Uranium(VI) On-Chip Microliter Concentration Measurements in a Highly Extended UV-Visible Absorbance Linearity Range.

The reduction of effluents deriving from analytical control is a serious concern in the nuclear industry, for both production and R&D units. In this work we report an alternative methodology for the standard UV-vis absorbance analyses for actinides concentration monitoring along the plutonium uranium refining extraction (PUREX) process. This methodology, based on photonic lab-on-a-chip (PhLoC) technology, enables drastic sampling reduction down to a few microliters and simultaneously allows to track concentrations over several orders of magnitude while maintaining a detection linearity range. A PhLoC microfluidic platform was specifically designed to allow online sample injection with zero dead volume connectivity and the on-chip spectrophotometric approach, based on a multiple optical path configuration, was tested for the determination of uranium(VI) concentrations from 0.1 to 200 g L, showing that linearity is maintained within high levels of confidence. These results provide the proof of concept for the transposition of current analytical methods for actinides, including plutonium, to microfluidic systems.