Abstract: Disclosed is a method for determining the concentration of an analyte in a sample of body fluid. The method involves contacting the body fluid sample with a test strip containing mobile, labeled specific binding partner for the analyte, through which strip the test fluid, analyte and any complex formed by interaction of the analyte and labeled specific binding partner therefore can flow by capillarity. The strip contains at least one zone for capture of the labeled specific binding partner and at least one separate zone for retention of the analyte/labeled specific binding partner complex. By determining the magnitude of the signal from the detectable label in the capture zone(s) and retention zone(s) and determining a final response signal by correlating signals using an algorithm and number of zones chosen in a manner that provides a final response signal best suited for the particular assay, the concentration of the analyte can be determined with greater precision.

Abstract: Disclosed is a device and method for carrying out an assay for an analyte in a fluid test sample by immunochromatography. The device involves a strip having a non-porous receiving member of a hydrophobic material in direct fluid communication with a reagent region of an absorbent material through which the fluid test sample can flow by capillarity. By applying the fluid test sample to the non-porous hydrophobic receiving member rather than directly to the absorbent material the reliability of the assay is enhanced.