Flow-injection analysis of cobalt(II) utilizing enhanced lophine chemiluminescence with hydroxylammonium chloride

A rapid and convenient flow-injection method is described for the determination of Co(II). The method utilized the phenomenon that the lophine-Co(II)-H2O2 chemiluminescence (CL) reaction is enhanced in alkaline media by the addition of hydroxylammonium chloride. The calibration curve was linear over the range 2 x 10(-7) to 2 x 10(-5) M with a detection limit of 4.5 x 10(-8) M (0.9 pmol) at a signal-to-noise ratio of 2. The method was applied to the assay of cyanocobalamin in commercially available eye lotions.