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Determination of Hypoxanthine in the Presence of Copper by Adsorptive Stripping Voltammetry

American Journal of Analytical Chemistry 2014年第5期5卷 291-300页

作者： Percio Augusto Mardini Farias arnaldo aguiar castro Department of Chemistry Pontifícia Universidade Católica Rua Marquês de S&atilde o Vicente Rio de Janeiro Brazil Facultad Quimica Quimica Analitica Universidad de La Habana Havana Cuba

A stripping method for the determination of hypoxanthine in the presence of copper at the submicromolar concentration levels is described. The method is based on controlled adsorptive accumulation of hypoxanthine-copper at the thin-film mercury electrode followed by a fast linear scan voltammetric measurement of the surface species. Optimum experimental conditions were found to be the use of 1.0 × 10﹣3 mol·L﹣1 NaOH solution as electrolyte supporting, an accumulation potential of ﹣0.50 V and a linear scan rate of 200 mV·s﹣1. The response of hypoxanthine-copper is linear over the concentration ranges of 10 - 60 ppb. For an accumulation time of 30 minutes, the detection limit was found to be 250 ppt (1.8 × 10﹣9 mol·L﹣1). Adequate conditions for measuring the hypoxanthine in the presence of metal ions, xanthine, uric acid and other nitrogenated bases were also investigated. The utility of the method is demonstrated by the presence of hypoxanthine associated in ATP or ssDNA.

关键词： Hypoxanthine Determination Xanthine Uric Acid Copper Ion ATP ssDNA Thin-Film Mercury Electrode Fast Linear Scan Stripping Voltammetry

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Determination of the Antiretroviral Drug Zidovudine in Diluted Alkaline Electrolyte by Adsorptive Stripping Voltammetry at the Mercury Film Electrode

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American Journal of Analytical Chemistry 2011年第2期2卷 223-234页

作者： arnaldo aguiar castro Ricardo Queiroz Aucélio Nicolás Adrián Rey Eliane Monsores Miguel Percio Augusto Mardini Farias 不详

This paper describes a stripping method for the determination of zidovudine at the submicromolar concentration levels. This method is based on the controlled adsorptive accumulation of zidovudine at the thin-film mercury electrode, followed by a linear-sweep stripping voltammetry measurement of the surface species. Optimal experimental conditions include a NaOH solution of 2.0 × 10–3 mol●L–1 (sup-porting electrolyte), an accumulation potential of –0.30 V and a scan rate of 100 mV?s–1. The response of zidovudine is linear over the concentration range 0.01 - 0.08 ppm. After an accumulation time of 5 minutes, the detection limit was found to be 0.67 ppb (2.5 × 10–9 mol●L–1). More convenient methods to measure zidovudine concentration in the presence of the didanosine, acyclovir, nevirapine, lamivudine, and efavirenz, were also investigated. The presence of zidovudine together with ATP or ssDNA demonstrates the utility of this method.

关键词： Zidovudine Determination Antiviral Drugs Ssdna Thin-Film Mercury Electrode Stripping Voltammetry

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Biquinho pepper(Capsium chinense):Bioactive compounds,in vivo and in vitro antioxidant capacities and anti-cholesterol oxidation kinetics in fish balls during frozen storage

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Food Bioscience 2022年第3期47卷 512-523页

作者： Bárbara Jardim Mariano Vanessa Sales de Oliveira Davy William Hidalgo Chávez Rosane Nora castro Cristiano Jorge Riger Jéssica Sodré Mendes Marcelo da Costa Souza Alexandra Christine Helena Frankland Sawaya Geni Rodrigues Sampaio Elizabeth Aparecida Ferraz da Silva Torres Tatiana Saldanha Department of Food Technology Institute of TechnologyUniversity Federal Rural of Rio de JaneiroRodovia Br 465SeropédicaRJ23890-000Brazil Department of Chemistry Institute of ChemistryUniversity Federal Rural of Rio de JaneiroRodovia Br 465SeropédicaRJ23890-000Brazil Department of Biochemistry Institute of ChemistryUniversity Federal Rural of Rio de JaneiroRodovia Br 465SeropédicaRJ23890-000Brazil Department of Botany Institute of Biological Sciences and HealthUniversity Federal Rural of Rio de JaneiroRodovia Br 465SeropédicaRJ23890-000Brazil Faculty of Pharmaceutical Science University of CampinasUNICAMPCampinasSPBrazil Department of Nutrition School of Public HealthUniversity of São Paulo (USP)Ave.Dr.Arnaldo715São PauloSP01246-904Brazil

The present study reports bioactive constituents from biquinho pepper,such as carotenoids,capsaicinoids,and capsinoids,identified by UHPLC-MS.Biquinho pepper extract showed an antioxidant potential by DPPH(33.17±0.08%),ORAC(32.35±0.02μM TE/g),β-carotene/linoleic acid(55.80±1.30%),and FRAP(315.88±4.23μmol TE/g)assays.Additionally,in vivo antioxidant analyses demonstrated that the pepper extract(170μg/mL)decreased the damage promoted by H_(2)O_(2) in Saccharomyces cerevisiae cells.Fish balls were prepared using different concentrations of pepper(0.0%,0.5%,0.75%,1.0%)to investigate its antioxidant effect during frozen storage.Biquinho pepper effectively reduced the formation of cholesterol oxides and preserved essential fatty acids,mainly in samples containing 1.0%of pepper.Moreover,this treatment was more efficient than sodium erythorbate(p0.8).

关键词： Bioactive compounds Capsicum chinense Cholesterol oxides Frozen storage Natural antioxidants Unsaturated lipids

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