Background: The synthetic drug butylone (2-methylamino-1-(3,4-methylenedioxyphenyl)butan-1-one, BTL) is a chiral cathinone consumed in the form of racemate [1]. After consumption, BTL is metabolized and excreted along with its metabolites, and its residues are carried by sewerage systems to wastewater treatment plants (WWTPs) [2]. Both human metabolism and biodegradation in WWTPs may be enantioselective causing...