摘要 |
<p>A biological sample containing an analyte, partly free and partly bound to natural binders, is incubated with a labelled specific binder for the analyte and a derivative of the analyte which does not react with the natural binders. Part of the labelled specific binder binds to the analyte derivative, the proportion depending on the free analyte concentration in the sample. The proportion is measured and used to determine the free analyte concentration. For example, the analyte may be thyroxine or cortisol, the labelled specific binder may be an antibody thereto, and the analyte derivative may be in the form of a solid matrix. The labelled specific binder should have an affinity for the analyte, expressed as a dissociation constant of the complex of the two, approximately equal to the concentration of free analyte in the sample.</p> |