Guelph (June 98), Simcoe (June 99)
* Dale Sutherland, Activation Laboratories Ltd., Ancaster, Ontario
Ken Byers, Origin and Cause Inc., Ancaster, Ontario
A. D. Sutherland, Activation Laboratories Ltd.
Published in the International Association of Arson Investigators – Ontario Chapter Fall 1999
Some lawyers may argue that the latest generation of laboratory instruments can be so sensitive that a positive result could be determined for the presence of a ignitable liquid in essentially any sample. This is possible in a few forensic applications, such as the FBI’s capability to determine traces of Cocaine, a single organic compound, on every dollar bill in the United States. However, this is not true in the analysis of fire debris for ignitable liquids, as a single compound does not identify them. The samples taken at these seminars provide an ideal opportunity to test this premise as to the potential identification of ignitable liquids in the background of common materials.
The presence of a ignitable liquid is determined by identifying, from the instrumental analysis, specific ignitable liquid patterns, or essentially fingerprints, made up of the combination of these individual hydrocarbons. Gasoline, as an example, consists of a specific mixture of over 200 compounds. If the ratios of the compounds to each other define a pattern that can be compared in good agreement to the pattern for a ignitable liquid in a laboratory reference library, a positive determination can be made. When Gas Chromatography – Mass Spectrometry (GC-MS) is used, multiple patterns or groupings of compounds make this identification, which further improves the level of confidence in the results over that of a single pattern as obtained with other instruments such as a GC-FID or GC-PID.
At Activation Laboratories, GC-MS is used on all samples for fire debris analysis. GC-MS is described as the gold standard because of its capability to filter out interference’s in the analysis by pyrolysates produced in the burning of all materials. Our interpretative program provides over 65 chromatograms for each sample thus obtaining a very high level of confidence in the determination of a positive or negative result. Further to this, in 1997 Activation Laboratories redefined the “state-of-the-art” in the technology used in this field by publishing additional confirmatory method for the analysis of fire debris using GC-MS-MS. This extension to GC-MS is used on complex and very highly weathered samples, and is the same technology used to test the validity of the blood evidence in the high profile O.J.Simpson trial. GC-MS-MS is over ten times more sensitive than GC-MS and is also more specific for the compounds targeted, thus further filtering out pyrolysates and improving the analysis. This new method is used in addition to our standard GC-MS analysis. Its role is to specifically target ignitable liquids in very weak (trace quantity) or very highly weathered samples. When combined with information obtained from the initial GC-MS analysis a significant number of samples that would have been reported as negative by GC-MS alone can be reported as being positive for the presence of a ignitable liquid, with the highest level of confidence attainable.
On June 2nd, 1998, the Ontario Chapter of the IAAI arranged a two-day seminar in Guelph. One highlight of the program was to be the controlled burn of a nearby vacant house, however, the house was sold at the last minute. Thankfully, the Guelph Fire department saved the day by allowing the use of their training tower for the scheduled controlled burn. The Guelph Fire tower had been outfitted with three rooms; a kitchen and a bedroom on the second floor and a combined bedroom-living room on the third floor. Donated furniture such as beds, couches, chairs, cabinets, tables, a coffee maker, hydro-spool coffee table, carpeting, and even a stuffed victim (no distinguishing features) was realistically arranged. Just prior to the setting of the fire at the tower, Ken Byers and Dale Sutherland had the opportunity to take samples of many of these materials to determine the characteristic chemical background of each. All samples were placed in nylon evidence bags (pre-tested). Some of the highlights of the samples analyzed from the fire tower are as follows:
Pre-Burn: A total of 15 samples were taken of various materials prior to the addition of a ignitable liquid. Only one of these samples was identified as having an unacceptable background. The Styrofoam beads from a bean bag chair had the highest level of chemical background. Although this sample was still negative for the presence of a ignitable liquid it would not be the best choice of materials for an investigator to sample as the chemical background would complex the GC-MS analysis. Information from a GC-MS-MS analysis would aid in the determination for this type of sample. Thus, if possible, this material should be avoided. The materials tested included bed mattress fibre, couch foam padding, cloth covering from a fold-out bed, fibre padding from a chair, carpet, kitchen table chair vinyl and padding, and bed mattress foam padding. Even though the furniture and carpet were quite old and well used, and that ignitable liquids had been used several times in the past to conduct training exercises at the tower, none of the 15 samples collected prior to the burn were determined to be positive for the presence of any ignitable liquid.
Post-Burn: Later in the seminar schedule, Dick Walters, President of Origin and Cause as well as a course presenter organized the scenarios in each room and conducted the ignitable liquid pour and ignition. Each room was set ablaze separately and the flame spread observed. Fire fighters then extinguished the blaze. A short time later, samples were again taken and subsequently analyzed with the following results:
Kitchen: The first room set ablaze was the second floor kitchen. The ignitable liquid mixture was poured on a coffee maker that was sitting on a wooden table to simulate an electrical malfunction. After the fire, the Masonite remaining from the back of the desk was sampled at a point below the melted coffee maker. This sample provided an excellent positive for the ignitable liquid.
