Amperometric detection studies of poly-o-phenylenediamine film for the determination of electroinactive anions in ion-exclusion chromatography

Abstract

An amperometric detector based on the chemical modification of poly-o-phenylenediamine (P-OPD) on a gold electrode was successfully used for the determination of electroinactive anions (SO₄²⁻, Cl⁻, NO₃⁻, F⁻, CH₃COO⁻ and PO₄³⁻) by single-column ion-exclusion chromatography. All of the anions were detected conveniently and reproducibly in a linear concentration range of 1.0 × 10⁻⁵–5.0 × 10⁻³ mol L⁻¹. The detection limits of the anions were 2.10 × 10⁻⁶ mol L⁻¹ for SO₄²⁻, 2.47 × 10⁻⁶ mol L⁻¹ for Cl⁻, 3.53 × 10⁻⁶ mol L⁻¹ for NO₃⁻, 3.41 × 10⁻⁶ mol L⁻¹ for F⁻, 5.82 × 10⁻⁶ mol L⁻¹ for CH₃COO⁻ and 3.86 × 10⁻⁶ mol L⁻¹ for PO₄³⁻ at a signal-to-noise ratio of 3. The proposed method was successfully applied to the analysis of rainwater and river water samples. The electrode was stable during a 2 week period of operation with no evidence of chemical or mechanical deterioration.