Chirality of methamphetamine and amphetamine from workplace urine samples

Area of Science:

• Forensic Chemistry
• Analytical Chemistry
• Toxicology

Background:

• Methamphetamine and amphetamine are chiral drugs, existing as different stereoisomers (d- and l-isomers).
• The chirality of these substances can provide insights into their origin, whether synthesized or derived from specific pharmaceutical products.
• Previous analyses have focused on identifying the presence of these drugs, but detailed chiral analysis is crucial for comprehensive forensic evaluation.

Purpose of the Study:

• To determine the specific chirality (stereoisomer composition) of methamphetamine and amphetamine detected in positive urine samples.
• To investigate potential correlations between observed chirality and drug origin or manufacturing processes.
• To differentiate between illicitly synthesized drugs and those potentially sourced from over-the-counter medications.

Main Methods:

• Reexamination of positive methamphetamine/amphetamine urine samples.
• Preparation of (S)-N-(Trifluoroacetyl)prolyl derivatives of the target analytes.
• Analysis of the prepared derivatives using Gas Chromatography-Mass Spectrometry (GC/MS) for chiral separation and identification.

Main Results:

• One sample contained exclusively d-isomers of both methamphetamine and amphetamine.
• Most samples with both drugs exhibited skewed racemates, with a slight predominance of l-methamphetamine and d-amphetamine.
• Samples containing only amphetamine showed a 50:50 mixture of d- and l-isomers. Pure l-methamphetamine, typically associated with Vicks VapoInhaler, was not detected in any sample.

Conclusions:

• The chiral analysis of methamphetamine and amphetamine in urine provides valuable forensic information beyond simple detection.
• The observed isomer distributions suggest specific synthetic routes or sources for the detected drugs.
• The absence of pure l-methamphetamine indicates that the Vicks VapoInhaler was not a source in these particular cases.