DETERMINATION OF ANTIBILHARZIAL ANTIMONY COMPOUNDS BY DIRECT-CURRENT,DIFFERENTIAL-PULSE, SQUARE-WAVE AND ALTERNATING-CURRENT ANODIC-STRIPPING VOLTAMMETRY

A simple, rapid and sensitive method has been developed for the determ ination of Sb(III) in five antimonial antibilharzial drugs using anodi c stripping voltammetry. The method is based on the reduction of Sb(II I) on the HMDE, followed by a selected mode of oxidative sweep, i.e. d irect current, differential pulse, square-wave or first harmonic alter nating current sweep, using 2 mol/L HCl as a supporting electrolyte. V oltammograms for various sample concentrations in the range 3-47 ppb S b(III) were recorded and the respective calibration graphs constructed . To overcome the expected effect of adsorption of surface active orga nic compounds on the mercury drop, the standard addition technique of Sb2O3 solution was applied to calculate the recoveries of all the test ed antimonials. The method gave reproducible results within 2% and the limit of detection for all measurement modes was 3 ppb. SW and AC mod es seem to achieve lower detection limits than the other two modes. Th e four modes proved to be of equal accuracy and precision.