Comparison of GC-NCI MS, GC-ICP-MS, and GC-EI MS-MS for the determination of PBDEs in water samples according to the Water Framework Directive.

The Water Framework Directive (WFD) includes some polybrominated diphenyl ethers (PBDEs) in the list of priority substances that must be measured in surface waters at very low concentrations. The typical approaches applied to the determination of PBDEs in environmental samples might not meet the demanding requirements of the WFD. In this work, the instrumental capabilities of the mass-spectrometry (MS) techniques most frequently used in the determination of PBDEs, namely gas chromatography-negative-chemical-ionisation MS (GC-NCI MS) and GC-electrospray-ionisation tandem MS (EI MS-MS), are evaluated in comparison with highly sensitive GC-inductively-coupled-plasma MS (ICP-MS) for the reliable determination of PBDEs according to the WFD. Three analytical methods based on the liquid-liquid extraction of water samples and measurement of the extracts by GC-NCI MS, GC-EI MS-MS, or GC-ICP-MS are described. The priority PBDEs were quantified in different types of water sample by means of isotope-dilution mass spectrometry (IDMS) using (81)Br-labelled or (13)C-labelled PBDEs spikes, depending on the selected ionisation source. The three proposed methods met the requirements of the European legislation in terms of LOQs and expanded uncertainties. The determination method using (81)Br-labelled PBDEs and GC-ICP-MS had the highest sensitivity and the lowest instrumental limits of detection and expanded uncertainties.