Researchers developed a novel method for volatility calibration using a Filter Inlet for Gases and Aerosols

Aerosol particles are one of the most problematic air pollutants due to their potential adverse effects on climate and human health. Organic aerosols represent a large fraction of particulate constituents on a global scale. The tendency of the organic constituents to stay in the particles or evaporate is determinant for the overall volatility of organic-containing aerosol particles. During the past years, several techniques have been developed to measure the volatility of organic aerosols, including a FIGAERO-ToF-CIMS. This method uses heat to evaporate the particle constituents into the mass spectrometer, where the aerosol composition can then be measured.

A new study led by University of Eastern Finland revealed discrepancies in volatility calibrations when using a Filter Inlet for Gases and AEROsols (FIGAERO) combined with a time-of-flight chemical ionization mass spectrometer (ToF-CIMS). A new method was developed that reduces significantly the discrepancies between volatility determinations.

The discrepancies were related to a major source of error in the most widely used calibration method, which is based on the deposition of standard compounds via syringe injection. This method led to an overestimation of saturation vapor pressures by several orders of magnitude. The new proposed method uses atomized calibration compounds that can more accurately represent the evaporation of chemical constituents from atmospheric aerosol particles. The atomizer method should from now on be used for calibrating the FIGAERO-ToF-CIMS volatility range.

Further information:

Researcher Luis Barreira, Finnish Meteorological Institute, luis.barreira@fmi.fi

Ylisirniö, A., Barreira, L. M. F., Pullinen, I., Buchholz, A., Jayne, J., Krechmer, J. E., Worsnop, D. R., Virtanen, A. and Schobesberger, S.: On the calibration of FIGAERO-ToF-CIMS: importance and impact of calibrant delivery for the particle-phase calibration, Atmos. Meas. Tech., 14(1), 355–367, https://doi.org/10.5194/amt-14-355-2021, 2021.