VOLTAMMETRIC BEHAVIOR AND ION CHROMATOGRAPHIC DETECTION OF NITRITE AT A DISPERSED PLATINUM GLASSY CARBON ELECTRODE.

Cyclic voltammetry was used to investigate the electrochemical behavior of nitrite at a platinum-modified glassy carbon electrode (Pt-CME) in phosphate buffer (pH 4.5). Experiments in flow injection analysis and ion-chromatography (IC) were performed to characterize the electrode as an amperometric sensor for the determination of nitrite ions. The effects of several common interferences on the amperometric signal were estimated. The electrode stability, precision, limit of detection, and linear range were evaluated at a constant applied potential of 1.1 V. Calibration plots were linear from 0.03 mu M to 0.5 mM with a slope of about 21 mu A/mM and a correlation coefficient of 0.9987. The limit of detection (LOD) was 15 nM (0.7 ppb) in a 100 mu L injection. The electrode response was sufficiently stable: over 6 h of operating time a 2.8 % signal loss was observed. The determination of nitrite in milk and pear juices was achieved by IC and the relevant results were compared with those obtained with a standard spectrophotometric method