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离子交换色谱保留机理的研究
Studies on the Retention Mechanism of Ion Exchange Chromatography
【作者】 张嘉捷；
【导师】 朱岩；
【作者基本信息】 浙江大学 ， 分析化学， 2008， 博士
【摘要】 本论文在综述了离子交换色谱的分离体系以及传统色谱理论的基础上,研究了离子交换色谱保留机理,论文主要分为以下三个方面:一、鉴于离子交换色谱中被测离子和有机聚合物树脂之间存在的疏水作用,以阴离子交换色谱柱IonPacAS9-HC为研究对象,对离子交换色谱中的吸附保留行为,从色谱混合保留机理的角度出发,考虑各色谱柱固定相含量和界面吸附面积的不同,建立柱间保留的相互关系方程:V’R（X）/V’R（S2）=aV’R（S1）/V’R（S2）+b。在5根不同批号IonPacAS9-HC柱上,对15个不同结构类型的无机和有机阴离子的保留行为进行研究,并采用推导所得的混合保留机理模型对溶质这一保留特征进行表征,结果较为理想,其中一价离子的相关系数为0.9～0.999,二价离子的相关系数为0.999～1;对保留值进行预测也得到较为准确的结果,为离子交换色谱中吸附保留行为的研究提供了新方法。二、测定了IonPacAS9-HC阴离子交换色谱柱在293、303、313、318、323K柱温下35个无机和有机阴离子的保留值,考察了柱温对色谱保留的影响,同时求得各溶质色谱过程中的热力学焓变（△H）和似交换熵变（△S’）,从热力学角度对离子交换色谱保留机理进行解释,发现在离子色谱中类似于碳数规律的实验现象;提出用静电作用、色散作用和氢键作用为离子交换色谱中保留作用的主要形式,采用Gaussian98W对所测的化合物进行HF/6-31*水平上的优化,并提取21种结构参数来描述这三种作用力,研究了△H和AS’与结构参数间的关系,从结构参数出发进一步对保留机理进行分析,首次建立了24个羧酸结构参数和热力学参数的定量关系（QSPR）。三、在上述工作的基础上,将计算得到的结构参数作为理论描述符引入到与离子色谱容量因子的多元线性回归中,建立25个羧酸在不同柱温下的色谱定量保留关系（QSRR）模型,通过比较这些模型,对离子交换色谱保留机理进行进一步的讨论。
【Abstract】 My study on the retention mechanism of ion exchange chromatography includes following parts:1.Because of hydrophobic interaction between the sample ions and the polymer matrix of ion exchanger,it has been shown that a mixed-mode mechanism of ion exchange and adsorption interaction occurs in ion exchange chromatography.In consideration of the difference of exchange capacity and adsorption area,an equation for interrelation among retention values of the columns was derived as follows:V’R（X）/V’R（S2）=a·V’R（S1）/V’R（S2）+b,where a and b are expressed by distribution coefficient and adsorption coefficient of predicted ion（x）,benzoic acid or o-phthalic acid（S1）and toluene（S2）.The calculations of fifteen anions （fluoride,chloride,nitrate,sulfate,phosphate,dihydroxybutyric acid,pyruvic acid,acetic acid,acrylic acid,salicylate,benzoic acid,malonic acid,tartaric acid, oxalic acid and o-phthalic acid）on five Dionex IonPac AS9-HC columns in accordance with the developed method have shown the good precision of the above equation.The correlation coefficients calculated for monovalent anions were between 0.9～0.999 and for divalent were between 0.999 and 1.This work can offer a new method for studies on adsorption interaction of ion exchanger.2.The effect of oven temperature（293,303,313,318,323K）on separation parameters of a chromatographic system of IonPacAS9-HC column and 9 mmol/L Na2CO3（containing 50%acenitrile）was studied.Thermodynamic constants△H and△S’ were calculated.Based on these values,the retention mechanism of solute ions with different structure was discussed and the relationships between thermodynamic functions and molecular structures were evaluated.21 structure parameters that were calculated by HF/6-31* level were chosen based on the hypothesis that there were three kinds of intermolecular force including electrostatic interaction,hydrogen bond force and dispersion force in the process of ion-exchange chromatography.The models of quantitative structurethermodynamic constants relationship,which were established through stepwise regression techniques,were used to interpret the chromatographic retention mechanism.3.According to the structural properties of 25 carboxylic acids that were fully computed at HF/6-31* level in the above chapter,several structure-retention relationships（QSRR）under the different oven temperatures by using the method of multiple linear regression have been developed.Comparing these models,the main factors affecting the retention time of carboxylic acid were investigated.As a result,the chromatographic retention mechanism was discussed.