STUDY OF PREPARATIVE REVERSED-PHASE CHROMATOGRAPHY BY APPLICATION OF KINETIC AND EQUILIBRIUM-MODELS OF COLUMN OVERLOAD
STUDY OF PREPARATIVE REVERSED-PHASE CHROMATOGRAPHY BY APPLICATION OF KINETIC AND EQUILIBRIUM-MODELS OF COLUMN OVERLOAD
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DOI：
10.1016/s0021-9673(01)88962-7
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发表时间：
1989-12-22
期刊：
影响因子：
--
通讯作者：
CARR, PW
中科院分区：
文献类型：
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作者：
LUCY, CA;WADE, JL;CARR, PW
目前，有三种基本的色谱柱过载模型，它们导致峰形的封闭形式方程。所有这些都使用一些简化的假设，使数学易于处理，同时保留了非线性色谱行为的重要特征。本文采用基于托马斯工作的动力学模型和霍顿和Haarhoff-Van der Linde的平衡模型研究反相色谱中的过载过程。通过调整参数，三种模型在中等过载（最高达柱容量的2.5%）条件下都能与实验峰形接近，但对于较高的过载，Haarhoff-Van der Linde模型不能再现实验峰形。所有的模型都涉及一组三个物理化学参数。这些参数与稀释条件下的保留（容量因子，k“）和峰宽以及等温线过载程度有关。实验结果表明，只有与k“有关的参数基本上与溶质浓度和流量无关。原则上，对于所有三种模型的峰宽参数应该是独立的溶质浓度，但在所有情况下，这个参数被发现变化，使固有的峰宽随浓度增加。考虑到所有三种模型都显示出相同的趋势，即使在我们认为数学近似合理的适度低过载下，我们认为峰宽参数的变化显示出一种未知的额外谱带增宽现象，该现象与过载程度有关，与流速无关。溶质的负载能力，在吸附位点密度方面，可以从等温线过载参数计算。所有三种模型的容量都与流速无关，但只有动力学模型的容量与上样量无关。来自动力学模型的吸附位点密度的一些不同的移动的相和溶质是一致的结果，从更传统的等温线研究。对于化学上简单的溶质如苄基链烷醇，获得约3-4 μ mol/m2的位点密度。
Currently, there are three fundamental models of column overload which lead to closed-form equations for the peak profile. All use some simplifying assumption(s) to make the mathematics tractable, while at the same time retaining important features of the non-linear chromatographic behavior. In this work, the kinetic model based on the work of Thomas and the equilibrium models of Houghton, and Haarhoff-Van der Linde are used to study overload processes in reversed-phase chromatography. By adjustment of the parameters, all three models can be made to closely match the experimental peak shapes under conditions of moderate overload (up to 2.5% of the column capacity) but for higher overloads the Haarhoff-Van der Linde model fails to reprouce the experimental peak shape. All of the models involve a set of three physico-chemical parameters. These parameters are related to retention (capacity factor, k'') and peak width under dilute conditions, and to the degree of isotherm overload. Experimental results show that only the parameter related to k'' is essentially independent of the solute concentration and flow-rate. In principle, for all three models the peak width parameter should be independent of solute concentration, but in all cases this parameter was found to vary such that the intrinsic peak width increased with concentration. Given that all three models display this same trend, even at moderately low overloads where we feel the mathematical approximations are reasonable, we believe that the change in the peak width parameters shows an as yet unknown additional band broadening phenomenon which is related to the degree of overload and independent of flow-rate. The solute loading capacity, in terms of the adsorption site density, can be calculated from the isotherm overload parameter. The capacity is independent of flow-rate for all three models, but only that from the kinetic model is also independent of the amount of sample loaded onto the column. The adsorption site density derived from the kinetic model for a number of different mobile phases and solutes is consistent with results from more traditional isotherm studies. For chemically simple solutes such as the benzyl alkanols, a site density of about 3-4 .mu.mol/m2 was obtained.