Molecular Characterization of Organic Aerosols from the Los Angeles Ground Site during the

CalNex 2010 Campaign Using High-Resolution Mass Spectrometry

T. Nguyen, N. Levac, D. Bones, A. Bateman, S. NizkorodovUniversity of California, Irvine

A. Laskin, J. Laskin, P. Roach, B. HeathPNNL

Specific Objective: Nitrogen Containing Organic Compounds

• Ubiquitous in atmospheric aerosol, yet poorly characterized on a molecular level

• May contributed to adverse health effects of particulate matter

• May absorb visible light and contribute to “brown carbon” aerosol

Conventional "Brown Carbon"• HULIS from biomass burning• Organic light-absorbing material from vehicular

emissionsAndreae, Gelencser, Atmos. Chem. Phys. 2006 Jacobson J. Geophys. Res. 1999

"Brown Carbon" from SOA Aging

Fresh SOA: scatters light; COOLS the surface

NH3 or amines

Aged SOA: absorbs light; WARMS the surface

• Known to contain hetero-N compounds• Both biogenic and anthropogenic SOA undergo this type of aging

Laboratory Studies (e.g. Bones et al, JGR 2010; Laskin J, et al Anal.Chem. 2010; Nakayama et al, JGR2010; De Haan et al, EST 2011)

Field Observations: Mexico city (Roach, et al Anal.Chem. 2010), Shanghai (Wang et al, EST 2010)

PILS (Particle-Into-Liquid Sampler)Particles collected straight in water30 min per sample

Types of Samples Collected

Substrates for SEM/EDX, X-ray spectro-microscopy, and Ice Nucleation studies

MOUDI Cascade Impactor

Particles collected on Teflon and Al foil substrates6-hours per set of size segregated samples0-6 am; 6 am - noon; noon -6 pm; 6 pm - midnight

PILS

High-Res.MS

Optical Microscopy of Heterogeneous Ice Nucleation

Bingbing Wang Dr. Daniel Knopf

Poster 38

Advantages of High Resolution MS

Analysis of OA Using Nano-DESI MS

Routine analysis of <10 ng OA Probe size <100 mm

Promising Days for the HR-MS AnalysisAMS data from P. Hayes, J. Jimenez et al. (U. Colorado)

June 5: unusually large “ amine OA" signal in the morning

Nano DESI HR-MS

0 200 400 600 800 1000 12000

1x104

2x104

3x104

4x104

5x104

6x104

inte

nsity

, arb

. uni

ts

m/z

June 5 IB-6

200 400 600 800 1000 12000.0

5.0x103

1.0x104

1.5x104

2.0x104

2.5x104

3.0x104

3.5x104

4.0x104

inte

nsity

, arb

. uni

ts

m/z

June 5 IIA-6

200 400 600 800 1000 12000

1x104

2x104

3x104

4x104

5x104

inte

nsity

, arb

. uni

ts

m/z

June 5 IIIB-6

200 400 600 800 1000 12000

1x104

2x104

3x104

4x104

5x104

inte

nsity

, arb

. uni

ts

m/z

June 5 IVA-6

200 400 600 800 1000 12000.0

5.0x104

1.0x105

1.5x105

2.0x105

inte

nsity

, arb

. uni

ts

m/z

June 6 IIB-6

LVOOALVOOA

SVOOA

SVOOA

~40% peaks assigned

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

100 300 500 700 900

LVOOA and SVOOA are Chemically Related

C15H26O -(CH2)x H+

C16H30O3 -(CH2)x H+

C20H36O4 -(CH2)x H+

C38H64O6-(CH2)x H+

KMCH2, Da

KMD CH

2

(sample 6:00-12:00) LVOOA

SVOOA

0.0 0.1 0.2 0.3 0.4 0.5 0.60.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35fra

ctio

n

O/C

June 5 IB-6

0.0 0.1 0.2 0.3 0.4 0.5 0.60.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

fract

ion

O/C

June 5 IIa-6

0.0 0.1 0.2 0.3 0.4 0.5 0.60.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

fract

ion

O/C

June 5 IIIA-6

0.0 0.1 0.2 0.3 0.4 0.5 0.60.0

0.1

0.2

0.3

fract

ion

O/C

June 5 IVA-6

O/C Histograms

0:00-6:00 6:00-12:00

12:00-18:00 18:00-24:00

CxHyNz fresh emissions..?

0.0 0.1 0.2 0.3 0.4 0.5 0.60.0

0.1

0.2

0.3

0.4

0.5

0.6

fract

ion

N/C

June 5 IB-6

0.0 0.1 0.2 0.3 0.4 0.5 0.60.0

0.1

0.2

0.3

0.4

0.5

0.6

fract

ion

N/C

June 5 IB-6

0.0 0.1 0.2 0.3 0.4 0.5 0.60.0

0.1

0.2

0.3

0.4

0.5

0.6

fract

ion

N/C

June 5 IB-6

0.0 0.1 0.2 0.3 0.4 0.5 0.60.0

0.1

0.2

0.3

0.4

0.5

0.6

fract

ion

N/C

June 5 IB-6

N/C Histograms

0:00-6:00 6:00-12:00

12:00-18:00 18:00-24:00

CxHyNz

N-Organics in CARES samples (DOE 2010 field study)

Photos: S. Springston R. Zaveri

Sacramento, T0 site

Nanospray DESI – Line Scan Analysis

Nanospray DESI – Line Scan Analysis

200 300 400 500 600

1x103

2x103

3x103

4x103

5x103

6x103

7x103

inte

nsity

, arb

. uni

ts

m/z

CxHyN1CxHyN2

5

7

9

11

13

15

17

19

21

23

25

150 200 250 300 350 400 450 500 550

N1 speciesN2 speciesN>3 species

DBE

m/z

or

C16H11N1

Brown C Event

• CxHyNz – organics are ubiquitous in urban OAPossible Sources:

25% of identified peaks are:aliphatic CxHyN1, CxHyOzN1

- Amines

• CxHyN1 – are also observed at the Bakersfield site(R. Sellon, A. Goldstein, et al - Poster 31)

Intensive Road Construction Activity at the Time of CxHyNz

Episode (field notes of R. Zaveri) oFumes of Asphaltenes …?oEmissions from Vehicles with Catalytical Converters

…?

Outlook: PILS vs DESI: June 5, 12-6 pm

Very different subsets of compounds detected by two methods

Multiply Charged Ions in PILS Spectra (M-Ca2+, M-Mg2+, …)

Time Series of WSOC Detected by PILS

SUMMARY• Molecular-level HR-MS analysis provides critical

information for interpretation of the OA types, their chemistry

• Essential to assist with more detailed classification

• Outlook: Closure studies with the OA optical properties data indicative of “brown carbon”Closure studies with the gas phase, VOC data focused on chemistry of SOA formation and aging