Gas chromatography-mass spectrometry determination of polybrominated

Gas chromatography coupled to mass spectrometry in negative chemical ionization (NCI) 11 mode has been applied to the quantification and reliable identification of polybrominated 12 diphenyl ethers (PBDEs) in animal and vegetable samples from aquaculture activities. 13 Matrices analyzed included fish fillet, fish feed, fish oil and linseed oil, which their fat content 14 ranged from 5 to 100%. Solid phase extraction (using Florisil and silica cartridges) and 15 normal-phase high performance liquid chromatography were tested for an efficient clean-up 16 in order to obtain sample extracts free of interfering compounds. Combining sulphuric acid 17 digestion and solid-phase extraction with Florisil led to the highest efficiency in the 18 elimination of interferences from the extracts. The sample procedure developed, together with 19 the application of GC-(NCI)MS for measurement, led to the satisfactory determination of 20 PBDEs at μg Kg -1 levels in complex aquaculture matrices with high lipid content. The use of 21 a short and thin film-thickness fused-silica capillary column allowed to determine the 22 problematic BDE 209 with satisfactory results. Three m/z ions were acquired for each analyte, 23 which ensured a reliable identification of compounds detected in samples. 24