Loading...
54 results
Search Results
Now showing 1 - 10 of 54
- Biodegradation of chiral pharmaceuticals by an activated sludge consortium followed by a Chiral HPLC-FDPublication . Ribeiro, Ana R.; Castro, P. M. L.; Afonso, Carlos; Tiritan, MariaBiodegradation tends to be enantioselective in contrast to abiotic degradation and it is necessary enantioselective analytical methods to quantify the enantiomeric fraction of chiral pharmaceuticals in the environment for correct risk assessment. In this work, we developed HPLC-FD methods to follow the biodegradation of four beta-blockers: alprenolol , propranolol , metoprolol and atenolol and the antidepressant fluoxetine during 15 days in batch mode. The biodegradation assays were performed using AS from the aerated tanks of a municipal wastewater treatment plant with a singly compound supplementation and a mixture compound supplementation similar to those found in wastewater influents. Abiotic degradation in the presence of light and in the dark was evaluated. Either the low concentration or the mixture effects are situations closer to those found in the environment. The results indicate the higher degradation extents for the S-enantiomer forms, as is shown in Figure 1.
- Studies on enantioselective biodegradation of fluoxetinePublication . Moreira, Irina S.; Ribeiro, Ana R.; Amorim, Catarina L.; Tiritan, Maria E.; Castro, Paula M. L.Fluoxetine (FLX) is a chiral fluorinated pharmaceutical indicated mainly for treatment of depression and is one of the most dispensed drugs in the world. There is a clear evidence of environmental contamination with this drug. Granular sludge sequencing batch reactors (SBR) constitute a promising technology for the treatment of effluents containing micropollutants. In this study, a SBR was operated in order to assess its performance when treating a synthetic wastewater containing racemic FLX (rac-FLX), under continuous and intermittent feeding of the compound. The concentration of FLX enantiomers was followed using an enantioselective HPLC method. A removal of 70% of the total supplied FLX was observed in the first continuous feeding period. However, the subsequent feeding periods revealed a significant decrease in the FLX removal; FLX liberation occurred during periods when no compound was supplied. This can be probably explained by desorption of FLX previously adsorbed to the granules. No intermediate metabolites or fluoride release were detected, corroborating the hypothesis that adsorption of FLX to the aerobic granules occurred. Moreover, the absence of enantioselectivity in the decrease of FLX enantiomers concentration is also an indicator of an abiotic mechanism. In face of the incapacity of the aerobic granules to biodegrade FLX, the ability of Labrys portucalensis F11, a previously isolated microbial strain with the capacity to degrade a range of fluorinated aromatic compounds, to biodegrade this compound was investigated. In this study, the enantioselective biodegradation of rac-FLX and of its enantiomers was assessed. The results obtained revealed that this strain is able to degrade both enantiomers of FLX, when supplemented as a racemic mixture, as well as when supplemented as a single enantiomers. Preferential degradation of the (R)-enantiomer was observed. This feature makes L. portucalensis F11 a potential candidate for devising biodegradation technologies able to deal with contamination by this pharmaceutical. Acknowledgements: I.S. Moreira, A.R. Ribeiro and C.L. Amorim wish to acknowledge a research grant from Fundação para a Ciência e Tecnologia (FCT), Portugal (Ref. SFRH/BPD/87251/2012, SFRH/BD/64999/2009 and SFRH/BD/47109/2008 , respectively) and Fundo Social Europeu (Programa Operacional Potencial Humano (POPH), Quadro de Referência Estratégico Nacional (QREN)). This work was supported by FCT through the projects PTDC/EBB-EBI/111699/2009, CEQUIMED-Pest-OE/SAU/UI4040/2011 and PEst-OE/EQB/LA0016/2011.
- Removal of a mixture of chiral pharmaceuticals by an aerobic granular sludge bioreactor and its effects on the biomassPublication . Amorim, Catarina L.; Moreira, Irina S.; Ribeiro, Ana R.; Santos, Lúcia; Delerue-Matos, Cristina; Tiritan, Maria E.; Castro, Paula M. L.
