Description
Principle of the Assay: CA19-9 ELISA kit applies the competitive enzyme immunoassay technique utilizing a monoclonal anti-CA19-9 antibody and an CA19-9-HRP conjugate. The assay sample and buffer are incubated together with CA19-9-HRP conjugate in pre-coated plate for one hour. After the incubation period, the wells are decanted and washed five times. The wells are then incubated with a substrate for HRP enzyme. The product of the enzyme-substrate reaction forms a blue colored complex. Finally, a stop solution is added to stop the reaction, which will then turn the solution yellow. The intensity of color is measured spectrophotometrically at 450nm in a microplate reader. The intensity of the color is inversely proportional to the CA19-9 concentration since CA19-9 from samples and CA19-9-HRP conjugate compete for the anti-CA19-9 antibody binding site. Since the number of sites is limited, as more sites are occupied by CA19-9 from the sample, fewer sites are left to bind CA19-9-HRP conjugate. A standard curve is plotted relating the intensity of the color (O.D.) to the concentration of standards. The CA19-9 concentration in each sample is interpolated from this standard curve