Determination of polycyclic aromatic hydrocarbons in water samples by temperature-controlled ionic liquid dispersive liquid–liquid microextraction combined with high performance liquid chromatography

Abstract

The present study describes a simple and sensitive method for the determination of polycyclic aromatic hydrocarbons (PAHs) in water samples by temperature-controlled ionic liquid dispersive liquid–liquid microextraction prior to high performance liquid chromatography with an ultraviolet detector. Three ionic liquids including 1-hexyl-3-methylimidazolium hexafluorophosphate [C₆MIM][PF₆], 1-benzyl-3-methylimidazolium hexafluorophosphate [C₇MIM][PF₆] and 1-octyl-3-methylimidazolium hexafluorophosphate [C₈MIM][PF₆] were investigated for enrichment, and the experimental results indicated that the best extraction efficiencies were achieved when [C₈MIM][PF₆] was used as the extraction solvent. Other factors affecting the extraction efficiency such as the volume of ionic liquid, heating temperature, extraction time, addition of 2-propanol, centrifugation time and ionic strength were also optimized. Under the optimal conditions, the detection limits of PAHs were in the range of 0.0005–0.88 μg L⁻¹. The intra-day and inter-day precisions of the proposed method (RSDs, n = 6) were in the range of 2.7–7.4% and 5.5–11.4%, respectively. The proposed method was applied to the analysis of real environmental water samples and good spiked recoveries in the range of 83.5–118% were achieved. All these results indicate that the proposed method is a viable alternative to existing methods and would be very useful in the future.