The Metrosep C 4 - 250/4.0 is the cation column with the greatest capacity in the C 4 series. It is predestined for applications which require the highest separating efficiency. Samples with extreme differences in concentrations can be analyzed reliably with this column. The performance capability of the column is demonstrated, for example, when analyzing feed water for which the requirement is the perfect quantification of 7 µg/L sodium in addition to 7 mg/L monoethanolamine (MEA). With the C 4 - 250/4.0, not only amines and transition metals, but also alkaline and alkaline earth metals can be determined in a single run.