Trace Detection of Mercury(II) Using Gold Ultra-Microelectrode Arrays

Abstract

The electroanalytical detection of trace mercury(II) at gold ultra-microelectrode arrays is reported. The arrays consist of 256 gold microelectrodes of 5 μm in diameter in cubic arrangements which are separated from their nearest neighbor by 100 μm. The array was utilized in nitric acid using linear sweep voltammetry where a linear response from mercury additions over the range 10 μg L−1−200 μg L−1 (10−8−10−6 M) was observed with a sensitivity and detection limit of 0.11 nC/μg L−1 and 3.2 μg L−1 (16 nM) respectively from using a deposition time of 30 s at −0.2 V (vs. SCE). This methodology was explored in 0.1 and 1 M chloride media over the mercury range 10 μg L−1−200 μg L−1 (5×10−8−10−6 M) where similar sensitivities of 0.087 nC/μg L−1 and 0.078 nC/μg L−1 were observed with an identical detection limit. The protocol is demonstrated to be useful for the determination of mercury for analysis of environmental water samples.