Abstract: The anion response characteristics of transition metal chelates of a new Schiff base was systematically investigated in this paper. The results show that the electrode response characteristics have close relationship with the properties of the central metals, the electrodes based on the Mn(Ⅱ) chelate exhibited an excellent potentiometric response and selectivity towards thiocyanate. The linear response range of the electrode was (0.1~4.3)×10^-6 mol/Lwith a slope of-58.0 mV/dec., the anti Hofmeister selectivity pattern was: SCN^->I^->Sal^->PhCO₂^->ClO₄^->NO₂^->Br^->Ac^->NO₃^->Cl^-. The response mechanism was investigated by A.C. impedance and the effect of charged additives on the response characteristics and selectivity of the electrodes. It can be concluded that the electrodes exhibited Nernstian response to thiocyanate via a neutral carrier-based mechanism. The novel electrodes have advantages of being fast, accurate and stable, and can be used for the determination of thiocyanate in actual samples.

Key words: Anion-selective electrodes, Thiocyanate, Neutral carriers