Determination of 22 per- and polyfluoroalkyl substances in surface water by solid-phase extraction with ultra-high performance liquid chromatography-tandem mass spectrometry

A method for the determination of 22 per- and polyfluoroalkyl substances （PFAS） by ultra-high performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS） was developed. The optimized method involves extracting particulate matter from filtered water samples with methanol， followed by combining the particulate methanol extract with the filtrate， thereby enabling efficient capture of PFAS from both dissolved and particulate phases. The samples were concentrated and purified using weak anion exchange （WAX） solid-phase extraction （SPE） columns. After nitrogen blowing， the residue was reconstituted in methanol/water （V/V=8∶2） and filtered prior to analysis by mass spectrometry， with quantification performed via the isotope internal standard method. The linear correlation coefficients （R²） of the standard curves for the 22 PFAS were all greater than 0.995， with linear ranges of 1 to 100 µg/L， detection limits of 0.2 to 0.6 ng/L， and quantification limits of 0.8 to 24 ng/L. The recovery rates of the 22 PFAS in blank water and surface water ranged from 85.3% to 139% and 76.4% to 127%， respectively， with relative standard deviations （RSD） of less than 15% （n=6）. Compared with the methods that do not involve the extraction of particulate PFAS， this method exhibited distinct advantages in the recovery rates of the 22 PFAS in surface water. These results demonstrate that the developed method is sensitive， accurate， and reliable. The incorporation of a methanol extraction step can effectively eliminate the negative bias induced by particulate adsorption， thus significantly enhancing the recovery of PFAS. This method is suitable for the quantitative determination of 22 common PFAS in surface water.