Empore™ Chelating Disks provide a way to selectively remove multivalent metal cations from solutions. This selectivity can be used to concentrate metals from a sample for analysis or to isolate and remove metal interferences from a complex organic or inorganic sample matrix. In the latter case, the purified filtrate is ready for use. The chelating disk has an affinity for multivalent (primarily 2+ and 3+) transition elements. The functional group exhibits differing ionic charges depending on the pH of the solution. At pH 2, the carboxylate groups are neutral and the nitrogen has a net positive charge. This allows the sorbent to function as a weak anion exchanger. Increasing the pH ionizes the carboxylate groups and at pH =5, both are negatively charged. As the pH approaches neutral, the sorbent functions as a cation exchanger or a chelating resin.