Voltammetric determination of organic nitrogen compounds in environmental samples using carbon paste electrode modified with activated carbon

A quick and simple procedure is described to determine pyridine and quinoline using voltammetric methods and carbon paste electrodes modified with activated carbon in the proportion of 50:20:30 w/w graphite:activated carbon:silicon. Studies with cyclic voltammetry indicated that reduction of organic nitrogen molecules is irreversible in ammonium chloride solution acidified to pH 2.5 with Britton-Robinson buffer. Under the best optimum conditions for the differential pulse voltammetry for pyridine and square wave voltammetry for quinoline, the analytical curve was linear from 1.0 x 10(-4) to 9.0 x 10(-7) mol L-1 for both analytes with limits of detection of approximately 2.0 x 10(-7) mol L-1 and limits of quantification of approximately 7.0 x 10(-7) mol L-1. The proposed methods were successfully applied to determine pyridine and quinoline in samples of textile effluents and fuel with minimum sample treatment.