu Sashidhar 
Published: February 2020

Abstract
A simple procedure was developed for in vitro synthesis and characterization of aflatoxin B1-lysine adduct using aflatoxin B1, N-α-acetyl lysine and m-chloroperbenzoic acid (MCPBA). At a molar ratio of 1:16 (aflatoxin B1:N-α-cetyl lysine), the recovery of adduct was 62%. Analysis of the adduct by thinlayer chromatography showed a single spot (Rf= 0). Absorption spectra of the adduct showed 2 peaks at 275 and 335 nm. Liquid chromatographic (LC) analysis of th AFB1-lysine adduct showed a relative retention time of 2.1 min. Using the same epoxidation procedure, BSA-AFB1 adduct and ovalbumin-AFB1 adduct were synthesized for production of antibodies and as coating antigen, respectively. Control rat serum, spiked with AFB1-lysine adduct and subjected to LC analysis showed a retention time of 2.1 min, which is similar to that of AFB1-lysine reference standard, synthesized. Further, enzymatically hydrolyzed, control rat serum spiked with BSA-AFB1 adduct showed 2 peaks with retention times of 2.1 and 2.7 min. Based on the LC analysis, recovery of BSA-AFB1 in terms of AFB1-lysine adducts was 67 ± 5%. The major peak (2.1 min) accounted for 72% of the adduct; the second minor peak (2.7 min) accounted for 28% of the total AFB1-lysine adducts formed. Stability studies on the AFB1-lysine adduct synthesized, indicated that it was stable for 1 month. Antibody capture assay showed an absorbance of 0.9 to 1.0 at a dilution of 1:50 000 when ovalbumin-AFB1 was used as a coating antigen. Indirect competitive ELISA showed 50% displacement (IC50) of the antibodies at a concentration of 13 ng AFB1-lysine, whereas the IC50 for AFB1 was 7 ng. The recovery of AFB1-lysine adduct spiked to control rat serum followed by enzymatic hydrolysis and immunoanalysis (indirect ELISA) was 93 ± 6%. The enzyme immunoassay was validated by a rodent model, in which the animals were exposed to aflatoxin B1 (20 μg AFB1/kg body mass/day). The level of AFB1-lysine adduct in the rat serum was 27.3 ± 4.37 μg/mg albumin.
Simultaneous Determination of Six Triazolic Pesticide Residues in Apple and Pear Pulps by Liquid Chromatography with Ultraviolet Diode Array Detection
Authors: Bicchi Carlo , Cordero Chiara , Rubiolo Patrizia , Occelli Alessandro 
Published: February 2020

Abstract
A method is described for the simultaneous determination of diclobutrazol, flusilazole, flutriafol, hexaconazole, paclobutrazol, and tetraconazole in apple and pear pulps used in baby food at a limit of 0.01 mg/kg. Apple and pear pulp samples are subjected to selective solid-phase microdispersion (SPMD) with SPE-ED Matrix-38 and acetone–cyclohexane, and the extracts are cleaned up on a Florisil cartridge with hexane–cyclohexane–acetone. The extracts are then analyzed by liquid chromatography with ultraviolet detection, using an octadecylsilane column with a gradient-programmed acetonitrile–water mobile phase. Recoveries were determined by spiking apple and pear pulps with the 6 pesticides under investigation at 0.1, 0.05, 0.03, and 0.01 mg/kg. Six determinations were performed at each level for each pesticide. Recoveries were ≥70% at the 0.01 mg/kg level.
Multiresidue Determination of Organochlorine Pesticides and Polychlorinated Biphenyls in Milk by Gas Chromatography with Electron-Capture Detection after Extraction by Matrix Solid-Phase Dispersion
Authors: Yagüe Cristina , Bayarri Susana , Lázaro Regina , Conchello Pilar , Ariño Agustín , Herrera Antonio 
Published: February 2020

Abstract
A multiresidue analytical method based on matrix solid-phase dispersion was developed to analyze liquid milk for 22 organochlorine pesticides (OCPs) and 6 polychlorinated biphenyls (PCBs). Initial extraction is performed by loading 3 mL milk onto a 2.0 g octadecyl (C18)-bonded silica cartridge with n-hexane as the eluant. Neutral alumina column chromatography with sodium sulfate as the drying agent is used for further cleanup. The eluate is concentrated to 0.5 mL, and target analytes are determined by capillary gas chromatography with electron-capture detection. The optimized method was validated by determining accuracy (recovery percentages), precision (repeatability and reproducibility), and sensitivity (detection and quantitation limits) from analyses of milk samples fortified at 10 and 1 μg/L levels. Average recoveries were between 74 and 106% for all residues except β-HCH, β-endosulfan, and endosulfan sulfate. Both repeatability and reproducibility relative standard deviation values were &lt; 22% for all residues. Detection limits ranged from 0.02 to 0.12 μg/L and quantitation limits were between 0.02 and 0.62 μg/L. The proposed analytical method may be used as a fast and simple procedure in routine determinations of OCPs and PCBs in milk.
Enzyme Immunoassay of Staphylococcal Enterotoxins in Dairy Products with Cleanup and Concentration by Immunoaffinity Column
Authors: Lapeyre Christiane , Maire Tiphaine , Messio Sabine , Dragacci Sylviane 
Published: February 2020

