Extractive Ion-Pair Spectrophotometric Assay of Amodiaquine

The quality of antimalaria drugs is a concern in malaria treatment and management. The quality of these drugs can be monitored and assured if simple, sensitive and accurate methods are available for routine use. Thus this extractive ion-pair spectrophotometric method was developed. Ion-pair was formed from equimolar concentration (10-4 M) of amodiaquine (5 ml) and bromocresol green (10 ml) in phthalate buffer (pH 5, 10 ml). The ion-pair was extracted into chloroform; re-extracted into 0.1 M sodium hydroxide; and determined spectrophotometrically. International Standard Requirements validation parameters were determined to evaluate the method applicability. The recovery data of the method was statistically compared with those obtained using nonaqueous titration. The extract absorbed maximally at 620 nm. The extract showed a stoichiometry of 1:2. Beer's law was obeyed in the concentration range of 1-50x 10-4 M of amodiaquine with good linearity (R> 0.99). A good accuracy was obtained from recovery studies. The extract was stable over 48 hours. The method complied with International Standard Requirements. The method compared positively with nonaqueous titration. Thus the method is good for amodiaquine analysis, with increased sensitivity from re-extraction into 0.1M sodium hydroxide. The method is simple; equipment and materials are readily available and no significant interference from common excipients.