Navegando por Autor "Saczk, Adelir Aparecida"
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Item Sensitive multiresidue quantification of procymidone and tebuthiuron on carbon paste electrode by differential-pulse voltammetry(Revista de Engenharia Química e Química, 2016-08-02) Fidélis, Meilene Ribeiro; Okumura, Leonardo Luiz; Silva, Ástrea Filomena de Souza; Gurgel, Alexandre; Saczk, Adelir AparecidaQualitative electrochemical characterization of procymidone (PRO) and tebuthiuron (TBH) was carried out by cyclic voltammetry using a carbon paste electrode. The studies suggest that analyte mass transfer is controlled by diffusion, and that oxidation of PRO and TBH occurs by means of irreversible electronic transfer of one electron. Oxidation of PRO and TBH occurs close to +0.820 V and +1.075 V (vs. Ag|AgCl, KCl 3.0 mol L^ -1 ), respectively, in a 0.10 mol L^ –1 KOH solution as supporting electrolyte. Quantitative analyses were carried out by differential-pulse voltammetry, a technique which is more sensitive and selective. Detection and quantification limits were determined for PRO and TBH in the absence of matrix, in a potable-water matrix, and in a nonpotable-water matrix, for which the ranges of reproducibility, intermediate precision and recovery rates were (1.01 and 4.20 %), (4.08 and 9.56 %), and (90.6 and 115 %) for PRO, and (1.59 and 3.92 %), (4.84 and 7.46 %), and (91.3 and 119 %), for TBH, respectively. The results indicate that the new method is selective, simple and cheap to simultaneously quantify PRO and TBH in water samples.Item Voltammetric determination of Δ9 -THC in glassy carbon electrode: An important contribution to forensic electroanalysis(Forensic Science International, 2012-09-10) Saczk, Adelir Aparecida; Balbino, Marco Antonio; Menezes, Matheus Manoel Teles de; Eleotério, Izabel Cristina; Okumura, Leonardo Luiz; Tristão, Heloı́sa Maria; Oliveira, Marcelo Firmino deA new voltammetric method for the determination of Δ^9-tetrahydrocannabinol (Δ^9-THC) is described. The voltammetric experiments were accomplished in N-N dimethylformamide/water (9:1, v/v), using tetrabutylammonium tetrafluoroborate (TBATFB) 0.1 mol/L as supporting electrolyte and a glassy carbon disk electrode as the working electrode. The anodic peak current was observed at 0.0 V (vs. Ag/AgCl) after a 30 s pre-concentration step under an applied potential of −1.2 V (vs. Ag/AgCl). A linear dependence of Δ^9-THC detection was obtained in the concentration range 2.4–11.3 ng/mL, with a linear correlation coefficient of 0.999 and a detection limit of 0.34 ng/mL. The voltammetric method was used to measure the content of Δ^9-THC in samples (hemp and hashish) confiscated by the police. The elimination of chemical interferences from the samples was promptly achieved through prior purification using the TLC technique, by employing methanol/water (4:1, v/v) as the mobile phase. The results showed excellent correlation with results attained by HPLC.Item Voltammetric determination of ∆^9 -THC in glassy carbon electrode: An important contribution to forensic electroanalysis(Forensic Science International, 2012-09-10) Okumura, Leonardo Luiz; Balbino, Marco Antonio; Menezes, Matheus Manoel Teles de; Eleoterio, Izabel Cristina; Saczk, Adelir Aparecida; Tristao, Heloısa Maria; Oliveira, Marcelo Firmino deA new voltammetric method for the determination of ∆^9- tetrahydrocannabinol (∆^9-THC) is described. The voltammetric experiments were accomplished in N-N dimethylformamide/water (9:1, v/v), using tetrabutylammonium tetrafluoroborate (TBATFB) 0.1 mol/L as supporting electrolyte and a glassy carbon disk electrode as the working electrode. The anodic peak current was observed at 0.0 V (vs. Ag/AgCl) after a 30 s pre-concentration step under an applied potential of À1.2 V (vs. Ag/AgCl). A linear dependence of ∆^9-THC detection was obtained in the concentration range 2.4–11.3 ng/mL, with a linear correlation coefficient of 0.999 and a detection limit of 0.34 ng/mL. The voltammetric method was used to measure the content of ∆^9-THC in samples (hemp and hashish) confiscated by the police. The elimination of chemical interferences from the samples was promptly achieved through prior purification using the TLC technique, by employing methanol/water (4:1, v/v) as the mobile phase. The results showed excellent correlation with results attained by HPLC.