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1.
J Phys Chem C Nanomater Interfaces ; 128(38): 16020-16031, 2024 Sep 26.
Artículo en Inglés | MEDLINE | ID: mdl-39355014

RESUMEN

We used in situ X-ray absorption spectroscopy (XAS) to investigate the composition-performance correlation of Ni-SrTiO3 photocatalysts active for water splitting. After preparation and exposure to ambient conditions, the Ni particles on SrTiO3 consist of Ni(0) and Ni(II) phases, with a 4:1 at % ratio, in a metal/oxide core/shell configuration, as confirmed by XPS and TEM-EDX. In situ XAS experiments using an aqueous slurry of the Ni-SrTiO3 photocatalyst and simultaneous continuous exposure to 365 nm light with a power density of 100 mW cm-2 and the X-rays do not reveal significant changes in oxidation state of the Ni particles. Contrarily, when the X-rays are discontinuously applied, UV excitation leads to oxidation of a significant fraction of Ni(0) to Ni(II), specifically to NiO and Ni(OH)2 phases, along with cocatalyst restructuring. Ni dissolution or oxidation to higher valence states (e.g., Ni(III)) was not observed. The UV light-induced oxidation of Ni(0) causes the hydrogen evolution rate to drop to similar rates as observed for pristine SrTiO3, suggesting that Ni(0) is the active phase for H2 generation. Our results underscore the importance of assessing the effects of (continuous) X-ray exposure to (photo)catalyst-containing aqueous slurries during in situ XAS experiments, which can significantly influence the observation of compositional and structural changes in the (photo)catalysts. We ascribe this to X-ray induced water photolysis and formation of free electrons, which in this study quench SrTiO3 photoholes and prevent Ni oxidation.

2.
Food Chem ; 463(Pt 4): 141460, 2024 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-39357309

RESUMEN

This review focuses on trace element speciation in edible mushrooms, providing information on analytical methods, available literature data, and health risk assessment. All steps of analytical procedures were presented, including extraction, separation and quantification. It compiles fragmented literature data on trace element speciation, focusing on arsenic, chromium, selenium, mercury, and antimony. Key findings include non-bioaccumulative chromium, the prevalence of Sb(V), mercury accumulation in contaminated sites, diverse arsenic and selenium speciation. Safe intake limits by agencies like USEPA indicate low risk for Cr(VI) and Sb but significant hazards from mercury and methylmercury, especially in contaminated areas: about 10 % of samples exceed safe limits for inorganic arsenic, and selenium enrichment often surpasses safety thresholds. The review underscores the need for standardized methods, speciation analyses of all toxicologically relevant species, and research on cooking impacts to improve health risk evaluations: establishing safe conditions for mushroom consumption remains a far-fetched goal.

3.
Chemosphere ; : 143581, 2024 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-39428023

RESUMEN

The analysis of metal-containing additives in plastic materials via acid digestion protocols has attracted growing interest to address potential environmental implications. However, the lack of protocol harmonization hinders data comparability within the literature. Here, six acid digestion protocols were employed to determine the metal(loid) content in plastics: these included three different acid mixtures (HNO3 combined with H2SO4, HCl or H2O2) for microwave-assisted digestion, with or without an additional room-temperature digestion step with H2O2. Each protocol was first validated for seven metal(loid)s (As, Cd, Cr, Pb, Sb, Sn and Zn) using a low-density polyethylene (LDPE) certified reference material (ERM®-EC681m). Then, validated protocols were applied on end-use materials, including conventional (i.e. LDPE) and compostable (i.e. PBAT/TPS) plastics. The combination of H2SO4 and HNO3 with a further digestion step with H2O2 was the most suitable protocol: it successfully passed validation thresholds for all metal(loid)s (recoveries in the range 98.6 - 101.0 %) and yielded the highest concentrations in end-use materials. All other protocols resulted in a less efficient digestion of the sample matrix, leading to lower recoveries and the formation of solid residues. Notably, end-use plastics showed a great variability in metal(loid) concentrations, likely due to their additive-rich composition, in contrast to the minimal content of acid-soluble additives of the reference material. This study represents an initial step towards the harmonization of acid digestion protocols and highlights new challenges in accurately analyzing end-use plastic materials, due to their complex additive composition.

