| A platinum disc microelectrode array and screen printed electrode (SPCE) were fabricated and it's application was studied.In chapter 2, the platinum disc microelectrode array was fabricated. The microelectrode array's electrochemical characters were study. It was used for the determination of trace levels of lead(Ⅱ) in synthetic and tea samples, by employing thin mercury film formed at the electrodes. Lead and mercury were deposited in-situ with chronoamperometry and stripped using square wave anodic stripping voltammetry. The stripping peak current is linearly with the concentration over the range of 0.2 35.0μg/L for lead ion. The detection limit (S / N = 3)is 0.05μg/L. The recovery is 86.0% 95.2%. In chapter 3, we employed disposable SPCE for the determination of trace mercury. SPCE is easily fabricated with low costs. The electrode offered a greater simplicity, because modification is unnecessary. In the experimental conditions, no reduction of other heavy metals has been observed show a high selectivity. Finally, the SPCE was applied to the determination of tea samples.In chapter 4, a new type of multi-walled carbon nanotubes (MWNTs) and Prussian blue (PB) co-modified screen-printed electrode (SPCE) has been fabricated for the detection of hydrogen peroxide. PB was electrodeposited on the surface of MWNTs-modified SPCE and MWNTs showed an obvious promotion for the redox reaction rates of hydrogen peroxide. Cyclic voltammetry and amperometric measurements were employed to demonstrate the feasibility of Prussian blue as a catalyst to determine hydrogen peroxide. This resulting sensor showed a wide linear range of amperometric responses to H2O2. The presence of dopamine, ascorbate and urate hardly affected the sensitive determination of H2O2.
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