ABSTRACT
A sensitive stripping voltammetric procedure for trace measurement of thorium, based on the catalytic-adsorptive peak of the thorium-cupferron complex, is reported. Optimal experimental conditions include the use of 1mM BES buffer solution (pH 5.5), containing 20muM cupferron, an accumulation potential of -0.80 V (vs. Ag/AgCl), and a differential pulse potential scan. The resulting stripping procedure offers improved sensitivity over a previous stripping scheme for thorium. The limit of detection after 5 min preconcentration is 50 ng/l. (2 x 10(-10)M), the response is linear up to 8 x 10(-8)M, and the relative standard deviation at the 2.1 x 10(-8)M level is 4.4%. Possible interferences are evaluated.
ABSTRACT
The adsorptive collection of the aluminum complex with cupferron is exploited for developing a highly sensitive stripping procedure for trace aluminum. Optimal experimental conditions include the use of 2 x 10(-4)M cupferron in PIPES buffer (pH 7.0), an accumulation potential of -0.40 V and a linear potential scan. With controlled accumulation for 2 min, a detection limit near 30 ng/l. aluminum is obtained. The relative standard deviation (at 5 microg/l.) is 2.9%. Possible interferences are evaluated. The analytical performance compares favourably with that of early adsorptive stripping schemes for aluminum.
