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Oxygen reduction reaction (ORR) is a crucial process that drives the operation of several energy storage devices. ORR can proceed on the neat carbon surface in the absence of a catalyst, and its electrochemical activity is determined by its microstructure and chemical composition. Oxygen functional groups unavoidably existing on the carbon surface can serve as adsorption sites for ORR intermediates; the presence of some oxygen functionalities gives rise to an increase in the density of electronic states (DOS) at the Fermi level (FL). Both factors should have a positive impact on the electron transfer rate that was demonstrated for ORR in aqueous media. To study the O-groups effect on the aprotic ORR, which is now of interest due to the extensive development of aprotic metal-air batteries, we use model oxidized carbon electrodes (HOPG and single-layer graphene). We demonstrate that oxygen functionalities (epoxy, carbonyl, and lactone) do not affect the rate of one-electron oxygen reduction in aprotic media in the absence of metal cations since their introduction practically does not increase DOS at FL. However, in Li+-containing electrolytes, oxygen groups enhance both the rate of second electron transfer and carbon degradation due to its oxidation by LiO2 yielding carbonate species.

The hydrothermal synthesis of the perovskites NaNbO3, NaTaO3 and the intermediate composition NaNb0.5Ta0.5O3, as CO2 conversion photocatalysts is reported. Among them, the niobate shows the most promising performance under UV irradiation not only in terms of conversion and light utilization ability, but also regarding the selectivity towards CO2 reduction against hydrogen evolution from water protons. Further modification of NaNbO3 with silver as co-catalyst results in an increase of the selectivity towards highly reduced products, primarily methanol, against the carbon monoxide production mainly observed with the bare semiconductor. A thorough structural, electronic, electrochemical characterization, together with in-situ surface analysis by APXPS, was undertaken to gain deeper insight into the reasons that account for such changes. On the one hand, for the bare semiconductors, increased light absorption and the sole presence of Nb in +4 state at the surface seem to drive the superior activity of NaNbO3. On the other hand, electronic and surface chemistry modifications induced by 0.1 wt.% silver deposition are proposed to govern the higher selectivity towards methanol. Excessive metal loading, in turn, enhances the selectivity effect but at the expense of conversion, in such a way that light utilization becomes poorer than with the bare niobate.

We present a highly selective and active Pd carbon catalyst prepared by an easy hydrothermal synthesis method. This synthetic procedure allows the stabilization under mild conditions of interstitial carbon atoms on the surface of a Pd carbon catalyst. The so formed Pd carbide phase appears on the upper surface layers of the Pd carbon catalyst, as demonstrated by X-ray photoelectron depth profile analysis using variable synchrotron X-ray energies. The presence of carbon in the palladium carbide species modifies the electronic state of surface Pd atoms, resulting in more electron positive Pd species (Pd). This influences the adsorption of reactants and reaction intermediates during the hydrogenation of alkynes, dienes and imines, resulting in high selectivities at practically 100% conversion., Funding: The research leading to these results has received funding from the Spanish Ministry of Science, Innovation and Universities through “Severo Ochoa” Excellence Programme (SEV-2016-0683) and the PGC2018-097277-B-100 project. The authors also thank the Microscopy Service of UPV for kind help on measurements. A. García-Ortiz thanks “Severo Ochoa” Programme (SEV-2016-0683) for a predoctoral fellowship. J. Cored thanks the Spanish Government (MINECO) for a “Severo Ochoa” grant (BES-2015-075748). D. R. thanks European Research Council project SYNCATMATCH (671093). The NAP-XPS experiments were performed at the NAPP branch of the CIRCE beamline at the ALBA Synchrotron with the collaboration of ALBA staff.

The development of sustainable processes for CO2 reduction to fuels and chemicals is one of the most important challenges to provide clean energy solutions. The use of sunlight as renewable energy source is an interesting alternative to power the electron transfer required for artificial photosynthesis. Even if redox sites are mainly responsible for this process, other reactive acidic/basic centers also contribute to the overall reaction pathway. However, a full understanding of the CO2 photoreduction mechanism is still a scientific challenge. In fact, the lack of agreement on standardized comparison criteria leads to a wide distribution of reported productions, even using the same catalyst, which hinders a reliable interpretation. An additional difficulty is ascertaining the origin of carbon-containing products and effect of surface carbon residues, as well as the reaction intermediates and products under real dynamic conditions. To determine the elusive reaction mechanism, we report an interconnected strategy combining in-situ spectroscopies, theoretical studies and catalytic experiments. These studies show that CO2 photoreduction productions are influenced by the presence of carbon deposits (i.e. organic molecules, carbonates and bicarbonates) over the TiO2 surface. Most importantly, the acid/base character of the surface and the reaction medium play a key role in the selectivity and deactivation pathways. This TiO2 deactivation is mainly initiated by the formation of carbonates and peroxo- species, while activity can be partially recovered by a mild acid washing treatment. We anticipate that these findings and methodology enlighten the main shadows still covering the CO2 reduction mechanism, and, most importantly, provide essential clues for the design of emergent materials and reactions for photo(electro)catalytic energy conversion.

fff; International audience; Mo/TiO2 catalysts with atomic dispersion of molybdenum appear active and stable in the gas-phase hydrogenation of CO2. The comparison between various titania materials shows a crucial effect of the support surface structure on the methanol yield. Molybdenum supported at low coverage on rutile titania nanorods is the most active and methanol-selective system. From catalyst characterization by aberration-corrected scanning transmission electron microscopy, near-ambient pressure X-ray photoelectron spectroscopy, diffuse reflectance UV-vis spectroscopy, and temperature-programmed techniques, we suggest that the most active catalysts for methanol production involve atomically-dispersed oxomolybdate species with high reducibility and strong interaction with the rutile support.

The strong metal–support interaction (SMSI) effect plays a central role in catalysis by decreasing the catalytic activity or even improving it in some specific cases. In spite of the intense resear...

Water dissociation on oxides is of great interest because its fundamental aspects are still not well understood and it has implications in many processes, from ferroelectric polarization screening phenomena to surface catalysis and surface chemistry on oxides. In situ water dissociation and redox processes on metal oxide perovskites which easily expose TiO2-terminated surfaces, such as SrTiO3, BaTiO3 or Pb(Zr,Ti)O3, are studied by ambient pressure XPS, as a function of water vapour pressure. From the analysis of the O1s spectrum, we determine the presence of different types of oxygen based species, from hydroxyl groups, either bound to Ti4+ and metal sites or lattice oxygen, to different peroxide compounds, and propose a model for the adsorbate layer composition, valid for environmental conditions. From the XPS analysis, we describe the existing surface redox reactions for metal oxide perovskites, occurring at different water vapour pressures. Among them, peroxide species resulting from surface oxidative reactions are correlated with the presence of Ti4+ ions, which are observed to specifically promote surface oxidation and water dissociation as compared to other metals. Finally, surface peroxidation is enhanced by X-ray beam irradiation, leading to a higher coverage of peroxide species after beam overexposure and by ferroelectric polarization, demonstrating the enhancement of the reactivity of the surfaces of ferroelectric materials due to the effect of internal electric fields., The authors would like to acknowledge Prof. P. Paruch of Université de Genève, who kindly provided PZT thin film samples and Prof. B. Noheda for kindly providing BFO thin films. Financial support was provided by the Spanish Ministerio de Economía y Competitividad (MINECO) under projects FIS2015-73932-JIN and MAT2016-77852-C2-1-R (AEI/FEDER, UE). ICN2 is supported by the Severo Ochoa program from Spanish MINECO (Grant No. SEV-2017-0706), and ICMAB acknowledges support from the Severo Ochoa Program of MINECO (Grant No. SEV-2015-0496). This work was partially funded by 2017-SGR-579 and 2017-SGR-668 projects from the Generalitat de Catalunya., We acknowledge support of the publication fee by the CSIC Open Access Support Initiative through its Unit of Information Resources for Research (URICI)

