Antibiotics are the most consumed therapeutic classes worldwide and are released to the environment in their original form as well as potentially active metabolites and/or degradation products. ...Consequences of the occurrence of these compounds in the environment are primarily related to bacterial resistance development.
This work presents a validated analytical method based on solid phase extraction (SPE) using HLB cartridges, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) for quantification of seven different fluoroquinolone antibiotics, namely ciprofloxacin (CPF), enrofloxacin (ENR), lomefloxacin (LOM), norfloxacin (NOR), ofloxacin (OFL), prulifloxacin (PLF) and moxifloxacin (MOX) and its application to detect the target compounds in influents and effluents of wastewater treatment plants (WWTP). Linearity was established through calibration curves in solvent and matrix match using internal calibration method in the range of 50–1300 ng L−1 and all the fluoroquinolones showed good linear fit (r2 ≥ 0.991). Accuracy ranged between 80.3 and 92.9%, precision was comprised between 7.2 and 14.6%, and 10.7 and 18.1% for intra- and inter-batch determinations, respectively. Method detection and quantification limits ranged from 6.7 to 59.0 ng L−1 and 22.3–196.6 ng L−1, respectively.
Influents and effluents of fifteen WWTPs of North of Portugal were analyzed. OFL was the fluoroquinolone found at the highest concentration, up to 4587.0 ng L−1 and 987.9 ng L−1, in influent and effluent, respectively. NOR and PLF were not detected.
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•FQs were analyzed in thirty WWTP samples (influent and effluent) from fifteen WWTPs.•High concentration of ciprofloxacin and ofloxacin was found in WWTP influents.•Ofloxacin was quantified in most of all WWTP effluents.•Important information about FQs in WWTP with different removal systems.
The present works characterizes WWTP influents and effluents regarding seven different fluoroquinolone antibiotics in fifteen Portuguese northern WWTPs with diverse operational features and treatment procedures.
Fluoroquinolones are a class of antibiotics widely prescribed in both human and veterinary medicine of high environmental concern and characterized as environmental micropollutants due to their ...ecotoxicity and persistence and antibacterial resistance potential. Ofloxacin and levofloxacin are chiral fluoroquinolones commercialized as racemate and in enantiomerically pure form, respectively. Since the pharmacological properties and toxicity of the enantiomers may be very different, understanding the stereochemistry of these compounds should be a priority in environmental monitoring. This work presents the biodegradation of racemic ofloxacin and its (S)-enantiomer levofloxacin by the bacterial strains Labrys portucalensis F11 and Rhodococcus sp. FP1 at a laboratory-scale microcosm following the removal and the behavior of the enantiomers. Strain F11 could degrade both antibiotics almost completely when acetate was supplied regularly to the cultures. Enrichment of the (R)-enantiomer was observed in FP1 and F11 cultures supplied with ofloxacin. Racemization was observed in the biodegradation of the pure (S)-ofloxacin (levofloxacin) by strain F11, which was confirmed by liquid chromatography - exact mass spectrometry. Biodegradation of ofloxacin at 450 µg L−1 by both bacterial strains expressed good linear fits (R2 > 0.98) according to the Rayleigh equation. The enantiomeric enrichment factors were comprised between − 22.5% to − 9.1%, and − 18.7% to − 9.0% in the biodegradation of ofloxacin by strains F11 and FP1, respectively, with no significant differences for the two bacteria under the same conditions. This is the first time that enantioselective biodegradation of ofloxacin and levofloxacin by single bacteria is reported.
•Enantioselective degradation of rac-OFL and S-OFL by two bacterial strains was observed.•Degradation of rac-OFL was enantioselective and enhanced in the presence of acetate.•Regular acetate supplementation regime enhanced enantioselective degradation extent.•Rayleigh equation confirmed enantiomeric enrichment during ofloxacin degradation by both strains.•MS analysis confirmed R-OFL formation and identification in S-OFL degradation samples.
•Bio-waste recovery tackles pollution issues related to water, solid waste and air.•Studies using bio-waste to treat real wastewater samples were reviewed.•Bio-sorbents were reported to tackle ...in/organic pollutants (including emerging ones).•Realistic studies on the removal of residues in complex matrices are needed.•Thermally activated bio-waste is proven to efficiently remove metals/organics/dyes.
The conventional waste management practices dispose or incinerate agricultural and forestry waste, contributing to the environmental pollution while misusing biomass, a valuable resource with a great potential of reuse. In fact, cultivation of agricultural crops and harvesting generate an abundant amount of waste (e.g., stones, shells, straw) that can be used for wastewater treatment. Waste biomass may be used as: (i) an adsorbent in its original, raw form, following ambient drying and grinding; (ii) modified bio-based sorbents; or (iii) a source material for the synthesis of activated carbon adsorbents through carbonization. Despite the numerous publications in this field examining the removal of a wide range of target pollutants (metals, metalloids, dyes, pesticides, as well as emerging contaminants) by several materials, more realistic studies are still required to evaluate the potential to remove residual compounds in complex matrices, by testing natural matrices, i.e., environmental samples without spiking the target compounds.
