| abstract |
The present invention provides a method of assay of a ligand in a sample, which comprises incubating, simultaneously or in sequence, (a) the sample (containing the analyte ligand), (b) a directly labelled specific binding partner to the ligand, (c) a ligand analogue as herein defined, conjugated with a reagent X (the said reagent not being present as a free reagent in the mixture); separating, after a suitable incubation period, the portion containing component (c) from the mixture by means of a solid phase carrying a binding partner specific for reagent X; and determining the extent of complexing between components (b) and (c) by measurement of the label. |