Ion exchange membranes in ion chromatography and related applications

This review is a broad survey of ion exchange membranes (IEMs) in chosen areas of analytical chemistry. The coverage is comprehensive in ion chromatography (IC) applications, this includes in-line water purification for IC use, chemical and electrodialytic eluent suppression, eluent generation, eluent purification, pH modification, buffer generation, use in ion exclusion chromatography, charge-based detection, as well as suppressor-detector combinations. The use of IEMs in sample treatment using ion transfer devices and Donnan dialysis preconcentration are discussed. Introduction of reagents through an IEM, whether through a concentration gradient large enough to overcome the Donnan barrier or active electrodialysis, does not involve volumetric dilution. Reagent introduction in this fashion, enabling conductometric detection of otherwise non-ionized weak electrolytes, is discussed. Several important applications of IEMs, in which ion exchange plays little or no role, are discussed; these include (a) diffusion-based gas collection and analysis, (b) evaporative concentration in a flow system, (c) drying of gas streams and (d) sensing of moisture in gases and liquids. An important area that is not covered is ion-sensing with IEMs and/or ionophores.