Extracted Ion Profile (EIP)
Definition
A GC-MS chromatographic display plotting only ions of a specified m/z value against retention time, effectively filtering out all compounds that do not produce that ion. Used in ASTM E1618 to isolate aromatic compounds (m/z 91, 105, 119) and n-alkanes (m/z 57) from complex fire debris matrices.
- Technique
- Chromatographic filtering by mass-to-charge ratio on GC-MS data
- Primary use
- Isolating accelerants from complex fire debris matrices
- Standard method
- ASTM E1618 pattern recognition
Common questions
What does an extracted ion profile do in fire debris analysis?+
An EIP filters a GC-MS chromatogram to show only ions at a specific m/z value, effectively removing background noise from pyrolysis and other non-target compounds. This lets an analyst see accelerant signals that would otherwise be buried in a complex spectrum.
What m/z values are used to identify common accelerants?+
Alkylbenzenes show up at m/z 91, 105, and 119. Naphthalenes appear at 128, 142, and 156. Normal alkanes produce ions at m/z 57, 71, and 85. Analysts select the most diagnostic ions for their target compounds to build a cleaner chromatographic picture.
Why is EIP part of the ASTM E1618 standard?+
E1618 uses EIP as a pattern recognition tool to isolate compound classes from fire debris matrices that contain a large number of compounds from pyrolysis and other sources. By filtering to specific ions, an analyst can reliably identify the presence of accelerants without being overwhelmed by the fire's own thermal degradation products.
Related terms
- ASTM E1618
- Standard Test Method for Ignitable Liquid Residues in Extracts from Fire Debris Samples by Gas Chromatography-Mass Spectrometry. The active analytical standard defining...
- Ignitable Liquid
- In fire debris analysis, any flammable liquid that could serve as an accelerant. E1618 classifies ignitable liquids into eight categories based on...
- Unresolved Complex Mixture (UCM)
- The broad hump of hundreds of co-eluting cycloalkane and isoalkane compounds in the TIC of heavy petroleum products (diesel, heavy fuel oil,...
- 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...
- Carbon Disulfide (CS2)
- The standard elution solvent for activated charcoal strips in ASTM E1412 passive headspace analysis. Selected for its low UV absorption, minimal GC-FID...
- DB-5 Column
- A gas chromatography capillary column with a 5% phenyl-95% dimethylpolysiloxane stationary phase, the standard column for fire debris GC-MS analysis. Provides adequate...
- Evaporative Weathering
- The preferential loss of volatile components (benzene, toluene, C5-C7 alkanes) from an ignitable liquid residue during and after a fire, altering the...
- Ignitable Liquid Reference Collection (ILRC)
- A database of GC-MS chromatographic data for over 1,100 ignitable liquid products maintained by the National Centre for Forensic Science at the...
- Isoparaffinic Products
- An E1618 category of ignitable liquid dominated by branched-chain (isoparaffinic) alkanes with minimal aromatic or n-alkane content. Examples include Isopar solvents and...
- Light Petroleum Distillate (LPD)
- The ASTM E1618 ignitable liquid class covering C4-C9 aliphatic products (charcoal lighter fluid, camping fuel, some paint thinners). The class most frequently...
- OSAC (Fire and Explosion)
- Organisation of Scientific Area Committees, Fire and Explosion Investigation Subcommittee, under NIST. Develops and publishes standards and needs statements for fire investigation...
- 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...
Explained in these topics
- Accelerant Detection: ASTM E1387 / E1618 and Passive Headspace ConcentrationA GC-MS chromatographic display plotting only ions of a specified m/z value against retention time, effectively filtering out all compounds that do not produce...
- Analysis of Petroleum Products and Fire AccelerantsIons chosen from a GC-MS scan to highlight specific compound classes: alkylbenzenes (m/z 91, 105, 119), naphthalenes (128, 142, 156), n-alkanes (57, 71, 85). E...
- Fire Debris Analysis: GC-MS and ASTM E1618 Pattern RecognitionA chromatographic trace reconstructed from the full-scan mass spectrum data by plotting signal intensity at a single selected m/z value across retention time....