Direct Determination of Aerosol pH: Size-Resolved Measurements of Submicrometer and Supermicrometer Aqueous Particles

Rebecca L. Craig, Peter K. Peterson, Lucy Nandy, Ziying Lei, Mohammed A. Hossain, Stephanie Camarena, Ryan A. Dodson, Ryan D. Cook, Cari S Dutcher, Andrew P. Ault

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Measuring the acidity of atmospheric aerosols is critical, as many key multiphase chemical reactions involving aerosols are highly pH-dependent. These reactions impact processes, such as secondary organic aerosol (SOA) formation, that impact climate and health. However, determining the pH of atmospheric particles, which have minute volumes (10 -23 -10 -18 L), is an analytical challenge due to the nonconservative nature of the hydronium ion, particularly as most chemical aerosol measurements are made offline or under vacuum, where water can be lost and acid-base equilibria shifted. Because of these challenges, there have been no direct methods to probe atmospheric aerosol acidity, and pH has typically been determined by proxy/indirect methods, such as ion balance, or thermodynamic models. Herein, we present a novel and facile method for direct measurement of size-resolved aerosol acidity from pH 0 to 4.5 using quantitative colorimetric image processing of cellular phone images of (NH 4 ) 2 SO 4 -H 2 SO 4 aqueous aerosol particles impacted onto pH-indicator paper. A trend of increasing aerosol acidity with decreasing particle size was observed that is consistent with spectroscopic measurements of individual particle pH. These results indicate the potential for direct measurements of size-resolved atmospheric aerosol acidity, which is needed to improve fundamental understanding of pH-dependent atmospheric processes, such as SOA formation.

Original languageEnglish (US)
Pages (from-to)11232-11239
Number of pages8
JournalAnalytical chemistry
Volume90
Issue number19
DOIs
StatePublished - Oct 2 2018

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Aerosols
Particles (particulate matter)
Acidity
Atmospheric aerosols
Chemical reactions
Image processing
Particle size
Health
Thermodynamics
Vacuum
Ions
Water

PubMed: MeSH publication types

  • Journal Article
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, Non-U.S. Gov't

Cite this

Craig, R. L., Peterson, P. K., Nandy, L., Lei, Z., Hossain, M. A., Camarena, S., ... Ault, A. P. (2018). Direct Determination of Aerosol pH: Size-Resolved Measurements of Submicrometer and Supermicrometer Aqueous Particles. Analytical chemistry, 90(19), 11232-11239. https://doi.org/10.1021/acs.analchem.8b00586

Direct Determination of Aerosol pH : Size-Resolved Measurements of Submicrometer and Supermicrometer Aqueous Particles. / Craig, Rebecca L.; Peterson, Peter K.; Nandy, Lucy; Lei, Ziying; Hossain, Mohammed A.; Camarena, Stephanie; Dodson, Ryan A.; Cook, Ryan D.; Dutcher, Cari S; Ault, Andrew P.

In: Analytical chemistry, Vol. 90, No. 19, 02.10.2018, p. 11232-11239.

Research output: Contribution to journalArticle

Craig, RL, Peterson, PK, Nandy, L, Lei, Z, Hossain, MA, Camarena, S, Dodson, RA, Cook, RD, Dutcher, CS & Ault, AP 2018, 'Direct Determination of Aerosol pH: Size-Resolved Measurements of Submicrometer and Supermicrometer Aqueous Particles', Analytical chemistry, vol. 90, no. 19, pp. 11232-11239. https://doi.org/10.1021/acs.analchem.8b00586
Craig, Rebecca L. ; Peterson, Peter K. ; Nandy, Lucy ; Lei, Ziying ; Hossain, Mohammed A. ; Camarena, Stephanie ; Dodson, Ryan A. ; Cook, Ryan D. ; Dutcher, Cari S ; Ault, Andrew P. / Direct Determination of Aerosol pH : Size-Resolved Measurements of Submicrometer and Supermicrometer Aqueous Particles. In: Analytical chemistry. 2018 ; Vol. 90, No. 19. pp. 11232-11239.
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