Analytical potential of separations by liquid ion exchange

Abstract

While extractions by liquid anion exchange with alkylamines or quaternary ammoniums and by liquid cation exchange with (especially) organophosphorus acids are being developed intensively for chemical processing, they appear as yet to be used considerably less than other types of extractions in analytical chemistry. It is suggested that this results from chance and habit rather than from any lack of potential usefulness, and that liquid ion exchange warrants increased attention from analytical chemists. Some of the advantages that have proved important in chemical processing should apply also to analytical use. When extractions reported from process and physicochemical applications are included along with analytical reports, a considerable range of extractions is already available to suggest and guide further uses. A representative compilation of such extractions is summarised, and the controlling variables in some of the typical liquid ion-exchange systems are reviewed.