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TSRC, Tob. Sci. Res. Conf., 2023, 76, abstr. 50

Identification of aerosol collection related unknowns in NTA samples using GC-Orbitrap

STRIEPE L.; MOISION B.; NIP V.; JAMESON B.; JEONG L.
Juul Labs, Inc., Washington, DC, USA

As presented at the 75th TSRC, GC-MS non-targeted analysis (NTA) of JUUL ENDS aerosolized samples showed the presence of three unknown peaks ranging in concentration from 10-300 µg/g which also appeared sporadically at much lower concentration in blank measurements and were not detected in the e-liquid. This work focuses on the identification of the unknown compounds using a GC-Orbitrap instrument. The original experimental data was collected on a single quadrupole mass spectrometer with an electron impact (EI) source and could not provide unambiguous identification of the unknown compounds. Collected aerosol samples were subjected to additional analysis using an Orbitrap mass spectrometer. The Orbitrap has higher mass resolution relative to the single quadrupole mass spectrometer which allows for the molecular formula of analyzed compounds to be determined, greatly reducing the number of possible identifications. In addition, the Orbitrap used in this analysis has a chemical ionization (CI) source which produces less fragmentation relative to an EI source. The combination of high mass resolution EI and CI was successfully employed to provide provisional identities of the unknown compounds as long chain benzoates. The tentative identifications were subsequently verified as the predicted long chain benzoates by comparing the original unknown GC and MS signals to chemical standards. For the highest concentration of the three original unknown peaks, dodecyl-benzoate, Hovoglass filter pads were found to have ~2-5 µg/pad. The addition of benzoic acid to the pad extract solution was found to increase the detected concentration of dodecyl-benzoate to 21-35 µg/pad indicating a possible reaction between benzoic acid and hydrocarbons in the filter pad was responsible for the observed unknowns.