In this work, the electronic properties of the metal sites in cubic and monoclinic ZrO2 supported Pd and PdCu catalysts have been investigated using CO as probe molecule in in-situ IR studies, and the surface composition of the outermost layers has been studied by APXPS (Ambient Pressure X-ray Photoemission Spectroscopy). The reaction products were followed by mass spectrometry, making it possible to relate the chemical properties of the catalysts under reaction conditions with their selectivity. Combining these techniques, it has been shown that the structure of the support (monoclinic or cubic ZrO2) affects the metal dispersion, mobility, and reorganization of metal sites under methanol steam reforming (MSR) conditions, influencing the oxidation state of surface metal species, with important consequences in the catalytic activity. Correlating the mass spectra of the reaction products with these spectroscopic studies, it was possible to conclude that electropositive metal species play an imperative role for high CO2 and H2 selectivity in the MSR reaction (less CO formation), The research leading to these results has received funding from European Research council project SYNCATMATCH (671093) and from Spanish Ministry of Science, Innovation and Universities with the project “I + D + I research challenges (RTI2018-099668-B-C21)”. This work also was financially supported by: Base Funding-UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology and Energy—LEPABE-funded by national funds through the FCT/MCTES (PIDDAC); European Union’s Seventh Framework Program (FP/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement no. 303476.

Surface segregation and restructuring in size-selected CuNi nanoparticles were investigated via near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) at various temperatures in different gas environments. Particularly in focus were structural and morphological changes occurring under CO2 hydrogenation conditions in the presence of carbon monoxide (CO) in the reactant gas mixture. Nickel surface segregation was observed when only CO was present as adsorbate. The segregation trend is inverted in a reaction gas mixture consisting of CO2, H2, and CO, resulting in an increase of copper concentration on the surface. Density functional theory calculations attributed the inversion of the segregation trend to the formation of a stable intermediate on the nanocatalyst surface (CH3O) in the CO-containing reactant mixture, which modifies the nickel segregation energy, thus driving copper to the surface. The promoting role of CO for the synthesis of methanol was demonstrated by catalytic characterization measurements of silica-supported CuNi NPs in a fixed-bed reactor, revealing high methanol selectivity (over 85%) at moderate pressures (20 bar). The results underline the important role of intermediate reaction species in determining the surface composition of bimetallic nanocatalysts and help understand the effect of CO cofeed on the properties of CO2 hydrogenation catalysts.

An easy and effective analytical method was developed for the simultaneous quantification of four tocopherols (Ts) and four tocotrienols (T3s) in three pecan nut cultivars (Stuart, Sioux, and Pawnee). The analytes were separated on a C30 column kept at 15 °C, under isocratic non-aqueous reversed-phase (NARP) conditions, in only 18 min and detected by atmospheric pressure chemical ionization–tandem mass spectrometry (APCI-MS/MS). The HPLC-APCI-MS/MS method was validated, according to the main FDA guidelines, and then applied for the characterization of the real samples. Analytes were extracted by cold saponification with recoveries greater than 87%. The limits of detection (LOD) and limits of quantification (LOQ) were in the range of 0.3–10 μg/100 mg and 1–30 μg/100 mg, respectively. Compared to other nuts, vitamin E composition of pecan nuts (Carya illinoinensis) has only partially been elucidated. Results have evidenced the prevalence of γ-forms for both Ts and T3 s and clear quantitative differences of the identified vitamers among the studied cultivars. The richest variety in vitamin E was Sioux with a total content of about ∼ 32 mg/100 g wet weight, followed by Stuart (∼16 mg/100 g) and Pawnee (∼9 mg/100 g).

One-dimensional (1D) nanostructured surfaces based on high-density arrays of nanowires and nanotubes of photoactive titanium dioxide (TiO2) present a tunable wetting behavior from superhydrophobic to superhydrophilic states. These situations are depicted in a reversible way by simply irradiating with ultraviolet light (superhydrophobic to superhydrophilic) and storage in dark. In this article, we combine in situ environmental scanning electron microscopy (ESEM) and near ambient pressure photoemission analysis (NAPP) to understand this transition. These experiments reveal complementary information at microscopic and atomic level reflecting the surface wettability and chemical state modifications experienced by these 1D surfaces upon irradiation. We pay special attention to the role of the water condensation mechanisms and try to elucidate the relationship between apparent water contact angles of sessile drops under ambient conditions at the macroscale with the formation of droplets by water condensation at low temperature and increasing humidity on the nanotubes' surfaces. Thus, for the as-grown nanotubes, we reveal a metastable and superhydrophobic Cassie state for sessile drops that tunes toward water dropwise condensation at the microscale compatible with a partial hydrophobic Wenzel state. For the UV-irradiated surfaces, a filmwise wetting behavior is observed for both condensed water and sessile droplets. NAPP analyses show a hydroxyl accumulation on the as-grown nanotubes surfaces during the exposure to water condensation conditions, whereas the water filmwise condensation on a previously hydroxyl enriched surface is proved for the superhydrophilic counterpart., We thank the Junta de Andalucia (TEP8067, FQM-196, and P12-FQM-2265), the European Regional Development Funds program (EU-FEDER), and the AEI and MINECO (projects MAT2013-40852-R, MAT2013-42900-P, MINECO-CSIC 201560E055, and MAT2016-79866-R) for financial support

Photocatalytic performance is highly dependent on the nature and dispersion of the active sites, playing a crucial role in the optoelectronic and charge-transfer processes. Here, we report stabilized isolated iron on MCM-41 as a highly active catalyst for a photoredox reaction. The unique nature of the single-atom centers exhibit a trichloroethylene conversion per iron site that is almost 5 times higher than that of TiO2. Advanced characterization and theoretical calculations indicate the generation of hydroxyl radicals, through a photoinduced ligand-to-metal charge-transfer mechanism, which act as hole scavengers that lead to the formation of intermediate oxo–iron species (Fe═O). This intermediate species is the key step in promoting the photocatalytic reactions. Understanding the mechanistic photoredox pathway in isolated active site materials is imperative for developing highly efficient nonprecious photocatalysts for environmental or energy applications.

