Fluorometric assay of vasopressin and oxytocin: a general approach to the assay of peptides in tissues.

Abstract
A fluorometric method for the quantitative assay of vasopressin and oxytocin in individual rat pituitaries was developed. Acid extracts of pituitaries are freed of amino acids and polyamines by passage over a copper-Sephadex column, and the peptide fraction is then labeled by reaction with fluorescamine. The resulting peptide fluorophors are separated by chromatography on a reverse-phase bonded column. Specificity of the procedure was ascertained by several criteria, including bioassay and amino-acid analysis of the eluted peptide fluorophors. The procedure serves as a model system for the assay of tissue peptides in the picomole range.