离子交换色谱中混合保留机理的研究

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吸附作用, 选择阴离子交换色谱柱IonPacAS9-HC为研究对象, 针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. 在五根不同批号IonPacAS9-HC (250 mm×2 mm I.D.)柱上, 以含50%乙腈(V/V)的9 mmol/L Na₂CO₃为流动相, 0.25 mL/min流速, 对12个不同结构类型的无机和有机阴离子(氟离子、氯离子、硫酸根、磷酸根、二羟基丁酸、丙酮酸、乙酸、丙烯酸、苯甲酸、丙二酸、酒石酸和邻苯二甲酸)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, 为离子交换色谱中吸附保留行为的研究提供了新方法.

Mixed-Mode Retention Mechanism of Ion Exchange Chromatography

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. Experimental retention data were obtained on five Dionex IonPac AS9-HC columns using a 9 mmol/L Na₂CO₃ solution containing 50% (V/V) acetonitrile as eluent. The calculations of twelve anions (fluoride, chloride, sulfate, phosphate, dihydroxybutyric acid, pyruvic acid, acetic acid, acrylic acid, benzoic acid, malonic acid, tartaric 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 and 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.