Colorimetric Determination of Aniline Derivatives in Natural Waters

Abstract A rapid, direct, and sensitive colorimetric method has been proposed for the determination of aniline derivatives in surface waters. The method is based on diazotization of the primary aromatic amine and coupling with resorcinol or 1-naphthol. Hydroxy-azo dyes obtained have considerably high absorptivities, rendering the method sensitive enough to determine anilines at 0.1 ppm. The effects of pH, saline constituents of waters, coupling phenols, and substituents on color intensity are discussed. Coefficients of variation ranged between 6 and 0.5, according to the nature of aniline derivative and the amount determined. Precision of the method is greatly increased when the amount of the existent aniline ranges between 40 and 100 μg.