Ståhlberg J, Jönsson B, Horváth C
Astra Pharmaceutical Production AB, Quality Control, Södertälje, Sweden.
Anal Chem. 1992 Dec 15;64(24):3118-24. doi: 10.1021/ac00048a009.
We have recently proposed a theoretical framework for the effect of the eluting salt ionic strength of the eluent on the retention factor of proteins in ion-exchange chromatography of proteins. It is based on the solution of the linearized Poisson-Boltzmann equation for two oppositely charged planar surfaces in contact with a salt solution and describes the coulombic interaction between the protein and the oppositely charged stationary-phase surface. At sufficiently high salt concentrations in the mobile phase van der Waals interactions between the protein and the stationary phase become important. In this work we consider the effect of salt on the combined coulombic and van der Waals interactions by combining the electrostatic theory with the theory for van der Waals interactions. The combined theory describes the retention of proteins as a function of eluting salt concentration over a wide salt concentration range. The protein molecules are, according to the proposed theory, held in a diffuse layer close to the stationary phase and are not in a distinct layer, which is assumed in the traditional thermodynamic interpretation of the capacity factor. For this reason, we also examine the thermodynamic interpretation of the capacity factor when it is due to distant dependent interactions.
我们最近提出了一个理论框架，用于阐述洗脱液中洗脱盐的离子强度对蛋白质离子交换色谱中蛋白质保留因子的影响。该框架基于与盐溶液接触的两个带相反电荷的平面的线性化泊松 - 玻尔兹曼方程的解，描述了蛋白质与带相反电荷的固定相表面之间的库仑相互作用。在流动相中盐浓度足够高时，蛋白质与固定相之间的范德华相互作用变得重要。在这项工作中，我们通过将静电理论与范德华相互作用理论相结合，考虑盐对库仑相互作用和范德华相互作用综合作用的影响。该综合理论描述了在很宽的盐浓度范围内蛋白质保留率与洗脱盐浓度的函数关系。根据所提出的理论，蛋白质分子被保持在靠近固定相的扩散层中，而不是处于传统容量因子热力学解释中所假设的清晰层中。因此，我们还研究了容量因子由于远程依赖相互作用而产生时的热力学解释。
