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

doi:10.1021/acs.analchem.8b00586

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

Mechanical Engineering

Research output: Contribution to journal › Article › peer-review

90 Scopus citations

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 (NH₄)₂SO₄-H₂SO₄ 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 language	English (US)
Pages (from-to)	11232-11239
Number of pages	8
Journal	Analytical Chemistry
Volume	90
Issue number	19
DOIs	https://doi.org/10.1021/acs.analchem.8b00586
State	Published - Oct 2 2018

Bibliographical note

Funding Information:
This work was supported by National Science Foundation (NSF) Grants CHE-1654149 (CAREER, A.P.A.) and AGS-1554936 (CAREER, C.S.D.) and University of Michigan (UM) startup funds. R.L.C. was partially supported by the Susan Lipschutz Fellowship Award. R.D.C. was supported by a Rackham Merit Fellowship Award and the Marian P. and David M. Gates UMBS Graduate Student Fellowship. S.C. and M.A.H. were supported by the Detroit Research Internship Summer Experience (D-RISE) program, by NSF Grants CHE-1654149 (A.P.A.) and CHE-1305777 (Dr. Nicolai Lehnert), other UM sources, and Cass Technical High School. Dr. Simon Clegg is thanked for helpful discussions.

Publisher Copyright:
Copyright © 2018 American Chemical Society.

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access

10.1021/acs.analchem.8b00586

OpenUrl availability

Full text

Cite this

@article{bc03d022f74146d88987ecf54f08a0bf,

title = "Direct Determination of Aerosol pH: Size-Resolved Measurements of Submicrometer and Supermicrometer Aqueous Particles",

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 (NH4)2SO4-H2SO4 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.",

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

note = "Funding Information: This work was supported by National Science Foundation (NSF) Grants CHE-1654149 (CAREER, A.P.A.) and AGS-1554936 (CAREER, C.S.D.) and University of Michigan (UM) startup funds. R.L.C. was partially supported by the Susan Lipschutz Fellowship Award. R.D.C. was supported by a Rackham Merit Fellowship Award and the Marian P. and David M. Gates UMBS Graduate Student Fellowship. S.C. and M.A.H. were supported by the Detroit Research Internship Summer Experience (D-RISE) program, by NSF Grants CHE-1654149 (A.P.A.) and CHE-1305777 (Dr. Nicolai Lehnert), other UM sources, and Cass Technical High School. Dr. Simon Clegg is thanked for helpful discussions. Publisher Copyright: Copyright {\textcopyright} 2018 American Chemical Society.",

year = "2018",

month = oct,

day = "2",

doi = "10.1021/acs.analchem.8b00586",

language = "English (US)",

volume = "90",

pages = "11232--11239",

journal = "Analytical Chemistry",

issn = "0003-2700",

number = "19",

}

TY - JOUR

T1 - Direct Determination of Aerosol pH

T2 - Size-Resolved Measurements of Submicrometer and Supermicrometer Aqueous Particles

AU - Craig, Rebecca L.

AU - Peterson, Peter K.

AU - Nandy, Lucy

AU - Lei, Ziying

AU - Hossain, Mohammed A.

AU - Camarena, Stephanie

AU - Dodson, Ryan A.

AU - Cook, Ryan D.

AU - Dutcher, Cari S.

AU - Ault, Andrew P.

N1 - Funding Information: This work was supported by National Science Foundation (NSF) Grants CHE-1654149 (CAREER, A.P.A.) and AGS-1554936 (CAREER, C.S.D.) and University of Michigan (UM) startup funds. R.L.C. was partially supported by the Susan Lipschutz Fellowship Award. R.D.C. was supported by a Rackham Merit Fellowship Award and the Marian P. and David M. Gates UMBS Graduate Student Fellowship. S.C. and M.A.H. were supported by the Detroit Research Internship Summer Experience (D-RISE) program, by NSF Grants CHE-1654149 (A.P.A.) and CHE-1305777 (Dr. Nicolai Lehnert), other UM sources, and Cass Technical High School. Dr. Simon Clegg is thanked for helpful discussions. Publisher Copyright: Copyright © 2018 American Chemical Society.

PY - 2018/10/2

Y1 - 2018/10/2

N2 - 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 (NH4)2SO4-H2SO4 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.

AB - 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 (NH4)2SO4-H2SO4 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.

UR - http://www.scopus.com/inward/record.url?scp=85053623733&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85053623733&partnerID=8YFLogxK

U2 - 10.1021/acs.analchem.8b00586

DO - 10.1021/acs.analchem.8b00586

M3 - Article

C2 - 30203960

AN - SCOPUS:85053623733

SN - 0003-2700

VL - 90

SP - 11232

EP - 11239

JO - Analytical Chemistry

JF - Analytical Chemistry

IS - 19

ER -

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

Abstract

Bibliographical note

UN SDGs

Access

OpenUrl availability

Other files and links

Fingerprint

Cite this