Commonly, analytical methods measuring brominated flame retardants (BFRs) of different chemical polarities in human serum are labor consuming and tedious. Our study used acidified diatomaceous earth as solid-phase extraction (SPE) adsorbent and defatting material to simultaneously determine the most abundant BFRs and their metabolites with different polarities in human serum samples. The analytes include three types of commercial BFRs, tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD) isomers, and polybrominated biphenyl ethers (PBDEs), and dominant hydroxylated BDE (OH-PBDE) and methoxylated BDE (MeO-PBDE) metabolites of PBDEs. The sample eluents were sequentially analyzed for PBDEs and MeO-BDEs on online gel permeation chromatography/gas chromatography-electron capture-negative ionization mass spectrometry (online GPC GC-ECNI-MS) and for TBBPA, HBCD, and OH-BDEs on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Method recoveries were 67-134% with a relative standard deviation (RSD) of less than 20%. Method detection limits (MDLs) were 0.30-4.20 pg/mL fresh weight (f.w.) for all analytes, except for BDE-209 of 16 pg/mL f.w. The methodology was also applied in a pilot study, which analyzed ten real samples from healthy donors in China, and the majority of target analytes were detected with a detection rate of more than 80%. To our knowledge, it is the first time for us in effectively determining BFRs of most types in one aliquot of human serum samples. This new analytical method is more specific, sensitive, accurate, and time saving for routine biomonitoring of these BFRs and for integrated assessment of health risk of BFR exposure.
Keywords: Acidified diatomaceous earth; BFRs; Human serum; LC-MS/MS; Online GPC-ECNI-MS; TBBPA.