Studies on the Charge-Transfer Interaction Between Tamoxifen Citrate and Chloranilic Acid

The complex formed as a consequence of the interaction between the electronacceptor P-chloranilic acid and an electron donor tamoxifen citrate was employed in the assay of the drug in pure powder and tablets. Chloranilic acid was found to form a charge-transfer complex in a 1:1 stoichiometric ratio, with tamoxifen citrate. The wavelength of maximum absorption for the complex was found to be 550 nm while the absorbance was linear over the concentration range of 2-100 g/ml. Evaluations of the various thermodynamic parameters by means of the Scott equation was carried out and were found to decrease with increase in temperature. The free energy change (G°) and the enthalpy of formation (H°) as well as the entropy (S°) were determined for various interactions. Results obtained suggest that the proposed method may be conveniently applied in the analysis of commercially available tamoxifen citrate tablets with a high degree of accuracy and reproducibility.