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Anal Chem

Title:		Investigation of the utility of laser-secondary neutral mass spectrometry for the detection of polyaromatic hydrocarbons in individual atmospheric aerosol particles
Author(s):		Tyler BJ; Dambach S; Galla S; Peterson RE; Arlinghaus HF;
Address:		"Department of Chemical Engineering, University of the West Indies, St. Augustine, Trinidad and Tobago"
Journal Title:		Anal Chem
Year:		2012
Volume:		20111209
Issue:		1
Page Number:		76 - 82
DOI:		10.1021/ac2008338
ISSN/ISBN:		1520-6882 (Electronic) 0003-2700 (Linking)
Abstract:		"The distribution of polyaromatic hydrocarbons (PAHs) in ambient aerosol particles is of importance to both human health and climate forcing. Although time-of-flight secondary ion mass spectrometry (ToF-SIMS) has proven useful for studying the distribution of organic compounds in individual aerosol particles, it is difficult to detect PAHs at relevant concentrations in individual aerosol particles because of their low ion yield. In this study, we explore the potential of using laser secondary neutral mass spectrometry (Laser-SNMS) to study three PAHs: pyrene, anthracene, and naphthalene. Because of the high volatility of PAHs, a cryostage was required for the analysis to prevent sublimation of the molecules into the vacuum chamber. We studied two laser systems, a 157 nm excimer laser, which is capable of single-photon ionization of the PAHs, and a 193 nm laser, which requires multiphoton ionization. Under optimized conditions for laser power density and primary ion pulse length, 193 nm postionization resulted in a 2-50-fold increase in ion yield over ToF-SIMS. Using the 157 nm laser, the yield was increased by more than 3 orders of magnitude for all 3 PAHs studied. The single-photon postionization process proved superior in terms of both yield enhancement and reduced fragmentation. By using the optimized 157 nm laser system and a cryostage, we were able to detect PAHs on the surface of 2 mum diameter ambient aerosol particles"
Keywords:		*Aerosols Atmosphere Lasers Mass Spectrometry/*methods Polycyclic Compounds/*analysis;
Notes:		"MedlineTyler, Bonnie J Dambach, Steffen Galla, Sebastian Peterson, Richard E Arlinghaus, Heinrich F eng EB-002027/EB/NIBIB NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't 2011/08/10 Anal Chem. 2012 Jan 3; 84(1):76-82. doi: 10.1021/ac2008338. Epub 2011 Dec 9"