Background : The occurrence of systemic infections due to C. albicans has increased especially in critically ill patients. In fungal infections, secretory mechanisms are key events for disease establishment. Recent findings demonstrate that fungal organisms release many molecular components to the extracellular space in extracellular vesicles. Aims: We develop a method to obtain exosomes from yeast cultures of the Candida albicans . Methods : Yeast strains used in this work were C. albicans SC5314, C. parapsilosis (ATCC 22019) and C. krusei (ATCC 6258). Yeasts were grown at 37.º in liquid YPD medium. The cell cultures were centrifuged and the supernatant filtered through sterile nitrocellulose. Filtrates were concentrated and centrifuged using an ultracentrifuge. The sediment was analyzed by electron microscopy of transmission. Results: The transmission of electron microscopy and nanoparticle tracking analysis confirmed the presence of extracellular vesicles (exosomes) of sizes between 100 and 200 nm and the absence of cellular contaminants. This was ratified by the characterization of proteins performed through the western blot technique, where the absence of cell contamination in the preparations was assessed. Conclusions: The method proves to be highly effective due to the homogeneity and purity of the obtained microvesicles. The protocol developed in this paper proves to be effective for obtaining exosomes of other Candida species, which will allow future studies to determine its protein composition and the role that these vesicles can play. Contexto: La aparición de infecciones sistémicas por C. albicans ha aumentado sobre todo en pacientes graves. En las infecciones fúngicas, los mecanismos de secreción son eventos clave para que el establecimiento de la enfermedad. Hallazgos recientes demuestran que los organismos fúngicos liberan muchos componentes moleculares al espacio extracelular en vesículas extracelulares. Objetivos: Desarrollamos un método para obtener exosomas de cultivos de levadura de Candida albicans . Métodos: Las cepas de levadura que se usaron en este trabajo son C. albicans SC5314, C. parapsilosis (ATCC 22019) y C. krusei (ATCC 6258). Las levaduras se cultivaron a 37.º C en un medio YPD líquido. Los cultivos de células fueron centrifugados y el sobrenadante, filtrado por medio de nitrocelulosa estéril. Los filtrados se concentraron y centrifugaron usando una ultracentrifugadora. El sedimento fue analizado por un microscopio electrónico de transmisión. Resultados: La microscopía electrónica de transmisión y el análisis de nanopartículas confirman la presencia de vesículas extracelulares (exosomas) de un tamaño entre 100 y 200 nm, así como la ausencia de contaminantes celulares. Esto se ratificó mediante la caracterización de proteínas obtenidas por medio de la técnica de Western blot, donde se evaluó la ausencia de contaminación celular en las preparaciones. Conclusiones: El método es altamente eficaz dada la homogeneidad y la pureza de las microvesículas obtenidas. El protocolo desarrollado en este artículo demuestra ser efectivo para obtener exosomas de otras especies Candida , lo que permitirá que en futuros estudios se determine su composición proteica y el papel que estas vesículas pueden desempeñar. Ciencias Experimentales

Perovskite materials are typically used as oxygen electrodes of solid oxide fuel and electrolysis cells (SOC). The high stability of the perovskite structure in oxidative environments makes it a good candidate as a cathode electrode for steam electrolysis SOC as well. In this work, we investigate SOC with La0.75Sr0.25Cr0.9Fe0.1O3 perovskite cathodes employing near ambient pressure X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopies combined with online electrochemical measurements. Based on operando experimental evidences the surface state of the perovskite electrode is directly associated with the electrocatalytic performance of the cell. The results indicate that under steam electrolysis operating conditions the well-known Sr surface enrichment is accompanied by Cr segregation and formation of SrCrO4-like oxide. In contrast to the common perception of the role of surface chromites, we show here that its presence does not induce cell deactivation, but on the contrary, is beneficial for cell performance.

Usually, nanoparticle synthesis methodologies require the use of organic molecules (capping agent, solvent molecules, etc.), which results in carbon deposits on the nanoparticle surface. These residues modify the surface properties mainly affecting the catalytic behavior. In this work, unsupported poly(vinylpyrrolidone) (PVP)-stabilized PtCu (1:3 molar ratio) bimetallic alloy nanoparticles were synthetized and characterized. An alternative surface cleaning method has been designed, which successfully removes the presence of organic fragments. To address this key issue, we have combined a first nanoparticle washing step with a near ambient pressure X-ray photoelectron spectroscopy (NAPXPS) study in order to obtain a clean active site and the total understanding of the carbon elimination mechanism. The dynamic evolution of the surface organic species composition under different gas mixtures at 750 mTorr and 350 °C has been studied, and only under CO2 exposure, NAPXPS analysis revealed a total availability of the active site by the removal of the organic nanoparticle coating. Ministerio de Economía y Competitividad ENE2015-66975-C3-2-R Gobierno de España MAT2012-38567-C02-02

The dynamic behavior of a CuO/ZnO/Ga O catalyst under methanol steam reforming (MSR) reaction conditions promoted by a high dispersion of the copper nanoparticles and defect sites of a nonstoichiometric ZnGa O spinel phase has been observed, where structural changes taking place in the initial state of the reaction determine the final state of the catalyst in stationary reaction conditions. Mass spectrometry (MS) studies under transient conditions coupled to X-ray photoelectron spectroscopy (XPS) have shown copper oxidation to Cu in the initial state of the reaction (TOS = 4 min), followed by a fast reduction of the outer shell to Cu , while keeping dissolved oxygen species in the inner layers of the nanoparticle. The presence of this subsurface oxygen impairs a positive charge to the uppermost surface copper species, that is, Cu , which undoubtedly plays an important role on the MSR catalytic activity. The detection of these features, unperceived by conventional spectroscopic and catalytic studies, has only been possible by combining synchrotron NAP-XPS studies with transient studies performed in a low volume catalytic reactor connected to MS and linked with Raman and laboratory scale XPS studies., The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under Grant Agreement No. [303476]. Part of this work was financially supported by the following projects: (i) Project POCI-01-0145-FEDER-006939 (Laboratory for Process Engineering, Environment, Biotechnology and Energy – UID/EQU/00511/2013) funded by the European Regional Development Fund (ERDF), through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) and by national funds, through FCT - Fundação para a Ciência e a Tecnologia; (ii) NORTE-01-0145-FEDER-000005 – LEPABE-2-ECO-INNOVATION, supported by North Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); and (iii) the Spanish Government-MINECO through “Severo Ochoa” Excellence Programme (SEV-2016-0683). D.R. thanks European Research Council project SYNCATMATCH (671093). J.C. thanks the Spanish Government (MINECO) for a “Severo Ochoa” grant (BES-2015-075748). The NAP-XPS experiments were performed at the NAPP branch of the CIRCE beamline at the ALBA Synchrotron with the collaboration of ALBA staff.

