SPECTROPHOTOMETRIC DETERMINATION OF SOME AROMATIC DIAMINES USING SODIUM SULPHIDE AND AN OXIDANT

Document Type : Original Article

Authors

1 Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut, Egypt

2 Department of Chemistry, Faculty of Science, King Saud University, Riyadh Saudia Arabia

Abstract

A simple and selective colorimetric method was developed for quantitative determination of aromatic diamines; p-phenylenediamine, N,N-dimethyl p-phenylenediamine and N,N-diethyl-p-phenylenediamine. The method is based on the reaction of sodium sulphide with an aqueous solution of the diamine in presence of an oxidant at ambient temperature to form a methylene blue or ethylene blue like dyes. Absorption maxima of 597, 665 and 670 nm were obtained for the three compounds; respectively. Different oxidizing agents were tried e.g. Ce(IV), Fe(III) and N-bromo-succinimide (NBS). The color was developed within 5 minutes and remained stable for at least 24 hours. Linear calibration graphs with very small intercepts were obtained. The proposed method was applied successfully for determination of aromatic diamines in spiked water samples and in presence of other aromatic amines and excellent recoveries were obtained. Reaction products have been isolated and identified using microanalysis, UV and IR spectrometric methods.

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