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

The enantioselective composition of ibuprofen in sediments in contact with surface water was evaluated over 168 h 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 0.15 mu g g(-1) for each enantiomer in sediments, and between 2.4 and 3.0 mu g L-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.