Applying the Technology of the TurboMatrix 650 ATD to the Analysis of Liquid Accelerants in Arson Investigation

Significance of the Topic

Arson investigations rely on identifying liquid accelerants to determine if a fire was intentionally set. Gas chromatography combined with mass spectrometry offers distinctive hydrocarbon fingerprinting and spectral confirmation, ensuring reliable and legally defensible results.

Study Objectives and Overview

This application study evaluates a solvent free sampling approach using dynamic headspace extraction and automated thermal desorption. The goal is to enable multiple analyses and archiving from a single sample tube by coupling the TurboMatrix 650 ATD with the Clarus 600 GC/MS system. Weathered gasoline standards and controlled fire debris samples were analyzed to demonstrate method performance.

Methodology and Instrumentation

Sample preparation followed ASTM E1387 guidelines. Debris samples were heated to 80 °C and purged with clean air onto Tenax TA adsorbent tubes. Thermal desorption was conducted at 250 °C in a two stage desorb and re collect mode, splitting 49 mL/min back for reanalysis and 1 mL/min to the Elite-1MS GC column. The GC oven ramped from 35 °C to 280 °C at 15 °C/min over a 20 min run. The mass spectrometer scanned m/z 30–500 at four scans per second. All analyses used the TurboMatrix 650 ATD and Clarus 600 GC/MS platform.

Results and Discussion

Total ion chromatograms of unweathered versus weathered gasoline revealed that volatile alkylbenzenes dominate fresh samples, whereas heavier naphthalenes prevail after extensive weathering. Controlled fire debris without accelerant showed only background hydrocarbons, while samples with gasoline produced the characteristic fingerprint even at high split ratios. Sample re-collection allowed up to fifteen reproducible analyses from a single tube, maintaining consistent accelerant profiles and optimizing split ratios to prevent detector overload.

Benefits and Practical Applications

• Eliminates solvents, reducing disposal costs and analyst exposure
• High sensitivity and clean extraction improve detection of trace accelerants
• Sample re-collection enables confirmatory analyses and long term archiving
• Automated workflow enhances laboratory throughput and reproducibility

Future Trends and Potential Applications

Integration of high resolution mass spectrometry and chemometric algorithms could automate fingerprint recognition. Portable and miniaturized thermal desorption GC/MS systems may facilitate on site screening. New adsorbent materials with enhanced water tolerance will broaden the range of detectable compounds in complex fire debris matrices.

Conclusion

Dynamic headspace sampling combined with automated thermal desorption and GC/MS offers a robust, solvent free approach for forensic accelerant analysis. It delivers reproducible fingerprints, supports multiple analyses from a single tube, and aligns with ASTM standard practices for defensible results.

Reference

• ASTM Method E1387 Standard Test Method for ignitable liquid residues in fire debris by gas chromatography
• Bertsch W Zhang Q Sample preparation for chemical analysis of debris in suspect arson cases Analytica Chimica Acta 1990 236 183 95