Determination of Pentachlorophenol on the Surface of Wooden Chopping Board by Gas Chromatography-Tandem Mass Spectrometry

A method was established for the determination of pentachlorophenol in wooden chopping board by gas chromatography-tandem mass spectrometry (GC-MS/MS). The samples were prepared by the surface sampling method and the nine-point layout method. 2,4,6-tribromophenol internal standard solution of 10.0 mg·L^-1 (50 μL) was added into the sample of 2.00 g, and a mixture of ethyl acetate and n-hexane at volume ratio of 1∶9 (10 mL) was used as the extractant. After purification by SLC solid phase extraction column, the eluent was blown to 1.0 mL with nitrogen, and a mixture of acetic anhydride and pyridine at volume ratio of 1∶1 was used for derivatization. After derivatization, the sample was separated on Agilent J&W DB-5MS quartz capillary column by column temperature program. The mode of multireaction monitoring (MRM) was adopted in MS/MS, and internal standard method was used for quantitative analysis. The results showed that linear relationship between peak area ratio of pentachlorophenol derivative and 2,4,6-tribromophenol derivative and mass concentration of pentachlorophenol was found in the range of 25-800 μg·L^-1, with detection limit (3S/N) of 0.003 mg·kg^-1. Test for recovery was made by standard addition method, giving results in the range of 86.0%-96.0%, and RSDs (n=5) of the determined values less than 5.0%. This method was used to carry out special food safety risk monitoring on 80 samples of wooden chopping board, and the hidden risk of high residues of pentachlorophenol (up to 384.350 mg·kg^-1) in non-shaped packaging wooden chopping boards was discovered, which provided risk early warning for relevant departments.