Real-time evaluation of terpene emissions and exposures during the use of scented wax products in residential buildings with PTR-TOF-MS

Evaluation of tetrachloroethylene (PCE) and its degradation products in human exhaled breath and indoor air in a community setting

“…The PTR-TOF-MS detected ionized VOCs (R + ) in the mass range from m/z 20-450 with a mass resolution exceeding 4000 m/∆m. Operational parameters of the PTR-TOF-MS were informed by our previous indoor air and exposure measurements with the PTR-TOF-MS [52,53] and set as follows: an inlet flow rate of 700 ml min −1 , an electric field strength to gas number density ratio (E/N) of 139 Td, an inlet temperature of 80 • C, a reaction chamber pressure of 2.2 mbar, a reaction chamber temperature of 70 • C, and a reaction chamber voltage of 600 V. Daily calibrations of the PTR-TOF-MS were performed using known standard gas mixtures (Apel-Riemer Environmental Inc., USA) containing 19 different compounds commonly measured in indoor air, including PCE, TCE, VC, toluene, 1,2dichloroethylene (1,2 DCE), acetone, benzene, isoprene, and methyl ethyl ketone. In the calibration process, the standard gas mixtures were diluted with VOC-free air (Matheson Tri-Gas Inc., USA) using a mass flow controller, achieving concentrations ranging from 2 to 50 parts per billion (ppb).…”

“…Nevertheless, the detection limits of these methods may prove insufficient for quantifying PCE concentrations in community settings [39][40][41][42]. To address these challenges, an emerging instrument can be used, which is the proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS), a highly sensitive, portable, real-time monitoring device [46][47][48][49][50][51][52][53][54]. PTR-TOF-MS can measure hundreds to thousands of VOCs, including PCE, with a low detection limit (parts per trillion (ppt) level) in real-time (1 Hz).…”