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- 2021 (15) (entfernen)
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Zellen, als Grundeinheit für Organismen, bilden einen wesentlichen Eckpfeiler für das Leben. Die Untersuchung von einzelnen Zellen liefert wertvolle Einblicke in fundamentale Prozesse des Lebens. So können Anomalien auf der Zelleebene Indikatoren für Krankheiten sein und durch eine Analyse früh erkannt werden. Weiterhin kann durch ein tiefgreifendes Verständnis von Vorgängen in Zellen auch gezielt Forschung zu z.B. neuen Medikamenten betrieben werden. Damit können die Wirksamkeit erhöht und die Nebenwirkungen reduziert werden.
Rationale: (Eco-)toxicological effects are mostly derived empirically and are notcorrelated with metal uptake. Furthermore, if the metal content is determined,mostly bulk analysis of the whole organism population is conducted; thus, biologicalvariability is completely disregarded, and this may lead to misleading results. Toovercome this issue, we compared two different solid sampling techniques for theanalysis of single organisms.Methods: In this study, complementary electrothermal vaporization/inductivelycoupled plasma mass spectrometry (ETV/ICP-MS) , laser ablation/inductivelycoupled plasma mass spectrometry (LA/ICP-MS)-based methods for the analysisof individual organisms were developed and the results obtained were comparedwith the concentrations obtained after digestion and measured using ICP-MS.For this purpose, a common (eco-)toxicological test organism, the mud shrimpCorophium volutator, was selected. As proof-of-concept application, these organismswere incubated with environmentally relevant metals from galvanic anodes, whichare often used for protection against metal corrosion in, for example, offshorewind farms.Results: The bulk analysis revealed that large quantities of the incubated elementswere detectable. Using the ETV/ICP-MS method, we could identify a highbiovariability within the population of organisms tested. Using the LA/ICP-MSmethod, it could be determined that the large quantities of the elements detectedwere due to adsorption of the metals and not due to uptake, which correlates wellwith the absence of (eco-)toxicological effects.Conclusions: The results obtained imply the efficiency of complementary methods toexplain the absence or presence of (eco-)toxicological effects. In particular, methodsthat allow for single-organism analysis or provide even a spatial resolution supportthe interpretation of ecotoxicological findings.
Molekülmassenspektrometrie entwickelt sich weg von klassischer Target- hin zu Nontarget-Analytik. Elementmassenspektrometrie liefert hohe Ortsauflösung beim Element-Imaging und analysiert einzelne Zellen. Aufgrund der Fortschritte bei den Geräten für Timeof-Flight-Massenspektrometrie mit induktiv gekoppeltem Plasma (ICPToF-MS) lässt sich das gesamte Periodensystem der Elemente in kurzen transienten Signalen quasi-simultan massenspektrometrisch erfassen.
Materials in contact with the environment release e.g., metal-ions, elemental species and/or (nano-)particles. Once these species and/or particles are released, they are ingested by organisms and cells and thus, might have a negative impact on the environment. Thus, identification as well as quantification of potentially harmful substances is of utmost importance and highly needed to assess ecotoxicological impact of (emerging) pollutants.
The oral presentation provides an overview on the power of elemental analytical techniques, in particular ICP-MS as well as HR-CS-GFMAS in environmental research. Current research topics from Division 1.1 @ BAM - Inorganic trace analysis will be highlighted:
i) Elemental Speciation & Isotope analysis - new tools:
Among elemental species separation and quantification, one of the main challenges in environmental elemental speciation analysis is the distinction between anthropogenic and natural elemental species. The on-line combination of elemental speciation and isotope analysis combines “the best from both worlds” - species specific isotopic information becomes available.
As an application example the analysis of current anti-fouling agents via CE/MCICP-MS will be highlighted.
ii) HR-CS-GFMAS for PFC analysis:
Per- and polyfluorinated compounds (PFC) are emerging contaminants in particular in soil and surface water samples. Due to the large number of compounds (>4700), target analytical methods are not sufficient and sum parameter methods for organically bound fluorine are highly needed.
High resolution-continuum source-graphite furnace molecular absorption spectroscopy (HR-CS-GFMAS) based methods for organically bound fluorine analysis will be presented. Application examples (soil and surface water) will be highlighted.
iii) Single cell-ICP-ToF-MS - ecotox. assessment:
Single cell and single organism analysis for e.g. ecotoxicological/medicinal assessment are hot topics in the research field of ICP-MS. In particular ICP-ToF-MS is a powerful, emerging techniques in terms of single cell/particle analysis.
