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Differential-pulse adsorptive stripping voltammetric method for the determination of nitrite at p.p.b. levels after diazotisation of aniline and coupling with azulene and its modification for the determination of aromatic amines.

A differential-pulse adsorptive stripping voltammetric method for the determination of nitrite has been developed based on the diazotisation of aniline and coupling of the resulting diazonium salt with azulene in dilute perchloric acid solution. The reaction mixture is then adjusted to pH 9 in order to accumulate and determine the azo dye formed at a hanging mercury drop electrode. The determination is limited to about 4 × 10–9M nitrite owing to the rather high blank. The derivatisation time, however, is less than 30 min. Calibration graphs are rectilinear up to at least 8 × 10–8M(for a 2 min accumulation time) and the coefficients of variation (five determinations) are typically <2% at the 1 × 10–8M level. Aniline and other aromatic amines can be determined at a similar level by modification of this method.