Spontaneous and Forced Modulation of Electrosprays

乔治华盛顿大学的Akos Vertes教授得到了分析和表面化学计划的支持，该计划研究在电喷雾条件下液体中分子的离子形成。尽管这一领域的工作历史悠久，电喷雾电离质谱仪(ESI-MS)在生物分析中的重要性，但我们对相关现象的理解细节仍未解决。这在一定程度上是由于复杂的电流体动力学，必须或多或少同时解决。随着我们对离子溶剂化的理解变得更加复杂，其他的复杂情况也变得明显起来。深入研究了1)液流向带电液滴的分散和2)样品离子从这些液滴中释放的最终阶段。一个实验是使用喷雾电压来调节电喷雾，以便使喷雾与重复地将离子引入飞行时间质量分析仪保持同步。利用相位多普勒风速仪、质谱仪和显微成像技术将液滴的大小和速度分布与观察到的质谱图进行了关联。分子动力学用于研究液滴的破碎和离子的形成。约翰·芬最近因电喷雾电离质谱学(ESI)获得诺贝尔奖，这只是对其影响，特别是其生物化学应用的最公开认可。提高对ESI的理解很可能会产生更大的影响。此外，这项关于液滴和离子形成的基础工作可能会在各种过程中产生科学和技术影响，如云的形成、吸入毒理学和药物输送、纳米加工和操纵以及印刷。

Professor Akos Vertes of George Washington University is supported by the Analytical and Surface Chemistry Program to study the formation of ions from molecules in liquids under electrospray conditions. In spite of the long history of work in this area as well as the importance of Electrospray Ionization Mass Spectrometry (ESI-MS) in bioanalysis, details of our understanding of the associated phenomena remain unresolved. This is due in part to the complicated electro-hydrodynamics that must be addressed more or less simultaneously. Additional complications have become apparent as our understanding of ionic solvation has become more sophisticated. Insight is sought into 1) dispersion of a liquid stream into electrically charged droplets and 2) the ultimate stage of liberation of sample ions from these droplets. One experiment is to modulate the electrospray using the spraying voltage in order to synchronize the spray with the repetitive introduction of ions into the time of flight mass analyzer. Phase Doppler anemometry, mass spectrometry and microscopic imaging are used to correlate (primary) droplet size and velocity distributions with the observed mass spectra. Molecular dynamics is used to study droplet breakup and ion formation. John Fenn's recent Nobel Prize for Electrospray Ionization Mass Spectroscopy (ESI) is only the most public recognition of its impact, and in particular, its biochemical applications. Improved understanding of ESI is highly likely to lead to even more impact. In addition, this fundamental work on droplet and ion formation is likely to have scientific and technical impact in diverse processes such as formation of clouds, inhalation toxicology and drug delivery, nano-processing and manipulation, and printing.