Determination of nitrite in environmental samples using chemically modified carbon paste electrode based on new Co(III)-benzopyran-4-one Schiff Base complex

Abstract

Nitrite chemically modified carbon paste electrode based on Co(III)-benzopyran-4-one Schiff base complex is described. The electrode revealed a Nernstian response over a wide nitrite ion concentration range (9.1×10–6–1.5×10–2 mol·L–1). The detection limit of the sensor is 7.0×10–6 mol·L–1. The best performance was obtained with a paste composition of 4 % Co(III)-benzopyran-4-one Schiff base, 2 % cetylpyridinium chloride (CPC), 42 % graphite, and 52 % dibutyl-butyl phosphonate (DBBP). The potentiometric response of the sensor is independent of the pH of solution in the pH range of 3.0–8.5. The electrode exhibits a very fast response time reaching to 20 s and good selectivity over a variety of common inorganic anions, including Cl–, Br–, NO3–, F–, SO4 2–, CO3 2–, S2–, HPO4 2–, S2O3 2–, and CH3COO–. The selectivity behavior of the proposed sensor shows substantial improvements in comparison to many previously reported electrodes for nitrite ion. The electrode was successfully applied also to the monitoring of nitrite ion in drinking water, soil and for determination of nitrogen dioxide in the air.