Federica Maraschi

University of Pavia, Ticinum, Lombardy, Italy

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Publications (29)88.68 Total impact

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    ABSTRACT: The aim of this paper was to evaluate silicon (Si) concentration in human whole ventricular blood as a further potential chemical marker in the diagnosis of drowning. We employed an acidic digestion for the extraction of soluble Si, and an alkaline digestion for the determination of total Si, including particulate matter, both arising from drowning medium. 29 suspected drowning situations, 24 in fresh water (Fw) and 5 in seawater (Sw), were examined. The difference in Si concentration between the left and right ventricular blood (Si ΔL-R) was measured and alkaline Si ΔL-R seems, indeed, a potentially significant complementary tool in the diagnosis of Fw drowning, because insoluble silicon fraction does not undergo hemo-dilution or hemo-concentration, and the ΔL-R is not affected by exogenous factors. In spite of the limited number of cases investigated, a good correlation was observed between the analytical results and the macro-microscopic autoptic findings.
    No preview · Article · Jan 2016 · Journal of Forensic and Legal Medicine
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    ABSTRACT: Sepiolite is studied as sorbent for removal of Fluoroquinolone (FQ) contaminants from water. Marbofloxacin (MAR) and Enrofloxacin (ENR) were chosen as model FQs since they are the two most commonly employed veterinary FQs in livestock farming in northern Italy. Adsorption experiments on two sepiolites (SP-1 and SSE16) were carried out in tap water at pH 7.5 to better mimic real conditions. The sorption experimental data were fitted by Freundlich, Langmuir and S-Logistic1 models. The latter better described MAR and ENR adsorptions. Adsorption capacities of SP-1 and SSE16, respectively, were 132 mg g−1 and 121 mg g−1 for MAR, and 112 mg g−1 and 93 mg g−1 for ENR. X-ray powder diffraction, performed on clay samples enriched with each FQ and on the pristine clays, showed no substantial differences between the two sepiolites and evidenced no significant structural changes after FQs uptake, as also verified by infrared spectroscopy. This indicates that adsorption occurs only on the external surface of the mineral and not in the intracrystalline microporosity, likely due to the interaction between the FQ carboxylic group and the sepiolite surface. For the first time solid-state photodegradation of the adsorbed FQs was investigated for regenerating the sorbent. Results showed that the adsorbed drugs are effectively photodegraded by solar light, thus allowing sepiolite to be reused. The efficiency of this material for remediation of contaminated water was proved on ditch water, collected downstream a swine farm, containing some tens of ng L−1 of MAR and ENR.
    Full-text · Article · Dec 2015 · Chemosphere
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    ABSTRACT: Benzotriazoles (BTRs), benzothiazoles (BTs) and benzenesulfonamides (BSAs), compounds largely used in industrial and household applications, are ubiquitous emerging contaminants. In this work a novel, straightforward procedure for the simultaneous determination of two BTRs (1H-benzotriazole, 5-methyl-1H-benzotriazole), three BTs (benzothiazole, 2-hydroxybenzothiazole, 2-methylthiobenzothiazole) and two BSAs (benzenesulfonamide, toluenesulfonamide) in soil has been developed. The target analytes were extracted from soil by a single low-pressurized microwave-assisted extraction (MAE) cycle (120 °C, 10 min) and quantified by high-performance liquid chromatography with UV detection. For all the seven analytes, quantitative extraction yields (72-119%, n=4) were observed from recovery tests on soil samples (1 g) spiked with 5, 10 and 50 mg kg-1, using 4 mL water-methanol (85:15) as extracting solution. For the lower concentrations levels (100, 250 and 500 μg kg-1), the analytes were extracted from soil samples (2-3 g) using 6 mL methanol, and the extract was pre-concentrated by evaporation before analysis; recoveries in the range 70-117% were obtained (n=4). Suitable intra-day and inter-day precision were observed, with values of relative standard deviation generally below 6% and 11% (n=4), respectively. Linearity was evaluated in the concentration range 0.5-10 mg L-1 by matrix-matched standards, obtaining r2>0.9996. The experimental method quantification limit (MQL) was 100 μg kg-1. The entire procedure has been successfully applied to the analysis of real impacted soil samples.
