Background: ELISA is a simple and highly sensitive method of analysis that allows for simultaneous and rapid quantification of a large number of specimens. The assay is based on the specific recognition of the target compound (analyte/antigen) by antibodies which bind to the compound. The antigen-antibody complex is detected and measured with the aid of an enzyme-labeled antibody or antigen. Upon addition of a non-colored reagent, the enzyme produces a color reaction where the color intensity is