1. Enzyme-linked immunoassay is commonly used in the laboratory to detect antibodies in the blood. Solutions tend to turn into a different color when the targeted antigen and an enzyme come into contact with each other. This test is based on the principle of antigen-antibody interaction. ELISA works by a binding an enzyme-linked antibody specific for the targeted antigen to the target antigen. The presence of the antigen is determined when an enzyme-dependent color change appears. A change to a predetermined color equates to the binding of the antibody to the specific antigen (Janeway, et. al. 2001).
2. A fab fragment is a portion of a specific antibody that binds to antigen (Rupp 1999). This third component, anti-digoxigenin-peroxidase Fab reacts with digoxigenin, resulting to a more specific determination of digioxigeni-labelled compounds in this case, the antibody to Hgh (Roch Diagnostics n.d.)
3. Adding a peroxidase substrate such as (ABTS) with the substrate enhancer can enhance the sensitivity of the assay without altering the capture or detector antibodies or the fab fragment. This is by catalyzing the cleavage of the substrate to yield a particular colored reaction (Roch Diagnostics n.d.).
4. Although radioimmunoassay is widely popular because of its high sensitivity, ELISA is used in clinical settings because aside from its sensitivity, it allows for easier handling of multiple samples without having the need to deal with radioactivity (Radioimmunoassay 2005). In the same way, it is more widely used compared to immunoradiometric assay because of the latter’s necessity for radioactive isotopes. Immunoradiometric assay involves the binding of an radioactive nuclide-labelled antibody (tracer) to the antibody (IUPAC 1994).
5. The concentration of the sample can be determined by determining the absorbance of the sample. The absorbance can be determined using an ELISA reader. A higher absorbance means that there is a higher concentration of HgH present (Roche Diagnostics n.d.).