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Input of an Off-Line, Comprehensive, Three-Dimensional Method (CPC×SFC/HRMS) to Quantify Polycyclic Aromatic Hydrocarbons in Vacuum Gas Oils
journal contribution
posted on 2020-04-16, 21:13 authored by Carole Reymond, Agnès Le Masle, Cyril Colas, Nadège CharonHeavy polycyclic
aromatic hydrocarbons (HPAHs) are known to cause
undesirable effects in petroleum hydrocracking processes by deactivating
the catalysts and accumulating in the downstream of reactors. Polycyclic
aromatic hydrocarbons with less than seven rings (PAHs) naturally
contained in vacuum gas oils (VGOs) act as precursors in the HPAHs
formation. However, getting a detailed quantitative characterization
of such polycyclic hydrocarbons has never been done until now, because
of the high chemical complexity of VGOs. Thus, an off-line, comprehensive,
three-dimensional methodology was required to achieve a quantitative
analysis: centrifugal partition chromatography (CPC) as the first
dimension of separation, supercritical fluid chromatography (SFC)
as the second dimension hyphenated to Fourier transform ion cyclotron
resonance mass spectrometry as the third dimension. In this study,
we demonstrated that the developed CPC method fractionated samples
according to the hydrocarbons’ alkylation degree, whereas our
SFC method provided an elution order according to their double bond
equivalent. Finally, high-resolution mass spectrometry (HRMS) brought
crucial information on the identity of analytes and proved to be essential
in the event of unresolved peaks from CPC and SFC chromatograms. To
assess the ability of the three-dimensional method for quantification
purposes, matrix effects were evaluated by spiking VGO samples with
deuterated pyrene. A strong ion suppression phenomenon was highlighted
when using only SFC/HRMS, whereas no significant matrix effect was
observed with the CPC×SFC/HRMS approach. These experiments revealed
the great potential of this innovative methodology to quantify both
PAH and HPAH in VGOs for the first time.
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Keywords
dimensionion cyclotron resonance mass spectrometrySFC chromatogramsSFC methodVacuum Gas Oils Heavy polycyclicmass spectrometrychemical complexityion suppression phenomenonvacuum gas oilsmatrix effectQuantify Polycyclic Aromatic HydrocarbonsThree-Dimensional Methodelution orderCPC methodspiking VGO samplespartition chromatographypetroleum hydrocracking processespolycyclic hydrocarbonsfluid chromatographyHPAHs formationmethodologyquantification purposesbond equivalentHRMSmatrix effects