Automated single cell/diatom-ICP-ToF-MS as a potential tool in ecotoxicological testing will be presented.
In many scientific fields, isotopic analysis can offer valuable information, e.g., for tracing the origin of food products, environmental contaminants, forensic and archaeological samples (provenance determination), for age determination of minerals (geochronological dating) or for elucidating chemical processes. Up to date, typically bulk analysis is aimed at measuring the isotopic composition of the entire elemental content of the sample. However, the analyte element is usually present under the form of different species. Thus, separating species of interest from one another and from matrix components prior to isotope ratio measurements can provide species-specific isotopic information, which could be used for tracing the origin of environmental pollutants and elucidation of (environmental) speciation. Using on-line hyphenations of separation techniques with multicollector-ICP-MS (MC-ICP-MS) can save time and effort and enables the analysis of different species during a single measurement.
In this work, we developed an on-line hyphenation of CE with multicollector-ICP-MS (CE/MC-ICP-MS) for isotopic analysis of sulfur species using a multiple-injection approach for instrumental mass bias correction by standard-sample bracketing. With this method, the isotopic composition of sulfur in sulfate originating from river water could be analyzed without sample preparation. The results were compared to data from off-line analysis of the same samples to ensure accuracy. The precision of the results of the on-line measurements was promising regarding the differentiation of the river systems by the isotopic signature of river water sulfate. The great potential of this method is based on the versatility of the applied separation technique, not only in the environmental field but also for, e.g., biomolecules, as sulfur is the only covalently bound constituent of proteins that can be analyzed by MC-ICP-MS.
Materials in contact with the environment release e.g., metal-ions, elemental species and/or (nano-)particles. Once these species and/or particles are released, they are ingested by organisms and cells and thus, might have a negative impact on the environment. Thus, identification as well as quantification of potentially harmful substances is of utmost importance and highly needed to assess ecotoxicological impact of (emerging) pollutants.
The oral presentation provides an overview on the power of elemental analytical techniques, in particular: ICP-MS as well as HR-CS-GFMAS in environmental research. Current research topics will be highlighted:
i) Elemental Speciation analysis of anti-fouling agents via CE/MC-ICP-MS;
ii) Per- and polyfluorinated compounds in surface waters via high resolution-continuum source-graphite furnace molecular absorption spectroscopy (HR-CS-GFMAS);
iii) Single cell and single organism analysis via sc-ICP-ToF-MS and ETV/ICP-MS for ecotoxicological assessment.
Zinc phosphate, an important pigment in phosphate conversion coatings, forms protective films on rubbing surfaces.
We have simulated the underlying reactions under shear by ball-milling zinc phosphate and monitored the reaction of hopeite (Zn3(PO4)2·4H2O) and the retarded recrystallization of the amorphous reaction product by powder X-ray diffraction (PXRD) and quantitative infrared (IR) spectroscopy. Abrasion of stainless steel was simulated by addition of pure 57Fe. The results provide insight into the chemistry of phosphate conversion coatings or during battery cycling of metal phosphates and give theoretical guidance for the preparation of amorphous phosphates. Thermal analysis revealed that the release of structural water is a key step during the reaction of hopeite under shear to ball-milled amorphous zinc phosphate. The back-reaction and associated recrystallization kinetics of amorphous zinc phosphate show a classical Langmuir behavior. Fe impurities inhibit the recrystallization of ball-milled amorphous zinc phosphate strongly. 57Fe Mössbauer spectroscopy and PXRD revealed that Fe is oxidized to Fe2+ and Fe3+ during ball-milling and incorporated locally at the tetrahedral and octahedral sites of the structure. Ball-milled amorphous zinc phosphate is metastable as γ-Zn3−xFex(PO4)2. EPR studies showed the incorporation of Fe3+ to be coupled with the formation of Zn2+ vacancies. The Fe3+ defect sites bind water because of their higher Pearson hardness (compared to Fe2+ and Zn2+), thereby reducing water mobility and inhibiting further reactions like the recrystallization to hopeite. Our findings reveal the amorphization mechanism of Zn3(PO4)2·4H2O in stainless steel ball mills at the atomic scale and highlight how the reactivity of amorphous products is affected by impurities associated with the processing method.
