Time‐dependent column performance of cholesterol‐based stationary phases for HPLC by LC characterization and solid‐state NMR spectroscopy

Abstract

Three different cholesterol-based stationary phases were investigated with respect to their time-dependent separation behavior. The examined stationary phases differ in the used spacer molecule and the synthesis route and were used under routine laboratory conditions over a period of two years. The chromatographic behavior of the three phases was determined by using a standard reference material in addition to a separation of a steroid mixture. The surface chemistry and the modification of these with the chemically bonded moiety were investigated with nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Through applying different techniques we determined changes in retention and selectivity; solid-state NMR spectra showed changes in the surface chemistry dependent on the synthesis route. Superior long-term stability was observed for the undecanoate-cholesterol (UDC-Chol) column in terms of hydrophobic retentiveness and selectivity.

Cholesterol-based polymeric monolithic columns for capillary liquid chromatography

“…Throughout the silanization procedures, silica surface can be modified by organo-silanes. The cholesterol molecule may be directly attached to the Si-H group [12], silanization procedures or to the different linkage molecules, e.g. amino- [8] or diamino-bonded ligand [19].…”

“…The most important advantage of the cholesterol stationary phase is that it can be successfully used in both normal-and reversed-phase liquid chromatography. The compounds resolved include, e.g., antibiotics [5], benzodiazepines [6], flavonoids [7], polycyclic aromatic hydrocarbons (PAHs) [1,[8][9][10], steroids [11][12][13], beta-blockers [14,15] and different xenobiotics [4]. Additionally, commercially available cholesterol-based chromatographic columns (Cosmosil Cholester and Cogent TM UDC-cholesterol) were used in other applications, e.g., separation of catechins, saikosaponins, carotenes, vitamin K isomers [16,17].…”

The Development of Silica Hydride Stationary Phases for High Performance Liquid Chromatography from Conception to Commercialization

“…The remainder of the features in the spectrum are the result silicon-oxygen matrix vibrational frequencies. Another useful spectroscopic technique is cross-polarization magic-angle spinning (CP-MAS) nuclear magnetic resonance (NMR) [29][30][31]. This method results in the NMR spectrum of the surface of solid particles such as typical chemically modified chromatographic supports.…”

The Development of Silica Hydride Stationary Phases for High-Performance Liquid Chromatography from Conception to Commercialization

“…The remainder of the features in the spectrum are the result of silicon-oxygen matrix vibrational frequencies. Another useful spectroscopic technique is cross-polarization magic-angle spinning (CP-MAS) nuclear magnetic resonance (NMR) [30][31][32]. This method results in the NMR spectrum of the surface of solid particles such as typical chemically modified chromatographic supports.…”