Spectrophotometric determination of some pharmaceutically-important aminoquinoline antimalarials

A simple and rapid spectrophotometric method for the assay of amodiaquine hydrochloride, chloroquine phosphate and primequine phosphate is described. The method is based on the interaction of the drug with tetracyanoethylene to give a stable charge transfer complex. The spectra of the complex show maxima at 413, 415 and 415nm, respectively, with high apparent molar absorptivities. Beer's law is obeyed in the concentration ranges 2–12, 1–8 and 2–12 g ml^–1 of the three drugs studied. The proposed method is applied to the determination of these drugs in certain formulations and the results are favourably comparable to the official methods.