This paper describes an analytical approach, based on LC-diode array detector-MS/MS (LC-DAD-MS/MS), for characterizing the fat-soluble micronutrient fraction in rainbow trout (Oncorhynchus mykiss). Two different procedures were applied to isolate the analytes from liver and muscle tissue: overnight cold saponification to hydrolyze bound forms and to simplify the analysis; matrix solid-phase dispersion to avoid artifacts and to maintain unaltered the naturally occurring forms. Analytes were separated on a C30 analytical column by using a nonaqueous reversed mobile phase compatible with the atmospheric pressure chemical ionization. Compared to other works, the most relevant advantage of the here illustrated method is the large amount of information obtained with few analytical steps: nine fat-soluble vitamins (3,4-dehydroretinol, retinol, cholecalciferol, ergocalciferol, α-tocopherol, γ-tocopherol, δ-tocopherol, phylloquinone, and menaquinone-4) and eight carotenoids (all-trans-lutein, all-trans-astaxanthin, all-trans-zeaxanthin, all-trans-β-cryptoxanthin, all-trans-canthaxanthin, all-trans-ζ-carotene, all-trans-β-carotene, and all-trans-γ-carotene) were quantified after the method validation, while other untargeted carotenoids were tentatively identified by exploiting the identification power of the LC-DAD-MS/MS hyphenation.

Polarization dependence of water adsorption and desorption on LiNbO surfaces was demonstrated using X-ray photoelectron spectroscopy (XPS) carried out in situ under near-ambient conditions. Positive and negative (0001) faces (z-cut) of the same crystal were compared for the same temperature and pressure conditions. Our results indicate a preferential adsorption on the positive face of the crystal with increasing water pressure and also higher desorption temperature of the adsorbed molecular water at the positive face. Adsorption measurements on the (1100) face (y-cut) showed also strong affinity to water, as observed for the z-cut positive surface. We found a direct relation between the capacity of the surface to discharge and/or to screen surface charges and the affinity for water of each face. XPS spectra indicate the presence of OH groups at the surface for all the conditions and surfaces measured., This work has been partially funded by the 2014 SGR 1216 project from the Generalitat de Catalunya, the MAT2012-38319-C02-01, the FIS2013-48668-C2-1-P, and FIS2015- 73932-JIN from the Spanish Ministerio de Economia y Competitividad (MINECO). K.C-E.’s work was funded by an ERC Starting Grant from the EU (Project No. 308023). N.D. is also grateful to MINECO for the “Ramon y Cajal” contract RYC-2010-06365. ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295).

RATIONALE Sulfur-vulcanized rubber is a three-dimensional polymer network, insoluble in all organic solvents. For this reason, vulcanization products are difficult to study and identify by conventional analytical techniques. To simplify this task, low molecular weight olefins have been used as model compounds (MCs) in place of rubber in vulcanization experiments. METHODS In this work, the vulcanization process was investigated using squalene (SQ) as MC. By-products, intermediates and products were separated by semipreparative reversed-phase liquid chromatography (RPLC) with UV detection. Each fraction was collected, concentrated and characterized by flow injection analysis (FIA) and non-aqueous reversed-phase (NARP) LC coupled to positive atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Under the latter conditions, an Information-Dependent Acquisition (IDA) was performed on a linear ion trap mass spectrometer to obtain structural information. RESULTS Several vulcanized compounds containing up to three SQ molecules, cross-linked with chains involving up to 14 sulfur atoms overall, have been identified along with some of their oxidized products (epoxides and hydroperoxides). The FIA-MS spectra showed peak clusters, each of which included two-three subclusters; the interpretation was complicated by the occurrence of more ion species per product, by the unsaturation grade and by the characteristic isotopic distribution of sulfur. The enhanced product ion scan (EPI) spectra, acquired during the IDA experiments, supported the FIA-MS identification allowing one to count the number of sulfur atoms. CONCLUSIONS The sensitivity of the developed analytical strategy was due to the enrichment factor achieved via semipreparative chromatography and the very good response of the APCI detection. Pattern fragmentation and chromatographic behavior simplified the identification of the cured compounds and their oxidized products, whose occurrence was related to the grade of oxidation of SQ used as reagent. Copyright © 2016 John Wiley & Sons, Ltd.

Human milk is the only source of vitamin K for exclusively breastfed neonates. This vitamin is crucial both for blood coagulation (vitamin K 1 ) and for the normal neurological and skeletal development of the foetus and newborn (vitamin K 2 ). Since vitamin K is ubiquitous in foods, deficiency is not common in adults, but plasma levels and hepatic storage are very low at birth. In light of the importance of this valuable micronutrient, a non-invasive method for verifying that exclusively breastfed infants are receiving an adequate supply of the vitamin is clearly a topic of great significance. In spite of this, the determination of the several vitamin K homologues in human milk has still not been completely elucidated. This paper presents an HPLC–MS/MS method for the simultaneous determination of phylloquinone, menaquinone-4 (MK-4), and menaquinone-7 (MK-7) in human milk after a simple and effective isolation procedure. Overnight cold saponification and extraction of the analytes with hexane provided yields above 75%. This procedure, combined with high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS), made it possible to achieve limits of detection (LODs) below 0.8 ng/mL. After a complete validation study, the method was applied to measure vitamin K congeners in several human milk samples; results showed vitamin K 1 concentrations comparable with those reported in the literature. In addition, this is the first study performed for the determination of MK-4 and MK-7 in the maternal milk of Italian women.

In this work, we show that multilayer graphene forms by methanol decomposition at 280 °C on an electrochemically promoted nickel catalyst film supported on a K-βAl2O3 solid electrolyte. In operando near ambient pressure photoemission spectroscopy and electrochemical measurements have shown that polarizing negatively the Ni electrode induces the electrochemical reduction and migration of potassium to the nickel surface. This elemental potassium promotes the catalytic decomposition of methanol into graphene and also stabilizes the graphene formed via diffusion and direct K–C interaction. Experiments reveal that adsorbed methoxy radicals are intermediate species in this process and that, once formed, multilayer graphene remains stable after electrochemical oxidation and back migration of potassium to the solid electrolyte upon positive polarization. The reversible diffusion of ca. 100 equivalent monolayers of potassium through the carbon layers and the unprecedented low-temperature formation of graphene and other carbon forms are mechanistic pathways of high potential impact for applications where mild synthesis and operation conditions are required., En este trabajo mostramos que el grafeno multicapa se forma por descomposición del metanol a 280 °C sobre una película de catalizador de níquel promovida electroquímicamente soportada sobre un K-βAl 2 O 3electrolito sólido. Operando cerca de la espectroscopia de fotoemisión a presión ambiental y las mediciones electroquímicas han demostrado que la polarización negativa del electrodo de Ni induce la reducción electroquímica y la migración del potasio a la superficie del níquel. Este potasio elemental promueve la descomposición catalítica del metanol en grafeno y también estabiliza el grafeno formado a través de la difusión y la interacción directa K-C. Los experimentos revelan que los radicales metoxi adsorbidos son especies intermedias en este proceso y que, una vez formado, el grafeno multicapa permanece estable después de la oxidación electroquímica y la migración de regreso del potasio al electrolito sólido tras la polarización positiva. La difusión reversible de ca.

