Toxicology & Drug Analysis Flashcards
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Read the first 7 Toxicology & Drug Analysis flashcards as text
Which analytical technique is considered the gold standard for confirming the identity of an unknown drug in forensic toxicology?
Answer: Gas chromatography-mass spectrometry (GC-MS)
GC-MS combines separation with definitive molecular identification and is universally accepted as the confirmatory gold standard in forensic drug analysis.
A victim's blood sample shows elevated carboxyhemoglobin levels. What toxicant is most likely responsible?
Answer: Carbon monoxide
Carbon monoxide binds hemoglobin to form carboxyhemoglobin, and elevated levels (>10%) are diagnostic of CO exposure.
In postmortem redistribution, drug concentrations in which specimen are most affected by site-dependent changes?
Answer: Central blood (cardiac)
Central blood from the heart and great vessels is most susceptible to postmortem redistribution due to proximity to drug-rich organs like the liver and lungs.
Which enzyme immunoassay cross-reacts most problematically with over-the-counter cold medications to produce false-positive amphetamine screens?
Answer: Ephedrine and pseudoephedrine
Ephedrine and pseudoephedrine share structural similarity with amphetamines and frequently cause false-positive immunoassay screens for amphetamines.
What is the primary metabolite of cocaine detected in urine drug screens?
Answer: Benzoylecgonine
Benzoylecgonine is the major urinary metabolite of cocaine, persisting 2–4 days after use and targeted by immunoassay screens.
A forensic toxicologist discovers that a decedent's vitreous ethanol is significantly higher than their peripheral blood ethanol. What does this most likely indicate?
Answer: Active alcohol absorption at the time of death
When vitreous ethanol exceeds blood ethanol, it suggests the decedent was in the absorption phase, with blood-alcohol still rising at the time of death.
Which pharmacokinetic parameter describes the volume of fluid a drug appears to occupy in the body relative to plasma concentration?
Answer: Volume of distribution (Vd)
Volume of distribution (Vd) relates the total amount of drug in the body to its plasma concentration, reflecting tissue binding and distribution.