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 Hg2+, Cu2+, Pb2+ and Cd2+ 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 Hg2+ concentration in the range from 1.0 μM to 80.0 μM, and with Cu2+, Pb2+ and Cd2+ 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 (Hg2+), 2.797 μA·μM−1·cm−2 (Cu2+), 5.203 μA·μM−1·cm−2 (Pb2+) and 1.390 μA·μM−1·cm−2 (Cd2+), respectively. The limits of detection for the four ions were estimated to be 0.0293 μM (Hg2+), 0.108 μM (Cu2+), 0.0619 μM (Pb2+) and 0.135 μM (Cd2+), 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.