A general method to carry out the fluorination of metal oxides with poly(tetrafluoroethylene) (PTFE, Teflon) waste by spark plasma sintering (SPS) on a minute scale with Teflon is reported. The potential of this new approach is highlighted by the following results. i) The tantalum oxyfluorides Ta3O7F and TaO2F are obtained from plastic scrap without using toxic or caustic chemicals for fluorination. ii) Short reaction times (minutes rather than days) reduce the process time the energy costs by almost three orders of magnitude. iii) The oxyfluorides Ta3O7F and TaO2F are produced in gram amounts of nanoparticles. Their synthesis can be upscaled to the kg range with industrial sintering equipment. iv) SPS processing changes the catalytic properties: while conventionally prepared Ta3O7F and TaO2F show little catalytic activity, SPS-prepared Ta3O7F and TaO2F exhibit high activity for photocatalytic oxygen evolution, reaching photoconversion efficiencies up to 24.7% and applied bias to photoconversion values of 0.86%. This study shows that the materials properties are dictated by the processing which poses new challenges to understand and predict the underlying factors.
Solid state reactions are slow because the diffusion of atoms or ions through the reactant, intermediate and crystalline product phases is the rate-limiting step. This requires days or even weeks of high temperature treatment, and consumption of large amounts of energy. We employed spark-plasma sintering, an engineering technique that is used for high-speed consolidation of powders with a pulsed Electric current passing through the sample to carry out the fluorination of niobium oxide in minute intervals. The approach saves time and large amounts of waste energy. Moreover, it allows the preparation of fluorinated niobium oxides on a gram scale using poly (tetrafluoroethylene) (®Teflon) scrap and without toxic chemicals.
The synthesis can be upscaled easily to the kg range with appropriate sintering equipment. Finally, NbO2F and Nb3O7F prepared by spark plasma sintering show significant photoelectrocatalytic (PEC) oxygen evolution from water in terms of photocurrent density and incident photon-to-current Efficiency (% IPCE), whereas NbO2F and Nb3O7F prepared by conventional high temperature chemistry show little to no PEC response. Our study is a proof of concept for the quick, clean and energy saving production of valuable photocatalysts from plastic waste.
Per- und polyfluorierte Alkylverbindungen (PFAS) sind sehr persistent und reichern sich in der Umwelt und im menschlichen Organismus in immer höheren Konzentrationen an. PFAS stellen deshalb eine große Gefährdung für Mensch und Umwelt dar. Eingesetzt werden sie u. a. als wasser- und fettabweisende Beschichtung in z. B. der Papier- und Textilindustrie und gelangen so während Produktion, Gebrauch und Entsorgung u. a. in den Wasserkreislauf. PFAS konnten sogar in der arktischen Umwelt in relevanten Konzentrationen detektiert werden und zählen somit zu den „emerging pollutants“. Ein prominenter Vertreter der PFAS stellt Perfluoroctansulfonsäure (PFOS) dar - die jedoch bereits im Anhang des Stockholmer Abkommen gelistet wurde und deren Einsatz somit stark eingeschränkt bzw. verboten ist. Im Hinblick auf die Vielzahl von Verbindungen werden neue analytische Methoden benötigt, die eine PFAS-Belastungssituation möglichst umfassend und nachweisstark widerspiegeln, um zukünftig mögliche Grenzwerte ableiten zu können.
A recently introduced inductively coupled plasma-time-of-flight-mass spectrometer (ICP-ToF-MS) shows enhanced sensitivity compared to previous developments and superior isotope ratio precision compared to other ToF and commonly used single-collector ICP-MS instruments. Following this fact, an improvement for isotope dilution ICP-MS using the new instrumentation has been reported. This study aimed at investigating whether this improvement also meets the requirements of species-specific isotope dilution using GC/ICP-MS, where short transient signals are recorded. The results of the analysis of monomethylmercury (MMHg) of a sediment reference material show that isotope ratio precision of ICP-MS instruments equipped with quadrupole, sector-field, and time-of-flight mass analyzers is similar within a broad range of peak signal-to-noise ratio when analyzing one isotopic system. The procedural limit of quantification (LOQ) for MMHg, expressed as mass fraction of Hg being present as MMHg, w(Hg)MMHg, was similar as well for all investigated instruments and ranged between 0.003 and 0.016 μg/kg. Due to the simultaneous detection capability, the ICP-ToF-MS might, however, be more favorable when several isotopic systems are analyzed within one measurement. In a case study, the GC/ICP-ToF-MS coupling was applied for analysis of MMHg in sediments of Finow Canal, a historic German canal heavily polluted with mercury. Mass fractions between 0.180 and 41 μg/kg (w(Hg)MMHg) for MMHg, and 0.056 and 126 mg/kg (w(Hg)total) for total mercury were found in sediment samples taken from the canal upstream and downstream of a former chemical plant.