ABSTRACT
Acknowledgments .................................................................................................. 154 References .............................................................................................................. 154
Reversed-phase liquid chromatography (RPLC) has been the method of choice for the analysis of various classes of compounds not amenable to gas chromatography (GC). A large number of compounds were preferably measured by RPLC and C18based silica stationary phases. Yet, highly polar compounds undergo early elution on traditional RP stationary phases, leading to lower sensitivity of the mass spectrometric (MS) detection due to high water percentage in the mobile phase at the beginning of the run. The analysis of highly hydrophilic, ionic, and polar compounds by hydrophilic interaction liquid chromatography (HILIC) coupled to MS has been demonstrated as a valuable complementary approach to RPLC.1 The use of a low aqueous and high polar organic mobile phase in HILIC separation is almost ideal for electrospray ionization in many cases, resulting in increased sensitivity.1