Leishmaniasis is a poverty-related disease endemic in 98 countries worldwide, with morbidity and mortality increasing daily. All currently used first-line and second-line drugs for the treatment of leishmaniasis exhibit several drawbacks including toxicity, high costs and route of administration. Consequently, the development of new treatments for leishmaniasis is a priority in the field of neglected tropical diseases. The aim of this work is to develop computational models those allow the identification of new chemical compounds with potential anti-leishmanial activity. A data set of 116 organic chemicals, assayed against promastigotes of Leishmania amazonensis, is used to develop the theoretical models. The cutoff value to consider a compound as active one was IC50≤1.5μM. For this study, we employed Dragon software to calculate the molecular descriptors and WEKA to obtain machine learning (ML) models. All ML models showed accuracy values between 82% and 91%, for the training set. The models developed with k-nearest neighbors and classification trees showed sensitivity values of 97% and 100%, respectively; while the models developed with artificial neural networks and support vector machine showed specificity values of 94% and 92%, respectively. In order to validate our models, an external test-set was evaluated with good behavior for all models. A virtual screening was performed and 156 compounds were identified as potential anti-leishmanial by all the ML models. This investigation highlights the merits of ML-based techniques as an alternative to other more traditional methods to find new chemical compounds with anti-leishmanial activity.

In this work we investigate by in-situ near-ambient pressure photoemission (NAPP) spectroscopy the phenomenon of Electrochemical Promotion of Catalysis (EPOC). We studied the reduction and diffusion kinetics of alkaline ions in a solid electrolyte cell formed by a nickel electrode supported on K+-β-alumina electrolyte. Experiments in ultra-high vacuum and in the presence of steam showed that the amount of potassium atoms supplied to the surface is probably affected by nickel electronic modifications induced by adsorbed OH− groups. It was also deduced that part of the segregated potassium would be adsorbed at inner interfaces where it would be inaccessible to the photoelectron analyzer. A migration mechanism of the promoter is proposed consisting in: (i) the electrochemical reduction of the alkali ions (potassium) at the Ni/solid electrolyte/gas interface; (ii) the spillover of potassium atoms onto the Ni gas-exposed surface; and (iii) the diffusion of potassium atoms to Ni inner grain boundary interfaces., En este trabajo investigamos mediante espectroscopía de fotoemisión a presión cercana al ambiente in situ (NAPP) el fenómeno de la Promoción Electroquímica de la Catálisis (EPOC). Estudiamos la cinética de reducción y difusión de iones alcalinos en una celda de electrolito sólido formada por un electrodo de níquel soportado sobre electrolito K + -β-alúmina. Los experimentos en vacío ultraalto y en presencia de vapor mostraron que la cantidad de átomos de potasio suministrados a la superficie probablemente se ve afectada por modificaciones electrónicas de níquel inducidas por OH adsorbido .grupos También se dedujo que parte del potasio segregado sería adsorbido en las interfaces internas donde sería inaccesible para el analizador de fotoelectrones. Se propone un mecanismo de migración del promotor que consiste en: (i) la reducción electroquímica de los iones alcalinos (potasio) en la interfase Ni/electrolito sólido/gas; (ii) el derrame de átomos de potasio sobre la superficie expuesta al gas Ni; y (iii) la difusión de átomos de potasio a las interfaces de límite de grano interno de Ni.

This work describes a new analytical method for the determination of four cobalamins (adenosylcobalamin (AdoCbl), methylcobalamin (MeCbl), hydroxocobalamin (OHCbl) and cyanocobalamin (CNCbl)) in cow's milk. The extraction procedure is fast and based on dilution/protein precipitation of a milk sample with 50mM sodium acetate buffer (pH 4.6), followed by solid phase extraction (SPE) of the filtered supernatant. Relative recoveries higher than 60% have been obtained for all the cobalamins by combining two different types of sorbents in the same SPE cartridge: two disks of buckypaper (BP), a nanoporous felt composed of oxidized multiwalled carbon nanotubes (MWCNTs), separated by a Teflon frit from OASIS HLB (500mg), a hydrophilic-lipophilic balance copolymer. Before its use as sorbent, BP was characterized in terms of porosity, permeability, surface area, specific adsorption capacity and tested for a potential reuse after adequate chemical regeneration. The analysis of the extracts was performed by liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS) on an analytical C18 column in less than 10min. After validation, the method was applied to the determination of the natural content of the four B12 homologues in cow's milk samples, providing data lacking in the literature.

Inorganic clathrate materials are of great fundamental interest and potential practical use for application as thermoelectric materials in freon-free refrigerators, waste-heat converters, direct solar thermal energy converters, and many others. Experimental studies of their electronic structure and bonding have been, however, strongly restricted by (i) the crystal size and (ii) essential difficulties linked with the clean surface preparation. Overcoming these handicaps, we present for the first time a comprehensive picture of the electronic band structure and the chemical bonding for the Sn(24-x-δ)InxAs(22-y)I8 clathrates obtained by means of photoelectron spectroscopy and complementary quantum modeling.

Atmospheric pressure X-ray spectroscopy techniques based on soft X-ray excitation can provide powerful interface-sensitive chemical information about a solid surface immersed in a gas or liquid environment. However, X-ray illumination of such dense phases can lead to the generation of considerable quantities of radical species by radiolysis. Soft X-ray absorption measurements of Cu films in both air and aqueous alkali halide solutions reveal that this can cause significant evolution of the Cu oxidation state. In air and NaOH (0.1 M) solutions, the Cu is oxidized toward CuO, while the addition of small amounts of CH3OH to the solution leads to reduction toward Cu2O. For Ni films in NaHCO3 solutions, the oxidation state of the surface is found to remain stable under X-ray illumination and can be electrochemically cycled between a reduced and oxidized state. We provide a consistent explanation for this behavior based on the products of X-ray-induced radiolysis in these different environments and highlight a number of general approaches that can mitigate radiolysis effects when performing operando X-ray measurements.

The behavior of ternary mixed crystals or solid solutions and its correlation with the properties of their binary constituents is of fundamental interest. Due to their unique potential for application in future information technology, mixed crystals of topological insulators with the spin-locked, gapless states on their surfaces attract huge attention of physicists, chemists and material scientists. (Bi1−xSbx)2Te3 solid solutions are among the best candidates for spintronic applications since the bulk carrier concentration can be tuned by varying x to obtain truly bulk-insulating samples, where the topological surface states largely contribute to the transport and the realization of the surface quantum Hall effect. As this ternary compound will be evidently used in the form of thin-film devices its chemical stability is an important practical issue. Based on the atomic resolution HAADF-TEM and EDX data together with the XPS results obtained both ex situ and in situ, we propose an atomistic picture of the mixed crystal reactivity compared to that of its binary constituents. We find that the surface reactivity is determined by the probability of oxygen attack on the Te–Sb bonds, which is directly proportional to the number of Te atoms bonded to at least one Sb atom. The oxidation mechanism includes formation of an amorphous antimony oxide at the very surface due to Sb diffusion from the first two quintuple layers, electron tunneling from the Fermi level of the crystal to oxygen, oxygen ion diffusion to the crystal, and finally, slow Te oxidation to the +4 oxidation state. The oxide layer thickness is limited by the electron transport, and the overall process resembles the Cabrera–Mott mechanism in metals. These observations are critical not only for current understanding of the chemical reactivity of complex crystals, but also to improve the performance of future spintronic devices based on topological materials.

