[Show abstract][Hide abstract] 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.
Journal of Photochemistry and Photobiology A Chemistry 02/2015; 299:103. · 2.42 Impact Factor
[Show abstract][Hide abstract] 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.
Photochemical and Photobiological Sciences 06/2014; · 2.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Swine sewage biomass used as electron donor for photocatalytic hydrogen production.•Swine sewage is a low-cost and rewarding sacrificial agent.•No carbon dioxide is released by the process.•Hydrogen gas evolution proceeds also under solar light.
International Journal of Hydrogen Energy 05/2014; · 3.55 Impact Factor
[Show abstract][Hide abstract] 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.
Environmental Science and Pollution Research 09/2013; · 2.76 Impact Factor
[Show abstract][Hide abstract] 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+  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.
XIV Congresso Nazionale di Chimica dell’Ambiente e dei Beni Culturali, At Rimini (RN) - Italy; 06/2013
[Show abstract][Hide abstract] 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.
XIV Congresso Nazionale di Chimica dell’Ambiente e dei Beni Culturali, At Rimini (RN) - Italy; 06/2013
[Show abstract][Hide abstract] 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).
Journal of Hazardous Materials 03/2013; · 4.33 Impact Factor
[Show abstract][Hide abstract] 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).
Water Research 08/2012; 46(17):5575-82. · 4.66 Impact Factor
[Show abstract][Hide abstract] 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.
Analytical and Bioanalytical Chemistry 07/2012; 404(5):1565-9. · 3.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This article presents the first results demonstrating that total silicon trace concentration in human ventricular whole blood may be used as a further marker in the diagnosis of drowning. The difference in silicon content between the left and right ventricles was significantly higher for drowning cases than that from individuals who had not drowned. These findings were in full agreement with autoptic responses, supporting silicon as a marker of freshwater drowning. The procedure entails an alkaline microwave-assisted digestion using tetramethylammonium hydroxide (TMAH) in the presence of H(2)O(2) followed by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) detection, whose accuracy was obtained for Seronorm whole blood reference material. Satisfactory recoveries (91-98%) were gained on whole ventricular blood, with a silicon content lower than the method detection limit (MDL), spiked at 5 to 7μgg(-1) with materials consistent with drowning media constituents, that is, freshwater plankton (CRM [certified reference material] 414), silicon dioxide, diatomaceous earth powder, and a silicon standard solution. Good within-lab reproducibility (4-10%) and sensitivity (MDL=0.46μgg(-1)) were achieved as well. The procedure was applied to blood samples from 18 different real cases of death.
[Show abstract][Hide abstract] 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.
Applied Catalysis B Environmental 01/2012; 119-120:32-39. · 5.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Marbofloxacin (MAR) and Enrofloxacin (ENR), two largely employed veterinary Fluoroquinolones (FQs), were found to be present at the micrograms per kilogram level in agricultural soils of South Lombardy (Italy) several months after manuring. Distribution coefficients (K(d)) from sorption experiments indicated a strong binding to the soil. Soil samples fortified with environmentally significant FQs amounts (0.5 mg kg(-1)) were exposed to solar light that promoted extensive degradation (80%) of both drugs in 60-150 h. Thus, photochemistry could be considered a significant depollution path in the soil, although it was two orders of magnitudes slower than in aqueous solution and a fraction of the drug (ca. 20%) remained unaffected. For MAR the photoprocess was the same as in solution, and involved cleavage of the tetrahydrooxadiazine ring. On the contrary, with ENR only some of the photoproducts determined in water (those arising from a stepwise oxidation of the piperazine side chain) were observed. Substitution of the 6-fluoro by a hydroxyl group and reduction did not occur in the soil, supporting the previous contention that such processes required polar solvation of FQs. Consistently with this rationalization, the irradiation of thin layers of solid drugs led to essentially the same products distribution as in the soil. From the environmental point of view it is important to notice that photodegradation mainly affects the side-chains, while the fluoroquinolone ring, to which the biological effect is associated, is conserved up to the later stages of the degradation.
[Show abstract][Hide abstract] ABSTRACT: We present a critical review of the analytical procedures proposed in the past decade for the determination of fluoroquinolones (FQs) by chromatographic methods in solid environmental matrices. We emphasize the overall analytical procedure, from sampling to final detection. We devote special attention to sample preparation, highlighting the problems involved in the analysis of real complex matrices, mainly soil, sediment, manure and sludge. We compare the different extraction techniques in terms of efficiency, time taken and environmental impact, pointing out advantages and drawbacks. We provide an overview on the role of photochemistry in the degradation of FQs in soils and sediments, and we underline the central position of analytical chemistry in environmental monitoring because FQs are emerging pollutants.
