Separation of Somatropin and Its Degradation Products by High-Performance Liquid Chromatography Using a Reversed-Phase Polymeric Column

The accurate prediction of protein stability is one of the most challenging goals in protein formulation and delivery. In this study, a gradient RP-HPLC method is described for the separation of human growth hormone (hGH) variants as deamidated and oxidized forms. The methodology employed a polymeric poly (styrene-co-divinylbenzene) column and a 1mL/min flow rate of a linear gradient of 0.1% v/v TFA/acetonitrile and TFA/Water (pH=2.0) mixture as the mobile phase. The overall run time of this method was 12 min and the average retention times were about 8.7 min for the native somatropin, 7.2 min for the deamidated form and 1.6 and 5.3 min for oxidized variants. The method was also validated in terms of selectivity, linearity, intraand inter-day variations. In conclusion the method was found to have the potential for being applied as an initial and rapid evaluation method for assessing the quality and quantity of hGH during downstream processing, formulation and storage.