Evaluation of various HILIC materials for the fast separation of polar compounds

In recent years, numerous works have been reported on hydrophilic interaction chromatography (HILIC) columns, but there is a growing demand for fast separations with improved resolution. Such analyses can only be obtained with the new generation of columns and instrumentation. In the present study, HILIC columns packed with porous sub-2 mu m particles or with superficially porous particles of 2.7 mu m were evaluated. A set of 15 compounds with diverse physicochemical properties was selected. The aim of this study was to compare the chromatographic behavior of three selected columns. Concerning kinetic performance, the fused-core column offers a backpressure two times lower than the sub-2-mu m particle columns. However, these superficially porous particles also generated a 30% lower efficiency. The complex mechanism of HILIC was also investigated on bare silica columns, confirming that the mechanism is a mixture of partitioning, adsorption and ion exchange in different proportions according to the nature of the analytes, the composition of the mobile phase and the characteristics of the analytical support. Finally, a rapid separation of three drugs and their corresponding metabolites was carried out. The analysis time was reduced to less than 4 min while maintaining acceptable backpressure and sufficient resolution.