Use Of Headspace Gas Chromatography In The
Detection Of Accelerants On Arson Debris
Presented by : Suliman Atallah
University Of Huddersfield
Ministry Of Interior -Libya
Aims:
To optimise experimental conditions for headspace
gas chromatography (HS-GC) in the analysis of
accelerants.
To investigate the effect of partial burning on the
chromatograph profile of accelerant.
Introduction:
Arson is the main cause of fire, which costs
the UK an estimated £2 billion a year. The
majority of arson attacks in the UK are on
residential properties. Each year there are
about 87,095 attacks on homes, which kill 65
people and injure 2010. (1)
Forensic fire investigation involves the
detection of accelerant residue in fire debris
that has been collected from a fire scene.(2)
This study will focus on the effectiveness of
manual and automated HS-GC in detecting
fuel in accelerants
Equipment and materials:
•Varian 3900 gas chromatography and Autoheadspace Agilent 7697, in conjunction with
8690 Gas chromatography, were fitted with a
flame ionization detector and capillary column.
•Two columns were used and compared: BP20
(polar) and BPX-5 (non-polar). Both columns
were 25 m in length with a 320 um bore.
• The accelerants studied included petrol, white
spirit, aviation fuel, kerosene, diesel and pure
turpentine.
SULIMAN8686@YAHOO.CO.UK
Method:
• The studies on fire debris utilised petrol and
white spirit which were placed on clothes
samples (7.5cm x 9.5cm) and burnt under
fixed conditions.
• Residues were collected in nylon bags for
analysis.
• Sample analysis was carried out using 1 μl
injections, a temperature program of
40°C/min from 50 °C to 230 °C with an
initial 2 minute hold.
• The helium gas flow rate was 25ml/min
(split1:20) and a detector temperature of 330
°C.
Results:
Both of these chromatograms demonstrate the
differentiation view between a petrol component
injected as a liquid sample, and a gas sample
which was taken from the HS- vial containing the
petrol sample.
Each point represents a peak in the chromatograph
normalised with respect to the largest peak and
showing how the ratio in peak sizes varies between the
liquid and the vapour.
No petrol residues were found on any of the pieces of
burnt clothes.
Discussion and Conclusion
• The chromatograph of the liquid and the
headspace of a pure accelerant were very
different. The less volatile components were not
detected using headspace.
• Manual / automated headspace injection gave a
better resolution result with the BPX-5 column
rather than the BP-20 column.
• Reliable analysis of arson accelerants is limited
with GC-FID, as peaks cannot be identified. GCMS would be a better instrument where each
component in the mixture can be identified.
References
1.www.devon.cornwall.police.uk/YourRightInform
ation/FreedomInformation/Lists/DisclosureLogs.
2.Recent advances in the applications of forensic
science to fire debris analysis, J. Dolan , 2003,
published by Springer-Verlag USA.