Probing the retention mechanism of small hydrophilic molecules in hydrophilic interaction chromatography using saturation transfer difference nuclear magnetic resonance spectroscopy.
Journaljournal of chromatography a4.049Date
2020 Apr 29
3 months ago
Publication Type
Journal Article
2020-Jul-19 / 1623 : 461130
Shamshir A 1, Dinh NP 2, Jonsson T 2, Sparrman T 3, Irgum K 4
  • 2. Diduco AB, Tvistevägen 48C, S-90736 Umeå, Sweden.
  • 3. Department of Chemistry, Umeå University, S-901 87 Umeå, Sweden.
  • 4. Department of Chemistry, Umeå University, S-901 87 Umeå, Sweden. Electronic address: [email protected]
Benzoic Acid
Hydrogen-Ion Concentration
Hydrophobic and Hydrophilic Interactions
Magnetic Resonance Spectroscopy
Quaternary Ammonium Compounds
Static Electricity
The interactions and dynamic behavior of a select set of polar probe solutes have been investigated on three hydrophilic and polar commercial stationary phases using saturation transfer difference 1H nuclear magnetic resonance (STD-NMR) spectroscopy under magic angle spinning conditions. The stationary phases were equilibrated with a select set of polar solutes expected to show different interaction patterns in mixtures of deuterated acetonitrile and deuterium oxide, with ammonium acetate added to a total concentration that mimics typical eluent conditions for hydrophilic interaction chromatography (HILIC). The methylene groups of the stationary phases were selectively irradiated to saturate the ligand protons, at frequencies that minimized the overlaps with reporting protons in the test probes. During and after this radiation, the saturation rapidly spreads to all protons in the stationary phase by spin diffusion, and from those to probe protons in contact with the stationary phase. Probe protons that have been in close contact with the stationary phase and subsequently been released to the solution phase will have been more saturated due to a more efficient transfer of spin polarization by the nuclear Overhauser effect. They will therefore show a higher signal after processing of the data. Saturation transfers to protons in neutral and charged solutes could in some instances show clear orientation patterns of these solutes towards the stationary phases. The saturation profile of formamide and its N-methylated counterparts showed patterns that could be interpreted as oriented hydrogen bond interaction. From these studies, it is evident that the functional groups on the phase surface have a strong contribution to the selectivity in HILIC, and that the retention mechanism has a significant contribution from oriented interactions.
J Chromatogr Ajournal of chromatography a

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