Determination of trace cadmium in environmental water samples using ion-interaction reversed-phase liquid chromatography with fluorescence detection

An ion-interaction reversed-phase liquid chromatographic method has been developed for the determination of cadmium at low μg/l concentrations in environmental water samples. Cadmium and other matrix metals were separated through on-column complexation with 8-hydroxyquinoline sulphonate, using an octadecylsilica column and a mobile phase containing 15% acetonitrile, 10–13 mM tetrabutylammonium hydroxide, 5 mM 8-hydroxyquinoline 5-sulphonic acid and 10 mM acetic acid–acetate buffer (pH 4.8–5.4). Under the above conditions Cd(II) could be easily resolved from excess concentrations of matrix metals and could be detected at concentrations as low as 2 μg/l using fluorescence detection at 500 nm (based upon a 100-μl injection). The method showed a slightly curved detector response over the range of interest [up to 1 mg/l Cd(II)] and was successfully applied to the determination of trace Cd(II) in water samples containing large excesses of Mg(II) and Zn(II) and other matrix metals.