Thyreostats can be used fraudulently to promote a rapid increase in weight of breeding animals at low cost. Their severe toxicological effects impose the development of reliable analytical methods to be used in monitoring plans. This work describes an alternative approach to isolate residues of thiouracil, methyl-thiouracil, propyl-thiouracil, phenyl-thiouracil, tapazole and mercaptobenzimidazole from bovine muscle tissue. The developed procedure is based on the following three steps: i) matrix solid-phase dispersion with C18 for the preliminary sample preparation; ii) subcritical water extraction (SWE) at 160°C and 100 bar; iii) clean-up on an Oasis HLB cartridge. The quantitative determination was performed by LC-MS/MS in dual polarity ionization by using internal standardization. The SWE-LC-MS/MS method was validated according to the identification criteria of the Commission decision 2002/657/EC. The relative recoveries ranged from 72 to 97%; within-lab reproducibility was less than 18%. The decision limit and the detection capability of all analytes were below the recommended concentration, set at 10 µg kg−1, but the validation results demonstrated that this method could only be applied for screening of thiouracil and methyl-thiouracil. Besides the analytical advantages related to the use of water as solvent extraction, the procedure allowed significant removal of lipids, whose detrimental effects on instrumentation and MS sensitivity are well-known.

Understanding nanoparticle catalysis requires novel approaches in which adjoining crystal orientations can be studied under the same reactive conditions. Here we use a curved palladium crystal and near-ambient pressure X-ray photoemission spectroscopy to characterize chemical species during the catalytic oxidation of CO in a whole set of surfaces vicinal to the (111) direction simultaneously. By stabilizing the reaction at fixed temperatures around the ignition point, we observe a strong variation of the catalytic activity across the curved surface. Such spatial modulation of the reaction stage is straightforwardly mapped through the photoemission signal from active oxygen species and poisoning CO, which are shown to coexist in a transient regime that depends on the vicinal angle. Line-shape analysis and direct comparison with ultrahigh vacuum experiments help identifying and quantifying all such surface species, allowing us to reveal the presence of surface oxides during reaction ignition and cooling-off., We acknowledge financial support from the Spanish Ministry of Economy (Grants MAT-2012-38567-C02-02, MAT-2016-78293-C6, MAT-2017-88374-P) and Basque Government (Grant IT-1255-19).

M/WO3 (M = Pt, Pd) systems formed by a porous WO3 thin film decorated by metal nanoparticles are known for their reversible coloring upon exposure to H2 at room temperature. In this work, this gasochromic behavior is investigated in situ by means of near-ambient photoemission (NAPP). Pt/WO3 systems formed by very small Pt nanoparticles (10 ± 1 nm average size) incorporated in the pores of nanocolumnar WO3 thin films prepared by magnetron sputtering at an oblique angle have been exposed to a small pressure of hydrogen at ambient temperature. The recorded UV¿vis transmission spectra showed the reversible appearance of a very intense absorption band responsible for the blue coloration of these gasochromic films. In an equivalent experiment carried out in the NAPP spectrometer, W 4f, O 1s, Pt 4f, and valence band photoemission spectra have been recorded at various photon energies to follow the evolution of the reduced tungsten species and hydroxyl groups formed upon film exposure to hydrogen. The obtained results are compared with those of a conventional X-ray photoemission study after hydrogen exposure between 298 and 573 K. As investigated by NAPP, the gasochromic behavior at 298 K is accounted for by a reaction scheme in which hydrogen atoms resulting from the dissociation of H2 onto the Pt nanoparticles are spilt over to the WO3 substrate where they form surface OH¿/H2O species and subsurface W5+ cations preferentially located in buried layers of the oxide network., The authors thank the European Regional Development Funds program (EU-FEDER) and the MINECO-AEI (Projects MAT2013-40852-R, 201560E055, and MAT2016-79866-R)) for financial support.

In this study, we estimated the depth profiles of nutrients in the natural wetland “Ciénega Tamasopo” (Central Mexico) located in the Neotropic region. The concentration profiles of Corg, NT, Corg/NT ratios and isotopic composition (δ13C, δ15N) were determined in sediment cores collected at five sites throughout the wetland to estimate the contribution of nutrient sources to the sediments through analysis of profile shape. The results showed a recent enrichment in organic matter in the upper sediment layers at three sites (S1 to S3). Changes in the Corg/NT ratios with the sediments depth suggested that organic matter is autochthonous at the pristine sites (upper part of the wetland) characterized by an abundant coverage of vegetation. The isotopic (δ13C, δ15N) profiles (-35 to -25.8 ‰ for δ13C and 0.7 to 4.1 ‰ for δ15N) supported these conclusions and pointed to the entrance of allochthonous materials through local perturbations as a cause of changes in wetland productivity at the lower part. Analysis of isotopic composition can be used to evaluate trace productivity changes in tropical wetlands exposed to anthropogenic perturbations in this area.

In this work, two mesoporous silicas functionalized with C18 groups (SM-C18 and SBA-15-C18) have been synthesized for their evaluation as stationary phases in SPE for the extraction and preconcentration of seven steroid hormones (estrone, estradiol, estriol, ethinyl estradiol, diethylstilbestrol, testosterone, and progesterone ) from milk. The characterization of both materials by diverse techniques such as transmission electron microscopy, SEM, thermogravimetric analysis, X-ray diffraction, and adsorption-desorption isotherms showed that the mesoporous silicas had a high surface area, high pore volume, and a homogeneous distribution of the pores and that both silicas presented a similar degree of functionalization. An analytical methodology for the simultaneous separation of the seven selected steroids by HPLC-DAD was developed. Both silicas were evaluated as stationary phases in SPE for the extraction of the steroid hormones from milk. This HPLC-DAD method was applied to the analysis of all extracts obtained in the SPE experiments, showing that from the two synthesized mesoporus silicas, SBA-15-C18 silica enabled the extraction of the seven compounds with recoveries between 88 and 108% for all except for estriol, for which a recovery of 62% was obtained. The analytical characteristics of this methodology were evaluated, showing good precision and linearity (R2 > 0.994) for all analytes. The comparison of the results obtained with this silica and those obtained with commercial C18 particles and with some other commercial cartridges usually employed in the extraction of steroids showed that SBA-15-C18 silica was able to extract the seven steroids with higher recovery values.

Among the thousands of chemicals having potential to enter the environment, the NORMAN network has identified at least 700 substances categorized into 20 classes in the European surface waters. Pesticides, pharmaceuticals, disinfection by-products, wood preservation and industrial chemicals are the prominent classes. Since the impact of these substances on aquatic life and human health might be dramatic, action is urgently required at multiple levels; one of them is just related to the development of more and more sensible and selective analytical methods. This review highlights the latest advancements and trends in liquid chromatography-mass spectrometry based environmental analysis. Specific sections are dedicated to novelties in sample preparation, chromatographic separation and mass spectrometry detection of emerging pollutants. The review also offers insights on last generation chromatographic and extraction materials, technological progresses and innovative methodological approaches for target and non-target analysis. As numerous papers have been published in this field, this overview covers the most representative and original works published in the 2011-2016 period.

