Soil Analysis

Fluxes emitted from various types of soil, compounds released into soil by the roots of plants, uptake of compounds relevant to atmospheric chemistry in soil and volatile metabolites in the headspace of microbial cultures are just a few of many examples.

Particularly high mass resolution PTR-TOFMS instruments offer unmatched advantages for soil analysis, which e.g. has been impressively demonstrated in a collaboration between The Dow Chemical Company, Dow Benelux, FUGRO Consult and IONICON. At the "29^th Asilomar Conference on Mass Spectrometry*" with focus on environmental chemistry, toxicology and health a poster "Using Proton Transfer Reaction High Resolution Time-of-Flight Mass Spectrometer (PTR-HRTOF-MS) as a Specific Analyzer for Membrane Interface Probe (MIP) for Advanced Environmental Site Assessment" summarizing the results of this work has been presented.

In short, a site in the Netherlands was probed for the presences of targeted VOCs and their degradation products at various locations and depths. For the very first time a well-established Membrane Interface Probe (MIP) was coupled to a high mass resolution PTR-TOFMS instrument. This combination was chosen because common commercially available detectors for MIP are non-specific and only give information about whole compounds classes. IONICON's PTR-TOFMS on the other hand is extremely selective and even enables the separation of isobaric compounds because of the high mass resolution. Because some of the compounds of interest possessed lower proton affinities than water the SRI option was crucial for this study. Switching between reagent ions in this case meant opening the possibility of quantifying important substances such as vinyl chloride, chloroethanes and chloroethylenes.

The scientists concluded:

This new developed on-line monitoring technique was able to detect both targeted VOC and their degradation products. The data obtained with MIP-PTR-HRTOF-MS correlated well both qualitatively and quantitatively with the data obtained using conventional Purge and Trap GC/MS from the nearest monitoring well. Moreover the data delivered with such techniques will allow investigators to make decisions on how to effectively and efficiently remediate contaminates on site.

* Vyacheslav N. Fishman, Greg D. Martin, Nicolaas Van Belzen, Thorsten Steinberg, Simone Jürschik, Philipp Sulzer, 13. – 22. October 2013, Pacific Grove, CA.  

Other current publications on this topic:

• Bunge, Michael, et al. "On-line monitoring of microbial volatile metabolites by proton transfer reaction-mass spectrometry." Appl. Environ. Microbiol. 74.7 (2008): 2179-2186.

• Feilberg, Anders, Pernille Bildsoe, and Tavs Nyord. "Application of PTR-MS for measuring odorant emissions from soil application of manure slurry." Sensors 15.1 (2015): 1148-1167.