RSpak NN-614 is packed with poly(hydroxymethacrylate) bonded with trace amounts of sulfo groups, and the main separation mode is the reversed phase mode. However, due to the sulfo groups, ion interaction also works. Acidic substances are separated by ion exclusion mode and elute faster. Neutral substances are separated by reversed phase and alkaline substances are separated by a mixture of reversed phase (in the case of hydrophobic structure) and ion exchange mode. Therefore, the elution order is basically as follows: first the acidic, then the neutral and finally the alkaline substances. The column is suited to the analysis of mixture of acidic, neutral and alkaline substances.