| Two novel chromatography stationary phases for HPLC were evaluated for their properties and separation capabilities. The two stationary phases, cholesterol and 4-methoxy-4-allyloxy benzoate (MPAB), are liquid crystals, which give the columns unique and interesting properties. Some properties are molecular recognition capabilities, separation of chiral molecules, separation of steroids, the ability to use highly aqueous mobile phases, and non-linear retention with temperature change. Active pharmaceutical ingredients (APIs) were obtained from the pharmaceutical company Roche Palo Alto, LLC and used as analytes. Molecular classes tested include nucleoside analogues, purines, anthracenes, steroids and polar compounds. The cholesterol columns showed high selectivity for planar pro-drugs of nucleoside analogues as compared to a C8 stationary phase. Chiral separations could not be demonstrated with the chosen solutes and mobile phase conditions. In addition, the aqueous normal phase (ANP) mode of chromagraphy was demonstrated on some analytes using specific mobile phase conditions. |
