Patent ID: 6844200

Claim:
A device for detecting the concentration of a target analyte in a sample of body fluid relative to the concentration of a reference analyte in the same sample of body fluid which comprises: i. a strip of absorbent material through which the test sample can flow which strip contains: a) a first zone which contains reagents for colorimetric determination of the reference analyte; b) a second zone containing a releasable specific binding reagent for the target analyte which specific binding reagent bears an attached detectable label and forms an analyte/labeled specific binding partner reagent upon contact with the body fluid sample containing the target analyte; and c) a third region which contains an immobilized capture reagent for specifically binding the analyte or labeled specific binding reagent for the analyte; and ii. a hollow casing having a top and bottom segment enclosing the strip of absorbent material which casing has a body fluid inlet port directly above and in visual and fluid communication with the first zone of the strip of absorbent material and one or more view ports for detecting the amount of detectable label captured in the third region wherein the hollow casing has a U shaped body fluid impervious barrier which surrounds three sides of the first region of the strip thereby allowing a sample of body fluid applied to the first region of the strip through the inlet port to flow only in the direction of the second and third regions.