1989 Volume 36 Issue 5 Pages 641-646
A competitive, double antibody enzyme immunoassay for oxytocin in a heterologous system was developed. Horseradish peroxidase was conjugated with oxytocin using N-succinimidyl 3-(2-pyridyldithio) propionate, and rabbit anti-oxytocin serum was produced by immunization of oxytocin-bovine serum albumin complex which was prepared by the carbodiimide method.
The sensitivity of the assay was 4 μIU/tube, which corresponded to 10μIU per ml using 400μl of the sample which was extracted from the same volume of plasma by means of SEP-PAK C18 cartridges.
The coefficients of variation for different levels of oxytocin ranged from 6.8-15.9% and 8.5-16.7%, for intra- and inter-assay. Recovery of oxytocin added to plasma after extraction was 99-117%.
No or little cross-reaction with arginine-and lysine-vasopressin was found.
Plasma oxytocin concentrations determined by the proposed enzyme immunoassay were well correlated with those determined by radioimmunoassay (r=0.90).
