Air Pollution Research Using Chemical Ionization Mass Spectrometry (CIMS)Spectrometry (CIMS)

Jun Zheng, Ph.D.Jiangsu Key Laboratory of Atmospheric Environment 

Monitoring and Pollution Control (AEMPC)Nanjing University of Information Science & Technology

Oct 26, 2012 Nanjing

Soft IonizationHigh Sensitivityg yHigh SelectivityVersatilityVersatility

Ion Chemistry: R(+/‐) + A P(+/‐) + BR(+/ ) + A  P(+/ ) + B

Huey, L. G. (2007), Mass Spectrom. Rev., 26(2).Huey, L. G. (2007), Mass Spectrom. Rev., 26(2).

Applications of CIMS in Atmospheric h dChemistry Study

Fi ld t t f• Field measurements: trace gases, free radicals…

• Laboratory experiments:– Kinetics 

– Uptake coefficient

– Chamber simulations…

1. Proton‐Transfer‐Reaction Mass ( )Spectrometry (PTR‐MS)

H3O+∙(H2O)n + R  RH+ + H2O(n+1), (R = VOCs)3 ( 2 )n 2 (n+1), ( )

where n = 0, 1 and corresponding rate constants are k’0 and k’1, respectively.

[R] = [RH+] / (k’0[H3O+] + k’1[H3O+∙H2O])[R]t.

Ionicon Analytik Inc.

PTR‐MS Field Measurements

Toluene Styrene C2‐BenzeneToluene Styrene C2-Benzene

C3‐Benzene Methanol AcetaldehydeC3-Benzene Methanol Acetaldehyde

Atmos. Chem. Phys. 2009, 9, 467‐481.

VOCs Source Apportionments

VOC NOx

SO2 NOSO2 NOz

PTR‐MS for HCHO Measurements

H3O+ + HCHO  H+HCHO + H2O 

Zheng et al., Atmos. Environ. 2012, Accepted 

Mobile VOCs Measurements

Case1: before vehicle control Case2: vehicle control before OlympicsCase3: Olympics Case4: between Olympics and Paralympics Case5: ParalympicsCase5: ParalympicsCase6: After vehicle controlCase7: National days

Atmos. Chem. Phys. 2009, 9, 8247‐8263.

2. Ion Drift – CIMS2. Ion Drift  CIMS

•Bipolar detector•Well‐controlled ion‐molecular reactionC bl f d l t i•Capable of declustering

ID‐CIMSHNO3 Detection: SF6 + e‐ SF6‐

SF6‐ + SiF4 SiF5‐ + SF56 4 5 5SiF5‐ + HNO3 SiF5‐HNO3

N O Detection:N2O5 Detection: CF3I + e‐ I‐ + CF3I‐ + N2O5 NO3

‐ + INO2

ID‐CIMS

Lei, W. F., R. Y. Zhang, X. X. Tie, and P. Hess (2004), Chemical characterization of ozone formation in the Houston‐Galveston area: A chemical transport model study, J. Geophys. Res., 109(D12), D12301, 10.1029/2003jd004219

ID‐CIMS

HONO Detection: SF + e‐ SF ‐SF6 + e SF6SF6‐ + HONO  HONOF‐ + SF5

(ppb

v)

30

40 ID-CIMSU. Miami LOPAP

ppbv)

HO

NO

(

10

20

HONO (p

CST

5/23 10:45 5/23 10:50 5/23 10:55 5/23 11:000

ID‐CIMS2000

ptv)

1500

2000

pptv) 2009  In Houston, Texas

HO

NO

(p

500

1000

HONO (p

CST4/20 00 4/27 00 5/4 00 5/11 00 5/18 00 5/25 00 6/1 000

2009  In Shanghai, China

3. Atmospheric Pressure IonizationID‐CIMS

Schematic diagram of the AP‐ID‐CIMS. 

Chemical Scheme: NO - (HNO ) + H SO HSO - (HNO ) + HNO n = 0 1 2 Chemical Scheme: NO3 (HNO3)n + H2SO4 HSO4 (HNO3)n + HNO3, n = 0,1,2… Quantification: [H2SO4] = [HSO4

-HNO3] / (k∆t[NO3-HNO3])

By introducing a 4-in ID inlet for sampling, the wall losses can besignificantly decreased.

Well suited for the detection of ultra-trace atmospheric components, such asgaseous sulfuric acid (the detection limit as low as 0.01 ppt).

API‐ID‐CIMS

2008 Beijing2008 Beijing

API‐ID‐CIMSNucleation Events During CAREBeijing 2008

080717

4.E+04

5.E+04

6.E+04

(/cm

3 ) 2 .0E+06

2.5E+06

3.0E+06

H2 SO

4

N uc leation

H2SO4

Nucleation Events During CAREBeijing 2008

0.E+00

1.E+04

2.E+04

3.E+04

00 04 08 12 16 20 00T ime

N－

Nuc

(

0 .0E+00

5.0E+05

1.0E+06

1.5E+06

（/cm

3）

JT JT0([H2SO4 ] )a a ( RH )b b ( [NH3] )c c

a = 2.17 in Beijing, indicating 2 H2SO4 molecules were involved in the nucleation

JT JT ([H2SO4 ] 0

) (RH0

) ([NH 3]0

)

McGraw, R., and Zhang, R. Y., J. Chem. Phys., 128, 2008. 

a 2.17 in Beijing, indicating 2 H2SO4 molecules were involved in the nucleation

Zheng, J. et al., Atmos. Chem. Phys., 11, 2011.

4. High Resolution Time of Flight‐CIMS4. High Resolution Time of Flight CIMS

HRToF‐ID‐CIMS

Aerodyne HRToF‐CIMS

O2+

CH5NH+

Amonia and Amines in Nanjing 2012

CH5N H

AcknowledgementsAcknowledgements

• Prof Renyi ZhangProf. Renyi Zhang 

• Prof. Mindong Chen

f i i Ch• Prof. Jianmin Chen

• Prof. Min Hu

• Prof. Yan Ma

• Prof Lin WangProf. Lin Wang

Thank you for your attention！