Abstract: The binding site on an immunoglobulin for a protein is blocked by hydrophobically coupling the immunoglobulin to a blocking agent such as a label. This results in a detection reagent useful in a variety of test assays in which a protein and an immunoglobulin are advantageously used together, but separately. The reagent is useful in the simultaneous determination of IgG and one of IgA or IgM. Anti-IgA-IgG or anti-IgM-IgG is coupled to a hydrophobic label, particularly a pigment or dye, which label blocks the binding site on IgG for Protein A, and labeled Protein A is added.

Abstract: A delivering member for filtering and delivering a sample to a test assay surface includes a prefilter having a sample receiving surface and a surface for delivering a sample to a test assay surface. The prefilter includes a diffusing material on its receiving surface for rapidly and evenly diffusing a sample across the prefilter receiving surface. In this way, a sample may be rapidly and evenly delivered to a test assay surface. A test assay solid phase has a surface including an area carrying an immobilized species and an area free of immobilized species. When a sample is applied to the surface, followed by application of a labeled species, the evenness of distribution of the labeled species is indicative of the evenness of application of the sample. A kit includes a delivering member and an assay surface.