New chemically bonded liquid crystal for high-performance liquid chromatography: Synthesis, characterization and chromatographic behaviour

A new bonded liquid-crystal stationary phase has been developed for high-performance liquid chromatography. The method includes the synthesis of 4-(4-carboxybenzyloxy)-3-methyl-2-dodecyloxy-4′-(2-(4′-dodecyloxybenzyl)-ethylene-azobenzene (ALC) which reacts with LiChrospher Si 100 NH2 to give the bonded stationary phase (denoted BLC). Characterization of ALC and the BLC were performed by differential scanning calorimetry (DSC), proton NMR, solid-state13C NMR and elemental analysis. The specific surface area of the BLC was determined by BET. The chromatographic behaviour of the BLC was investigated in both normal-and reversed-phase modes. As a normal phase, a temperature transition is found in the 315–330 K range which leads to remarkable analytical properties. The retention factors of phenanthrene and anthracene increased when the temperature was increased from below to above the transition temperature. In the reversed-phase mode, the behaviour of the BLC seemed more complex, two temperature transitions being apparent. Separation of xylene and diethylbenzene isomers was possible at temperatures above the temperature range of the transitions.