Highly Sensitive EQCM Sensor for Mercury Determination by Coupled Stripping Voltammetry

摘要

An electrochemical quartz crystal microbalance (EQCM) can be used as electrochemical strippingsensor for mercury (II) detection. Due to the frequency changes of EQCM electrode were used asanalytical signal instead of currents, the influence of interference current would not be considered. Toimprove the sensitivity and signal response range, a QCM electrode, modified with Nafion film andAu-nanoparticles (Au-NPs), was employed as a stripping detector for mercury (II) determination in 0.1M perchloric acid. The cooperation of Au-NPs and Nafion on the gold electrode surface provided anenvironment for the enhanced electrodeposition of mercury (II). The prepared sensor exhibited a widelinear response to mercury (II) in the concentration range of 3-300 nM (correlation coefficient of0.9968), with a detection limit of 0.15 nM. The Nafion film was placed between the Au-NPs and theQCM gold-based electrode, which prevented the direct deposition of mercury onto the QCM gold- based electrode surface, and resulted in the easier regeneration of composites modified electrodes. Onthe other hand, the roughness of electrode surface increased owing to the modification of Nafion film,which would provide much more area for the immobilization of Au-NPs.