4.
Nanomaterials (Basel) ; 14(19)2024 Sep 29.
Artículo en Inglés | MEDLINE | ID: mdl-39404304

RESUMEN

Anodic TiO2 nanotube arrays decorated with Ni, Cu, and NiCu alloy thin films were investigated for the first time for the photocatalytic degradation of paracetamol in water solution under UV irradiation. Metallic co-catalysts were deposited on TiO2 nanotubes using magnetron sputtering. The influence of the metal layer composition and thickness on the photocatalytic activity was systematically studied. Photocatalytic experiments showed that only Cu-rich co-catalysts provide enhanced paracetamol degradation rates, whereas Ni-modified photocatalysts exhibit no improvement compared with unmodified TiO2. The best-performing material was obtained by sputtering a 20 nm thick film of 1:1 atomic ratio NiCu alloy: this material exhibits a reaction rate more than doubled compared with pristine TiO2, enabling the complete degradation of 10 mg L-1 of paracetamol in 8 h. The superior performance of NiCu-modified systems over pure Cu-based ones is ascribed to a Ni and Cu synergistic effect. Kinetic tests using selective holes and radical scavengers unveiled, unlike prior findings in the literature, that paracetamol undergoes direct oxidation at the photocatalyst surface via valence band holes. Finally, Chemical Oxygen Demand (COD) tests and High-Resolution Mass Spectrometry (HR-MS) analysis were conducted to assess the degree of mineralization and identify intermediates. In contrast with the existing literature, we demonstrated that the mechanistic pathway involves direct oxidation by valence band holes.

5.
Org Lett ; 26(30): 6330-6334, 2024 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-39037909

RESUMEN

A synthetic protocol for the preparation of a new class of morpholino homonucleosides in enantiopure form starting from readily available 1,2-aminoalcohols or glycidol has been developed. Key intermediates of the synthetic sequence are 2-bromomethyl morpholines, diastereoselectively achieved from the corresponding alkenols by palladaelectro-catalyzed alkoxybromination of unactivated alkenes. The so obtained bromo derivatives are in turn susceptible to functionalization with nucleic bases for easy access to morpholino homonucleosides.

6.
Molecules ; 29(12)2024 Jun 16.
Artículo en Inglés | MEDLINE | ID: mdl-38930935

RESUMEN

Antimony (Sb) contamination poses significant environmental and health concerns due to its toxic nature and widespread presence, largely from anthropogenic activities. This study addresses the urgent need for an accurate speciation analysis of Sb, particularly in water sources, emphasizing its migration from polyethylene terephthalate (PET) plastic materials. Current methodologies primarily focus on total Sb content, leaving a critical knowledge gap for its speciation. Here, we present a novel analytical approach utilizing frontal chromatography coupled with inductively coupled plasma mass spectrometry (FC-ICP-MS) for the rapid speciation analysis of Sb(III) and Sb(V) in water. Systematic optimization of the FC-ICP-MS method was achieved through multivariate data analysis, resulting in a remarkably short analysis time of 150 s with a limit of detection below 1 ng kg-1. The optimized method was then applied to characterize PET leaching, revealing a marked effect of the plastic aging and manufacturing process not only on the total amount of Sb released but also on the nature of leached Sb species. This evidence demonstrates the effectiveness of the FC-ICP-MS approach in addressing such an environmental concern, benchmarking a new standard for Sb speciation analysis in consideration of its simplicity, cost effectiveness, greenness, and broad applicability in environmental and health monitoring.


Asunto(s)
Antimonio , Espectrometría de Masas , Tereftalatos Polietilenos , Antimonio/análisis , Antimonio/química , Tereftalatos Polietilenos/química , Espectrometría de Masas/métodos , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/química , Monitoreo del Ambiente/métodos
7.
J Hazard Mater ; 476: 135042, 2024 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-38944996

RESUMEN

Tires are a major source of synthetic and natural rubber particles, metals and organic compounds, in which several compounds are linked to negative environmental impact. Recent advances in material technology, coupled with focus on sustainability, have introduced a new range of tires, sold as "green, sustainable, and eco-friendly". Although these "green" tires may have lower impact on the environment on a global scale, there is no current knowledge about the chemical composition of "green" tires, and whether they are more eco-friendly when considering the release of tire wear particles or tire-associated chemicals. Here we have investigated the chemical composition of nine "green" vehicle tires, one "green" bike tire and seven "conventional" vehicle tires. No significant difference was found between "green" and "conventional" tires tested in this study. For N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), the average concentration in "green" tires were higher (16 ± 7.8 µg/mg) compared to "conventional" tires (8.7 ± 4.5 µg/mg). The relationship between metals, selected organic compounds and rubbers demonstrated large variation across brands, and lower variability between tires grouped according to their seasonal use. This study indicates that more work is needed to understand how the shift towards sustainable tires might change the chemical composition of tires.

