Ion Chromatograph: Eluant Preparation

Eluant is the mobile phase that transports the sample ions through the ion chromatograph plumbing, including the columns. The pH, ion concentration, and ion types in the eluant determine the partitioning of the analyzed ions between the stationary phase (ion exchange resin in the columns) and the eluant.

Both of our current instruments make their own eluant from deionized water, and eluant generator cartridges. The eluant is prepared by electrolysis in the eluant cartridge module. The anion system produces KOH eluant, typically 10 to 50 mM, and the cation system produces methylsulfonic acid (HSO4CH3), also typically 10 to 50 mM.

We therefore don’t have to make eluant for routine analyses. Occasionally we have to make special eluants for cleaning contaminated columns. Instructions are around for these. Basically, once the proper eluants are mixed they have to be put in the eluant bottle, and run as usual. At least I think that’s the case. Cleaning solutions may damage some of the parts before the column (eluant generator, degassing system, for example), and parts after the column (suppressor, for example). Check instructions.