Evaluation of comprehensive two-dimensional gas chromatography time-of-flight-mass spectrometry for the analysis of polycyclic aromatic hydrocarbons in sediments

This study evaluates the feasibility of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC x GC-ToF MS) for the determination of the 15 + 1 EU PAHs in sediments. Experimental variables affecting the injection, chromatographic separation and analytical detection of the analytes have systematically been optimised. Under finally proposed conditions, a satisfactory resolution among critical pairs/groups of PAHs, including benz[a]anthracene, cyclopenta[cd]pyrene and chrysene, the three benzofluoranthene isomers, indeno[1,2.3-cd]pyrene from dibenzi[a,h]anthracene (DahA), and DahA from dibenz[a,c]anthracene, has been achieved using DB-5 x BPX-50 as column combination with a run time of 1 h. The feasibility of the method for the analysis of real-life samples has been demonstrated by accurate determination of relevant target PAHs in the certified harbour sediment BCR-535 (deviations among certified concentration values and those calculated using the proposed method lower than 3%); and by successful application to sediments sampled from a relevant protected area located in the South of Spain. The low methodological limits of detection (LODs) obtained for most of the targeted PAHs (in the 5.7-60 mu g/kg range, as calculated for real samples) guarantied accurate quantification of the target compounds at the low levels expected in these types of pristine matrices. The strong retention experienced by the heaviest dibenzopyrene isomers included in the study resulted in relatively high LODs for these analytes: nevertheless, these compounds were detected at concentration levels above the corresponding LOD in some of the analysed sediments. In addition, the enhanced identification power provided by GC x GC-ToF MS for the identification of nontarget analytes allowed the tentative identification of a group of polynuclear aromatic thiophenes in some of the test samples. Finally, the potential of the use of normalised bubble plots for the fast screening of the potential PAH sources has been demonstrated. (C) 2012 Elsevier B.V. All rights reserved.