Fast and direct screening of polyaromatic hydrocarbon (PAH)‐contaminated sand using a miniaturized membrane inlet mass spectrometer (mini‐MIMS)

Abstract

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.

Direct detection of benzene, toluene, and ethylbenzene at trace levels in ambient air by atmospheric pressure chemical ionization using a handheld mass spectrometer

“…For example, SCIEX triple quadrupoles were introduced in the 1980s to address this very problem, e.g., the Mississauga disaster was monitored in this way [17], although these successful systems were transportable, not portable [18,19]. Several versions of portable mass spectrometers have been used for in situ gasphase chemical analysis [20,21] based on selective membrane sampling [22][23][24][25]. A related sorbent introduction system using preconcentration in a solid matrix and thermal release was employed to achieve trace level detection of benzene with the handheld Mini 10.5 [26].…”

Fast and direct screening of solid materials for their potential liberation of hydrophobic organic compounds using hot cell membrane inlet mass spectrometry

“…The homemade integrated hot cell membrane inlet/ion source system is very similar in design to the sample cell system that we introduced in 1998 for the analysis of flavor compounds directly from microbial media 26. A schematic diagram of the construction principles of our sample cells was shown in the original paper26 and a photograph showing the hot sample cell used recently for soil analysis has also been published 25. The major difference between the earlier sample cells and the present system is that the closed ion source is removed from the mass spectrometer and built into one side of a vacuum flange, whereas the sample cell is attached to the other side of the flange.…”

“…Recently, we demonstrated that sand and soil samples can be directly and quantitatively analyzed for their content of polyaromatic hydrocarbons (PAHs) simply by inserting a sample vial with the contaminated sample into a hot (170°C) cell with a membrane interface to the electron ionization (EI) source of a mass spectrometer 25. The present paper explores the possibility of using the hot cell MIMS technique as a general tool for fast and direct screening of solid materials for their potential liberation of chemicals.…”

An in-source stretched membrane inlet for on-line analysis of VOCs in water with single photon ionization TOFMS

“…However, the pressure of 10 À3 Pa inside the SPI source limited the sample input, and the limit of detection (LOD) of benzene was only 25 mg L À1 . Other types of membrane inlet have also been developed to improve the performance of on-line mass spectrometry, [13][14][15][16][17][18][19][20][21][22][23][24] such as the direct external probe hollow ber membrane (HFM), 25 the direct ow-through HFM probe, 13,26 the trap-and-release HFM, 15,21 the intermediate pressure region membrane and the single-side membrane etc.…”