Development of Advanced Field 

Measurement Techniques for 

Sampling Atmospheric Particles

Prepared by 

C. E. Kolb

Aerodyne Research, Inc.

Billerica, MA 01821-3976

Prepared for 

Aerosol Metrology for Climate Workshop 

National Institute of Standards and Technology

Gaithersburg, MD 20899-8300

March 14-15, 2011
Number 

Density

Surface 

Area

Mass PM2.5 < 15μg/m3

PM10 < 40μg/m3

“remote continental”

Pandis and Seinfeld, 1998

Ultrafine Fine Coarse

Ambient Aerosol Size 

Distribution

Aerosols can be complex

Variations in:

Size

Shape

Number

Chemical composition
Chronic and Acute Impacts on Human Health

- PM2.5 NAAQS

Climate Impacts from Scattering and Absorbing 

Solar Radiation and Cloud Nucleation

- Direct Radiative Forcing

- Indirect Radiative Forcing (Clouds)

- Precipitation (Clouds)

Impacts on Natural and Agricultural Ecosystems

- Acid Deposition

- Solar Radiation Diminution (PAR)

- Temperature and Precipitation Effects

Key Atmospheric Fine PM 

Impacts
`

Inorganic vs. organic aerosol PM 

components

Inorganics Organics

Few components (SO4

2-

, NO3

-

, NH4

+...) 1,000’s-10,000’s of compounds (more?)

Formed by well-established chemistry Formation chemistry uncertain

Well-characterized properties Properties highly variable 

Relatively inert chemically Reactive (oxidation reactions) 
Recent Revolution in Development and 

Demonstrated Capability

Avoids Filter Analysis Artifacts and Delays

Higher Time Resolution Allows Mobil Mapping 

and Improved Source and Impact Analyses

Field and Lab Instrument Validations and 

Intercomparison Studies Available

Instrumentation for (Near) Real-Time 

Fine PM Chemical Characterization
Recent Fine PM 

Instrumentation Advances

Technique Species Cycle 

Times

Developers

Near Real-Time (Semi-Continuous)

Denuder/PM Scavenging/Ion 

Chromatography

(PILS-IC)

NO3

-

, SO4

=, Cl-

, NO2

-

, NH4

+

Organic acids

2.5-30 

min

P. Dasgupta

R. Weber

J. Slanina

Denuder/PM Collector/Vaporization/Optical 

Vapor Detection (Fluorescence)

(ICVC)

NO3

-

, SO4

=, Organics 2-10 min S. Hering

P. Koutrakos

Denuder/Mo Mesh Converter/Optical Vapor 

Detector

NO3

- 0.5 min E. Edgerton

Growth Tube/Microschip/Electrophoresis

(ACE)

NO3

-

,

, SO4

=, CT 1-10 min S. Hering

J. Collett
Recent Fine PM 

Instrumentation Advances

Technique Species Data 

Acquisition

Developers

Real-Time (Continuous)

Laser Vaporization/Ionization Aerosol 

Mass Spectrometry

(SPMS)

Metals, NO3

-

,SO4

=,Cl-

, 

C/Organics

10 – 30 min K. Prather

M. Johnson/A. 

Wexler

D. Murphy

B. Spengler

A. Zolenyuk

A. Trimborn

Hot Surface Vaporization Aerosol Mass 

Spectrometry

(AMS)

(ACSM)

(TDPBMS)

NO3

-

,SO4

-

,Cl-,NH4

-

, 

Organics

2 s – 30 min J. Jayne/D. 

Worsnop

P. Ziemann

Laser Induced Incandescence

(SP2)

C(soot) 10 s – 15 min D. Baumgardner

Soot Photometry Mass Spectrometry 

(SP-AMS)

C(soot) 2s – 30 min D. Worsnop/T. 

Onasch/G. Kok
Recent Organic PM Speciation Methods

Technique Measurement Time 

Response

Developers

Teflon Filter Collection/FTIR Absorption Organic Functional 

Groups

~ 1 hr L. Russel

Thermal Desorption Aerosol GG/MS

(TAG)

Partial Organic 

Speciation (Marker 

Compounds)

~ 1 hr A. Goldstein

S. Hering
Sulfate Intercomparison

PMTACS Queens New York July 2001

Good correlation between four separate measurement technologies

aerosol measurement technologies are developing

F. Drewnick et al., Atmos. Environ., 37, 3335-3350 (2005)
Queens, New York 

PMTACS

F. Drewnick, K. Demerjian ASRC SUNY Albany

Characteristic Urban Bi-modal Size Distribution

Organic fraction dominates small size mode

Urban Site Jul. 1-Aug. 5, 2001
Aerodyne 

Aerosol Mass Spectrometer

Laser

PMT

• Particles pass through laser beam before impacting vaporizer

• Correlated scattered light and chemical ion signals
FINE PARTICLE COMPOSITION

(Jimenez et al., Science 326, 1525-1529, 2009)
In an oxidizing atmosphere, the oxidation state of carbon increases:

