Halogenated phenolic compound determination in plasma and serum by solid phase extraction, dansylation derivatization and liquid chromatography–positive electrospray ionization–tandem quadrupole mass spectrometry

A robust, sensitive and accurate method was developed for the simultaneous determination in plasma and serum of suite a halogenated phenolic compounds (HPCs) for which several are known to persist in the environment and analytically pure standards are available. Namely, 14 congeners of hydroxylated polybrominated diphenyl ethers (OH-PBDEs), six congeners of hydroxylated polychlorinated biphenyls (OH-PCBs), pentachlorophenol, pentabromophenol and the flame retardant tetrabromobisphenol A (TBBPA). Solid phase extraction (SPE) enriched the target compounds and cleaned up the samples as a result of efficient adsorption on a strong anion-exchange solid phase SPE cartridge (Oasis MAX). After final clean-up the HPCs were derivatized with dansyl chloride and analyzed by liquid chromatography–tandem mass spectrometry with electrospray ionization in positive mode (ESI(+)). Chromatographic separation was achieved on a Luna PFP(2) column (2 mm × 100 mm, 3 μm particle size) with mobile phases of water and acetonitrile (both containing 0.1% formic acid). The addition of the dansyl moiety to the HPCs greatly improved analyte sensitivity as the electrospray ionization efficiency was enhanced. Instrument limits of detection (ILODs) for LC–ESI(+)–MS/MS analysis of the HPCs were in the range of 0.01–0.07 ng/mL and the method limits of quantification (MLOQs) were in the range of 0.02–0.15 ng/g. Recovery efficiencies of the suite of HPCs ranged from 64% to 118% with relative standard deviations from 2% to 12% from fortified bovine serum samples. The method was successfully applied for HPC determination in representative polar bear and snapping turtle plasma samples.