Multi-residue enantioselective analysis of chiral drugs in freshwater sediments

Pharmaceutical and illicit drugs are emerging contaminants found in the environment globally. Many are chiral and stereochemistry plays an important role on their environmental fate and effects. However, investigations at the enantiomeric level are limited, particularly for complex particulate matrices such as sediments. This is due to further sample processing requirements and a lack of suitable analytical methods. Therefore, here a new enantioselective methodology is proposed for 15 drugs in sediment. Sample treatment by accelerated solvent extraction and solid phase extraction was critical for subsequent enantioselective separations. Using liquid chromatography–tandem mass spectrometry, a Chiral-V enantioselective column enabled multi-residue separations of anti-depressants, beta-blockers, beta-agonist, anti-histamine and stimulants. Method trueness for all enantiomers was 86–121% and method quantitation limits were below 3 ng g−1 dry weight. Application of the method revealed the enantiomeric composition of fluoxetine, amphetamine, propranolol, venlafaxine and citalopram in sediment for the first time. All drugs except venlafaxine were present in non-racemic form, i.e. unequal enantiomer concentrations. This is significant considering drug toxicity towards benthic organisms could be enantiospecific.