Department of Chemistry and Biochemistry, Saint Louis University, 3501 Laclede Avenue, St. Louis, Missouri 63103, United States.
Department of Chemistry and Biochemistry, Rowan University, 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States.
J Am Soc Mass Spectrom. 2022 Oct 5;33(10):1825-1832. doi: 10.1021/jasms.2c00134. Epub 2022 Sep 1.
Supercritical fluids are typically electrosprayed using an organic solvent makeup flow to facilitate continuous electrical connection and enhancement of electrospray stability. This results in sample dilution, loss in sensitivity, and potential phase separation. Premixing the supercritical fluid with organic solvent has shown substantial benefits to electrospray efficiency and increased analyte charge state. Presented here is a nanospray mass spectrometry system for supercritical fluids (nSF-MS). This split flow system used small i.d. capillaries, heated interface, inline frit, and submicron emitter tips to electrospray quaternary alkyl amines solvated in supercritical CO with a 10% methanol modifier. Analyte signal response was evaluated as a function of total system flow rate (0.5-1.5 mL/min) that is split to nanospray a supercritical fluid with linear flow rates between 0.07 and 0.42 cm/sec and pressure ranges (15-25 MPa). The nSF system showed mass-sensitive detection based on increased signal intensity for increasing capillary i.d. and analyte injection volume. These effects indicate efficient solvent evaporation for the analysis of quaternary amines. Carrier additives generally decreased signal intensity. Comparison of the nSF-MS system to the conventional SF makeup flow ESI showed 10-fold signal intensity enhancement across all the capillary i.d.s. The nSF-MS system likely achieves rapid solvent evaporation of the SF at the emitter point. The developed system combined the benefits of the nanoemitters, sCO, and the low modifier percentage which gave rise to enhancement in MS detection sensitivity.
超临界流体通常使用有机溶剂组成流进行电喷雾，以促进连续的电连接并增强电喷雾的稳定性。这会导致样品稀释、灵敏度降低以及潜在的相分离。将超临界流体与有机溶剂预混合已显示出对电喷雾效率和增加分析物荷电态有很大的益处。本文介绍了一种用于超临界流体的纳米喷雾质谱系统 (nSF-MS)。该分流流系统使用小内径毛细管、加热接口、在线 frit 和亚微米发射器尖端，将在超临界 CO 中溶解的季铵盐在 10%甲醇改性剂中进行电喷雾。通过总系统流速 (0.5-1.5 mL/min) 的函数评估分析物信号响应，该流速分流至纳米喷雾以线性流速在 0.07 和 0.42 cm/sec 之间和压力范围 (15-25 MPa)。nSF 系统显示出基于毛细管内径和分析物注入体积增加的信号强度增加的质量敏感检测。这些效应表明，对于季铵盐的分析，溶剂蒸发效率很高。载流添加剂通常会降低信号强度。将 nSF-MS 系统与传统的 SF 组成流 ESI 进行比较，在所有毛细管内径下都显示出 10 倍的信号强度增强。nSF-MS 系统可能在发射器处实现了 SF 的快速溶剂蒸发。所开发的系统结合了纳米发射器、sCO 和低改性剂百分比的优点，从而提高了 MS 检测灵敏度。
