Application of solid phase extraction and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry for fast analysis of polycyclic aromatic hydrocarbons in vegetable oils

A fast and simple solid-phase extraction (SPE) method followed by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC-TOFMS) has been developed for analysis of 15 + 1 carcinogenic polycyclic aromatic hydrocarbons (PAHs) in vegetable oils. Of three critically assessed sample preparation approaches - (i) gel permeation chromatography (GPC), (ii) GPC followed by silica based SPE, and (iii) SPE employing PAHs-dedicated molecularly imprinted polymers (MIPs), the latter one was selected as the best option. Recoveries of the overall analytical procedure ranged from 70 to 99%, with repeatabilities in the range of 2-11%. Limits of quantitation (LOQs) ranging for individual PAHs from 0.1 to 0.3 μg kg−1, were fairly below the maximum level 2 μg kg−1 established for the PAHs representative, benzo[a]pyrene (BaP), by EU Legislation for this commodity. Within the mini-survey in which the new method was employed for examination of 35 samples of various kinds of vegetable oils collected at the Czech market, the highest PAH4 levels, i.e. the sum of BaP, benz[a]anthracene (BaA), benzo[b]fluoranthene (BbFA) and chrysene (CHR) were found in sea buckthorn (708 μg kg−1) followed by rapeseed oil (99.8 μg kg−1). Altogether 8 samples from 35 examined vegetable oils exceeded the maximum limit 2 μg kg−1 for BaP and 10 samples exceeded 10 μg kg−1 set for PAH4 which is fixed by Commission Regulation (EU) no 835/2011 for oils.