Emulsification liquid-liquid microextraction based on deep eutectic solvent: An extraction method for the determination of benzene, toluene, ethylbenzene and seven polycyclic aromatic hydrocarbons from water samples

In this study, for the first time, a simple, inexpensive and sensitive method named emulsification liquid-liquid microextraction based on deep eutectic solvent (ELLME-DES) was used for the extraction of benzene, toluene, ethylbenzene (BTE) and seven polycyclic aromatic hydrocarbons (PAHs) from water samples. In a typical experiment, 100 μL of DES (as water-miscible extraction solvent) was added to 1.5 mL of sample solution containing target analytes. A homogeneous solution was formed immediately. Injection of 100 μL of THF (as emulsifier agent) into homogeneous solution provided a turbid state. After extraction, phase separation (aqueous phase/DES rich phase) was performed by centrifugation. DES rich phase was withdrawn by a micro-syringe and submitted to isocratic reverse-phase HPLC with UV detection. Under optimum conditions obtained by response surface methodology (RSM) and desirability function (DF), the calibration graphs were linear in the concentration range from 10 to 200 μg/L for benzene, 10-400 μg/L for toluene, 1-400 μg/L for ethylbenzene, biphenyl, chrysene and fluorene, and 0.1-400 μg/L for anthracene, benzo[a]pyrene, phenanthrene and pyrene. The coefficients of determination (r2) and limits of detection were 0.9924-0.9997 and 0.02-6.8 μg/L, respectively. This procedure was successfully applied to the determination of target analytes in spiked water samples. The relative mean recoveries ranged from 93.1 to 103.3%.