Input of an off-line comprehensive three-dimensional method (CPCxSFC/HRMS) to quantify polycyclic aromatic hydrocarbons in vacuum gas oils

Carole Reymond (1) , Agnès Le Masle (1) , Cyril Colas (2, 3) , Nadège Charon (1)

1 IFPEN - IFP Energies nouvelles
2 ICOA - Institut de Chimie Organique et Analytique
3 CBM - Centre de biophysique moléculaire

Heavy polycyclic aromatic hydrocarbons (HPAH) are known to cause undesirable effects in petroleum hydrocracking processes by deactivating the catalysts and accumulating themselves in the downstream of reactors. Polycyclic aromatic hydrocarbons with less than 7 rings (PAH) naturally contained in vacuum gas oils (VGO) act as precursors in the HPAH formation. However, getting a detailed quantitative characterisation of such polycyclic hydrocarbons has never been done until now because of the high chemical complexity of VGO. 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 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 CPC×SFC/HRMS approach. These experiments revealed the high potential of this innovative methodology to quantify both PAH and HPAH in VGO for the first time.

Mots clés: Hydrocarbon; Alcohols; Chromatography; Solvents; Aromatic Compounds

Domaines: Chimie

Carole Reymond, Agnès Le Masle, Cyril Colas, Nadège Charon. Input of an off-line comprehensive three-dimensional method (CPCxSFC/HRMS) to quantify polycyclic aromatic hydrocarbons in vacuum gas oils. Analytical Chemistry, 2020, 92 (9), pp.6684-6692. ⟨10.1021/acs.analchem.0c00605⟩. ⟨hal-02872094⟩