| RID | Radial Immunodiffusion | (RID) is a quantitative variation of the Ouchterlony technique (immunodiffusion) in which the agar gel contains evenly distributed antigen (or antibody) and its counterpart from the test sample diffuses into the gel from a single well resulting in a circular precipitin line around the sample well. The diameter of the precipitin ring is proportional to the concentration of the antibody (or antigen) present in the test sample. By comparing the diameter of the test specimen precipitin ring to known standards, a relatively insensitive estimation of the concentration of specific antibody or antigen can be achieved. |