Abstract: An assay cartridge which has a substantially rectangular base plate, a substantially rectangular top plate, and four side walls. The top plate has a plurality of aligned adjacent reaction wells located on its top side. Each well has a hole at its bottom which opens into a waste reservoir which is the space inside of the base plate, top plate and four walls. A filter membrane is positioned against the underside of the top plate covering the well holes. A port through the base plate allows reducing the pressure in the waste reservoir relative to the pressure over the wells for drawing the liquid phase of a reaction from the well through the filter and into the waste reservoir.

Abstract: A method is provided for solid phase immunoassay for quantitation of antigen, hapten or antibody analyte in liquid sample and alternatively for quantitation of analyte occuring on or attached to cells or other particulate material in a liquid sample. The solid phase is suspended for at least the initial reactions and is subsequently concentrated by microfiltration to a volume substantially less than the sample volume. Luminescence of substantially the entire label on the concentrated solid phase is measured.