Super-atmospheric pressure ionization mass spectrometry and its application to ultrafast online protein digestion analysis.
Ion source pressure plays a significant role in the process of ionization and the subsequent ion transmission inside a mass spectrometer. Pressurizing the ion source to a gas pressure greater than atmospheric pressure is a relatively new approach that aims to further improve the performance of atmospheric pressure ionization sources. For example, under a super-atmospheric pressure environment, a stable electrospray can be sustained for liquid with high surface tension such as pure water, because of the suppression of electric discharge. Even for nano-electrospray ionization (nano-ESI), which is known to work with aqueous solution, its stability and sensitivity can also be enhanced, particularly in the negative mode when the ion source is pressurized. A brief review on the development of super-atmospheric pressure ion sources, including high-pressure electrospray, field desorption and superheated ESI, and the strategies to interface these ion sources to a mass spectrometer will be given. Using a recent ESI prototype with an operating temperature at 220 °C under 27 atm, we also demonstrate that it is possible to achieve an online Asp-specific protein digestion analysis in which the whole processes of digestion, ionization and MS acquisition could be completed on the order of a few seconds. This method is fast, and the reaction can even be monitored on a near-real-time basis. Copyright © 2016 John Wiley & Sons, Ltd.
Graduate School, Department of Interdisciplinary Research, University of Yamanashi, 4-3-11, Takeda, Kofu, Yamanashi, 400-8511, Japan.
Lee Chuin
LC
Chen
Graduate School, Department of Interdisciplinary Research, University of Yamanashi, 4-3-11, Takeda, Kofu, Yamanashi, 400-8511, Japan.
Satoshi
S
Ninomiya
Clean Energy Research Center, University of Yamanashi, 4-3-11, Takeda, Kofu, Yamanashi, 400-8511, Japan.
Kenzo
K
Hiraoka
D000818:Animals; D001274:Atmospheric Pressure; D004867:Equipment Design; D006358:Hot Temperature; D006801:Humans; D011506:Proteins / Q000737:chemistry*; D059748:Proteolysis; D021241:Spectrometry, Mass, Electrospray Ionization / Q000191:economics / Q000295:instrumentation / Q000379:methods*
D011506:Proteins
high-pressure electrospray; non-vacuum field desorption; pressurized hot water; rapid non-enzymatic digestion; subcritical water; super-atmospheric pressure ionization