Enantioselective determination of ibuprofen residues by chiral liquid chromatography: a systematic study of enantiomeric transformation in surface water and sediments

Environmental context Ibuprofen, a common anti-inflammatory drug and one of many pharmaceuticals sold as a mixture of enantiomers, has recently been found in river and surface waters. There are, however, few analytical methods able to separate and accurately measure ibuprofen enantiomers in environmental matrices. This study reports a method for quantifying ibuprofen enantiomers in sediments and surface water, and applies it to shed light on the degradation and fate of the enantiomers in aquatic systems. Abstract The enantioselective composition of ibuprofen in sediments in contact with surface water was evaluated over 168h in the presence and absence of light. Multivariate techniques applied for the evaluation of enantiomeric fraction (EF) and recoveries of enantiomers in water and sediments show differences in the EF and composition of each enantiomer. In sediments, differences in the EF are a result of the presence or absence of light, whereas in water it is attributable to degradation of the two enantiomers with time. To achieve enantioselective separation of ibuprofen in surface water and sediments, a clean-up and preconcentration procedure using solid phase extraction combined with a direct chiral liquid chromatography–ultraviolet method was developed. Quantitation limits of the proposed method were between 0.12 and 0.15µgg–1 for each enantiomer in sediments, and between 2.4 and 3.0µgL–1 in surface water. Intra- and inter-day precisions were between 5.1 and 8.9%. Multivariate techniques can be useful to identify enantiomeric modifications and to select the variables that should be used for modelling such transformations.