    Full-text · Article · Sep 2015 · Talanta
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    ABSTRACT: A novel, simple and straightforward method for determination of fluoroquinolones (FQs) in compost has been developed. The procedure entails a low-pressurized microwave-assisted extraction (MAE) carried out by a high performance instrument, in alkaline aqueous solution containing magnesium ions as FQs complexing agent, followed by ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS). Ciprofloxacin (CIP), Enrofloxacin (ENR), Levofloxacin (LEV) and Norfloxacin (NOR), four widely used FQ antibiotics, were simultaneously extracted from compost by a single MAE cycle (20min, 135°C). The method was validated in terms of linearity, selectivity, sensitivity and accuracy. Quantitative absolute recovery (70-112%, n=3) and suitable precision (RSD<15%, n=3) were observed, at concentration levels ranging from 25 ng g(-1) to 2500 ng g(-1). Analytes were separated in a 10min chromatographic run and quantified/confirmed in single reaction monitoring (SRM) mode. UPLC coupled to SRM-MS detection allowed to achieve improved sensitivity, and selective detection. Method detection and quantification limits, MDLs and MQLs, were in the range 2.2-3.0 ng g(-1) and 6.6-9.0 ng g(-1), respectively. The high-performance microwave system here used strongly improved the extraction efficiency with respect to a conventional apparatus. The procedure proved to be simpler, less expensive, faster, and more green with respect to the few methods currently described in literature, providing at the same time suitable recovery and reproducibility. The analytical method has been applied to the analysis of actual compost samples, wherein FQs have been quantified at concentrations up to 88 ng g(-1). Copyright © 2015 Elsevier B.V. All rights reserved.
    Full-text · Article · Jul 2015 · Journal of Chromatography A
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    ABSTRACT: The photodegradation of Ciprofloxacin (CIP), Enrofloxacin (ENR), Danofloxacin (DAN), Marbofloxacin (MAR) and Levofloxacin (LEV), five widely used fluoroquinolones (FQs), was studied in urban WWTP secondary effluent, under solar light. The degradation profiles and the kinetic constants were determined at the micrograms per litre levels (20-50μgL(-1)). The photo-generated products were identified by high-pressure liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The toxicity of the photoproducts was assessed by Vibrio fischeri light emission inhibition assay performed on irradiated and not-irradiated FQs solutions, at environmentally significant concentrations. Attention was focused on the evaluation of the photoproducts contribution to the overall biotoxic effect of these emerging pollutants. Data from chronic exposure experiments (24-48h) were primarily considered. Results confirmed the major usefulness of chronic toxicity data with respect to the acute assay ones and proved the not negligible biotoxicity of the FQs photodegradation products. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Full-text · Article · Apr 2015 · Chemosphere
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    ABSTRACT: This work presents the results obtained in using olive mill wastewater (OMW) as sacrificial agent for the photocatalytic H2 evolution from water, at ambient temperature and pressure. The effects of irradiation time, catalyst amount, pH, and OMW concentration have been investigated. Under the best experimental conditions (4 h UV-A irradiation, 2 g L−1 Pt/TiO2, OMW 3.3% v/v, COD 944 mg L−1, pH 3) up to 44 μmol H2 were generated from aqueous samples. Consecutive irradiation cycles (4 × 4 h) on the same sample provided ca. 280 μmol H2, corresponding to 82% of the yield observed, under the same conditions and COD value, by using glucose as test sacrificial agent. H2 evolution was strongly improved (+81%) by pre-treating OMW with magnesium silicate (125 g L−1, 6 h contact), achieving a production of ca. 80 μmol H2 by 4 h UV-A irradiation. The possibility to exploit sunlight in the photocatalytic process was gained by using Eosin Y/Pt/TiO2. Under solar light the H2 yield resulted to be 66% with respect to that obtained by UV-A radiation. Beside some general mechanistic aspects of the photocatalytic process, benefits and drawbacks in recycling OMW for photocatalytic H2 evolution from water have been highlighted.
