Miniaturized Low-Pressure Ion-Exchange Module and Its Application to an Acidic Eluent Generator for Open Tubular Ion Chromatography

We describe a miniaturized eluent generator (MEG), which can be integrated into open tubular capillary column ion chromatography (OTCC-IC). The MEG consists of one central eluent channel and two feed acid chambers, with each phase isolated by a cation-exchange membrane (CEM) and an anion-exchange membrane (AEM). Pure water flowed through the central eluent channel while acid solution (HA) was fed to both chambers. Applying the electric field to the MEG, H+ and A- simultaneously and respectively through the CEM and AEM to form HA in the central channel. The MEG successfully produced tartaric acid and 2,6-pyridinedicarboxylic acid as the eluent for cation OTCC-IC. The gradient elution improved the peak resolution and analytical window for five common cations (Na+, NH4+, K+, Ca2+, Mg2+).