Coupling the extraction efficiency of imidazolium-based ionic liquid aggregates with solid-phase microextraction-gas chromatography-mass spectrometry. Application to polycyclic aromatic hydrocarbons in a certified reference sediment

Three ionic liquid (IL)-based aggregates, 1-hexadecyl-3-methylimidazolium bromide (HDMIm-Br), 1-hexadecyl-3-butylimidazolium bromide (HDBIm-Br), and 1,3-didodecylimidazolium bromide (DDDDIm-Br) have been applied to the development of a quantitative solid-phase microextraction (SPME)-gas chromatography (GC)-mass spectrometry (MS) method. A sensitivity factor (SF) is defined and introduced for the first time to quantitatively compare the efficiency of the IL-based aggregates by SPME-GC-MS and to evaluate the partitioning strength of several polycyclic aromatic hydrocarbons (PAHs) to the three IL-aggregates. The ILs HDBIm-Br and HDMIm-Br have been used successfully to extract seven PAHs from the certified reference sediment BCR-535 using focused microwave-assisted extraction followed by SPME-GC-MS. Average recoveries for six of the seven certified PAHs were 84.6% for HDMIm-Br and 101% for HDBIm-Br, with relative standard deviation values (RSDs) lower than 19%. The overall extraction method requires short extraction times (around 7 min for the microwave step) and avoids the use of organic solvents.