- Microbial degradation of 17β -estradiol and 17α -ethinylestradiol followed by a validated HPLC-DAD methodPublication . Ribeiro, Ana R.; Carvalho, Maria F.; Afonso, Carlos M. M.; Tiritan, Maria E.; Castro, Paula M.L.This work aimed at studying the biodegradation of two estrogens, 17agr -estradiol (E2) and 17β -ethinylestradiol (EE2), and their potential metabolism to estrone (E1) by microbial consortia. The biodegradation studies were followed by High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) using a specifically developed and validated method. Biodegradation studies of the estrogens (E2 and EE2) were carried out with activated sludge (consortium A, CA) obtained from a Wastewater Treatment Plant (WWTP) and with a microbial consortium able to degrade recalcitrant compounds, namely fluorobenzene (consortium B, CB). E2 was more extensively degraded than EE2 by CA whereas CB was only able to degrade E2. The addition of acetate as a supplementary carbon source led to a faster biodegradation of E2 and EE2. E1 was detected as a metabolite only during the degradation of E2. The 16S rRNA gene sequence analyses of strains recovered from the degrading cultures revealed the presence of the genera Pseudomonas, Chryseobacterium and Alcaligenes. The genera Pseudomonas and Chryseobacterium were retrieved from cultures supplied with E2 and EE2, while the genus Alcaligenes was found in the presence of E2, suggesting that they might be involved in the degradation of these compounds.
- Development and Optimization of an Online SPE-HPLC-FD Method for Quantification of Fluoroquinolones in Wastewater EffluentsPublication . Meira, Bernardo; Maia, Alexandra S.; Gonçalves, Virgínia M. F.; Ribeiro, Ana R.; Tiritan, Maria E.Fluoroquinolones are antimicrobial agents widely found in environmental matrices and extensively studied due to their persistence and implications for multiresistant bacteria. The presence of fluoroquinolones in the environment is mainly due to the incapability of wastewater treatment plants (WWTPs) to completely remove those compounds. The amount of fluoroquinolones released through effluents depends on the type of treatment used by the WWTPs. So, accurate analytical methods to quantify those compounds on WWTPs process and in effluents are crucial. Solid phase extraction (SPE) coupled to liquid chromatography is a straightforward technique that provides analyte extraction, cleanup, separation and detection while providing a good reproducibility and efficiency. The purpose of this work was the establishment of a novel method for quantification of Ofloxacin, Norfloxacin, Ciprofloxacin and Moxifloxacin on WWTPs effluents using on-line SPE. Samples were injected directly on a restricted access material column LichroCart 25-4 Lichrospher® RP-18 ADS (25 μm) and then transferred to an analytical column Luna PFP (2) (150 x 4.6 mm ID, 100 Å, 3 μm) for separation in isocratic mode with a mixture of 0.1% triethylamine in water (acidified to pH = 2.2 with trifluoroacetic acid) and ethanol as mobile phase; column oven was set at 45ºC. The detection was performed by fluorescence with an excitation wavelength of 290 nm and an emission wavelength of 460 nm. The injection volume of 100 μL of previous preconcentrated sample was compared with larger volume injection of only filtered effluent samples. The study was conducted with effluent samples collected from a municipal WWTP in the north of Portugal.
- HPLC-FD method to follow biodegradation of four fluoroquinolonesPublication . Maia, Alexandra; Duque, Anouk F.; Ribeiro, Ana L.; Castro, Paula M. L.; Tiritan, Maria E.
- Biodegradation of fluoroquinolones by single bacteriaPublication . Amorim, Catarina L.; Moreira, Irina S.; Maia, Alexandra; Tiritan, Maria E.; Castro, Paula M. L.
