Exposure of electrospray droplets to organic vapors was shown to dramatically reduce alkali-metal adduction on protein ions and shift protein charge states. Since DESI-MS is affected by similar adduct species as ESI-MS and shares similar ionization mechanisms, polar organic vapor additives should likewise also improve the DESI-MS analysis of proteins. Here the DESI spray was exposed to a variety of polar organic vapor additives. Head space vapors of polar organic solvents were entrained in nitrogen gas and delivered to the atmosphere inside a semi-enclosed plastic enclosure surrounding the spray plume. The vapors of acetone, acetonitrile, ethyl acetate, methanol, and water were investigated. Vapor dependent effects were observed with respect to changes in protein charge state distributions and signal intensities. With ethyl acetate vapor addition, the signal intensities of all proteins investigated were significantly increased, including proteins larger than 25 kDa such as carbonic anhydrase II and bovine serum albumin.

中文翻译：

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使用 DESI-MS 分析蛋白质期间添加极性有机溶剂蒸气。

电喷雾液滴暴露于有机蒸气中可显着减少碱金属对蛋白质离子的加成作用并改变蛋白质电荷状态。由于 DESI-MS 受与 ESI-MS 相似的加合物种类的影响并具有相似的电离机制，因此极性有机蒸气添加剂同样也应改善蛋白质的 DESI-MS 分析。在这里，DESI 喷雾暴露于各种极性有机蒸汽添加剂。极性有机溶剂的顶部空间蒸气被夹带在氮气中，并被输送到围绕喷雾羽流的半封闭塑料外壳内的大气中。研究了丙酮、乙腈、乙酸乙酯、甲醇和水的蒸气。在蛋白质电荷状态分布和信号强度的变化方面观察到蒸汽依赖效应。随着乙酸乙酯蒸气的加入，