Radioimmunoassay of morphine and morphine-like substances in biological fluids and human tissues.

A radioimmunoassay is described for the determination of morphine and morphine-like substances in plasma, serum, biological fluids and tissue homogenates using an antiserum to morphine-6-hemisuccinyl-BSA and 125I-morphine as the labelled tracer. In the B/F separation with ammonium sulphate, calcium sulphate was added to make the precipitate more compact. Some parameters related to the use of this method in direct assay on plasma, serum, other biological fluids and tissue homogenates were evaluated.