COMBINED USE OF DIFFERENTIAL-PULSE ADSORPTIVE AND ANODIC-STRIPPING TECHNIQUES FOR THE DETERMINATION OF ANTIMONY(III) AND ANTIMONY(V) IN ZINC ELECTROLYTE

A knowledge of the concentration of both antimony(III) and antimony(V) is required in zinc plant electrolyte. In this paper, it is shown tha t an interference-free method to determine the low concentration of an timony in both oxidation states in zinc matrices is achieved by the co mbined use of differential pulse anodic stripping voltammetry (DPASV) after addition of concentrated hydrochloric acid (total antimony) and differential pulse adsorptive stripping voltammetry (DPAdSV) after add ition of dilute hydrochloric and chloranilic acid (antimony(III)). The antimony(V) concentration is therefore calculable from the difference in the DPASV and DPAdSV determinations. In principle, antimony(III) c ould be determined by DPASV and antimony(V) by DPAdSV. However, in zin c electrolyte, the antimony(III) DPASV method suffers from a small lev el of interference when antimony(V) is present, while the DPAdSV metho d for the determination of antimony(V) is significantly interefered wi th by the presence of antimony(III). Consequently, only the combined u se of both the DPASV and DPAdSV gives the required selectivity to achi eve a completely interference-free determination of antimony in each o xidation state in zinc plant electrolyte. (C) 1998 Elsevier Science B. V. All rights reserved.