Measurement of spatial and temporal variation in volatile hazardous air pollutants in Tacoma, Washington, using a mobile membrane introduction mass spectrometry (MIMS) system

Abstract

The objective of this study was to use membrane introduction mass spectrometry (MIMS), implemented on a mobile platform, in order to provide real-time, fine-scale, temporally and spatially resolved measurements of several hazardous air pollutants. This work is important because there is now substantial evidence that fine-scale spatial and temporal variations of air pollutant concentrations are important determinants of exposure to air pollution and adverse health outcomes. The study took place in Tacoma, WA during periods of impaired air quality in the winter and summer of 2008 and 2009. Levels of fine particles were higher in winter compared to summer, and were spatially uniform across the study area. Concentrations of vapor phase pollutants measured by membrane introduction mass spectrometry (MIMS), notably benzene and toluene, had relatively uniform spatial distributions at night, but exhibited substantial spatial variation during the day-daytime levels were up to 3-fold higher at traffic-impacted locations compared to a reference site. Although no direct side-by-side comparison was made between the MIMS system and traditional fixed site monitors, the MIMS system typically reported higher concentrations of specific VOCs, particularly benzene, ethylbenzene and naphthalene, compared to annual average concentrations obtained from SUMA canisters and gas chromatographic analysis at the fixed sites.

A Field-Portable Membrane Introduction Mass Spectrometer for Real-time Quantitation and Spatial Mapping of Atmospheric and Aqueous Contaminants

“…Figure 5 shows a 5 h continuous time series collected while driving and parked in a discrete pattern (termed a 'Rosette') at strategic locations in and around a SAGD demonstration facility, similar to the methodology employed in other work by our group [17]. Subpanel a illustrates the data obtained for benzene, toluene, and ethylbenzene (+xylene).…”

“…Many of these analytical techniques, such as membrane introduction mass spectrometry (MIMS), can provide continuous monitoring time series data that resolve multiple analyte concentrations simultaneously [16,17,[19][20][21][22][23][24]. When operated on a mobile platform, these instruments can track transient concentration excursions in both spatial and temporal domains that may be missed by grab sampling strategies [24].…”

“…The advent of portable chemical sensing technology has enabled a new framework for environmental monitoring, where it is possible to take high precision, high accuracy chemical measurements to the field [10][11][12][13][14][15][16][17][18]. Many of these analytical techniques, such as membrane introduction mass spectrometry (MIMS), can provide continuous monitoring time series data that resolve multiple analyte concentrations simultaneously [16,17,[19][20][21][22][23][24].…”

“…Our research has involved the development of a portable MIMS system for the continuous analysis of VOCs and SVOCs in both atmospheric and aqueous samples that greatly improves upon our early work in this area [16,17,20]. In general, MIMS systems allow continuous sampling of VOC/SVOC analytes as they diffuse through a semiselective membrane, whereupon simultaneous quantification of multiple copermeating molecules occurs by mass spectrometry [20,25,26].…”

The Effect of the Earth’s and Stray Magnetic Fields on Mobile Mass Spectrometer Systems

“…T he popularity of field portable mass spectrometry is growing as many of the technical hurdles of bringing laboratory equipment into the field are overcome [1][2][3]. On-site analysis requires that instrumentation can be transported conveniently, powered remotely, be free of self-contamination, and can be serviced in adverse conditions.…”