DIRECT DETECTION OF TRACE LEVELS OF URANIUM BY LASER-INDUCED KINETIC PHOSPHORIMETRY

The kinetic phosphorimetric determination of uranyl ion in aqueous solutions at room temperature yielded a detection limit for UO22+ of 1 ng/L. The response to uranium is linear from the detection limit up to 5 mg/L. The method is fast and accurate, with no separative pretreatment needed for most of the real samples investigated. In the analysis of biological samples, wet-ashing with HNO3/H2O2 is required for measurements near the detection limit. Samples with uranium concentrations higher than 0.1-mu-g/L gave relative standard deviations typically below 5%. Factors affecting the quantum yield of the uranyl ion phosphorescence, e.g. quenching from species present in the matrix, are accounted for in the kinetic analysis of the uranyl phosphorescence.