Patent ID: 6699722
Filing Date: 2004-03-02
Classification: G01N

Abstract:
A method for detecting and/or quantitating an analyte in a liquid sample, comprising:(a) providing a test strip comprising a mobilization zone; a mobile or mobilizable detectable tracer in the mobilization zone; a sample application area; a primary capture area comprising a first immobilized binding partner having a binding affinity for the analyte and a binding affinity for the detectable tracer; and a secondary capture area comprising a second immobilized binding partner having a binding affinity for the detectable tracer; wherein the sample application area, mobilization zone, primary capture area and secondary capture area are in a path of liquid flow from the sample application area distally through the mobilization zone to the primary capture area and then to the secondary capture area, wherein a distal flow of analyte reaches the primary capture area before a distal flow of tracer reaches the primary capture area; (b) contacting the liquid sample with the sample application area of the test strip, and allowing the liquid sample to mobilize the detectable tracer such that the detectable tracer migrates with the liquid sample, wherein the detectable tracer has a weight greater than the analyte to permit analyte flow to move at a faster rate than the tracer flow along the path of liquid flow, such that the tracer flow reaches the primary capture zone after analyte flow in the liquid sample reaches the primary capture area; wherein the analyte flow that reaches the primary capture zone occupies first immobilized binding partner such that subsequent binding of detectable tracer to first immobilized binding partner is inhibited, whereby unbound detectable tracer continues along the path of liquid flow distally to bind to second immobilized binding partner and provide a signal from the secondary capture area that indicates the presence of the analyte in the liquid sample.