bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Use of Electrodialysis to Prepare Aqueous Bread Extracts for Bromate Determination by Chemiluminescence
Authors: Himata Katsuichi , Warner Charles , Currie Douglas , Graves Qian , Diachenko Gregory 
Published: February 2020

Abstract
A cleanup procedure based on electrodialysis is described for the preparation of aqueous bread extracts for bromate determination by chemiluminescence. The technique utilizes electrophoresis with 3 chambers separated by semipermeable membranes. The relative merits of reverse osmosis (RO), ultrafiltration, and nanofiltration membranes with various molecular weight cutoffs were evaluated. The best results were obtained with an RO membrane manufactured from thin-film (composite) polysulfone as support for polyamide. A 0.14M sodium sulfate solution in the center or collection chamber provides optimum conductivity. Aqueous hydroxylamine sulfate (30mM) was selected for the anode compartment as a reductant for the anode oxidation products. The constant current mode at 150 mA with a potential of ca 100 volts was used. After electrophoretic separation, the bromate concentration in the collection chamber was typically 2 to 3 times greater than the concentration in the bread extract. The chemiluminescent reaction of bromate with sulfite with hydrocortisone as the enhancer was selected for detection of bromate. The emission, with a wavelength maximum at 575 nm, was found to “glow” rather than “flash” after the reagents were mixed; therefore, it was possible to optimize the light collection period. The method was validated with a variety of commercial bread products. White bread, hot dog buns, hamburger rolls, and a multigrain bread from 7 different manufacturers were studied.
Comparison of Total Folate Concentrations in Foods Determined by Microbiological Assay at Several Experienced U.S. Commercial Laboratories
Authors: Koontz John L , Phillips Katherine M , Wunderlich Kelli M , Exler Jacob , Holden Joanne M , Gebhardt Susan E , Haytowitz David B 
Published: February 2020

Abstract
Analysis of total folate concentration measured by microbiological assay in a variety of foods submitted in a routine manner to experienced laboratories that regularly perform folate analysis on fee-for-service basis was evaluated. Homogenates of fresh strawberries, frozen spinach, orange juice, frozen meat and vegetable pizza, dry macaroni, and dried pinto beans were prepared and stored under conditions previously determined to maintain stability of folate content. An aliquot of each composite and of 3 certified reference materials were sent on each of 4 occasions to 4 laboratories. Results for macaroni and pizza, the only folic acid-fortified foods, had considerably lower between-laboratory variation (CVB) with CVB of 9–11% versus &gt;45% for other foods. Mean total folate ranged from 14 to 279 μg/100 g for a mixed vegetable reference material, from 5 to 70 μg/100 g for strawberries, and from 28 to 81 μg/100 g for wholemeal flour. Only 1 laboratory reported using a tri-enzyme extraction, and all laboratories used folic acid fortified foods as internal control materials. Users of commercial total folate analysis should understand the uncertainty in values determined by microbiological assay, particularly for foods containing primarily naturally occurring folate, which may not be apparent when replicate samples are not submitted for analysis.
Extraction of Fipronil and Thiobencarb from Anaerobic Water Samples Using Solid-Phase Extraction
Authors: Doran Gregory , Helliwell Stuart , Eberbach Philip 
Published: February 2020

Abstract
Anaerobic water samples containing levels of soluble Fe(II) may form insoluble Fe(III) particulates that could hinder subsequent extraction and analysis. Solid-phase extraction (SPE) cartridges could become blocked by this material, reducing the volume that can be processed. The ability of ascorbic acid to reduce these Fe(III) colloids and/or to prevent further oxidation of Fe(II) by dissolved oxygen during sampling was investigated and compared to sample stabilization with hydrochloric acid. Ascorbic acid (5%, w/v) proved the most effective treatment because it prevented 95% of the dissolved iron in the sample from precipitating during processing, compared to 40% in untreated samples. The effect of ascorbic acid addition on degradation of 2 rice pesticides, fipronil and thiobencarb, was investigated and compared to degradation rates in water. Pesticide reduction by ascorbic acid over a 3 h period was insignificant compared to the natural degradation occurring in deionized water. While this method was shown to increase sample processing time, it also allowed the processing of large-volume anaerobic water samples (150 mL) that were previously not extractable due to rapid obstruction of the SPE cartridge.
The Absorption and Metabolism of Modified Amino Acids in Processed Foods
Authors: Finot Paul-André 
Published: February 2020

