Deck 11: Fire Investigation and Fire Debris Analysis

Question 1

What is the difference between an intentional fire and an arson fire?

A) nothing; they mean the same thing
B) arson implies criminal intent
C) intentional fires can also be accidental
D) arson fires can also be accidental
E) none of the above

Answer 1

B

Question 2

The primary job of a forensic chemist in a fire investigation is laboratory analysis to detect

A) any indication of electrical malfunctions
B) if a flammable mixture existed
C) ignitable liquid residues (ILR)
D) evidence of burn patterns
E) none of the above

Answer 2

C

Question 3

In most ILR analyses, any residues detected are classified if possible as

A) gasoline or something else
B) LPD, MPD, or HPD
C) gasoline, kerosene, or diesel
D) volatile or semivolatile
E) none of the above

Answer 3

B

Question 4

Currently, the most common method of sample preparation used in fire debris analysis is

A) SPME
B) automated thermal desorption
C) bulk solvent extraction
D) activated charcoal strips
E) none of the above

Question 5

If fire debris or an ACS used during headspace extraction is extracted with the n-alkane pentane, which group of compounds are most likely to be missed?

A) polar oxygenated species
B) aromatics
C) other alkanes
D) heavier hydrocarbons
E) none of the above

Question 6

The mass spectra of alkanes typically shows fragmentation and loss of successive units with m/z values of 14. This loss corresponds to

A) -CH2-
B) -N-
C) -C-H-H
D) -Li-Li-
E) none of the above

Question 7

One technique widely used to find classes of compounds within a GC-MS file of an ignitable liquid is/are

A) combined ion subtraction
B) alkane boxing
C) retention index filtering
D) extracted ion profiles
E) none of the above

Question 8

Why is it critical to collect background and matrix samples for fire debris analysis?

A) to have extra samples just in case
B) for examination of burn and wear patterns
C) many common materials are made with petroleum products
D) it is customary to always collect at least three samples
E) none of the above

Question 9

Which compounds in ILR are the most subject to weathering

A) the most volatile
B) the least volatile
C) alcohols and ethers
D) aromatics
E) none of the above

Question 10

A sample of fire debris contains small drops of visible liquid residues along with the burned debris. If the liquid represents ILR, we expect this liquid to contain

A) more of the lighter components than a fresh sample
B) more of the heavier components than a fresh sample
C) none of the oxygenated compounds that would be found in a fresh sample
D) none of the aromatic compounds that would be found in a fresh sample
E) none of the above

Question 11

Microbial degradation of ILR differs from weathering in that

A) the heavier compounds tend to be degraded more than the lighter compounds
B) weathering can only occur at high temperatures
C) there is no correlation with the volatility of the components
D) microbial degradation is fast compared to weathering
E) none of the above

Question 12

Blood from fire victims is tested for CO. However, simple combustion assumes that the only products formed are CO₂ and water. Where does the CO come from?

A) Inefficient combustion processes
B) breakdown of CO₂ at high temperatures
C) oxidation of char
D) conversion of CO₂ to CO in the lungs
E) none of the above

Question 13

What is/are the source(s) of HCN in fires?

A) nitrogen containing materials
B) paints
C) poorly stored chemical stocks
D) atmospheric nitrogen
E) none of the above

Question 14

What is the mechanism of toxicity of CO?

A) it interferes with energy production in the mitochondria
B) it causes hemoglobin to break down
C) it binds strongly to hemoglobin, blocks oxygen from binding, and causes oxygen depletion
D) it cause the formation of sulfhemoglobin
E) none of the above