As RSpak NN-814 is packed with polyhydroxymethacrylate bonded with trace amounts of sulfo groups, the main separation mode is the reversed phase mode. However, due to the sulfo groups, ion interaction also works. Acidic amino acids, such as aspartic acid, are separated by ion exclusion mode and elute faster. Neutral substances are separated by reversed phase and alkaline amino acids are separated by a mixture of reversed phase (in case of hydrophobic structure) and ion exchange mode. Therefore, amino acids basically elute in the following order: first the acidic amino acids, second the neutral amino acids and finally the alkaline amino acids .


Sample : 0.1 % each, 20 μL
1. Aspartic acid
2. Glycine
3. Alanine
4. Valine
5. Methionine
6. Isoleucine

Column       : Shodex RSpak NN-814 (8.0 mm I.D. x 250 mm)
Eluent       : 40 mM H3PO4 aq.
Flow rate    : 1.0 mL/min
Detector     : RI
Column temp. : 40 °C