Patent ID: RE39664

Claim:
A test device for determining the presence or amount of an analyte substance in a sample by means of one or more specific binding reactions comprising: a bibulous chromatographic medium which extends throughout said device and is free of chromatographic transport- facilitating agent , defining a flowpath having capillarity and the capacity for chromatographic solvent transport of one or more reactive sample components and non-immobilized reagents; said chromatographic medium comprising (1) a prefiltering zone; (2) a reaction site zone disposed downstream from said prefiltering zone at which is present containing an immobilized reagent capable of binding which specifically binds a member selected from the group consisting of said analyte substance and a labeled specific binding material, and at which the presence or amount of immobilized specific binding material, may be is capable of being detected; and (3) a downstream zone free of said immobilized reagent disposed downstream from said reaction site zone , a sample application means selected from the group consisting of a single undivided well and an absorbent pad defined by a housing element comprising an upper and lower portion; wherein said upper portion defines the spatial boundaries of said well and said lower portion comprises a portion of said chromatographic medium which is upstream of said prefiltering zone, said well having sufficient capacity to hold a volume of sample for chromatographic movement of said volume of sample from said well to a liquid absorption means, said well being located adjacent to and disposed in fluid contact with said prefiltering zone of said chromatographic medium and offset upstream from said reaction site zone , and said liquid absorption means consisting of a quantity of blotter material disposed in fluid contact with said downstream zone of said chromatographic medium and offset downstream from said reaction site zone .