Affinity chromatographic method for the extraction of ocytocin from human and rat plasma

A procedure based on affinity chromatography for the extraction of ocytocin is described. Ocytocin antibody, covalently attached to a magnetizable iron suspension, retains its ability to bind ocytocin from blood plasma. The conjugate can be reused several times. Recovery of ocytocin was 60-70%, and the detection limit for the extraction assay was about 1 pg per tube. The specificity of the extraction method was characterized by HPLC/RIA on specimens extracted from blood plasma. The extracted material was found to be chomatographically identical with the reference ocytocin preparation. Comparison of RIA data for the same samples extracted by immunoextraction (y) and adsorption (x) showed a linear regression of y = 0.83 x + 2.12, r = 0.81, n = 17.