bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of Oxalate in Urine, Using an Amperometric Biosensor with Oxalate Oxidase Immobilized on the Surface of a Chromium Hexacyanoferrate-Modified Graphite Electrode
Authors: Milardović Stjepan , Grabarić Zorana , Tkalčec Mihael , Rumenjak Vlatko 
Published: February 2020

Abstract
A novel enzymatic amperometric method is described for the determination of oxalic acid in urine. An amperometric biosensor was made by immobilizing oxalate oxidase on the surface of a chromium(III) hexacyanoferrate-modified graphite electrode by using a bovine serum albumin and glutaraldehyde cross-linking procedure. The enzyme biocatalyzes oxalate decomposition in the presence of oxygen into carbon dioxide and hydrogen peroxide. The oxalate concentration, which is proportional to the amount of hydrogen peroxide, was determined amperometrically by measuring the current resulting in the reduction of hydrogen peroxide at a very low working potential (0.05 V versus the Hg | Hg2Cl2 | 3M KCl electrode), which minimized the influence of the possible interferences present in human urine. All experiments were performed with succinic buffer, pH 3.8, containing 0.1M KCl and 5.4mM ethylenediaminetetraacetic acid. In an aqueous solution of pure oxalic acid, the biosensor showed good linearity in a concentration range of 2.5–100μM without the use of a dialysis membrane. For untreated urine samples, a high correlation (R2 = 0.9949) was obtained between oxalate concentrations added to urine samples and oxalate recoveries calculated for determinations with the described oxalate biosensor.
Voltammetric Behavior and Analytical Applications of Lomefloxacin, an Antibacterial Fluorquinolone
Authors: Álvarez-Lueje Alejandro , López Camilo , Núñez-Vergara Luis J , Squella Juan A 
Published: February 2020

Abstract
Lomefloxacin was reduced on a dropping mercury electrode, producing one or more peaks, depending on the pH of the aqueous medium. Coulometric measurements gave an experimental value of 1 electron for the main peak. Electrolysis was followed by UV spectrophotometry and liquid chromatography (LC), showing that a new band at 413 nm appeared for the electrolysis product in an acidic medium. Furthermore, by using UV spectrophotometry, an apparent pKa value of 6.75 ± 0.05 was obtained for lomefloxacin corresponding to the carboxyl moiety in the 3-position. For analytical studies, the differential pulse polarographic mode in 0.1N HCl was selected. The repeatability and reproducibility of the method were adequate (coefficient of variation [CV], 0.51%). The calibration curve method was used for the lomefloxacin concentration range of 7.0 × 10−6 to 7.0 × 10−5M. The detection and quantitation limits were 1.0 × 10−6 and 6.9 × 10−6M, respectively. For purposes of comparison, both UV spectrophotometric and LC (with UV and fluorimetric detection) methods were developed. The polarographic method showed good selectivity with respect to both excipients and degradation products. The recovery study showed a CV of &lt;2% and an average recovery of 99.5% and it was not necessary to treat the sample before analysis. The method was applied to the determination of the uniformity content of lomefloxacin commercial tablets. The polarographic method was also successfully applied to the quantitation of lomefloxacin in urine, and the renal excretion profile was also determined.
Application of Liquid Chromatography to the Simultaneous Determination of Acetylsalicylic Acid, Caffeine, Codeine, Paracetamol, Pyridoxine, and Thiamine in Pharmaceutical Preparations
Authors: Ramos-Martos Natividad , Aguirre-Gómez Francisco , Molina-Díaz Antonio , Capitán-Vallvey Luis F 
Published: February 2020

Abstract
This paper describes a rapid reversed-phase liquid chromatographic method, with UV detection, for the simultaneous determination of acetylsalicylic acid, caffeine, codeine, paracetamol, pyridoxine, and thiamine in pharmaceutical preparations. A reversed-phase C18 Nucleosil column is used. The mobile phase consists of 2 successive eluants: water (5 min) and acetonitrile–water (75 + 25, v/v; 9 min), both adjusted to pH 2.1 with phosphoric acid. Before determination acetylsalicylic acid is completely converted to salicylic acid by alkaline hydrolysis. Salicylic acid, caffeine, paracetamol, pyridoxine, and thiamine are all detected at 285 nm, whereas codeine is detected at 240 nm. Calibration curves were linear for salicylic acid, caffeine, paracetamol, and pyridoxine in the range of 50–500 mg/L, and for codeine and thiamine in the range of 50–1000 mg/L. The method was applied to the analysis of 13 fortified commercial pharmaceutical preparations. Recoveries ranged from 92.6 to 105.5%, with relative standard deviations of 1.1–5.8%.
Extension of AOAC Official Method 996.01 to the Analysis of Standard Reference Material (SRM) 1846 and Infant Formulas
Authors: Satchithanandam Subramaniam , Fritsche Jan , Rader Jeanne I 
Published: February 2020

