Highly efficient electrocatalytic vapor generation of methylmercury based on the gold particles deposited glassy carbon electrode: A typical application for sensitive mercury speciation analysis in fish samples

摘要

A gold particle deposited glassy carbon electrode (Au/GCE) was first used in electrochemical vapor generation (ECVG) technology and demonstrated to have excellent catalytic property for the electrochemical conversion process of aqueous mercury, especially for methylmercury (CH3Hg+), to gaseous mercury. Systematical research has shown that the highly consistent or distinct difference between the atomic fluorescence spectroscopy signals of CH3Hg+ and Hg2+ can be achieved by controlling the electrolytic parameters of ECVG. Hereby, a new green and accurate method for mercury speciation analysis based on the distinguishing electrochemical reaction behavior of Hg2+ and CH3Hg+ on the modified electrode was firstly established. Furthermore, electrochemical impedance spectra and the square wave voltammetry displayed that the ECVG reaction of CH3Hg+ may belong to the electrocatalytic mechanism. Under the selected conditions, the limits of detection of Hg2+ and CH3Hg+ are 5.3 ng L-1 and 4.4 ng L-1 for liquid samples and 0.53 pg mg(-1) and 0.44 pg mg(-1) for solid samples, respectively. The precision of the 5 measurements is less than 6% within the concentration of Hg2+ and CH3Hg+ ranging from 0.2 to 15.0 mg L-1. The accuracy and practicability of the proposed method was verified by analyzing the mercury content in the certified reference material and several fish as well as water samples. (C) 2018 Elsevier B.V. All rights reserved.