Patent ID: 8101429

Claim:
A lateral flow sandwich assay device for detecting the presence of an analyte in a liquid sample, said assay device comprising: (a) a first region comprising a diffusibly bound labeled reagent complementary to an analyte in the liquid sample, wherein said diffusibly bound labeled reagent and said analyte form a diffusible first complex; (b) a test region comprising a non-diffusibly bound capture reagent capable of complexing with the first complex such that said analyte is bound between said non-diffusibly bound capture reagent and said diffusibly bound labeled reagent; (c) a control region comprising a non-diffusibly bound control reagent complementary to the diffusively bound labeled reagent and (d) a reference region comprising a predetermined concentration of non-diffusibly bound analyte that will complex with said diffusibly bound labeled reagent upon operation of the device to form a complex having a predetermined signal intensity, said non-diffusibly bound analyte having substantially the same affinity for said diffusibly bound labeled reagent as said diffusibly bound labeled reagent has for said analyte in the liquid sample such that any influences on the interaction and binding of analyte and diffusibly bound labeled reagent in said first region would be similarly encountered in the interaction and binding of said non-diffusibly bound analyte with said diffusibly bound labeled reagent in said reference region such that said predetermined signal intensity can serve as a_reference to indicate, by a comparison of the actual signal intensity of said reference region to said predetermined signal intensity, the presence of interferants that negatively impact the interaction and binding of analyte and diffusibly bound labeled reagent in said first region.