Disclosed herein are methods, techniques, and processes for enhancing the purity of a mixed rare earth solution. In one embodiment the rare earth mixture may include Lanthanum, Cerium, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Scandium, and/or Yttrium. In one embodiment, the resin is a chelating resin that interacts poorly with one or more rare earth elements. In one embodiment a rare earth is selectively excluded for example, Lanthanum (sometimes considered a transition metal), Cerium, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, Lutetium, Scandium, and/or Yttrium. In one embodiment, yttrium is selectively excluded from the column.