Determination of Seven New Emerging Pollutants in Sediment Using UPLC-QTOF-MS

A method of ultra-high performance liquid chromatography coupled with quadrupole time-of-flight high resolution mass spectrometry (UPLC-QTOF-MS) was developed for the determination of seven emerging pollutants in sediment, such as salicylic acid, naproxen, ibuprofen, ketoprofen, diclofenac, clofibric acid and triclosan. Sample was extracted with ultrasonic-assisted treatment using the mixture of formic acid-acetone (1∶99,V/V) as extraction solvent, and then purified with solid-phase extraction using a mixed-mode anion exchange (MAX) cartridge, and finally detected by UPLC-QTOF-MS equipped with an electrospray ionization (ESI) source operated in negative mode. Qualitative screening was achieved according to the obtained experimental results with respect to mass accuracy, isotope distribution and relative abundance of the selected ions, i.e, a quasi-molecular ion and a fragment ion for each analyte, and retention time of the corresponding targeted compound. The positive samples, found to contain some/all of the targeted pollutants, were subject to MS/MS scan using the quasi-molecular ions of the analytes as precursor ions, thus generating fragmental ions for further confirmation. Quantification was performed with peak areas of extracted ions within a mass window of 0.05 Da. Satisfactory linearities (R²>0.99) are obtained for all analytes in the concentration range of 2-500 μg/L. Limits of detection (S/N=3) and limits of quantification (S/N=10) are in the range of 0.5-0.6 μg/kg and 1.5-2.0 μg/kg (dry weight (DW)), respectively. Recoveries are 87.8%-105.1% at three spiking levels with relative standard deviations (n=5) from 3.1% to 12.2%. The developed method was applied to the analysis of the investigated compounds in surface sediment samples collected from the Liuxi River in Guangzhou, and 4 pollutants are found with the highest concentration range of 6.51-12.26 μg/kg (DW). This method is efficient, accurate, and suitable for analysis of the seven investigated emerging pollutants in sediments.