Sampsa Martikainen This email address is being protected from spambots. You need JavaScript enabled to view it.1, Sanna Saarikoski2, Paxton Juuti1, Hilkka Timonen2, Jorma Keskinen1, Panu Karjalainen1

1 Aerosol Physics Laboratory, Tampere University, Tampere, Finland
2 Atmospheric Composition Research, Finnish Meteorological Institute, Helsinki, Finland

Received: November 20, 2020
Revised: February 15, 2021
Accepted: February 16, 2021

 Copyright The Author's institutions. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited. 

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Martikainen, S., Saarikoski, S., Juuti, P., Timonen, H., Keskinen, J., Karjalainen, P. (2021). Soot Particle Agglomeration Inlet (SPAI) for Enabling Online Chemical Composition Measurement of Nanoparticles with the Aerosol Mass Spectrometer. Aerosol Air Qual. Res. 21, 200638.


  • A concept for measuring nanoparticle chemical composition online.
  • Designed as an inlet to the Soot Particle Aerosol Mass Spectrometer (SP-AMS).
  • Laboratory tests with synthetic silver nanoparticles as test aerosol.
  • Up to 35-fold enhancement in the silver nanoparticle detection with the SP-AMS.


Nanoparticles are a topic of interest because of their effects on human health and the climate, but the current options for evaluating their chemical composition—one of the key properties that determine the mechanisms of these effects—remain very limited and often require long collection times. For example, the Soot Particle Aerosol Mass Spectrometer (SP-AMS) is an instrument that measures the chemical properties of particles in real time, but sampling loss fixes its lower particle size limit at 50 nm, thus excluding nanoparticles. Hence, we developed the Soot Particle Agglomeration Inlet (SPAI), an addition to the SP-AMS that enables it to detect and analyze nanoparticles by attaching them to the surfaces of artificially generated soot particles. We characterized and optimized the soot generation and the soot–nanoparticle agglomeration via laboratory testing and then assessed the SPAI’s performance using silver nanoparticles as the test aerosol. The SPAI increased the SP-AMS’s capability to detect the silver nanoparticles by 35 times, demonstrating its potential in resolving issues related to analyzing the chemical composition of nanoparticles, either as an enhancement of the SP-AMS or as an addition to other sample pretreatment systems.

Keywords: Aerosol characterization, Nanoparticle, Chemical composition

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