Capillary electrophoresis-mass spectrometry (CE-MS) is a hyphenated technique that combines the advantages like low sample consumption, high separation efficiency, short analytical time in CE and high sensitivity, powerful molecular structure elucidation in MS. Polyimide-coated fused silica capillary has become the most dominant capillary for CE, but it suffers from swelling and aminolysis of polyimide coating when treated with organic solvents and alkaline buffer in the CE-MS interface in which the polyimide coating at the end of the capillary is exposed to the solution, and this phenomenon can result in current instability, irregular electrospray and clogging at outlet after prolonged use. In this work, poly(ether ether ketone) (PEEK) capillary was explored as separation capillary for CE-MS. The problems like swelling and aminolysis of polyimide coating were solved due to the high thermal and chemical stability of PEEK material. After modification with polydopamine, PEEK capillary (PD-PEEK) can generate adjustable electroosmotic flow and provide good separation selectivity. The zwitterion polymer of polydopamine can provide cathodic electroosmotic flow (EOF) at high pH value (pH ≥ 5) and anodic EOF at low pH value (pH ≤ 4), and the EOF mobility can also be adjusted by controlling the modification time of polydopamine. Good separation performance was obtained in the analysis for several classes of compounds including amino acids, phenols and plant hormones at rational EOF direction. Repeatability of the PD-PEEK capillary was studied, with relative standard deviations for intra-day, inter-day runs and between tubes less than 4.94%.

中文翻译：

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用于毛细管电泳-质谱分析的聚多巴胺功能化聚（醚醚酮）管

毛细管电泳-质谱 (CE-MS) 是一种联用技术，它结合了样品消耗少、分离效率高、CE 分析时间短和 MS 高灵敏度、强大的分子结构解析等优点。聚酰亚胺涂层的熔融石英毛细管已成为 CE 最主要的毛细管，但在毛细管末端的聚酰亚胺涂层的 CE-MS 界面中用有机溶剂和碱性缓冲液处理时，它会遭受聚酰亚胺涂层的溶胀和氨解暴露在溶液中，这种现象会导致电流不稳定，长时间使用后电喷不规则和出口堵塞。在这项工作中，聚醚醚酮 (PEEK) 毛细管被用作 CE-MS 的分离毛细管。由于PEEK材料的高热稳定性和化学稳定性，解决了聚酰亚胺涂层的溶胀和氨解等问题。聚多巴胺改性后的PEEK毛细管（PD-PEEK）可以产生可调的电渗流并提供良好的分离选择性。聚多巴胺的两性离子聚合物可以在高pH值（pH≥5）下提供阴极电渗流（EOF）和在低pH值（pH≤4）下提供阳极EOF，并且还可以通过控制聚多巴胺的改性时间来调节EOF迁移率. 在合理的EOF方向对氨基酸、酚类和植物激素等几类化合物进行了分析，获得了良好的分离效果。研究了 PD-PEEK 毛细管的可重复性，日内、日间运行和管之间的相对标准偏差小于 4.94%。