Analyzing SPARTAN filters with an Aerosol Mass Spectrometer

Rachel O’Brien, Kelsey Ridley, Jesse KrollDepartment of Civil and Environmental Engineering, MIT

Manjula Canagaratna, John Jayne, Philip Croteau,Aerodyne Research, Inc.

June 9, 2015

High Resolution-TOF-AMS

• Aerosol Mass Spectrometer with a Time of Flight mass spectrometer• Measure refractory aerosol species • Resolution ~ 2-3k m/Dm

AMS studies worldwide… costly deployment, few long term data sets

Zhang et al., 2007organic sulfate nitrate ammonium

Filters and off-line analysis

• Global filter networks long term data sets, lower deployment cost, more remote and difficult locations

• Filter extracts small sample volumes

Small Volume Nebulizer (SVN) design

Minimum concentration ~0.15 g L-1 (20-30 mg into ~100 mL to be above LOD)

Clean house air

Kapton Polyimide film

AMS

Ultrasonic transducer

Good correlation with commercial atomizer

TSI Atomizer

SVN

TSI Atomizer

SVN

Inter-instrument comparison

0.0001

0.001

0.01

0.1

Onl

ine

aero

sol m

ass

spec

trum

(ion

sign

al n

orm

aliz

ed to

1)

0.0001 0.001 0.01 0.1

Offline aerosol mass spectrum(ion signal normalized to 1)

13

24

25

26

27

30

3738

41

42

4344

45

48

49

5051

52

53

54

55

56

5758

59

60

61

6263

6465

66

6768

697071

7273

74

75

76

77

78

79

80

81

82

83

8485

86

87

8889

90

91

92

9394

9596

979899100

101

102

103104

10516

17

18

15

29

31

Filter extract (AMS)Fi

lter e

xtra

ct (A

CSM

)m/z

Nor

mal

ize re

lativ

e in

tens

ity

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00

10080604020

0.15

0.10

0.05

0.00

10080604020

ACSM

AMS

0.10

0.08

0.06

0.04

0.02

0.00

Nitr

ate

equi

vale

nt m

ass

µg/

m3

*

10080604020m/z

HR-MS from Bandung, Indonesia: August 19-20, 2014

OrgSO4

NO3

NH4

O/C = 0.6Org/SO4 = ~6

Future development

• Continuous injection• Add automation, improve sensitivity

• Addition of internal standard • Mass quantification

• Orthogonal analyses– UV/Vis, fluorescence, etc.

Syringe pump

AMS

Conclusions

• The SVN can be used to generate AMS spectra from SPARTAN filters:

• Ensemble organic composition, O/C• Need > 20-30 mg of sample• Extract filters in water

• Ongoing development to improve utility of the SVN:• Quantification• Increased sensitivity• Orthogonal analyses

Acknowledgments

• Kelsey Ridley, Jesse Kroll and the Kroll group

• Manjula Canagaratna, John Jayne, Philip Croteau, and Aerodyne Research, Inc.