Carbon paste electrodes modified with Bi 2 O 3 as sensors for the determination of Cd and Pb

Abstract

Carbon paste electrodes bulk-modified with Bi₂O₃ were used for the determination of Cd(II) and Pb(II). The best composition was 1% (wt%) Bi₂O₃ in the paste. The measurements were made by differential pulse voltammetry in the potential range from –1.2 V to –0.3 V. The peak potential of the reoxidation of Cd is –0.85 V, and of Pb –0.60 V vs. SCE. The lowest concentration that could be determined was 5 µg L^–1 of both metals (preconcentration time 240 s), the relative standard deviation was 3.5%–5.0% (four determinations). The correlation coefficient (r ²) of the calibration curves was 0.9966 (for Cd) and 0.9971 (for Pb). The Bi₂O₃-modified electrode could be used for the analysis of drinking water, mineral water and urine.