Ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography for simultaneous determination of five phenolic pollutants in edible oil

A novel ultrasound-assisted dispersive liquid-liquid microextraction using ionic liquid (UA-DLLME) was established for extraction and determination of five phenolic pollutants in edible oils by high performance liquid chromatography. NaOH was added to convert bisphenols and alkylphenols into ionic forms. A mixture of 1-Butyl3-methylimidazolium tetrafluoroborate with stronger hydrophilicity and acetonitrile were selected as the extractant. The optimum conditions found were NaOH, 100 mu L at a concentration of 0.2 mol/L; acetonitrile, 0.5 mL; [BMim][BF4], 200 mu L; ultrasound for 5 min; centrifugation for 5 min at 5000 rpm and less 11 min for the throughout sample pretreatment. The tolerance addition of edible oil sample was up to 2.0 g in the extraction system, and the matrix effect was negligible. Under the optimal experimental conditions, good linearity (r >= 0.9966) was obtained in the ranges of 1.25-275 mu g/kg for 4 analytes and 3.75-1125 mu g/kg for nonylphenol. The limits of detection and extraction efficiencies were found to be 0.360-0.550 mu g/kg, and 87.18 %-98.02 %, respectively. The intra- and inter-day RSDs were less than 5.61 % (n = 6). This method was successfully applied to the separation, enrichment and determination of five phenolic pollutants in edible oils, and the recoveries ranged from 90.0 % to 109 %.