A reversed-phase/hydrophilic interaction mixed-mode C18-Diol stationary phase for multiple applications

• A mixed-mode RPLC/HILIC chromatographic stationary phase, C18-Diol, was synthesized.
• C18-Diol was compatible with the pure aqueous mobile phase with excellent stability.
• The switch between RPLC and HILIC was easy by adjusting mobile phase constitution.
• An online 2D-LC-1C system succeeded in fingerprinting of Lonicera. japonica.
• It was suitable for complex sample containing both the polar and nonpolar components.

A mixed-mode chromatographic packing material, C18 and diol groups modified silica (C18-Diol), was prepared with controllable hydrophobicity and hydrophilicity. It demonstrated excellent aqueous compatibility and stability in aqueous mobile phase; compared to the traditional C18 column, improved peak shape of basic analytes was also obtained. Additionally, it exhibited both reversed-phase liquid chromatographic (RPLC) and hydrophilic interaction chromatographic (HILIC) performance; the analyte separation scope was thus enlarged, demonstrated by simultaneous separation of twenty acids, bases and neutrals. More interestingly, a novel on-line two-dimensional liquid chromatography on the single column (2D-LC-1C) was established by modifying the high performance liquid chromatographic instrument only with the addition of an extra six-port two-position valve. The early co-eluted components of the extract of Lonicera japonica on the 1st-dimension (RPLC) were collected for the online re-injection to the 2nd-dimension (HILIC) by conveniently varying the mobile phase components. Six more peaks were obtained. The established system was simple, easy operation and low cost, which had advantages in analyzing complicated samples.

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