Method development for determination arsenic and mercury by sequential injection-anodic stripping voltammetry using gold film electrode

Abstract

This dissertation reported on the method development for the determinations of arsenic (As) and mercury (Hg) by sequential injection (SI) coupled with anodic stripping voltammetry (ASV) using gold-modified screen-printed Carbon electrodes (Au-SPCEs). An SI system is a very versatile automated flow-based system with very with very good precision and robustness. It has been developed to de compatible with numerous detection devices. An electrochemical detection called ASV is one of powerful techniques for metal detection due to its high sensitivity and selectivity, therefore, the combination of SI and ASV has been developed for the determination of highly toxic metals such as As and Hg using Au-SPCE, SPCE, which is well-printing as an inexpensive electrode, can be prepared in our laboratory by screen-printing technology, and the modification of Au on the electrode surface was performed by electrochemical deposition from Au(III) solution under a computer-controlled procedure via SI system. The conditions for the determinations of As and Hg by SI-ASV using the Au-SPCE have been optimized. Besides, the additional methods for efficient uses of the Au-SPCE were attentively investigated such as a renewal of Au-SPCE and a preservation of the modified Au on SPCE with a long-lasting property. Under the optimal conditions, the speciation of As (III) and As(V) has been achieved by SI-ASV using the long-lasting Au-SPCE with the detection limits of 0.03 µg/L for As(V), whereas Hg(II) can be determined by renewable Au-SPCE with the detection limit of 0.22 µg/L. Furthermore, this developed method has successfully determined As(III), As(V) and Hg(II) in real samples with high accuracy.