31,579 Kits for Application ELISA. Enzyme-linked immunosorbent assay (ELISA) is based on an older and very similar technique called enzyme immunoassay (EIA). These immunological assays are biochemical in nature and are used to detect and quantify the presence of an antibody or an antigen in a sample. ELISA assays are applied in various fields of biotechnology and molecular biology and are being used as a diagnostic tool in medicine, as well as a quality control assay in various industries. ELISA