On the use of multicopters for sampling and analysis of volatile organic compounds in the air by adsorption/thermal desorption GC-MS

We describe a new approach for the determination of volatile organic compounds (VOCs) at precise locations in the air using active sampling on sorbent tubes outfitted to an inexpensive multicopter and analysis by thermal desorption (TD) gas chromatography-mass spectrometry (GC-MS). The aerial sampling method permits for the simultaneous collection of multiple air samples on separate TD tubes concurrently, increasing sample throughput compared to single canister sampling. Furthermore, the method is relatively inexpensive when compared to similar approaches, with overall costs below about $2000 (U.S. dollars). To demonstrate applicability, we measured VOCs at several heights near anthropogenic sources in the mid-south USA, including a municipal landfill, petroleum refinery, and a coal-fired power plant (CFPP), and within the canopy of a loblolly pine (Pinus taeda) forest. Concentrations of benzene, toluene, and xylene (BTX) were higher (p < 0.05) downwind of the refinery and CFPP compared to upwind. We observed both a unique mixture of VOCs at each site and higher concentrations of abundant VOCs downwind compared to upwind of the point sources and within versus above the forest canopy. Overall, this feasibility study demonstrates that highly maneuverable multicopters can be used to probe VOC concentrations aloft and thus have great potential to be utilized in unique sampling situations and for vertical profiling.