Flow injection determination of nitrite by amperometric detection at a modified electrode

The modification of a glassy carbon electrode by coating it with poly(4-vinylpyridine), which is subsequently impregnated with IrCl64–,3–, yields an indicator electrode that permits the detection of 0.07 p.p.m. (mg l–1) of nitrite in 20 µl of solution in a flow injection experiment. The slope of the calibration graph in the range 1 × 10–5-1 × 10–3M nitrite is only half of that obtained for a bare glassy carbon electrode, but the anion-exchange polymer coating attenuates the interference of cations such as PbII, MnII and FeII. The coating also prevents the surface poisoning effect of thiocyanate, which has previously limited the use of bare glassy carbon and platinum electrodes for this determination.