    Full-text · Article · Mar 2015 · International Journal of Hydrogen Energy
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    ABSTRACT: Fluoroquinolone antibiotics (FQs) are important “emerging” micropollutants, and their environmental diffusion is an issue of great concern. In this study, the photochemical degradation of marbofloxacin (MAR) and enrofloxacin (ENR) adsorbed on montmorillonite (MMT) and kaolinite (KAO) clays was investigated. Being FQs photosensitive molecules, the sunlight-induced degradation of clay-adsorbed FQs and of their photoproducts was monitored as function of irradiation time. The photoproducts were identified by high performance liquid chromatography electrospray tandem mass spectrometry (HPLC-ESI-MS/MS) and the photochemical pathways have been elucidated. X-ray diffraction (XRD) has been employed to deeply study the solid-state photodegradation process of MAR and ENR on MMT. Interestingly, the XRD results clearly evidenced a significative variation of the interlayer spacing of MMT not only as function of FQs adsorbed amounts, but also in relationship with their photodegradation, not investigated by means of XRD as yet. The results confirmed that FQs adsorption is a bulk phenomenon that occurs in the interlayer spacing of the MMT structure; moreover, it was proved that sunlight largely degraded the adsorbed FQs, both on the external surface and in the interlayer spacing.
    Full-text · Article · Feb 2015 · Journal of Photochemistry and Photobiology A Chemistry
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    ABSTRACT: This work presents a novel analytical method based on graphene for the determination of five widely used fluoroquinolones (FQs) in aqueous matrices. The procedure entails solid-phase extraction (SPE) on graphene-derivatized silica (200mg), followed by liquid chromatography with fluorescence detection. Monolayer graphene oxide (GO) flakes were covalently bonded onto aminopropyl silica microparticles, and then treated with aqueous hydrazine to obtain the reduced GO (RGO). The final material (RGO-silica) was characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and BET analysis, and for the first time evaluated as mixed-mode sorbent for the SPE of FQs from natural waters. Accuracy was studied on tap/raw river water in the concentration range 5-10,000ngL(-1), obtaining mean absolute recoveries from 72 to 118%. The inter-day precision was good, showing relative standard deviations (RSDs) in the range 5-15%. Sample volumes up to 1L provided enrichment factors up to 1000, achieving accurate quantification of concentrations as low as 5ngL(-1). The analytes were simultaneously and quantitatively eluted from the RGO-silica cartridge in a single fraction by using acetonitrile combined with aqueous tetrabutyl ammonium hydroxide. The batch-to-batch reproducibility was verified on three independently prepared RGO-silica samples. RGO-silica was advantageous in terms of adsorption capacity and reusability with respect to commercial sorbents; the cartridge proved to be reusable for at least 10 consecutive extractions, with no significant loss of efficiency (recovery >70%). The analytical procedure was applied to the determination of FQs in actual environmental waters. Copyright © 2014 Elsevier B.V. All rights reserved.
    Full-text · Article · Jan 2015 · Journal of Chromatography A
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    ABSTRACT: Nanosized titanium dioxide immobilized on silica gel was synthesized and used as fixed-bed phase for V(V) pre-concentration, followed by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. Three different sorbents were prepared by sol-gel method starting from a mixture of titanium isopropoxide, 2-propanol and water, and characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and BET analysis. V(V), the most stable and toxic oxidation state of the element, present in water and beverages samples, was selectively sorbed, pre-concentrated, quantitatively eluted by 0.1 M HCl and analyzed by ICP-OES. The effectiveness of the procedure was first assessed on tap water enriched with 1 μg L-1 of V(V) obtaining recoveries up to 92% (n=4). The pre-concentration step was then optimized for complex matrices such as tea infusions and red and white wines. The reliability of the procedure was assessed on the same beverages samples spiked with 20-250 μg L-1. Quantitative recoveries (82-95%, n=4) were assured avoiding any sample pre-treatment, generally essential in such complex matrices, obtaining good precision (RSD<12%, n=3). The method was then applied to the determination of V(V) in commercial tea infusions and wines.
