Flanigan Paul, Levis Robert
Center for Advanced Photonics Research, Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122; email:
Annu Rev Anal Chem (Palo Alto Calif). 2014;7:229-56. doi: 10.1146/annurev-anchem-071213-020343.
Recent investigations of ambient laser-based transfer of molecules into the gas phase for subsequent mass spectral analysis have undergone a renaissance resulting from the separation of vaporization and ionization events. Here, we seek to provide a snapshot of recent femtosecond (fs) duration laser vaporization and nanosecond (ns) duration laser desorption electrospray ionization mass spectrometry experiments. The former employs pulse durations of <100 fs to enable matrix-free laser vaporization with little or no fragmentation. When coupled to electrospray ionization, femtosecond laser vaporization provides a universal, rapid mass spectral analysis method requiring no sample workup. Remarkably, laser pulses with intensities exceeding 10(13) W cm(-2) desorb intact macromolecules, such as proteins, and even preserve the condensed phase of folded or unfolded protein structures according to the mass spectral charge state distribution, as demonstrated for cytochrome c and lysozyme. Because of the ability to vaporize and ionize multiple components from complex mixtures for subsequent analysis, near perfect classification of explosive formulations, plant tissue phenotypes, and even the identity of the manufacturer of smokeless powders can be determined by multivariate statistics. We also review the more mature field of nanosecond laser desorption for ambient mass spectrometry, covering the wide range of systems analyzed, the need for resonant absorption, and the spatial imaging of complex systems like tissue samples.
最近，基于环境激光将分子转移到气相中以便后续进行质谱分析的研究因汽化和电离过程的分离而再度兴起。在此，我们旨在提供近期飞秒（fs）持续时间激光汽化和纳秒（ns）持续时间激光解吸电喷雾电离质谱实验的简要情况。前者采用小于100 fs的脉冲持续时间，以实现无基质的激光汽化，且几乎没有或完全没有碎片化。当与电喷雾电离相结合时，飞秒激光汽化提供了一种通用、快速的质谱分析方法，无需对样品进行预处理。值得注意的是，强度超过10(13) W cm(-2)的激光脉冲能解吸完整的大分子，如蛋白质，并且根据质谱电荷态分布，甚至能保留折叠或未折叠蛋白质结构的凝聚相，细胞色素c和溶菌酶的情况就是如此。由于能够汽化和电离复杂混合物中的多种成分以便后续分析，通过多变量统计可以近乎完美地确定爆炸物配方、植物组织表型，甚至无烟粉末制造商的身份。我们还回顾了用于环境质谱的纳秒激光解吸这一更为成熟的领域，涵盖所分析的广泛系统、共振吸收的必要性以及像组织样品这样的复杂系统的空间成像。
