Fixing False Negatives, Using 2DGC-TOFMS to Correctly Identify Ignitable Liquid Residues (ILRs) in Wildfire Investigations - Pittcon 2019
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Wildfires continue to grow in frequency and intensity. Over 80% of wildfires are human caused, with over 20% being attributed to acts of arson. The ability to detect ignitable liquid residues (ILRs) in wildfire debris samples can be very problematic compared to structural fire debris samples. Forensic methods used in the analysis of wildfire debris are complicated by the presence of natural interferences. Wildfires provide exceptionally difficult matrices compared to structural fires due to the facts that: ILRs are present at lower concentrations; ILRs are more dispersed; natural compounds are present at very high concentrations; structural similarity of natural compounds to ILR compounds; and matrix combustion forms other interfering compounds. The resolving power of comprehensive two-dimensional gas chromatography (GCxGC, 2DGC) combined with the sensitivity of a TOF-MS permits superior separation and detection of ILRs compared to conventional gas chromatography (1DGC). The high abundance of natural interferences dwarfs the ILR compounds in size and will mask their detection using conventional 1DGC. As arsonous wildfires can ignite with very low volumes of accelerants, better detection limits are required in order to find and identify ILRs in wildfire debris samples. Case samples analyzed on both 1DGC and 2DGC showed re-analysis by 2DGC changed 7% of negative samples to positive for ILR, and 22% went from tentative to positive for ILR. Inspection of the Stauffer compounds shows some groups are more useful for ILR identification than others. The Three Musketeers Group was ubiquitous, while the Twin Towers and Five Fingers Groups were non-detects by 1DGC but present in up to 90% of positive samples by 2DGC. In addition, the use of 2DGC allows expansion of the targeted list of compounds to expand to all compounds present in gasoline which increase to over 2000 compounds, potentially allowing for gasoline fingerprinting.
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Fixing False Negatives, Using 2DGC-TOFMS to Correctly Identify Ignitable Liquid Residues (ILRs) in Wildfire Investigations - Pittcon 2019
- 1. © 2019 Chemistry Matters Inc. Fixing False Negatives, Using 2DGC-TOFMS to Correctly Identify Ignitable Liquid Residues (ILRs) in Wildfire Investigations March 18, 2019 Pittcon 2019, Philadelphia, PA Court Sandau, PhD Principal, Chemistry Matters Inc., Calgary, AB Adjunct Professor, Mount Royal University, Calgary, AB
- 2. © 2019 Chemistry Matters Inc. Chemistry Matters Inc. Co-Authors Dr. Lisa Kates Dr. Phil Richards Michelle Misselwitz Acknowledgements 2 Mount Royal University Dr. Gwen O’Sullivan Nadin Bogelsak University of Alberta Dr. James Harynuk Dr. Paulina de la Mata PennState University Dr. Frank Dorman PITTCON 2019 Philadelphia
- 3. © 2019 Chemistry Matters Inc. Victoria, Australia Year: 2009 Causes: Arson, Lighting, Power Lines Fatalities: 173 Individuals Damage: Over 3,500 Buildings Destroyed Burned Area: 450,000 Hectares Attica, Greece Year: 2018 Causes: Suspected Arson Fatalities: 100 Individuals, 172 Injured Damage: Over 1,000 Buildings British Columbia, Canada Year: 2018 Causes: Human Cause and Lightning Fatalities: Unknown Damage: 50 Buildings Destroyed Burned Area: 1,350,000 Hectares Slave Lake, Alberta, Canada Year: 2011 Cause: Arson Fatalities: 1 Individual Damage: Over 500 Buildings Destroyed Or Damaged Burned Area: ~5,000 Hectares California, USA (Camp Fire) Year: 2018 Causes: Power Infrastructure, Negligence, Human Causes, Under Investigation Fatalities: ~90 Individuals Damage: ~19,000 Buildings Destroyed Burned Area: 62,000 Hectares Fort McMurray, Alberta, Canada Year: 2016 Causes: Suspected Human Cause, Under Investigation Fatalities: 2 Individuals Damage:~3,200 Buildings Destroyed Burned Area: 590,000 Hectares 2.5x for acres
- 4. © 2019 Chemistry Matters Inc. 4 History of 2DGC-TOFMS and Fire Debris Analysis • 1994 - ASTM E1618 first approved • 1994 - First reported use of MDGC for ILR (Jayatilaka & Poole) - Heart-cut, FID, simulated samples • 1996 - First conference report of GCxGC for ILR at Pittcon (Phillips et al.) • 2002 - First reported use of GCxGC-FID for ILR (Frysinger & Gaines) – simulated samples • In 2012, first known application of 2DGC-TOFMS to actual wildfire investigation (PennState University) • 2015 – CMI presented on application to real wildfire investigation for fire debris analysis at multidimensional chromatography workshop • In 2016, largest 2DGC-TOFMS application for wildfire debris analysis (UofAlberta) • 2017 and 2019 - CMI presented on use of 2DGC-TOFMS for fingerprinting ILRs on wildfire debris samples at multidimensional chromatography workshops • “GCxGC–TOFMS offers an extremely promising future in the field of fire debris analysis. It permits better separation, and, therefore, better specificity of the analysis of ILR. This will be the change of technique that will lead to a significant improvement of the analysis of fire debris samples in the future.” Stauffer, E., Newman, R., Dolan, JA. Handbook Fire Debris Analysis (2007) PITTCON 2019 Philadelphia
