Chang C A, Wu Q, Eastman M P
J Chromatogr. 1986 Dec 26;371:269-82. doi: 10.1016/s0021-9673(01)94711-9.
The capacity factors of several substituted anilines were measured on a beta-cyclodextrin (beta-CD)-bonded column with mobile phases varying from the classical, normal-phase condition, e.g. n-heptane-2-propanol, to the classical, reversed-phase condition, e.g. water-2-propanol. Different modifiers, such as acetonitrile, methanol, and tetrahydrofuran and a Partisil PXS-ODS column were also used for comparison. In general, it was found that the beta-CD column, having the ability to form inclusion complexes with certain substrates is better and more selective in the reversed-phase separation of many aromatic compounds than the Partisil PXS-ODS column. The normal-phase separation on beta-CD was even more efficient, owing to the presence of large number of hydroxy groups on the surface of beta-CD molecules and the more rapid mass transfer in the column. In the present case, alcohols were found to be better modifiers than aprotic solvents. The effects of organic solvents on both normal-and reversed-phase separations are also discussed. The minima observed for the log k' vs. percent organic solvent plots for a number of substituted anilines are reasoned to originate from solute-solvent competition, which interacts with the stationary phase, as well as from the "relative solubility" of solutes in the stationary and mobile phases.
在β-环糊精（β-CD）键合柱上测定了几种取代苯胺的容量因子，流动相从经典的正相条件（如正庚烷-2-丙醇）到经典的反相条件（如水-2-丙醇）不等。还使用了不同的改性剂，如乙腈、甲醇和四氢呋喃，并使用Partisil PXS-ODS柱进行比较。一般来说，发现能够与某些底物形成包合物的β-CD柱在许多芳香族化合物的反相分离中比Partisil PXS-ODS柱更好且更具选择性。由于β-CD分子表面存在大量羟基以及柱中传质更快，β-CD上的正相分离效率更高。在本实验中，发现醇类是比非质子溶剂更好的改性剂。还讨论了有机溶剂对正相和反相分离的影响。一些取代苯胺的log k'对有机溶剂百分比图中观察到的最小值被认为源于与固定相相互作用的溶质-溶剂竞争，以及溶质在固定相和流动相中的“相对溶解度”。
