Patent ID: 7517699

Claim:
A method of making a lateral flow chromatography test strip to determine a presence and/or amount of an analyte in a liquid sample, wherein the test strip comprises: a mobile or mobilizable detectable tracer area comprising a mobilizable tracer; a sample application area for applying a liquid sample; a primary capture area comprising a first binding partner; a secondary capture area comprising a second binding partner; wherein the sample application area distally through the detectable tracer area to the primary capture area and then, detectable tracer area, primary capture area and then, detectable tracer area, primary capture area and secondary capture area are in a sequential path of liquid flow along a bibulous substrate that permits separation of components as they flow along the strip, wherein the path of liquid flow extends from the sample application area to the secondary capture area, and the tracer has a physical characteristic that provides specific migration characteristics, that delays arrival of the tracer at the primary capture area relative to the analyte after the liquid sample is placed on the sample application area, such that the tracer reaches the primary capture area after the analyte, and the tracer provides a signal in the secondary capture area that is proportionate to an amount of analyte in the liquid sample, wherein the method of making the lateral flow chromatography test strip comprises selecting the mobilizable tracer to slow migration of the tracer along the lateral flow chromatography test strip relative to the analyte so that the tracer and analyte separate before the analyte reaches the primary capture area, and selecting the mobilizable tracer comprises selecting the tracer to have a specific physical characteristic that delays arrival of the tracer at the primary capture area relative to the analyte, wherein the specific physical characteristic comprises a polarity, charge or size that interacts with the lateral flow chromatography test strip to delay arrival at the primary capture area.