Valentina Santoro

Click-based porous cationic polymers for enhanced carbon dioxide capture

Imidazolium-based porous cationic polymers were synthesized using an innovative and facile approach, which takes advantage of the Debus–Radziszewski reaction to obtain meso-/microporous polymers following click-chemistry principles. In the obtained set of materials, click-based porous cationic polymers have the same cationic backbone, whereas they bear the commonly used anions of imidazolium poly(ionic liquid)s. These materials show hierarchical porosity and a good specific surface area. Furthermore, their chemical structure was extensively characterized using ATR-FTIR and SS-NMR spectroscopies, and HR-MS. These polymers show good performance towards carbon dioxide sorption, especially those possessing the acetate anion. This polymer has an uptake of 2 mmol g−1 of CO2 at 1 bar and 273 K, a value which is among the highest recorded for imidazolium poly(ionic liquid)s. These polymers were also modified in order to introduce N-heterocyclic carbenes along the backbone. Carbon dioxide loading in the carbene-containing polymer is in the same range as that of the non-modified versions, but the nature of the interaction is substantially different. The combined use of in situ FTIR spectroscopy and micro-calorimetry evidenced a chemisorption phenomenon that brings about the formation of an imidazolium carboxylate zwitterion.

The role of direct photolysis and indirect photochemistry in the environmental fate of ethylhexyl methoxy cinnamate (EHMC) in surface waters

The aquatic environmental fate of ethylhexyl methoxy cinnamate (EHMC), one of the most used UVB filters worldwide, was studied by assessing its environmental persistence and photoinduced transformations. The role of direct and indirect photolysis was evaluated. Direct photolysis was shown to play a key role, and this process is expected to be the main attenuation route of EHMC in sunlit surface waters. In contrast, the reaction with OH radicals would be negligible and that with (3)CDOM* would at most be a secondary process. The measurement of the quantum yield of direct photolysis and of the rate constants of reaction with photogenerated transient species (or, sometimes, the use of reasonable values for the latter) allowed the prediction of the EHMC half-life time in surface waters, by means of a validated photochemical model. The predicted EHMC lifetime is of the order of hours to a few days in fair-weather summertime, and the main factors controlling the EHMC phototransformation in sunlit surface waters would be the water depth and the dissolved organic carbon (DOC) content. The formation of transformation products (TPs) was followed as well via HPLC/HRMS. Three TPs were detected in the samples exposed to UVA radiation, while one additional TP was detected in the samples exposed to UVB radiation. The detected TPs comprised 4-methoxybenzaldehyde, a hydroxylated derivative and dimeric species. Through the use of heterogeneous photocatalysis with TiO2, seven additional TPs were identified, most of them resulting from the further degradation of primary TPs formed through direct photolysis and that might be detected in aquatic systems as well. The photodegradation of EHMC in the presence of TiO2 yielded more toxic TPs than the parent compound (as determined with the Vibrio fischeri Microtox assay). The increased toxicity is partially accounted for by the formation of 4-methoxybenzaldehyde.

Photoinduced transformation of pyridinium-based ionic liquids, and implications for their photochemical behavior in surface waters

The photochemical reactivity of three ionic liquids (1-ethylpyridinium tetrafluoroborate, 1-butyl-4-methylpyridinium tetrafluoroborate, and 1-(3-cyanopropyl)pyridinium chloride) was studied by combining laboratory experiments and photochemical modeling, to get insight into the possible behavior in surface-water environments. Among the studied compounds, phototransformation in sunlit surface waters could be an important attenuation pathway for 1-butyl-4-methylpyridinium tetrafluoroborate (BMPOTFB). In this case the reaction with the carbonate radicals (CO3-) would prevail at low values of the dissolved organic carbon (DOC), while the direct photolysis would be important at intermediate to high DOC values. The sensitization by the triplet states of chromophoric dissolved organic matter could play a significant role at high DOC, especially in the presence of a considerable fraction of highly photoreactive pedogenic organic matter derived from soil runoff. The main processes that account for the phototransformation of BMPOTFB and produce the main detected transformation products (TPs) are hydroxylation, detachment/shortening of the butyl chain and double bond formation. Interestingly, there is a considerable overlap between the TPs formed by direct photolysis and those produced by indirect photochemistry. Some of the TPs formed from BMPOTFB are more toxic than the parent compound towards Vibrio fischeri bacteria, and account for the increase in toxicity of the irradiated mixtures. Differently from BMPOTFB, in the case of the other two studied ionic liquids the photodegradation would play a negligible role in environmental attenuation, with the possible exception of very shallow waters with low DOC.

