A novel calibration procedure for trace analytical measurements: application to the analysis of polybrominated diphenyl ethers by GC-MS.

The measurement of polybrominated diphenyl ethers (PBDEs) by gas chromatography-mass spectrometry (GC-MS) is highly challenging due to existence of the analytes at trace levels and the instability of the higher molecular weight PBDEs. These properties make accurate analysis especially problematic when utilising a low-resolution 'bench-top' GC-electron impact (EI) mass spectrometer. We discuss the problems associated with the analyses of PBDEs on these common GC-EI-MS systems and present a novel approach to calibration in these circumstances. We propose that this 'mixed calibration procedure' allows analyses to be performed that would not be possible using traditional calibration techniques, and that the procedure may be applied to a wide range of applications throughout analytical science.