Determination of analyte concentration using two labelling markers

Abstract From the Canadian patent

In order to measure the concentration of an analyte in a liquid sample the sample is contacted with a receptor molecule having binding sites for the analyte and labelled with a first marker, whereby a fraction of the binding sites on the receptor molecule become occupied by the analyte, the sample being contacted with such a small amount of the receptor, having regard to its affinity constant with the analyte, that only an insignificant fraction of the analyte becomes bound to the receptor. The receptor having fractionally occupied binding sites is then back-titrated by means of a back-titration technique involving a system including a second marker different from the first, and the …