Poly(4-vinylpyridine) based novel stationary phase investigated under supercritical fluid chromatography conditions

A novel poly(4-vinylpyridine) based stationary phase was investigated for its performance under supercritical fluid chromatography (SFC) mode. Due to its unique structure, this stationary phase has high molecular planarity recognition ability for aromatic samples possessing the same number of aromatic rings and π-electrons. Taking advantage of the planarity recognition ability observed, separations of structurally similar polycyclic aromatic hydrocarbons and steroids were achieved. This novel stationary phase afforded good peak symmetry for both acidic and basic active pharmaceutical ingredients even when excluding the use of additives such as acids, bases, and salts. These findings may be attributed to the polymeric pyridyl groups covalently-attached on silica gel, which will effectively shield the undesirable interaction between residual silanol groups on the surface and the analytes. Moreover, the properties of pyridyl group on the selector can be reversibly tuned to cationic pyridinium form by eluting trifluoroacetic acid containing modifier. Column robustness toward cycle durability testing was also confirmed.