Abstract: A disposable, pre-packaged device for conducting an immunoassay procedure that results in the production of separable liquid and solid phases. The device includes a cup having an inlet and presenting a liquid phase receiving chamber. An absorbent for liquid phase materials is in the chamber and a series of ribs hold the absorbent away from the walls of the chamber providing a breathing space extending around the absorbent. A porous capture media element for capturing and displaying solid phase products of the procedure is disposed adjacent the inlet of the device in fluid communication with the absorbent so that in operation the absorbent promotes flow of liquid phase through the capture element. A lid element is mounted on the cup adjacent the inlet and the lid and the cup are held together by welding of annular flanges. The lid element includes an elongated cylindrical member extending through the inlet and defining a throat for directing flow of liquid phase onto the capture media.