Enantiomeric profiling of amphetamines in wastewater using chiral derivatisation with gas chromatographic-tandem mass spectrometric detection.

Enantiomeric profiling can supplement wastewater-based epidemiology (WBE) by providing additional information on drug origin (licit or illicit), improving consumption estimates, i.e., differentiating between disposal and consumption, and offering an insight into the potency of drugs available on the illicit drug market. We report on the enantiomeric profiling of amphetamines in wastewater using R(-)-α-methoxy-α-(trifluoromethyl) phenylacetyl chloride (R-MTPCl), a chiral derivatising agent and GC-MS/MS. The method performed well when evaluated against the SANTE/12682/2019 guidelines in terms of recovery (81-99%), accuracy (99-111%), repeatability (1-8%RSD) and linearity (LOQ-1000 ng/mL). The LOD and LOQ were 120 ng/L and 400 ng/L, respectively. The method was applied to samples of raw wastewater from two Slovene municipalities with unusual levels of amphetamines: Ljubljana (LJ1) and Velenje (VE1). LJ1 had an anomalously high mass load of MDMA (3,4-methylenedioxymethamphetamine) identified during SCORE 2020, and VE1 is a representative sample of the consistently high mass load of amphetamine. A second Ljubljana sample (LJ2) was chosen as a representative sample. The presence of racemic MDMA (EF = 0.511) in LJ1 indicated the disposal of the unused drug into the sewer, while the enrichment of R-MDMA (EF = 0.666) in the combined extract sample from Ljubljana (LJ2) indicated consumption. In the case of Velenje and Ljubljana, it is impossible to distinguish between the direct disposal and consumption of amphetamine and methamphetamine. Also, since amphetamine/methamphetamine-based prescription medications are unavailable in Slovenia, racemic amphetamine in VE1 (EF = 0.514) and LJ2 (EF = 0.459) indicate racemic and the more potent S-amphetamine are sold on the illicit drug market. Only S-methamphetamine was detected in wastewater (LJ2: EF = 0), indicating the presence of only the more potent S-methamphetamine on the illicit drug market. Overall, enantiomeric profiling provided useful information on amphetamine residues. In addition, chiral derivatisation can be a cost-effective alternative to using chiral chromatographic columns for the enantiomeric profiling of amphetamines in wastewater.