Electrochemical determination of lead(II) using a montmorillonite calcium-modified carbon paste electrode

Utilizing the fascinating properties of montmorillonite calcium (MMT-Ca), such as huge cationic exchange capacity, strong adsorptive ability, high chemical and mechanical stability, an MMT-Ca modified carbon paste electrode (CPE) was constructed for the sensitive determination of Pb²⁺. In 0.01 mol·L⁻¹ HCl, Pb²⁺ was firstly exchanged and accumulated on an MMT-Ca modified CPE surface and secondly reduced to Pb at −0.90 V. In the following potential sweep from −0.90 to −0.50 V, reduced Pb was oxidized, resulting in an obvious stripping peak at −0.58 V. After optimizing the parameters, such as determining medium, content of MMT-Ca, accumulation potential and time, an electrochemical method was developed for the analysis of Pb²⁺. Compared with bare CPE, the MMT-Ca modified CPE significantly enhances the sensitivity of Pb²⁺ analysis. The limit of detection is evaluated to be 6.0 × 10⁻⁹ mol L⁻¹ Pb²⁺. Finally, this method was successfully employed to determine trace levels of Pb²⁺ in water samples. The first two authors contribute equally do this work