[Show abstract][Hide abstract] ABSTRACT: Presented hereafter is a novel method entailing solvent free microwave-assisted extraction (MAE) and HPLC equipped with Fluorimetric Detector (HPLC-FD) for the simultaneous determination at μgkg(-1) concentration of eight fluoroquinolone antibiotics (FQs) (Ciprofloxacin, Danofloxacin, Enrofloxacin, Flerofloxacin, Levofloxacin, Marbofloxacin, Norfloxacin and Orbifloxacin) in agricultural soils. The extraction was quantitatively performed, in a single step, by using an aqueous solution containing Mg(II) as complexing agent, thus avoiding consumption of organic solvents. The optimal MAE conditions have been established through a chemometric approach by considering temperature, irradiation time and matrix moisture or solvent, as the most important recognized variables affecting the extraction yield. Satisfying recoveries (69-110%, spikes 0.03-0.5mgkg(-1)) were gained with a single MAE cycle of 20min, at 80°C in 20% (w/v) Mg(NO(3))(2) solution as leaching agent. MAE-SPE recoveries at 10μgkg(-1), concentration near method quantification limits (MQLs), were in the range 60-85%. Good repeatability and within-lab reproducibility were observed (both in the range 1-16%). The applicability of the method to real samples was assessed on natural contaminated soils. Compared to ultrasonic-assisted extraction (UAE), MAE was shown to be highly competitive in terms of extraction efficacy and analysis speed.
Journal of Chromatography A 09/2010; 1217(47):7316-22. · 4.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The photochemical fate of Marbofloxacin (MAR) and Enrofloxacin (ENR), two Fluoroquinolones (FQs) largely used as veterinary bactericides known to be present in surface waters, was investigated in aqueous solution. The degradation of these pollutants (5-50 microg L(-1) starting concentration) was complete in about 1 h by exposure to solar light (summer) and obeyed a first-order kinetics. The structure of the primary photoproducts was determined. Those from ENR arose through three paths, namely, oxidative degradation of the piperazine side-chain, reductive defluorination, and fluorine solvolysis. More heavily degraded products that had been previously reported were rationalized as secondary photoproducts from the present ones. As for MAR, this underwent homolytic cleavage of the tetrahydrooxadiazine moiety to give two quinolinols. All of the primary products were themselves degraded in about 1 h. The photoreactions rates were scarcely affected by Ca(2+) (200 mg L(-1)), Mg(2+) (30 mg L(-1)), Cl(-) (30 mg L(-1)), and humic acid (1 mg L(-1)), but increased in the presence of phosphate (20 mg L(-1)). The fastest degradation of ENR occurred at pH about 8 where the zwitterionic form was present, while in the case of MAR the cationic form was the most reactive.
Environmental Science and Technology 06/2010; 44(12):4564-9. · 5.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this review is to provide a general overview on the analytical methods proposed in the last decade for trace fluoroquinolone (FQ) determination in environmental waters. A large number of studies have been developed on this topic in reason of the importance of their monitoring in the studies of environmental mobility and potential degradation pathways. Every step of the analysis has been carefully considered, with a particular attention to sample preparation, in relationship with the problems involved in the analysis of real matrices. The different strategies to minimise interference from organic matter and to achieve optimal sensitivity, especially important in those samples with lower FQ concentrations, were also highlighted. Results and progress in this field have been described and critically commented. Moreover, a worldwide overview on the presence of FQs in the environmental waters has been reported.
Journal of Separation Science 02/2010; 33(8):1115-31. · 2.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A method based on selective sequential dissolutions is proposed to determine total vanadium(V) in particulate matter of emissions and working areas at concentrations 1,000 times lower than the threshold limit of 0.05 mg m(-3). Separation and preconcentration of vanadium(V) has been achieved by solid-phase extraction on Chelex 100 resin. Possible influence of the matrix has been investigated for two standard reference materials (SRMs), NIST SRM 1648 and BCR-038, before and after spiking, with vanadium(V) recovery in the range 97-103%.
Analytical and Bioanalytical Chemistry 11/2009; 397(1):395-9. · 3.66 Impact Factor