| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 218748 | Journal of Electroanalytical Chemistry | 2014 | 6 Pages |
•A simple on-line medium exchange was achieved for elimination of the chloride effect.•Two-step deposition potentials can be applied to the subsequently flowing solutions.•The in situ Au-SPCE can be renewed and used in a long term analysis.•SI-ASV can be used to obtain high sensitivity.•The proposed method can be applied to chloride-rich sample analysis with good accuracy.
A computer-controlled system, included a sequential injection system and an electrochemical detector, was developed for the determination of mercury(II) ion (Hg2+) concentrations. The screen-printed carbon electrode (SPCE), a well-known low-cost electrode, was modified by overlaying in situ with a gold film (Au-SPCE). Square wave anodic stripping voltammetry (SWASV) using the Au-SPCE was performed with a two-step deposition potential of an initial −0.5 V vs Ag/AgCl for the preparation of the gold film and then a deposition potential of +0.2 V vs Ag/AgCl for the preconcentration of mercury. An on-line medium exchange method was included in the injection step to reduce the effect of chloride ions, whilst a solid phase extraction cartridge was used to remove interference for copper(II) ions. The flow pattern of the sequentially injected solutions with the synchronized two-step deposition potentials did not significantly affect the detection of Hg2+. Square wave parameters of a 4 mV step potential, 150 Hz frequency and 30 mV amplitude gave an optimal Hg2+ detection sensitivity with a limit of detection of 0.22 μg L−1 (sample volume of 0.9 mL) without any significant interference effect. This method was successfully applied to determine Hg2+ concentrations in real water samples, including in the chloride-rich samples of sea water and table salt, with very good accuracy (recovery in the range of 96.0–101%).
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