Immunochromatographic assay system and method

A method for detecting the presence of a specific analyte in solution comprising the steps of:

• affixing to an elongated chromatographic medium having a longitudinal axis a first antibody which binds with specificity to said analyte, said first antibody disposed on said chromatographic medium in a pattern which forms a predetermined geometric symbol or symbols consisting of a plurality of line segments, said line segments including a first line segment substantially parallel to said longitudinal axis and a second line segment substantially perpendicular to said longitudinal axis;
• partially blocking or obstructing the expected passage of a moving phase or solvent using at least one partial obstruction to direct said moving phase or solvent through said symbol or symbols on said chromatographic medium in a direction other than parallel to said longitudinal axis, wherein said at least one partial obstruction is positioned immediately upstream or immediately downstream or lateral to said predetermined geometric symbol or symbols;
• reacting said solution to a marker-second antibody complex which binds with specificity to said analyte to form analyte-marker-second antibody complexes in the presence of said analyte;
• eluting said solution containing any said analyte-marker-second antibody complex around said at least one partial obstruction;
• and;
• observing the substantially complete formation, or lack thereof, of the predetermined geometric symbol or symbols by means of said marker.