Patent ID: 7491551

Claim:
A method of determining an amount of an analyte in a sample, wherein the analyte is a member of a specific binding pair (sbp member), comprising: providing a lateral flow matrix which defines a flow path and which comprises in series, a sample receiving zone, a labeling zone and at least first and second serially oriented capture zones, wherein the labeling zone comprises a diffusively bound labeled first sbp member that is complementary to the analyte whereby the first spb member and the analyte form an analyte-first spb member complex, the first capture zone comprises a second sbp member immobilized therein which is capable of binding the analyte-first sbp member complex with a first affinity, and the second capture zone comprises a third sbp member that is capable of binding the analyte-first spb member complex with a second affinity, the second affinity being different from the first affinity; contacting the sample with the sample receiving zone, whereby the sample flows along the flow path; observing a pattern of label that accumulates at the one or more capture zones; and correlating a pattern of label accumulated in the one or more capture zones to the amount of analyte in the sample.