Abstract
There is currently no official method for the analysis of fatty acids (including trans fatty acids) in infant formulas. AOAC Official Method 996.01 for Fat Analysis in Cereal Products was extended to the analysis of milk-based infant formula Standard Reference Material (SRM)1846 to determine its applicability for use with infant formulas. Following the analysis of SRM 1846, 2 infant formulas, one milk-based liquid and one soy-based powdered infant formula, were analyzed for total fatty acid composition. Fatty acid methyl esters were prepared and analyzed by gas chromatography. The results of the analysis of SRM 1846 show that the mean analyzed values were highly reproducible as indicated by low coefficients of variation (CV). The CVs were &lt;5% for the major fatty acids. Mean analyzed values for individual fatty acids in SRM 1846 were within ± 1 standard deviation of the certificate values. The analyzed value for total fat as triglycerides (26.27 ± 0.25%) agreed well with the certificate value (27.1 ± 0.59%). Analyses of infant formulas showed that the concentrations of linoleic acid and fat meet the requirements for such formulas.
Determination of Glyphosate and Aminomethylphosphonic Acid in Crops by Capillary Gas Chromatography with Mass-Selective Detection: Collaborative Study
Authors: Alferness Philip L , Wiebe Lawrence A ,   Collaborators:, Anderson L , Bennett O , Bosch M , Clark D , Claussen F , Colin T , Cook C , Davis H , Ely V , Graham D , Grazzini R , Hickes H , Holland P , Hom W , Ingram R , Ling Y , Markley B , Peoples G , Pitz G , Robert G , Robinson C , Sen L , Sensue A , South N , Steginsky C , Summer S , Trower T , Wieczorek P , Zheng S 
Published: February 2020

Abstract
A collaborative study was conducted to validate a method for the determination of glyphosate and aminomethylphosphonic acid (AMPA) in crops. The analytes are extracted from crops with water, and the crude extracts are then subjected to a cation exchange cleanup. The analytes are derivatized by the direct addition of the aqueous extract into a mixture of heptafluorobutanol and trifluoroacetic anhydride. The derivatized analytes are quantitated by capillary gas chromatography with mass-selective detection (MSD). The collaborative study involved 13 laboratories located in 5 countries 12 laboratories returned valid data sets. The crops tested were field corn grain, soya forage, and walnut nutmeat at concentrations of 0.050, 0.40, and 2.0 mg/kg. The study used a split-level pair replication scheme with blindly coded laboratory samples. Twelve materials were analyzed, including 1 control and 3 split-level pairs for each matrix, 1 pair at each nominal concentration. For glyphosate, the mean recovery was 91%, the average intralaboratory variance, the repeatability relative standard deviation (RSDr), was 11%, and the interlaboratory variance, the reproducibility relative standard deviation (RSDR), was 16%. For AMPA, the mean recovery was 87%, the RSDr was 16%, and the RSDR was 25% at mg/kg levels.
Furanocoumarins in Celery and Parsnips: Method and Multiyear Canadian Survey
Authors: Lombaert Gary A , Siemens Karin H , Pellaers Peter , Mankotia Mohan , Ng Winnie 
Published: February 2020

Abstract
The natural occurrence of biologically active furanocoumarins in common vegetables is an area of increasing interest with respect to human health. In this study, an efficient, rugged, and sensitive liquid chromatographic method with ultraviolet photodiode array detection was developed for the estimation of 5 biologically active furanocoumarins (psoralen, bergapten, xanthotoxin, trioxsalen, and angelicin) in celery and parsnips. When authentic samples were spiked with a mixture of furanocoumarins at individual levels of 2 to 10 μg/g, the method produced overall recoveries of 77 and 75%of all furanocoumarins from celery and parsnips, respectively. The method was applied in 2 laboratories to a multiyear survey of more than 200 samples. Of 110 parsnips samples, 109 (99%) contained quantitatable levels of furanocoumarins. The mean level of total furanocoumarins in the positive parsnip samples was 15.1 μg/g; the maximum level detected was 145 μg/g. Of 114 celery samples, 88 (77%) contained quantitatable levels of furanocoumarins. The mean level of total furanocoumarins in the positive celery samples was 1.9 μg/g; the maximum level detected was 15.2 μg/g. Xanthotoxin and bergapten were the most commonly detected furanocoumarins in both celery (68 and 63%) and parsnips (97 and 96%). Xanthotoxin had the highest mean level of positives in both celery (1.3 μg/g) and parsnips (8.5 μg/g). Little year-to-year variation in either total furanocoumarin levels or incidence was noted.
Recent Advances in Thin-Layer Chromatography of Pesticides
Authors: Sherma Joseph 
Published: February 2020

