Autonomous, waste-free eluent generation and suppression in a single device: Electrodialytic eluent reflux for ion chromatography

Eluent reflux provides a new approach to suppress and reflux (recover) eluent without the continuous generation of chromatographic waste. The current work utilized a device containing ion exchange membranes at the electrodes, in order to prohibit electrolysis gases from entering the eluent stream. Two resin beds (separated by a membrane stack) were responsible for suppressing incoming eluent and regenerating the suppressed eluent to nearly its original concentration after detection. A greater than expected dilution in the eluent concentration was observed as a result of the minor leakage of potassium ions through the anion membrane stack into the electrode chamber. The incomplete recovery of the eluent was offset by the addition of a three port valve (DRV) to regulate eluent concentration. Over 48 h of continuous operation (192 injections), the deviceʹs performance was stable (RSD of 0.21% with the three port valve, compared to RSD 3.73% without). The device was able to operate for up to four weeks using 1 L of eluent. Chromatograms showing the reproducibility of the device are presented for anions.