Determination of Triclosan and Methyl-Triclosan in Vegetables and Fruits by GC-MS/MS

A method for determination of triclosan (TCS) and methy-triclosan (MTCS) in vegetables (taking tomato and cucumber as analytical objects) and fruits (taking orange and apple as analytical objects) by GC-MS/MS was proposed, hoping to help the study on pollution of food by these pollutants, and also to apply this method to the safety inspections on quality of agricultural products. The selected samples should be peeled, stripped, sliced and homogenized separately and priliminarily and the homogenate be kept at -22℃. A portion of the homogenate (5.00 g) was extracted ultrasonically twice in succession with ethyl acetate (10 mL for each extraction) for 10 min, and then centrifuged for 10 min. The extracts from 2 extractions were collected, combined and evaporated to near-dryness by N₂-blowing. 100 μL of derivatizing mixed solution of BSTFA-TMCS with the volume ratio of 99:1 were added to the residue to carry out the derivatization at 60℃ for 40 min. After which the solution was evaporated again to near dryness by N₂-blowing. The residue was dissolved with 1.0 mL of ethyl acetate, and the solution obtained was used for GC-MS/MS analysis. Chromatographic separation was carried out by passing the solution through the capillary column of DB-17MS (30 m×0.25 mm,0.25 μm), under programmed temperature from 150℃ to 290℃. MS/MS determination was accomplished under the condition of EI and MRM mode. As determined by experiment, the molecular ion and product ion found for derivate of TCS were m/z 362, 347 and m/z 360, 345, and for MTCS were m/z 304, 254. Linearity ranges of the standard curves of derivate of TCS and of MTCS were found same between 0.4-20.0 μg·L^-1, and values of their detection limits (3S/N) were found in the range of 4-6 ng·kg^-1. Recovery was tested by standard addition method, giving values of recovery in the range of 91.5%-107% (for derivate of TCS), and in the range of 94.7%-111% (for MTCS).