Abstract
Advances in the applications of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) for the separation, detection, and qualitative and quantitative determination of pesticides, other agrochemicals, and related compounds are reviewed for the period 1998–2000. Analyses are covered for a variety of samples, such as food, biological, and environmental, and for residues of pesticides of various types, including insecticides, herbicides, and fungicides, belonging to different chemical classes. References on formulation analysis, hydrophobicity studies, and the use of TLC and thin-layer radiochromatography (TLRC) for studies of pesticide metabolism, degradation, uptake, and related studies are also included.
Pesticide Residue Analysis (1999–2000): A Review
Authors: Sherma Joseph 
Published: February 2020

Abstract
The literature of pesticide residue analysis is reviewed selectively for the period 1999–2000. Analyses of a wide range of pesticide classes and sample types, as well as some related organic pollutants, are covered. Studies of exposure and monitoring as well as pesticide degradation, persistance, leaching, mobility, and metabolism studies are included.
Determination and Confirmation of the Amnesic Shellfish Poisoning Toxin, Domoic Acid, in Shellfish from Scotland by Liquid Chromatography and Mass Spectrometry
Authors: Hess Philipp , Gallacher Susan , Bates Lesley A , Brown Nigel , Quilliam Michael A 
Published: February 2020

Abstract
During 1998 and early 1999, shellfish samples from sites in Scotland were found to contain the amnesic shellfish poisoning toxin, domoic acid (DA). Two different techniques, liquid chromatography (LC) with UV diode-array detection and LC with mass spectrometric (MS) detection, were used to detect and confirm DA in shellfish extracts. The LC/UV method was validated for routine monitoring by recovery experiments on spiked mussel and scallop tissues with a certified mussel tissue used as reference material. Crude extracts of selected samples as well as extracts cleaned with strong anion exchange (SAX) were analyzed by both LC/UV and LC/MS. Good correlation (linear regression r2 = 0.996, slope = 0.93) between the 2 methods was found for cleaned extracts. Analyses of crude extracts by LC/UV produced false-positive results in 2 crab samples, whereas LC/MS analyses gave accurate results. It was concluded that LC/UV is a valid approach for routine monitoring of DA in shellfish when cleanup is performed with a SAX cartridge to prevent false positives. A variety of shellfish species were surveyed for DA content, including Pecten maximus (king scallops), Chlamys opercularis (queen scallop), Mytilus edulis (blue mussels), Cancer pugaris (crab), and Ensis ensis (razor fish). The highest concentration of DA was 105 μg/g in Pecten maximus.
Development of Reference Materials for Paralytic Shellfish Poisoning Toxins
Authors: Egmond Hans P van , Mouriño Antonio , Burdaspal Pedro A , Boenke Achim ,   Collaborators:, Alvito P , Arevalo F , Botana-López L M , Bustos J , Dietrich R , Donald M , Franco Soler J M , Gago Martinez A , Hald B , Helle N , Hummert C , Ledoux M , Legarda T , Luckas B , Mesego A , Paulsch W E , Rodriguez-Vieytes M , Salgado C , Stockemer J , Usleber E , van den Top H J , Walther L , Walther M , Winkler F 
Published: February 2020

Abstract
A project was undertaken to develop mussel reference materials that were certified for their mass fractions of saxitoxin and decarbamoyl-saxitoxin. Fifteen laboratories from various European countries participated. Three of these had major responsibility for substantial parts of the work and overall coordination of the project. The project involved 4 main activities: (1) procurement and characterization of calibrants; (2) improvement of analytical methodology; (3) preparation of reference materials, including homogeneity and stability studies; (4) 2 interlaboratory studies and a certification exercise. The joint activities resulted in 3 homogeneous and stable reference materials: 2 lyophilized mussel materials with and without naturally incurred paralytic shellfish poisoning (PSP) toxins, and a saxitoxin enrichment solution. The reference materials were certified with respect to their saxitoxin and decarbamoyl-saxitoxin content. The lyophilized mussel material with PSP toxins (CRM 542) contained &lt;0.07 mg saxitoxin·2HCl/kg and 1.59 ± 0.20 mg decarbamoyl-saxitoxin·2HCl/kg. The lyophilized mussel material without PSP toxins (CRM 543) contained &lt;0.07 mg saxitoxin·2HCl/kg and &lt;0.04 mg decarbamoyl-saxitoxin·2HCl/kg. The certified value of the saxitoxin mass fraction in the saxitoxin enrichment solution (CRM 663) was 9.8 ± 1.2 μg/g.
Determination of Gliclazide in Pharmaceutical Preparations by Capillary Gas Chromatography with Cool On-Column Injection and Elimination of the Matrix Effect
Authors: Krzek Jan , Czekaj Janusz , Moniczewska Maria , Rzeszutko Włodzimierz 
Published: February 2020

