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-pe rformance liquid chromatography. The method includes the synthesis of 4-(4- carboxybenzyloxy)-3-methyl-2-dodecyloxy-4'-(2-(4'-dodecyloxybenzyl)-ethylen e-azobenzene (ALC) which reacts with LiChrospher Si 100 NH2 to give the bon ded stationary phase (denoted BLC). Characterization of ALC and the BLC wer e performed by differential scanning calorimetry (DSC), proton NMR, solid-s tate C-13 NMR and elemental analysis. The specific surface area of the BLC was determined by BET. The chromatographic behaviour of the BLC was investi gated in both normal and reversed-phase modes. As a normal phase, a tempera ture transition is found in the 315-330 K range which leads to remarkable a nalytical properties. The retention factors of phenanthrene and anthracene increased when the temperature was increased from below to above the transi tion temperature. In the reversed-phase mode, the behaviour of the BLC seem ed more complex, two temperature transitions being apparent. Separation of xylene and diethylbenzene isomers was possible at temperatures above the te mperature range of the transitions.