Dispersive liquid-liquid microextraction-gas chromatography-mass spectrometric determination of polycylic aromatic hydrocarbons in water

Abstract

In this work, a sample preparation method based on dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) was developed for the extraction of polycyclic aromatic hydrocarbons (PAHs), namely phenanthrene and fluoranthene from water sample. In this method, a mixture of carbon tetrachloride, CCl4 (extraction solvent) and acetone (disperser solvent) was injected using a syringe into 5 mL water sample to form emulsion where the PAHs were extracted into the fine droplets of extraction solvent. The solution was then centrifuged for 3 min at 3000 rpm and the fine droplets were sedimented at the bottom of centrifuge tube. Sedimented phase (1 ?L) was injected into the GC-MS for separation and determination of PAHs. The effects of various extraction parameters namely extraction solvent type, disperser solvent type, volume of extraction solvent, and volume of disperser solvent were investigated. The optimized conditions for DLLME of selected PAHs were carbon tetrachloride as extraction solvent, 60 ?L of extraction solvent (CCl4), acetone as disperser solvent and 1 mL of disperser solvent (acetone). The correlation coefficient (r2) of the calibration curve for phenanthrene and fluoranthene were 0.9993 and 0.9973, respectively. The limits of detection (LODs) obtained for phenanthrene and fluoranthene were 0.0008 ?g/mL and 0.0006 ?g/mL, respectively. The proposed method proved to be reproducible with relative standard deviations (RSDs) of 10.69 % and 9.72 % for phenanthrene and fluoranthene, respectively. The analyte recoveries were 100.5 – 107.8 %. The concentration of was 0.02-0.15 ?g/mL. It was found that phenanthrene and fluoranthene were present in lake water sample at concentrations of 3.47×10-3 and 2.69×10-3 ?g/mL. The DLLME method combined with GC-MS proved to be an efficient method and was applied successfully for the determination of PAHs from water sample