Miniaturized crossflow ion transfer device for post-column enrichment in ion chromatography

The sensitivity of an ion chromatography system was improved using electrodialytic post-column enrichment. Even though post-column reactions, such as suppression, have been used to enhance the sensitivity, there are only a few methods available to increase the concentration and improve the sensitivity. Post-column in-line enrichment was achieved with a miniaturized crossflow ion transfer device (ITD) prepared in our laboratory. In the crossflow ITD, separated ionic solutes in the suppressed eluent were transferred into the acceptor solution (in-line purified ultrapure water), which had a flow rate less than that of the eluent. Because of highly efficient ion transfer, the analytes were enriched in the acceptor solution and the enrichment factor was depending on flow rate ratio of acceptor to eluent. Furthermore, the crossflow ITD minimized peak dispersion in the channel. The limit of detection improved by 5.0 ± 0.3 times when the flow rate ratio was 10.