Accelerant Detection & Fire Debris Analysis Flashcards
7 cards from real CFI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Accelerant Detection & Fire Debris Analysis flashcards as text
In fire debris analysis, 'weathering' of an ignitable liquid refers to which process?
Answer: Preferential evaporation of lighter volatile components over time, altering the chromatographic profile
Weathering is the loss of lighter, more volatile fractions through evaporation, which changes the relative ratios of compounds and can make identification more challenging.
Which of the following is NOT a common source of background interference when analyzing fire debris samples for ignitable liquids?
Answer: Atmospheric nitrogen present in the sample container
Atmospheric nitrogen is chemically inert and does not produce hydrocarbon signals; pyrolysis products, petroleum materials, and firefighting agents can all create interference.
What is 'matrix interference' in the context of fire debris laboratory analysis?
Answer: Chromatographic signals from burned substrate materials that can resemble ignitable liquid residues
Matrix interference occurs when pyrolysis products of burned materials such as carpet, foam, or wood produce chemical patterns that overlap with or mimic accelerant signatures.
What is the purpose of including a 'blank' container in a fire debris laboratory analysis submission?
Answer: To confirm that the collection containers themselves are free of contamination
A blank container of the same type used for evidence collection confirms that the containers introduce no background contamination, protecting the integrity of results.
At approximately what concentration level can well-trained accelerant detection canines detect ignitable liquid residues?
Answer: Parts per trillion (ppt)
Accelerant detection canines can detect ignitable liquid residues at parts per trillion concentrations, making them far more sensitive than most electronic vapor detectors.
Which ASTM standard specifically governs the forensic analysis of fire debris samples by gas chromatography-mass spectrometry?
Answer: ASTM E1618
ASTM E1618 is the standard test method that defines procedures and classification criteria for analyzing fire debris by GC-MS to identify ignitable liquid residues.
In GC-MS fire debris analysis, what is the significance of identifying a 'target compound' in a sample?
Answer: It indicates the presence of a specific class of ignitable liquid within the sample
Target compounds are chemical markers that help classify the type or class of ignitable liquid present; they do not alone prove arson or identify a specific source.