Harmonisation of nanoparticle concentration measurements using GRIMM and TSI scanning mobility particle sizers

Manish Joshi, B. K. Sapra*, Arshad Khan, S. N. Tripathi, P. M. Shamjad, Tarun Gupta, Y. S. Mayya

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)

Abstract

Regional studies focusing on the role of atmospheric nanoparticles in climate change have gained impetus in the last decade. Several multiinstitutional studies involving measurement of nanoparticles with several kinds of instruments are on the rise. It is important to harmonize these measurements as the instruments may work on different techniques or principles and are developed by different manufacturers. Scanning mobility particle sizers (SMPS) are often used to measure size distribution of nanoparticles in the airborne phase. Two such commercially available instruments namely, GRIMM and TSISMPS have been compared for ambient and laboratory generated conditions. A stand-alone condensation particle counter (CPC) of TSI make was used as a reference for particle concentration measurements. The consistency of the results in terms of mean size and geometric standard deviation was seen to be excellent for both the SMPSs, with GRIMM always showing slightly (approximately 10 %) lower mean size. The integrated number concentration from GRIMM-SMPS was seen to be closer to stand-alone reference CPC compared to TSI-SMPS, for an ambient overnight comparison. However, a concentration- dependent response, i.e. the variations between the two instruments increasing with the concentration, was observed and possible reasons for this have been suggested. A separate experiment was performed for studying the modifying effect of diffusion dryer and sheath air dryer on the measured aerosol size spectra. A significant hygroscopic growth was noted when diffusion dryer was attached to one of the SMPS. The introduction of sheath air dryer in GRIMM-SMPS produced a significant shift towards lower mean size. These results have been compared and discussed with the recent inter-comparison results to strengthen and harmonize the measurement protocols.

Original languageEnglish
Article number1268
JournalJournal of Nanoparticle Research
Volume14
Issue number12
DOIs
Publication statusPublished - Dec 2012
Externally publishedYes

Keywords

  • GRIMM
  • Harmonisation
  • Nanoparticles
  • SMPS
  • Sheath air dryer
  • TSI

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