Anodic stripping voltammetric determination of Cd2+ and Pb2+ using interpenetrated MWCNT/P1,5-DAN as an enhanced sensing interface

Abstract

Square wave anodic stripping voltammetric detection of Cd2+ and Pb2+ was carried out on sputtered planar platinum electrodes, modified with interpenetrated multiwalled carbon nanotubes/poly(1,5-diaminonaphthalene) (MWCNT/P1,5-DAN) as a sensing interface. Electrochemical behavior of the sensor was investigated by cyclic and square wave voltammetry. Key parameters affecting sensor performance such as P1,5-DAN film thickness, deposition potential, and time were optimized. The sensor exhibited linear responses to Cd2+ and Pb2+ concentrations ranging from 4 to 150 μg L−1. Under optimized conditions (five scan cycles, −1.2-V deposition potential, 420-s deposition time), the limits of detection were estimated to be around 3.2 and 2.1 μg L−1 for Cd2+ and Pb2+, respectively. The successive addition of Na+, Ca2+, Zn2+, Fe2+, Al3+, Cu2+ (each 1.0 mg L−1) and Cl−, Br−, SO4 2− (each 10.0 mg L−1) to 100-μg L−1 Pb2+ acetate buffer solution did not interfere with stripping peak current. Thus, modified MWCNT/P1,5-DAN electrode could be used as a good alternative to conventional mercury electrode for anodic stripping voltammetric determination of Cd2+ and Pb2+. The sensitivity, simplicity, ecosafety, and convenience of the suggested MWCNT/P1,5-DAN electrode were very competitive with respect to other methods such as atomic absorption spectrometry and anodic stripping voltammetry with hanging drop mercury electrodes. This sensing interface was applied to the determination of Pb2+ and Cd2+ contents in river water samples, and the results were quite corresponding to the value obtained by atomic absorption spectrometry. Therefore, a new type of “green electrode material,” MWCNT/P1,5-DAN, can potentially be extended to other electroanalytical applications.