Detection of Gas Phase Chemical Detection of Gas Phase Chemical Warfare Agents using Field Warfare Agents using Field - - Portable Portable Gas Chromatography Gas Chromatography - - Mass Mass Spectrometry Systems: Instrument Spectrometry Systems: Instrument and Sampling Strategy and Sampling Strategy Considerations Considerations
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Detection of Gas Phase Chemical Warfare Agents using Field
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Detection of Gas Phase Chemical Detection of Gas Phase Chemical Warfare Agents using FieldWarfare Agents using Field--Portable Portable
Gas ChromatographyGas Chromatography--Mass Mass Spectrometry Systems: Instrument Spectrometry Systems: Instrument
and Sampling Strategy and Sampling Strategy ConsiderationsConsiderations
Capabilities without InstrumentationM8 PaperM8 Paper(simple)(simple)
M256 KitM256 Kit(complicated)(complicated)
P
O
O
CH3
H3C CH3S Cl
Why use GC-MS?
(1) “Gold standard” orthogonal data provided
(2) Capable of identifying unknown compoundsby mass spectrum match
Arguing against GC-MS use:
(1) Large, power-hungry instrument
(2) Spectral interpretation can be difficult
(3) Sample prep, analysis can take considerable time
GC-MS “guts”-two approaches
Man-portable instrument
Resistively-heated LTM GC column
Field-portable instrument
Field-portable instrument
GB
GD HD
GF
Man-portable GC-MS system
Solid Phase Microextraction (SPME)as field sampling method, followedby GC-MS analysis in a more capablefield instrument package
2 of 3 fibers extended for sampling;Circled area has sorbent coating of1 fiber
Rapid Combined Sampling/Analysis5 min SPME samples from contaminated air
Use low thermal mass resistivelyheated columnIn place of airBath GC oven
2.0Retention time (min)
120 °C/min
40° C/min
GB GDHD
GF
30s SPMEHeadspace
AboveContaminated Cloth
2.5 min total analysis
Sarin SomanSulfurmustard
GF1s SPME
2s SPME
15s SPME
LTM resistivelyheated columnIn place of airBath GC oven
Rapid Combined Sampling/Analysis5 min SPME samples from contaminated water
GB140 AMU
GD182 AMU
HD158 AMU
GA162 AMU
VX267 AMU
T2 Toxin466 AMU
LTM resistivelyheated columnIn place of airBath GC oven
Need: Test atmosphere with a wide rangeof chemicals having different properties
Hapsite and SPME sampling selectivity can be studied with
such an atmosphere
(CS)
CH3Cl
C
N
ClCN
ClCNNC
Cl
CH
O
Hapsite sampledsuccessfully for
Volatiles in this range(next slide)
5 min passive SPMESample shown here,field GC/MS analysis
Cl
C8H10 isomers(ethylbenzene, xylenes)
CH3
Benzonitrile not observed
TenaxConcentratorSampleIntroduction
Hapsite SelectivitySame atmosphere sampled as previous
slide only light compounds observed
Cl
Gas LoopSample Introduction
(CS)
CH3Cl
C
N
ClCN
ClCNNC
Cl
CH
O
Hapsite sampledsuccessfully for
Volatiles in this range(previous slide)
5 min passive SPMESample shown here,field GC/MS analysis
Hapsite Hapsite SPME/GC-MS(MS-only)
Mass of sampler 16 kg 16 kg 0.035 kg
Sample throughput 3/hr >10/hr? >10/hr?
GC/MS systems 3 1 1and operatorsneeded for 10samples/hr
Cost for GC-MS $300k+ $100k+ $140kSystem(s) sufficientfor 10 samples/hr
Next?Next?
Build prototype low thermal mass GC columnmated directly to a mass spectrometer –a drastic reduction ofmass, footprint, and volume with superior heating/coolingcharacteristics
Laboratory-gradeinstrument capabilitieswithout the van