Computer-controlled flow injection analysis system for on-line determination of distribution ratios

An automated flow injection analysis (FIA) system has been developed for the rapid acquisition of liquid/liquid, metal ion distribution ratios (D). The system features automatic switching between aqueous metal sample and wash solutions, on-line solvent extraction, phase separation, and the simultaneous detection of the separated phases by diode-array spectrophotometry. A comparative study of manual, single-stage liquid/liquid extractions with the flow injection system was completed by using a new extraction system UO22+/benzene/TOPO (trioctylphosphine oxide)/HBMPPT (4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione). The batch and FIA methods yielded results generally within 5% of each other. The major differences between the two systems are that the FIA system is at least twice as fast, is less labor intensive, is more reproducible, and yields better statistics (a result of the FIA's speed and automation features). Slope analysis of the plotted data from the uranyl extraction studies indicates that the extraction complex is UO2(BMPPT)2(TOPO)