SHARC™ HPLC columns are the latest innovation from SIELC Technologies, the inventors of Primesep®. SHARC columns are the first commercially available columns with separation based primarily on hydrogen bonding. SHARC stands for Specific Hydrogen-bond Adsorption Resolution Chromatography.
Hydrogen bonding is an interaction between hydrogen atom bound to electronegative atoms in a molecule, such as oxygen, nitrogen, fluorine. This is typically a weak interaction, especially when separation is performed in aqueous solutions. Liquid chromatography techniques evolved as tool for separation of different molecules based on their physico-chemical properties. Most common techniques of the separation are:
- Hydrophobic separation based on degree of hydrophobicity of the molecule
- Ion-exchange separation based on number, nature, and distribution of charges in the molecule.
- Normal phase separation based on hydrophilic properties of the molecules including molecule dipoles value and dipoles position
- Size exclusion separation (SEC) based on molecule size and shape.
Columns and stationary phases based on these techniques never perform purely with one type of interaction. Hydrogen bonding is omnipresent in every one of these techniques with minor contribution to retention and selectivity. However, in some cases, especially in normal phase chromatography, the contribution of hydrogen bonding can be significant. SHARC 1 is the first column specifically design to perform a separation based entirely on the interaction of the molecules capable providing hydrogen atom (donor) or attract hydrogen atom (acceptor) to the stationary phase with special properties.
SHARC 1 column operation conditions are unique. A mixture of acetonitrile (MeCN), a weak solvent, and methanol (MeOH), a strong solvent, are used as the mobile phase. Pure MeCN has very insignificant amount of hydrogen bonding with the SHARC stationary phase, while MeOH interacts strongly with SHARC stationary phase, which reduces the retention of analytes based on it’s capacity to hydrogen bond. By changing ratio of MeCN/MeOH the optimum retention profile can be obtained for many types of molecules with high selectivity, peak shape, efficiency, and speed.
Hydrogen bonding energy is usually in range of 30 kJ/mol or less and depends strongly on the nature of the functional groups and their orientation within the molecule. This energy difference is the basis for selectivity of the interaction between the stationary phase and the molecule of different structure and chemical characteristics.
A given molecule can retain on the stationary phase with more than one hydrogen bond, while also performing as a donor or acceptor of a hydrogen atom.
Presence of a polarized hydrogen atom is not always enough to observe retention by hydrogen bond mechanism. Sometimes a compound can form intramolecular interactions, as oppose to intermolecular hydrogen bonding, and does not participate in stationary phase interaction.
SHARC 1 column is a hydrogen acceptor type stationary phase showing higher retention characteristics toward molecules with higher number of polar X-H bonds such as alcohols, amines, acids, amides, phenols etc.