This assay employs the competitive inhibition enzyme immunoassay technique. The microtiter plate provided in this kit has been pre-coated with antigen. Standards or samples are added to the appropriate microtiter plate wells with an antibody specific for ABA. The competitive inhibition reaction is launched between with pre-coated ABA and ABA in samples with the antibody. Then add a Horseradish Peroxidase (HRP) conjugated goat-anti-rabbit IgG antibody. A substrate solution is added to the wells a