A voltammetric sensor for simultaneous determination of lead,cadmium and zinc on an activated carbon fiber rod

In this work, a simple, low cost and sensitive voltammetric sensor was developed for the simultaneous detection of lead (Pb²⁺), cadmium (Cd²⁺), and zinc (Zn²⁺) ions based on a disposable carbon fiber rod (CFR). The important factors to enhance the sensing property were creation of a clean surface by dealing with CFR at a high potential and electrochemical deposition of bismuth (Bi) film to improve the accumulation of heavy metal ions. The morphology and conductivity of such activated CFR was characterized by scanning electron microscopy and electrochemical impedance spectroscopy, respectively. In terms of application, differential pulse anodic stripping voltammetry (DPASV) was employed for the simultaneous detection of Pb²⁺, Cd²⁺, and Zn²⁺ on Bi film-coated activated CFR.Experimental parameters, such as the pH value of buffer solution, stirring speed and enrichment factors were optimized. Under optimal conditions, the DPASV peak currents showed good linear relationships with Pb²⁺, Cd²⁺ and Zn²⁺ concentrations in the range of 0.5–2.25 μg/L, 0.5-4.0 μg/L and 1.0–4.0 μg/L with detection limits of 0.1, 0.3 and 1.0 μg/L (S/N = 3), respectively. Finally, the proposed analysis system was successfully utilized for the simultaneous detection of Pb²⁺, Cd²⁺, and Zn²⁺ contents in rice samples. This study indicated that Bi film-coated activated CFR based DPASV sensor can be a promising and reliable tool for rapid analysis of emergency pollution affairs of heavy metal ions in food.