逆向法测定酮洛芬对映体在Chiralpak AD柱上的吸附等温线

Determination of adsorption isotherms of ketoprofen enantiomers on Chiralpak AD column by inverse method

模拟移动床(SMB)色谱分离与纯化的操作过程复杂,对其进行设计与优化需要使用数值模拟方法,准确测定竞争型吸附等温线具有重要意义。采用逆向法确定了25℃下酮洛芬对映体在直链淀粉手性固定相(Chiralpak AD)上的竞争吸附等温线,先用高效液相色谱测得酮洛芬对映体在Chiralpak AD柱上的过载流出曲线,再通过拟合实验测得的流出曲线确定吸附等温线模型及其参数。研究中采用平衡扩散模型描述酮洛芬对映体在色谱柱上流出的瞬态过程。参数拟合过程中,首先用非支配基因算法(NSGA-Ⅱ)在较广的参数空间内搜索吸附等温线模型参数,再以所得结果作为初值,使用Levenberg-Marquardt算法(LMA)对参数进一步优化。比较了4种不同竞争吸附等温线模型对实验测得的流出曲线的拟合结果,其中五参数的Bi-Langmuir模型拟合程度最好。测量了不同进料浓度和进料量条件下的流出曲线,并通过与模型预测结果的对照验证了所确定吸附等温线模型和参数。

The determination of competitive adsorption isotherm is of great importance for model-based design and optimization of chromatographic separation processes,especially for the simulated moving bed due to its intrinsic complexity.The competitive adsorption isotherms of ketoprofen enantiomers on an amylose-based chiral stationary phase（Chiralpak AD）at 25℃ were determined in this study by the application of the inverse method.Elution profiles of various racemic feed signals were measured on a preparative chromatography column with a precise temperature control system.The parameters of isotherm models were determined by fitting the experimental elution profiles.The mass balance for component in the column was described by equilibrium-dispersive model.In the fitting procedure,isotherm parameters were searched over a wide range in the parametric space with the non-dominated sorting genetic algorithm（NSGA-Ⅱ）and polished with the Levenberg-Marquardt algorithm.Four competitive adsorption isotherm models were compared based on the fitting to the experimental data.Bi-Langmuir model with 5 parameters gave the best results.In order to validate this model and the model parameters,independent overloaded profiles with different concentrations and amount of feed were measured and compared with the model.Quantitatively good agreement was observed.