A series of four-mixed mode ion exchangers for SPE, consisting of either weak or strong cation or anion exchangers, have been synthesized by functionalization of spherical, porous particles made from a copolymer of N-vinylpyrrolidone and divinylbenzene. These materials are able to selectively retain and release acidic and basic solutes through the judicious choice of wash solvent pH, as shown through the use of SPE recovery tests.