Chiral signature of venlafaxine as a marker of biological attenuation processes

The chiral signature of the antidepressant venlafaxine was used in this study to gain insight into biological attenuation processes and to differentiate abiotic and biotic transformation processes in water. Laboratory scale experiments revealed that sorption and phototransformation processes were not enantioselective while venlafaxine was enantioselectively biotransformed into O-desmethylvenlafaxine. The enantiomeric fraction (EF) variations of venlafaxine appeared to be proportional to its microbial fractional conversion. Enantioselective biotransformation of venlafaxine was also investigated in a eutrophic French river. Venlafaxine was found to be racemic at the output of the main wastewater treatment plant discharging into the river, independently of the sampling date during the year. An analysis of EF variations might provide evidence of biodegradation along a 30 km river stretch.

► Chiral separation of venlafaxine and metabolites was achieved in environmental water. ► Biodegradation of venlafaxine was enantioselective in laboratory-scale experiments. ► (R)-venlafaxine was preferentially biotransformed through O-desmethylation. ► Enantiomeric fraction variation was proportional to biodegradation rate. ► Enantioselective biodegradation of venlafaxine was evidenced in a French river.