A radio-immunoelectrophoretic assay for human growth hormone

although it was unretarded on Sephadex G-200. It did not react with antiserum raised against standard growth hormone. Growth-hormone preparations (peak II) obtained from such Sephadex columns have not been used as standards in the present assay but have been used in the preparation of 1311-labelled growth hormone. In an experi- ment carried out in conjunction with Dr H. E. C. Cargill Thompson (Clinical Endocrinology Research Unit, Edin- burgh), peak I and peak II materials were assayed in terms of the starting material by the radio-immunoassay and by the tibia-line bioassay. Peak I was immunologically 18-4% and biologically 19-7% (fiducial limits 13-30%) of the starting material. Peak II was immunologically 120 % and biologically 142% (fiducial limits 111-228%) of the starting material.