Highly Selective PVC-Membrane Electrodes Based on Co(II)-Salen for Determination of Nitrite Ion

A cobalt(II) derivative was used as a suitable ionophore for the preparation of a polymeric membrane nitrite-selective electrode. The electrode reveals a Nernstian behavior over a very wide NO2- ion concentration range (1.0 × 10-6 - 1.0 × 10-1 M) and a very low detection limit (5.0 × 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.