Determination of certain aminoquinoline antimalarials through ternary complex formation

Abstract

Antimalarials consisting of quinoline derivatives, namely amodiaquine, chloroquine and primaquine, react with cobalt and thiocyanate ions to give stable ternary complexes. These complexes are readily extractable in nitrobenzene to give a greenish blue colour with maximum absorption at 625 nm that can be used for quantitative spectrophotometric analysis. The mean recoveries for authentic samples of amodiaquine hydrochloride, chloroquine phosphate and primaquine phosphate were 100.81 ± 1.77, 99.56 ± 1.37 and 99.95 ± 1.08%, respectively (p= 0.05). Alternatively, determination of the cobalt content of the nitrobenzene extract via atomic-absorption spectroscopy provides an indirect method for the determination of these antimalarials. The mean recoveries were 99.99 ± 2.16, 100.06 ± 2.6 and 100.0 ± 2.0%, respectively. Both methods were applied to the analysis of pharmaceutical preparations and the results obtained agreed well with those obtained by official methods.