Department of Analytical Chemistry, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Kraków, Poland.
Molecules. 2022 Aug 6;27(15):5010. doi: 10.3390/molecules27155010.
This article presents the first successful application of a capillary electrophoresis-microscale thermophoresis tandem technique (CE-MST) for determining the values of equilibrium constant, realized by connecting online the CE and MST instruments using a fused-silica capillary. The acid-base dissociation of fluorescein isothiocyanate, expressed by the acidity constant value (p), was used as a model. The measurement procedure consisted of introducing a mixture containing the analyte and a deliberately added interferent into the CE capillary, electrophoretic separation of the analyte from the interferent, the detection of the analyte with a CE-integrated detector, detection with a MST detector, and then stopping the flow temporarily by turning off the voltage source to conduct the thermophoretic measurement. The analysis of migration times, peak areas and MST responses obtained concurrently for the same sample allowed us to determine the p value using three independent methods integrated within one instrumentation. The analyte was effectively separated from the interferent, and the acidity values turned out to be consistent with each other. An attempt was also made to replace the standard commercial CE instrument with a home-made portable CE setup. As a result, the similar p value was obtained, at the same time proving the possibility of increasing cost efficiency and reducing energy consumption. Overall, the CE-MST technique has a number of limitations, but its unique analytical capabilities may be beneficial for some applications, especially when sample separation is needed prior to the thermophoretic measurement.
本文首次成功应用毛细管电泳-微尺度热泳串联技术（CE-MST）来测定平衡常数的值，通过使用熔融石英毛细管将 CE 和 MST 仪器在线连接来实现。以荧光素异硫氰酸酯的酸碱离解为例，用酸度常数（p）值来表示。该测量过程包括将含有分析物和故意添加的干扰物的混合物引入 CE 毛细管中，对分析物与干扰物进行电泳分离，用 CE 集成检测器检测分析物，用 MST 检测器检测，然后通过关闭电压源暂时停止流动以进行热泳测量。同时对同一样品进行迁移时间、峰面积和 MST 响应的分析，使我们能够使用三种独立的方法在一个仪器中同时确定 p 值。分析物与干扰物有效分离，酸度值相互一致。同时还尝试用自制的便携式 CE 设备替代标准商业 CE 仪器。结果得到了类似的 p 值，同时也证明了提高成本效益和降低能耗的可能性。总的来说，CE-MST 技术有许多局限性，但它独特的分析能力可能对某些应用有益，特别是在需要在热泳测量之前进行样品分离的情况下。
