Anal. Chem. 2006, 78, 4894-4900
Analysis of Nitro-Polycyclic Aromatic Hydrocarbons in Conventional Diesel and Fischer-Tropsch Diesel Fuel Emissions Using Electron Monochromator-Mass Spectrometry Crystal D. Havey,† Robert L. McCormick,‡ R. Robert Hayes,‡ A. John Dane,† and Kent J. Voorhees*,†
Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, Colorado 80401, and National Renewable Energy Laboratory, Golden, Colorado 80401
The presence of nitro-polycyclic aromatic hydrocarbons (NPAHs) in diesel fuel emissions has been studied for a number of years predominantly because of their contribution to the overall health and environmental risks associated with these emissions. Electron monochromator-mass spectrometry (EM-MS) is a highly selective and sensitive method for detection of NPAHs in complex matrixes, such as diesel emissions. Here, EM-MS was used to compare the levels of NPAHs in fuel emissions from conventional (petroleum) diesel, ultra-low sulfur/low-aromatic content diesel, Fischer-Tropsch synthetic diesel, and conventional diesel/synthetic diesel blend. The largest quantities of NPAHs were detected in the conventional diesel fuel emissions, while the ultra-low sulfur diesel and synthetic diesel fuel demonstrated a more than 50% reduction of NPAH quantities when compared to the conventional diesel fuel emissions. The emissions from the blend of conventional diesel with 30% synthetic diesel fuel also demonstrated a more than 30% reduction of the NPAH content when compared to the conventional diesel fuel emissions. In addition, a correlation was made between the aromatic content of the different fuel types and NPAH quantities and between the nitrogen oxides emissions from the different fuel types and NPAH quantities. The EM-MS system demonstrated high selectivity and sensitivity for detection of the NPAHs in the emissions with minimal sample cleanup required. Use of alternative fuels for diesel engines, such as FischerTropsch (FT) synthetic diesel and biodiesel, has the potential to reduce petroleum consumption and thus dependence on foreign imports. As a result of alternative fuel usage, lower life-cycle greenhouse gas emissions and a reduction of certain regulated pollutant emissions, carbon monoxide, hydrocarbons, and particulate matter (PM), has been reported.1-4 Ideally, these emissions reductions will correspond to a decrease in the environmental risks and health hazards associated with diesel engine exhaust. Nitro-polycyclic aromatic hydrocarbons (NPAHs), while * To whom correspondence should be addressed. E-mail: kvoorhee@ mines.edu. Fax: 303-273-3629. † Colorado School of Mines. ‡ National Renewable Energy Laboratory.
4894 Analytical Chemistry, Vol. 78, No. 14, July 15, 2006
unregulated, are formed during incomplete combustion and are known to heavily contribute to health and environmental risks.5-10 The significant role of NPAHs to the mutagenic properties of diesel PM has been noted in particular.11,12 Here, a technique called gas chromatographic/electron monochromator-mass spectrometry (GC/EM-MS) was used to measure the NPAH content in the emissions produced from a modern production diesel engine running on conventional and FT synthetic diesel fuels. A comparison of the levels of NPAHs from the various fuel emissions allows for a toxicological evaluation of alternative fuel usage. Many studies have been conducted in the past that demonstrate the presence of NPAHs in extracts from diesel PM and diesel standard reference materials.11-24 Methods such as flame (1) Alleman, T. L.; McCormick, R. L. Fischer-Tropsch Diesel Fuels-Properties and Exhaust Emissions: A Literature Review. Proceedings of the Society of Automotive Engineers World Congress & Exhibition, Detroit, MI, March 2003; SAE, 2003; 2003-01-0763. (2) Norton, P.; Vertin, K.; Bailey, B.; Clark, N. N.; Lyons, D. W.; Goguen, S.; Eberhardt, J. Emissions from Trucks Using Fischer-Tropsch Diesel Fuel. Proceedings of the International Fall Fuels and Lubricants Meeting and Exposition, San Francisco, CA, October 1998; Alternative Fuels, 1998; SP1391. (3) United States Environmental Protection Agency. A Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions; EPA420-P-02-001, 2002. (4) McCormick, R. L.; Graboski, M. S.; Alleman, T. L.; Herring, A. M.; Tyson, K. S. Environ. Sci. Technol. 2001, 35, 1742-1747. (5) Wang, Y. Y.; Rappaport, S. M.; Sawyer, R. F.; Talcott, R. E.; Wei, E. T. Cancer Lett. 1978, 5 (1), 39-47. (6) Rosenkranz, H. S.; Mermelstein, R. Mutat. Res. 1983, 114 (3), 217-267. (7) Tokiwa, H.; Ohnishi, Y. CRC Crit. Rev. Toxicol. 1986, 17 (1), 23-60. (8) Nitrated Polycyclic Aromatic Hydrocarbons; White, C. M., Ed.; Hu ¨ thig Verlag: Heidelberg, 1985. (9) Perchermeier, M. M.; Kieferm F.; Wiebel, F. J. Toxicol. Lett. 1994, 72 (13), 53-57. (10) Sauer, J. M.; Eversole, R. R.; Lehmann, C. L.; Johnson, D. E.; Beuving, L. J. Toxicol. Lett. 1997, 90 (1), 19-27. (11) Schuetzle, D.; Riley, T. L.; Prater, T. J.; Harvey, T. M.; Hunt, D. F. Anal. Chem. 1982, 54 (2), 265-271. (12) Salmeen, I. T.; Pero, A. M.; Zator, R.; Schuetzle, D.; Riley, T. L. Environ. Sci. Technol. 1984, 18 (5), 375-382. (13) Newton, D. L.; Erickson, M. D.; Tomer, K. B.; Pellizzari, E. D.; Gentry, P.; Zweidinger, R. B. Environ. Sci. Technol. 1982, 16 (4), 206-213. (14) Paputa-Peck, M. C.; Marano, R. S.; Schuetzle, D.; Riley, T. L.; Hampton, C. V.; Prater, T. J.; Skewes, L. M.; Jensen, T. E.; Ruehle, P. H.; Bosch, L. C.; Duncan, W. P. Anal. Chem. 1983, 55 (12), 1946-1954. (15) Rondia, D., Cooke, M., Haroz, R. K., Eds. Mobile Source Emissions Including Polycyclic Organic Species; D. Reidel Publishing Co.: Dordrecht, Holland, 1983; pp 299-312. (16) Gorse, R. A., Jr.; Riley, T. L.; Ferris, F. C.; Pero, A. M.; Skewes, L. M. Environ. Sci. Technol. 1983, 17 (4), 198-202. 10.1021/ac060400q CCC: $33.50
© 2006 American Chemical Society Published on Web 06/17/2006
Table 1. Summary of Properties of Diesel Fuels by Fuel Type
fuel
typea
ULSD-LA VTCE VTCE w/30% FT FT
sulfur, mass %b
sulfur, ppmc
carbon, mass %d
hydrogen, mass %d
nitrogen, mass %d
83.04 84.35
13.46 12.2
