生命科学研究の分野では最近のMSイオン化やインターフェイスの発達で生物中の代謝物を直接観測でき、MSイメージ画像の取得が可能となっている。直接生物をMSで観測する手法は生物学のみならず、化学や物理学の分野でも注目度が高い。幅広い代謝物全般へのイオン化研究や、測定条件の最適化、組織中でのマトリックス効果の研究など、個々別々の広範な工夫とそれを統合する系統的な研究も必須となっている。今回は一般に知られているいろいろなイオン化法の実例とイオン化メカニズムの討論や生物直接MS観測における工夫などを紹介・議論したい。MALDI－MSイメージング、探針プローブイオン化法（PESI）、脱離エレクトロスプレーイオン化法（DESI）、Direct Analysis in Real Timeイオン化法（DART）などの「イオン化」と生物直接MS観測というキーワードで、応用からイオン化メカニズムまでの最先端の研究を紹介したい。
チェンリーチュイン 先生 （山梨大学）
Lee Chuin Chen (University of Yamanashi)
Ambient mass spectrometry is not necessary equal to ambient ionization mass spectrometry: A brief review on ESI based ion sources operated under vacuum, atmospheric pressure and super-atmospheric pressure.
“Ambient mass spectrometry” analyzes the sample when the specimens of interest are in their native environment, which is mostly atmospheric pressure ambient. This term, which is nearly synonymous with “in-situMS,”first appeared in Science (vol. 311 pp. 1566-1570, 2006) to describe the ambient ionization capability of DESI and DART. Since then, another more refined term, “ambient ionization mass spectrometry” had also appeared in the literature to cover all kinds of atmospheric pressure ion source that can deal with raw samples directly without, or with minimum clean-up or separation step. The ion formation is therefore, by definition, under the ambient pressure. It is our argument that in order to achieve the ambient or in-situ, mass spectrometry, only the sampling process needs to be done under the native ambient environment, the ionization of the sampled material however, can be done separately under vacuum, atmospheric pressure, or even super-atmospheric pressure. Some of these examples will be given.
In this presentation, we will give a brief review, mostly on the electrospray ionization based techniques that have been developed in the University of Yamanashi. It will cover some of the recent progress in the medical diagnosis system based on Hiraoka’s probe electrospray ionization (PESI), and two novel electrospray ion sources that are operated under vacuum, and high pressure condition. We will also highlight some recent work on the ultra-fast digestion mass spectrometry that combines the chemical digestion and online ESI ionization into a single step process that allows the digestion MS (which usually takes several hours or a whole day to complete) to be done in just a few seconds. Hyphenation and interfacing technique using novel vacuum FAIMS will also be briefly discussed.
