An ion selective electrode for mercury(II) based on mercury(II) complex of poly(4-vinyl pyridine)

This study reports on the fabrication, characterization and utilization of the heterogeneous poly(Hg(II)-4-vinyl pyridine) membrane electrode. The electrode, with plasticiser tris(2-ethyl hexyl) phosphate, has a Nernstian response with slope of 30 ± 1 mV decade−1 in concentration range of 10−7–10−2 M Hg2+, and in solution of pH 3–4. It has response and life time of less than 25 s and more than 120 days, respectively. Limit of detection is at 0.5 × 10−7 M Hg2+. Interferences from other cations are not serious, except silver(I) at mercury(II) concentration less than 10−4 M. Analyses of water samples show that the proposed electrode agrees well with the standard method with correlation coefficient, R2, 0.9998. The electrode is also suitable as an indicator electrode in the potentiometric titration of Hg(II) with iodide.