Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States.
J Am Soc Mass Spectrom. 2020 Jul 1;31(7):1499-1508. doi: 10.1021/jasms.0c00044. Epub 2020 Jun 2.
Analytical characteristics of contained electrospray ionization (ESI) are summarized in terms of its potential to modify the analyte solution during the stages of droplet formation to provide opportunities to generate native versus denatured biomolecular gas-phase ions, without the need for bulk-phase analyte modifications. The real-time modification of the charged microdroplets occurs in a cavity that is included in the outlet of the contained-ESI ion source. Close examination of the inside of the cavity using a high-speed camera revealed the formation of discrete droplets as well as thin liquid films in the droplets wake. When operated at 20 psi N pressure, the droplets were observed to move at an average speed of 8 mm/s providing ∼1 s mixing time in a 10 mm cavity length. Evidence is provided for the presence of highly reactive charged droplets based on myoglobin charge state distribution, apo-myoglobin contents, and ion mobility drift time profiles under different spray conditions. Mechanistic insights for the capture of vapor-phase reagents and droplet dynamics as influenced by different operational modes are also described.
密闭电喷雾（ESI）的分析特性，概括来说，就是在液滴形成的各个阶段，有潜力对分析物溶液进行修饰，从而有机会生成天然态或变性的生物分子气相离子，而无需对本体相分析物进行修饰。在包含 ESI 离子源出口处的腔内，实时对带电微液滴进行修饰。使用高速摄像机对腔内部进行仔细检查，发现在微液滴的尾迹中形成了离散的液滴以及薄的液体膜。在 20 psi N 压力下，观察到液滴以 8mm/s 的平均速度移动，在 10mm 长的腔体内提供了约 1s 的混合时间。基于肌红蛋白电荷状态分布、脱辅肌红蛋白含量以及不同喷雾条件下的离子迁移率漂移时间谱，为存在高反应性带电液滴提供了证据。还描述了不同操作模式下蒸气相试剂的捕获和液滴动力学的机制见解。