8.
Sci Total Environ ; 946: 174325, 2024 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-38942306

RESUMEN

Soil environments across the globe, particularly in agricultural settings, have now been shown to be contaminated with microplastics. Agricultural plastics - such as mulching films - are used in close or direct contact with soils and there is growing evidence demonstrating that they represent a potential source of microplastics. There is a demand to undertake fate and effects studies to understand the behaviour and potential long-term ecological risks of this contamination. Yet, there is a lack of test materials available for this purpose. This study describes the manufacture and characterisation of five large (1-40 kg) batches of microplastic test materials derived from agricultural mulching films. Batches were produced from either polyethylene-based conventional mulching films or starch-polybutadiene adipate terephthalate blend mulching films that are certified biodegradable in soil. Challenges encountered and overcome during the micronisation process provide valuable insights into the future of microplastic test material generation from these material types. This includes difficulties in micronising virgin polyethylene film materials. All five batches were subjected to a thorough physical and chemical characterisation - both of the original virgin films and the subsequent microplastic particles generated - including a screening for the presence of chemical additives. This is a critical step to provide essential information for interpreting particle fate or effects in scientific testing. Trade-offs between obtaining preferred particle typologies and time and cost constraints are elucidated. Several recommendations emerging from the experiences gained in this study are put forward to advance the research field towards greater harmonisation and utilisation of environmentally relevant test materials.

9.
Talanta ; 270: 125612, 2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38169277

RESUMEN

Mercury is a pervasive and concerning pollutant due to its toxicity, mobility, and tendency to biomagnify in aquatic and terrestrial ecosystems. Speciation analysis is crucial to assess exposure and risks associated with mercury, as different mercury species exhibit varying properties and toxicities. This study aimed at developing a selective detection method for organic mercury species in a non-invasive biomonitoring matrix like human hair. The method is based on frontal chromatography (FC) in combination with inductively coupled plasma mass spectrometry (ICP-MS), using a low pressure, homemade, anion exchange column inserted in a standard ICP-MS introduction system, without requiring high-performance liquid chromatography (HPLC) hyphenation. In addition to the extreme simplification and cost reduction of the chromatographic equipment, the proposed protocol involves a fast, streamlined and fully integrated sample preparation process (in contrast to existing methods): the optimized procedure features a 15-min ultrasonic assisted extraction procedure and 5 min analysis time. Consequently, up to 100 samples could be analyzed daily, making the method highly productive and suitable for large-scale screening programs in public and environmental health. Moreover, the optimized procedure enables a limit of detection (LOD) of 5.5 µg/kg for a 10 mg hair microsample. All these features undeniably demonstrate a significant advancement in routine biomonitoring practices. To provide additional evidence, the method was applied to forty-nine human hair samples from individuals with varying dietary habits successfully finding a clear correlation between methylmercury levels (ranging from 0.02 to 3.2 mg/kg) in hair and fish consumption, in line with previous literature data.


Asunto(s)
Mercurio , Compuestos de Metilmercurio , Animales , Humanos , Monitoreo Biológico , Ecosistema , Mercurio/análisis , Compuestos de Metilmercurio/análisis , Cromatografía Líquida de Alta Presión/métodos , Cabello/química
10.
Sci Total Environ ; 893: 164807, 2023 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-37315607

RESUMEN

Plastic particles can impact the environmental fate and bioavailability of essential inorganic micronutrients and non-essential (toxic) metals. The sorption of metals to environmental plastic has been demonstrated to be facilitated by plastic ageing, a phenomenon encompassing an array of physical, chemical, and biological processes. This study deploys a factorial experiment to untangle the role of different ageing processes in determining the sorption of metals. Plastics made of three different polymer types were aged both through abiotic (ultraviolet irradiation, UV) and biotic (through the incubation with a multispecies algal inoculum forming a biofilm) processes under controlled laboratory conditions. Pristine and aged plastic samples were characterized for their physiochemical properties through Fourier-transformed infrared spectroscopy, scanning electron microscopy and water contact angle measurements. Their sorption affinity toward aluminum (Al) and copper (Cu) in aqueous solutions was then assessed as a response variable. All ageing processes (alone or combined) influenced plastic surface properties resulting in reduced hydrophobicity, changes in surface functional groups (i.e., increase of oxygen containing functional groups after UV ageing and the appearance of marked bands as amides and polysaccharides after biofouling), as well as in nanomorphology. The sorption of Al and Cu was instead statistically dependent (p < 0.01) on the degree of biofouling covering the specimens. Biofouled plastic displayed in fact substantial affinity for metal sorption causing the depletion of up to tenfold Cu and Al compared to pristine polymers, regardless of the polymer type and presence or absence of other ageing treatments. These results confirm the hypothesis that the accumulation of metals on plastic is substantially driven by the biofilm present on environmental plastics. These findings also highlight the importance of investigating the implications of environmental plastic for metal and inorganic nutrients availability in environments impacted by this pollution.


