Study of spectrophotometric characteristics of the charge transfer complexation of epsilon aminocaproic acid with bromanil

Abstract

A spectrophotometric method has been studied for the determination of epsilon aminocaproic acid (EACA) through charge transfer (CT) complexation with bromanil (TBBQ). The CT reaction has been carried out at 70 °C of the water bath for 30 min in the borax buffer solution. The spectrum obtained for EACA/TBBQ system shows the maximum absorption band at wavelength of 352 nm. The CT complex is also confirmed by both FTIR and ¹H NMR measurements. The stoichiometry of the CT complex is found to be 1:1 ratio by Job and straight line methods between the donor and the acceptor. At the optimum reaction conditions, Beer’s law is obeyed in a concentration limit of 2～8 µg mL⁻¹. The relative standard deviation is less than 1.5%. The apparent molar absorptivity is determined to be 1.16×10⁴ L mol⁻¹ cm⁻¹ at 352 nm. 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 form with a good precision and accuracy compared to official method as revealed by t- and F-tests.