Foam from the kitchen chair and a wipe of the soot covering the chrome chair railing was taken for analysis. Although the liquid mixture did not come in direct contact with these surfaces a positive result was still obtained by GC-MS although they were relatively weak in strength. This analysis indicated that solid surfaces must be either in very close proximity to the ignitable liquid used, or must have a substantial amount of soot (essentially covering the surface) in order to provide a good sample.
A path of water from the extinguishing of the fire was noted, and had flowed towards a nearby floor drain. This area was still damp and, for experimentation, a paper towel was used to wipe this area. The volume of water used to extinguish the fire was many times the amount of ignitable liquid used, yet, an excellent positive sample was determined from the paper towel.
Second Floor Bedroom: The surface of the bed was slashed and the ignitable liquid mix poured in the center portion of the bed. After the fire the jute under-pad provided an excellent positive result as did the foam pillow and the carpet beside the bed. Surprisingly, the carpet under the bed leg, protected from the fire was also positive although the analysis showed about 15 times less in quantity that the jute sample. Upon inspection of the sample, about 10% of the surface had been burnt. This incomplete protection lead to a positive result. Thus, comparison samples must appear to be essentially pristine, totally protected and untouched by the fire.
Third Floor: The third floor bedroom was ignited by use of a trailer. Some 25 feet of paper towels was placed midway between a long couch and a second shorter couch,. The trailer traveled across a carpet and was used to ignite a bed at the far end of the room. Small amounts of a mixture of medium and high petroleum distillates were added to the trailer. A sample of foam from a burnt portion of the cushions from each couch was taken after the fire. Both were found to be positive. Excellent positive results were also found from small bits of unburned paper that remained. As well, unburned carpet backing at the edge of the trailer burn pattern was also found to be positive without difficulty.
Outside Demonstration: After the commotion at the fire tower, a demonstration was conducted outside on the parking lot. Several pieces of carpet were individually set ablaze in the mid-day sun (75°F) so participants could observe the different flame characteristics obtained from small amounts of different types of ignitable liquids. The liquids used included some from the ASTM Miscellaneous classification groups. After dousing them with water, these carpet samples were left out on the asphalt for about one hour. We were able to collect a few of these samples, which were placed in Nylon evidence bags for laboratory analysis. These samples later tested positive for Acetone, Lighter Fluid and Turpentine.
Ken Byers attended this IAAI Fire Investigation seminar in Simcoe, Ontario. At this meeting two cars were used as test vehicles. Samples were taken of a Chevette and Bonneville prior to the test burn and from the Chevette after the blaze. Sample locations for both vehicles included the driver’s footwell carpet, underpad and seat foam. All of these samples prior to the burn were negative for the presence of a ignitable liquid even though the cars were over 10 years old and extensively used. All of the samples taken after the fire from the Chevette were positive for the presence of gasoline. The carpet again retained most of the ignitable liquids followed by drivers seat foam.
Carpet was found to be the best material in this test in retaining evidence of the ignitable liquids used. This is probably due to the large surface area provided by the thousands of fibres. Carpeting has been documented in the past as being more difficult for the laboratory to analyze. A few of the pyrolysates produced in the burning of carpet are also naturally found in many ignitable liquids. The analysis by GC-MS can generally filter out these pyrolysates and focus on indicators of ignitable liquids. Thus, it is vital that the fire investigator does not rely on an analysis based on Benzene, Toluene and Xylenes or BTEX as commonly offered by Environmental Laboratories. In the environmental sector, BTEX is commonly used as an indicator to determine the presence primarily of gasoline in water or soil samples. These laboratories are largely unaware of the complications and interference’s in the analysis of fire debris and the interpretation necessary in this forensic field which necessitates the use of GC-MS.
With the use of GC-MS and, for more difficult samples requiring more sensitivity the use of GC-MS-MS, interferences previously documented for carpet and for other materials have been essentially overcome. Our tests at the fire tower provided excellent documentation that a positive result cannot be determined in just any material, even with the latest in scientific instrumentation. Another potential contention by litigators may be the previous history of a sample. In these studies, all the material and furniture sampled was well aged and any residues that may at some point have been present in these samples, or from ignitable liquids used previously in the fire tower, or previously tracked into the vehicles that were tested, were not detected. Thus, even today, the best technology has limits of detection, and cannot determine a positive for ignitable liquids in every sample of fire debris. In general, as shown in these tests, the previous history from the standard usage of household contents and automobiles, is not responsible for the positive determination of a ignitable liquid debris after a fire.
The type of information gathered in these studies is vital to court presentations. Activation Laboratories would like to acknowledge and thank the Ontario Chapter of the IAAI for these seminars and for allowing us the opportunity to conduct this research as part of these demonstrations. We very much appreciate the cooperation and help in taking the samples by Ken Byers of Origin and Cause, the Guelph Fire Department for providing the fire tower and their professional fire fighting services, and Arlene Sutherland for assistance in the GC-MS analysis of all 38 samples taken in the Guelph study.