BISMUTH-ANTIMONY FILM ELECTRODE FOR STRIPPING VOLTAMMETRIC DETERMINATION OF TRACE CADMIUM AND LEAD IN THAI RICE WINE

Abstract

Stripping analysis was proposed for the voltammetric determination of trace cadmium and lead in local rice wine alcoholic beverages. A bismuth-antimony film electrode (Bi-SbFE) was employed for accumulative preconcentration of trace metals by adding 4 mg L-1 of bismuth and 1 mg L-1 of antimony directly to the sample solution and simultaneously depositing bismuth, antimony, and trace cadmium and lead target metals on the glassy carbon electrode by applying a fixed potential of –1.1 V versus the Ag/AgCl reference electrode for 300 s. Pre-treatment parameters for mineralization of the sample were optimized using the wet acid digestion procedure. Under the optimum conditions, linear calibration graphs ranging 20-200 µg L-1 for Cd and Pb were obtained with detection limits of 0.22 and 0.62 µg L-1 and limits of quantitation 0.73 and 2.07 µg L-1, respectively. Reproducibility values for seven replicate analyses of 50 µg L-1 Cd and Pb were 3.6 and 3.3%, respectively. The developed method was successful for Cd and Pb analyses in Thai rice wine samples and results were validated by the flame atomic absorption spectrometric method. Most samples were not contaminated with Cd and Pb. The amount of Cd contaminants in only one of rice wine sample was still lower than the maximum permitted level of Cd in wine.