Study on a New Open Tubular Capillary Liquid Chromatography(OTCLC) System Based on Micro-Phase Separation of Mixed Solvents

建议的开管毛细管液相色谱（OTCLC）系统利用最近发现的“微观不均匀性”在一些有机-水混合溶剂和盐析相分离现象，在这些混合溶剂中观察到。例如，乙腈与水以任何比例混溶;然而，在其水混合物中在分子水平上观察到了不均匀性。当合适盐浓度的乙腈-水混合物被泵入这样的毛细管时，微相分离可能发生在毛细管壁附近，在附着于毛细管内壁的富含水的水相中。换句话说，在毛细管的内壁上动态地形成具有与移动的相显著不同的性质的液膜。当分析物的混合物被注入毛细管中时，分析物的参与发生在移动的相与液膜之间，提供了所提出的色谱系统的分离能力。色谱仪清楚地证明了将中性化合物与带电化合物分离的能力。通过OTCLC系统。此外，还可以分离分子结构相似但电荷不同的化合物。洗脱顺序可以很容易地通过保留机制来解释。对硝基苯胺被有效地萃取到上层（乙腈富集）相中，而2，7-NDS保留在下层（水富集）相中，证实了观察到的洗脱顺序。移动的相中高浓度的乙腈含量略微增加了1-萘酚的洗脱时间，但显著增加了2，6-萘二磺酸的洗脱时间。更有趣的是，在不存在NaCl的情况下，在两种情况下（AN/aq 9/1和AN/aq 8/2）都没有观察到分离，证明了在毛细管中用于微相分离的额外电解质的必要性。

The proposed open tubular capillary liquid chromatography(OTCLC) system utilizes the recent discoveries of "microheterogeneity" in some organic-water mixed solvents and salting-out phase separation phenomena observed in these mixed solvents. For example, acetonitrile is miscible with water at any ratio ; heterogeneities, however, have been observed at a molecular level in its water mixtures. When an acetonitrile-water mixture of suitable salt concentration is pumped into such a capillary micro-phase separation is likely happening in the vicinity of the capillary wall, in a water-enriched aqueous phase attached to the capillary inner wall. In other words, a liquid membrane that has considerably different properties from the mobile phase is dynamically formed on the inner wall of the capillary.When a mixture of analytes is injected into the capillary, participation of the analytes occurs between the mobile phase and the liquid membrane, providing the separation power of the proposed chromatograpy system.Chromatographs clearly demonstrated the ability of separating neutral compounds from charged compounds by the OTCLC system. Moreover, it was also possible to separate compounds of similar molecular structure but different charges. The elution orders can readily be explained by the retention mechanism. p-Nitroaniline is effectively extracted to the upper (acetonitrile-enriched) phase while 2,7-NDS remains in the lower (water-enriched) phase, confirming the elution order observed. The high concentration of acetonitrile content in the mobile phase slightly increased the elution time of 1-naphthol but significantly increased the elution time of 2,6-naphtalene disulfonic acid. More interestingly, at the absence of NaCl, no separation in both cases (AN/aq 9/1 and AN/aq 8/2) were observed, demonstrating the necessity of additional electrolyte for the micro-phase separation in the capillary tubing.