Hollow-fibre liquid-phase microextraction: a simple and fast cleanup step used for PAHs determination in pine needles

A new, fast and simple cleanup procedure, based on hollow-fibre liquid-phase microextraction (HF-LPME) is described here, used for the determination of 13 polycyclic aromatic hydrocarbons (PAHs) in complex pine needle samples. Initially, pine needle samples were sonicated in a 20 mL aqueous solution having a 20% (v:v) acetone content and 5 mL of the sonicated liquid extract was then used for the HF-LPME cleanup step. Different experimental parameters (namely: type of organic solvent used as acceptor phase, effect and type of co-solvent, salt addition, sample agitation and sampling time) were controlled and optimized based on the response of GC-MS instrument under the SIM mode. Under the optimized experimental conditions found the typical chromatograms obtained revealed that despite the very complex matrix of pine needles the HF-LPME cleanup step greatly reduced if not eliminated the presence of interferents, resulting in chromatograms which contained very cleanly separated and readily evaluable PAH peaks. In addition, the proposed method was found to be linear in the concentration 10-2000 ngg(-1) for most target analytes and the limits of detection for a S/N=3 ranged between 0.01 and 0.95 ngg(-1) (dry weight). Furthermore, the repeatability and reproducibility were also found good. Finally, the proposed method was applied for the analysis of real pine needle samples taken for different parts of the island of Crete.