Comparison of direct, headspace and headspace cold fiber modes in solid phase microextraction of polycyclic aromatic hydrocarbons by a new coating based on poly(3,4-ethylenedioxythiophene)/graphene oxide composite

A novel nanocomposite coating made of poly(3,4-ethylenedioxythiophene) (PEDOT) and graphene oxide was electrochemically prepared on gold wire. The prepared fiber was applied to the solid-phase microextraction (SPME) and gas chromatographic analysis of six polycyclic aromatic hydrocarbons (PAHs). Three modes of extraction i.e. direct immersion (DI), headspace (HS) and headspace cold fiber (HS-CF) in SPME were investigated. The results were compared under optimized conditions of each mode, considering the effects of the three most important parameters which are extraction temperature, extraction time and ionic strength. The comparison showed that HS-CF-SPME results in the best outcome for the extraction of PAHs from water samples. Under the optimized conditions of this mode, the calibration curves were linear within the range of 0.4–600 μg L−1 and the detection limits were between 0.05 and 0.13 μg L−1. The intra-day and inter-day relative standard deviations obtained at 10 μg L−1 (n = 5), using a single fiber, were 4.1–6.8% and 4.8–8.4%, respectively. The fiber-to-fiber repeatabilities (n = 4), expressed as the relative standard deviations (RSD%), were between 6.5% and 10.7% at a 10 μg L−1 concentration level. The method was successfully applied to the analysis of PAHs in seawater samples showing recoveries from 85% to 107%.