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化学学报
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化学学报 ›› 1996, Vol. 54 ›› Issue (5): 497-503. 上一篇    下一篇

研究论文

反相高效液相色谱中溶质保留过程的热力学研究 Ⅱ. 焓变及其分量, 吸附及解吸附焓变

耿信笃   

  1. 西北大学现代分离科学研究所
  • 发布日期:1996-05-15

Studies on thermodynamics in solute retention of reversed-phase high performance liquid chromatography Ⅱ. Enthalpy change and its fractions, adsorption and desorption enthalpy changes

GENG XINDU   

  • Published:1996-05-15

PDF

368

被引次数

14 | 8

依据液相色谱中溶质计量置换保留模型, 从理论上分别推导出了在反相高效液相色谱(RP-HPLC)中lgI(与1mol溶质对固定相的亲合势有关的常数)和Z(对应于1mol溶质被固定相吸附时释放出置换剂的摩尔数)对绝对温度导数的线性关系式。发现非极性与极性小分子溶质的lgI和Z均具有热力学衡常数的特征。如在前报[1]报告的吉布斯自由能变一样, 也推导出了可将溶质保留过程中的总吸附焓变△H(Pa)分成两个独立的分量, 吸附焓变△(1,a)和解吸附焓变△H(Z,D)的表达式。可同时对在流动相中不同置换剂浓度条件下的△H(Pa)和△(Z,D)进行估算,并与实验值进行了比较, 偏差小于±10%。并用△H(1,a)和△H(Z,D)值对溶质在RP-HPLC的保留过程中热变化进行了解释。

关键词: 高速液体色谱, 吸附, 反相色谱, 焓, 解析, 热力学研究

Based on the stoichiometric displacement model for retention in liquid chromatography, two linear relations for the plots of lgI (constant relating to the affinity of 1mol solute to stationary phase) and Z (moles of displacing agent released as 1mol solute is adsorbed versus reciprocal of absolute temperature) in reversed-phase high preformance liquid chromatography (RP-HPLC) were theoretically derived, respectively. It was found that both lgI and Z of both apolar and polar small solutes have the characters of thermodynamical equilibrium constant. The total enthalpy during retention process of solute, as the same instance as that of Gibbs free energy reported in the previous paper, can also be divided into two independent fractions, adsorption and desorption enthalpy changes which can be used to evaluate both △H(Pa) and △H(Z,D) with various concentrations of displacing agent in mobile phase. With the comparisons between the experimental and the evaluated results, the standard deviation was found to be less than ±10%. The changes in heat during retention process in RP-HPLC were also explained with the magnitudes of the △H(1,a) and the △H(Z,D).

Key words: HIGH SPEED LIQUID CHROMATOGRAPHY, ADSORPTION, REVERSED PHASE CHROMATOGRAPHY, ENTHALPY, ANALYTIC

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