Abstract

 PW₁₂O₄₀³⁻ (PW₁₂) supported on the surface of silica gel derivatized by 3-aminopropyl(triethoxy)silane (devoted briefly as SiNH₃PW₁₂) was synthesized and used as bulk modifier to fabricate a renewable three-dimensional chemically modified electrode. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry. There is an ionic bonding character between PW 12 and the surface amino groups of modified silica, which greatly improves the stability of SiNH 3 PW 12 -modified carbon paste electrode due to insolubility of silica gel in water. The SiNH₃PW₁₂ bulk-modified carbon paste electrode not only maintains the electrochemical activity of PW₁₂, but also exhibits remarkable advantages of renewability, as well as simple preparation and inexpensive material. The modified electrode offers an excellent and stable electrocatalytic response for the reduction of IO₃⁻ and hydrogen peroxide. The SiNH₃PW₁₂-CPE is successfully applied as an electrochemical detector to monitor IO₃⁻ in flow injection analysis (FIA). The catalytic peak current was found to be linear with the IO₃⁻ concentration in the range 5 × 10 − 6 to 1 × 10 ⁻³ mol L⁻¹ . The detection limit of the proposed method was found to be 3.1 × 10 ⁻⁶ mol L⁻¹ for IO₃⁻ determination.