Identification and trace level determination of brominated flame retardants by liquid chromatography/quadrupole linear ion trap mass spectrometry

We describe the development of instrumental methodology for the simultaneous determination of hexabromocyclododecane (HBCD) diastereoisomers and tetrabromobisphenol A (TBBPA) and its derivatives by liquid chromatography/quadrupole linear ion trap mass spectrometry (LC-QqLIT-MS). Two different experiments were developed, optimized and compared. The first is based on a selected reaction monitoring (SRM) method in which the two most abundant transitions were selected for each analyte, as well as for the internal standards. In the second, the ion trap was used for the storage and subsequent fragmentation of precursor ions, obtaining an enhanced product ion (EPI) experiment. Both methods were validated by measuring quality parameters such as linearity, sensitivity, reproducibility and repeatability. Limits of detection (LODs) were in the range of 0.1-1.8 pg and 0.01-0.5 pg for SRM and EPI experiments, respectively, being lower than those published for the LC/QqQ-MS methods. Thus, LC-QqLIT-MS, used for quantification and confirmation, proved to be a powerful and very sensitive analytical tool.