Liquid segmentors

Hitherto, most FI liquid-liquid extractions are performed in a multi-segmented flow comprised of the two immiscible phases. Since the extraction coil is merely an extension of the outlet of the segmentor, the two components may be viewed upon as a single pan in the FI manifold. This pan of the manifold is closely connected with the propulsion system which should meet the demands for the delivery of organic solvents. Although these may be satisfactorily propelled by solvent resistant piston pumps, peristaltic pumps are used more frequently, often making the displacement bottle (cf. Sec. 2.1.1) an indispensable component of this pan of the manifold. 

Fig3.13 Schematic diagram of a typical FI manifold for liquid-liquid extraction spectrophotometry. R pump DB. displacement bottle C. carrien R, reagent S. sample SG, phase segmentor EC. extraction coil SR phase separator R. restrictor or impedance coil D. detector W. waste. 

The post-column connection of an HPLC to FI liquid-liquid extraction appears to present no major difficulties, and effluent from the chromatograph column may be connected to the solvent segmentor of the extraction system or between this point and the extraction coil. 

Figure 5.7 A schematic diagram of the online coupling of liquid-liquid extraction with GC. O, 50 ml glass syringe with extraction solvent, flow rate 138 t,lmin S, 50 ml glass syringe with sample, flow rate 1430 xl min PI, phase segmentor E, polymer-coated glass extraction coil (5 m x 0.7 mm id) P2, phase separator with Teflon membrane, 0.2 xm pore size W, waste V, rotary valve with variable loop (load position) C, carrier gas inlet GC, gas chromatography [1 ].

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