Homovanillic and vanilmandelic acid are major catecholamine pathway metabolites. VMA and HVA can be found in urine along with other metabolites. Homovanillic and vanilmandelic acids were separated by combination of weak reversed-phase and anion-exchange mechanisms on the core-shell column. This method can be used for analysis of hydrophilic acidic compounds with LC. MS compatible conditions. Both compounds elute with a good peak shape. Retention time is controlled by amount of acetonitrile, buffer concentration, and buffer pH. Stationary phase does not change its ionization state with the change of buffer pH, but ionization state of acidic compounds is greatly affected by buffer pH.