Tan Ting, Zhang Mingliang, Wan Yiqun, Qiu Hongdeng
State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China; Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Talanta. 2016;149:85-90. doi: 10.1016/j.talanta.2015.11.041. Epub 2015 Nov 17.
Deep eutectic solvents (DESs) were used as novel mobile phase additives to improve chromatographic separation of four quaternary alkaloids including coptisine chloride, sanguinarine, berberine chloride and chelerythrine on a C18 column. DESs as a new class of ionic liquids are renewably sourced, environmentally benign, low cost and easy to prepare. Seven DESs were obtained by mixing different hydrogen acceptors and hydrogen-bond donors. The effects of organic solvents, the concentration of DESs, the types of DESs and the pH values of the buffer solution on the separation of the analytes were investigated. The composition of acetonitrile and 1.0% deep eutectic solvents aqueous solution (pH 3.3, adjusted with hydrochloric acid) in a 32:68 (v/v) ratio was used as optimized mobile phase, with which four quaternary alkaloids were well separated. When a small amount of DESs was added in the mobile phase for the separation of alkaloids on the C18 column, noticeable improvements were distinctly observed such as decreasing peak tailing and improving resolution. The separation mechanism mediated by DESs as mobile phase additives can be attributed to combined effect of both hydrogen acceptors and hydrogen-bond donors. For example, choline chloride can effectively cover the residual silanols on silica surface and ethylene glycol can reduce the retention time of analytes. The proposed method has been applied to determine BerbC in Lanqin Chinese herbal oral solution and BerbC tablet. Utilization of DESs in mobile phase can efficiently improve separation and selectivity of analytes from complex samples.
深共熔溶剂（DESs）被用作新型流动相添加剂，以改善在C18柱上对包括氯化黄连碱、血根碱、氯化小檗碱和白屈菜红碱在内的四种季铵生物碱的色谱分离。DESs作为一类新型离子液体，可再生、环境友好、成本低且易于制备。通过混合不同的氢受体和氢键供体获得了七种DESs。研究了有机溶剂、DESs浓度、DESs类型和缓冲溶液pH值对分析物分离的影响。以体积比32:68的乙腈和1.0%深共熔溶剂水溶液（用盐酸调节pH至3.3）的组合物作为优化的流动相，四种季铵生物碱得以良好分离。当在流动相中加入少量DESs用于在C18柱上分离生物碱时，明显观察到了显著的改善，如峰拖尾减少和分离度提高。DESs作为流动相添加剂介导的分离机制可归因于氢受体和氢键供体的联合作用。例如，氯化胆碱可有效覆盖硅胶表面的残留硅醇，乙二醇可缩短分析物的保留时间。所提出的方法已应用于测定蓝芩中药口服液和小檗碱片中的小檗碱含量。在流动相中使用DESs可有效提高复杂样品中分析物的分离度和选择性。
