Determination of polychlorinated biphenyls in tea using gas chromatography-tandem mass spectrometry combined with dispersive solid phase extraction.

A gas chromatography-tandem mass spectrometry method was developed for simultaneous determination of 38 polychlorinated biphenyls (PCBs) in tea. Sample preparation was based on a dispersive solid phase extraction procedure through an extraction of target compounds. An appropriate amount of polyvinylpolypyrrolidone was directly added in tea extractions to effectively remove polyphenols, and then tea extracts were cleaned up with primary secondary amine, florisil and graphitised carbon black. The method was validated, and linearity with correlation coefficients higher than 0.99 was obtained. Satisfactory recoveries at 2, 10, 50, and 100 µg kg-1 ranged from 71% to 117% with a maximum relative standard deviation of 23%, except for PCB 81, 77, 126 and 169, of which recoveries were in the range of 32%-63%. Limits of quantitation for PCBs were 2 or 10 µg kg-1, which was set as the lowest validated and spiked level meeting the acceptable accuracy and precision.