Stripping Valtammetric Determination of Bismuth(Ⅲ) with Carboxylated Multi-walled Carbon Nanotubes Modified Carbon Paste Electrode

A carboxylated multi-wall carbon nanotubes (MWCNT-COOH) modified carbon paste electrode (CPE) was prepared by doping MWCNT-COOH on the surface of CPE. In the determination of Bi3+-ion, the test solution in 0.1 mol·L-1 HCl was pretreated by pre-enrichment for 120 s at -500 mV, to have the Bi3+-ion complexed with 1-(4-sulfo-phenyl)-3-［4-(phenylazo)-phenyl］-triazene (SPAPT). Bismuth ion in the complex was then stripped from the electrode by stripping voltammetry by scanning in the range from -500 to 500 mV, and the oxidation peak potential of bismuth ion was observed at -32 mV, where linear relationship between values of peak current of Bi3+-ion and its concentration was obtained in the range of 1.0×10-9-4.0× 10-7mol·L-1. Detection limit (3S/N) of the method found was 3.0×10-10mol·L-1.