CFI Accelerant Detection & Fire Debris Analysis 2

Question 1

In fire debris analysis, 'weathering' of an ignitable liquid refers to which process?

Accepted Answer

Preferential evaporation of lighter volatile components over time, altering the chromatographic profile

Answer

Weathering is the loss of lighter, more volatile fractions through evaporation, which changes the relative ratios of compounds and can make identification more challenging.

Question 2

Which of the following is NOT a common source of background interference when analyzing fire debris samples for ignitable liquids?

Accepted Answer

Atmospheric nitrogen present in the sample container

Answer

Atmospheric nitrogen is chemically inert and does not produce hydrocarbon signals; pyrolysis products, petroleum materials, and firefighting agents can all create interference.

Question 3

What is 'matrix interference' in the context of fire debris laboratory analysis?

Accepted Answer

Chromatographic signals from burned substrate materials that can resemble ignitable liquid residues

Answer

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.

Question 4

What is the purpose of including a 'blank' container in a fire debris laboratory analysis submission?

Accepted Answer

To confirm that the collection containers themselves are free of contamination

Answer

A blank container of the same type used for evidence collection confirms that the containers introduce no background contamination, protecting the integrity of results.

Question 5

At approximately what concentration level can well-trained accelerant detection canines detect ignitable liquid residues?

Accepted Answer

Parts per trillion (ppt)

Answer

Accelerant detection canines can detect ignitable liquid residues at parts per trillion concentrations, making them far more sensitive than most electronic vapor detectors.

(CFI) Certified Fire Investigator Practice Test

(CFI) Certified Fire Investigator Practice Test

CFI Accelerant Detection & Fire Debris Analysis 2