The carbon dioxide/bicarbonate system is routinely used as a buffer in mammalian cell culture medium. However, due to the continuous degassing of carbon dioxide and its dependence on temperature, it is difficult to achieve the target pH during preparation at ambient temperature and without control of dissolved carbon dioxide, and even more so at cell culture operating conditions. These problems were amplified when preparing multiple (e.g., 20) customized preparations of an in-sourced proprietary medium during research and process development of mammalian cell culture systems. Thus, a mathematical model was created to specify the amount of acid or base to add during preparation so as to achieve the target pH of each medium at process conditions without having to do titration. The relationship between gaseous carbon dioxide and the dissolved carbon dioxide in the proprietary medium containing unknown species was specified using a modified Henry's law equation (as done in prior work). Further, to allow medium preparation without doing titration, the acid/base properties of the proprietary medium were fitted by a parameter related to its Net Medium Acids during specification of model parameters. A subset of the solutions was prepared and tested in bioreactors with controlled CO₂ flow to validate the model. Then, the model was used to assess the equivalence of the pHs of the customized medium formulations despite variations in pCO₂ that occurred during incubation and sampling.

中文翻译：

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用于指定碳酸氢盐缓冲细胞培养基配方 pH 值的半经验数学模型

二氧化碳/碳酸氢盐系统通常用作哺乳动物细胞培养基中的缓冲液。然而，由于二氧化碳的持续脱气及其对温度的依赖性，在环境温度下且不控制溶解的二氧化碳的情况下，制备过程中难以达到目标pH值，在细胞培养操作条件下更是如此。在哺乳动物细胞培养系统的研究和工艺开发过程中，当制备多种（例如，20）种内源专有培养基的定制制剂时，这些问题被放大。因此，创建了一个数学模型来指定在制备过程中添加的酸或碱的量，以便在工艺条件下达到每种介质的目标 pH 值，而无需进行滴定。气态二氧化碳与含有未知物质的专有介质中溶解的二氧化碳之间的关系是使用修改后的亨利定律方程指定的（如先前工作中所做的那样）。此外，为了允许在不进行滴定的情况下制备培养基，专有培养基的酸/碱特性在模型参数规范期间通过与其净培养基酸相关的参数进行拟合。在控制 CO 的生物反应器中制备和测试了一部分溶液 在指定模型参数期间，专有介质的酸/碱特性通过与其净介质酸相关的参数进行拟合。在控制 CO 的生物反应器中制备和测试了一部分溶液 在指定模型参数期间，专有介质的酸/碱特性通过与其净介质酸相关的参数进行拟合。在控制 CO 的生物反应器中制备和测试了一部分溶液₂流程验证模型。然后，该模型用于评估定制培养基配方的 pH 等效性，尽管在孵育和采样期间pCO ₂会发生变化。