SiELC Primesep P is a mixed-mode HPLC column that embeds both aromatic and acidic ion-pairing groups on a short carbon chain. It provides improved retention of basic compounds through a cation-exchange mechanism, differentiates aromatic compounds based on the variations in pi-pi interaction, and retains neutral compounds using a reversed phase mechanism. Depending on analyte properties, one, two, or all three interactions can be applied to the separation. Primesep P is particularly useful for the separation of structural isomers of aromatic compounds and the degree of pi-pi interaction can be adjusted by varying the amount of acetonitrile in the mobile phase.