Inversvoltammetrische spurenbestimmung von Antimon(III) und Antimon(V) in aquatischen umweltproben nach selektiver extraktion

The biological activity of antimony depends on the oxidation state. The Sb(III) and Sb(V) states can be distinguished, even in the ng l^?1 range, by coupling extraction with ammonium pyrrlidenedithiocarbamate into methyl isobutyl ketone (APDC/MIBK), or N-benzoyl-N-phenylhydroxylamine (BPHA) into chloroform, with anodic stripping voltammetry (a.s.v.). After complex formation with APDC in acetate-buffered medium, Sb(III), but not Sb(V), is extracted into MIBK and quantified by a.s.v. Antimony(V) is quantified in the aqueous phase after removal of Sb(III) by extraction with BPHA into chloroform from the medium acidified with nitric acid. The applicability of the proposed separation/a.s.v. method is demonstrated for samples of rain, snow and water from a dredging operation. The stability of the two antimony species is examined for natural waters with Sb(III) and Sb(V) added; possibilities of stabilization are described. The precedures should be suitable for speciation of antimony in relatively unpolluted waters.