Highly selective PVC-membrane electrodes based on Co(II)-salen for determination of nitrite ion

Abstract

A cobalt(II) derivative was used as a suitable ionophore for the preparation of a polymeric membrane nitrite-selective electrode. The electrode reveals a Nemstian behavior over a very wide NO2-NOf ion concentration range (1.0 x 10-6 - 1.0 x 10-1 M) and a very low detection limit (5.0 x 10-7 M). The potentiometric response is independent of the pH of solution in the pH range 4.0 - 9.5. The electrode shows advantages such as low resistance, fast response and, most importantly, good selectivity relative to a wide variety of inorganic and organic anions. In fact, the selectivity behavior of the proposed NO2 ion-selective electrode shows great improvements compared to the previously reported electrodes for nitrite ion. The proposed electrodes could be used for at least 2 months without any significant changes in potentials. The electrode was successfully applied to the determination of nitrate ion concentrations in sausage and milk samples.