ThoMSon Mass Spectrometry Laboratory, Institute of Chemistry, University of Campinas-UNICAMP, Campinas, SP, Brazil.
Anal Chem. 2011 Feb 15;83(4):1375-80. doi: 10.1021/ac102765z. Epub 2011 Jan 14.
The development and illustrative applications of an ambient ionization technique termed Venturi easy ambient sonic-spray ionization (V-EASI) is described. Its dual mode of operation with Venturi self-pumping makes V-EASI applicable to the direct mass spectrometric analysis of both liquid (V(L)-EASI) and solid (V(S)-EASI) samples. V-EASI is simple and easy to assemble, operating solely via the assistance of a sonic stream of nitrogen or air. The sonic gas stream causes two beneficial and integrated effects: (a) the self-pumping of solutions via the Venturi effect and (b) sonic-spray ionization (SSI) of analytes either in solution or resting on solid surfaces. In its liquid mode, V(L)-EASI is applicable to analytes in solution, forming negatively and/or positively charged intact molecular species in a soft fashion with little or no fragmentation. In its solid mode, V(S)-EASI relies on Venturi self-pumping of a proper SSI solvent solution in combination with SSI to form a stream of bipolar charged droplets that bombard the sample surface, causing desorption and ionization of the analyte molecules. As for its precursor technique (EASI), V-EASI generates bipolar droplets with considerably lower average charging, which increases selectivity for ionization with high signal-to-noise ratios and clean spectra dominated by single molecular species with minimal solvent ions. V-EASI also operates in a voltage-, heat-, and radiation-free fashion and is therefore free of thermal, electrical, or discharge interferences.
本文描述了一种称为文丘里易环境声喷雾电离（V-EASI）的环境离子化技术的发展和应用实例。它的双重操作模式与文丘里自吸作用相结合，使得 V-EASI 适用于液体（V(L)-EASI）和固体（V(S)-EASI）样品的直接质谱分析。V-EASI 简单易用，仅通过氮气或空气的声波流的辅助即可操作。声波气体流产生了两个有益且集成的效果：（a）通过文丘里效应自吸溶液；（b）对溶液中的分析物或停留在固体表面上的分析物进行声喷雾电离（SSI）。在其液体模式下，V(L)-EASI 适用于溶液中的分析物，以柔和的方式形成带负电荷和/或正电荷的完整分子物种，几乎没有或没有碎片化。在其固体模式下，V(S)-EASI 依赖于文丘里自吸合适的 SSI 溶剂溶液与 SSI 的组合，形成一股双极带电液滴流，轰击样品表面，导致分析物分子的解吸和电离。作为其前体技术（EASI），V-EASI 产生的双极液滴具有明显较低的平均充电，这提高了具有高信噪比和干净谱图的电离选择性，谱图主要由单分子物种组成，溶剂离子极少。V-EASI 还以无电压、无热量和无辐射的方式运行，因此没有热、电或放电干扰。
