Partition affinity ligand assay (PALA): radioimmunoassay of digoxin

A new approach to radioimmunoassay is described. Thanks to the use of an aqueous two-phase system for separation of bound and free ligand, a convenient procedure has been developed where soluble antibodies may be used and separate washing steps are unnecessary. Assay of digoxin in serum using the Partition Affinity Ligand Assay (PALA), gave results which correlated closely (r = 0.979) with those obtained with conventional RIA-procedures.