通过分子动力学模拟研究的电喷甲醇/水纳米滴中离子离子的喷射
1Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada.
Journal of the American Chemical Society
|May 20, 2011
概括
将甲醇添加到水滴中显著加快了电喷电离 (ESI) 中的离子喷射和溶剂蒸发. 这种甲醇效应提高了分析物分离和离子排放效率.
科学领域:
- 物理化学 物理化学
- 分析化学 分析化学
- 计算化学计算化学
背景情况:
- 来自纳米滴的溶化离子喷射对于电喷离子化 (ESI) 是至关重要的.
- 以前的分子动力学 (MD) 研究主要研究水系统,而不是ESI中常见的混合溶剂.
- 了解混合溶剂效应对于优化ESI应用至关重要.
研究的目的:
- 用MD模拟来研究含有过量的氨 (NH4+) 离子的混合水/甲醇纳米滴的行为.
- 阐明甲醇对离子喷射,溶剂蒸发和滴滴组成的影响.
- 探索对分析分区和ESI效率的影响.
主要方法:
- 分子动力学 (MD) 模拟在纳米尺寸的水和甲醇滴中进行,其中含有多余的NH4+离子.
- 分析的重点是离子喷射机制,溶剂蒸发率和随着时间的推移而发生的水滴结构变化.
- 与纯水系统和经典离子蒸发模型的比较.
主要成果:
- 甲醇破坏了结网,加速了离子喷射和溶剂蒸发速度.
- 水和甲醇的逃逸速度差异导致滴滴组成和分离的时间依赖变化.
- 在低度的甲醇中,有甲醇丰富的外围形成的分层滴状结构,可能会增强分析物分离.
结论:
- 甲醇显著改变ESI中的纳米滴动力学,增加离子和溶剂逃逸率.
- 滴滴组成的变化和分离现象影响了分析物的行为和ESI效率.
- 离子喷射机制与在自由能量屏障上通过扩散介导的逃逸保持一致,与经典模型相一致.
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