    Full-text · Article · Jan 2015 · Arabian Journal of Chemistry
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    ABSTRACT: Adsorption and photocatalytic removal from water of marbofloxacin (MAR) and enrofloxacin (ENR), two fluoroquinolone (FQ) antibiotics widely present in surface waters, were investigated on zeolite Y derivatized with three different TiO2 catalysts (P25 Degussa and TiO2 obtained by optimization of a sol–gel method). The prepared materials were characterized by X-rays powder diffraction (XRPD), scanning electron microscopy (SEM), BET analysis and diffuse reflectance spectroscopy (DRS). TiO2-derivatization improved the adsorption capacities of zeolite Y for FQs and promoted the sunlight-induced degradation of FQs adsorbed (solid-state photodegradation), not investigated in literature yet. A large FQs removal (3 mg g−1) occurred in about 2 h (residual adsorbed FQs < 0.03%). The degradation curves of FQs and the evolution profiles of the photoproducts were monitored, after microwave-assisted extraction, by high-performance liquid chromatography coupled to UV detection (HPLC-UV), thus proving the effectiveness of solar radiation in the photocatalytic removal of the drugs adsorbed on TiO2-modified zeolites, that can be recycled for further adsorption/photodegradation cycles, with no loss of sorption capability and photocatalytic activity. A complete removal of FQs from the outlet of a wastewater treatment plant samples, spiked with MAR and ENR at the micrograms per litre levels, was obtained with the best performing modified zeolite.
    Full-text · Article · Aug 2014 · Journal of Environmental Chemical Engineering
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    ABSTRACT: This work presents a systematic study of cellulose (CLS) as a sacrificial biomass for photocatalytic H2 evolution from water. The idea is indeed to couple a largely available and not expensive biomass, and water, with a renewable energy like solar radiation. An aqueous CLS suspension irradiated either at 366 nm (UV-A) or under sunlight in the presence of Pt/TiO2 behaves as a H2 evolving system. The effects of irradiation time, catalyst and CLS concentrations, pH and water salinity are studied. Addition of CLS to the sample significantly improved H2 evolution from water splitting, with yields up to ten fold higher than those observed in neat water. The mechanism of the photocatalytic process relies on the TiO2-mediated CLS hydrolysis, under irradiation. The polysaccharide depolymerisation generates water-soluble species and intermediates, among them 5-hydroxymethylfurfural (HMF) was identified. These intermediates are readily oxidized following the glucose photoreforming, thus enhancing water hydrogen ion reduction to give gas-phase H2. The formation of "colored" by-products from HMF self-polymerization involves a sort of "in situ dye sensitization" that allows an effective photoreaction even under solar light. The procedure is evaluated and successfully extended on cellulosic biomasses, i.e. rice husk and alfalfa (Medicago sativa) stems, not previously investigated for this application.
