Determination of 16 Polycyclic Aromatic Hydrocarbons in Tea by Simultaneous Dispersive Solid-Phase Extraction and Liquid–Liquid Extraction Coupled with gas Chromatography–Tandem Mass Spectrometry

Abstract

An anti-contamination method for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in tea was developed using gas chromatography–tandem mass spectrometry. In this study, three transitions for each PAHs were monitored at multi-reaction monitoring (MRM) mode and pseudo-MRM mode to improve the reliability of the developed method. The PAHs were extracted using acetonitrile and then cleaned up by simultaneous dispersive solid-phase extraction (D-SPE) and liquid–liquid extraction (LLE). A mixture of adsorbents that contain primary–secondary amine, octadecylsilane and florisil was applied for the D-SPE cleanup. The solvent used for LLE was n-hexane with a 1:2 (v/v) ratio of acetonitrile extracts and n-hexane. Loss of PAHs occurred during sample preparation because of incomplete extraction of PAHs from the acetonitrile extracts into n-hexane with the LLE treatment. Isotopic surrogate standards were used to calibrate for the loss of PAHs during sample preparation. For the 16 PAHs, linear calibrations with coefficients R 2 ≥ 0.99 were obtained. The limits of quantifications of the 16 PAHs were <3 μg kg−1. The recovery rates of samples spiked with 10, 50 and 200 μg kg−1 of analytes varied from 77 to 116 %, with relative standard deviations of <13 %. The developed method was used to determine the PAHs in 46 tea samples.