fig7 and 8 is constructed with a cylindrical base member 80 provided with a plurality of pass through ports or openings 82 and defines a membrane disk seat 84 a cylindrical skirt 86 is integrally formed on the base member 80 which has a diameter substantially the same as rim 65 in order to provide a tight friction fit for attachment of the test assembly to the rim an 34 o 34 ring 88 rests on top surface 81 of base member 80 abutting the inner surface of the skirt 86 to provide a fluid tight seal between the skirt 86 and rim 65 a test disc 71 comprising a solid plastic base member 74 with a handle tab 75 and a membrane member 72 provided with immobilized ligand is seated on the base member 80 inside the ports 82 the circular membrane 72 is glued to the base member 74 or takes the form of a coating the captured antibodies are immobilized on the matrix 72 by a procedure known as solid phase immobilization of the antibodies the tab handle 75 allows the disc 71 to be picked up from the seat b4 without destroying any of the test antigens captured on the disc this allows the disc to then be inserted into a reflectometer color reader for accurate quantification of the test result it is also envisioned that the test handle can be marked with marking.