Landfills and waste water treatment plants as sources of ... - GKSS

METHOD OPTIMISATION
Simonich et al. 2000; Bester 2004; Peck 2006). For determination of PBDEs the most
frequently used injection systems are splitless and on-column injection (Covaci et al. 2003).
Highly brominated PBDEs (octa- to decaBDE) are reported to be degraded during analytical
process. Björklund et al. (2004) described the influence of GC settings on the determination
of highly brominated PBDEs. If not selected properly, particularly column length and
injection technique may reduce the accuracy of the analytical method. Björklund et al. (2004)
tested several inlets for the analysis of PBDEs. The authors concluded that the PTV inlet is
the most suitable inlet for the analysis since the degradation of thermo-labile PBDEs is
avoided.
Due to the lack of functional groups which allows detection by other commonly applied
detectors, all musk fragrances are routinely detected by mass spectrometry (MS) (Yamagishi
et al. 1981; Bester 2004; Peck et al. 2006; Lignell et al. 2008). Nitro musks have successfully
been analysed with electron impact ionisation (EI) as the nitro groups give sufficient response
(Rimkus 1999). In the EI mode of MS, usually three mass fragments from the musk
fragrances are produced as result of a cleavage between one or more methyl groups. So far,
indications of co-elution of other substances within the mass spectra were not observed
(Bester 2009). However, musk fragrances often contain impurities (stereoisomers) which
cannot be detected properly even if advanced technologies such as tandem MS or high
resolution MS are applied (Bester 2009).
Detection of PBDEs was performed using MS either in the EI mode or the negative chemical
ionisation mode (NCI) (Eljarrat 2003). Mass spectrometry in the EI mode produces a good
selectivity through the formation of M + and the [M-2 Br] + which are used for identification
and quantification. However, EI mode has a low sensitivity for higher brominated congeners,
such as penta-, octa-, and decaBDE and is therefore not routinely applied (Covaci et al. 2003).
Benefit of the NCI mode is the enhanced sensitivity towards the Br - ions (mass-to-chargeratio,
m/z= 79, 81) and is therefore widely applied to detect PBDEs. However, the
quantification with compound-specific mass-labelled standards is not possible, since they
exhibit the same mass signal. In trace analysis it is strongly suggested to apply mass-labelled
standards for quantification. Furthermore, due to the low selectivity using two bromine ions,
coelutions of other brominated compounds such as polybrominated biphenyls and MeO-
PBDEs were reported (Stapleton 2006).
For the quantification of musk fragrances only two mass-labelled internal standards (IS) are
commercially available. Those are the deuterated musk xylene (MX D15) and the deuterated
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