Trace determination of Hg(II) in human saliva using disposable electrochemically pretreated graphite pencil electrode surfaces

An electrochemically pretreated graphite pencil electrode (PGPE) was designed to assay trace levels of Hg(II) in human saliva. The GPE was pretreated in 0.1 mol/L nitric acid by cycling the potential between –1.6 and –0.6 V for 60 cycles at a scan rate of 50 mV/s. The effects of pretreatment conditions, including media constituents, pH, and various electrochemical techniques and parameters, were analyzed and optimum conditions determined. Square wave anodic stripping voltammetry (SWASV) was used for the determination of Hg(II). The calibration curve obtained under optimum conditions showed that the linear range of the PGPE was from 10.0 × 10^–9 mol/L to 175.0 × 10^–9 mol/L with a detection limit of 3.0 × 10^–9 mol/L (S/N = 3). Relative to non-pretreated GPE surfaces, electrochemical pretreatment improved the electrochemical performance of GPE surfaces in detecting Hg(II). The present analytical method was used to measure Hg(II) released from dental amalgam in human saliva.