Adam Erik Bauer and Arndís Sue Ching Löve
Introduction
Methylphenidate has been predominantly used to treat attention-deficit hyperactivity disorder (ADHD) in Iceland. In the last 4 years, a change in prescription patterns has been observed, with the use of lisdexamfetamine increasing to 37% of all prescribed ADHD medications. Lisdexamfetamine is a prodrug that is metabolized to (S)-amphetamine in blood whereas illegal amphetamine a racemic mixture of the two enantiomers, (R)- and (S)-amphetamine. Therefore, the detection of (R)-amphetamine in wastewater indicates illicit use of the drug.
Methods
Sample collection took place in May and December of 2023 for 7 consecutive days in one wastewater treatment plant that contributes to approximately half of the Reykjavík metropolitan area. Amphetamine was analyzed in wastewater using solid phase extraction and quantified using UPLC-MS/MS.
Results
Quantitative results showed that in May 2023, the amphetamine concentration was highest on Friday and Saturday and lowest on Monday. The results for December show that the concentration was lowest during the days leading up to New Year’s Eve. Chiral separation successfully resolved (R)-amphetamine and (S)-amphetamine in wastewater, enabling the calculation of enantiomeric fractions for each day. (R) amphetamine content fluctuated between 40% and 84% depending on the weekday. Weekdays generally showed a lower fraction of (R)-amphetamine, whereas weekends and holidays displayed the highest fractions.
Conclusions
Our study presents a simple yet robust methodology for the chiral separation of amphetamine enantiomers in wastewater. These results underscore the potential of wastewater-based chiral analysis in monitoring trends in recreational drug use and inform targeted interventions to address substance abuse.
