ULTRASOUND ENHANCED ANODIC-STRIPPING VOLTAMMETRY USING PERFLUOROSULFONATED IONOMER-COATED MERCURY THIN-FILM ELECTRODES

The high mass transport caused by ultrasonic radiation in the preconce ntration of trace metal species in anodic stripping voltammetry (ASV), leads to an order of magnitude enhancement in sensitivity. A Non-coat ed mercury thin-film working electrode is placed in a specially design ed small-volume sonovoltammetric cell. The preparation and curing proc edure for the Nafion film on a glassy carbon electrode substrate as we ll as ultrasound enhanced mercury deposition through the Nafion him ar e optimized. The resulting electrode assembly is stable under ultrason ic irradiation. Optical microscopy observations show the formation of closely spaced mercury droplets of micrometer dimensions under the Naf ion film. The performance characteristics of ultrasound-enhanced ASV a t the Nafion-coated mercury thin-film electrode are studied in detail. The detection limit obtained for lead and cadmium test species is 3 x 10(-11) M (30 s preconcentration in the presence of ultrasound). A re lative standard deviation of 1.2% is obtained for repetitive determina tions of 10 nM Cd2+ (n = 9).