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ISRN Spectroscopy
Volume 2012 (2012), Article ID 869493, 5 pages
Research Article

Novel Reagents for the Spectrophotometric Determination of Isoniazid

Department of Chemistry, Mangalore University, Karnataka, Mangalagangothri 574 199, India

Received 11 April 2012; Accepted 10 May 2012

Academic Editors: A. A. Ensafi, D. V. Konarev, and N. Zanatta

Copyright © 2012 Divya N. Shetty et al. 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.


Isoniazid is an antitubercular drug, widely used for tuberculosis. Owing to its importance in therapeutics, the present study aims to develop simple method for the spectrophotometric determination of isoniazid (INH). Two novel reagents, epichlorohydrine (ECH) and 4-hydroxyphenaylchloride (HPC) are used for the spectrophotometric determination of INH. Based on the nucleophilic substitution reactions of INH with EPI & HPC in basic medium, rapid, simple, inexpensive, precise, and accurate visible spectrophotometric method is proposed for the determination of INH in bulk drug and in formulations. Method involves the reaction of INH with EPI and HPC in basic medium to form yellow-colored chromogen, measuring the absorbances at 405 and 402 nm for INH-EPI & INH-HPC, respectively. The optimum experimental conditions have been studied. The absorbance was found to increase linearly with the concentration of the drug and formed the basis for quantification. The calibration graphs were linear from 2.00–22.00 μg mL−1 and 20.00–120.00 μg mL−1 for INH-EPI & INH-HPC, respectively. The apparent molar absorptivity and Sandell's sensitivity are calculated to be 0 . 5 1 × 1 0 4 & 0 . 1 0 × 1 0 4  L mol−1 cm−1 and 0.027 & 0.134 μg cm−2 for INH-EPI & INH-HPC, respectively. The procedure is used to determine INH in pharmaceutical products. The associated pharmaceutical materials do not interfere in the measurements.