Assessment of the photocatalytic transformation of pyridinium-based ionic liquids in water

We studied some ionic liquids (ILs) belonging to the pyridinium class under photocatalytic treatment. In particularly, we analysed how the length of the alkyl chain, the kind of inorganic ion and the type of substituents could influence the disappearance rate, the mineralization extent, the acute toxicity and the transformation mechanism. For such, we selected some pyridinium derivatives with different alkyl chain but the same anion, namely tetrafluoroborate (1-ethylpyridinium, 1-butylpyridinium, 1-hexylpyridinium), with two alkyl substituents (4-methyl-1-butylpyridinium) and with a different substituent (1-cyanopropylpyridinium). Then, on a selected IL (1-butylpyridinium), we evaluate the role of different inorganic anions (bromine and chlorine). The results show that irrespective to the alkyl chain or the number of substituents, the transformation involved an attack to the alkyl chain, proceeded through the formation of harmless compounds and the mineralization was easily achieved within 4h. Nitrogen was mainly released as ammonium ion. When introducing a cyano group, the extent of nitrate ions and the number of possible transformation route increased. Conversely, the type of inorganic ion deeply affected the transformation pathways and the extent of mineralization. Actually, in the presence of bromide as anion, IL was only partially mineralized and the formation of highly persistent transformation products occurred.

Iodinated X-ray contrast agents: Photoinduced transformation and monitoring in surface water

Conventional wastewater treatment methods have shown to be unsuitable for a complete elimination of iodinated X-ray contrast agents (ICMs), which have thus been found in wastewater treatment plant (WWTP) effluent and in surface water. Once in the surface water, they could be transformed through different processes and form several transformation products that may need to be monitored as well. To this end, we studied the abatement and transformation of ICMs by combining laboratory experiments with in field analyses. We irradiated different aqueous solutions of the selected pollutants in the presence of TiO2 as photocatalyst, aimed to promote ICMs degradation and to generate photoinduced transformation products (TPs) similar to those occurring in the environment and effluent wastewater. This experimental strategy has been applied to the study of three ICMs, namely iopromide, iopamidol and diatrizoate. A total of twenty-four, ten, and ten TPs were detected from iopamidol, diatrizoate and iopromide, respectively. The analyses were performed using a liquid chromatography-LTQ-FT-Orbitrap mass spectrometer. The mineralization process and acute toxicity evolution were assessed as well over time and revealed a lack of mineralization for all ICMs and the formation of harmful byproducts. After characterizing these transformation products, WWTP effluent and surface water taken from several branches of the Chicago River were analyzed for ICMs and their TPs. HRMS with MS/MS fragmentation was used as a confirmatory step for proper identification of compounds in water and wastewater samples. All three of ICM were detected in the effluent and surface water samples, while no significant amount of TPs were detected.

Antineoplastic drugs determination by HPLC-HRMSn to monitor occupational exposure

The purpose of this study was to develop a simple, direct, multiresidue highly specific procedure to evaluate the possible surface contamination of selected antineoplastic drugs in several hospital environment sites by using wipe test sampling. 5-fluorouracil (5-FU), carboplatin (C-Pt), cyclophosphamide (CYC), cytarabine (CYT), doxorubicin (DOX), gemcitabine (GEM), ifosfamide (IFO), methotrexate (MET), and mitomycin C (MIT) belong to very different chemical classes but show good ionization properties under electrospray ionization (ESI) conditions (negative ion mode for 5-FU and positive ion mode in all other cases). HPLC (high performance liquid chromatography) coupled with HRMS (high resolution mass spectrometry) appears to be the best technique for direct analysis of these analytes, because neither derivatization nor complex extraction procedure for polar compounds in samples is requested prior the analysis. Sample preparation was limited to washing wipes with appropriate solvents. Chromatographic separation was achieved on C18 reversed phase columns. The HPLC-HRMS/MS method was validated in order to obtain robustness, sensitivity and selectivity. LLOQ (lower limit of quantitation) values provided a sensitivity good enough to evidence the presence of the drugs in a very low concentration range (<1 pg/cm(2) ). The method was applied for a study of real wipe tests coming from many areas from a hospital showing some positive samples. The low quantitation limits and the high specificity due to the high resolution approach of the developed method allowed an accurate description of the working environment that can be used to define procedural rules to limit working place contamination to a minimum. Copyright

Evaluating the photocatalytic treatment of stevioside by TiO2 in different aqueous matrices and identification of transformation products

The present study reports the photocatalytic transformation of stevioside, under simulated solar irradiation using TiO2 as a photocatalyst. As a tool of investigating the effect of various aqueous matrices, as well as, the initial stevioside concentration on the variation of the photocatalytic efficiency, a fully nested experimental design was employed. A significant impact on the degradation rate of the sweetener was observed: degradation rate decreases in the order distilled water>river water>lake water, attributed to the increased natural organic matter content of the respective natural water samples. Moreover, the investigation has involved the identification of intermediate compounds, as well as the assessment of mineralization and toxicity evaluation. More than one hundred unknown transformation products, most of them in the form of several isobaric species, were identified. By employing accurate mass determination, we were able to attribute an empirical formula to each species and through MSn analyses we were capable to distinguish several isobaric species. The overall transformation mechanism was assessed and involved the hydroxylation/oxidation of the molecule and the subsequent loss of the glucose units bound to the parent compound.

