Spectrophotometric Determination of Aniline by Azo-Dye Formation with 2, 6-Dihydroxybenzoic Acid-Application to waters

A simple and sensitive Spectrophotometric method for the determination of aniline in aqueous medium is described. The method is based on the formation of a yellow coloured azo product from the diazotisation of aniline followed by a coupling reaction with 2,6-dihydroxybenzoic acid in the presence of sodium carbonate. Absorbance of the resulting yellow azo dye is measured at 432 nrn and is stable for 1 hour at least. Beer's law is obeyed in the concentration range of 5-80|ig of aniline in a final volume of 25ml, with a molar absorptivity of 4.2xl04l.morl.cm"!, a relative error of +1.13 to+ 4.40 % and a relative standard deviation of 0.30 to 0.76%, depending on the concentration level. The method is successfully employed for the determination of aniline in river and waste waters.