Asunto(s)
Incrustaciones Biológicas , Contaminantes Químicos del Agua , Plásticos/química , Contaminantes Químicos del Agua/análisis , Metales , Cobre , Agua , Aluminio
11.
J Hazard Mater ; 452: 131330, 2023 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-37004438

RESUMEN

The interaction between environmental plastic and trace elements is an issue of concern. Understanding their interaction mechanisms is key to evaluate the potential threats for the environment. To this regard, consolidating confidence in extraction protocols can help in understanding the amount of different species present on plastic surface, as well as the potential mobility of trace elements present inside the plastic matrix (e.g., additives). Here we tested the efficacy of different reagents to mimic the elemental phases bonded to meso- and microplastic in the environment, in relation to the grade of ageing and the polymer composition. Results showed that a relatively high portion of trace elements is bonded in a weak phase and that other phases abundant in other matrices (e.g., oxides and bonded to organic matter) are only present to a limited degree in the plastic samples. The comparison of different sample types highlighted the important role of plastic ageing in governing interactions with trace elements, while the polymer composition has a limited influence on this process. Finally, the future steps toward a tailored extraction scheme for environmental plastic are proposed.

12.
Molecules ; 28(6)2023 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-36985816

RESUMEN

The goal of accurately quantifying trace elements in ultrapure silicon carbide (SiC) with a purity target of 5N (99.999% purity) was addressed. The unsuitability of microwave-assisted acid digestion followed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis was proved to depend mainly on the contamination induced by memory effects of PTFE microwave vessels and by the purity levels of acids, even if highly pure ones were used in a clean environment. A new analytical protocol for the direct analysis of the solid material by laser ablation coupled with ICP-MS (LA-ICP-MS) was then exploited. Different samples were studied; the best results were obtained by embedding SiC (powders or grains) in epoxy resin. This technique has the great advantage of avoiding any source of external contamination, as grinding, pressing and sintering pretreatments are totally unnecessary. Two different laser wavelengths (266 and 193 nm) were tested, and best results were obtained with the 266 nm laser. The optimized protocol allows the determination of elements down to the sub-mg/kg level with a good accuracy level.

13.
Environ Sci Pollut Res Int ; 30(3): 6298-6312, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-35994148

RESUMEN

Pollution by plastic and microplastic impacts the environment globally. Knowledge on the ageing mechanisms of plastics in natural settings is needed to understand their environmental fate and their reactivity in the ecosystems. Accordingly, the study of ageing processes is gaining focus in the context of the environmental sciences. However, laboratory-based experimental research has typically assessed individual ageing processes, limiting environmental applicability. In this study, we propose a multi-tiered approach to study the environmental ageing of polyethylene plastic fragments focusing on the combined assessment of physical and biological processes in sequence. The ageing protocol included ultraviolet irradiation in air and in a range of water solutions, followed by a biofouling test. Changes in surface characteristics were assessed by Fourier transform infrared spectroscopy, scanning electron microscopy, and water contact angle. UV radiation both in air and water caused a significant increase in the density of oxidized groups (i.e., hydroxyl and carbonyl) on the plastic surface, whereby water solution chemistry influenced the process both by modulating surface oxidation and morphology. Biofouling, too, was a strong determinant of surface alterations, regardless of the prior irradiation treatments. All biofouled samples present (i) specific infrared bands of new surface functional groups (e.g., amides and polysaccharides), (ii) a further increase in hydroxyl and carbonyl groups, (iii) the diffuse presence of algal biofilm on the plastic surface, and (iv) a significant decrease in surface hydrophobicity. This suggests that biological-driven alterations are not affected by the level of physicochemical ageing and may represent, in real settings, the main driver of alteration of both weathered and pristine plastics. This work highlights the potentially pivotal role of biofouling as the main process of plastic ageing, providing useful technical insights for future experimental works. These results also confirm that a multi-tiered laboratory approach permits a realistic simulation of plastic environmental ageing in controlled conditions.


