Itzenhäuser Patricia, Wachter Ferdinand Max, Lehmann Laura, Rajkovic Michelle, Benter Thorsten, Wißdorf Walter
Department of Physical and Theoretical Chemistry, University of Wuppertal, Gaussstrasse 20, 42119 Wuppertal, Germany.
J Am Soc Mass Spectrom. 2024 Oct 2;35(10):2429-2439. doi: 10.1021/jasms.4c00238. Epub 2024 Sep 10.
Electrospray ionization (ESI) enables coupling between liquid chromatography (LC) and mass spectrometry (MS). Since it is a gentle ionization method, it is frequently used for the analysis of large biomolecules. In recent years, several experimental setups have demonstrated that the use of ESI results in the formation of charged droplets that are aspirated into the vacuum systems of mass spectrometers. This results in a variety of consequences, such as instrument contamination, which can impede the analytical performance. We investigate the signatures of aspirated charged droplets with a commercial LC-ESI-MS system at analytical conditions. Previous observations without LC coupling are reproduced and show that significant droplet aspiration is probably taking place at analytical LC-ESI-MS conditions. This common phenomenon likely decreases the instrument sensitivity. Analyte can be released by isolation and fragmentation of droplet fragments; thus, aspirated droplets can mask analyte even in the mass analyzer region. The complex morphology of droplet MS/MS mass spectra is highly reproducible at the same experimental conditions. This implies the existence of distinct molecular reaction pathways of the droplet fragments. To assess the effect of droplet aspiration on analytical applications, relevant method and ion source parameters, which are commonly varied during method optimization, were investigated. Further variations of the solvent composition revealed that the aspirated droplets and their fragmentation are particularly sensitive to the solvent composition and thus also to the LC solvent gradient in an analytical experiment.
电喷雾电离（ESI）实现了液相色谱（LC）与质谱（MS）的联用。由于它是一种温和的电离方法，常用于分析大型生物分子。近年来，一些实验装置表明，使用ESI会导致形成带电液滴，这些液滴会被吸入质谱仪的真空系统。这会产生多种后果，如仪器污染，进而可能影响分析性能。我们在分析条件下使用商用LC-ESI-MS系统研究了被吸入的带电液滴的特征。重现了之前未与LC联用的观察结果，结果表明在分析型LC-ESI-MS条件下可能会发生显著的液滴吸入现象。这种常见现象可能会降低仪器灵敏度。分析物可通过液滴碎片的分离和裂解而释放出来；因此，即使在质量分析器区域，被吸入的液滴也可能掩盖分析物。在相同实验条件下，液滴MS/MS质谱的复杂形态具有高度可重复性。这意味着液滴碎片存在独特的分子反应途径。为了评估液滴吸入对分析应用的影响，我们研究了在方法优化过程中通常会变化的相关方法和离子源参数。溶剂组成的进一步变化表明，被吸入的液滴及其裂解对溶剂组成特别敏感，因此在分析实验中也对LC溶剂梯度敏感。
