Catalytic spectrophotometric determination of cerium by ion exchange separation coupled to a flow injection system

A flow injection method intended for the determination of cerium based on i ts catalytic effect on the oxidation of gallocyanine by peroxydisulfate in acidic media is described. The proposed flow injection manifold incorporate s a ion exchange separation system in the carrier stream. The decolorizatio n of gallocyanine due to its oxidation was used to monitor the reaction by spectrophotometry at 524 nm, The variables which affected the reaction rate were fully investigated. By this method, Ce(IV) can be determined in the r ange 0.30-10.0 mu g, with a limit of detection of 0.25 mu g. The relative s tandard deviation for ten replicate determinations of 1.0 mu g of Ce(IV) wa s 1.8%. The method was used for the determination of cerium a in real sampl e.