Determination of Polycyclic Aromatic Hydrocarbons in Environmental Water Samples by Microwave-Assisted Headspace Solid-Phase Microextraction

Microwave-assisted headspace solid-phase microextraction (MA-HS-SPME) with a polydimethylsiloxane/divinylbenzene (PDMS/DVB) and PDMS fibers were applied as a single step before determination of polycyclic aromatic hydrocarbon (PAH) concentrations in water using gas chromatography-mass spectrometry (GC-MS). PDMS/DVB was found better in performance and was chosen for the rest of the investigations. Dissolved organic matter (DOM) was found to not effect PAH analysis significantly. This study (MA-HS-SPME) presents the first finding in the literature that total (both freely dissolved and DOM-associated) PAH concentration was determined. To optimize the extraction efficiency of PAHs by MA-HS-SPME, influence of various parameters, including fibers, temperature, duration of thermal desorption, microwave irradiation power and duration, and the temperature of the circulating cooling water system, was studied. Under optimal operating conditions, good linearity of a calibration curve was observed over the studied concentration range for 16 PAHs (0.1-5 mu g/L) in aqueous solution. PAH detection limit varied from 26.8 to 128 ng/L. A protocol was then proposed for estimating field binding constant between PAH and DOM through using our proposed MA-HS-SPME method and traditional SPME technique (freely dissolved PAH concentration determined). The proposed method was demonstrated applicable to environmental water samples, especially contaminated aquatic environment samples.