Detection of Ignitable Liquids
from Smoke Residues by
Large Volume Static
Headspace
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Presentation Overview
• Introduction to Large Volume Static Headspace
(LVSH) Technique
• Analytical Procedure
• Data from Arson and Non Arson Fire
• Summary
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GC/MS Detection Limits vs Headspace Sample Volume
1000
Loop
100
Preconcentration
P
P 10
M 1
L 0.1
O
0.01
D
10-3
10-4
10-5
0.001
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0.01
0.1
1.0
10
MINIMUM VOLUME REQUIRED (CC)
100
1000
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Lack of Water Management
400cc VOC STD, Full Scan 15-270 amu
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Large Volume Headspace
Requires Preconcentration
HP 5973 GCMS
Volume Reduction
Large Volume
Inlet or Autosampler
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Large Volume Static Headspace
Autosampler
• Introduces 10-200cc of
headspace to the 7100
Preconcentrator
• Accommodates solids and
liquids
• Detection limits 100x
lower than conventional
loop injection headspace
• “See what your BDU can
smell”
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LVSH Sample Platforms and Enclosures
• Evidence collection and analysis
use the same enclosure reducing
potential for contamination of
samples.
• Sample Platforms use quick
connects, simplifying removal
for cleaning.
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7032-LVSH / 7100 /5973
Large Volume Static Headspace Analyzer
M3
M2
SL I/O
SL I/O
6
M1
MS
GC
7100
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7032-LVSH
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7100 Open Architecture
Modular design.
Easy replacement of traps
MFC downstream of traps
PCB Integrated wiring for
improved reliability
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7100 Heated Flow Path
• Silonite tubing used
throughout.
•Complete heating of
sample flow path. Easily
accessed for trap and
tubing replacement.
•External Heaters
outside each cryotrap
7100 Preconcentrator
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7100 Water and CO2 Management Techniques
Loading Internal Standard
MFC
PUMP
N2, O2
Helium Carrier
Helium
To
GC
Focuser
Sample
Internal
Standard
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Calibration Sample
Standard
Glass Beads
Tenax
Cryogen in
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7100 Water and CO2 Management Techniques
Loading Calibration Standard
MFC
PUMP
Helium Carrier
N2,O2
Helium
To
GC
Focuser
Sample
Internal
Standard
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Calibration
Standard
Glass Beads
Tenax
Cryogen in
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7100 Water and CO2 Management Techniques
MFC
Loading Sample
PUMP
Helium Carrier
N2, O2,
Ar, CH4
Helium
To
GC
CO2
H2O
Focuser
VOCs
Sample
Internal
Standard
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Calibration
Standard
Glass Beads
Tenax
Cryogen in
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7100 Water and CO2 Management Techniques
MFC
Flushing Traps
PUMP
Helium Carrier
N2, O2,
Ar, CH4
Helium
To
GC
CO2
H2O
Focuser
VOCs
Sample
Internal
Standard
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Calibration
Standard
Glass Beads
Tenax
Cryogen in
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7100 Water and CO2 Management Techniques
MFC
Removing Water and CO2
PUMP
CO2
Helium Carrier
Helium
To
GC
H2O
Sample
Internal
Standard
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Calibration
Standard
Glass Beads
VOCs
Focuser
Tenax
Cryogen in
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7100 Water and CO2 Management Techniques
Focusing Sample before Injection
MFC
PUMP
Helium Carrier
Helium
VOCs
To GC
VOCs
Focuser
Sample
Internal
Standard
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Calibration
Standard
Glass Beads
Tenax
Cryogen in
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7100 Water and CO2 Management Techniques
MFC
Post-Injection Bakeout
PUMP
H2O
Helium Carrier
Helium
To
GC
Focuser
Sample
Internal
Standard
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Calibration
Standard
Glass Beads
Tenax
Cryogen in
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Evidence Collection
Glass fragments from the room of origin are collected in glass jars. Analysis of the
headspace dose not require transferring the sample
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Data Comparison:
Room 1 vs Room 4 -100cc sample
• No Ignitable Liquids
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• Gasoline-Diesel Mix
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ASTM Class 2 Data Comparison
Xylenes & C3 Alkylbenzene
• No Ignitable Liquids
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• Gasoline-Diesel Mix
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ASTM Class 2 Data Comparison
Benzene & Toluene
• No Ignitable Liquids
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• Gasoline-Diesel Mix
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ASTM Class 2 Data Comparison
Naphthalines
• No Ignitable Liquids
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• Gasoline-Diesel Mix
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Advantages of LVSH Sample
Collection
• Samples can be collected if the point of origin has
been obscured.
• Samples can be collected well after the fire has been
extinguished.
• Clear jars allow evidence to be displayed at trial
without compromising sample integrity.
• Small jars allow for easy sample transport.
• Samples can be split or co-located for defense.
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Conclusion
• Large Volume Static Headspace (LVSH) is a new
analytical tool available to Forensic Chemists which
enhances detection limits while using current GC and
GCMS systems.
• ASTM Reference Compounds are easily Identified in
High Concentration when Compared to Non
Combustible Liquid Fires.
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