Characterization of raw and ozonated oil sands process water utilizing atmospheric pressure gas chromatography time-of-flight mass spectrometry combined with solid phase microextractionun.

This work describes a novel application of atmospheric pressure gas chromatography time-of-flight mass spectrometry (APGC-TOF-MS) combined with solid-phase microextraction (SPME) for the simultaneous analysis of hydrocarbons and naphthenic acids (NAs) species in raw and ozone-treated oil sands process water (OSPW). SPME method using polydimethylsiloxane (PDMS)-coated fibers was validated using gas chromatography with flame ionization detector (GC-FID) to ensure the SPME extractions were operated appropriately. The ionization pathways of the hydrocarbon species in OSPW in the APGC source were verified by analyzing a mixture of eight polyaromatic hydrocarbons which were ionized primarily via charge transfer to produce [M+] while NAs in OSPW were found to be ionized through protonation to generate [MH+] in the wet APGC source. SPME/APGC-TOF-MS analysis demonstrated a different composition profile in OSPW #1, with 74.5% of hydrocarbon species, 23.4% of O 2 –NAs, and 2.1% of the oxidized NA species at extraction pH 2.0 compared with that obtained by UPLC-TOF-MS analysis (36.9% of O 2 –NAs, 26.8% of O 3 –NAs, 24.9% of O 4 –NAs, 9.1% of O 5 –NAs, 2.3% of O 6 –NAs). Moreover, the peak areas of the total NAs and the total peak areas of NAs + hydrocarbons measured by SPME/APGC-TOF-MS correlated excellently with the total NA concentration determined by UPLC-TOF-MS (R2 = 0.90) and the concentrations of the total acid-extractable organics determined by SPME/GC-FID (R2 = 0.98), respectively. APGC-TOF-MS integrated with the SPME techniques could extend the range of target compounds and be a promising alternative to evaluate and characterize NAs and hydrocarbon in different water types. Image 1 • SPME coupled with APGC-TOF-MS was used for analysis of hydrocarbons and NAs. • PDMS fibers preferably extracted neutral organic compounds at natural pH. • The PDMS fibers extracted hydrocarbons and some protonated NAs species at pH 2.0 • PAHs were ionized via charge transfer while NAs were ionized through protonation. • O x -NAs peak areas by SPME/APGC-TOF-MS correlated to the O x -NAs by UPLC-TOF-MS. [ABSTRACT FROM AUTHOR]