Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan.
J Am Soc Mass Spectrom. 2010 Sep;21(9):1547-53. doi: 10.1016/j.jasms.2010.04.021. Epub 2010 May 6.
In this paper, we describe a novel technique--ultrasonication-assisted spray ionization (UASI)--for the generation of singly charged and multiply charged gas-phase ions of biomolecules (e.g., amino acids, peptides, and proteins) from solution; this method employs a low-frequency ultrasonicator (ca. 40 kHz) in place of the high electric field required for electrospray ionization. When a capillary inlet is immersed into a sample solution within a vial subjected to ultrasonication, the solution is continually directed to the capillary outlet as a result of ultrasonication-assisted capillary action; an ultrasonic spray of the sample solution is emitted at the outlet of the tapered capillary, leading to the ready generation of gas-phase ions. Using an ion trap mass spectrometer, we found that singly charged amino acid and multiply charged peptides/proteins ions were generated through this single-step operation, which is both straightforward and extremely simple to perform. The setup is uncomplicated: only a low-frequency ultrasonicator and a tapered capillary are required to perform UASI. The mass spectra of the multiply charged peptides and proteins obtained from sample solutions subjected to UASI resemble those observed in ESI mass spectra.
在本文中，我们描述了一种新颖的技术——超声喷雾离子化（UASI）——用于从溶液中生成生物分子（例如氨基酸、肽和蛋白质）的单电荷和多电荷气相离子；该方法采用低频超声（约 40 kHz）代替电喷雾电离所需的高电场。当毛细管入口浸入小瓶内的样品溶液中并进行超声处理时，由于超声辅助的毛细管作用，溶液会不断被引导至毛细管出口；在锥形毛细管的出口处喷出超声喷雾，从而容易产生气相离子。使用离子阱质谱仪，我们发现通过这种简单的一步操作可以生成单电荷氨基酸和多电荷肽/蛋白质离子，操作既简单又直接。该装置结构简单：只需低频超声和锥形毛细管即可进行 UASI。从小瓶中样品溶液得到的多电荷肽和蛋白质的质谱与在 ESI 质谱中观察到的相似。
