The simultaneous precipitation of a normally soluble component with a macro-component from the same solution by the formation of mixed crystals, by adsorption, occlusion or mechanical entrapment.
Orange Book, p. 86
See also:
PAC, 1979, 51, 1195 (Separation and preconcentration of trace substances. I - Preconcentration for inorganic trace analysis) on page 1199