Determination of polycyclic aromatic hydrocarbons in soil samples using flotation-assisted homogeneous liquid-liquid microextraction

In this study, flotation-assisted homogeneous liquid-liquid microextraction (FA-HLLME) was developed as a fast, simple, and efficient method for extraction of four polycyclic aromatic hydrocarbons (PAHs) in soil samples followed by gas chromatography-flame ionization detector (GC-FID) analysis. A special home-made extraction cell was designed to facilitate collection of the low-density extraction solvent without a need for centrifugation. In this method, PAHs were extracted from soil samples into methanol and water (1:1, v/v) using ultrasound in two steps followed by filtration as a clean-up step. The filtrate was added into the home-made extraction cell contained mixture of 1.0 mL methanol (homogenous solvent) and 150.0 mu L toluene (extraction solvent). Using N-2 flotation, the dispersed extraction solvent was transferred to the surface of the mixture and was collected by means of a micro-syringe. Then, 2 mu L of the collected organic solvent was injected into the GC-FID for subsequent analysis. Under optimal conditions, linearity of the method was in the range of 40-1000 mu g kg(-1) soil (dry weight). The relative standard deviations in real samples varied from 5.9 to 15.2% (n=4).The proposed method was successfully applied to analyze the target PAHs in soil samples, and satisfactory results were obtained. (C) 2012 Elsevier B.V. All rights reserved.