Transcript Slide 1

Contributing Efforts to ASCOS
using the Proton Transfer Reaction
Technique for VOC Analysis
M. Müller, M. Graus, A. Wisthaler, A. Hansel
Institute of Ion Physics and Applied Physics, University of Innsbruck, Austria
ASCOS Pre-Expedition Workshop
PTR-MS:
H3O+ + VOC → VOCH+ + H2O
Reaction:
Proton transfer
H3O+
H3O+
H2O+
reaction when
H3O+
H3O+
O+
+
+
+
H3O VOC•H
H
–
H3O+ PA(VOC)>PA(H2O)
OH+ e H3O+
H2O
VOC
ASCOS Pre-Expedition Workshop
What do we detect:
• Most hydro carbons and derivates
 Terpenes
 Aromatics
• Photo oxidation products and other oxyVOCs
 Ketones
 Aldehydes
 Alcohols
• Aerosol precursors
 DMS and oxidation products (DMSO)
 High molecular species (semi volatile)
ASCOS Pre-Expedition Workshop
Performance Summary PTR-MS:
Advantages:
• Compact organic trace gas analyser
• Mostly non dissociative ionization
• Excellent sensitivity
• Low limit of detection ~10 pptv
Disadvantage:
• Poor selectivity
ASCOS Pre-Expedition Workshop
HR PTR-TOFMS:
M.PTR
Graus,
M. Müller, A. Wisthaler,TOF-MS
A. Hansel
Drift Tube
Pulser
Detector
Timing
Signal
Sample Inlet
Acquisition
Time of Flight
ASCOS Pre-Expedition Workshop
Performance Summary HR PTR-TOFMS:
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•
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Detects all ions in one instant
Separation of isobars is possible
Identification of the elemental composition
High sensitivity
Low pptv range LOD
m/z=79.022
ASCOS Pre-Expedition Workshop
m/z=79.055
Planed Innsbruck’s contributions to ASCOS:
VOC air mass
characterization
Continuous
measurements
Aerosol collection (5 stage
BCI) and analysis for
organic compounds
Heli profiles of VOCs
6-8 SilcoCan offline sampling
technique
HLC-Setup
•Molekular mass
•HLC for
identification
•quantitativ
Analysis of solved VOCs in sea water:
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Surface µ-layer samples
Surface layer samples
Off-line thermal
desorption
analysis
Why off-line heli profiles using
6-8 SilcoCans?
Lets look at some AOE 2001 data!
EGU General Assembly 2008
AOE Results by Armin Wisthaler:
Expected SilcoCan Data
EGU General Assembly 2008
AOE Results by Armin Wisthaler:
Expected SilcoCan Data
Very low DMS concentration
=> high signal/noise
High precision data
low signal/noise
Whole mass scans possible
Isobaric identification possible (TOF)
EGU General Assembly 2008
THANK YOU
EGU General Assembly 2008