| Supercritical fluid extraction (SFE) of polybrominated diphenyl ethers (PBDEs) was performed on a house dust standard reference material (SRM 2585 Organic Contaminants in House Dust) using 1,1,1,2-tetrafluroethane (R134a). Three SF extraction temperatures, 110, 150 and 200ºC, were investigated for both quantification of PBDEs by independent chromatographic and mass spectrometric methods and for overall extraction efficiency. While both 150 and 200ºC provided efficient extractions for the lower congeners (<10 bromine substituents), 150ºC had a higher extraction precision. Using the extractions at 150ºC, SFE comparisons of quantification methods and dust preparation methods were evaluated. Quantification of the PBDEs was performed using GC/EI-MS/MS, GC/ECNI-MS and LC/NI-APPI/MS/MS. LC/NI-APPI/MS/MS resulted in the highest precision and permitted quantification of BDE-209, and thus it was also chosen for dust preparation comparison. SRM 2585 was prepared for SFE in three different ways (1) dry; to act as a baseline comparison sample, (2) dichloromethane wetting to swell the dust matrix, and (3) dispersed on an inorganic solid substrate (Ottawa ignition sand). Both swelling of the matrix with dichloromethane and matrix dispersing using Ottawa sand increased the precision of the SF extractions and the overall PBDE percent recovery from SRM 2585. Results concluded that while efficient SF extraction could be achieved using R134a for the lower congeners between 4 and 7 bromine substituents, the deca-brominated congener, BDE-209, could not be exhaustively extracted under the temperatures and pressures investigated in this study unless the dust was wet with dichloromethane and extracted at 200ºC. |