Characterization and Determination of Interesterification Markers (Triacylglycerol Regioisomers) in Confectionery Oils by Liquid Chromatography-Mass Spectrometry

Interesterification is an industrial transformation process aiming to change the physico-chemical properties of vegetable oils by redistributing fatty acid position within the original constituent of the triglycerides. In the confectionery industry, controlling formation degree of positional isomers is important in order to obtain fats with the desired properties. Silver ion HPLC (High Performance Liquid Chromatography) is the analytical technique usually adopted to separate triglycerides (TAGs) having different unsaturation degrees. However, separation of TAG positional isomers is a challenge when the number of double bonds is the same and the only difference is in their position within the triglyceride molecule. The TAG positional isomers involved in the present work have a structural specificity that require a separation method tailored to the needs of confectionery industry. The aim of this work was to obtain a chromatographic resolution that might allow reliable qualitative and quantitative evaluation of TAG positional isomers within reasonably rapid retention times and robust in respect of repeatability and reproducibility. The resulting analytical procedure was applied both to confectionery raw materials and final products.

HPLC-HRMS for the characterization of transformation products of ionic liquids.

RATIONALE Ionic liquids (ILs) are a subject of active research in the field of alternative solvents. We studied the behaviour of a piperidine IL, 1-butyl-1-methylpiperidinium tetrafluoroborate (BMPA), through the elucidation of its transformation products (TPs) in water. METHODS The transformation pathways of BMPA were investigated using high-performance liquid chromatography (HPLC) combined with a hybrid LTQ-Orbitrap instrument on the basis of mass defect filtering. TPs of BMPA were identified by fragmentation patterns and accurate mass measurements. RESULTS The separation and identification of 32 TPs was achieved. BMPA can be oxidized at different positions in the alkyl chains. The ultimate products corresponds to N-methyl-piperidinium and some byproducts involving ring-opening. Tests of acute toxicity, evaluated with Vibrio Fischeri bacteria, show that BMPA transformation proceeds through the formation of slightly harmful compounds. CONCLUSIONS Results showed that the main transformation pathways of BMPA were alkyl chain hydroxylation/shortening and de-alkylation, and that HPLC/LTQ-Orbitrap can serve as an important analytical platform to gather the unknown TPs of ILs.

MS fragmentation and photocatalytic transformation of nicotine and cotinine

RATIONALE Nicotine and cotinine are, respectively, alkaloids produced mainly by the Solanaceae plant family, especially tobacco, and its most important human metabolite. These compounds are frequently found as contaminants in wastewater or landfill samples and they could be used to evaluate pollution by tobacco use. The aim of this study is to improve the knowledge about possible transformation pathways of nicotine and cotinine. This would help the identification of degradants by using HPLC coupled with a high resolving power mass analyzer (LTQ-Orbitrap). In addition, we evaluated toxicity on bioluminescent photobacteria to indicate possible relationships between the formation of transformation products and their toxic effects. METHODS The transformation of nicotine and cotinine and the formation of intermediate products were evaluated adopting titanium dioxide as photocatalyst. The structural identification of photocatalytic transformation products of these two alkaloids was based on LC/multistage MS experiments. High-resolution MS allowed the elemental composition of these products to be hypothesized. The evolution of toxicity as a function of the irradiation time was also studied using a bioluminescent photobacterium (Vibrio fischeri) test. RESULTS Several products were formed and characterized using HPLC/HRMSn . The main photocatalytic pathways involving nicotine and cotinine appear to be hydroxylation, demethylation and oxidation. Nine degradants were formed from nicotine, including cotinine. Seven degradants were generated from cotinine. There is no transformation product in common between the two studied molecules. CONCLUSIONS The study of photocatalytic degradation allowed us to partially simulate human metabolism and the environmental transformation of the bioactive alkaloid nicotine. We searched for some of the identified transformation products in river water and landfill percolate by solid-phase extraction and HPLC/HRMS and eventually their presence was confirmed. These new findings could be of interest in further metabolism and environmental pollution studies. Copyright