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- Dispersive liquid–liquid microextraction and HPLC to analyse fluoxetine and metoprolol enantiomers in wastewatersPublication . Ribeiro, Ana R.; Gonçalves, Virgínia M. F.; Maia, Alexandra S.; Ribeiro, Cláudia; Castro, Paula M. L.; Tiritan, Maria E.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 A mu g L-1 for fluoxetine enantiomers and 0.5-10 A mu g 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.
- Microbial degradation of pharmaceuticals followed by a simple HPLC-DAD methodPublication . Ribeiro, Ana R.; Goncalves, Virgínia M.F.; Maia, Alexandra S.; Carvalho, Maria F.; Castro, Paula M.L.; Tiritan, Maria E.The biodegradation of five pharmaceutical ingredients (PIs) of different therapeutic classes, namely antibiotics (trimethoprim, sulfametoxazole and ciprofloxacin), anti-inflammatory (diclofenac) and anti-epileptic (carbamazepine), by two distinct microbial consortia, was investigated. For the monitoring of biodegradation assays, a simple HPLC-DAD (High Performance Liquid Chromatography – Diode Array Detector) method was developed and validated. The separation of the target pharmaceuticals was performed using an environmental friendly mobile phase in a gradient mode of 0.1% triethylamine (TEA) in water acidified at pH 2.23 with trifluoroacetic acid (TFAA) and ethanol as organic solvent. The method revealed to be selective, linear and precise in the range of 1.0 to 30.0 μg/mL for all PIs. Biodegradation assays were performed using activated sludge and a bacterial consortium (able to degrade fluoroaromatic compounds) supplemented with the target PIs at a final concentration of 25 μg/mL. The results revealed that activated sludge removed the target compounds more efficiently than the bacterial consortium.