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Environ Int 32, 2006, 575 585.pdf


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S. Rayne et al. / Environment International 32 (2006) 575–585

2. Experimental methods
2.1. Photolyses
Separate 1.3 × 10− 9 M solutions of BDE153 in HPLC grade acetonitrile
(Caledon Laboratories), Milli-Q grade distilled water, and unfiltered seawater
(taken at 1m depth about 5m from shoreline at the Institute of Ocean Sciences
[Patricia Bay, Sidney, BC, Canada] on June 11, 2002) were prepared by
dissolving 2.5 ng in 3mL of solvent. These concentrations are 20-fold lower than
the reported water solubility limit of 2.6 × 10− 8 M for BDE153 (Wania and
Dugani, 2003).
Solutions were not degassed prior to, or during, photolysis and were
expected to contain an equilibrium quantity of dissolved oxygen. Samples were
irradiated in 3mL quartz cuvettes open to the atmosphere and placed 5cm from a
6W 302nm 38cm × 8.1cm × 6.4cm UV lamp (Ultra-Violet Products UVM-57)
mounted horizontally in a secure and consistent placement. With the exception
of the 0- to 60-min duration trials taken at 5-min intervals, all samples were run
in duplicate at each time interval. To compare the relative effects of the 302nm
UV lamp versus solar irradiation, duplicate 1.3 × 10− 9 M solutions of BDE153 in
acetonitrile in a 3mL quartz cuvette were also exposed to solar irradiation for
periods of 0, 3, 6, 9, 12, and 15min between 1:30 and 3:00pm on June 11, 2002,
a clear day with an air temperature of 22 °C. For each solvent system, the 0-min
photolyses were allowed to sit at room temperature (about 20°C) for 60min
prior to workup, thereby acting as thermal blanks for the photochemical studies.
In all cases, no loss of starting material was observed for these 60-min duration
thermal controls. In addition, no potential thermal or photochemical products
were observed in the starting solutions or the thermal controls.

2.2. Sample workup
Following photolysis, all samples were spiked with the following
commercial internal standard solution prior to workup: 25μL of MBDE-MXA
from Wellington Laboratories containing 5μg/mL each of 13C-labelled 2,2′,4,4′tetrabromodiphenyl ether (13C-BDE47), 2,2′,4,4′,5-pentabromodiphenyl ether
(13C-BDE99), and 2,2′,4,4′,6,6′-hexabromodiphenyl ether (13C-BDE155). The
100μL aliquots removed for analysis from aqueous samples were filtered
through a Pasteur pipette containing a 0.2 cm layer of MgSO4 over a 0.2 cm layer
of hexane-rinsed Kimwipes. The MgSO4 was subsequently rinsed with
3 × 250μL of 1 : 1 pesticide grade distilled-in-glass toluene / dichloromethane
for solvent exchange. Both the 100 μL direct aliquots from photolyses in
acetonitrile and the 750μL solvent exchanged extracts in toluene:dichloromethane from the aqueous photolyses were reduced in volume to about 25μL
under gentle heating and a stream of nitrogen, and subsequently transferred to an
amber glass microvial.
For all samples in microvials awaiting analysis, 10μL each of the following
commercial recovery standards were added: EO-5101 from Cambridge Isotope
Laboratories containing 100ng/mL of 13C-labelled 3,3′,4,4′-tetrabromodiphenyl
ether (13C-BDE77) and 150 ng/mL of 13C-labelled 3,3′,4,4′,5-pentabromodiphenyl ether (13C-BDE126); MBDE-MXB from Wellington Laboratories
containing 5μg/mL each of 13C-labelled 2,4,4′-tribromodiphenyl ether (13CBDE28), 2,2′,4,4′,5,6′-hexabromodiphenyl ether (13 C-BDE154), and
2,2′,3,4,4′,5′,6-heptabromodiphenyl ether (13C-BDE171); and 10 μL of a
50μg/mL solution of 13C-labelled 2,3,7,8-tetrabromodibenzo[1,4]dioxin (13C2,3,7,8-TeBDD). Microvials were capped immediately after addition of the
recovery standard and stored at − 20°C in preparation for analysis by highresolution gas chromatography and mass spectrometry (HRGC–HRMS).

2.3. Instrumental analyses
Analyses were performed by HRGC–HRMS using a Micromass Ultima
mass spectrometer equipped with an Agilent 6890 gas chromatograph. For all
analyses, the HRGC was operated in the splitless injection mode, and the
splitless injector purge valve was activated 2min after sample injection. The
volume injected was 1μL of sample plus 0.5μL of air. The HRMS was
operated under positive EI conditions with the filament in the trap
stabilization mode at 600μA, an electron energy of 35eV, and perfluorokerosene used as the calibrant.

