ABSTRACT
Hydrophilic interaction liquid chromatography (HILIC) was “rst introduced in the 1970s1 for carbohydrates analysis and subsequently de“ned by Alpert in 19902 as a variant of normal-phase liquid chromatography (NPLC). However, HILIC offers a series of advantages compared to NPLC. In the latter, stationary phase is polar and the mobile phase consists of apolar solvents, resulting in increased retention with increased polarity of the analyzed samples and/or stationary phase and/or decreased polarity of the mobile phase.3,4
Nevertheless, the nonpolar solvents used as mobile phases are often dangerous for environment, expensive, and quite toxic and not completely suitable to solubilize polar and hydrophilic compounds. In HILIC, a hydrophilic stationary phase
20.1 Introduction ..................................................................................................469 20.2 Protein Modi“cations: Glycosylation ........................................................... 471 20.3 Troubles in Glycoproteome Analysis ............................................................ 472 20.4 Enrichment Methods for Glycoproteome ..................................................... 473 20.5 HILIC: Mechanism and Material ................................................................. 474 20.6 HILIC: From Glycomics to Glycoproteomics .............................................. 477 20.7 Glycoproteomics by HILIC and Mass Spectrometry ................................... 478 20.8 Application to Biomarker Discovery ............................................................ 482 References ..............................................................................................................485
and a partly aqueous organic solvent mobile phase are used. Similarly to NPLC, the retention increases with increased polarity of the analyzed compounds and/or stationary phase and/or decreased polarity of the mobile phase. However, contrary to NPLC, HILIC uses aqueous-organic solvents with a high organic-solvent fraction as mobile phase, which demonstrate an increased solubility for the polar and hydrophilic compounds. For this reason, HILIC applications have seen a considerable increase of interest5-10 for the analysis of many categories of polar compounds, charged as well as uncharged, in complex sample mixtures.11