Oxidation of organic species

methane

oxidation

C5 carbon

chain
Oxidation state of organic aerosol

•Average carbon oxidation state can be determined from any analytical

technique that measures elemental ratios (O/C, H/C) of organics

(e.g., High-Resolution Aerosol Mass Spectrometer):

Ox. State ≈ 2 (O/C) – (H/C) 

Averages from HR-AMS measurements in Mexico City:

T0 (morning): -1.0 C-130 (city): -0.4

T0 (afternoon): -0.5 C-130 (outflow): -0.2

C-130 (background): +0.2

Aiken et al., ES&T, 2008

Factor analysis of Mexico City HR-AMS spectra:

Hydrocarbon-like (HOA): -1.7 Oxidized (“fresh”, OOA-2): -0.4...0.0 

Biomass burning (BBOA): -1.0...-0.5 Oxidized (“aged”, OOA-1): +0.5...+1.0
ORGANIC PM ATOMIC RATIOS FROM HIGH RESOLUTION AMS
Products: n-decane (C10H22) oxidation

carbonyls, alcohols, acids only
Oxidation states of organic aerosol

 Organic aerosol is an intermediate in the oxidation

of most organics to CO2

CO2

CO

(“missing source” of SOA?)

[e.g. Heald et al. 2005; de Gouw et al 2005; Volkamer et al 2006]
OXIDATION STATES OF ORGANIC AEROSOL PM
CHEMICAL COMPLEXITY OF AEROSOL PM
FINE ORGANIC PM CHARACTERISTICS
SP-AMS schematic

 Install SP2 module
Schematic of the SP-AMS module

 Absorbing particles (coating and core) vaporize in laser

 Vapor is ionized by electron impact ionization

 Detection of the ions by Time-of-Flight mass spectrometry

 Readily installed in any exiting AMS instrument
SP-AMS Ambient Measurements
SP-AMS Mass Spectra for Ambient 

Particles and Ethylene Flame Soot
Composition and Size Distribution of BC 

Coating and Ageing of BC Containing Particles

Fresh

(downwind LA

0529)

Moderately Aged 

(downwind Santa 

Barbara, 0531)

Aged (downwind 

Santa Monica 0515) 

increasing of total coating mass
Aerosol Inlet 

Thermal Particle 

Vaporization &

Electron Impact 

Aerodynamic Lens Ionization

(0.1 LPM)

Laptop

Computer

RGA

Turbo Pumps

Quadrupole Mass 

Spectrometer Ethernet connection

Diaphragm Roughing Pump

Filter

Automated 3-way 

switching valve

Naphthalene 

Internal Standard

Sampling pump

(3 LPM)

Aerosol Chemical Speciation Monitor
Size: 19”D x 21”W x 32”H 

Weight: 140 lbs 

Power: 300W

universal AC power; 85-264 VAC, 

47-63 Hz

Aerodyne Research, Inc.

Aerosol Chemical Speciation Monitor

ACSM-002 SN 140-100

Shown with Pfeiffer Pumps and Integrated Power Supply
Ng et al., 2011b

Instrument Intercomparisons
FINE ORGANIC PM – HYGROSCOPICITY VS O/C RATIO
Prompt Fine PM Chemical 

Speciation Measurements

-SUMMARYReal-Time/ Near Real-Time Quantification of Fine PM Necessary 

to Understand Climate Impact

Great Advances in Robust, Research Grade, Field Instruments 

Since 2000

Several Instruments Quantify Major Inorganic Components (SO4

=, 

NO3

-

, CI-, NH4

+)

Quantification and General Chemical Characterization of Organic 

Fraction Now Routine

Direct, Real-time Quantification of Elemental Carbon Fraction 

Now Available

More Compact, Less Expensive, Automated Instruments for 

Routine Monitoring Being Developed
ACKNOWLEDGEMENTS

People

ARI

Doug Worsnop

John Jayne

Tim Onasch

Manjula Canagaratna

Sally Ng

Leah Williams

Ed Fortner

Phil Croteau

U. C. Boulder

Jose Jimenez

$

NSF – ACP

NSF – SBIR

DOE – ASR

DOE – SBIR

EPA – STAR

EPA – SBIR

M. I. T. 

Jesse Kroll

C. M. U. 

Neil Donahue

D. M. T.

Greg Kok