This perspective paper highlights how an integrated-engineering approach may help solving environmental-pollution issues related to water, solid waste, and air pollution. Chiefly, the application of locally produced bio-waste as an adsorbent for wastewater treatment tackles water contamination, decreases the overall amount of agricultural waste, and reduces the potential gas emissions caused by waste transportation, treatment and/or disposal.
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A granular sludge sequencing batch reactor (SBR) was operated for 340 days for treating a synthetic wastewater containing fluoroquinolones (FQs), namely ofloxacin, norfloxacin and ciprofloxacin. The ...SBR was intermittently fed with FQs, at concentrations of 9 and 32 μM. No evidence of FQ biodegradation was observed but the pharmaceutical compounds adsorbed to the aerobic granular sludge, being gradually released into the medium in successive cycles after stopping the FQ feeding.
Overall COD removal was not affected during the shock loadings. Activity of ammonia oxidizing bacteria and nitrite oxidizing bacteria did not seem to be inhibited by the presence of FQs (maximum of 0.03 and 0.01 mM for ammonium and nitrite in the effluent, respectively). However, during the FQs feeding, nitrate accumulation up to 1.7 mM was observed at the effluent suggesting that denitrification was inhibited. The activity of phosphate accumulating organisms was affected, as indicated by the decrease of P removal capacity during the aerobic phase. Exposure to the FQs also promoted disintegration of the granules leading to an increase of the effluent solid content, nevertheless the solid content at the bioreactor effluent returned to normal levels within ca. 1 month after removing the FQs in the feed allowing recovery of the bedvolume. Denaturing gradient gel electrophoresis revealed a dynamic bacterial community with gradual changes due to FQs exposure. Bacterial isolates retrieved from the granules predominantly belonged to α- and γ-branch of the Proteobacteria phylum.
The capacity of the system to return to its initial conditions after withdrawal of the FQ compounds in the inlet stream, reinforced its robustness to deal with wastewaters containing organic pollutants.
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•Effect of ofloxacin, norfloxacin and ciprofloxacin on aerobic granules was studied.•Fluoroquinolones adsorbed reversibly onto granular sludge, no biodegradation occurred.•Prolonged fluoroquinolones feeding led to nitrate accumulation in the SBR effluent.•Exposure to fluoroquinolones destabilized the granules.•Granules quickly recovered after withdrawing fluoroquinolones from influent.
Fluoroquinolone (FQ) antibiotics are extensively used both in human and veterinary medicine, and their accumulation in the environment is causing an increasing concern. In this study, the ...biodegradation of the three most worldwide used FQs, namely ofloxacin, norfloxacin, and ciprofloxacin, by the fluoroorganic-degrading strain Labrys portucalensis F11 was assessed. Degradation occurred when the FQs were supplied individually or as mixture in the culture medium, in the presence of an easily degradable carbon source. Consumption of individual FQs was achieved at different extents depending on its initial concentration, ranging from 0.8 to 30 μM. For the lowest concentration, total uptake of each FQ was observed but stoichiometric fluoride release was not achieved. Intermediate compounds were detected and identified by LC-MS/MS with a quadrupole time of flight detector analyzer. Biotransformation of FQs by L. portucalensis mainly occurred through a cleavage of the piperazine ring and displacement of the fluorine substituent allowing the formation of intermediates with less antibacterial potency. FQ-degrading microorganisms could be useful for application in bioaugmentation processes towards more efficient removal of contaminants in wastewater treatment plants.
•The significance of notations for expressing enantiomeric mixtures and purity.•Notations to express enantiomeric mixtures: their similarities and differences.•Different notations for a single ...measurement: a call for standardization.
The correct quantification of enantiomers is pivotal in a variety of fields, such as pharmacokinetic studies, enantioselective syntheses, chemical characterization of natural products, authentication of fragrance and food, biodegradation behavior, accurate evaluation of environmental risk, and it can also provide information for sentencing guidance in forensic field. Enantioselective chromatography is the first choice to assess the composition of an enantiomeric mixture. Different notations have been used to express the measured enantiomeric ratios, which compromise the results and represent a challenge for data comparison. This manuscript critically discusses the currently used notations and exemplifies with applications in different fields indicating the advantages and disadvantages of one of the adopted systems. In order to simplify the notations, the use of enantiomeric ratio (e.r.%) as standardization for nonchiroptical methods is proposed.
In recent decades, the presence of micropollutants in the environment has been extensively studied due to their high frequency of occurrence, persistence and possible adverse effects to exposed ...organisms. Concerning chiral micropollutants in the environment, enantiomers are frequently ignored and enantiomeric composition often neglected. However, enantioselective toxicity is well recognized, highlighting the need to include enantioselectivity in environmental risk assessment. Additionally, the information about enantiomeric fraction (EF) is crucial since it gives insights about: (i) environmental fate (i.e., occurrence, distribution, removal processes and (bio)degradation); (ii) illicit discharges; (iii) consumption pattern (e.g., illicit drugs, pharmaceuticals used as recreational drugs, illicit use of pesticides); and (iv) enantioselective toxicological effects. Thus, the purpose of this paper is to provide a comprehensive review about the enantioselective occurrence of chiral bioactive compounds in aquatic environmental matrices. These include pharmaceuticals, illicit drugs, pesticides, polychlorinated biphenyls (PCBs) and polycyclic musks (PCMs). Most frequently analytical methods used for separation of enantiomers were liquid chromatography and gas chromatography methodologies using both indirect (enantiomerically pure derivatizing reagents) and direct methods (chiral stationary phases). The occurrence of these chiral micropollutants in the environment is reviewed and future challenges are outlined.
