Kist Tarso B Ledur
Laboratory of Instrumentation and Automation in Analytical Chemistry, Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
Laboratory of Optical Sensors, PEA, University of São Paulo (USP), São Paulo, SP, Brazil.
J Sep Sci. 2025 Feb;48(2):e70081. doi: 10.1002/jssc.70081.
The heat generated by the Joule effect during capillary electrophoresis (CE) runs creates radial temperature gradients in the separation medium. These temperature gradients cause zone dispersion in addition to molecular diffusion. This severely limits the field strengths that can be applied during the runs, especially when solutions with high ionic conductivity are used. This greatly increases run times, especially when high separation efficiencies are sought. In this work, the author proposes tying cooling capillaries (fused silica microtubes) along the external surface of the analytical capillary, allowing the circulation of coolants to efficiently and symmetrically control temperature in CE. The author deduced, step-by-step, the three master equations that serve as guidelines to produce a good match and tightly secure cooling capillaries along the outer surface of analytical capillaries. Additionally, an automated capillary tying machine was developed and demonstrated. Sets were produced with: four, five, and six cooling capillaries tied around one analytical capillary. The outer diameters of the capillaries used (one analytical and cooling) and the values of the remaining voids left between the first and last cooling capillary are in good agreement with the predictions of the three master equations deduced in this work. To the author's knowledge, this is the first time that cooling capillaries were tied around analytical capillaries to produce an efficient and symmetric cooling system for CE and toroidal capillary electrophoresis.
毛细管电泳（CE）运行过程中焦耳效应产生的热量会在分离介质中形成径向温度梯度。这些温度梯度除了会导致分子扩散外，还会引起区带展宽。这严重限制了运行过程中可施加的场强，尤其是在使用高离子电导率溶液时。这极大地增加了运行时间，特别是在追求高分离效率时。在这项工作中，作者提出将冷却毛细管（熔融石英微管）绑在分析毛细管的外表面，使冷却剂循环以有效且对称地控制毛细管电泳中的温度。作者逐步推导了三个主要方程，这些方程可作为在外表面上良好匹配并紧密固定冷却毛细管的指导原则。此外，还开发并展示了一台自动毛细管绑扎机。制作了几套样品：将四根、五根和六根冷却毛细管绑在一根分析毛细管周围。所用毛细管（一根分析毛细管和冷却毛细管）的外径以及第一根和最后一根冷却毛细管之间剩余空隙的值与这项工作中推导的三个主要方程的预测结果高度吻合。据作者所知，这是首次将冷却毛细管绑在分析毛细管周围，以产生用于毛细管电泳和环形毛细管电泳的高效且对称的冷却系统。
