Optimization of congener-specific analysis of 40 polybrominated diphenyl ethers by gas chromatography/mass...

The analysis by gas chromatography coupled with mass spectrometry (GC/MS) of 40 different congeners of polybrominated diphenyl ethers (PBDEs) containing 1-7 bromine atoms is described. Two different MS approaches were used, negative chemical ionization (NCI-MS) and electron ionization (EI-MS). Operating parameters such as electron energy and source temperature were optimized in order to obtain the maximum sensitivity in the EI-MS study. For NCI-MS analyses, the effects of the moderating gas (methane or ammonia), source temperature and system pressure were studied. The quality parameters of the two approaches tested were compared. NCI-MS gave detection limits between 30 fg and 1.72 pg, whereas EI-MS gave detection limits between 0.53 and 32.09 pg. The main advantage of EI-MS is that it provides better structural information. Moreover, the use of EI-MS allowed the use of an isotope dilution method for quantification, making the analysis more reliable at trace levels.