Hydrophilic interaction liquid chromatography (HILIC) is becoming an increasingly popular technique that offers complementary selectivity to reversed-phase. With the ability to retain highly polar and hydrophilic compounds, this new HILIC range of columns has been developed to aid the analysis of compounds that are traditionally difficult to retain using conventional C18 columns. Available with 1.9, 3 and 5 µm particle sizes, Hypersil GOLD HILIC columns are ideal for applications within drug discovery, food testing and environmental analysis. HILIC works by incorporating water in the highly organic mobile phase to form, an adsorbed water-rich layer on the polar stationary phase surface into which analyte molecules partition. Retention is governed by dipole-dipole interactions and hydrogen bonding mechanisms. Furthermore, the highly organic mobile phase contains low salt levels, making Hypersil GOLD HILIC columns ideal for use with electrospray mass spectroscopy.