The potential of three capillary columns based on β-cyclodextrin (i.e., Chirasil-Dex, BGB-172, and BGB-176SE) has been studied for the simultaneous enantiomeric separation of polychlorinated biphenyls (PCBs) and methylsulfonyl metabolites of PCBs (MeSO(2)-PCBs) employing a heart-cut multidimensional gas chromatographic system (heart-cut MDGC). Among the columns studied, the BGB-176SE capillary column provided the best results, allowing the simultaneous enantioselective resolution of six MeSO(2)-PCBs and six chiral PCBs; the Chirasil-Dex column did not resolve any of the studied MeSO(2)-PCBs; and a poor resolution was obtained for three MeSO(2)-PCBs when the BGB-172 column was employed. The developed method was successfully applied to two fish oil and one cow liver samples commercially available, which showed different enantioselective pattern. PCBs 91 and 176 presented a clear enrichment of the second eluted atropisomer in codfish oil, whereas in fish oil sample, slight enrichment of the first eluted atropisomer of CB45 and the second eluted atropisomer of CB136 were observed.

The first CE method enabling the enantiomeric separation of the synthetic pyrethroid cis-bifenthrin (BF) was developed in this work. CD-MEKC was the CE mode employed for this purpose. The influence of several experimental parameters such as temperature, voltage, type and concentration of surfactant (chiral and achiral) and CD was investigated. The use of the bile salt sodium cholate at a concentration of 100 mM in the presence of 20 mM heptakis (2,3,6-tri-O-methyl)-beta-CD enabled the separation of cis-BF enantiomers in less than 10 min and with a resolution of 2.8. The analytical characteristics of the developed methodology were evaluated allowing its application to the quantitation of cis-BF in a polyvalent commercial insecticide formulation.

Pyrethroids are synthetic pesticides that originated from the modification of natural pyrethrins to improve their biological activity and stability. They are a family of chiral pesticides with a large number of stereoisomers. Enantiomers of synthetic pyretroids present different insecticidal activity, toxicity against aquatic invertebrates and persistence in the environment so the development of rapid and sensitive chiral methods for the determination of different enantiomers is necessary. Several techniques have been employed for this purpose including gas chromatography, high performance liquid chromatography or more recently capillary electrophoresis and sub or supercritical fluid chromatography. A general view on the different chiral separation methods applied to the analysis of pyrethroids and the most important information about these pesticides is provided in this review.

Summary The legumes Canavalia ensiformis and Mucuna pruriens are underexploited in tropical Mexico. Their seeds have good nutritional potential, but contain antinutritional factors. Physicochemical and antinutritional properties were determined for raw flours (RF) and protein isolates (PI) produced from these legumes. Protein content in the PI was 737 g kg–1 for C. ensiformis and 666 g kg–1 for M. pruriens. Protein isolation improved in vitro digestibility, while maintaining high lysine levels and adequate sulphur amino acids content. Antinutritional factors such as cyanogenic glucosides, cyanide precursors from hydrolysis, tannins and trypsin inhibitors were lower in the PIs than in the RFs. The reduction in canavanine levels, a structural analogue of arginine, in the C. ensiformis PI was noteworthy. These PIs thus have potential applications in the development of new food ingredients in tropical regions using processes that improve nutritional value.

An effective high performance liquid chromatography-diode array detection-tandem mass spectrometry (HPLC-DAD-MS/MS) analytical approach was developed for retinoid profiling in raw milk samples (cow, buffalo, ewe, and goat). The analytes were isolated by means of liquid-liquid extraction, including a “lipid freezing” step, with yields exceeding 66%. Since the positive atmospheric pressure chemical ionisation mass spectrometry (APCI-MS) detection is not completely selective, a reliable identification has been accomplished by fully separating the analytes on a tandem C18/C30 column system under non-aqueous reversed phase (NARP) chromatography conditions. After validation, different milk varieties obtained from pasture-fed animals were analysed, providing, for the first time, the retinoid composition of both buffalo’s and ewe’s milk. According to the literature, retinyl palmitate has been found to be the most abundant vitamin A vitamer, but retinyl oleate is the prevalent form in the caprine milk.

This paper describes a rapid method for confirming residues of thyreostats in meat-based baby foods by using liquid chromatography - dual polarity electrospray - tandem mass spectrometry (LC-ES(±)-MS/MS). Six thioureylenes, belonging to the group of thiouracil and imidazole, were selected for this work: thiouracil (TU), methylthiouracil (MTU), propylthiouracil (PTU), phenylthiouracil (PhTU), mercaptobenzimidazole (MBI) and tapazole (TAP). The amphoteric nature of these compounds allows their electrospray detection in both positive and negative ionisation. Nevertheless, MS detection is not favoured by their low molecular weights, while their chromatographic retention is also thwarted by their high polarity. A pentafluorophenyl (PFP) core-shell phase column was selected to avoid peak asymmetry or peak splitting, and a dual-polarity ionisation method was optimised to obtain a sensitivity as high as possible. The method was validated according to the Commission Decision 657/2002/EC. A simple and fast procedure based on matrix solid phase dispersion (MSPD) was optimised to extract analytes from baby foods with recoveries exceeding 82%. Limit of decision (CCα) and detection capability (CCβ) were lower than the permissible maximum concentration (10 ng g

This chapter offers a comprehensive overview of the main application fields of liquid chromatography–mass spectrometry (LC–MS) technology, highlighting practical aspects, advantages, and shortcomings. The areas covered include environmental and food applications. Emphasis is placed on potentiality and pitfalls of the different LC–MS approaches to perform both confirmation analysis and large-scale screening analysis of pesticides, drugs, and toxins using both low- and high-resolution mass spectrometry. The key role of LC–MS in the emerging omics technologies (proteomics, metabolomics, and lipidomics) will also be discussed along with “global” or “targeted” strategies to identify a huge number of proteins or metabolites. Latest advances and potential trends using LC–MS are also outlined in the several branches of the analytical chemistry. Keywords: animal foods; confirmatory methods; emerging contaminants; environmental analysis; food analysis; foodomics; food safety; lipidomics; liquid chromatography; mass spectrometry; metabolomics; multiclass analysis; multiresidue determination; plant foods; pesticides; proteomics; screening methods; surface water; toxins; veterinary drugs; wastewater

