A Highly Current-Efficient Electrodialytic Membrane Suppressor for Ion Chromatography

We describe a highly current-efficient electrodialytic membrane suppressor (EMS) for ion chromatography. The device features a typical sandwich-like configuration, where a central eluent channel is spatially isolated from two outer regenerant chambers by two cation exchange membranes (CEMs). The CEM is in intimate contact with sulfonated functionalized screens in the eluent and regenerant chambers, with the aim to reduce the resistance. By using a lightly sulfonated screen with suitable low capacity (e.g., in the range of 40-80 μeq/g) in the eluent channel, the EMSs obtained show 100% current efficiency toward common hydroxide eluent. For example, the suppression current at 16.1 mA or 32.2 mA (theoretical current) allows effective suppression to 10 mM or 20 mM KOH eluent at the typical flow rate of 1 mL/min, as indicated by <1 μS/cm of the suppressed background. The suppressor is able to accommodate suppression of hydroxide eluent up to 80 mM KOH.