PHASE DISCRIMINATION IN CONTINUOUS LIQUID-LIQUID-EXTRACTION WITH DIODE-ARRAY PHOTOMETRIC DETECTION

A high-resolution phase-discrimination approach for use in continuous liquid-liquid extraction monitoring is reported that uses any available diode array spectrophotometer to monitor the segmented flow at three wavelengths: one for discriminating the phases involved, another for monitoring the target species, and the third for correction of signal fluctuations. Two sizes of organic-aqueous-phase segmentation are produced along the dynamic system: short segment lengths favoring mass transfer between the immiscible phases and longer segments formed at the expense of the shorter ones in a grouping chamber in order to allow one of the phases to fully occupy the flow cell path length line during monitoring. The proposed approach was successfully used for continuous monitoring of both aqueous and the organic phases, as well as continuous liquid-liquid extraction processes involving chemical derivatization reactions.