Abstract
The chemical reactions involved in the modifications of amino acids in processed food proteins are described. They concern the Maillard reaction, reaction with polyphenols and tannins, formation of lysinoalanine during alkaline and heat treatments, formation of isopeptides, oxidation reaction of the sulfur amino acids, and isomerization of the L-amino acids into their D-form. Information on the digestion, absorption, and urinary excretion of the reaction products obtained by using conventional nutritional tests is given. The studies that have been made on the metabolism of these molecules by using a radioisotopic approach to follow their kinetics in the organism after ingestion are also reviewed. This approach provides unique data on the quantitation of the metabolic pathways and on the kinetics of the metabolic processes involved.
Validation of a Capillary Electrophoresis Method for Analysis of Rabeprazole Sodium in a Pharmaceutical Dosage Form
Authors: Garcia Cássia V , Sippel Juliana , Sfair Leticia L , Garcia Silvia S , Jablonski André , Steppe Martin , Schapoval Elfrides E S 
Published: February 2020

Abstract
Rabeprazole sodium is an antisecretory agent that inhibits the enzyme H+/K+ ATPase present in the stomach parietal cells. There are few data about its quantitative determinations in laboratorial routines. Capillary electrophoresis is a method being used increasingly for analysis of pharmaceutical compounds, the main advantages of which are the simplicity of instrumentation, low consumption of sample and reagents, and fast analysis. The aim of this study was to develop and validate a capillary electrophoresis method for determination of rabeprazole sodium in coated tablets. The conditions used were a bare fused silica capillary with 48.0 cm length (39.5 cm effective) and 75 μm id; a 10mM, pH 9.0, sodium tetraborate run buffer; a diode array detector set at 291 nm; hydrodynamic injection (50 mbar/5 s); and a voltage of 20 kV. HP Chemstation CE rev. A.06.03 software was used for system control, data acquisition, and analysis. The method was demonstrated to be linear in the concentration range of 5.0–40.0 μg/mL (r = 0.9993), precise (interday relative standard deviation = 0.49), accurate (mean recovery = 103.1%), and specific. The limits of detection and quantitation were 1.29 and 3.91 μg/mL, respectively.
Multiresidue Method for Simultaneous Determination of Ten Quinolone Antibacterial Residues in Multimatrix/Multispecies Animal Tissues by Liquid Chromatography with Fluorescence Detection: Single Laboratory Validation Study
Authors: Verdon Eric , Couedor Pierrick , Roudaut Brigitte , Sandérs Pascal 
Published: February 2020

Abstract
Quinolone antibacterials are veterinary drugs authorized for use in food animal production. The analysis of residual amounts of drugs in food from animal origin is important for quality control of products for consumers. For this purpose, Maximum Residue Limits (MRLs) have been set up by a European Union Council Regulation on Veterinary Drug Residues (No. 90/2377/EEC and subsequent), and 8 quinolones received MRLs at concentration levels depending on both the matrix and the animal species of interest. A method was developed for screening and confirming 10 quinolone residues (ciprofloxacin, danofloxacin, difloxacin, enrofloxacin, flumequine, marbofloxacin, nalidixic acid, norfloxacin, oxolinic acid, sarafloxacin) in a wide variety of matrixes of different animal species. It involves extraction of the residues from the biological tissues/fluids by acidic aqueous solution, centrifugation and filtration prior to injection on a C18 narrow-bore column, and detection through a 3-step-mode fluorescence detector. The method was validated during a 2-week study for a set of 8 species-matrixes (i.e., bovine raw milk, bovine muscle, porcine muscle, porcine kidney, porcine liver, fish flesh and skin, poultry muscle, whole egg). Residues were quantified down to 15 μg/kg with limits of detection and quantitation ranging from 4 to 11 and 13 to 36 μg/kg, respectively, which are sufficient compared to the wide range of MRLs set for these substances (from 30 μg/kg for danofloxacin in milk to 1900 μg/kg for difloxacin in poultry liver). The limit of performance of the method in terms of CCα and CCβ, the critical concentrations stated in the Decision No. 2002/657/EC and the ISO Standard No. 11843, has been calculated for the authorized (MRL) substances but only estimated in the case of the nonauthorized (non-MRL) substances.
Determination of Deoxynivalenol in Cereals and Cereal Products by Immunoaffinity Column Cleanup with Liquid Chromatography: Interlaboratory Study
Authors: MacDonald Susan J , Chan Danny , Brereton Paul , Damant Andrew , Wood Roger ,   Collaborators:, Dao Duy K , Felgueiras I , Feron T , Herry M-P , Ioannou-Kakouri E , Koch P , Krska R , Majerus P , Nesbit J , Reuter M , Stangroom S , Symonds P , Weber R 
Published: February 2020

