(75b) Characterizing the Formation of Inverse Solubility Salt Precipitates in Cell Culture Media and Mitigation Strategies During Thermal Treatment for Viral Inactivation

In mammalian cell culture production processes it is essential to maintain a sterile envelop around the bioreactor system against adventitious agents. Heat treatment methods for inactivating viruses in cell culture media have been widely adopted in the biotechnology industry. The presence of salts of inverse solubility in media presents a precipitation challenge during heat inactivation. In this study we characterized the formation of inverse solubility phosphate salts during heating by differential scanning calorimetry (DSC) and the real time, physical behavior of the particles using focused beam reflectance measurements (FBRM) and particle vision microscopy (PVM). We also identified a temperature zone of 85 - 90°C where the onset of precipitation occurs. We also defined low pH conditions of ≤ 6.65 which suppress the formation of phosphate salts in chemically defined platform media. Removal of cationic or anionic species of the precipitating salts in media has also been demonstrated to be effective tools in mitigating precipitation.