hase conditions show an increase on the order of 10 to 70 times of that
observed under reversed phase conditions (Figure 6).
The post-column addition
of dopant flow can have an effect on the overall response. This will vary from
compound to compound. As shown in Figure 7, the response of naphthalene is increased
by a factor of 7, while the response of benzo(a)pyrene is relatively unchanged.
Under normal phase conditions, 5000 pg/L fell out of the calibration range for
most PAHs, except Indeno(1,2,3,c,d) pyrene and Dibenz(a,h)anthracene. Reversed
phase conditions could be calibrated as high as 5000 pg/L (Figure 8).
Ambient
air samples were collected on high volume filters(subsequently solvent extracted,
dried to 0.2 ml) from three locations, rural, urban and a traffic tunnel. Sample
chromatogramsare shown in Figure 9, and calculated ambient concentrations are
shown in Table 2.
Conclusions
- The new PhotoSpray source provides a sensitive ionization technique for analysis
of polycyclic aromatic hydrocarbons by LC/MS/MS.
- Normal phase conditions provide an increase in sensitivity by a factor of at
least 10 and as much as 70 over reversed phase conditions.
- The APPI LC/MS/MS normal phase method provides adequate sensitivity to be useful
in the analysis of atmospheric aerosol samples for PAHs.
References
1Robb, D. B., Covey, T. R., Bruins, A. P., Anal. Chem. 2000, 72, 3653-3659.
Authors
Gary Impey, Byron Kieser, Jean-Franois Alary, Applied Biosystems/MDS SCIEX
Acknowledgements
The authors wish to thank Satoshi Irei (York University, Toronto, Canada) for
supplying PAH standards and the ambient air samples for analysis.
'"/>Source:
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