Abstract
An interlaboratory study was performed on behalf of the UK Food Standards Agency to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatographic (LC) method for the determination of deoxynivalenol in a variety of cereals and cereal products at proposed European regulatory limits. The test portion was extracted with water. The sample extract was filtered and applied to an immunoaffinity column. After being washed with water, the deoxynivalenol was eluted with acetonitrile or methanol. Deoxynivalenol was quantitated by reversed-phase LC with UV determination. Samples of artificially contaminated wheat-flour, rice flour, oat flour, polenta, and a wheat based breakfast cereal, naturally contaminated wheat flour, and blank (very low level) samples of each matrix were sent to 13 collaborators in 7 European countries. Participants were asked to spike test portions of all samples at a range of deoxynivalenol concentrations equivalent to 200–2000 ng/g deoxynivalenol. Average recoveries ranged from 78 to 87%. Based on results for 6 artificially contaminated samples (blind duplicates), the relative standard deviation for repeatability (RSDr) ranged from 3.1 to 14.1%, and the relative standard deviation for reproducibility (RSDR) ranged from 11.5 to 26.3%. The method showed acceptable within-laboratory and between-laboratory precision for all 5 matrixes, as evidenced by HorRat values &lt;1.3.
Preconcentration and Determination of Tellurium in Garlic Samples by Hydride Generation Atomic Absorption Spectrometry
Authors: Kaplan Marcos M , Cerutti Soledad , Salonia José A , Gásquez José A , Martinez Luis D 
Published: February 2020

Abstract
A procedure for the determination of traces of total tellurium (Te) in garlic (Allium sativa) is described that combines hydride generation atomic absorption spectrometry with preconcentration of the analyte by coprecipitation. The samples, each spiked with lanthanum nitrate (20 mg/L), are introduced into an Amberlite XAD-4 resin and mixed with ammonium buffer (pH 9.1). Te is preconcentrated by coprecipitation with the generated lanthanum hydroxide precipitate. The precipitate is quantitatively collected in the resin, eluted with hydrochloric acid, and then transferred into the atomizer device. Considering a sample consumption of 25 mL, an enrichment factor of 10 was obtained. The detection limit (3σ) was 0.03 μg/L, and the precision (relative standard deviation) was 3.5% (n = 10) at the 10 μg/L level. The calibration graph using the preconcentration system for Te was linear with a correlation coefficient of 0.9993. Satisfactory results were obtained for the analysis of Te in garlic samples.
Liquid Chromatographic Determination ofMalachite Green and Leucomalachite Green (LMG) Residues in Salmon with in situ LMG Oxidation
Authors: Andersen Wendy C , Roybal José E , Turnipseed Sherri B 
Published: February 2020

Abstract
A liquid chromatography (LC) method is presented for the quantitative determination of malachite green (MG) in salmon. MG and leucomalachite green (LMG) residues were extracted from salmon tissue with ammonium acetate buffer and acetonitrile, and then isolated by partitioning into dichloromethane. LMG was quantitatively oxidized to the chromic MG by reaction with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. Samples were then cleaned up by solid-phase extraction with alumina and propylsulfonic acid phases. Extracts were analyzed for MG by LC with visible detection at 618 nm using isocratic elution and a C18 column. The method was validated in 35 farm-raised salmon (Salmo salar) tissues fortified at 1, 2, 4, and 10 ng/g (ppb) with an average recovery of 95.4% and a relative standard deviation of ±11.1%, and in 5 canned salmon (Oncorhynchus gorbuscha) samples fortified at 10 ng/g with an average recovery of 88.9 ± 2.6%. This study also included the determination of MG and LMG residues in tissues from salmon that had been treated with MG. MG was quantitatively determined at the method detection limit of 1 ng/g.
Determination and Confirmation of Malachite Green and Leucomalachite Green Residues in Salmon Using Liquid Chromatography/Mass Spectrometry with No-Discharge Atmospheric Pressure Chemical Ionization
Authors: Turnipseed Sherri B , Andersen Wendy C , Roybal José E 
Published: February 2020

