STOPPED-FLOW KINETIC DETERMINATION OF A BINARY MIXTURE - SIMULTANEOUSDETERMINATION OF EUROPIUM AND CERIUM

A kinetic method is proposed for the simultaneous determination of eur opium(II) and cerium(III), based on their inductive action on the Cr(V I)-iodide redox reaction in weak acidic medium. The reaction rate was followed by the stopped-flow spectrophotometric technique using starch -iodine complex as indicator. The method can be used for the determina tion of europium and cerium after reduction with zinc metal powder in the concentration ranges 0-2.1 and 0-1.8 mug/ml, respectively. The det ection limits are 0.015 mug/ml Eu and 0.010 mug/ml Ce. 100 to 1000 tim es higher concentrations of other rare earth metal ions and Th4+, Al3, Mn2+, Hg2+, Co2+, Ni2+, Cu2+, Pb2+ do not interfere. The method is a pplied to the determination of europium and cerium in a synthetic samp le and in barium yttrium fluoride fluorescent material, with relative standard deviation of about 4%.