Abstract: In the supporting electrolyte containing KH₂PO₄ and K₂HPO₄ (pH = 7.0), 8-hydroxy-5- quinolinesulfonic acid (HQSA) can be adsorbed on the Hg electrode above -0.60 V (vs. Ag/AgCl electrode), thus the complex of Bi( Ⅲ ) with HQSA can also be adsorbed on the Hg electrode. The reduction peak of Bi( Ⅲ )-HQSAsystem E_p=-0.44 V) results from the reduction of Bi( Ⅲ ) into bismuth amalgam, belonging to a weakly adsorptive system of reactant. The electrochemical behaviour, especially the adsorptive properties of both HQSAand Bi( Ⅲ )-HQSA were studied by various methods. The reduction peak of Bi( Ⅲ )-HQSA can be used to determine trace amount of Bi( Ⅲ ) by linear sweep adsorptive stripping voltammetry. The peak hight is linearly proportional to the concentration of Bi( Ⅲ ) in the range of 5.0×10^-9-1.0×10^-6 mol/L. The detection limit of Bi( Ⅲ ) is 2.0× 10^-9 mol/L.

Key words: Bismuth, 8-Hydroxy-5-Quinolinesulfonic acid, Adsorptive stripping voltammetry