Abstract
A liquid chromatography/mass spectrometry (LC/MS) method was developed to quantitate and confirm residues of leucomalachite green (LMG) in salmon tissue after their conversion to chromic malachite green (MG) in the extraction process. The method uses no-discharge atmospheric pressure chemical ionization (APCI) in conjunction with an ion-trap instrument to generate product-ion spectra. In the sample preparation procedure, salmon tissue is extracted with acetonitrile/buffer, the LMG residue is partitioned into methylene chloride, the LMG is converted to MG using an organic oxidizing agent, and the MG is isolated on alumina/propylsulfonic acid solid-phase extraction cartridges. The method was validated by fortifying salmon with different levels of LMG, and then detecting the residue as MG. The LC/MS conditions, including a comparison of electrospray and no-discharge APCI, were evaluated and optimized. MG was not confirmed in any of the control tissue extracts, and all fortified samples analyzed during validation met the confirmation criteria as described. In addition to providing confirmatory data, this method can provide an alternative method for quantitation of MG in salmon. The recoveries of LMG, measured as MG by this LC/MS method, at fortification levels of 1–10 ng/g were very high (86–109%), with low relative standard deviation(RSD) values (6.4–13%). The results agreed very closely with those obtained for the same extracts using an LC/VIS procedure, indicating that matrix suppression was not an issue. The presence of LMG in salmon tissue samples fortified at 0.25 ng/g was confirmed by this method, with an average recovery of 70.1% and an RSD of 12.0%. Sample extracts from fish exposed to MG were also analyzed.
Determination of Ionization Constant (pKa) and Octanol–Water Partition Coefficient (Log P) of Cyclopiazonic Acid
Authors: Sobolev Victor S 
Published: February 2020

Abstract
The ionization constant (pKa) and the octanol–water partition coefficient (log P) of the important mycotoxin cyclopiazonic acid (CPA) were determined by means of potentiometric titration, and the lipophilicity profile (log D) was calculated. Under the experimental conditions, pKa of CPA = 2.97 ± 0.09, log P = 3.83 ± 0.10, and log D at pH 7.4 = −0.58.
Determination of Trace Amounts of Cobalt Using 1-(5-Bromo-2-Pyridylazo)-2-Naphthol-6-Sulfonic Acid-Cu(II)-Co(II) Competitive Replacement Complexation
Authors: Gao Hong-Wen 
Published: February 2020

Abstract
The chromophore 1-(5-bromo-2-pyridylazo)-2-naphthol-6-sulfonic acid (BPANS) has been used to sensitively complex Cu(II) and Co(II) in aqueous solution at pH 9.43. The spectral correction technique was applied to characterize the complexes, and results showed that both Cu(BPANS)2 and Co(BPANS)2 were formed. Trace Co2+ replaced the Cu(II) in the Cu-BPANS complex, so the competitive replacement complexation (CRC) was used to improve the analytical selectivity. A novel light-absorption ratio variation approach (LARVA) was described as one of the most sensitive methods. The combination of CRC and LARVAwas applied to the quantitative detection of Co(II) at the ng/mL level. The limit of detection was only 2.0 ng/mL Co, and the analysis of water samples demonstrated satisfactory results.
Multiresidue Determination of Pesticides in Sediment by Ultrasonically Assisted Extraction and Gas Chromatography/Mass Spectrometry
Authors: Kawata Kuniaki , Asada Takashi , Oikawa Kikuo , Tanabe Akiko 
Published: February 2020

Abstract
Agas chromatographic/mass spectrometric (GS/MS) method was developed for the multiple determination of pesticides in sediment. The investigated pesticides included 85 compounds, i.e., 13 fungicides, 43 herbicides, and 29 insecticides. The pesticides were extracted from sediment samples by an ultrasonically assisted procedure. The extract was cleaned up by using reversed-phase column chromatography followed by normal-phase column chromatography. A styrene-divinylbenzene copolymer cartridge and a silica gel cartridge were used as the reversed-phase column and the normal-phase column, respectively. The compounds were determined by GC/MS with 2 internal standard compounds. The overall recoveries were 70–105%, and the relative standard deviations ranged from 1.5 to 18%. The minimum detectable concentrations were 2–10 μg/kg. This method was successfully applied to sediment samples from the Shin River in Niigata, Japan. Twenty-five pesticides (6 fungicides, 11 herbicides, and 8 insecticides) were detected in the sediment samples. The concentrations of the detected pesticides ranged from 3 to 69 μg/kg. Herbicides were found May through July; insecticides and fungicides were found July through August, and during July through September, respectively. The presence of pesticides in the river sediment was correlated with the time of pesticide application in the Shin River basin.
High-Performance Thin-Layer Chromatography with Densitometry for the Determination of Ciprofloxacin and Impurities in Drugs
Authors: Krzek Jan , Hubicka Urszula , Szczepańczyk Justyna 
Published: February 2020

