Simultaneous, Selective and Highly Sensitive Voltammetric Determination of Lead, Cadmium, and Zinc via Modified Pencil Graphite Electrodes

Pencil graphite electrode (PGE) modified with MWCNT and Bi3+ (MWCNT/Bi/PGE) was utilized in simultaneous analysis of Pb2+, Cd2+, and Zn2+. Surface and electrochemical characteristics of MWCNT/Bi/PGE were investigated via SEM, cyclic voltammetry, electrochemical impedance spectroscopy, and FTIR measurements. Even though modification with MWCNT did not improve the electroactive surface area, it significantly decreased the charge transfer resistance. Furthermore, modification with Bi3+ significantly increased the sensitivity. Finally, MWCNT/Bi/PGE exhibited the highest sensitivity and reproducibility compared to PGE and PGE modified with only MWCNT. MWCNT/Bi/PGE provided LOD values of 0.27, 0.43, and 1.63 mu g L-1, and linear ranges of 1-80, 5-80, and 10-80 mu g L-1 for Pb2+, Cd2+, and Zn2+, respectively. Proposed modification method offers effective electroanalytical performance with low time consumption and cost for the analyst.