KINETIC-CATALYTIC DETERMINATION OF OSMIUM BY FLUORESCENCE QUENCHING WITH SALICYLFLUORONE AND HYDROGEN-PEROXIDE

A highly sensitive and selective fluorescence-quenching kinetic method is proposed for the determination of trace osmium(IV), based on the catalytic effect of osmium(IV) on the salicylfluorone (lambda(ex) = 510 nm, lambda(em) = 535 nm)-H2O2 system at pH 9.3-9.6. Using the fixed time method, osmium(IV) in the range 0.008-0.6 ng/ml can be determined. The detection limit is 0.006 ng/ml. Over thirty anions and cations, including other platinum metal ions, do not interfere, even when present in large excess. The method has been applied successfully for the determination of osmium in a series of synthetic mixtures and refined ore with relative standard deviations of 2-6%.