The use of ionic liquids in capillary electrophoresis, either as coating material or as components of the background electrolyte needs systematic standardization to set up optimal conditions. Excellent separation of the proteins was achieved using 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([emim][BF₄]) or 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim][BF₄]) ionic liquids using the properly made ionic‐liquid–water binary mixtures for the experiments. The binary mixture has a distinctly stable and well perceptible low pH, which depends on the concentration of the ionic liquid, and on the preparation time of the mixture. Optimal conditions for the electrophoretic separation were obtained upon a multivariate analysis of the experimental parameters (applied voltage, migration time, concentration, and type of the ionic liquid). The standardized condition provides a low electroendosmotic flow toward the anode, which, however, did not hinder the proteins to migrate toward the cathode. The migration of cytochrome c, lysozyme, myoglobin, trypsin, and apo‐transferrin at a pH around 2, far below the isoelectric points of the proteins, showed RSD values of the migration times less than 7.5% and less than 6.5% when using [emim][BF₄] or [bmim][BF₄], respectively, either in run‐to‐run or day‐to‐day experiments. The determination of the extent of the EOF is not possible with the commonly used EOF markers, due to interaction with the ionic‐liquid constituents. The interaction of the ionic liquids with the proteins influences the migration order in zone electrophoresis. This method has been applied successfully for the analyses of real biological samples such as proteins from egg whites and human tears.

中文翻译：

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使用离子液体进行动态包被和作为背景电解质成分的蛋白质的毛细管区带电泳

在毛细管电泳中使用离子液体，无论是作为涂层材料还是作为背景电解质的成分，都需要系统地进行标准化，以建立最佳条件。使用1-乙基-3-甲基咪唑四氟硼酸盐（[emim] [BF ₄ ]）或1-丁基-3-甲基咪唑四氟硼酸盐（[bmim] [BF ₄]）离子液体，使用适当制备的离子-液体-水二元混合物进行实验。二元混合物具有明显稳定且易于感知的低pH，这取决于离子液体的浓度以及混合物的制备时间。电泳分离的最佳条件是通过对实验参数（施加电压，迁移时间，浓度和离子液体类型）进行多变量分析获得的。标准化条件提供了低的向阳极的内电渗流，但是，这并不妨碍蛋白质向阴极迁移。细胞色素c，溶菌酶，肌红蛋白，胰蛋白酶和脱辅基转铁蛋白的迁移在pH值约为2时，远低于蛋白质的等电点，显示迁移时间的RSD值小于7.5％且小于6。[ ₄ ]或[bmim] [BF ₄ ]，分别在逐个实验或日常实验中进行。由于与离子液体成分的相互作用，使用常用的EOF标记无法确定EOF的程度。离子液体与蛋白质的相互作用影响区域电泳中的迁移顺序。该方法已成功地用于分析真实的生物样品，例如蛋清和人眼中的蛋白质。