Lebrón-Aguilar R, Quintanilla-López J E, Tello A M, Pérez-Parajón J M, Santiuste J M
Institute of Physical Chemistry Rocasolano, Department of Molecular Structure and Dynamics, Madrid, Spain.
J Chromatogr A. 2005 Dec 30;1100(2):208-17. doi: 10.1016/j.chroma.2005.09.044. Epub 2005 Oct 19.
The method of solvation model has been applied to five poly (methyl-trifluoropropyl) siloxanes (TFPSXX) prepared in our laboratories, at five trifluoropropyl (TFP) group contents, XX = 0, 11.5, 26.3, 35.5 and 50.0%, at 80, 100, 120 and 140 degrees C. Previously, specific retention volumes of 60-odd solutes of varied polarities were measured upon each of these stationary phases within the above temperature range. Constant s prevails over all other constants, TFPSXX stationary phases showing strong dipole/induced dipole forces with the solutes, moderate acidity and no basicity at all. Constant e is zero in the stationary phase without TFP groups, but has negative low-medium values for the other fluorine contents, XX from 11.5 to 50.0%, hinting at repulsive forces, as expected. Normal values for constant l, decreasing from the less cohesive TFPS00 to the more cohesive TFPS50, were found. For each TFP content constants s, a and l show a negative temperature dependence, while constant e increases as temperature increases. Constant c also decreases with increasing temperature. At each temperature, constants s and a increase with increasing %TFP (or increasing stationary phase polarity), whereas constants e and l show the opposite trend, diminishing with increasing polarity of the stationary phase. Principal component analysis shows that the five stationary phases presented in this work conform a group with other earlier synthesized trifluoropropyl siloxanes and other fluorinated stationary phases taken from literature: VB-210, QF-1, DB-200, DB-210 and PFS6, showing the same selectivity which only the fluorine atom confers. A dendrogram of 38 stationary phases supports these results.
溶剂化模型方法已应用于我们实验室制备的五种聚（甲基 - 三氟丙基）硅氧烷（TFPSXX），其具有五种三氟丙基（TFP）基团含量，XX = 0、11.5、26.3、35.5和50.0%，温度为80、100、120和140摄氏度。此前，在上述温度范围内，已测量了这些固定相上60多种不同极性溶质的比保留体积。常数s在所有其他常数中占主导地位，TFPSXX固定相对溶质表现出强偶极/诱导偶极力，酸度适中且完全没有碱性。在没有TFP基团的固定相中，常数e为零，但对于其他氟含量（XX从11.5%到50.0%），具有负的中低值，正如预期的那样暗示了排斥力。发现常数l的正常值，从内聚性较小的TFPS00到内聚性较大的TFPS50逐渐减小。对于每种TFP含量，常数s、a和l表现出负的温度依赖性，而常数e随温度升高而增加。常数c也随温度升高而降低。在每个温度下，常数s和a随TFP%增加（或固定相极性增加）而增加，而常数e和l则呈现相反的趋势，随固定相极性增加而减小。主成分分析表明，本工作中呈现的五个固定相与其他早期合成的三氟丙基硅氧烷以及文献中获取的其他氟化固定相：VB - 210、QF - 1、DB - 200、DB - 210和PFS6形成一组，显示出仅由氟原子赋予的相同选择性。38个固定相的树形图支持了这些结果。
