Biologic activity of human chorionic gonadotropin following reversed-phase high-performance liquid chromatography

Human chorionic gonadotropin (hCG) was analyzed by reversed-phase high-performance liquid chromatography (HPLC) using mobile phases previously described in the literature, as well as newly developed solvent systems. Fractions of hCG collected following reversed-phase HPLC were bioassayed by activation of adenylate cyclase to determine their biologic potencies. hCG retained only 10-60% of its biologic activity following reversed-phase HPLC, depending on the chromatographic conditions employed. A portion of the reduced biologic activity was attributed to dissociation of the alpha- and beta-subunits of hCG at the low pH of the mobile phases, since neutralization of the pH prior to lyophilization and bioassay increased the biologic potency of the chromatographed hormone. The remaining loss in biologic activity is presumably due to organic solvent denaturation.