CFC Toxicology & Drug Analysis 5 — Questions and Answers
Question 1: Which phenomenon describes the increase in drug concentration within a specific organ or tissue relative to blood due to lipophilicity?
- First-pass metabolism
- Bioaccumulation (Correct answer)
- Tissue redistribution
- Enterohepatic recirculation
Correct answer: Bioaccumulation
Bioaccumulation (or tissue sequestration) occurs when lipophilic drugs concentrate in fatty tissues, leading to tissue-to-blood ratios greater than one.
Question 2: A forensic analyst tests a white powder using the Marquis reagent and observes a purple-to-black color change. This result is presumptive for:
- Cocaine hydrochloride
- Methamphetamine
- Opiates (morphine/heroin) (Correct answer)
- MDMA (ecstasy)
Correct answer: Opiates (morphine/heroin)
The Marquis reagent turns purple-to-black in the presence of opiates such as morphine and heroin, serving as a presumptive color test.
Question 3: In alcohol pharmacokinetics, what is the average elimination rate of ethanol from blood in a non-tolerant individual?
- 0.005–0.01 g/dL per hour
- 0.015–0.02 g/dL per hour (Correct answer)
- 0.05–0.08 g/dL per hour
- 0.10–0.15 g/dL per hour
Correct answer: 0.015–0.02 g/dL per hour
Ethanol follows zero-order kinetics in most people, with average elimination rates of approximately 0.015–0.02 g/dL per hour in non-tolerant individuals.
Question 4: Which metabolite confirms that a person consumed heroin rather than prescribed morphine or codeine?
- Morphine-3-glucuronide
- 6-Monoacetylmorphine (6-MAM) (Correct answer)
- Hydromorphone
- Normorphine
Correct answer: 6-Monoacetylmorphine (6-MAM)
6-Monoacetylmorphine (6-MAM) is a unique heroin metabolite not produced from morphine or codeine, definitively confirming heroin use when detected.
Question 5: A suspect claims their positive cocaine urine test resulted from handling currency. As a forensic consultant, how should this be evaluated?
- Accept the claim because currency is known to be heavily contaminated with cocaine
- Reject the claim because passive transfer from handling cocaine-contaminated currency does not produce urine benzoylecgonine above cutoff levels (Correct answer)
- Order additional hair testing to rule out passive exposure
- Recommend retesting with a lower cutoff threshold
Correct answer: Reject the claim because passive transfer from handling cocaine-contaminated currency does not produce urine benzoylecgonine above cutoff levels
Scientific studies consistently show that passive handling of cocaine-contaminated currency does not produce urine benzoylecgonine concentrations at or above immunoassay cutoff levels (150 ng/mL).
Question 6: Which class of synthetic drugs, often sold as 'bath salts,' primarily acts as catecholamine-releasing agents and reuptake inhibitors?
- Synthetic cannabinoids (K2/Spice)
- Synthetic cathinones (mephedrone, MDPV) (Correct answer)
- Novel psychoactive opioids (nitazenes)
- Piperazines (BZP, TFMPP)
Correct answer: Synthetic cathinones (mephedrone, MDPV)
Synthetic cathinones like mephedrone and MDPV act as potent monoamine releasers and reuptake inhibitors, producing stimulant effects similar to cocaine and methamphetamine.
Question 7: In forensic toxicology, what is the purpose of using a deuterium-labeled internal standard (e.g., morphine-d3) during LC-MS/MS analysis?
- To increase the mass resolution of the instrument
- To correct for matrix-induced ionization suppression and extraction variability (Correct answer)
- To extend the calibration range of the assay
- To serve as a positive quality control for method validation
Correct answer: To correct for matrix-induced ionization suppression and extraction variability
Stable isotope-labeled internal standards co-elute with the analyte and experience identical matrix effects and extraction losses, allowing accurate quantitative correction.
CFC Toxicology & Drug Analysis 5
Which phenomenon describes the increase in drug concentration within a specific organ or tissue relative to blood due to lipophilicity?