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


Fang Tian and Sheng-Yun Li*   Pages 1 - 6 ( 6 )


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. 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 1.86×104 L mol-1cm-1 at 425 nm. The CT complexation was also confirmed by both FTIR and 1H NMR measurements. The thermodynamic properties and reaction mechanism of the CT complexation have been discussed. 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.


Charge transfer complexation, epsilon aminocaproic acid, spectrophotometry, p-nitrophenol, FTIR, NMR


Department of Chemistry, Taiyuan Normal University, Jinzhong, Department of Chemistry, Taiyuan Normal University, Jinzhong

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