Analysis of hexabromocyclododecane diastereoisomers in foods of animal origin using ultra-performance liquid chromatography-mass spectrometry and isotope dilution

A method for the detection of the α, β and γ-diastereoisomers of hexabromocyclododecane (HBCDs) in foods of animal origin, such as fish, chicken, milk, butter and so on was developed using ultra-performance liquid chromatography-electrospray ionization mass spectrometry (UPLC-ESI-MS) and isotope dilution. The HBCDs with the spiked isotopic 13C-HBCDs, the internal standards, were extracted using Soxhlet extraction, and further purified using acidic silica treatment and solid phase extraction. The separation of HBCDs was performed on Waters ACQUITY UPLCTM system with the column of BEH C18 and the gradient elution solvent of methanol-acetonitrile and water at a flow rate of 0.2 mL/min. The HBCDs were identified on the basis of the retention times and precursor ions, and quantitatively determined under the selected ion monitoring mode, m/z 640.7 for the [M–H]– ion. The limits of detection (LODs) of HBCDs ranged from 0.1 to 0.4 ng/g; and the limits of quantification (LOQs) ranged from 0.4 to 1.2 ng/g. The average recoveries ranged from 92.9% to 99.3% for the spiked levels of 0.6, 2.0 and 6.0 ng/g, with the relative standard deviations (RSDs) between 3.1% and 8.0%.