Hydrophilic interaction liquid chromatography (HILIC) is a mode of chromatography in which polar compounds, such as amino acids, metabolites, biogenic amines, phosphates and sugars, are retained and separated on a polar stationary phase in the presence of an aqueous mobile phase containing a high percent organic modifier. HILIC is also known as normal/phase (NP) liquid chromatography. Retention in HILIC is thought to be a combination of hydrophilic, ion-exchange and reversed-phase interactions. TSKgel HILIC columns include the popular TSKgel Amide-80 columns and the NH2-100 columns. The Amide-80 HR column has higher specifications for plate count (N = 18,000 vs. 8,000) compared to the traditional 25cm x 4.6mm Amide-80 column.