Determination of hydroxylated metabolites of polycyclic aromatic hydrocarbons in sediment samples by combining subcritical water extraction and dispersive liquid–liquid microextraction with derivatization

A sample preparation method for the determination of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in sediment samples was developed using gas chromatography–mass spectrometry (GC–MS). Dispersive liquid–liquid microextraction (DLLME) with derivatization was performed following the subcritical water extraction (SWE) that provided which was provided by accelerated solvent extraction (ASE). Several important parameters that affected both SWE extraction and DLLME, such as the selection of organic modifier, its volume, extraction temperature, extraction pressure and extraction time were also investigated. High sensitivity of the hydroxylated PAHs derivatives by N-(tert-butyldimethylsilyl)-N-methyl-trifluoroacetamide (MTBSTFA) could be achieved with the limits of detection (LODs) ranging from 0.0139 (2-OH-nap) to 0.2334 μg kg−1 (3-OH-fluo) and the relative standard deviations (RSDs) between 2.81% (2-OH-phe) and 11.07% (1-OH-pyr). Moreover, the proposed method was compared with SWE coupled with solid phase extraction (SPE), and the results showed that ASE–DLLME was more promising with recoveries ranging from 57.63% to 91.07%. The proposed method was then applied to determine the hydroxylated metabolites of phenanthrene in contaminated sediments produced during the degradation by two PAH-degraders isolated from mangrove sediments.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We combine subcritical water extraction (SWE) with dispersive liquid–liquid microextraction (DLLME). ► Subcritical water is used as the extraction solvent for SWE and the sample solution for the following DLLME. ► Acetonitrile is used as the organic modifier for SWE and disperser solvent for DLLME in succession. ► We examine changes of OH-PAHs during the degradation by microorganism.