A multi-dimensional high performance liquid chromatographic method for fingerprinting polycyclic aromatic hydrocarbons and their alkyl-homologs in the heavy gas oil fraction of Alaskan North Slope crude.
We report an offline multi-dimensional high performance liquid chromatography (HPLC) technique for the group separation and analysis of PAHs in a heavy gas oil fraction (boiling range 287-481 degrees C). Waxes present in the heavy gas oil fraction were precipitated using cold acetone at -20 degrees C. Recovery studies showed that the extract contained 93% (+/-1%; n=3) of the PAHs that were originally present while the wax residue contained only 6% (+/-0.5%; n=3). PAHs present in the extract were fractionated, based on number of rings, into five fractions using a semi-preparative silica column (normal-phase HPLC). These fractions were analyzed using reverse-phase HPLC (RP-HPLC) coupled to a diode array detector (DAD). The method separated alkyl and un-substituted PAHs on two reverse-phase columns in series using an acetonitrile/water mobile phase. UV spectra of the chromatographic peaks were used to differentiate among PAH groups. Further characterization of PAHs within a given group to determine the substituent alkyl carbon number used retention time matching with a suite of alkyl-PAH standards. Naphthalene, dibenzothiophene, phenanthrene and fluorene and their C1-C4 alkyl isomers were quantified. The concentrations of these compounds obtained using the current method were compared with that of a GC-MS analysis obtained from an independent oil chemistry laboratory.
Saravanabhavan
Gurusankar
G
Department of Chemistry and School of Environmental Studies, Queens University, Kingston, ON, Canada.
Helferty
Anjali
A
Hodson
Peter V
PV
Brown
R Stephen
RS
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D010578:Petroleum / Q000032:analysis*; D011084:Polycyclic Aromatic Hydrocarbons / Q000302:isolation & purification*
D010578:Petroleum; D011084:Polycyclic Aromatic Hydrocarbons