Abstract
Two different immunoaffinity columns (IACs) were prepared for detection of staphylococcal enterotoxins (SETs) from dairy products. First, a specific IAC for staphylococcal enterotoxin A (SEA), IAC-1, was prepared by coupling monoclonal antibody (mAb) directed against SEA; second, a polyspecific IAC for SEA, staphylococcal enterotoxin B (SEB), staphylococcal enterotoxin C (SECs), and staphylococcal enterotoxin D (SED), IAC-2, was prepared by coupling a mixture of mAbs against SEA, SECs, and SED, and rabbit IgG against SEB. These columns were applied for detection of SETs in dairy products, after extraction, immunoaffinity chromatography, and enzyme immunosorbent assay (EIA). Overall recoveries from dairy products spiked with 1 ng SEA/25 g averaged 81.2% (range, 76–85%) on IAC-1. The repeated use of IAC-1 was then determined with good efficiency of 91.5%, in more than 10 runs. On the other hand, a recovery yield of 77%of SETs (SEA, SEB, SEC, and SED) from dairy products spiked with 2.5 ng of each enterotoxin per 25 g, was obtained with IAC-2. IAC-2 was also successfully subjected to the chromatography of naturally contaminated foods implicated in staphylococcal food poisoning outbreaks. This new extraction–concentration–immunoaffinity–chromatography method (ECIC) is very useful for improving staphylococcal enterotoxin detection and eliminating matrix effect in EIA of dairy products.
Broad-Spectrum Determination of Pesticides in Groundwater by Gas Chromatography with Electron Capture Detection, Nitrogen–Phosphorus Detection, and Tandem Mass Spectrometry
Authors: Frenich Antonia Garrido , Espada Maria Del Carmen Pablos , Vidal Jose Luis Martínez , Molina Luis 
Published: February 2020

Abstract
Gas chromatography with electron capture detector (ECD), nitrogen–phosphorus detector (NPD), and tandem mass spectrometry (MS/MS) was used to identify 36 pesticides, widely used to control various pest and diseases in vegetables, in water after a preconcentration step on C18 cartridges. The recoveries obtained ranged from 70 to 135% at a fortification level of 100 ng/L with relative standard deviations of &lt;36.2%. The limits of detection and quantitation were ≤48 and ≤160 ng/L, respectively. Important advantages of MS/MS over ECD and NPD in the determination of pesticides are also presented. The proposed analytical methodology was applied to the determination of pesticides in groundwater samples from an agricultural area, the Campo de Dalías (Almería, Spain). The most frequently encountered pesticides were endosulfan sulfate and metalaxyl, whereas the pesticide found at the highest concentration was fenamiphos.
Enzyme Assay for Identification of Pectin and Pectin Derivatives, Based on Recombinant Pectate Lyase
Authors: Hansen Karin M , Thuesen Annette B , Soderberg Jørgen R 
Published: February 2020

Abstract
A simple method was developed for fast identification of pectin, based on a recombinant endopectate lyase cloned from Aspergillus niger. When pectin was demethylated and treated with pectate lyase, β-elimination occurred, resulting in a double bond between C-4 and C-5 in the galacturonic acid residue of the released nonreducing end. The formation of double bonds produced an increase in light absorption, which was detected at 235 nm. The assay was tested on pectin of different origins (apple, orange, sugar beet, sunflower, celery, lemon), pectin derivatives (amidated pectin), and speciality types such as low molecular weight and low %DE (degree of esterification, percentage of galacturonic acid groups esterified with methanol) pectin. The highest response was given by pectate (pectin with %DE&lt;5) and the lowest by pectin extracted from sugar beet. No other gums (carboxymethylcellulose, carrageenan, locust bean gum, tragacanth, gellan, tamarind, xanthan, amylogum, sodium alginate, or agar) gave any response. Members of IPPA (International Pectin Producers Association) have evaluated the validity of the assay in a ring test. All members of the Association were able to identify pectin from other gums in a blind test. The method can replace more laborious and ambiguous identification tests which exist today.
Determination of Total Metals in Cultivated Oysters (Crassostrea gigas) from the Northwest Coast of Mexico by Microwave Digestion and Atomic Absorption Spectrometry
Authors: García-Rico Leticia , Ruiz Rita E Ramos , Jiménez Javier Vivian 
Published: February 2020

