I'r - Memorial University of Newfoundland

this problem. Ratios ofthe two stable isotopes ofcarbon, lJC and 12C. have been
repeatedly shown characteristic ofprimary and secondary PAH sources (Freeman. 1991;
Abrajano et al., 1993; O'MaUey et al., 1994; O'MaDeyet aI., 1996). The isotopic
signatures ofindividual compounds are also found less affected by the decomposition
processes (e.g., O 'Maileyet al.. 1994; O'Malley, 1994). Therefore, to avoid the above
problems and obtain reliable results for further interpretation, the identification ofPAH
with GC-MS was followed by their quantification with GC-MS-MS and a compound
specific carbon isotope analysis (CSlA).
Identification fGC-MSJ: lndividual compoWKis were identified using a Varian
GelMS Saturn-a system. The instrument was equipped with a DB-5 capillary cohunn
(30 m x 0.25 mm l.0., 0.25 jim film thickness), with helium as the carrier gas(flow:
1mUmin). All injections were done in the splitless mode. The best chromatographic
peak resolution was achieved with the injection of0.5 ul, ofsample solution . Dried
extracts were dissolved in hexane the volume ofwhich varied from 50 to 3000 ilL
depending on concentrations ofcompounds in samples. The following temperature
regime was chosen to perform the chromatographic separation. The oven temperature
program started at SO"C for 0.1 min, and increased to 150"C at SO"CJmin. It was further
increased to 280"C at to"CJmin, where it remained for 29 .9 min. The total nm time
amounted to 45 .1 min. The injector temperature was held at 80"e for 0.1 min, with a
subsequent increase to 280"C at 180"C/min where it remained for 43 .1 min. Mass
spectral data were acquired in the electron impact mode (70eV), scanning the ion range of
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