A cation exchange resin bead-based microscale electrolytic suppressor for capillary ion chromatography

A cation exchange resin (CER) bead-based microscale electrolytic suppressor for capillary ion chromatography (CIC) has been fabricated and evaluated. Relative to common ion exchange membrane, the use of CER beads presents a simple way to fabricate a microscale suppressor due to its small surface area and spherical shape. The internal volume of the device is ∼600 nL, which matches the requirements by CIC. Continuous online regeneration is readily achieved using pure water or diluted sulfuric acid as the regenerant. The use of a cation exchange functionalized monolithic segment inserted between two CER beads greatly reduces the electrical resistance and improves the suppression efficiency. The device works well only in the electrolytic mode, chemical regeneration alone is ineffective. The suppressed background is ∼3 μS/cm for 10 mM KOH eluent generated online by a microscale KOH electrolytic generator operated at the flow rate of 3 μL/min. The preliminary application for capillary ion chromatography has been demonstrated.