What are the common types of immunochemical techniques used in biochemistry?

Immunochemical techniques encompass various processes used to detect the distribution of a target antigen or protein in tissues or cells. These techniques are based on the highly specific affinity of an antibody for its antigen. 

The 7 most common types of immunochemical techniques used in biochemistry include: 

1. Immunoassay: Immunoassay is a laboratory technique used to determine the concentration of a particular substance in a biological fluid such as urine or serum. It is based on the specific binding of an antigen to its antigen. Immunoassays play an integral role in the HIV test used to diagnose HIV. 
2. Radioimmunoassay: Radioimmunoassay is among the most sensitive techniques used for detecting antigens or antibodies. It is based on the competitive binding of radio-labeled antigen and unlabeled antigen to a high-affinity antibody. Because of its high sensitivity, this procedure is well suited for measuring the concentration of substances such as serum proteins, hormones, vitamins, and drugs at concentrations as low as 0.001 micrograms per milliliter or even less.   
3. Enzyme-Linked Immunosorbent Assay: More commonly known as ELISA, this immunoassay technique serves two purposes – detecting the presence of antibody or antigen and measuring serum antibody concentrations. It works on a similar principle as radioimmunoassay but uses an enzyme instead of a radioactive label. 
4. Immunohistochemistry: Immunohistochemistry or IHC is a staining technique widely used to diagnose and treat cancer and to study the distribution and localization of biomarkers in various parts of a tissue. It works by localizing proteins in cells of a tissue section using the principle of specific binding between antibodies to antigens in biological tissues. 
5. Immunoelectrophoresis: A strictly qualitative technique, immunoelectrophoresis is used to determine the presence or absence of proteins in the serum sample. Its use is limited to detecting abnormally high antibody concentrations greater than several hundred mg/ml, which is characteristic of certain immunodeficiency disorders. 
6. Immunoprecipitation: Immunoprecipitation is a sensitive assay used to detect the presence of a particular antigen in a given type of cell or tissue by forming a precipitate of an antigen-antibody complex. This technique is also used to isolate the antigen of interest for further analysis. 
7. Immunofluorescence: Immunofluorescence is an immunoassay technique that involves labeling antibodies with molecules that have the property of fluorescence, enabling their detection by colored light emission when excited by light of the appropriate wavelength. Immunofluorescence is useful for detecting Ag-Ab complexes in autoimmune disorders, localizing hormones stained in situ, and identifying bacterial species and subpopulations of lymphocytes.