A Kinetic Study on the Mass Transfer Phenomena in Reversed-Phase Liquid Chromatography

通过脉冲响应实验和反相液相色谱（RPLC）条件下的矩分析，对柱内传质现象进行了动力学研究。采用了各种具有不同物理化学性质的固定相，即与不同碳数烷基链键合的多孔硅胶颗粒，与不同表面覆盖率的C_<18>-配体键合的多孔硅胶颗粒，与苯基键合的多孔硅胶颗粒，由苯乙烯-二乙烯基苯共聚物制成的多孔硅胶颗粒，以及由石墨碳制成的多孔硅胶颗粒。流动相主要采用甲醇/水混合物，样品化合物主要采用苯衍生物和苯酚衍生物的标准物质。保留平衡和传质动力学信息由洗脱峰谱的第一个绝对矩和第二个中心矩得到。重点研究了其表面扩散的特征和机理。就笔者所知，目前还没有对表面扩散进行系统的研究。在不同温度条件下进行脉冲响应实验，得到了保留平衡和表面扩散的热力学性质。本文试图从多个角度对研究结果进行系统分析，以期对RPLC的分离机制有一个统一的认识。在表面扩散结果的基础上，提出了表面限制分子扩散模型作为表面扩散的一级近似。新模型是根据绝对速率理论建立的。该模型对于全面解释表面扩散的内在特征和机理是有效的。通过求解色谱一般速率模型的拉普拉斯域基本方程，导出了连续多孔分离介质填充整体柱的矩方程。他们将峰矩和表征整体柱中保留平衡和传质动力学的一些参数联系起来。通过对一组实验数据的应用，得到了C_<18>-硅整体柱传质动力学的一些新信息。验证了新矩方程的有效性。少

Kinetic studies on the mass transfer phenomena in columns were studied by means of pulse response experiments and the moment analysis under the conditions of reversed-phase liquid chromatography (RPLC). Various stationary phases having different physical and chemical properties were used, that is, porous silica gel particles bonded with alkyl chains of different carbon numbers, porous silica gel particles bonded with C_<18>-ligands of different surface coverages, porous silica gel particles bonded with phenyl group, porous particles made of styrene-divinylbenzene copolymer, and porous particles made of graphitic carbon. Methanol/water mixtures and standard materials of benzene derivatives and phenol derivatives were mainly used as the mobile phases and sample compounds, respectively. The information about the retention equilibrium and mass transfer kinetics were derived from the first absolute moment and the second central moment of the elution peak profiles. Especially, the characteri … More stics and mechanism of surface diffusion were studied in detail. To the best of the author's knowledge, there is so far no systematic study on surface diffusion. Thermodynamic properties of the retention equilibrium and surface diffusion were derived from the results of the pulse response experiments carried out under different temperature conditions. It was tried to systematically analyze the results in this study from various points of view in order to consistently understand the separation mechanism in RPLC.On the basis of the results about surface diffusion, the surface-restricted molecular diffusion model was proposed for surface diffusion as a first approximation. The new model was formulated according to the absolute rate theory. This model is effective for a comprehensive interpretation of the intrinsic characteristics and mechanism of surface diffusion.New moment equations were derived for monolithic columns packed with continuous porous separation media by solving the basic equations of the general rate model of chromatography in the Laplace domain. They correlate the peak moments and some parameters characterizing the retention equilibrium and the mass transfer kinetics in monolithic columns. Some items of new information on the mass transfer kinetics in C_<18>-silica monolithic columns were derived by applying the new moment equations to a set of experimental data. The validity of the new moment equations was confirmed. Less