Lateral flow test kit and method for detecting an analyte

A method for the analysis of a liquid sample for the presence of an analyte comprising the steps of:

• a) contacting the sample with a receptor to form a mobile phase, the receptor characterized by an ability to bind to the analyte to provide, in the mobile phase, a receptor-analyte complex;
• b) contacting the mobile phase with a solid support, the solid support configured to allow lateral flow of the mobile phase to a first test area, a second test area and a control zone, the first test area, the second test area and the control zone configured on the solid support in a spaced apart relationship and each comprising a capture agent immobilized on the solid support, the first and the second test area capture agents characterized in that the capture agent has greater binding affinity to the receptor than to the receptor-analyte complex, the control zone capture agent characterized in that the affinity to the receptor is equivalent to the affinity to the receptor-analyte complex, the solid support configured to allow the mobile phase to flow from the first test area to the second test area on the solid support and from the second test area to the control zone on the solid support;
• c) prior to, currently with, or subsequent to steps (a) and (b), tagging the receptor with a label, the label characterized in that it provides a detectable signal when the receptor is bound to any of the first test area capture agent, the second test area capture agent and the control zone capture agent;
• and
• d) measuring the intensity of the detectable signal at each of the first test area, the second test area and the control zone,
• wherein the intensity of the detectable signals in the test areas are inversely related to a concentration of the analyte in the sample.