A Dual Membrane Electrodialytic Phosphoric Acid Eluent Generator for Ion Exclusion Chromatography-A Gas-Free Electrodialytic Phosphoric Acid Generator

Relative to suppressed conductometric anion exchange chromatography, conductometric ion exclusion chromatography (IEC) is much less popular. Poor limit of detection and manual preparation of eluent are primarily responsible for this. We describe an electrodialytic phosphoric eluent generator for the online production of phosphoric acid eluent at a concentration exceeding 35 mM. It is a sandwiched configuration consisting of three channels isolated by stacked anion exchange membranes and a bipolar membrane plus stacked anion exchange membrane. Such a unique configuration ensures the production of gas-free eluent, obviating the need for a gas removal device. The resulting eluent concentration is controlled by varying the current. Coupled with an ultraviolet absorbance detector, a 0.04-16.67 mg/L limit of detection for model organic acids was achieved by IEC equipped with an electrodialytic phosphoric eluent generator.