FIA-spectrophotometric determination of 8-hydroxyquinoline with p-aminophenol

Abstract.

 A flow injection spectrophotometric method has been developed for the determination of 8-hydroxyquinoline (oxine). The procedure is based on the reaction between oxine and p-aminophenol (PAP) in 4 mol/l NaOH in the presence of 0.004 mol/l KIO₄. Using 500 μl injection volume, a PAP concentration of 100 μg/ml and 3.2 ml/min carrier flow, in each one of the three lines of a flow injection manifold, the method provides a sensitivity of 0.0353 absorbance units ml/μg of oxine and a limit of detection of 7.6 ng/ml, being the relative standard deviation (0.06%) of four replicate measurements of a solution containing 4 μg/ml of oxine. The effects of chemical and flow parameters have been carefully considered and the method has been applied to the determination of oxine in water samples at different pH values.