摘要
以ＰＥＧ２０Ｍ为代表研究了石英毛细管柱气液色谱保留过程，提出了利用毛细管柱测定分配和吸附常数的公式，并测定了９个温度下的分配和吸附常数。计算了８０℃和１２０℃下４支不同液膜厚度柱上吸附对保留的贡献。结果表明，在薄液膜的柱子上界面吸附对保留具有重要贡献；温度升高可以降低弱极性化合物（如正构烷烃和饱和醚）吸附对保留的贡献，但对其它化合物影响不明显。验证了正构烷烃、２－酮系列和正构伯醇的吸附常数的碳数规律。由于溶质从界面向体相转移对能量并不是一个很有利的过程，因而产生了有意义的界面吸附；吸附的强弱与溶质的沸点和溶质在体相的作用大小有关，在此基础上得出了吸附常数与分配常数和沸点的关系。通过吸附和分配常数与温度的关系内插或外推计算各化合物在相应沸点时的平衡常数，结果表明二者间仅相差一个常数。
Fused silica capillary column was used to examine the mechanism by which solutes are retained in gas liquid chromatography so as to eliminate the disturbance from support used in packed column. An equation was derived to correlate capacity factor with equilibrium constants in process of partition between gas liquid phases (K L) and adsorption on gas liquid interface (K GL ) and parameters of column from original equation by Martin in packed column. In this work PEG 20M was used to prepare columns with different thickness of liquid film and on these columns the capacity factors of 29 solutes belonging to various classes were determined at nine temperatures. The obvious interfacial adsorption was observed especially when low phase loading column and low column temperature used. To examine the characteristics of interfacial adsorption the correlation of lnK GL with carbon number for three homologous series and with temperature were achieved. Authors found that the enthalpy in interfacial adsorption is higher than that in partition, especially for n alkanes and lnK GL can be linearly correlated with boiling point and lnK L. Consequently, authors believe that the molecular interaction on gas liquid interface is a mixed one from solute solvent and solute solute. Therefore, interfacial adsorption cannot be significantly decreased through the increase of column temperature when solute solvent interaction is similar to solute solute one. The data of lnK GL and lnK L at the boiling point of solute given by interpolation or extrapolation showed that the difference of them have nothing to do with the properties of solute.
出处
《色谱》
CAS
CSCD
北大核心
1998年第1期6-12,共7页
Chinese Journal of Chromatography
关键词
毛细管
气液相色谱
保留过程
气液界面吸附
GLC
capillary gas liquid chromatography, retention process, interfacial adsorption
