Characterisation of a micro-plasma for ambient mass spectrometry imaging.
Characterisation of a micro-plasma for ambient mass spectrometry imaging.
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DOI：
10.1039/c4an01110d
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发表时间：
2014-09
期刊：
影响因子：
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通讯作者：
A. Bowfield;J. Bunch;T. Salter;R. Steven;I. Gilmore;David A. Barrett;M. Alexander;K. McKay;J. Bradley
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文献类型：
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作者：
A. Bowfield;J. Bunch;T. Salter;R. Steven;I. Gilmore;David A. Barrett;M. Alexander;K. McKay;J. Bradley
介绍了用于环境质谱成像的非热大气压微等离子体离子源的表征和优化结果。实验的几何结构经过优化，可以产生最强烈和最稳定的离子信号。信号稳定性（相对标准偏差）达到2.3-6.5%的总离子电流测量从色谱图。利用这些参数对聚四氟乙烯/玻璃样品进行光栅扫描，以147±31 μm的空间分辨率实现质谱成像。还对分辨率作为采集参数的函数进行了系统研究，以支持未来的技术发展。在负离子模式下，从PTFE/玻璃样品边缘获得质谱，并用于构造图像以计算空间分辨率。利用在聚四氟乙烯光谱中观察到的优势离子的强度变化构建图像。来自聚合物的质谱在200-500 Da的m/z光谱窗口中由三个系列离子主导。这些离子的间距为50 Da，化学式为[C2F + [CF2]n]（-）、[CF + [CF2]n + O]（-）和[CF + [CF2]n + O3]（-）。产生这些离子的机制似乎是聚合物链断裂，然后通过大气离子内合电离。以质子萃取/质子化分子离子为主的个人护理用品、氨基酸和药品的正离子和负离子模式质谱，突出了该装置的潜在应用领域。为了进一步实现这一目标，作者利用1,8-桉树脑分子可能片段的强度变化构建了豆蔻种子的质谱图像，以揭示其在食品和其他生物材料成像中的潜在应用。
Results are presented on the characterisation and optimisation of a non-thermal atmospheric pressure micro-plasma ion source used for ambient mass spectrometry imaging. The geometry of the experiment is optimised to produce the most intense and stable ion signals. Signal stabilities (relative standard deviation) of 2.3-6.5% are achieved for total ion current measurements from chromatograms. Parameters are utilised to achieve MS imaging by raster scanning of PTFE/glass samples with a spatial resolution of 147 ± 31 μm. A systematic study of resolution as a function of acquisition parameters was also undertaken to underpin future technique development. Mass spectra are obtained from PTFE/glass sample edges in negative ion mode and used to construct images to calculate the spatial resolution. Images are constructed using the intensity variation of the dominant ion observed in the PTFE spectrum. Mass spectra originating from the polymer are dominated by three series of ions in a m/z spectral window from 200-500 Da. These ions are each separated by 50 Da and have the chemical formula [C2F + [CF2]n](-), [CF + [CF2]n + O](-) and [CF + [CF2]n + O3](-). The mechanism for the generation of these ions appears to be a polymer chain scission followed by ionisation by atmospheric ion adduction. Positive and negative ion mode mass spectra of personal care products, amino acids and pharmaceuticals, dominated by the proton abstracted/protonated molecular ion, highlight the potential areas of application for such a device. Further to this end a mass spectral image of cardamom seeds, constructed using the variation in intensity of possible fragments of the 1,8-cineole molecule, is included to reveal the potential application to the imaging of foods and other biological materials.