•Evaluation of the enantioselective biodegradation of ofloxacin and levofloxacin by an activated sludge consortium.•Enantiomerization was observed in the biodegradation of the isolated (S)-enantiomer ...with formation of the (R) enantiomer.•Enantioselectivity and enantiomerization during the biodegradation were confirmed by exact mass spectrometry.
Ofloxacin is a chiral fluoroquinolone commercialized as racemate and as its enantiomerically pure form levofloxacin. This work presents an integrated liquid chromatography (LC) method with fluorescence detection (FD) and exact mass spectrometry (EMS) developed to assess the enantiomeric biodegradation of ofloxacin and levofloxacin in laboratory-scale microcosms. The optimized enantioseparation conditions were achieved using a macrocyclic antibiotic ristocetin A-bonded CSP (150×2.1mm i.d.; particle size 5μm) under reversed-phase elution mode. The method was validated using a mineral salts medium as matrix and presented selectivity and linearity over a concentration range from 5μgL−1 (quantification limit) to 350μgL−1 for each enantiomer. The method was successfully applied to evaluate biodegradation of ofloxacin enantiomers at 250μgL−1 by an activated sludge inoculum. Ofloxacin (racemic mixture) and (S)-enantiomer (levofloxacin) were degraded up to 58 and 52%, respectively. An additional degradable carbon source, acetate, enhanced biodegradation up to 23%. (S)-enantiomer presented the highest extent of degradation (66.8%) when ofloxacin was supplied along with acetate. Results indicated slightly higher biodegradation extents for the (S)-enantiomer when supplementation was done with ofloxacin. Degradation occurred faster in the first 3days and proceeded slowly until the end of the assays. The chromatographic results from LC-FD suggested the formation of the (R)-enantiomer during levofloxacin biodegradation which was confirmed by LC–MS with a LTQ Orbitrap XL.
•The multi-techniques analytical approach allowed the evaluation of the degradation of fluoroquinolones by a microbial consortium.•Fluoride ions released exposed the incomplete mineralization of the ...fluoroquinolones.•Metabolites were identified by LC–MS/MS and QqTOF MS.•New structures of the intermediates were proposed.
Antibiotics are a therapeutic class widely found in environmental matrices and extensively studied due to its persistence and implications for multi-resistant bacteria development. This work presents an integrated approach of analytical multi-techniques on assessing biodegradation of fluorinated antibiotics at a laboratory-scale microcosmos to follow removal and formation of intermediate compounds. Degradation of four fluoroquinolone antibiotics, namely Ofloxacin (OFL), Norfloxacin (NOR), Ciprofloxacin (CPF) and Moxifloxacin (MOX), at 10mgL−1 using a mixed bacterial culture, was assessed for 60 days. The assays were followed by a developed and validated analytical method of LC with fluorescence detection (LC–FD) using a Luna Pentafluorophenyl (2) 3μm column. The validated method demonstrated good selectivity, linearity (r2>0.999), intra-day and inter-day precisions (RSD<2.74%) and accuracy. The quantification limits were 5μgL−1 for OFL, NOR and CPF and 20μgL−1 for MOX. The optimized conditions allowed picturing metabolites/transformation products formation and accumulation during the process, stating an incomplete mineralization, also shown by fluoride release. OFL and MOX presented the highest (98.3%) and the lowest (80.5%) extent of degradation after 19 days of assay, respectively. A representative number of samples was selected and analyzed by LC–MS/MS with triple quadrupole and the molecular formulas were confirmed by a quadruple time of flight analyzer (QqTOF). Most of the intermediates were already described as biodegradation and/or photodegradation products in different conditions; however unknown metabolites were also identified. The microbial consortium, even when exposed to high levels of FQ, presented high percentages of degradation, never reported before for these compounds.
The importance of stereochemistry for medicinal chemistry and pharmacology is well recognized and the dissimilar behavior of enantiomers is fully documented. Regarding the environment, the ...significance is equivalent since enantiomers of chiral organic pollutants can also differ in biodegradation processes and fate, as well as in ecotoxicity. This review comprises designed biodegradation studies of several chiral drugs and pesticides followed by enantioselective analytical methodologies to accurately measure the enantiomeric fraction (EF). The enantioselective monitoring of microcosms and laboratory-scale experiments with different environmental matrices is herein reported. Thus, this review focuses on the importance of evaluating the EF variation during biodegradation studies of chiral pharmaceuticals, drugs of abuse, and agrochemicals and has implications for the understanding of the environmental fate of chiral pollutants.
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