Catalytic Polarographic Determination of Stibium(Ⅲ)

A stable complex between Sb(Ⅲ) with cupferron was formed in 0.20 mol·L-1 HCl solution, and a sensitive catalytic polarographic wave of this complex was observed at the potential of -0.38 V (vs.SCE) in the presence of KBrO3. Based on this fact, a method of catalytic polarography for the determination of Sb(Ⅲ) was proposed. Linear relationship between values of 2nd derivative of peak current and concentration of Sb(Ⅲ) was kept in the range of 4.8×10-9 to 3.6×10-6mol·L-1 with detection limit (3S/N) of 1.2×10-9mol·L-1. It was found that the polarographic wave was an adsorption catalytic wave, its electrode process was an irreversible reduction process, and the number of electron transfer was 3. The proposed method was used in the determination of traces of antimony in water samples, giving results obtained in consistency with those obtained by AAS. Values of recovery and RSD′s (n=6) found were in the ranges of 94.2%-106% and 2.5%-3.2% respectively.