Simultaneous separation of polar and non-polar mixtures by capillary HPLC based on an ostadecylsilane and taurine derivatized silica continuously packed column - ScienceDirect
InertSustain AQ-C18 LC Columns, best AQ column available, made in Japan.
Mixed-Mode Chromatography—A Review
HPLC Analysis of Polar Compounds on Ascentis® Express RP-Amide Particles application for HPLC | Sigma-Aldrich
Hypersil GOLD™ PFP HPLC Columns
Polar Compound Retention using Aqueous Normal-Phase (ANP/HILIC) Chromatography