- 5. © 2019 Chemistry Matters Inc. 5 Steps Before the Lab PITTCON 2019 Philadelphia
- 6. © 2019 Chemistry Matters Inc. 6PITTCON 2019 Philadelphia Arson Investigations – Laboratory Perspective • Identify the presence or absence of ignitable liquid residue (ILR) in fire debris samples collected at suspected arson investigation 1. Extract fire debris samples (building materials or wood, soil, leaf litter) 2. Analyze extract for ILR 3. Identify presence/absence of ILR based on target compounds and extracted ion chromatograms 4. Identify type of ILR used • ILR can be any chemical substance that can ignite – Acetone, toluene – Lighter fluid, gasoline, diesel
- 7. © 2019 Chemistry Matters Inc. ASTM Extraction Method • Extraction is non-specific – no clean-up, need good chromatography 7 Heat volatilizes target compounds into headspace Carbon strip adsorbs compounds PITTCON 2019 Philadelphia • Add clean carbon strip, heat 50-80oC for 2-24 hours, elute with 50-1000 µL
- 8. © 2019 Chemistry Matters Inc. Identification of ILR by GC-MS 8 • ASTM E1618, developed primarily for structural fires • Reference chromatogram comparison to identify ILR type • Use extracted ion chromatograms to visually identify characteristic peaks/groups • Find “must have compounds”, peak list table (~40 compounds) PITTCON 2019 Philadelphia Three Musketeers C2-benzenes Castle Group C3-benzenes Gang of Four C4-benzenes Twin Towers C1-naphthalenes
- 9. © 2019 Chemistry Matters Inc. Limitations of ASTM Method E1618 for Wildfire Debris Analysis 9 • Very heavy focus on visual pattern matching to identify ILRs in samples • Uses limited number of marker compounds of common accelerants – Why be limited? There are 700-1500 compounds in gasoline • Dispersion of ignitable liquid higher in wildfire scenario – Need lower detection limits (10x lower with GCxGC-TOFMS – Abel et al. 2018) • More interference potential with wildfire debris – Need better chromatography Fire Debris Wildfire Debris PITTCON 2019 Philadelphia
- 10. © 2019 Chemistry Matters Inc. Three Musketeers C2-benzenes Castle Group C3-benzenes Gang of Four C4-benzenes 10PITTCON 2019 Philadelphia Gasoline - No Matrix
- 11. © 2019 Chemistry Matters Inc. Matrix - Burnt carpet and flooring + Gasoline 11PITTCON 2019 Philadelphia
- 12. © 2019 Chemistry Matters Inc. Pinene Limonene 4-isopropyl toluene secbutyl benzene Lots of natural chemicals, difficult to see gasoline pattern 12PITTCON 2019 Philadelphia Matrix – Vegetation + Gasoline
- 13. © 2019 Chemistry Matters Inc. 2DGC-TOFMS Eliminates Matrix Interferences 13 Looking for this - gasoline Wildfire debris sample – positive for gasoline PITTCON 2019 Philadelphia
- 14. © 2019 Chemistry Matters Inc. 14 GC-MS vs. 2DGC-TOFMS for ILR Detection • Retention time match • Mass spectral match • Lots of co-elution issues with matrix • Limited to target compounds in ASTM • Visual based for identification • Libraries and 25 years of experience • Two retention time matches • Higher mass spectral match factor (resolution of chromatography) • Can eliminate co-elution issues with matrix • Lower detection limits (10x, Abel et al. 2018) • Unlimited peak capacity and can expand targeted compound list (700-1500 compounds in gasoline) • Visuals not the same • Re-build libraries, new kid on the block Routine GC-MS 2DGC-TOFMS PITTCON 2019 Philadelphia
- 15. © 2019 Chemistry Matters Inc. Wildfire Investigation Samples – Suspected Arson • Samples submitted for ILR analysis from wildfire investigations • Positive bias for results, identified by accelerant detection canine (n = 164 samples) • Analyzed samples by routine GC-MS (ASTM E1618) and by 2DGC- TOFMS • Experiment included trip blanks (n=7) and comparison reference samples (n=15) • Used ASTM E1618 method target compounds only for identification of presence/absence of gasoline for both methods 15PITTCON 2019 Philadelphia
- 16. © 2019 Chemistry Matters Inc. 16PITTCON 2019 Philadelphia Method Comparison – Three Muskateers • Provides little value for identification of gasoline/ILRs – Detected in all samples • Background and trip blanks are an issue
- 17. © 2019 Chemistry Matters Inc. 17PITTCON 2019 Philadelphia Method Comparison – Castle Group + 1 • ”Must have compounds” almost 100% detection rate with 2DGC-TOFMS Castle Group
- 18. © 2019 Chemistry Matters Inc. 18PITTCON 2019 Philadelphia Method Comparison – Twin Towers • Substantial increase in detectability of methyl-naphthalenes • Lowest concentration in extracts due to volatility (extraction efficiency) and lowest abundance in gasoline
- 19. © 2019 Chemistry Matters Inc. 19 Conclusions PITTCON 2019 Philadelphia • Using 2DGC-TOFMS for ILR analysis increased detectability of gasoline in suspected arsonous wildfire investigations. – Decreased ‘tentative’ classification • Method is more sensitive and the resolution power of the chromatography makes identification of ILRs easier in high matrix samples, such as wildfire debris. • Missing a positive classification can have implications on prosecution outcomes n=164 suspected arson wildfire debris samples
- 20. © 2019 Chemistry Matters Inc. Thank you for your attention Contact Info: Chemistry Matters Inc. Court Sandau Cell: 403.669.8566 Email: csandau@chemistry-matters.com www.chemistry-matters.com Visit website and sign up with email to automatically receive CMI blogs. 20PITTCON 2019 Philadelphia