Asunto(s)
Plásticos , Contaminantes Químicos del Agua , Polietileno/análisis , Ecosistema , Contaminantes Químicos del Agua/análisis , Agua , Monitoreo del Ambiente
14.
Artículo en Inglés | MEDLINE | ID: mdl-36231411

RESUMEN

The goals of this work are the evaluation of the performances of official methods in the challenging determination of Cr(VI) in Cr(III)-rich particulate matter, and the development of a novel and robust analytical protocol for this issue. A liquid chromatography inductively coupled plasma mass spectrometry apparatus (LC-ICP-MS), together with an isotope-enriched spike addition technique, was used to allow the study of Cr(III)/Cr(VI) interconversions during the extraction step. An original separation strategy based on Cr(OH)3 head-column stacking was developed to tolerate high concentrations of Cr(III) (up to 10 mg/kg, with a Cr(VI) limit of detection of 0.51 µg/kg) without the need of any sample pretreatment. After observing, the official extraction protocols always yield false positive values in the challenging situation of particulate matter of leather industries (where huge amounts of Cr(III) are present), a new extraction strategy was developed. The novel procedure involves a 48-h extraction at room temperature using a pH-8 phosphate buffer, which demonstrated that no Cr(III)/Cr(VI) interconversions occur during this phase. To get rid of any possible interference caused by co-extracted substances, the measurement of the redox potential, together with the addition of a Fe(II)/Fe(III) redox buffer was performed to fix chromium speciation during the overall analytical protocol.


Asunto(s)
Cromo , Compuestos Férricos , Cromo/análisis , Polvo/análisis , Compuestos Ferrosos , Isótopos , Espectrometría de Masas/métodos , Material Particulado/análisis , Fosfatos
15.
Methods Protoc ; 5(2)2022 Apr 03.
Artículo en Inglés | MEDLINE | ID: mdl-35448695

RESUMEN

The complete dissolution of silicate-containing materials, often necessary for elemental determination, is generally performed by microwave-assisted digestion involving the forced use of hydrofluoric acid (HF). Although highly efficient in dissolving silicates, this acid exhibits many detrimental effects (e.g., formation of precipitates, corrosiveness to glassware) that make its removal after digestion essential. The displacement of HF is normally achieved by evaporation in open-vessel systems: atmospheric contamination or loss of analytes can occur when fuming-off HF owing to the non-ultraclean conditions necessarily adopted for safety reasons. This aspect strongly hinders determination at the ultra-trace level. To overcome this issue, we propose a clean and safe microwave-assisted procedure to induce the evaporative migration of HF inside a sealed "vessel-inside-vessel" system: up to 99.9% of HF can be removed by performing two additional microwave cycles after sample dissolution. HF migrates from the digestion solution to a scavenger (ultrapure H2O) via a simple physical mechanism, and then, it can be safely dismissed/recycled. The procedure was validated by a soil reference material (NIST 2710), and no external or cross-contamination was observed for the 27 trace elements studied. The results demonstrate the suitability of this protocol for ultra-trace analysis when the utilization of HF is mandatory.

16.
Anal Chim Acta ; 1206: 339553, 2022 May 08.
Artículo en Inglés | MEDLINE | ID: mdl-35473882

RESUMEN

A fast and cost-effective procedure based on Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) for the selective determination of methylmercury (MeHg) is proposed and validated for fish tissue analysis. Selectivity for MeHg is achieved by simply inserting a strong anion exchange resin to block inorganic mercury as negatively charged chloride species, leaving MeHg unretained. The procedure features a 15 min extraction time followed by a 100 s analysis time achieving a limit of detection of 1.6 µg kg-1 on solid samples. The effect of the solution composition and inorganic mercury concentration were extensively studied to fully assess the selectivity of the procedure: Hg(II):MeHg ratios up to 50 are tolerated and cause systematic errors lower than 15%. The entire procedure was successfully validated by standard reference material from the marine food web, namely fish muscle and liver plus zooplankton. The method was finally applied to the detection of MeHg in the marine trophic web of Djibouti (Gulf of Aden): a trophic magnification factor of 13.5 proved the high risk associated with the biomagnification of methylmercury.


