Normal Phase Hydrophilic Interaction Chromatography
While reversed phase is the most widely used mode of retention in HPLC, very polar compounds are often not sufficiently retained in low percent organic, or even in 100% aqueous mobile phase. The order of elution in normal phase is opposite that found in RPC for the same mixture of compounds. Although non-polar organic mobile phases and a silica stationary phase were used traditionally in normal phase LC, today most normal phase separations are performed with aqueous-organic mobile phases and a more polar-bonded stationary phase. This mode of HPLC is now commonly referred to as HILIC, hydrophilic interaction chromatography.
By using an amide or amino bonded phase column, polar compounds can be retained by a normal phase or hydrophilic interaction chromatography (HILIC; see references) retention mechanism using a mobile phase mixture of acetonitrile and ammonium acetate buffer. In contrast to the retention behavior in reversed phase, in HILIC, solutes will be retained longer when increasing the percent acetonitrile.
|
TSKgel Amide-80 |
TSKgel NH2-100 |
Bonded Phase |
- Amide-80 bonded phase does
not react with reducing sugars.
- Anomer formation can be
prevented by raising mobile
phase temperature up to 80°C.
|
- NH2-100 bonded phase is more stable than conventional amino phases due to a special endcapping prior to introduction of aminoalkyl groups.
- Amino-bonded phase can react with a reducing sugar to form a Schiff base. |
Detectors |
Can be used with evaporative light scattering
(ELS) and mass spec (MS) detectors
|
Mobile Phase |
Stable in 100% organic eluents |
Solutes |
Retains very polar drug candidates and drug metabolites |
Applications |
- saccharides
- polyols (polyalchols)
- drug metabolites
- peptides
- melanine & cyanuric acid
- oligonucleotides
- polar compounds in
- fermentation broth
cystosine |
- saccharides
- polyols (polyalchols)
- methotrexate polyglutamate derivatives
- pyridylaminated oligosaccharides
- water-soluble vitamins
- nucleic acid fragments |