Radioimmunoassay of estradiol-17beta in bovine peripheral plasma with and without chromatography

An assay of estradiol-17beta (E217beta) in bovine peripheral plasma is described. The plasma is incubated with an antiserum to E217beta-BSA and the gamma-globulin fraction precipitated with ammonium sulphate. After extraction with diethyl ether E217beta in the precipitate is estimated by radioimmunoassay using a specific antiserum against E217beta-6-BSA. Plasma concentrations of E217beta during the normal estrous cycle determined by this method and by a method involving Sephadex LH-20 chromatography range from 4 to 23 pg/ml.