Asunto(s)
Mercurio , Compuestos de Metilmercurio , Animales , Peces , Cadena Alimentaria , Mercurio/análisis , Compuestos de Metilmercurio/análisis , Análisis Espectral
17.
Water Res ; 204: 117637, 2021 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-34536685

RESUMEN

Plastic and microplastic pollution is an environmental and societal concern. The interaction of plastic with organic chemicals in the environment has attracted scientific interest. New evidences have highlighted an unexpectedly high affinity of environmental plastics also for metal ions. The degree and typology of plastic ageing (including from mechanical, UV and biological degradations) appear as a pivotal factor determining such an interaction. These earlier evidences recently opened a new research avenue in the plastic pollution area. This review is the first to organize and critically discuss knowledge developed so far. Results from field and laboratory studies of metal accumulation on plastic are presented and the environmental factors most likely to control such an interaction are discussed. On the light of this knowledge, a generalist conceptual model useful for building hypotheses on the mechanisms at stake and directing future studies was elaborated and presented here. Furthermore, all available data on the thermodynamics of the plastic-metal interaction obtained from laboratory experiments are inventoried and discussed here, highlighting methodological and technical challenges that can potentially affect cross-comparability of data and their relevance for environmental settings. Finally, insights and recommendations on experimental approaches and analytical techniques that can help overtaking current limitations and knowledge gaps are proposed.


Asunto(s)
Oligoelementos , Contaminantes Químicos del Agua , Monitoreo del Ambiente , Microplásticos , Plásticos , Agua , Contaminantes Químicos del Agua/análisis
18.
J Hazard Mater ; 412: 125280, 2021 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-33550126

RESUMEN

An analytical method derived from the coupling of frontal chromatography (FC) with Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) is proposed for the fast determination of Cr(VI) ultra-traces. The insertion of a short, homemade column filled with a strong cationic exchange resin in the flow-path of a commercial ICP-MS allows on-line trapping of cationic Cr(III) and elution of anionic Cr(VI). As a result, only the Cr(VI) front reaches the detector. This separation mechanism enables the highly selective quantification of Cr(VI) ultra-traces (LOD = 0.026 µg/kg - defined as 3 s of 10 replicated measurements of a 0.050 µg/kg solution) over a wide linearity range (tested up to 1024 µg/kg), even in the presence of Cr(III) concentration as high as 50 mg/kg. Key advantages of the proposed method are the extremely short analysis time (one minute), together with the simplicity and cost-effectiveness of the modifications applied over a commercial ICP-MS instrumental configuration. No time- or chemical-consuming pretreatments are needed: it is only necessary to acidify the sample prior Cr(VI) determination, as normally performed for common ICP-MS analysis. The applicability of the method was demonstrated over mineral water samples and toy migration solutions.

19.
Biosensors (Basel) ; 10(9)2020 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-32916940

RESUMEN

The use of insoluble bismuth salts, typically BiPO4, is known to be a viable alternative to classical Bi3+ ion electrochemical reduction for the preparation of bismuth film electrodes (BiFE) on screen-printed electrodes. The freshly prepared electrodes are indefinitely stable, and the active bismuth film is simply formed by in situ reduction. Two aspects are still to be investigated, namely the bismuth distribution on the working electrode and the possible residual presence of the counteranion, namely phosphate. High-vacuum techniques such as electron microscopy or spectroscopy, which are commonly employed for this purpose, cannot be safely used: the bismuth surface is well-known to reconstruct and recrystallize under the electron beam in vacuum. Here, we demonstrate the suitability and the effectiveness of laser ablation ICP-MS (LA-ICP-MS, a technique that vaporizes and analyzes the surface material under flowing helium at atmospheric pressure) for the characterization of BiFE. Fast and stable measurements of bismuth and phosphorous distribution are achieved with the advantage of a minimum alteration of the sample surface, avoiding possible interferences. This investigation evidenced how, upon reductive activation, the bismuth film is distributed with a radial symmetry and the phosphate counteranion is completely absent on the working electrode surface.


Asunto(s)
Bismuto/química , Electrodos , Terapia por Láser , Espectrofotometría Atómica , Electroquímica , Rayos Láser , Análisis Espectral
20.
Anal Sci ; 36(7): 889-892, 2020 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-32009020

RESUMEN

In this paper, we proposed a high-throughput microwave digestion system based on multi-batch reactors (three quartz test tubes inside commercial PTFE vessels). This original configuration was validated by ICP-MS analysis of several elements in biological certified reference materials (fish tissues and plankton). The proposed system was proved to be free from contamination showing very low LODs. The improved hardware configuration is therefore highly beneficial for the detection of trace elements in microsamples from the marine food web.


Asunto(s)
Ensayos Analíticos de Alto Rendimiento , Microondas , Oligoelementos/análisis , Animales , Peces , Espectrometría de Masas , Plancton , Oligoelementos/metabolismo
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