Use of suppressors for signal enhancement of weakly-acidic analytes in ion chromatography with universal detection methods

Suppression has enabled ion chromatography (IC) to be established as the leading technique for analysis of strong acids and bases. However, the determination of weakly-ionized species (e.g., weak organic acids) by IC is challenging due to the low conductance of the analytes after ion suppression. Moreover, when weak acids or bases have low absorbance, other universal detection methods are required for successful analysis, but the use of non-volatile ionic eluents in IC frequently prevents this option being used.We review different approaches to the conductivity detection of weakly-ionized analytes, with emphasis on the role of suppressors for conductivity-signal enhancement through the use of post-column ion-exchange reactions. We provide typical signal-enhancement factors for each method.This review also focuses on the use of suppressors as eluent de-salting devices to enable coupling of IC to universal detectors (e.g., mass spectrometry), evaporative light-scattering detectors and charged-aerosol detectors.

► Signal enhancement for weak organic acids using suppressors in ion chromatography.
► Post-suppressor conductivity-signal enhancement using ion-replacement reactions.
► Suppressors used as desalting devices for MS, ELSD and CAD after gradient-elution IC.
► Suppressors considerably extend the scope of ion chromatography to weak organic acids.