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E-Journal of Chemistry
Volume 3 (2006), Issue 3, Pages 146-153

Rapid Spectrophotometric Determination of Trace Amounts of Nitrate-Nitrogen Using Dapsone and α-Naphthol

Padmarajaiah Nagaraja, Jainara S. Prakash, and Besagarahally L. Bhaskara

Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore-570 006, India

Received 10 May 2006; Accepted 2 June 2006

Copyright © 2006 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A simple, rapid and sensitive spectrophotometric method has been developed for the trace determination of nitrite using Dapsone and α-Naphthol. The proposed method is based on the diazotization of Dapsone followed by coupling with α-Naphthol in sodium hydroxide medium to give an intense pink coloured azo dye. The dye shows absorption maximum at 540 nm. The molar absorptivity and Sandell’s sensitivity being 5.749 × 104 l mol-1 cm-1 and 0.24 ng cm-3 respectively. Tolerance limit for interfering ions and complexing agents were reported. Other analytical parameters and applications of the method for analysis of tap water, lake water, and industrial effluents have been investigated.