Abstract: An apparatus in the form of a test strip is useful for determining the presence of one or more components in a fluid sample. The test strip can be used by itself or in conjunction with an associated housing assembly. The test strip provides a rapid volume, timing and temperature independent visually readable strip for the semi-quantitative detection of a component, such as an analyte.

Abstract: A test strip holder includes an elongated hollow member having an open end and a closed end. A support is provided that positions a test strip within the elongated hollow member spaced from inner walls of the elongated hollow member. At least one vent is positioned between the open end and the closed end of the elongated hollow member. The distance from the open end to the at least one vent opening defines the maximum height of liquid able to enter the elongated hollow member from the open end other than by capillary action. The elongated member may be formed as a tubular conduit. Alternatively, the elongated member may include a test strip receiving part and a test strip covering part, wherein the test strip receiving part may or may not be hingedly connected to the test strip covering part.

Abstract: A method for obtaining a substantially pure preparation of an enzyme-antibody conjugate having an enzyme component covalently coupled to a predetermined number of an antibody component where the molecular weight of the enzyme component is substantially greater than the molecular weight of the antibody component. The method involves the electrophoretic separation of the desired enzyme-antibody conjugate from an enzyme-antibody conjugate reaction mixture comprising, as separately migratable species, at least a free enzyme component and a poplulation of enzyme-antibody conjugates comprising one or more of the enzyme component convalently coupled to one or more of the antibody component. The resulting conjugate preparations are substantially pure and are therefore particularly useful as labeled reagents in immunometric assays.

Abstract: A method for obtaining a papain-free F(ab').sub.2 antibody fragment preparation derived from papain digested whole IgG antibody employing an antibody to papain for binding to and removing papain-associated digestion products from the preparation. The method is particularly useful for digesting whole IgG antibodies which are otherwise sensitive to pepsin digestion to provide F(ab').sub.2 antibody fragments from which Fab' antibody fragments can be obtained having available free sulfhydryl groups in the hinge region.