Carbon clusters in 50 nm urban air aerosol particles quantified by laser desorption–ionization aerosol mass spectrometer

• Carbon cluster quantification with laser AMS in 50 nm urban air aerosols.
• Reference material for carbon cluster measurements was prepared from 50 nm graphite.
• Detection of fullerenes in ambient samples.

A standard reference material for carbon cluster measurements by laser aerosol mass spectrometer (laser AMS) was prepared from 50 nm graphite particles suspended in toluene with assistance of high power sonication probe (72 h). The lowest measured concentration of the 50 nm graphite suspension was 3.7 pg. With the aid of the standards, carbon clusters from C14 to C19 were quantified in 50 nm urban air particles. The average amount per sample was 7.2%, ranging from 0.01 to 30.8%. The results also revealed that Laser AMS is capable of detecting fullerenes up to C100 in the 50 nm urban air particles. For comparison, qualitative ambient 50 nm particle measurements by laser AMS and by a particle soot absorption photometer (PSAP) were performed. The black carbon concentrations measured by PSAP did not correlate with the concentrations of laser AMS carbon clusters, but instead correlated strongly with the total collected mass of particles.

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