Patent ID: 7108993

Claim:
A device for determining the amount of an analyte in a fluid test sample containing heterophilic antibodies which non-specifically bind to antibodies used to capture and immobilize labeled antibodies, said device comprising a test matrix having: (a) a first region for receiving said sample, said first region containing a first anti-analyte antibody conjugated with a detectable label and one part of a specific binding pair; said first region further containing an amount of an immunoglobulin from the same animal source as said first anti-analyte antibody sufficient to prevent non-specific binding of said heterophilic antibodies in the second region; (b) a second region for receiving said sample from said first region and capturing and immobilizing said first anti-analyte antibody bound to an analyte in said sample, said second region containing an immobilized second anti-analyte antibody which is specific for a different epitope of said analyte than said first anti-analyte antibody; (c) a third region for receiving said sample from said second region and trapping the portion of said first anti-analyte antibody not bound to said analyte, said third region containing an immobilized second part of said specific binding pair of said first region; and (d) an absorbent region for receiving said sample from said third region.