CFPN Toxicology and Pharmacology in Forensic Cases 1 — Questions and Answers
Question 1: Which analytical method is considered the gold standard for confirming positive drug screening results in forensic toxicology?
- Gas chromatography–mass spectrometry (GC-MS) (Correct answer)
- Immunoassay
- Thin-layer chromatography
- High-performance liquid chromatography (HPLC) alone
Correct answer: Gas chromatography–mass spectrometry (GC-MS)
GC-MS provides definitive identification and quantification of substances, making it the confirmatory gold standard.
Question 2: A drug that has a half-life of 4 hours will be reduced to approximately what percentage of its original concentration after 12 hours?
- 12.5% (Correct answer)
- 25%
- 50%
- 75%
Correct answer: 12.5%
After three half-lives (4 × 3 = 12 hours), a drug is reduced to (0.5)³ = 12.5% of its original concentration.
Question 3: Which specimen provides the longest detection window for most drugs of abuse in forensic testing?
- Hair (Correct answer)
- Urine
- Blood
- Saliva
Correct answer: Hair
Hair retains drug metabolites for months, providing the longest detection window compared to other biological specimens.
Question 4: Benzodiazepines are typically detectable in urine for how long after therapeutic use?
- 3–7 days for short-acting; up to 6 weeks for long-acting (Correct answer)
- 12–24 hours for all types
- 1–3 days for all types
- 1–3 months for all types
Correct answer: 3–7 days for short-acting; up to 6 weeks for long-acting
Detection windows vary significantly between short-acting and long-acting benzodiazepines based on their metabolites and half-lives.
Question 5: What is the primary metabolite of cocaine that is detected in forensic urine drug screens?
- Benzoylecgonine (Correct answer)
- Ecgonine methyl ester
- Norcocaine
- Cocaethylene
Correct answer: Benzoylecgonine
Benzoylecgonine is the major urinary metabolite of cocaine and the target analyte in standard immunoassay screens.
Question 6: Which factor can cause a false-positive result for amphetamines on an immunoassay drug screen?
- Use of pseudoephedrine-containing cold medications (Correct answer)
- Caffeine consumption
- High vitamin C intake
- Ibuprofen use
Correct answer: Use of pseudoephedrine-containing cold medications
Pseudoephedrine has structural similarities to amphetamines and can cross-react with immunoassay antibodies.
CFPN Toxicology and Pharmacology in Forensic Cases 1
Which analytical method is considered the gold standard for confirming positive drug screening results in forensic toxicology?