Rapid Determination of Perfluoroalkyl and Polyfluoroalkyl Substances (PFASs) in Vegetables by on-Line Solid-Phase Extraction (SPE) with Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry (UHPLC-MS/MS)

Per- and poly-fluoroalkyl substances (PFASs) are a class of synthetic organic chemicals that include thousands of compounds. Analytical methods for PFASs in vegetables are limited. In this study, a rapid and sensitive method using on-line solid phase extraction (SPE) coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed and validated for the simultaneous determination of 21 PFASs in vegetables. The extraction solvent volume and procedure were optimized to achieve good efficiencies (>93%) using the lowest quantity of solvent. The injection volume, elution condition of the online SPE system, and the mobile phases of the UHPLC-MS/MS system were also optimized to improve the sensitivity, peak symmetry, and resolution. The method detection limits of the 21 targeted PFAS were from 0.001 to 0.008 ng/g and the linearity was from 0.1 to 1000 pg/mL using an injection volume of 5 mL. The validation results indicate that this method is precise, accurate, and robust. Moreover, this method is high throughput (similar to 15 min per sample); thus, suitable for analyzing a large number of vegetable samples in a short time interval. In addition, the developed method was successfully applied to analyze vegetables. The results show that the total PFAS concentrations were the highest in lettuce, followed by potatoes and tomatoes, and the lowest in broccoli. Different profiles of PFASs were observed among the vegetable species.