The CK-MB Serum Rapid Test is a sandwich immunoassay. When serum sample is added to sample pad, it moves through the conjugate pad and mobilizes gold anti-CK-MB conjugate that is coated on the conjugate pad. The mixture moves along the membrane by capillary action and reacts with anti-CK-MB antibody that is coated on the test region. If CK-MB is present at levels of 7.0 ng/mL or greater, the result is the formation of a colored band in the test region. If there is no CK-MB in the sample, the area will remain colorless. The sample continues to move to the control area and forms a pink to purple color, indicating the test is working and the result is valid.