Abstract
Conditions were established for the identification and quantitation of gliclazide in pharmaceutical preparations by capillary gas chromatography with flame ionization detection and cool on-column injection. Gliclazide was extracted with methanol and, after filtration, assayed on a (25 m × 0.25 mm id, 0.2 μm film thickness) CP-WAX 58 (FFAP)–CB WCOT fused silica column. Because the available preparations were of various origins and, therefore, could differ in auxiliary substances and their qualitative parameters, the influence of the matrix constituents on the analytical results was taken into account. Good separation conditions were established for the developed method. The retention time of gliclazide is about 36 min and differs from the retention times of the internal standard (approximately 29 min) and additional peaks present in chromatograms (20–26 min), which were assigned to matrix constituents. The recoveries of gliclozide were high and reached 96.5%. The developed method is characterized by selectivity and precision (relative standard deviation 0.38–1.26%), a wide range of linearity (0.1–10.0 mg/mL), and a limit of detection of 30 ng. In addition, the results of chromatographic analyses calculated in 3 ways were compared with those obtained by UV spectrophotometry. The suggested technique of cool on-column injection, in contrast with split-splitless injection (used in preliminary investigations), reduces to a minimum the possibility of thermal decomposition of gliclazide.
Liquid Chromatographic Determination of Simple Phenolic Compounds in Waste Waters from Olive Oil Production Plants
Authors: Ceccon Luciano , Saccù Debora , Procida Giuseppe , Cardinali Stefano 
Published: February 2020

Abstract
A method was developed for the determination of simple phenolic compounds (PCs) in waste waters from olive oil production plants by liquid chromatography (LC). The sample under examination was acidified to pH 2 to precipitate proteins, acetone was added to eliminate the colloidal fraction, and hexane was used for extraction to eliminate lipidic substances. The solution obtained was filtered and injected into the LC system; the wavelength selected for the spectrophotometric detection was specific for PCs, so that carbohydrates, organic acids, and short-chain free fatty acids did not interfere. Recoveries of 9 PCs spiked to a real sample were 90–100% for concentrations ranging from 20 to 2000 mg/L for each analyte.
Analysis of Agricultural Commodities and Foods for Alternaria Mycotoxins
Authors: Scott Peter M 
Published: February 2020

Abstract
Fungi of the genus Alternaria are parasitic on plants and other organic materials. A. alternata is a frequently occurring species of particular interest because it produces a number of mycotoxins, including alternariol (AOH), alternariol monomethyl ether (AME), altenuene (ALT), altertoxins I, II, and III (ATX-I, -II, and -III), and L-tenuazonic acid (TeA). Cleanup procedures of analytical methods for foods and foodstuffs include solvent partition, generally used for TeA, and solid-phase extraction columns for AOH, AME, and ATX-I. These Alternaria mycotoxins have been determined by TLC, GC, and more usually LC, mainly with ultraviolet detection, although fluorescence and electrochemical detection have also been used for Alternaria toxins other than TeA. A Zn2+ salt is usually added to the LC mobile phase for TeA. Recently, atmospheric pressure chemical ionization and electrospray LC/MS and LC–MS/MS have been applied to the determination and confirmation of AOH and AME in apple juice and other fruit beverages at sub ng/mL levels. Natural occurrences of AOH, AME, and in some cases other Alternaria toxins have been reported in various fruits, including tomatoes, olives, mandarins, melons, peppers, apples, and raspberries. They have been found also in processed fruit products such as apple juice, other fruit beverages and tomato products, wheat and other grains, sunflower seeds, oilseed rape meal, and pecans.
Determination of Ochratoxin A in Wine and Beer by Immunoaffinity Column Cleanup and Liquid Chromatographic Analysis with Fluorometric Detection: Collaborative Study
Authors: Visconti Angelo , Pascale Michelangelo , Centonze Gianluca ,   Collaborators, Anklam E , Betbeder A M , Brereton P , Burns G , Cagnina A , Chiappetta G , Creppy E E , Di Stefano R , Eklund E , Hald B , Herve I , Kakouri E , Larcher R , Majerus P , Medina B , Melotti F , Möller T , Moruno E G , Nuotio K , Pavanello F , Pietri A , Tricard C , van den Top H J , Versini G , Werner J , Wilson P 
Published: February 2020

