Abstract: A method of determining an amount of analyte in a sample solution is provided. The method involves the use of an assay device that has a substantially planar assay surface. The surface has a plurality of calibration dots a test dot printed thereon. The calibration dots contain pre-determined quantities of the analyte while the test dot includes a capture antibody for binding to the analyte. The analyte is mixed into a solution having a sample antibody for the analyte, where the antibody is labeled with a detectable marker. The sample solution is introduced into the loading portion of the assay device for delivery to said reading portion. The next step is to measure the intensity of detectable marker in the calibration dots. With the data obtained, one then prepares a calibration curve correlating the amount of analyte in said calibration dots to said intensity of detectable marker.