ABSTRACT
The terms “competitive” and “sandwich” of the two immunoassay types are descriptive of each assay procedure. In competitive immunoassay, an aliquot of enzyme-labeled antigen (Ag*) of known concentration is added to the sample for competitive binding to the primary antibody. Following this, the reaction surface is rinsed and the enzyme substrate (S) added. After allowing sufficient time for enzymatic conversion, the sample is analyzed for the electroactive enzyme product (P). The concentration of P bears an inverse relationship to the analyte (Ag) concentration because of the competitive binding of Ag*.
