Pyrolysis Products
Definition
Hydrocarbons released when synthetic substrates (polyurethane foam, carpet, vinyl flooring) burn or smoulder. They overlap the petroleum range and are the main interference in fire-debris analysis.
- Source
- Burning or smouldering synthetic substrates
- Examples of substrates
- Polyurethane foam, carpet, vinyl flooring
- Interference type
- Overlaps petroleum accelerant hydrocarbon range
- Field affected
- Fire-debris and accelerant analysis
Common questions
How do analysts tell pyrolysis products apart from an ignitable liquid residue?+
They compare the debris chromatogram's peak pattern against a substrate-only control burn of the same material where an accelerant is not present, and look for characteristic ignitable-liquid features such as a full homologous carbon-number series that background pyrolysis rarely reproduces cleanly.
Why does carpet debris create particular difficulty in fire-debris casework?+
Carpet backing and padding are often synthetic petroleum-derived polymers, so their pyrolysis products span the same carbon-number range as common accelerants like gasoline or diesel, making a negative or ambiguous chromatogram result harder to interpret with confidence.
Does the presence of pyrolysis products rule out an accelerant in a sample?+
No. Pyrolysis products and an ignitable liquid can be present in the same debris sample simultaneously, so their overlap only complicates interpretation and does not itself confirm or exclude an accelerant.
Related terms
- ASTM E1387 / E1618
- ASTM standards for ignitable-liquid residue analysis. E1387 was the older colour-coded scheme; E1618 (current) defines the modern eight-class system based on GC-MS...
- Extracted Ion Profile (EIP)
- A GC-MS chromatographic display plotting only ions of a specified m/z value against retention time, effectively filtering out all compounds that do...
- Ignitable Liquid
- In fire debris analysis, any flammable liquid that could serve as an accelerant. E1618 classifies ignitable liquids into eight categories based on...
- Passive Headspace Charcoal-Strip Extraction
- ASTM E1412 method. Fire debris is sealed in an unlined metal can with a suspended activated-charcoal strip, heated to 60 to 80...
- Petroleum Fractions
- Crude-oil distillation cuts ordered by boiling range: light (C4 to C9, pentane, hexane, naphtha), medium (C8 to C12, mineral spirits, kerosene), heavy...
- SPME
- Solid-phase microextraction. A polymer-coated fused-silica fibre (typically PDMS or PDMS-DVB) is exposed to vial headspace, then thermally desorbed in the GC injector....
- Weathering
- Loss of lighter components from an ignitable liquid by evaporation during and after the fire. Weathered gasoline loses C4 to C7 first;...