A modified QuEChERS method for the determination of 16 phthalate esters (PAEs) in tea samples using GC-MS/MS was developed and validated. The kinds and amounts of adsorbents were optimised, and the crude extracts were purified using primary secondary amine (PSA), graphitised carbon black (GCB) and anhydrous magnesium sulphate (MgSO4). Compared with extraction without matrix hydration, the addition of water could achieve higher extraction efficiency. The recoveries for PAEs obtained against matrix-matched standards at spiking levels of 50, 200 and 500 μg kg(-1) ranged from 84.7% to 112.7% with relative standard deviations below 20% (n = 6) for all cases. Limits of detection (0.6-36.0 μg kg(-1)) and quantitation (2.0-120.0 μg kg(-1)) were achieved using the proposed method for all PAEs. A total of 105 tea samples were found to be contaminated with PAEs.
Keywords: QuEChERS; gas chromatography-tandem mass spectrometry; phthalate esters; tea.