Valid internal standard technique for arson detection based on gas chromatography-mass spectrometry

Area of Science:

• Forensic Science
• Analytical Chemistry

Background:

• Standard methods for accelerant detection in fire debris include ASTM E1412-07 and E1618-10.
• Critical stages involve sample conservation, accelerant extraction to activated charcoal strips (ACS), solvent extraction, and gas chromatography-mass spectrometry (GC-MS) analysis.

Purpose of the Study:

• To propose a quality control (QC) strategy for validating fire debris analysis.
• To ensure the reliability of sample conservation, accelerant residue transfer, and GC-MS analysis.

Main Methods:

• Utilized internal standard additions with compounds of varying volatility.
• Applied QC parameters to assess sample conservation, ACS extraction, and GC-MS performance.
• Developed QC parameters independent of GC-MS sensitivity and ACS saturation effects.

Main Results:

• The proposed QC strategy effectively monitors sample conservation, accelerant extraction, and GC-MS repeatability.
• QC parameters demonstrated negligible uncertainty from standard additions.
• Observed dispersion of QC parameters was suitable for their intended application.

Conclusions:

• The developed QC procedure is adequate for ensuring the quality of fire debris analysis.
• Internal standard additions provide a robust method for validating critical analytical stages.
• This approach enhances the reliability of accelerant residue detection in forensic investigations.