PURPOSE: To perform the specification and quantitative measurement of a segregated substance, that is, a substance preferentially precipitated on the surface of a solid from a liquid and preferentially remaining in the liquid (or eluted to the liquid from the surface of the solid) in the evaluation of the segregation state of a solid-liquid interface.

CONSTITUTION: A receiving stand 2 formed into a shallow cup shape on the upper surface side thereof is provided in a container 1 and, after predetermined inert gas is introduced into the container 1 in a ventilating state, the plate body 3 to be tested placed on the receiving stand 2 is curved by a curving and deforming means such as a vacuum suction mechanism so as to become a recessed shape on the surface side thereof. A predetermined solution is dripped on the plate body 3 to be tested through a fine tube 4 and the dripped solution is evaporated by the lighting of a mercury lamp 7. When predetermined evaporation is completed, the plate body 3 to be tested is taken out of the container 1 and analyzed according to the kind of a segregated substance by an attached measuring apparatus.