Weathering
Definition
Loss of lighter components from an ignitable liquid by evaporation during and after the fire. Weathered gasoline loses C4 to C7 first; the C9 to C12 alkylbenzene envelope persists and remains diagnostic.
- Definition
- Loss of lighter components from an ignitable liquid by evaporation
- First lost
- C4 to C7 range
- Persists longest
- C9 to C12 alkylbenzene envelope
- Occurs during
- The fire and afterward, before sampling
Common questions
Why does weathering matter to identifying an ignitable liquid in fire debris?+
A heavily weathered gasoline sample loses much of its light-end signature, so the chromatogram looks different from a fresh gasoline standard. Analysts rely on the surviving heavier alkylbenzene pattern rather than the full original profile to make the identification.
Does weathering ever make it impossible to identify an ignitable liquid?+
Severe weathering can strip enough components that pattern recognition becomes uncertain, particularly for lighter petroleum products. In such cases the diagnostic alkylbenzene envelope and target-compound ratios carry most of the identification weight.
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...
- Pyrolysis Products
- Hydrocarbons released when synthetic substrates (polyurethane foam, carpet, vinyl flooring) burn or smoulder. They overlap the petroleum range and are the main...
- 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....