    Full-text · Article · Jun 2014 · Photochemical and Photobiological Sciences
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    ABSTRACT: This is the first-time reporting on the photocatalytic production of hydrogen gas (H-2) via water splitting in the presence of swine sewage (SS) as sacrificial agent. H-2 was evolved upon both UV-A and solar light irradiation in presence of platinised titania as the catalyst. The influences of irradiation time, catalyst amount, pH and SS concentration on the reaction yield were investigated. Under the best conditions, up to 50 mu mol of H-2 were produced from aqueous SS (1.7% v/v, COD 82 mg L-1), with good within-laboratory reproducibility (RSD <3%, n = 3). The batch-to-batch reproducibility was verified, too. Despite the complexity of the matrix, the amount of evolved H-2 was about a half of that obtained by use of model sacrificial agents as glucose, sucrose and glycerol, known to be excellent electrondonors. The catalyst, recovered after irradiation, was regenerated by mere washing with acidic water and conserved part of the activity for reusing for at least 3 runs. The proposed procedure is at low environmental impact, does not release carbon dioxide and proceeds also under solar light with reaction yields up to 94% compared to those observed under UV-A radiation. This explorative study demonstrates that a waste such as SS is a rewarding and inexpensive feedstock to produce a high-value chemical as hydrogen gas. The results suggest that further work should be addresses in this direction. Copyright
    Full-text · Article · May 2014 · International Journal of Hydrogen Energy
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    ABSTRACT: The adsorption of two veterinary fluoroquinolones, Enrofloxacin (ENR) and, for the first time, Marbofloxacin (MAR), was investigated on kaolinite and montmorillonite clays with the aim of evaluating the efficiency of these adsorbents in removing pharmaceuticals from soils and waters. Experiments were carried out at two different pHs in tap water and aqueous salt solution. Adsorption isotherms show that these drugs were adsorbed in remarkable amounts by the three materials examined (STx-1, SWy-1, kaolinite) with different mechanisms, as confirmed by XRD (X-ray diffraction) analysis. Different thermodynamic models have been applied and the best fit was obtained by means of Langmuir interactions models. In order to remove FQs from contaminated wastewaters, the three clays were contacted with water samples collected from ditches near cattle and swine farms obtaining a quantitative removal. The results proved that such minerals are suitable for the remediation of environmental matrices.
    Full-text · Article · Nov 2013 · Journal of Environmental Chemical Engineering
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    ABSTRACT: The photodegradation fate of widely used fluoroquinolone (FQ) drugs has been studied both at the water-soil interface and in soil at actual concentrations (500 ng g(-1)) under natural solar light. Both human and veterinary drugs have been examined, namely ciprofloxacin, danofloxacin, enrofloxacin, levofloxacin, marbofloxacin and moxifloxacin. After spiking and irradiation, samples were submitted to microwave-assisted extraction and analyzed by high-performance liquid chromatography coupled to fluorescence detection (HPLC-FD). FQs degradation was faster in aqueous soil suspension than in neat soil (but lower than in "clean" water). A number of byproducts were identified by HPLC electrospray ionization tandem mass spectrometry after a post-extraction cleanup based on a molecularly imprinted polymer phase, for a more accurate detection. The distribution in the suspension was intermediate between those observed in soils and in aqueous solutions.
    Full-text · Article · Sep 2013 · Environmental Science and Pollution Research
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    ABSTRACT: MAR and ENR adsorption and photodegradation were investigated on NaY zeolite derivatized with three different TiO2 catalysts (ZT1= NaY-P25 Degussa, ZT2= NaY amorphous TiO2, ZT3= NaY-anatase TiO2) after acidic washing. The obtained materials were characterized by XRD, SEM, diffuse reflectance analysis and BET. The adsorption isotherms, investigated in natural water at native pH, showed that FQs are adsorbed in remarkable amounts by ZT2 and ZT3, with sorption capacities significantly higher than those observed for ZT1 and untreated zeolite. Photodegradation kinetics of adsorbed FQs were investigated on each material and demonstrated that solid-state photoreaction of these antibiotics takes place effectively. The degradation rate was greatly enhanced on the TiO2-modified zeolites, with a large FQs removal in about 2 hours for a 3-6 mg g-1 load. A comparable degradation required about 15 hours on untreated zeolite. Modifications in the course of the photoreaction in the adsorbed state were investigated by examining the product distribution under these conditions with respect to solution. Microwave-assisted extraction in aqueous Mg2+ [5] followed by HPLC-UV analysis was employed. The photoproducts were identified by HPLC-ESI/MS. The application of the above titanate zeolites under actual environment conditions was then tested on water samples collected at the outlet of a wastewater treatment plant. Under these conditions, complete removal of FQs present at the microgram per litre levels was achieved.
