Abstract: Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography(UA-DLLME-HPLC)was developed for the determination of four typical phthalate esters (PAEs). The analyzed PAEs included dimethyl phthalate(DMP), diethyl phthalate(DEP), dibutyl phthalate(DBP)and di-n-octyl phthalate(DnOP). The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents, ultrasonic time, ionic strength and extraction time, were investigated. Enrichment factor (EF)was employed to evaluate the extraction efficiency. The conditions were finally chosen: CCl4 (40 μL)/acetonitrile (1.0 mL) as extraction/dispersion solvents; 30 g/L NaCl; ultrasound/centrifugation of 5 min. Under the optimized extraction conditions, UA-DLLME exhibited strong enrichment ability for the four PAEs. The EFs for DMP, DEP, DBP and DnOP obtained were 71, 144, 169 and 159, respectively. The limits of detection were 3.78, 1.77, 3.07 and 3.30 μg/L for DMP, DEP, DBP and DnOP, respectively. The satisfactory recoveries for three water samples at three spiked levels ranged from 82.99%-114.47%, with the relative standard deviations of 1.93%-8.31%. It is a convenient, speedy, environmentally benign method for the routine analysis of PAEs in water samples.

Key words: high performance liquid chromatography (HPLC), phthalate esters (PAEs), ultrasound-assisted (UA), water sample, dispersive liquid-liquid microextraction (DLLME)