Determination of polybrominated diphenyl ethers (PBDEs) using liquid chromatography coupled to negative ionisation atmospheric pressure photoionisation tandem mass spectrometry (LC-NI-APPI-MS/MS): validation and application to house dust

摘要

Fourteen tetra- to deca- PBDE congeners were separated on a C18 reversed phase LC column. PBDEs 47, 85, 99, 100, 153, 154, 183, 196, 197, 203, 206, 207, 208 and 209 were eluted using a gradient of methanol: water: toluene mobile phase system at a flow rate of 0.5 ml min.-1. 13C-BDE-47, 13C-BDE- 99, 13C-BDE-153, BDE-128 and 13C-BDE-209 were used as internal standards while 13C-BDE-100 was used as a syringe standard. Separated analytes were ionised using an APPI source equipped with a 10 eV krypton lamp and operated in negative ion mode. [M-Br+O]ˉ ions were monitored as precursor ions for all studied BDEs except for BDE-208, BDE-209 and 13C-BDE-209 which produced higher intensity at the [C6Br5O]ˉ ion cluster. [Br]ˉ ions were monitored as fragment ions for all target compounds. Linear five point calibration curves (r2=0.996 to 0.998) were constructed for each of the studied PBDEs in range 20-5000 pg μl-1. Method detection limits ranged from 12.3 to 29.8 pg. The method was applied for determination of PBDEs in SRM 2585 and favourable results were obtained. Unlike GC methods; no thermal degradation is encountered in the analysis of higher brominated PBDEs. In addition, this method allows the use of 13C-labelled internal standards which can compensate for any instrumental fluctuations and/or any matrix-related ion suppression or enhancement that can occur in the ion source.