Preparation of Human Placental Lactogen (HPL) National Standard for Immunoassay

The raw material is analyzed for preparation of HPL national standard (NS) for im-munoassay. Impure zone is not found by polyacrylamide gel electrophoresis,protein amount is 1. 06 g/L and immunoactivity is 2.187 g/L by RIA.with its dose-response curve being parallel to that of HPL International Reference Preparation(IRP) coded (73/545). The results demonstrate that this material is suitable to be prepared as HPL NS. 2. 06 mL of raw material diluted in 0.01mol/L phosphate buffer (pH7. 4) containing 0. 2% human serum albumin and 1% mannitol is distributed into aliquot of 0. 5 mL (15μg per ampoule), lyophilized and assayed by RIA. The mean value of the NS is 14.19μg per ampoule in terms of IRP. Similar values are obtained for the HPL contents of quality control serum samples at different dose levels when ether the IS or NS is used as the assay calibrator. It indicats that there is no statistically significant difference between the serum sample values at the same levels.