This work describes the applicability of magnetic ionic liquids (MILs) in the analytical determination of a group of heavy polycyclic aromatic hydrocarbons. Three different MILs, namely, benzyltrioctylammonium bromotrichloroferrate (III) (MIL A), methoxybenzyltrioctylammonium bromotrichloroferrate (III) (MIL B), and 1,12-di(3-benzylbenzimidazolium) dodecane bis[(trifluoromethyl)sulfonyl)]imide bromotrichloroferrate (III) (MIL C), were designed to exhibit hydrophobic properties, and their performance examined in a microextraction method for hydrophobic analytes. The magnet-assisted approach with these MILs was performed in combination with high performance liquid chromatography and fluorescence detection. The study of the extraction performance showed that MIL A was the most suitable solvent for the extraction of polycyclic aromatic hydrocarbons and under optimum conditions the fast extraction step required ∼20 μL of MIL A for 10 mL of aqueous sample, 24 mmol L−1 NaOH, high ionic strength content of NaCl (25% (w/v)), 500 μL of acetone as dispersive solvent, and 5 min of vortex. The desorption step required the aid of an external magnetic field with a strong NdFeB magnet (the separation requires few seconds), two back-extraction steps for polycyclic aromatic hydrocarbons retained in the MIL droplet with n-hexane, evaporation and reconstitution with acetonitrile. The overall method presented limits of detection down to 5 ng L−1, relative recoveries ranging from 91.5 to 119%, and inter-day reproducibility values (expressed as relative standard derivation) lower than 16.4% for a spiked level of 0.4 μg L−1 (n = 9). The method was also applied for the analysis of real samples, including tap water, wastewater, and tea infusion.
Bibliographical noteFunding Information:
MJT-R thanks the Agencia Canaria de Investigación, Innovación y Sociedad de la Información (ACIISI) , co-funded by the European Social Fund , for her FPI PhD fellowship. VP acknowledges funding from the Spanish Ministry of Economy and Competitiveness (MINECO) projects ref. MAT2013–43101–R and MAT2014-57465-R . JHA and VP also thank funding from the Fundación CajaCanarias , project ref. SPDs-Agua05. J.L.A. acknowledges funding from the Chemical Measurement and Imaging Program at the National Science Foundation (grant number CHE-1413199 ).
© 2016 Elsevier B.V.
- High-performance liquid chromatography
- Ionic liquids
- Magnetic ionic liquids
- Magnetic-assisted microextraction
- Polycyclic aromatic hydrocarbons