CFI Accelerant Detection & Fire Debris Analysis 1 — Questions and Answers
Question 1: Which analytical method is considered the gold standard for identifying ignitable liquid residues in fire debris laboratory samples?
- Gas chromatography-mass spectrometry (GC-MS) (Correct answer)
- Thin-layer chromatography (TLC)
- Infrared spectroscopy (IR)
- X-ray fluorescence (XRF)
Correct answer: Gas chromatography-mass spectrometry (GC-MS)
GC-MS is the accepted gold standard because it separates compounds by boiling point and identifies them by molecular weight, providing a definitive chemical fingerprint.
Question 2: What does an alert from an accelerant detection canine (ADC) at a fire scene indicate to the investigator?
- A confirmed arson fire has occurred
- The potential presence of ignitable liquid residues requiring sample collection (Correct answer)
- The exact pour pattern of the accelerant
- The identity of the accelerant used
Correct answer: The potential presence of ignitable liquid residues requiring sample collection
A canine alert indicates the potential presence of ignitable liquid residues and should prompt sample collection, but does not by itself confirm arson.
Question 3: Which collection method is most widely used for extracting ignitable liquid residues from fire debris samples in the laboratory?
- Water extraction with solvent wash
- Passive headspace concentration using activated charcoal strips (Correct answer)
- Steam distillation under vacuum
- Acid digestion followed by solvent rinse
Correct answer: Passive headspace concentration using activated charcoal strips
Passive headspace concentration with activated charcoal strips captures volatile ignitable liquid residues from the air space above the debris without disturbing the sample.
Question 4: According to ASTM E1618, into how many categories are ignitable liquids classified for fire debris analysis?
- 5
- 8
- 10 (Correct answer)
- 12
Correct answer: 10
ASTM E1618 classifies ignitable liquids into 10 categories based on chemical composition and chromatographic profiles, including gasoline, petroleum distillates, and oxygenated solvents.
Question 5: What effect does firefighting water application typically have on ignitable liquid accelerant evidence?
- It completely destroys all ignitable liquid residues
- It has no measurable effect on accelerant evidence
- It can dilute but may not eliminate ignitable liquid residues trapped in substrates (Correct answer)
- It chemically neutralizes all hydrocarbon compounds
Correct answer: It can dilute but may not eliminate ignitable liquid residues trapped in substrates
Water dilutes accelerant residues but heavier petroleum products bind to substrates and often survive water application, remaining detectable by laboratory analysis.
Question 6: Which type of burn pattern is most commonly associated with a poured ignitable liquid accelerant on a floor?
- High V-pattern centered on a wall outlet
- Irregular low burn patterns with defined edges at floor level (Correct answer)
- Inverted cone pattern extending from the ceiling downward
- Uniform char pattern consistent with natural fuel load
Correct answer: Irregular low burn patterns with defined edges at floor level
Poured ignitable liquids pool on the floor and burn with irregular, low-level patterns that have defined edges corresponding to where the liquid spread.
Question 7: What is the recommended container for collecting fire debris samples destined for ignitable liquid residue analysis?
- Sealed plastic zip-lock evidence bags
- Paper grocery bags with evidence tape
- New, unlined metal paint cans or nylon oven bags (Correct answer)
- Glass mason jars with rubber-sealed lids
Correct answer: New, unlined metal paint cans or nylon oven bags
New, unlined metal cans and nylon oven bags are impermeable to ignitable liquid vapors and free of background contamination, making them the accepted standard containers.
CFI Accelerant Detection & Fire Debris Analysis 1
Which analytical method is considered the gold standard for identifying ignitable liquid residues in fire debris laboratory samples?