1. (in an ion exchanger) The mobile exchangeable ions.
    PAC, 1993, 65, 819. 'Nomenclature for chromatography (IUPAC Recommendations 1993)' on page 854 (
  2. (in colloid chemistry) Ions of low relative molecular mass, with a charge opposite to that of the colloidal ion.
    PAC, 1972, 31, 577. 'Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry' on page 607 (