Synthesis and characterization of bis nitrato[4-hydroxyacetophenonesemicarbazone) nickel(II) complex as ionophore for thiocyanate-selective electrode

Abstract

The PVC based-ion selective electrode viz., bis nitrato[4-hydroxyacetophenone semicarbazone] nickel(II) as an ionophore was prepared for the determination of thiocyanate ion. The ionophore was characterized by FT-IR, UV–vis, XRD, magnetic moment and elemental analysis (CHN). On the basis of spectral studies an octahedral geometry has been assigned. The best performance was obtained with a membrane composition of 31% PVC, 63% 2-nitrophenyl octylether, 4.0% ionophore and 2.0% trioctylmethyl ammonium chloride. The electrode exhibited an excellent Nernstian response to SCN− ion ranging from 1.0×10−7 to 1.0×10−1M with a detection limit of 8.6×10−8M and a slope of −59.4±0.2mV/decade over a wide pH range (1.8–10.7) with a fast response time (6s) at 25°C. The proposed electrode showed high selectivity for thiocyanate ion over a number of common inorganic and organic anions. It was successfully applied to direct determination of thiocyanate in biological (urine and saliva) samples in order to distinguish between smokers and non-smokers, environmental samples and as an indicator electrode for titration of thiocyanate ions with AgNO3 solution.