Simultaneous determination of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in Pu-erh tea by dispersive solid-phase extraction coupled with GC-MS/MS

Abstract

A novel method for the simultaneous determination of 13 PAHs and 18 PCBs residues in Pu-erh tea samples was established by combining GC-MS/MS with dispersive-solid phase extraction (d-SPE). Sample pretreatment procedure was achieved by NaCl addition and using acetone/ethyl acetate/n-hexane (50:30:20, v/v/v) extraction followed by d-SPE clean-up with strong cationic exchanger (SCX), primary secondary amine (PSA), polyvinylpolypyrrolidone (PVPP) and graphitized carbon black (GCB). The proposed method had good linearity in the range of 0.5–200 μg/L with correlation coefficients (R2 > 0.998). The detection limit ranges (LODs) were from 0.2 to 1.5 µg/kg. The spiked experiments in raw Pu-erh tea and ripened Pu-erh tea at 2.5–50 µg/kg concentrations showed satisfactory recoveries (70.2–114.7%) for all analytes with RSDs of < 10%. The validated methodology was successfully applied to 86 Pu-erh tea samples. No PCBs residue was more than LODs, and the detection frequency and concentration of PAHs in different types of Pu-erh tea varies greatly were found.