Epoxy - Graphite Tube Bulk-Modified with 2-Mercaptobenzothiazole as a Robust Electrode for the Preconcentration and Stripping Analysis of Hg(II)

Abstract

A novel method of fabricating a bulk-modified composite electrode is proposed. In this method, a preformed, porous graphite tube was impregnated with a modifier by thorough soaking in a solution containing the modifier. After drying, the modifier was sealed in place in the pores with epoxy. For the purpose of demonstrating the usefulness of the electrode, 2-mercaptobenzothiazole was chosen as the modifier and the modified electrode was used to preconcentrate mercury(II), followed by voltammetric stripping analysis. The fabricated electrode possessed good stability and had an extended lifetime. Precision for 10 consecutive differential pulse stripping experiments, for a 2 min preconcentration, gave relative standard deviations of 1.9% and 2.6% for Hg(II) concentrations of 1.00 × 10-6 and 1.00 × 10-8 M, respectively. Detection limit was estimated to be 3.0 × 10-9 M (S/N = 3, 3 min preconcentration). A certified aqueous sample, USEPA WP 386, was employed for method testing.