577

2.3.1. PBDE SIM analyses
Analyses for PBDE photoproducts and unreacted starting material were
performed using a standard 15m DB5-HT column (0.25mm I.D. × 0.1 μm film
thickness) from J&W Scientific with ultra-high purity helium as the carrier gas.
The instrument operated at 10,000× resolution, data were acquired in the
selected ion monitoring (SIM) mode, and the two most abundant isotopic
peaks were monitored for each molecular ion cluster. The temperature program
used under constant pressure (42 kPa) was as follows: hold at 100 °C for 1min;
2°C/min to 140 °C; 4°C/min to 220 °C; 8°C/min to 330 °C; and hold 1.2min.
The splitless injector port, direct HRGC–HRMS interface, and the HRMS ion
source were maintained at 300 °C, 260 °C, and 300 °C, respectively.
Analytical standards were available for identification and quantitation of the
following possible PBDE photoproducts: 2,2′,4,5′-tetrabromodiphenyl ether
(BDE49); 2,2′,4,4′-tetrabromodiphenyl ether (BDE47); 2,3′,4,4′-tetrabromodiphenyl ether (BDE66); 3,3′,4,4′-tetrabromodiphenyl ether (BDE77); 2,2′,4,5,5′pentabromodiphenyl ether (BDE101); and 2,2′,4,4′,5-pentabromodiphenyl
ether (BDE99). A total suite of 41 individual mono- through deca-brominated
diphenyl ether analytical standards was available, but only congeners
representing potential primary or secondary photohydrodebromination products
of BDE153 are listed above.
Analytes were identified only when the HRGC–HRMS data satisfied all of
the following quality assurance/quality control (QA/QC) criteria: (1) two
isotopes of the analyte were detected by their exact masses with the HRMS
operating at 10,000× resolution during the entire chromatographic run; (2) the
retention time of the analyte peak was within 3 s of the predicted time obtained
from analysis of authentic compounds in the calibration standards (where
available); (3) the maxima for both characteristic isotopic peaks of an analyte
coincided within 2s; (4) the observed isotope ratio of the two ions monitored per
analyte were within 15% of the theoretical isotopic ratio; and (5) the signal-tonoise ratio resulting from the peak response of the two corresponding ions was
≥3 for proper quantification of the analyte. Analyte concentrations were
calculated by the internal standard isotope-dilution method using mean relative
response factors (RRFs) determined from calibration standard runs made before
and after each batch of samples was analyzed. Recoveries of individual internal
standards were between 40% and 120% for all analyses. Concentrations of
analytes were corrected for percent recoveries of the internal standards.
2.3.2. PBDF SIM analyses
Analyses for PBDF photoproducts were performed using the HRGC–HRMS
system. A 15m DB5-HT column (0.25mm I.D. × 0.10μm film thickness) from
J&W Scientific with ultra-high purity helium as the carrier gas was used. The
instrument operated at 10,000× resolution, data were acquired in the SIM mode,
and the two most abundant isotopic peaks were monitored for each molecular ion
cluster. The temperature program used under constant pressure (36kPa) was as
follows: hold at 100°C for 2min; 20°C/min to 200°C; and 4°C/min to 314°C. The
splitless injector port, direct HRGC–HRMS interface, and the HRMS ion source
were maintained at 282°C, 260°C, and 300°C, respectively. An analytical standard
was available for 2,3,7,8-tetrabromodibenzofuran (2,3,7,8-TeBDF). The QA/QC
criteria for identification and quantitation of PBDFs analyzed via this method were
equivalent to the criteria outlined above for PBDE SIM analyses.
2.3.3. Brominated 2-hydroxybiphenyl full scan and SIM analyses
Full scan analyses to look for brominated 2-hydroxybiphenyl photoproducts
not having an available standard were performed using a HRGC–LRMS. The
low-resolution mass spectrometer (LRMS) used was a Voyager–Finnigan
(ThermoFinnigan, USA) instrument. A standard 30 m DB5 column (0.25mm I.
D. × 0.25μm film thickness) from J&W Scientific was used with ultra-high
purity helium as the carrier gas. The HRGC–LRMS was operated in the positive
ion mode and at unit resolution over the range from m/z 50 to 725. The GC
temperature program used under constant flow conditions (1 mL/min) was as
follows: hold at 100°C for 2min; 4°C/min to 300°C; and hold for 3min. The
splitless injector port, direct HRGC–LRMS interface, and the LRMS ion source
were maintained at 300 °C, 270°C, and 250°C, respectively.
The extract from the 1-min duration 302 nm irradiation of BDE153 in
acetonitrile revealed three unknown photoproducts with relative molecular ion
cluster areas of 1.1 : 1.8 : 1.0 that were tentatively assigned as tetrabrominated 2hydroxybiphenyls. This compound class assignment was based on analyte elution
times that were significantly greater (about 10min) than the corresponding