    Full-text · Conference Paper · Jun 2013
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    ABSTRACT: The photodegradation fate of widely used Fluoroquinolones (FQs) in solid environmental matrices has been studied at actual concentrations (500 ng g-1) under natural solar light. Both human and veterinary drugs have been chosen, namely Ciprofloxacin (CIP), Danofloxacin (DAN), Enrofloxacin (ENR), Levofloxacin (LEV), Marbofloxacin (MAR) and Moxifloxacin (MOX). In this work, the photochemical behaviour of adsorbed FQs at the water-soil interface was investigated for the first time, in view of the great relevance to natural ecosystems and compared to their photodegradation in sunlit soil. After spiking and irradiation, samples were submitted to microwave-assisted extraction and analyzed by high performance liquid chromatography coupled to fluorescence detection (HPLC-FD). The photochemical fate of the parent compound and the time evolution of byproducts was monitored at the ppb levels by HPLC-FD. This proved that FQs are degraded considerably in these matrices. The degradation rates measured in aqueous soil suspension were higher than in neat soil, but lower than in water solution. A number of different byproducts, identified by HPLC electrospray ionization tandem mass spectrometry ESI-MS/MS after a post-extraction cleanup based on a molecularly imprinted polymer-phase, were formed during the photolytic process. The analysis of the photoproducts shows that on solid matrix (viz. FQs adsorbed on soils) the main photoprocess is the oxidative degradation started from the most labile moiety, the amine side-chain. On the contrary, the two main photodegradative paths observed in solution for this class of molecules, viz. dehalogenation and photosubstitution, are absent or remain only as secondary processes in the case of the less reactive FQs (LEV, MOX). The long time required for the photodegradation and the low reactivity make the two latter paths competitive with degradative oxidation, which however remains the predominant path. When a borderline situation is explored, viz. aqueous soil suspensions, our results suggest that the primary photochemical processes are due to soil adsorbed rather than to water dissolved molecules, further underling the strong interaction of FQs with the soil matrix.
    No preview · Conference Paper · Jun 2013
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    ABSTRACT: The photocatalytic reduction of V(V) to V(IV) over TiO2 in aqueous solution is presented. Experiments were undertaken on air-equilibrated water spiked with V(V) (0.6 to 20 mg L-1), under UV-A or solar light. A chemometric study was performed to optimize the reduction yield, by considering the most important variables recognized to affect the photocatalytic process. Among pH, irradiation time and catalyst concentration, the two latter proved to be determinant. The good yields achieved (up to 98%), along with the possibility of working in aerated solution, make this procedure simple, rapid and efficient. Although a deep insight on the photochemical mechanisms was beyond our scope, the role of electron donors was investigated, proving the efficiency of 2-propanol, citric acid and formic acid in the acceleration and improvement of V(V) conversion. After irradiation, total vanadium and aqueous V(V) and V(IV) after solid-phase separation on Chelex-100 resin, were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). The procedure was applied to contaminated wastewaters, combining remediation and possible vanadium recovery as V(IV).
    Full-text · Article · Mar 2013 · Journal of Hazardous Materials
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    ABSTRACT: The widespread presence of fluoroquinolone antibiotics (FQs) in natural ecosystems is a health hazard for humans and other living organisms. The role of sunlight in degrading FQs present in environmental waters has been studied. In particular, the photodegradation of four largely employed FQs, viz. Ciprofloxacin (CIP), Danofloxacin (DAN), Levofloxacin (LEV) and Moxifloxacin (MOX) has been studied in not tampered river water. Degradation rates have been investigated at ppb levels (20-50 μg L(-1)) under solar light, and the results have been commented critically. The products distribution has been studied by HPLC-ESI-MS/MS analysis and structures have been attributed on the basis of their mass fragmentation spectra. Importantly from the environmental point of view, the (potentially toxic) FQ nucleus remained intact over the early stages of the degradation. Indeed, the photoproducts were proved to possess residual antibacterial activity, as shown from in vitro antibacterial activity tests against different well characterized human and environmental bacterial strains, carried out on the above FQs, as well as for Enrofloxacin (ENR) and Marbofloxacin (MAR).