Abstract
Bivalves such as oysters often accumulate heavy metals, and therefore can be used to monitor changes of pollutant concentrations in the environment. Cultivated oysters from the northwest coast of Mexico are widely used for human consumption and thus have an important commercial value. Information was gathered on the concentration of these elements in oysters (Crassostrea gigas) cultivated on the coast of Sonora. Oysters were randomly collected from April to October 1997, from 6 different locations (65 individuals per site) in 4 different months. Metals were determined by microwave digestion followed by atomic absorption spectroscopy. The mean values (μg/g fresh weight) for each metal were: Cd, 0.76; Cu, 3.64; Zn, 17.71; Pb, 0.50; As, 0.05; Hg, 0.03; and Se, 0.21. The results show that, except for Cd, concentrations of regulated metals were under the maximum permitted values specified by regulatory agencies of Mexico and were comparable to those reported from other areas.
Slurry Atomization of Wheat-Milled Fractions for Electrothermal Atomic Absorption Spectrometric Determination of Nickel and Chromium
Authors: González M Mar , Gallego Mercedes , Valcárcel Miguel , Gómez-Cárdenas Gaspar 
Published: February 2020

Abstract
A slurry electrothermal atomic absorption spectrometric technique was used to determine Ni and Cr in wheat flour and its by-products. Slurries (3%, w/v) were prepared in a mixture of 15% HNO3–10% H2O2 as suspended medium. Differences in Ni and Cr contents due to origin and texture of the wheat and to the effects of the milling process were studied. Ni and Cr levels were more markedly influenced by the geographical origin of the wheat than by its texture. Both metals were related to the amount of bran present in each milled fraction and varied over the ranges of 212–298 ng/g (Ni) and 34–85 ng/g (Cr) in flours (with minimal bran contents); 297–460 ng/g (Ni) and 67–118 ng/g (Cr) in shorts; and 424–723 ng/g (Ni) and 106–165 ng/g (Cr) in brans. The Ni and Cr contents were not significantly affected by the technological processes typically performed in a flour-producing factory.
Quantitation of Nicotine in Tobacco Products by Capillary Electrophoresis
Authors: Clarke Michelle Bruffey 
Published: February 2020

Abstract
A simple and rapid capillary electrophoresis (CE) method was developed for the quantitation of nicotine in commercial tobacco products. The method involves a 6 min run at 30 kV, using a 50mM phosphate buffer (pH 2.5), paraquat as internal standard, and UV detection at 260 nm. Nicotine was extracted from tobacco products in &lt;15 min. Recoveries from spiked extracts were &gt;95%, and the extraction efficiencies of water, 1M HCl, 1M acetic acid, 5mM phosphate buffer (pH 2.5), and 1% triethanol amine were similar. Nicotine concentrations in 67 samples of cigarettes, cigars, and bidis varied between 0.37 and 2.96% (w/w). An established gas chromatography/mass spectrometry method using toluene extraction consistently yielded lower nicotine values than the CE method. Experimental evidence suggests that this is due to insufficient extraction of nicotine by toluene.
Optimization and Validation of Arsenic Determination in Foods by Hydride Generation Flame Atomic Absorption Spectrometry
Authors: Kabengera Charles , Bodart Patricia , Hubert Philippe , Thunus Leopold , Noirfalise Alfred 
Published: February 2020

Abstract
A hydride generation flame atomic absorption spectrometric method was developed and optimized to quantitate arsenic (As) in foods. A wet digestion of the samples with HNO3 + H2O2 was performed and excess oxidants were eliminated by addition of hydrochloric acid and urea. As5+ in As3+ was then reduced by potassium iodide. The As3+ solution was analyzed by generation of arsine with sodium tetrahydroborate. As determination ranged from 2.5 to 20 μg/L, with a determination coefficient of 0.997. The limits of detection (LOD) and quantitation (LOQ) were 0.6 and 2.1 μg/L, respectively. The method was validated and good results were obtained for recovery, precision, accuracy, LOD, and LOQ. This method is now used to analyze foods from Rwanda.
Rapid Food Decomposition by H2O2–H2SO4 for Determination of Total Mercury by Flow Injection Cold Vapor Atomic Absorption Spectrometry
Authors: Zenebon Odair , Sakuma Alice M , Dovidauskas Sergio , Okada Isaura A , Maio Franca D De , Lichtig Jaim 
Published: February 2020

Abstract
A mixture of 50% H2O2–H2SO4 (3 + 1, v/v) was used for decomposition of food in open vessels at 80°C. The treatment allowed rapid total mercury determination by flow injection cold vapor atomic absorption spectrometry. Cabbage, potatoes, peanuts paste, hazelnuts paste, oats, tomatoes and their derivatives, oysters, shrimps, prawns, shellfish, marine algae, and many kinds of fish were analyzed by the proposed methodology with a limit of quantitation of 0.86 ± 0.08 μg/L mercury in the final solution. Reference materials tested also gave excellent recovery.