Immunoassays are a technology that combines the principle of chemistry and immunology to enable scientific tests. The basic principles of these assays take advantage of the specificity of antibody-antigen reactions.

Some of the most common immunoassays are:

• Chemi- Luminescent Immunoassay (CLIA)
• Enzyme-linked immunosorbent assay (ELISA)
• Fluorescent immunoassay (FIA)
• Radioimmunoassay (RIA)

These immunoassays are widely used for scientific research, in vitro diagnostics, and drug discovery. Immunoassays are a cost-efficient, highly specific method for the detection of molecules not detectable by other techniques.

CLIA is well established as one of the most efficient alternatives to classical RIA or conventional ELISA tests, for the quantification of low concentrations of analytes in complex samples.

Since CLIA is both non-isotopic and non-toxic, the scope of this type of analytical procedure has widened. Clinical chemistry laboratories and other fields – microbiology, veterinary medicine, agrofood, and environmental testing  –  are performing this assay.

The quantitative determination of individual human proteins in biological fluid  – blood, plasma, serum, urine or cerebrospinal fluid  – serves as an important tool not only in diagnosing diseases, but also in monitoring the course of a disease and the effect of the treatment.

Using competitive or non-competitive tests is inducing by the analyte size, such as hormone, vitamins and others.