Carrying out assaying methods involving biospecific reactions

Claim 1

The improvement in carrying out, in the presence of an aqueous liquid, assaying methods involving biospecific affinity reactions in which there are used from two to four reactants, one of which reactants, reactant (I), being labelled with at least one analytically indicatable atom or group and being soluble in the aqueous liquid wherein the biospecific affinity reaction is carried out, said reactants forming by biospecific affinity reactions a conjugate in which labelled reactant (I) is incorporated, and in which methods the analytically indicatable atom or group is assayed in at least one member of the group comprising the conjugate and the labelled reactant (I), which is not bound to the conjugate, which comprises (a) using as at least one of said reactants a reactant which is modified in such a way that conjugate and labelled reactant (I), which is not bound to the conjugate, are asymmetrically partitioned in a system of two immiscible aqueous liquid phases, due to differences in physical affinity of the molecules to at least one of the two phases, which system in addition to water comprises in dissolved form, (i) at least two water-soluble polymers, or (ii) at least one water-soluble polymer at at least one water-soluble salt, or (iii) at least one water-soluble polymer and at least one water-soluble organic solvent, (b) providing said system of two aqueous liquid phases, (c) partitioning of conjugate and labelled reactant (I) which is not bound to the conjugate, in said system of two aqueous liquid phases by the addition thereof to said system and allowing the phases to separate, and (d) assaying the analytically indicatable atom or group in at least one of the phases.