Abstract
Storage of plasma al -30°C, with no prior treatment, resulted in significant (P<0.01) reductions in the biological and immunological activities of oxytocin after 10 days and further reductions after 20 days. Acidification with 0.1 N hydrochloric acid, or snap-freezing in solid carbon dioxide-acetone, before storage afforded some protection against these losses and a combination of both treatments preserved the biological and immunological activities for 20 days despite thawing and refreezing after 10 days.