3. Radioimmunoassays

According to their principle, to achieve a good RIA (competition) or IRMA (sandwich) assay, the reagents and the various reaction steps must meet certain conditions:

• the substance, ${\text{Ac}}^{\ast }$ or ${\text{Ag}}^{\ast }$ , must be labelled with an appropriate radio-nuclide (iodine, tritium);

• The Ac antibody used must ensure maximum specificity for the reaction, in particular by using monoclonal antibodies;

• free and bound fractions must be completely separated, so that only the activity of one or the...