Polarographic determination of free antimony(III) in ammonium 5-tungsto-2-antimoniate

Abstract

A simple differential-pulse polarographic method for the determination of free antimony(III) in ammonium 5-tungsto-2-antimoniate (HPA23) is described. In Tris buffer (pH 7) antimony(III) gives a well defined reduction peak at –0.54 V which is clearly separated from the direct reduction of the HPA23. The limit of detection is about 0.005%m/m and the coefficient of variation is 12%(n= 18; 95% confidence level). HPA23 was found to be unstable in aqueous solution over the entire pH range.