Hydrophilic and hydrophobic quaternary amines, along with sodium ion, were separated by mixed-mode chromatography on a Primesep 200 column. Mechanism of retention for sodium and tetramethylammonium ions is cation exchange, while the tetrabutylammonium ion is retained by combination of reversed-phase and cation-exchange mechanisms. All three compounds are not UV-active and monitoring is done by ELSD/CAD.
| Column | Primesep 200, 4.6×100 mm, 5 µm, 100 Å |
|---|---|
| Mobile Phase | MeCN/H2O |
| Buffer | AmAc pH4.0 |
| Flow Rate | 1.0 mL/min |
| Detection | ELSD |