Hydrophilic interaction liquid chromatography (HILIC) continues to be an important technique for the analysis of polar analytes. Although acetonitrile is commonly the organic solvent of choice in HILIC, many publications and applications incorporate methanol as either the primary organic solvent or as a smaller fraction of the overall mobile phase. Surprisingly, little is found in the literature regarding how methanol impacts the retention and selectivity.
In this work, the addition of methanol into standard HILIC systems is systematically studied using a select set of acidic, basic, and neutral polar probes. Changes in retention and selectivity of these probes is then interpreted to better understand the impact the alcohol has on underlying HILIC retention mechanisms. Through a better understanding of retention mechanisms, this work promises to aid method developers in intelligently utilizing methanol as an additive as a tool to manipulate analyte retention and selectivity. The results also likely to provide a stronger fundamental picture of HILIC retention mechanisms in general.