- Remoção de fluoroquinolonas do ambiente: biossorção a lamas ativadas e a grânulos aeróbiosPublication . Ferreira, Vanessa R. A.; Amorim, Catarina L.; Cravo, Sara M.; Tiritan, Maria E.; Castro, Paula M. L.; Afonso, Carlos M. M.Diversas matrizes ambientais, particularmente águas residuais, têm revelado a presença de antibióticos. Embora presentes em níveis vestigiais (ng.L-1 a µg.L-1,), estes compostos são pseudo-persistentes e, naquelas concentrações, podem também promover resistências nas populações bacterianas [1]. Estudos recentes de remoção de antibióticos com lamas ativadas (AS) e grânulos aeróbios (AGS) mostram a biossorção como processo dominante e eficaz na remoção destes micropoluentes [2,3]. O presente trabalho explorou a biossorção de três fluoroquinolonas (FQ) - ofloxacina (OFL), norfloxacina (NOR) e ciprofloxacina (CPF) - a AS e AGS. Com vista a uma melhor compreensão dos fenómenos que ocorrem durante o processo, foram estudados diversos parâmetros que condicionam a biossorção. As AS demonstraram melhor desempenho na remoção da OFL, NOR e CPF relativamente aos AGS. No entanto, nas concentrações estudadas, não foi possível promover a remoção total dos fármacos. A capacidade mais elevada de biossorção das AS foi atribuída à carga negativa da superfície da biossorção, representada por um potencial zeta de -25,65 mV, a pH 7. A OFL foi a FQ menos removida, tanto pelas AS como pelos AGS, porque a OFL a pH 7 está principalmente presente na forma aniónica, com uma pequena percentagem, na forma zwiteriónica. Em AGS verifica-se um aumento da biossorção da OFL, NOR e CPF em pH ácido (pH 4) e maior dessorção em pH alcalino (pH 8 a 9). Observou-se também que ocorre a destruição da estrutura granular dos AGS quando o pH do meio é igual ou inferior a 3. Os resultados obtidos neste estudo contribuem para uma utilização mais eficaz de AS e AGS na remoção de antibióticos fluoroquinolonas do ambiente.
- Fármacos quirais em diferentes matrizes ambientais: ocorrência, remoção e toxicidadePublication . Ribeiro, Ana R.; Afonso, Carlos; Castro, Paula M. L.; Tiritan, Maria E.In recent decades, the occurrence of pharmaceuticals in the environment has been widely reported due to their high frequency and recalcitrance in many cases. Concerning the chiral pharmaceuticals (CPs) in environmental matrices, the stereochemistry is often neglected and enantiomers are determined together as unique molecules. However, it is well known that CPs might have enantioselective toxicity, rendering important to assess the occurrence and degradation processes of single enantiomers in the environment, namely during biological treatment in wastewater treatment plants (WWTPs). The development of analytical methods to qualitatively and quantitatively evaluate the enantiomers of CPs is crucial for determining enantiomeric fraction (EF). The EF is the most important parameter in studies involving enantiomers and enantioselective processes and fundamental in biodegradation studies and wastewater monitoring. This review summarizes the analytical methods used to determine EF of CPs in environmental matrices and/or during biodegradation processes. The occurrence of CPs in the environment and their biodegradation are reviewed and future trends in the area outlined.
- Enantioselective Degradation of Enantiomers of Fluoxetine Followed by HPLC- FDPublication . Ribeiro, Ana R.; Maia, Alexandra S.; Moreira, Irina S.; Afonso, Carlos; Castro, Paula M.L.; Tiritan, Maria E.Environmental fate assessment of chiral pharmaceuticals is an important issue and little information is known about enantioselectivity in the environment. This kind of information is important for regulamentation of pharmaceutical industry and chiral switching processes. Fluoxetine (FLX), an anti-depressant worldwide used, is a chiral pharmaceutical prescribed in racemic form, and its main metabolite norfluoxetine (NFLX) is also chiral. In this study, enantioselective degradation of rac-FLX and degradation of its enantiomers separately, in a minimal salts medium inoculated by a bacterium consortium was examined both at light and dark conditions. Theassays were performed in a shaker at aerobic and ambient temperature conditions. The analytical method used was an enantioselective HPLC-FD method using a vancomycin-based chiral stationary phase in reversed mode to monitor enantiomers of FLX and NFLX. No degradation of enantiomers of FLX in the abiotic controls was observed. In theall assays (R)-FLX was degraded faster and totally until day 24th while (S)-FLX remained up to 20% of its initial concentration until the end of the experiment (38 days). NFLX wasdetected in all biotic experiments.