Multi-residue method for enantioseparation of psychoactive substances and beta blockers by gas chromatography–mass spectrometry

Abstract Currently, consumption of illicit drugs and pharmaceuticals has increased significantly. Many of these substances are chiral and can be available as racemates or enantiomerically pure. Determination of the enantiomeric fraction (EF) in wastewater is useful for: i) distinguishing between the consumption of prescribed and illicit drugs; ii) identification of possible local of illegal synthesis; iii) illegal discharge of sewage and estimation of illicit drugs and pharmaceuticals consumption by a community (wastewater-based epidemiology). This work describes the development of an indirect method by gas chromatography–mass spectrometry (GC–MS) for enantiomeric quantification of chiral substances namely psychoactive drugs and β-blockers based on the formation of diastereomers using (R)-(−)-α-methoxy-α-(trifluoromethyl)phenylacetyl chloride ((R)-MTPA-Cl) as chiral derivatization reagent. The developed method presented linearity (R2 > 0.99) for 20 compounds, 9 diastereomer pairs and paroxetine (PAR) and sertraline (SER). Recovery ranged from 80.7 to 114.5% (RSD