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Elution-extrusion countercurrent chromatography. Use of the liquid nature of the stationary phase to extend the hydrophobicity window

机译:洗脱-挤出逆流色谱法。利用固定相的液体性质扩展疏水性窗口

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Countercurrent chromatography (CCC) is a liquid chromatography technique with a liquid stationary phase. Taking advantage of the liquid nature of the stationary phase, it is possible to perform unique operations not possible in classical liquid chromatography with a solid stationary phase. It is easy to avoid any solute-irreversible absorption in the CCC column. If the retention volumes of solutes become too high, the dual mode will be used. The roles of the phases are reversed. The stationary phase becomes the mobile phase, and the CCC column is started again. The solutes elute rapidly in what was previously the stationary phase. The theoretical basis of the dualmode method is recalled. The dual-mode method is a discontinuous method. The separation should be stopped when the phase switch is performed. The elution-extrusion procedure is another way to avoid any irreversible adsorption of solutes in the column. The method uses the fact that the liquid volumes occupied by the solutes highly retained inside the column can be orders of magnitude lower than the mobile-phase volume that would be needed to elute them. The elution-extrusion method also has two steps: the first step is a regular CCC chromatogram. Next, the stationary phase containing the partially separated hydrophobic solutes is extruded out of the column in a continuous way using the liquid stationary phase. The theory of the process is developed and compared to the dual-mode theory. Alkylbenzene homologues are experimentally used as model compounds with the heptane/methanol/water biphasic liquid system to establish the theoretical treatment and compare the performance of two types, hydrodynamic and hydrostatic, of CCC columns. It is shown that the method can dramatically boost the separation power of the CCC technique. An apparent efficiency higher than 20 000 plates was obtained for extruded octylbenzene and a 160-mL hydrodynamic CCC column with less than 500 plates when conventionally used. [References: 28]
机译:逆流色谱法(CCC)是具有液相固定相的液相色谱技术。利用固定相的液体性质,可以执行传统的液相色谱法(具有固体固定相)无法实现的独特操作。避免CCC色谱柱中任何不可逆的溶质吸收很容易。如果溶质的保留体积太高,将使用双重模式。这些阶段的作用相反。固定相变为流动相,CCC柱再次启动。溶质在以前的固定相中快速洗脱。回顾了双模方法的理论基础。双模式方法是不连续的方法。进行相位切换时,应停止分离。洗脱-洗脱程序是避免色谱柱中任何不可逆吸附的溶质的另一种方法。该方法利用以下事实:高度保留在色谱柱内部的溶质所占的液体体积可能比洗脱它们所需的流动相体积低几个数量级。洗脱-挤出方法还包括两个步骤:第一步是常规CCC色谱图。接下来,使用液体固定相以连续的方式将含有部分分离的疏水性溶质的固定相从柱中挤出。该过程的理论得到发展,并与双模理论进行了比较。烷基苯同系物在庚烷/甲醇/水双相液体系统中用作模型化合物,以建立理论处理并比较CCC色谱柱的两种类型(流体动力和流体静力)的性能。结果表明,该方法可以大大提高CCC技术的分离能力。常规使用挤出的辛基苯和160-mL流体动力学CCC色谱柱时,表观效率高于20000板。 [参考:28]

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