Optimization of two different dispersive liquid-liquid microextraction methods followed by gas chromatography-mass spectrometry determination for polycyclic aromatic hydrocarbons (PAHs) analysis in water

Novel sample preparation methods termed up-and-down shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME) and water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction (WLSEME) coupled with gas chromatography-mass spectrometry (GC-MS) have been developed for the analysis of 11 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. For UDSA-DLLME, an up-and-down shaker-assisted emulsification was employed. Extraction was complete in 3 min. Only 14 mu L of 1-heptanol was required, without a dispersive solvent. Under the optimum conditions, the linear range was 0.08-100 mu g L-1, and the LODs were in the range 0.022-0.060 mu g L-1. The enrichment factors (EFs) ranged from 392 to 766. Relative recoveries were between 84% and 113% for river, lake, and field water. In WLSEME, 9 mu L of 1-nonanol as extraction solvent and 240 mu L of 1 mg L-1 Triton X-100 as surfactant were mixed in a microsyringe to form a cloudy emulsified solution, which was then injected into the samples. Compared with other surfactant-assisted emulsion methods, WLSEME uses much less surfactant. The linear range was 0.08-100 mu g L-1, and the LODs were 0.022-0.13 mu g L-1. The EFs ranged from 388 to 649. The relative recoveries were 86 - 114% for all three water specimens. (C) 2013 Elsevier B.V. All rights reserved.