Back Cover: Separation of pharmaceutically active compounds by multimodal chromatography with ultraviolet detection

Abstract

The cover picture shows the retention behavior of positively charged thiamine and basic cytosine in mobile phases with three different buffer types at low and high acetonitrile (ACN) content on three different mixed-mode columns. All three columns contain the same C18 hydrophobic moiety and differ only in the hydrophilic parts (HILIC-1, WAX-1 and WCX-1). The effect of the buffer type on the retention is significantly affected by ACN content as well as the chemical structure of the analytes and columns. While differences in cytosine retention at low and high ACN content are comparable for all buffers tested, unexpectedly long retention is observed for thiamine at high ACN content, especially in combination with phosphate buffer.