Electrochemical Determination of Trace Amounts of Lead (Ⅱ) and Cadmium (Ⅱ) at a Calix[6]arene Modified Carbon Paste Electrode

An electrochemical method for the simultaneous determination of lead(Ⅱ) and Cadmium(Ⅱ) with a calix\arene modified carbon paste electrode (CPE) has been developed. Pb 2+ and Cd 2+ were accumulated at the surface of the modified electrode via formation of chemical complexes with calix\arene, and reduced at 1.40 V. During the following anodic potential sweep, reduced lead and cadmium were oxidized, and two well-defined striping peaks appeared at about -0.60 V and -0.84 V. Compared with a bare carbon paste electrode, the calix\arene modified CPE greatly improves the sensitivity of determining lead and cadmium. The stripping peak currents change linearly with the concentration of Pb 2+ 3.0×10 -8 -8.0×10 -6 mol\5L -1 and with that of Cd 2+ 6.0×10 -8 -1.0×10 -5 mol\5L -1 . The detection limits of Pb 2+ and Cd 2+ are found to be 8.0×10 -9 mol\5L -1 and 2.0×10 -8 mol\5L -1 , respectively. The modified carbon paste electrode was applied to determine trace levels of lead and cadmium in water samples. Comparing with that of atomic absorption spectrometry, the results suggests that the calix\arene modified CPE has great potential for the practical sample analysis.