SIMPLE DEVICES FOR THE MEASUREMENTS OF ABSORPTION-SPECTRA AT LIQUID-LIQUID INTERFACES

Chemical reactions at liquid-liquid interfaces are an attractive subject in analytical sciences, especially in studies of solvent extraction, liquid membrane separation, counter current chromatography and ionselective liquid membrane electrodes. The role of an interface in the solvent extraction of metal ions was demonstrated in our recent work where we employed a high-speed stirring method to gain advantages of an agitated system, a high specific interfacial area and promotion of mass transfer.1The principle of this method is as follows; when the specific interfacial area is large, interfacial adsorption of a solute can result in a significant decrease of the orgaic phase concentration. This concentration decrease can be measured spectro-photometrically after continuous phase separation by use of a Teflon phase separator.2This method was applied to measurements of extraction rates as well as to interfacial adsorption in various extraction systems. This is, however, an indirect method with respect to detection of interfacial adsorption. Consequently, a direct spectroscopic approach is desired to identify interfacially adsorbed species. © 1994, The Japan Society for Analytical Chemistry. All rights reserved.