Forensics

Gas Chromatography Analysis

Forensic Services Newsletter

The subject of this newsletter is to explain recent developments in our fire investigation service, which has improved our speed in reporting on the presence or not of accelerants*. The analysis of samples from fire sites is a standard practice among fire investigators. The reason for the analysis is to detect the presence of flammable liquids (common ones include petrol, kerosene and diesel) used to speed up the spread of a fire. In the laboratory, identification of ordinary samples of petrol, kerosene and diesel is a relatively straightforward process. It is a different matter when samples are taken from fire sites that have been burning for hours!

Much of the success in testing for accelerants relies on sound methodology at the fire site. This includes the proper collection and storage of the samples, while at the same time avoiding common pitfalls such as natural contamination from chemicals legitimately present or breakdown products from burnt plastics (which are derived from petroleum). Evidence of the presence of accelerants found by our consultants has been presented to courts of law in Malaysia, the Philippines and Thailand.

GC

Our certified chemist, Kavitha Krishnan, using our gas chromatograph

Previously, we sent our samples to the Geronimo Fire Investigation Laboratory at the University of Technology, Sydney. Analysis was carried out under the supervision of Professor Wal Stern, whereby volatile chemicals were extracted with a passive absorption technique, and analysed by gas chromatography. At that time, Professor Stern routinely provided services to the insurance industry in New South Wales, Australia. Although the service from this laboratory was excellent, we found that the transport time combined with the strict Australian quarantine requirements usually resulted in a turnaround time of 7 to 8 days. This became too slow for the Malaysian insurance industry, and we took steps to set up our own in-house laboratory.

Currently, our in-house laboratory uses the gas chromatography, or more specifically, the Flame Ionization Detector (GC-FID) to detect the presence of liquid ignitables. The laboratory was set up under the direction of Professor Wal Stern and is operated by Kavitha Krishnan, a Masters degree holder in Analytical Chemistry, and one of our consultants. Professor Stern remains our advisor.

FLASH POINT (Celcius)
Acetic acid 40 Methanol 11
Acetone -18 Turpentine substitute 38
Benzene -10 Nitrocellulose 13
Butanol 35 n-Octane 13
Diesel 43 to 48 Palm kernel oil 398
Ethanol 12 Palm oil 203
Ethyl acetate -4 Paraffin wax 198
Ethylene alc. (glycol) 116 Petroleum, crude -7 to +32
Formaldehyde 60 to 80 Propanol 25
Gasoline (pertol) -45 Toluene 4
n-Hexane -23 Turpentine (nat) 32 to 46
Kerosene (paraffin) 38 to 74 Whisky 28
Lubricating oil (min.) 150 Xylene 25
A simplified definition of flash point is that it is the lowest temperature at which a liquid will produce a flammable vapour.

With our in-house laboratory, sample analysis results are available within 24 hours of the sample reaching our laboratory. Our gas chromatography method can find as little as 1 microlitre (0.000001 litre) of liquid ignitables in a kilogram of fire debris. When necessary we also have gas chromatography-mass spectrometry (GC-MS) performed.

While on the subject of fire and accelerants, we provide below a table showing the flash points of common flammable liquids.

*Accelerant : An agent, often an ignitable liquid, used to initiate or speed the spread of fire.

Regards,


Barry Dillon

Business Set Up to Burn | Self Heating of Farm Produce | Hot Work Accidents | Chinese Altars | Textile Fires | GC Analysis | On-Board Marine Investigations | Pre-Fire Photographs | Furniture Fires in Malaysia | Medium Density Board Factory Fires