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

Abstract

The modification of a glassy carbon electrode by coating it with poly(4-vinylpyridine), which is subsequently impregnated with IrCl₆^4–,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 Pb^II, Mn^II and Fe^II. 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.