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Abstract: A highly selective and sensitive carbon paste electrode modified with multi-walled carbon nanotubes and 4-[1-(4-methoxyphenyl) methylidene]-3-methyl-5-isoxazolone was used for accumulation and determination of trace amounts of bismuth using the differential pulse anodic stripping voltammetric method. The analytical procedure consisted of a closed-circuit accumulation step onto the modified carbon paste electrode. An anodic peak related to the oxidation of accumulated Bi(0) on the electrode surface was observed at about −0.05V. The calibration curve was linear in the range of 1–400μgL−1. The limit of detection was 0.2μgL−1 and the relative standard deviations for seven replicated determinations at 30, 100 and 300μgL−1 of bismuth were 3.6, 2.4 and 1.6%, respectively. The modified electrode was applied for the determination of bismuth in pharmaceutical, biological and several water samples. The accuracy and precision of results were comparable to those obtained by the graphite furnace atomic absorption spectroscopy method. [Copyright &y& Elsevier]

In the present study, a carbon paste electrode chemically modified with gold nanoparticles was used as a sensitive electrochemical sensor for determination of eugenol. The differential pulse voltammetric method was employed to study the behavior of eugenol on this modified electrode. The effect of variables such as percent of gold nanoparticles, pH of solution, accumulation potential and time on voltammogram peak current were optimized. The proposed electrode showed good oxidation response for eugenol in 0.1 mol L − 1 phosphate buffer solution (pH 8) and the peak potential was about + 285 mV (vs. Ag/AgCl). The peak current increased linearly with the eugenol concentration in the range of 5–250 μmol L − 1 . The detection limit was found to be 2.0 μmol L − 1 and the relative standard deviation was 1.2% (n = 7). The effect of interferences on the eugenol peak current was studied. The method has been applied to the determination of eugenol in different real samples, spiked recoveries were in the range of 96%–99%. [ABSTRACT FROM AUTHOR]