The present application provides a two phase immiscible system for the pretreatment of embedded biological samples comprising placing at least one support having an embedded biological sample on its surface into a pretreatment container, adding to 5 the pretreatment container at least one reagent forming a layer, adding a carrier composition to the pretreatment container, such that reagent forming layer is formed on the top of the carrier composition, and in an amount such that the at least one reagent forming layer contacts at least a portion of the embedded biological sample. Pretreatment of the embedded biological samples can include removal of embedding medium from embedded biological, target retrieval and enzyme blocking samples before staining histochemical analysis or other processes. The system also includes an apparatus and processes of automation of the pretreatment methods.