Determination of Epsilon Aminocaproic Acid Based on Charge Transfer Complexation with p-Nitrophenlol by Spectrophotometry

Introduction: Spectrophotometry was investigated for the determination of epsilon aminocaproic acid (EACA) with p-nitrophenol (PNP). The method was based on Charge Transfer (CT) complexation of this drug as n-electron donor with π-acceptor PNP. Methods: The experiment indicated that CT complexation was carried out at room temperature for 10 minutes in dimethyl sulfoxide solvent. The spectrum obtained for EACA/PNP system showed the maximum absorption band at a wavelength of 425 nm. The stoichiometry of the CT complex was found to be a 1:1 ratio by Job’s method between the donor and the acceptor. Different variables affecting the complexation were carefully studied and optimized. At the optimum reaction conditions, Beer’s law was obeyed in a concentration limit of 1~6 μg mL^-1. The relative standard deviation was less than 2.9%. The apparent molar absorptivity was determined to be 1.86x104 L mol^-1cm^-1 at 425 nm. The CT complexation was also confirmed by both FTIR and 1H NMR measurements. Results: The thermodynamic properties and reaction mechanism of the CT complexation have been discussed. Conclusion: The developed method could be applied successfully for the determination of the studied compound in its pharmaceutical dosage forms with good precision and accuracy compared to the official method comprising t- and F-tests.