    Full-text · Article · Aug 2012 · Water Research
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    ABSTRACT: Here we describe the extraction from soil of the major photo-transformation products (PTPs) of enrofloxacin (ENR) and danofloxacin (DAN), two fluoroquinolones (FQs) widely used in veterinary medicine and of growing environmental concern, because their PTPs have been shown to retain high antibacterial activity. The microwave-assisted extraction (MAE) technique developed previously for determination of FQs, and based on use of an alkaline aqueous solution of Mg(2+) as a complexing agent for the analytes, was applied to agricultural soil samples fortified with different amounts of the PTPs and residues of the parent compounds (53-1000 ng g(-1) for ENR, 24-148 ng g(-1) for DAN). The PTPs, obtained by irradiation of thin layers of the two drugs, were, after extraction, separated and quantified by HPLC-FD. Good recovery (70-130%) and precision (RSDs 1-6% for repeatability and 9-22% for reproducibility) were obtained by use of the overall analytical procedure. The method was applied for the first time to study the in-soil lifecycle of ENR and DAN PTPs, generated in the matrix by irradiation under natural sunlight, at environmentally significant concentrations. Results indicated that soil-adsorbed FQ PTPs are themselves liable to photodegradation and have lifetimes comparable with those of parent compounds.
    Full-text · Article · Jul 2012 · Analytical and Bioanalytical Chemistry
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    ABSTRACT: The photodegradation of some among the most frequently prescribed fluoroquinolone antibacterials (FQs) was investigated in untreated river water under solar light as well as under the same conditions in the presence of suspended TiO2. The drugs considered included ciprofloxacin (CIP), danofloxacin (DAN), enrofloxacin (ENR), levofloxacin (LEV), marbofloxacin (MAR) and moxifloxacin (MOX), the last two belonging to the most recent FQ generation. The experiments were carried out in lab-scale batch reactor at concentrations (20–50 �g L−1) comparable to those actually measured in surface waters, and the course of the reaction was monitored by high pressure liquid chromatography (HPLC) with fluorescence detector (FD). A first order kinetics was obeyed upon both direct photolysis and TiO2 heterogeneous photocatalysis. The photoproduced intermediates were identified by HPLC with electrospray ionization tandem mass spectrometry (ESI-MS/MS) and the degradation paths were identified. It was concluded that direct irradiation caused fluorine substitution and reductive elimination, while photocatalysis caused oxidative degradation of the amine side-chain (most efficient with tertiary amines and five-membered cyclic amines). The latter one was a minor process upon direct photolysis and involved hydrogen abstraction by excited states or photoproduced radicals. Photocatalytic decomposition occurred at a rate from two to five times faster than direct photolysis for all of the drugs, except for CIP, that is roughly proportional to the amine oxidation potential. The kinetic constants ranged from 0.061 to 0.66 min−1 in direct photolysis, from 0.22 to 2.78 min−1 in the presence of TiO2. In the latter process, a 90% abatement of the concentration of these otherwise highly persistent drugs was obtained in ca. 15 min. This supports the contention that TiO2 photocatalysis under solar light is a convenient and efficient method for the remediation of pollutants at the �g L−1 levels despite the presence of other non-target matrix constituents. Noteworthy, TiO2 side-chain photo-oxidation was equally effective in the further degradation of the primary intermediates at a rate comparable to that of the parent compounds. The degradation proceeded further so that it could be expected that the antimicrobial activity, related to the FQ quinolone core more than to the substituent pattern, could be effectively eliminated.
    Full-text · Article · May 2012 · Applied Catalysis B Environmental