Abstract
The accuracy, repeatability, and reproducibility characteristics of a liquid chromatographic method for the determination of ochratoxin A (OTA) in white wine, red wine, and beer were established in a collaborative study involving 18 laboratories in 10 countries. Blind duplicates of blank, spiked, and naturally contaminated materials at levels ranging from ≤0.01 to 3.00 ng/mL were analyzed. Wine and beer samples were diluted with a solution containing polyethylene glycol and sodium hydrogen carbonate, and the diluted samples were filtered and cleaned up on an immunoaffinity column. OTA was eluted with methanol and quantified by reversed-phase liquid chromatography with fluorometric detection. Average recoveries from white wine, red wine, and beer ranged from 88.2 to 105.4% (at spiking levels ranging from 0.1 to 2.0 ng/mL), from 84.3 to 93.1% (at spiking levels ranging from 0.2 to 3.0 ng/mL), and from 87.0 to 95.0% (at spiking levels ranging from 0.2 to 1.5 ng/mL), respectively. Relative standard deviations for within-laboratory repeatability (RSDr) ranged from 6.6 to 10.8% for white wine, from 6.5 to 10.8% for red wine, and from 4.7 to 16.5% for beer. Relative standard deviations for between-laboratories reproducibility (RSDR) ranged from 13.1 to 15.9% for white wine, from 11.9 to 13.6% for red wine, and from 15.2 to 26.1% for beer. HORRAT values were ≤0.4 for the 3 matrixes.
Determination of Cry9C Protein in Corn-Based Foods by Enzyme-Linked Immunosorbent Assay: Interlaboratory Study
Authors: Trucksess Mary W ,   Collaborators:, Artis T , Diaz C , Fernandez C , Harkin K , Layton D , Shillito R , Thomas F , Williams K , Yeung J 
Published: February 2020

Abstract
The performance of a commercially available enzyme-linked immunosorbent assay kit (Enviro-Logix) was assessed for the determination of Cry9C protein, which is produced by the genetically modified corn StarLink, in 8 types of corn-based foods (starch, refined oil, soft tortillas, tortilla chips, corn flakes, corn puffs, corn muffins, and corn bread) in an interlaboratory study involving 7 laboratories in the United States. The assay kit is a double antibody sandwich and is based on the specific interaction between antibody and antigen. The Cry9C protein analyte is sandwiched between 2 antibodies, one to capture the analyte and the other is conjugated to the enzyme, horseradish peroxidase. The enzyme uses tetramethylbenzidine/peroxide for color development. A strong acid stopping reagent is then used to change the color from blue to a stable yellow. The intensity of the color is proportional to the concentration of the Cry9C protein. In this study blind duplicates of control samples (blank material prepared from non- StarLink corn), spiked samples (blank material with the addition of Cry9C protein), and samples containing incurred analyte (products prepared with StarLink corn) were analyzed. Cry9C protein from 2 different sources was used to spike the food products. Cry9C protein produced and purified from a bacterial host was used to prepare spiked test samples at 2.72 and 6.8 ng/g. Cry9C protein from StarLink corn flour was used to prepare spiked samples at 1.97 ng/g. Average recoveries for samples spiked with corn flour Cry9C protein at 1.97 ng/g ranged from 73 to 122%, within-laboratory relative standard deviations (RSDr) ranged from 6 to 22%, and between-laboratories relative standard deviations (RSDR) ranged from 16 to 56%. Average recoveries for samples spiked with bacterial Cry9C protein at 2.72 and 6.8 ng/g ranged from 27 to 96% and from 32 to 113%, respectively; RSDr values ranged from 10 to 35%and from 7 to 38%, respectively; and the RSDR ranged from 28 to 84%and 15 to 75%, respectively. The incurred test samples were found to contain Cry9C protein at levels ranging from 0.8 to 3187 ng/g depending on the product, RSDr values ranged from 5 to 16% and RSDR values ranged from 11 to 71%. Results of the statistical analysis indicate that this method is applicable to the determination of Cry9C protein in the 8 types of collaboratively studied corn-based products containing Cry9C protein (from StarLink ) at levels of ≥2 ng/g.