Spectrophotometric determination of moclobemide by charge-transfer complexation

A simple and sensitive spectrophotometric method is described for the assay of moclobemide. The method is based on the molecular interaction between the drug and chloranilic acid, to form a charge-transfer complex in which the drug acts as n-donor and chloranilic acid as π-acceptor. Chloranilic acid was found to form a charge-transfer complex in a 1:1 stoichiometry with a maximum absorption band at 526 nm. Conformity with Beer's law was evident over the concentration range 4–36 mg 100 ml −1. A complete, detailed investigation of the complex formed was made with respect to its composition, association constant, molar absorptivity and free energy change. The method has been applied successfully to the analysis of commercially available moclobemide tablets with good recovery and reproducibility.