RARE-EARTH TRACE DETERMINATION BY SIMULTANEOUS LASER-INDUCED FLUORESCENCE AND THERMAL LENSING SPECTROSCOPY AFTER HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY SEPARATION

The understanding of the radionuclides behaviour in groundwater is of major interest for radioelement migration modelling near a nuclear waste repository. In the case of lanthanides and actinides in groundwater, speciation of a particular oxidation state and its detection at very low level are the principal conditions to understand these mechanisms. In this scope, an experimental apparatus is developed with a double simultaneous detection: the first one is based on the thermal lensing effect through the flowing cuvette after the chromatographic liquid column and assures a good sensitivity for non fluorescent oxidation state determination, the second one is based on laser induced fluorescence measured in the same cuvette at 90-degrees-C of the first axis which is known to be one of the most sensitive technique. In this paper we discuss the experimental set-up, results obtained for Nd and U after separation and future developments on radioactive elements.