Table of Contents Author Guidelines Submit a Manuscript
International Journal of Analytical Chemistry
Volume 2015 (2015), Article ID 241412, 7 pages
Research Article

Pregabalin and Tranexamic Acid Evaluation by Two Simple and Sensitive Spectrophotometric Methods

1Department of Chemistry, Faculty of Science, University of Karachi, Karachi 75270, Pakistan
2PCSIR Laboratories Complex Karachi, Shahrah-e-Dr. Salimuzzaman Siddiqui, Karachi 75280, Pakistan
3Faculty of Pharmacy, Federal Urdu University of Arts, Science and Technology, Karachi 75300, Pakistan
4Faculty of Medicine, Ziauddin University, Karachi 75600, Pakistan

Received 8 September 2014; Accepted 6 December 2014

Academic Editor: Mohamed Abdel-Rehim

Copyright © 2015 Nawab Sher 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.


This paper demonstrates colorimetric visible spectrophotometric quantification methods for amino acid, namely, tranexamic acid and pregabalin. Both drugs contain the amino group, and when they are reacted with 2,4-dinitrophenol and 2,4,6-trinitrophenol, they give rise to yellow colored complexes showing absorption maximum at 418 nm and 425 nm, respectively, based on the Lewis acid base reaction. Detailed optimization process and stoichiometric studies were conducted along with investigation of thermodynamic features, that is, association constant and standard free energy changes. The method was linear over the concentration range of 0.02–200 µgmL−1 with correlation coefficient of more than 0.9990 in all of the cases. Limit of detection was in range from 0.0041 to 0.0094 µgmL−1 and limit of quantification was in the range from 0.0137 to 0.0302 µgmL−1. Excellent recovery in Placebo spiked samples indicated that there is no interference from common excipients. The analytical methods under proposal were successfully applied to determine tranexamic acid and pregabalin in commercial products. -test and ratio were evaluated without noticeable difference between the proposed and reference methods.