Disclosed herein are embodiments of matrixes made of a porous size exclusion support and a cationic moiety for separating one or more small molecules from one or more large molecules in a sample using differences in one or more properties such as the size of the molecules, charge of the molecules, the isoelectric point (pI) of the molecules, and/or any combination of these properties including methods, systems, and kit embodiments. Also disclosed herein are embodiments of a method of making the matrixes and using the matrixes for separating small molecules from one or more large molecules in a sample.