Dispersive liquid–liquid microextraction and HPLC to analyse fluoxetine and metoprolol enantiomers in wastewaters
Sample extraction is a major step in environmental analyses due both to the high complexity of matrices and to the low concentration of the target analytes. Sample extraction is usually expensive, laborious, time-consuming and requires a high amount of organic solvents. Actually, there is a lack of miniaturized methodologies for sample extraction and chiral analyses. Here, we developed a dispersive liquid–liquid microextraction (DLLME) to extract the pharmaceuticals fluoxetine and metoprolol, as models of basic chiral compounds, from wastewater samples. Compounds were then analysed by enantioselective high-performance liquid chromatography. We monitored the influence of sample pH, extracting and dispersive solvent and respective volumes, salt addition, extracting and vortexing time. The DLLME method was validated within the range of 1–10 µg L−1 for fluoxetine enantiomers and 0.5–10 µg L−1 for metoprolol enantiomers. Accuracy ranged from 90.6 to 106 % and recovery rates from 54.5 to 81.5 %. Relative standard deviation values lower than 7.84 and 9.00 % were obtained for intra- and inter-batch precision, respectively.
KeywordsDispersive liquid–liquid microextraction Sample preparation HPLC-FD Chiral pharmaceuticals Chirobiotic V Wastewaters
The work has been supported by Fundação para a Ciência e Tecnologia—FCT (PhD. grant attributed to ARR and ASM respectively, SFRH/BD/64999/2009 and SFRH/BD/86939/2012), from QREN-POPH, European Social Fund and MCTES. Authors also wish to acknowledge the support from national funds from FCT through projects FLUOROPHARMA, (PTDC/EBB-EBI/111699/2009), PEst-OE/EQB/LA0016/2013 and CEQUIMED-PEst-OE/SAU/UI4040/2014, as well as the support from CESPU through project PHARMADRUGS-CESPU-2014.
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