New Mechanism of Extractive Electrospray Ionization Mass Spectrometry for Heterogeneous Solid Particles
New Mechanism of Extractive Electrospray Ionization Mass Spectrometry for Heterogeneous Solid Particles
复制标题
异质固体颗粒萃取电喷雾电离质谱新机制
DOI：
10.1021/acs.analchem.7b01464
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发表时间：
2018
影响因子：
7.4
通讯作者：
Finlayson-Pitts, B. J.
中科院分区：
文献类型：
--
作者：
Kumbhani, S.;Longin, T.;Wingen, L.M.;Kidd, C.;Perraud, V.;Finlayson-Pitts, B. J.
空气中颗粒物的实时原位质谱分析在几个应用中非常重要，包括环境空气中的暴露研究，工业环境以及评估对能见度和气候的影响。然而，获得分子和3D结构信息更具挑战性，特别是对于异质固体或半固体颗粒。本文报道了萃取电喷雾电离质谱（EESI-MS）用于有机涂层固体颗粒分析的研究。其目的是阐明有多少总颗粒含量的采样，并确定该技术的灵敏度的表面层。结果表明，对于用谷氨酸（GA）涂覆的NaNO 3颗粒，与GA涂层相比，很少的固体NaNO 3核心被取样，而对于用丙二酸（MA）涂覆的GA颗粒，观察到来自MA涂层和GA核心的显著信号。然而，在两种情况下，与EESI-MS相比，在Teflon过滤器上收集的相同样品的常规ESI-MS（然后提取）检测到更多的核心材料。这些结果表明，对于这里使用的实验条件，EESI-MS不对整个颗粒进行采样，而是对表面层更敏感。对NaNO 3、GA或柠檬酸的单组分颗粒的单独实验表明，溶解必须有动力学限制，这在确定EESI-MS灵敏度中很重要。我们提出了一个新的EESI溶剂液滴与固体颗粒相互作用的机制，这是与实验观察一致。结合以前的EESI-MS研究的有机颗粒，这些结果表明，EESI不一定采样整个颗粒时，固体，不仅溶解度，而且表面能和溶解动力学起着重要的作用。
Real-time in situ mass spectrometry analysis of airborne particles is important in several applications, including exposure studies in ambient air, industrial settings, and assessing impacts on visibility and climate. However, obtaining molecular and 3D structural information is more challenging, especially for heterogeneous solid or semisolid particles. We report a study of extractive electrospray ionization mass spectrometry (EESI-MS) for the analysis of solid particles with an organic coating. The goal is to elucidate how much of the overall particle content is sampled, and determine the sensitivity of this technique to the surface layers. It is shown that, for NaNO3particles coated with glutaric acid (GA), very little of the solid NaNO3core is sampled compared to the GA coating, whereas for GA particles coated with malonic acid (MA), significant signals from both the MA coating and the GA core are observed. However, conventional ESI-MS of the same samples collected on a Teflon filter (and then extracted) detects much more core material compared to EESI-MS in both cases. These results show that, for the experimental conditions used here, EESI-MS does not sample the entire particle but, instead, is more sensitive to surface layers. Separate experiments on single-component particles of NaNO3, GA, or citric acid show that there must be a kinetics limitation to dissolution that is important in determining EESI-MS sensitivity. We propose a new mechanism of EESI solvent droplet interaction with solid particles that is consistent with the experimental observations. In conjunction with previous EESI-MS studies of organic particles, these results suggest that EESI does not necessarily sample the entire particle when solid, and that not only solubility but also surface energies and the kinetics of dissolution play an important role.