Development of Multi-Membrane Near-Infrared Diode Mass Spectrometer for Field Analysis of Aromatic Hydrocarbons

Abstract

Abstract. Membrane Inlet Mass Spectrometry (MIMS) is a technique that incorporates a semi-permeable membrane selective for differing organic molecules and chemistries. This eliminates the need for time-consuming sample preparation and facilitates near instantaneous analysis. This study will examine how the front end of MIMS incorporates three dual inlet ports, allowing for differing MIMS materials and selectivity for specific environments. Polydimethylsiloxane (PDMS) membranes have proven to be selective of benzene, toluene, and xylene (BTX) as well as aromatic hydrocarbons that are common in petroleum products while remaining selective against the aliphatic chains. PDMS has proven to be a successful choice of membrane with high permeability in atmospheric environments. In addition, polycyclic aromatic hydrocarbons (PAHs) such as acenaphthene, acenapthylene, naphthalene, and fluorene have recently been detected to the 5 ppb level in a nitrogen atmosphere with our current configuration. This preliminary work provides proof of concept using near-infrared laser diodes that act upon the membrane to increase its permeability and provide higher sensitivity of aromatic samples.

In-Situ Analysis of Essential Fragrant Oils Using a Portable Mass Spectrometer

“…Cooks and Ouyang pioneered the on-site analysis of condensed-phase and semivolatile organics in aqueous phase using small footprint miniaturized quadrupole ion trap based systems combined with a membrane inlet probe [40, 43–48]. Other groups have developed portable MIMS systems [49, 50] focusing on the development of portable quadrupole mass filters coupled with membrane inlet sampling for the direct in-situ analysis of a wide range of volatile organic compounds (VOCs) and semi-VOCs in both gaseous and aqueous phase [49, 51–55]. Most recently a series of VOCs have been used to encapsulate and modulate data using a portable MS coupled with a direct inlet membrane probe with high sensitivity [56].…”

High pressure mass spectrometry of volatile organic compounds with ambient air buffer gas

“…[1] HPMS provides a path forward for the development of portable MS by reducing the overall vacuum requirements and eliminating the need for large, complex, and fragile pumping systems that include turbomolecular pumps. Other miniature mass spectrometers have been developed for many applications including forensics, [2,3] environmental monitoring, [4][5][6] detection of explosives [7] or chemical warfare agents, [8,9] and clinical analyses. [10] Two recent reviews cover miniature and portable mass spectrometers for these and other applications, as well as the future directions of MS miniaturization.…”

Condensed Phase Membrane Introduction Mass Spectrometry with Direct Electron Ionization: On-line Measurement of PAHs in Complex Aqueous Samples

“…Although PAHs are very hydrophobic (typical log K ow values in the 3-6 range [16]), making them well suited for PDMS based MIMS measurements, their low volatilities make their direct, on-line measurement by GP-MIMS problematic. Thermally assisted GP-MIMS approaches have been used to measure selected PAHs [18][19][20][21]. Although demonstrating potential on-line analytical capability for PAHs, eliminating the need for thermal desorption would simplify their measurement.…”