Trace analysis of antimony (III) and antimony (V) by adsorptive stripping voltammetry

A sensitive and selective adsorption stripping voltammetric (AdSV) method for the determination of antimony using chloranilic acid (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) as complexing reagent is described. The conditions under which its species. of both oxidation states, Sb(III) and Sb(V), can be detected have been established. Sb(III) can be adsorbed onto the hanging mercury drop electrode (HMDE) using an accumulation potential of +100mV from hydrochloric acid (pH = 3.0) solution. Sb(V) can be determined using an accumulation potential of - 500 mV in HCl (pH = 1.0) solution. The peak potentials in the stripping voltammograms are - 400 mV for Sb(III) and - 140 mV for antimony (V). The detection limits are 210 ng/L for Sb(III) with 5 min pre-concentration and 560 ng/L for Sb(V) with 10 min pre-concentration. The method is applicable to the trace analysis and speciation of antimony in water samples and phosphoric acid.