电喷雾电离Electrospray ionization

毛细管尖端施加 2–5 kV 高压，液面在电场中形成泰勒锥并喷出带电液滴。在加热干燥气（氮气）作用下溶剂蒸发，液滴缩小、表面电荷密度增大，达到瑞利极限时发生库仑爆裂，形成更小的液滴，最终通过“离子蒸发”或“带电残基”机制释放气相离子。正离子模式下主要生成 [M+H]⁺、[M+Na]⁺ 或 [M+nH]ⁿ⁺，负离子模式下生成 [M−H]⁻。大分子带多个电荷，使 m/z 落在常规质量分析器范围内，对多电荷峰去卷积即可得到精确分子量。

A 2–5 kV potential at the capillary tip draws the liquid into a Taylor cone that emits charged droplets. Heated drying gas (nitrogen) evaporates the solvent, the droplets shrink and their surface charge density rises until, at the Rayleigh limit, they undergo Coulomb fission into smaller droplets, finally releasing gas-phase ions by the ion-evaporation or charged-residue mechanism. Positive mode gives mainly [M+H]⁺, [M+Na]⁺ or [M+nH]ⁿ⁺, and negative mode [M−H]⁻. Macromolecules carry many charges, bringing m/z into the range of ordinary analysers, and deconvoluting the multiply charged peaks gives an accurate molecular weight.

1968 年多尔用电喷雾产生聚苯乙烯离子束。1984 年山下雅道和约翰·芬恩把电喷雾与质谱结合，1989 年芬恩报道了用 ESI-MS 测定分子量达数万的蛋白质，形象地称为“让分子大象飞起来”。芬恩因此与田中耕一、维特里希共获 2002 年诺贝尔化学奖。

In 1968 Dole used electrospray to produce beams of polystyrene ions. In 1984 Masamichi Yamashita and John Fenn coupled electrospray to a mass spectrometer, and in 1989 Fenn reported ESI-MS of proteins with molecular weights in the tens of thousands, which he described as making 'molecular elephants fly'. Fenn shared the 2002 Nobel Prize in Chemistry with Tanaka and Wüthrich.

ESI 易与液相色谱在线联用（LC-ESI-MS），是蛋白质组学、代谢组学、药物分析、药代动力学、临床检测和环境极性污染物分析的主力技术；还能研究非共价复合物（如蛋白质-配体、蛋白质四级结构）的“天然质谱”以及金属配合物和超分子组装体。

ESI couples readily online with liquid chromatography (LC-ESI-MS) and is the workhorse of proteomics, metabolomics, drug analysis, pharmacokinetics, clinical testing and analysis of polar environmental contaminants; it also enables 'native MS' of non-covalent complexes such as protein–ligand assemblies and quaternary structures, and the study of metal complexes and supramolecular assemblies.