Analytical Sciences

Thiocyanate Ion-selective PVC Membrane Electrode Based on N,N′-Ethylene-bis(4-methylsalicylidineiminato)nickel(II)

M. MAZLOUM ARDAKANI,* M. JAMSHIDPOUR,** H. NAEIMI,** and L. MORADI**

*Chemistry Department, Yazd University, Yazd, Iran
**Chemistry Department, Kashan University, Kashan, Iran

A highly selective poly(vinyl chloride) (PVC) membrane electrode based on an N,N′-ethylene-bis(4-methyl-salicylidineiminato) nickel(II) [Ni(EBMSI)] complex as a carrier for a thiocyanate-selective electrode is reported. The influences of the membrane composition, pH and possible interfering anions were investigated based on the response properties of the electrode. The electrode exhibited a good Nernstian slope of -58.9 ± 0.7 mV decade^-1, over a wide pH range of 3.5 - 8.5 and a linear range of 1.0 × 10^-6 - 1.0 × 10^-1 M for thiocyanate. The detection limit of electrode was 3.1 × 10^-7 M SCN^-. The selectivity coefficients determined by a fixed interference method (FIM) indicate that a good discriminating ability towards the SCN^- ion compared to other anions. The proposed sensor had a fast response time of about 5 - 15 s and could be used for at least 3 months without any considerable divergence in the potential. It was applied as an indicator electrode in the titration of thiocyanate with Ag⁺ and in the potentiometric determination of thiocyanate in saliva and urine samples.

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