Determination of brominated diphenyl ethers (from mono- to hexa- congeners) in indoor dust by pressurised liquid extraction with in-cell clean-up and gas chromatography-mass spectrometry.

This study presents a selective pressurised liquid extraction (PLE) and gas chromatography-mass spectrometry/mass spectrometry method for the determination of brominated diphenyl ethers (BDEs) in indoor dust. Selective PLE consisted of the addition of Florisil mixed with the sample in order to perform an in-cell clean-up. This approach provided a cleaner and almost colourless extract, ready to be injected in the gas chromatograph. The PLE conditions were studied using an experimental design, firstly a 4 x 3 x 2 multifactor categorical design to screen sorbent, solvent and temperature and then a central composite design to optimise sorbent mass, temperature and time. Finally, the number of extraction cycles was studied. The selected conditions were 4 g of Florisil all mixed with the sample and no additional clean-up sorbent layer, 1:1 n-hexane-dichloromethane, 60% flush volume, 40 degrees C, 1,500 psi, 2-min static time and one cycle. The proposed method allowed accurate determination of BDEs, with recovery values between 82% and 101% and detection limits between 0.06 and 0.24 ng g(-1). It also has advantages over other existing methods in terms of simplicity, automation, analysis time and solvent consumption.