Abstract
A thin-layer chromatographic (TLC)-densitometric method has been developed for identification and quantification of ciprofloxacin (Rf = 0.61) and an ethylenediamine compound (Rf = 0.42), a desfluoro compound (Rf = 0.48), by-compound A (Rf = 0.53), and fluoroquinolonic acid (Rf = 0.68) as ciprofloxacin degradation products in pharmaceutical preparations. By using chloroform–methanol–25% ammonia (43 + 43 + 14, v/v/v) as the mobile phase and silica gel 60 F254 high-performance TLC plates as the stationary phase, it was possible to separate individual constituents that, when subjected to ultraviolet (UV) densitometric analysis at 330 nm for fluoroquinolonic acid and 277 nm for the other compounds, gave well developed peaks allowing easy qualitative and quantitative analyses. DMSO–methanol (1 + 1) was used to extract drug constituents. The method showed high sensitivity (limit of detection 10 to 44 ng), a wide linearity range (3 to 20 μg/mL), and good precision (2.32 to 6.46% relative standard deviation) and accuracy (percentage recoveries 98.62 to 101.52%) for individual constituents.
Identification and Quantitation of Polymyxin B, Framycetin, and Dexamethasone in an Ointment by Using Thin-Layer Chromatography with Densitometry
Authors: Krzek Jan , Maślanka Anna , Lipner Pawel 
Published: February 2020

Abstract
A new thin-layer chromatographic-densitometric method has been developed for rapid identification and quantitative determination of polymyxin B, framycetin, and dexamethasone in a dental ointment. Silica gel 60 and F254 silica gel 60 plates were used for separating antibiotics and dexamethasone acetate, respectively. When determining framycetin and polymyxin B, chromatograms were developed by using 2 mobile phases, namely methanol and methanol–n-butanol–ammonia (25%)–chloroform (14 + 4 + 9 + 12, v/v/v/v/). The densitometric measurements were made at 550 nm after detection with 0.3% ninhydrin solution. Dexamethasone was determined by using the mobile phase cyclohexane–ethyl acetate (2 + 3, v/v) and ultraviolet densitometric recording at 245 nm. The results obtained for individual constituents with the chromatographic-densitometric method demonstrate similar accuracy, relative standard deviation values from 1.49 to 2.47%, and relative error values from 0.02 to 0.81% and are comparable to those obtained with the reference methods.
Development and Validation of a Thin-Layer Chromatographic Method for Determination of Chloramphenicol Residues on Pharmaceutical Equipment Surfaces
Authors: Vovk Irena , Simonovska Breda 
Published: February 2020

Abstract
A thin-layer chromatographic (TLC) method with densitometric quantitation using the absorption reflectance mode at 280 nm was developed and validated for the determination of chloramphenicol residues in controlling pharmaceutical equipment cleanliness. Simulated samples at residue levels 0.5, 1, and 1.2 mg/m2 were prepared by spreading the calculated amount of chloramphenicol solution on a 10 dm2 stainless steel surface. After evaporation of the solvent, the residue was removed by 2 methanol-wetted cotton swabs, which were then extracted with methanol. The extract was applied on a high-performance TLC (HPTLC) silica gel F254 plate together with standards ranging from 10 to 60 ng. Plates were developed in a horizontal developing chamber from both sides (36 applications per plate) by using n-hexane–ethyl acetate (35 + 65, v/v) as developing solvent. The mean recovery (n = 6) at 1 mg/m2 was 95.8%, and the coefficient of variation was 5.8%. The absolute detection limit was 3 ng, and the quantitation limit 10 ng. The method detection limit was 0.3 mg/m2 by swabbing 2.5 dm2 and 0.075 mg/m2 by swabbing 10 dm2. Chloramphenicol was stable on the plate 2 h before and 24 h after development. Additionally, it was stable during 7 days storage on the cotton swabs in the solvent at room temperature and in diluted standard solution stored in darkness at 4°C. The method can be applied to routine control of pharmaceutical equipment cleanliness by sampling from the stainless steel surface areas of 2.5 to 10 dm2, and an acceptable residue limit of 1 mg/m2.