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International Journal of Analytical Chemistry
Volume 2009, Article ID 307045, 11 pages
Research Article

New Sensitive Kinetic Spectrophotometric Methods for Determination of Omeprazole in Dosage Forms

Department of Pharmaceutical Analytical Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71256, Egypt

Received 13 January 2009; Revised 30 July 2009; Accepted 8 September 2009

Academic Editor: Pavel Jandera

Copyright © 2009 Ashraf M. Mahmoud. 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.


New rapid, sensitive, and accurate kinetic spectrophotometric methods were developed, for the first time, to determine omeprazole (OMZ) in its dosage forms. The methods were based on the formation of charge-transfer complexes with both iodine and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The variables that affected the reactions were carefully studied and optimized. The formed complexes and the site of interaction were examined by UV/VIS, IR, and 1H-NMR techniques, and computational molecular modeling. Under optimum conditions, the stoichiometry of the reactions between OMZ and the acceptors was found to be 1 : 1. The order of the reactions and the specific rate constants were determined. The thermodynamics of the complexes were computed and the mechanism of the reactions was postulated. The initial rate and fixed time methods were utilized for the determination of OMZ concentrations. The linear ranges for the proposed methods were 0.10–3.00 and 0.50–25.00  𝜇 g m L − 1 with the lowest LOD of 0.03 and 0.14  𝜇 g m L − 1 for iodine and DDQ, respectively. Analytical performance of the methods was statistically validated; RSD was <1.25% for the precision and <1.95% for the accuracy. The proposed methods were successfully applied to the analysis of OMZ in its dosage forms; the recovery was 98.91–100.32%  ± 0.94–1.84, and was found to be comparable with that of reference method.