RestekCorporation
(800) 356-1688
ClinicalForensic
FireDebrisAnalysis
note
A
pplications
cat.#59574
Figure 1
ResolutionCheckMixdemonstratesproper columnperformance.
Capillarygas chromatography is the
methodof choice for analyzing
suspected arson samples from fire
debris. Becauseof the complex
compositionofmost accelerants used in
arson cases, it is crucial that positive
identificationbemadeof thematerial
used to start the fire. TheAmerican
Society forTestingMaterials (ASTM)
has developed standard test procedures
for analyzing these samples. The
informationpresented in this article
referencesASTME1387, “Standard
TestMethod for FlammableorCom-
bustibleLiquidResidues inExtracts
fromSamples of FireDebris byGas
Chromatography”.
Aswith all analytical procedures,
sample collection, preservation, chain
of custody, and samplepreparationplay
crucial roles in the process. Samples
maybe extractedusing several different
techniques
1
(beyond the scopeof this
article) for introduction into thegas
chromatograph.
Appropriatecapillarycolumn selection
is the first decision the analystmust
make. TheASTM standard allows the
useof any capillary column and
conditions, provided that aResolution
TestMix is completely resolved into the
individual components. This resolution
testmix consists of equalweights of the
evennumberedn-alkanes fromC6 to
C20, plus several aromatic compounds.
The aromatics specified are: p-xylene,
toluene, 2-ethyltoluene, 3-ethyltoluene,
and1,2,4-trimethylbenzene.
Several different stationaryphases and
column configurations canprovide the
resolutionneeded. Typically, laborato-
ries canuse30-meter columns coated
with eitherRtx
®
-1 (100%dimethyl
polysiloxane) orRtx
®
-5 (5%diphenyl
95%dimethyl polysiloxane). Film
thicknesses canvary from1.0 to1.5µm.
Choiceof column ID shoulddepend
upon sample capacity and thedetection
system employed. The standard allows
for the use of either FIDorMS
detectors. IfMSdetection is employed,
use a0.25mm ID column tominimize
carrier gas flow. If FIDdetection is
employed, use a0.53mm ID tomaxi-
mize column capacity.Useof 0.53mm
ID columns canminimize expensive
duplicate analyses or dilutions if the
concentrationof accelerants arevery
high.
Figure1
shows the complete
resolutionof all 13 components in the
column resolution checkmixon a30m,
0.53mm ID, 1.5µmRtx
®
-1 columnwith
anFIDdetector. The linear velocity and
temperatureprogram chosen allow the
entire analysis tobe completed in
approximately16minutes.
1. hexane
2. toluene
3. octane
4. p-xylene
5. 3-ethyltoluene
6. 2-ethyltoluene
30m, 0.53mm ID, 1.50µmRtx
®
-1 (cat.# 10170).
1.0µl split injection of E1387-90 Column Resolution CheckMix (cat.# 31224).
Oven temp.:
40°C (hold 3min.) to 75°C@ 15°C/min. to 275°C@ 20°C/min. (hold 5min.);
Inj./det. temp.:
250°C/285°C;
Carrier gas:
hydrogen;
Linear velocity:
50cm/sec. set @ 40°C;
FID sensitivity:
4.10 x 10
-9
AFS
Split ratio:
30:1
1
2
3
4 5 6
8
9
10
11
7
12 13
2 4
22 24 26 28
14 16 18 20
6 8 10 12
min.
30 32 34 36
7. 1,2,4-trimethylbenzene
8. decane
9. dodecane
10. tetradecane
11. hexadecane
12. octadecane
13. eicosane
