Enhanced stripping voltammetric response of Hg2+, Cu2+, Pb2+ and Cd2+ by ZIF-8 and its electrochemical analytical application

The zeolitic imidazolate framework ZIF-8 was synthesized and mixed with chitosan (CS) solution to obtain a homogeneous dispersion. Then the dispersion of ZIF-8 and CS (ZIF-8-CS) modified glassy carbon electrode is fabricated and utilized for stripping voltammetric analysis of Hg 2+ , Cu 2+ , Pb 2+ and Cd 2+ for the first time. The large surface area effect and strong enriching effect of the nanosized ZIF-8 to the four heavy metal ions contribute to significantly enhance analytical signals. Under the optimum conditions, the stripping peak current densities linearly increased with Hg 2+ concentration in the range from 1.0   μM to 80.0   μM, and with Cu 2+ , Pb 2+ and Cd 2+ concentrations in the range from 1.0   μM to 100.0   μM. The analytical sensitivity for the four ions are estimated to be 14.20   μA·μM −1 ·cm −2 (Hg 2+ ), 2.797   μA·μM −1 ·cm −2 (Cu 2+ ), 5.203   μA·μM −1 ·cm −2 (Pb 2+ ) and 1.390   μA·μM −1 ·cm −2 (Cd 2+ ), respectively. The limits of detection for the four ions were estimated to be 0.0293   μM (Hg 2+ ), 0.108   μM (Cu 2+ ), 0.0619   μM (Pb 2+ ) and 0.135   μM (Cd 2+ ), respectively. The ZIF-8 based modified electrode also presented excellent anti-interference ability, and good reliability for monitoring the four ions in real water samples.