Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Hangzhou 310058, China.
Institute of Microanalytical Systems, Department of Chemistry, Zhejiang University, Hangzhou 310058, China.
Talanta. 2018 Apr 1;180:376-382. doi: 10.1016/j.talanta.2017.12.046. Epub 2017 Dec 16.
In this paper, we describe a robust sheath flow-based CE-MS interface with minimal interface dead volume based on an extended pattern. A 20µm i.d. × 90µm o.d. fused-silica capillary with a chemically-etched thin-wall tip (30µm o.d.) was used as the separation capillary as well as electrospray emitter, and a 200µm i.d. × 375µm o.d. capillary with a tapered tip (40µm o.d.) was used as the sheath flow capillary. An extendable sheath-flow interface mode was adopted by decreasing the thickness of separation capillary tip and extending the separation capillary tip out from the sheath flow capillary tip, and allowing the sheath flow to be transferred to the separation capillary tip along its outer surface, forming a surface sheath flow to mix with sample flow at the separation capillary tip. Such a strategy could significantly reduce the interface dead volume and thus improve the CE separation efficiency and detection sensitivity, as well as evidently enhance the working reliability of the CE-MS interface. We investigated various factors affecting the interface performance, including capillary extending distance, emitter diameters, sheath flow capillary shape, and sheath flow rate. Under the optimized conditions, a minimal interface dead volume of ca. 4pL was obtained which is the smallest one compared with previously-reported sheath flow-based CE-MS interfaces. The feasibility and applicability of the present CE-MS interface were demonstrated in the separation of a peptide mixture with high separation efficiency of 2.07-3.38µm plate heights and good repeatabilities (< 6.1% RSD, n = 5). We except such a simple and robust interface could provide a possible solution for the development of commercial CE-MS interfaces differing from the currently-used ones, and has the potentials to be applied in routine analytical laboratories for various studies such as proteomics, metabolomics, or single cell analysis.
在本文中，我们描述了一种基于扩展模式的具有最小接口死体积的稳健鞘流 CE-MS 接口。使用内径为 20µm、外径为 90µm 的熔融石英毛细管作为分离毛细管和电喷雾发射器，并使用内径为 200µm、外径为 375µm 的带有锥形尖端（外径为 40µm）的毛细管作为鞘流毛细管。通过减小分离毛细管尖端的厚度并将分离毛细管尖端从鞘流毛细管尖端伸出，采用可扩展的鞘流接口模式，允许鞘流沿着其外表面转移到分离毛细管尖端，在分离毛细管尖端形成表面鞘流，与样品流混合。这种策略可以显著减少接口死体积，从而提高 CE 分离效率和检测灵敏度，以及明显增强 CE-MS 接口的工作可靠性。我们研究了影响接口性能的各种因素，包括毛细管伸出距离、喷嘴直径、鞘流毛细管形状和鞘流速度。在优化条件下，获得了约 4pL 的最小接口死体积，与之前报道的鞘流 CE-MS 接口相比，这是最小的接口死体积。本 CE-MS 接口的可行性和适用性在肽混合物的分离中得到了验证，具有 2.07-3.38µm 的板高和良好的重现性（<6.1%RSD，n=5）的高分离效率。我们期望这种简单而稳健的接口能够为开发与当前使用的接口不同的商用 CE-MS 接口提供一种可能的解决方案，并有可能应用于常规分析实验室，用于各种研究，如蛋白质组学、代谢组学或单细胞分析。
