DIFFERENTIAL PULSE ANODIC STRIPPING VOLTAMMETRIC DETERMINATION OF SELENIUM(IV) AT A GOLD ELECTRODE MODIFIED WITH 3,3′-DIAMINOBENZIDINE.4HCL-NAFION

摘要

Differential pulse anodic stripping voltammetric Analysis (DPASVA) of selenium(IV) using a gold electrode modified with 3,3′-diaminobenzidine.4HCl-nafion (GEMDN) has been studied. Various parameters (electrolyte, deposition time, pulse duration, pulse amplitude, etc.) affecting the Se(IV) determination were examined. Selenium(IV)was determined in an aqueous HClO4 (0.2M) medium of pH 0.22 at an accumulation potential of -200 mV and an accumulation time of 200 s. Under the optimum conditions, liner calibration graph, Ip=f(CSe4+), was obtained in the concentration ranges of 5x10-9M (0.3948 ng.mL-1) to 2x10-6M (157.92 ng.mL-1) with relative standard deviations (RSD).4.6%, and the detection limit was 0.06 ng.mL-1. This method showed a good accumulation efficiency for selenium and good resistance to interferences from metal ions as well as those associated with selenium in pharmaceuticals. The results for the determination of Se4+using GEMDN were more sensitive and accurate than that obtained using bare gold electrode; the sensitivity was increased about 20000 times