ABT Forensic Toxicology 1 — Questions and Answers
Question 1: In postmortem toxicology, which phenomenon describes the redistribution of drugs from concentrated tissues (liver, lung) into blood after death?
- Hepatic first-pass effect
- Postmortem redistribution (PMR) (Correct answer)
- Autolysis-mediated degradation
- Putrefactive synthesis
Correct answer: Postmortem redistribution (PMR)
Postmortem redistribution (PMR) occurs when drugs diffuse from high-concentration organs into adjacent blood vessels after death, elevating postmortem blood concentrations.
Question 2: Which matrix is preferred for documenting historical drug exposure over weeks to months in forensic investigations?
- Blood
- Urine
- Hair (Correct answer)
- Vitreous humor
Correct answer: Hair
Hair provides a chronological record of drug incorporation, with approximately 1 cm of hair growth representing one month of exposure history.
Question 3: Chain of custody in forensic toxicology is essential primarily to:
- Ensure specimen temperature is maintained during transport
- Document sample handling to preserve legal admissibility of results (Correct answer)
- Prevent evaporation of volatile analytes
- Satisfy CLIA laboratory certification requirements only
Correct answer: Document sample handling to preserve legal admissibility of results
Chain of custody documentation tracks every person who handles a forensic specimen, ensuring results are legally defensible and specimens have not been tampered with.
Question 4: Vitreous humor is a preferred postmortem specimen for ethanol analysis because it:
- Contains higher ethanol concentrations than blood
- Is less subject to postmortem ethanol production by microorganisms (Correct answer)
- Provides the longest window of detection for alcohol
- Is easier to collect than peripheral blood
Correct answer: Is less subject to postmortem ethanol production by microorganisms
Vitreous humor is an isolated compartment relatively protected from bacterial contamination and postmortem fermentation, giving more reliable postmortem ethanol results.
Question 5: Which confirmatory analytical technique is considered the 'gold standard' for forensic drug identification?
- Immunoassay (ELISA)
- Gas chromatography-mass spectrometry (GC-MS) (Correct answer)
- High performance liquid chromatography (HPLC-UV)
- Thin-layer chromatography (TLC)
Correct answer: Gas chromatography-mass spectrometry (GC-MS)
GC-MS provides both chromatographic retention time and a mass spectrum that serves as a molecular fingerprint, making it the forensic gold standard for definitive drug identification.
Question 6: In driving under the influence (DUI) cases, the per se legal limit for blood alcohol concentration (BAC) for non-commercial drivers in all US states is:
- 0.05 g/dL
- 0.08 g/dL (Correct answer)
- 0.10 g/dL
- 0.02 g/dL
Correct answer: 0.08 g/dL
All US states have adopted 0.08 g/dL (80 mg/dL) as the per se legal BAC limit for non-commercial adult drivers following federal highway funding incentives.
ABT Forensic Toxicology 1
In postmortem toxicology, which phenomenon describes the redistribution of drugs from concentrated tissues (liver, lung) into blood after death?