Unlike the other fat-soluble vitamins, vitamin K circulates in the human bloodstream at very low levels because of a low intake in the diet. Mammals have developed an efficient recycling system, known as vitamin K-epoxide cycle, which involve quinone, hydroquinone and epoxide forms of the vitamin. Phylloquinone (K(1)) is the main homologue, while menaquinone-4 (MK-4) is both a member of the vitamin K(2) family and metabolite of K(1) in extra-hepatic tissues. Notwithstanding the recent advances, many aspects of the complex vitamin K physiology still remain to be investigated. Therefore, there is a critical need to develop more reliable analytical methods for determining the vitamin K and its metabolites in biological fluids and tissues. Nevertheless, relatively low concentrations, unavailability of some authentic standards and occurrence of interfering lipids make this a challenging task. The method proposed in the present paper can directly and accurately estimate K(1), K(1) 2,3-epoxide (K(1)O), and MK-4 in human serum and plasma at concentrations in the ng/L-μg/L range, using labelled internal standards and a quadrupole linear ion trap instrument operated in multiple reaction monitoring (MRM) mode. High sensitivity was achieved by removing signal "endogenous suppressors" and making the composition of the non-aqueous mobile phase suitable to support the positive atmospheric pressure chemical ionization of the analytes. An excellent selectivity resulted from the combination of some factors: the MRM acquisition, the adoption of an identification point system, an extraction optimized to remove most of the lipids and a tandem-C18 column-system necessary to separate isobaric interferences from analytes. The method was validated according to the Food and Drug Administration (FDA) guidelines and its accuracy was assessed by analysing 9 samples from the Vitamin K External Quality Assessment Scheme (KEQAS). Its feasibility in evaluating vitamin K status in human serum was also tested by monitoring a group of six healthy subjects and a group of six patients under oral anticoagulant therapy (OAT). Warfarinised patients did not show deficiency of K1 but levels comparable with those of healthy people and an accumulation of K1O up to 3.760μg/L. MK-4 was not detected in either of the two groups.

This paper presents an analytical strategy for a large-scale screening of carotenoids in tomato fruits by exploiting the potentialities of the triple quadrupole-linear ion trap hybrid mass spectrometer (QqQLIT). The method involves separation on C30 reversed-phase column and identification by means of diode array detection (DAD) and atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). The authentic standards of six model compounds were used to optimize the separative conditions and to predict the chromatographic behavior of untargeted carotenoids. An information dependent acquisition (IDA) was performed with (i) enhanced-mass scan (EMS) as the survey scan, (ii) enhanced-resolution (ER) scan to obtain the exact mass of the precursor ions (16-35 ppm), and (iii) enhanced product ion (EPI) scan as dependent scan to obtain structural information. LC-DAD-multiple reaction monitoring (MRM) chromatograms were also acquired for the identification of targeted carotenoids occurring at low concentrations; for the first time, the relative abundance between the MRM transitions (ion ratio) was used as an extra tool for the MS distinction of structural isomers and the related families of geometrical isomers. The whole analytical strategy was high-throughput, because a great number of experimental data could be acquired with few analytical steps, and cost-effective, because only few standards were used; when applied to characterize some tomato varieties ('Tangerine', 'Pachino', 'Datterino', and 'Camone') and passata of 'San Marzano' tomatoes, our method succeeded in identifying up to 44 carotenoids in the 'Tangerine'" variety.

Catalysts used for heterogeneous processes are usually composed of metal nanoparticles dispersed over a high–surface-area support. In recent years, near-ambient pressure techniques have allowed catalyst characterization under operating conditions, overcoming the pressure gap effect. However, the use of model systems may not truly represent the changes that occur in real catalysts (the so-called material gap effect). Supports can play an important role in the catalytic process by providing new active sites and may strongly affect both the physical and chemical properties of metal nanoparticles. We used near-ambient pressure x-ray photoelectron spectroscopy to show that the surface rearrangement of bimetallic (rhodium-palladium) nanoparticles under working conditions for ethanol steam reforming with real catalysts is strongly influenced by the presence of a reducible ceria support.

This paper describes development and validation of a new method for the simultaneous determination of six antithyroid drugs (ATDs) in surface waters by using liquid chromatography–triple quadrupole mass spectrometry (LC–MS/MS). Target compounds include two ATD classes: thiouracil derivatives (thiouracil (TU), methyl-thiouracil (MTU), propyl-thiouracil (PTU), phenyl-thiouracil (PhTU)) and imidazole derivatives (tapazole (TAP), and mercaptobenzimidazole (MBI)). Sensitivity and selectivity of the LC-multiple reaction monitoring (MRM) analysis allowed applying a simple pre-concentration procedure and “shooting” the concentrated sample into the LC–MS/MS system without any other treatment. Recoveries were higher than 75% for all analytes. Intra-day precision and inter-day precision, calculated as relative standard deviation (RSD), were below 19 and 22%, respectively. Limits of detection (LODs) ranged from 0.05 to 0.25 μg/L; limits of quantitation (LOQs) varied between 0.15 and 0.75 μg/L. The validated method was successfully applied to the analysis of ATD residues in surface water samples collected from the Tiber River basin and three lakes of Lazio (central Italy). The analytes were quantified based on matrix-matched calibration curves with mercaptobenzimidazole-d4 (MBI-d4) as the internal standard (IS). The most widespread compound was TAP, one of the most common ATDs used in human medicine, but also TU and MBI were often detected in the analysed samples.

Plasma amyloid beta (Aβ) levels are being investigated as potential biomarkers for Alzheimer's disease. In AB128 cross-sectional study, a number of medical relevant correlates of blood Aβ40 or Aβ42 were analyzed in 140 subjects (51 Alzheimer's disease patients, 53 healthy controls and 36 individuals diagnosed with mild cognitive impairment). We determined the association between multiple variables with Aβ40 and Aβ42 levels measured in three different blood compartments called i) Aβ directly accessible (DA) in the plasma, ii) Aβ recovered from the plasma matrix (RP) after diluting the plasma sample in a formulated buffer, and iii) associated with the remaining cellular pellet (CP). We confirmed that diastolic blood pressure (DBP) is consistently correlated with blood DA Aβ40 levels (r=-0.19, P=0.032). These results were consistent in the three phenotypic groups studied. Importantly, the observation resisted covariation with age, gender or creatinine levels. Observed effect size and direction of Aβ40 levels/DBP correlation are in accordance with previous reports. Of note, DA Aβ40 and the RP Aβ40 were also strongly associated with creatinine levels (r=0.599, P<

Double transgenic mice expressing mutant amyloid precursor protein (APPswe) and mutant presenilin 1 (PS1dE9) are a model of Alzheimer-type amyloidosis and are widely used in experimental studies. In the present work, the relationships between brain and plasma amyloid-β peptide (Aβ) levels and cognitive impairments were examined in male APPswe/PS1dE9 double transgenic mice at different ages. When compared with non-transgenic littermates, APPswe/PS1dE9 mice exhibited significant learning deficits from the age of 6months (M6), which were aggravated at later stages of life (M8 and M12). Sporadic brain amyloid plaques were observed in mice as early as M3 and progressively increased in number and size up to M12. A similar increase was observed in brain insoluble Aβ levels as assessed by enzyme-linked immunosorbent assay (ELISA). In particular, the levels of brain insoluble Aβ peptides rose steeply from M4 to M6. Interestingly, this pronounced amyloid deposition was accompanied by a temporary fall in the concentration of brain soluble and membrane-bound Aβ peptides at M6 that rose again at M8 and M12. The plasma levels of Aβ40 and Aβ42 decreased with advancing age up to M8, when they stabilized at M12. This decrease in plasma Aβ levels coincided with the observed increase in insoluble brain Aβ levels. These results could be useful for developing plasma Aβ levels as possible biomarkers of the cerebral amyloidosis and provide advances in the knowledge of the Aβ peptide biochemical changes that occur in the brain of Alzheimer's disease patients.