Direct quantification of PAHs in biomass burning aerosols by desorption electrospray ionization mass spectrometry

Desorption electrospray ionization mass spectrometry (DESI-MS) technique was applied to the quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) in biomass burning aerosols. Experimental conditions were optimized to enhance the detection efficiencies of PAHs. DESI-MS signal intensities showed good linear responses to the amount of PAHs in a dynamic range of four orders of magnitude and the detection limit is about 1 pg/mm2. Mass concentrations of three-, four-, five-, six-ring PAHs in laboratory-made rice straw burning aerosols were directly measured by DESI-MS without any sample pretreatment. The results agree well with the parallel measurement by traditional GC–MS. DESI phenomenon was also observed for other compounds in biomass burning aerosols such as sugars, inorganic and organic acids. Potential applications of DESI-MS to the rapid analysis of multiple components in aerosol samples were discussed.