One-step process for preparation of polar/non-polar copolymerized stationary phases by using surface horizontal polymerization

Reversed-phase liquid chromatography (RPLC) is the most popular chromatographic mode for the separation of a wide variety of compounds. The traditional alkyl stationary phases for RPLC primarily complement hydrophobic interaction, while the polar interactions are limited. Polar RPLC stationary phases are developed to enhance the polar interactions in the RP separation of polar compounds. So far, there are two main approaches, e.g. polar embeded and polar endcapped, for the introduction of polar groups in RPLC stationary phases. 1 Herein, a new approach with one-step process for preparation of polar stationary phases for RPLC was proposed. In this approach, the mixture of polar silane (e. g. 3-chloridepropyltrichlorosilane) and non-polar silane (e. g. n-octadecyltrichlosilane) are copolymerized on the silica surface to afford the “polar/non-polar copolymerized stationary phase” (Figure 1) by using horizontal polymerization silanization method, which was introduced by Wirth and coworkers. 2 This new approach is facile and flexible. The types and ratios of the polar and non-polar silanes can be used for preparation of well designed stationary phases. The polar/non-polar copolymerized stationary phases demonstrated good separation efficiency and selectivity in the separation of test standards, tryptic digests of bovine serum albumin and several kinds of Traditional Chinese Medicines (TCMs).