Vacuum Ultraviolet Photoionization Mass Spectra of Typical Organics Contained in Ambient Aerosols

ABSTRACT

This paper reports an investigation on typical organics contained in ambient aerosols with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The VUV-ATOFMS utilizes a vacuum ultraviolet krypton lamp as an ionization source. The single- and multi-constituent particles generated with typical atmospheric organics (n-eicosane, n-triacontane, 1-pentadecanol, 1-eicosanol, hexanoic acid, decanoic acid, heptadecanoic acid, oleic acid, succinic acid, pyrene, vanillin, benzoic acid, terephthalic acid, and D-galactose) are analyzed with VUV-ATOFMS. The time-of-flight mass spectra of all organic particles are obtained except hexanoic acid. The mass spectra reveal that the detection efficiencies for a certain compound contained in multi-constituent and single-constituent particles are different. These discrepancies may result from the different evaporation dynamics of aerosols in both atomization and vaporization processes. The pyrene has the strongest signal intensity in single- or multi-constituent aerosols, indicating that the VUV-ATOFMS performs well in detecting polycyclic aromatic hydrocarbons. These experimental results present a view on the VUV-photoionization mass spectra of the 14 typical organics contained in ambient aerosols.

KEYWORDS:

• ambient aerosol
• mass spectrometry
• organics
• vacuum ultraviolet photoionization

ACKNOWLEDGMENTS

This work was funded by the National Natural Science Foundation of China (No. 21207143).

Notes

F/M.W. stands for formula/molecular weight. I_single represents the signal intensity of the dominated mass peak detected in single-constituent particles and I_mixed represents that detected in multi-constituent particles. All signal intensities are normalized to that with the organic concentration at 1 mM/L and the heater temperature is 375 K. LOD stands for the limit of detection of the pure organics when the temperature is 375 K and the acquisition time is 20 s.