A general study of the binding and separation in partition affinity ligand assay. Immunoassay of beta 2-microglobulin

Partitioning in aqueous 2-phase systems was used to separate free and bound ligand in an immunoassay for beta 2-microglobulin. In order to get efficient separation in the phase system, the antibodies were modified to favour their partition in a different phase from that of antigen. However such modification of antibodies significantly decreased their binding capacity. This was overcome by using antibodies bound to previously modified staphylococci, which had proper partitioning behaviour. Alternatively, antibodies conjugated with biotin could be used in combination with modified avidin. This paper presents a method for the evaluation of data from immunoassays whereby 2-phase systems have been used to separate free and bound antigen.