TY - JOUR

T1 - Supercritical fluid chromatography for the analysis of oxygenated polycyclic aromatic compounds in unconventional oils

AU - Lübeck, Josephine S.

AU - Malmquist, Linus M.V.

AU - Christensen, Jan H.

PY - 2019/3/29

Y1 - 2019/3/29

N2 - Unconventional oil feeds can be rich in oxygenated organic compounds that will negatively affect the fuel properties if they are not removed during refining. In this study, supercritical fluid chromatography (SFC) was utilised for the combined analysis of polycyclic aromatic hydrocarbons (PAHs) and oxygenated polycyclic aromatic compounds (OPACs). One objective was to chromatographically separate PAHs from OPACs; another to reach a high peak capacity, improved peak shapes and high signal-to-noise ratios (S/N) for OPACs. These objectives were set to establish a non-target analysis method for oxygenated compounds in unconventional oils by SFC hyphenated to a UV detector and a quadrupole time-of-flight mass spectrometer (QTOF-MS) with negative electrospray ionisation (ESI − ). Highest peak capacities were observed with a 2-picolylamine column with methanol as modifier, however, a better resolution and S/N were obtained with ethanol and 0.1% formic acid. The elution order for OPACs on all columns followed mainly the polarity of the analytes: furans < aldehydes ≤ ketones < phenols ≤ carboxylic acids. Best separation between PAHs and OPACs was achieved with the ethylene-bridged silica column. The optimised SFC-UV-ESI − -QTOF-MS method was tested on a coal tar middle distillate and a pyrolysis oil where a number of homologous series (e.g. hydroxy-naphthalenes and –benzaldehydes) was tentatively identified.

AB - Unconventional oil feeds can be rich in oxygenated organic compounds that will negatively affect the fuel properties if they are not removed during refining. In this study, supercritical fluid chromatography (SFC) was utilised for the combined analysis of polycyclic aromatic hydrocarbons (PAHs) and oxygenated polycyclic aromatic compounds (OPACs). One objective was to chromatographically separate PAHs from OPACs; another to reach a high peak capacity, improved peak shapes and high signal-to-noise ratios (S/N) for OPACs. These objectives were set to establish a non-target analysis method for oxygenated compounds in unconventional oils by SFC hyphenated to a UV detector and a quadrupole time-of-flight mass spectrometer (QTOF-MS) with negative electrospray ionisation (ESI − ). Highest peak capacities were observed with a 2-picolylamine column with methanol as modifier, however, a better resolution and S/N were obtained with ethanol and 0.1% formic acid. The elution order for OPACs on all columns followed mainly the polarity of the analytes: furans < aldehydes ≤ ketones < phenols ≤ carboxylic acids. Best separation between PAHs and OPACs was achieved with the ethylene-bridged silica column. The optimised SFC-UV-ESI − -QTOF-MS method was tested on a coal tar middle distillate and a pyrolysis oil where a number of homologous series (e.g. hydroxy-naphthalenes and –benzaldehydes) was tentatively identified.

KW - Column screening

KW - Homologous series

KW - Method optimisation

KW - Modifier additives

KW - Oxygenated polycyclic aromatic hydrocarbon

KW - PAH

KW - Supercritical fluid chromatography

KW - Unconventional oils

UR - http://www.scopus.com/inward/record.url?scp=85059572887&partnerID=8YFLogxK

U2 - 10.1016/j.chroma.2018.12.056

DO - 10.1016/j.chroma.2018.12.056

M3 - Journal article

C2 - 30635173

AN - SCOPUS:85059572887

VL - 1589

SP - 162

EP - 172

JO - Journal of Chromatography

JF - Journal of Chromatography

SN - 0301-4770

ER -