Sample preparation procedure for the determination of polycyclic aromatic hydrocarbons in petroleum vacuum residue and bitumen

Abstract

This paper describes a novel method of sample preparation for the determination of trace concentrations of polycyclic aromatic hydrocarbons (PAHs) in high-boiling petroleum products. Limits of quantitation of the investigated PAHs in materials of this type range from tens of nanograms per kilogram to <20 μg/kg. The studies revealed that in order to separate most of interferences from the analytes without a significant loss of PAHs, it is necessary to use size exclusion chromatography as the first step of sample preparation, followed by adsorption using normal-phase liquid chromatography. The use of orthogonal separation procedure described in the paper allows the isolation of only a group of unsubstituted and substituted aromatic hydrocarbons with a specific range of molar mass. The lower the required limit of quantitation of PAHs, the larger is the scale of preparative liquid chromatography in both steps of sample preparation needed. The use of internal standard allows quantitative results to be corrected for the degree of recovery of PAHs during the sample preparation step. Final determination can be carried out using HPLC-FLD, GC-MS, or HPLC-UV–VIS/DAD. The last technique provides a degree of identification through the acquired UV–VIS spectra.FigureChromatograms obtained using UV-DAD detection with wavelength programming (A) and fluorimetric detection (B) for the separation of 18 PAH standards ((A) and (B)) and the fraction containing PAHs from road asphalt 50/70 prepared according to the procedure described in this work (C). Peak designation: 1 naphthalene, 2 acenaphthylene, 3 acenaphthene, 4 fluorene, 5 phenanthrene, 6 anthracene, 7 fluoranthene, 8 pyrene, 9 benzo[a]anthracene, 10 chrysene, 11 benzo[b]fluoranthene, 12 benzo[k]fluoranthene, 13 benzo[a]pyrene, 14 dibenzo[a,h]anthracene, 15 indeno[1,2,3-cd]pyrene, 16 benzo[ghi]perylene, 17 benzo[j]fluoranthene, 18 benzo[e]pyrene,19 highly polar components of road asphalt 50/70 eluted during backflush. BF backflush point

Normal-phase liquid chromatography retention behavior of polycyclic aromatic hydrocarbon and their methyl-substituted derivatives on an aminopropyl stationary phase

“…RPLC separations on a polymeric octadecylsilane (C 18 ) stationary phase [4] and GC [5] on a 50% phenyl methylpolysiloxane (MPS) phase or 50% liquid crystalline dimethylpolysiloxane stationary phase has been shown to provide excellent separations of isomeric PAHs. NPLC is often used as a low resolution fractionation technique to isolate PAHs for further characterization by RPLC and/or GC [6–19]. …”

Rapid quick, easy, cheap, effective, rugged, and safe extraction with novel phospholipid cleanup: A streamlined ultra high performance liquid chromatography with ultraviolet detection approach for screening polycyclic aromatic hydrocarbons in avian blood cells and plasma

“…PAH extraction from biological matrices has historically been difficult due to the high lipid and protein content of such samples [22][23][24]. Recent method development studies have used a variety of techniques for PAH extraction including accelerated solvent extraction, liquid-phase separation, SPE, gel permeation chromatography, and ultrasonic extraction [1, 16,[24][25][26][27][28][29][30][31]. In a study of vegetable oils, Fromberg et al utilized gel permeation chromatography as an extraction method, though it was necessary to remove lipids and other compounds before analysis using a silica SPE column [28]; this step added valuable time to the preparation process.…”

Application of normal-phase high-performance liquid chromatography followed by gas chromatography for analytics of diesel fuel additives

“…1—backflush point at 12 min, the additive peak collected in backflush) from polar main components of cleaning additives, i.e., 2-ethylhexanol, which makes quantitative analysis by gas chromatography much easier. The use of pyrene as a marker determining eluent backflush point (EBF) results from the nature of group separation in normal HPLC, where pyrene is commonly employed as an indicator of the end of elution of tria-romatic compounds [14–16]. This enables removal of most of hydrocarbon components of the diesel fuel matrix from the collected fraction.…”