SINGLE-PHASE LIQUID-LIQUID-EXTRACTION IN MONOSEGMENTED CONTINUOUS-FLOW SYSTEMS

Monosegmented continuous-flow analysis (MCFA) was evaluated for the realization of automatic single-phase liquid-liquid extraction. The single-phase mixture is generated by confluence of three solutions (isobutyl methyl ketone-thenoyltrifluoroacetone (IBMK-TTA), aqueous sample solution and ethanol). The resulting homogeneous solution is passed through a sample loop of an MCFA manifold and introduced into a reaction coil. Rapid and almost complete reaction between the analyte and complexing agent is obtained in the single phase. Subsequently, the single-phase monosegment containing the analyte complexed by TTA is broken into two phases (organic and aqueous) by adding saturated NaNO3 solution. The organic portion containing the extracted analyte finally occupies the superior part of the monosegment and is passed through an on-line spectrophotometric detector. The system does not make use of a segmenter or separation device such as is usually employed in continuous-flow extraction methods. The sensitivity of the MCFA single-phase approach is closer to that of the conventional manual extraction method while samples can be processed at 60-80 h(-1).