Project at a Glance

Title: Development of laser diagnostics methods for PAH: phase 1; development of laser desorption laser photoionization mass spectrometry method for the screening of polycyclic aromatic hydrocarbons in soots and fly ash

Principal Investigator / Author(s): Kelly, P B.

Contractor: UC Davis

Contract Number: A932-099

Research Program Area: Emissions Monitoring & Control, Health & Exposure

Topic Areas: Stationary Sources, Toxic Air Contaminants


A Laser Desorption Laser Photoionization Mass Spectrometry (LDLPMS) technique has been developed for the direct screening of polycyclic aromatic hydrocarbons (PAHs) in as-received soot and fly-ash samples. The method employs pulsed IR desorption from the surface of particulate matter collected on air sampling filters, followed by UV laser multiphoton ionization of the desorbed molecules. The ions thus formed are mass-analyzed in a custom-built time of flight mass spectrometer. Photoionization of PAH standards at 266 nm procedures intense parent molecular ion peaks with little or no fragmentation, allowing identification via molecular weight determination. The application of the method to the detection of PAHs in rice soot samples is demonstrated. The level of detection for PAHs is estimated to be 10-20 ng/sample, which is well within the low resolution target detection limit for ARB Method 429.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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