Detection of l-Methamphetamine and l-Amphetamine as Selegiline Metabolites.

Selegiline is a selective, irreversible monoamine oxidase-B inhibitor, used for reducing symptoms in early-stage Parkinson's disease. The metabolites of selegiline include l-methamphetamine, l-amphetamine, and desmethylselegiline. The stereoisomers of selegiline metabolites, d-methamphetamine and d-amphetamine, are highly addictive psychostimulants and some of the most abused drugs in South Korea. In order to differentiate medical selegiline users form illicit methamphetamine abusers, it is important to distinguish between the l-isomers and d-isomers in urine samples. A 52-year-old male, seemingly under the influence of intoxication and demonstrating abnormal behavior, was reported to the police. The initial urine test using a methamphetamine detection kit demonstrated a positive result. Given the initial results, the police officer requested a further analysis of the urine sample. The urine sample was screened using headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Both methamphetamine and amphetamine were detected, in addition to selegiline and desmethylselegiline. To quantitate methamphetamine and amphetamine by HS-SPME-GC-MS, we performed a standard addition method due to the matrix effect of the case sample. Consistent with previous studies, our results indicated that the ratio of amphetamine to methamphetamine was 0.27, which was in the range of selegiline ingestion. Furthermore, we confirmed l-methamphetamine and l-amphetamine by chiral derivatization using (R)-(-)-α-methoxy-α-(trifluoromethyl) phenylacetyl chloride.