Determination of PBDEs in human breast adipose tissues by gas chromatography coupled with triple quadrupole mass spectrometry.

The potential of gas chromatography/tandem mass spectrometry with a triple quadrupole analyzer for determination of 12 polybrominated diphenyl ethers in human breast tissues has been investigated. After extraction with hexane, two purification procedures-automated normal-phase high-performance liquid chromatography and solid-phase extraction-were assayed. Both electron impact ionization, in selected reaction monitoring mode, and negative chemical ionization, in selected ion recording mode, were tested for the optimum determination of analytes. Isotopically labeled standards were added before extraction as surrogates: [13C]BDE47, [13C]BDE99 and [13C]BDE153 for electron impact ionization, and p,p'-DDE-d (8) for negative chemical ionization. The method was validated in terms of accuracy, precision, limits of detection and limits of quantification, using human breast tissue spiked at three levels in the range 1-50 ng/g (5-250 ng/g for BDE209). The analytical approach using solid-phase extraction cleanup followed by gas chromatography/mass spectrometry (negative chemical ionization ) led to lower detection limits (0.006-2 ng/g) and allowed the determination of the most problematic congener, BDE209, whose poor sensitivity made difficult its determination at low residue levels. Special attention was given to the confirmation of the compounds detected in samples in order to avoid reporting false positives. Two tandem mass spectrometry transitions or three m/z ions were selected for each analyte when using electron impact ionization or negative chemical ionization modes, respectively. In both cases, the transition to ion intensity ratio was used as a confirmation parameter. The method developed was applied to the analysis of real human samples. Several brominated diphenyl ethers (congeners 47, 100, 99, 154, 153, 183 and 209) were detected in the range 0.08-0.23 ng/g.