Experimental techniques leaching studies

A third technique that has been used to study colloidal nanocatalysis is the Colhnan test or the 3-Phase Test [16]. One reactant is chemically bound to a solid support (Phase 1) and the catalyst is chemically bound to a second solid support (Phase 2). Phases 1 and 2 are suspended in solution (Phase 3), into which a second reactant is also dissolved (not substrate bound). Direct contact between Phase 1 and Phase 2 is restricted due to the fact they are both substrate bound. If the heterogeneous catalyst in Phase 2 is required for the reaction to proceed there will not be any product formation. If the heterogeneous catalyst (Phase 2) leaches homogeneous complexes into solution (Phase 3), the reaction will proceed and in this way the nature of the active catalyst can be investigated. However, there are limitations to this experimental setup since the formation of products does not rule out heterogeneous catalysis. The formation of secondary particles from leached species is possible, so at best, this test supplies evidence for atomic leaching. 

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