Investigation of aromatic impurities in liquefied petroleum gas by solid-phase extraction sampling coupled with gas chromatography-mass spectrometry

A dynamic solid-phase extraction system for sampling and synchronous preconcentration of aromatic impurities from liquefied petroleum gas (LPG) with graphitized carbon black (GCB) sorbents was constructed. The target aromatics (benzene, toluene, xylenes, styrene and naphthalene) were rapidly collected from LPG flow and analyzed with gas chromatography-mass spectrometry. Compared with C18 and poly (styrene-divinylbenzene) copolymer sorbents, the tandem packed GCB cartridges presented the highest extraction efficiency for capturing aromatics from LPG. The sampling efficiency, reproducibility and storage stability of aromatics on the adsorption GCB cartridge were evaluated. The quantification curves of eight aromatics in nitrogen simulative gas flow were linear in the range of 15-1000 μ g/m 3 . The developed sampling method presented good advantages of high recoveries (92.9%-109.0%), low method detection limits (1.0-6.2 μg/m 3 ), together with excellent precision (relative standard deviations:0.6%-5.8%) and accuracy (relative errors:0.8%-8.2%), respectively.