Enantioselective determination of representative profens in wastewater by a single-step sample treatment and chiral liquid chromatography–tandem mass spectrometry

•Sanple treatment consists in a single, quick and environment-friendly step.•LC–MS/MS is used for the first time for the enantioselective determination of profens.•Method detection limits for enantiomers in sewage are around to or below 1 ng L−1.•Isotopically labelled standards compensate for both recoveries and matrix effects.

This manuscript describes, for the first time, the simultaneous enantioselective determination of ibuprofen, naproxen and ketoprofen in wastewater based on liquid chromatography tandem mass spectrometry (LC–MS/MS). The method uses a single-step sample treatment based on microextraction with a supramolecular solvent made up of hexagonal inverted aggregates of decanoic acid, formed in situ in the wastewater sample through a spontaneous self-assembly process. Microextraction of profens was optimized and the analytical method validated. Isotopically labeled internal standards were used to compensate for both matrix interferences and recoveries. Apparent recoveries for the six enantiomers in influent and effluent wastewater samples were in the interval 97–103%. Low method detection limits (MDLs) were obtained (0.5–1.2 ng L–1) as a result of the high concentration factors achieved in the microextraction process (i.e. actual concentration factors 469–736). No analyte derivatization or evaporation of extracts, as it is required with GC–MS, was necessary. Relative standard deviations for enantiomers in wastewater were always below 8%. The method was applied to the determination of the concentrations and enantiomeric fractions of the targeted analytes in influents and effluents from three wastewater treatment plants. All the values found for profen enantiomers were consistent with those previously reported and confirmed again the suitability of using the enantiomeric fraction of ibuprofen as an indicator of the discharge of untreated or poorly treated wastewaters. Both the analytical and operational features of this method make it applicable to the assessment of the enantiomeric fate of profens in the environment.

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