Frandsen Helle, Janfelt Christian, Lauritsen Frants R
Department of Chemistry, Copenhagen University, Universitetsparken 5, 2100 Copenhagen Ø, Denmark.
Rapid Commun Mass Spectrom. 2007;21(10):1574-8. doi: 10.1002/rcm.3000.
A miniaturized membrane inlet mass spectrometer (mini-MIMS; total weight 10 kg everything included) was equipped with a small sample cell using a flat sheet silicone membrane mounted close to the ionizing region of a multipole mass spectrometer. Spiked sand samples were placed in small stainless steel vials and dropped into the heated sample cell (>150 degrees C). A hole in the vial in front of the membrane and above the sand made it possible for the polyaromatic hydrocarbon (PAH) residuals to penetrate the membrane and enter the mass spectrometer as they evaporated from the sample. Using this simple setup we were able to quantitatively (approximately 10% relative standard deviation (RSD)) detect PAHs with up to five aromatic rings and with detection limits in the low parts-per-million (ppm) range. The vial system solves one of the major difficulties in analysis of larger PAHs using a MIMS. Normally, analysis of PAHs with more than two rings is hampered by a long memory effect due to the sticking of the PAHs to the inlet system, the membrane and surfaces in the vacuum system. By removing the vial from the sample cell within 2 min, we were able to analyze samples at 5-10 min intervals. The preliminary laboratory experiments presented here show much promise with respect to the development of a hand held (<10 kg) on-site mass spectrometry system for PAH screening at contaminated sites.
一台小型化膜进样质谱仪（mini - MIMS；包括所有部件在内总重10千克）配备了一个小型样品池，该样品池使用了一块平板硅胶膜，安装在多极质谱仪的电离区域附近。将加标砂样放置在小型不锈钢小瓶中，然后放入加热的样品池（>150摄氏度）。小瓶上位于膜前方且在砂样上方的一个孔，使得多环芳烃（PAH）残余物在从样品中蒸发时能够穿透膜并进入质谱仪。使用这种简单装置，我们能够定量（相对标准偏差（RSD）约为10%）检测多达五个芳环的PAH，检测限在百万分之几（ppm）的低范围内。小瓶系统解决了使用MIMS分析较大PAH时的一个主要难题。通常，由于PAH粘附在进样系统、膜以及真空系统中的表面上，具有两个以上环的PAH分析会受到长记忆效应的阻碍。通过在2分钟内将小瓶从样品池中取出，我们能够以5 - 10分钟的间隔分析样品。此处展示的初步实验室实验对于开发一种用于在污染场地进行PAH筛查的手持式（<10千克）现场质谱系统很有前景。
