Improvements in ion reflux: An electrodialytic eluent generation and suppression device for ion chromatography

• Integrated membrane-based electrodialytic eluent generation and suppression device.
• Water is pumped phase, with virtually zero waste generated.
• Isocratic and gradient chromatography performance shown to be equivalent.
• Stable faradaic behavior.

This work describes a membrane based electrodialytic ion reflux device (IRD), which uses water as the pumped phase and integrates isocratic and gradient eluent generation and suppression. The current design incorporates several ion exchange membranes to create discrete chambers for suppression and eluent generation, while isolating the electrodes from the analytical stream. A small volume of recycled water can be used as the pumped phase while continuously refluxing the eluent ions. This current design permits electronically controlled eluent generation of at least 16.4 μeq KOH min−1, while maintaining low suppressed background conductivity (<0.5 μS/cm). The device was operated in gradient or isocratic mode continuously for up to 6 weeks. During this period, over 500 gradient and isocratic injections were performed, showing peak retention time precision below 1.5% RSD.