4 Material und Umwelt
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Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (46) (entfernen)
Eingeladener Vortrag
- nein (27)
In addition to previously reported results on the simulated aging of polystyrene samples (PS) containing 1 wt. % hexabromocyclododecane (HBCD), we present the first results of our investigations of polypropylene (PP)-samples containing 0.1 wt. % BDE-209. All studied polymer samples were exposed to a defined weathering schedule in a climate chamber in accordance to regulation EN ISO 4892-3:2006.For the determination of BDE-209 in the collected rain water samples derived from the used climate chamber, the samples were prepared in accordance with a validated protocol. Before the analyses, each sample was spiked with 2 µL of isotopically labeled BDE-209 (13C10-BDE-209) to serve as internal standard (ISTD) in the performed stable isotope dilution analysis. Subsequently the samples were extracted with isooctane, the obtained aliquots of the extracts were concentrated to 200 µL and 2 µL of the resulting solution were injected to the GC/MS for quantification.
Additionally, the total bromine contents are monitored for the aged and untreated samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as well as X-ray fluorescence analysis (XRF) as non-destructive and rapid method. Furthermore, results from surface analysis using environmental scanning electron microscopy (ESEM) for morphological characterization of the aged and untreated samples were presented and discussed. In general, the resulting data from the accelerated aging will be compared to those from the natural weathering experiments (“atmospheric exposure”, in soil).
The atmospheric exposure was performed by placing the samples on a weathering rack, which is aligned in SW direction (in a 45° angle to the horizon). The weathering data were regularly recorded by Deutscher Wetterdienst at this site. The surfaces of the test specimens (aged and stored references) were analyzed by ESEM as well as by LA-ICP-MS and by XRF. The surface of PS and PP specimens aged outdoors present the aging under real conditions and allow the comparison to the accelerated aged specimens by means of the weathering chamber. This way, we explore the efficiency of the accelerated aging procedure, which provides the advantage of well-defined and reproducible conditions compared to natural weathering, as a tool for testing different plastic materials.
Additionally “in soil” experiments were conducted in-door in a well characterized testing soil. The soil (boulder-clay, sand with 12 % loam, particle size in total 0.2-4 mm) is filled in a free-draining concrete basin inside of an air-conditioned room. In this manner, TOC, water capacity and humidity are recorded parameters. To assure a washing out process from the samples by the raining water, the target water content is calculated to 8%. The actual humidity is measured by a tensiometer, assuring the duration of the raining period. The water content is additionally monitored by weight of the basin, capturing water from raining periods. The correct humidity is a fundamental parameter for biological activity. Samples of PS resp. PP were of dimension 10x1cm and 5 specimens were placed up to the half in the soil per basin. Microbial activity of the soil, monitored by the reference polyurethane, sets HBCD resp. BDE-209 of the samples free and will be leached from the samples by raining water. Thereafter these will be captured by passive samplers placed in a distinct distance to the samples in the soil. The “in soil” experiments are complementary to the weathering experiments due to the biological activity in the soil. These experiments simulate the fate of the brominated flame retardants in the biosphere.
Emission testing of volatile organic compounds (VOC) from materials and products is commonly based on emission test chamber measurements. To ensure the comparability of results from different testing laboratories their measurement performance must be verified. For this purpose, Bundesanstalt für Materialforschung und -prüfung (BAM) organizes an international proficiency test every two years using well-characterised test materials (one sealant, one furniture board and four times a lacquer) with defined VOC emissions. The materials fulfilled the requirements of homogeneity, reproducibility, and stability. Altogether, 41 VOCs were included of which 37 gave test chamber air concentrations between 10 and 98 µg/m³. This is the typical concentration range to be expected and to be quantified when performing chamber tests. Four compounds had higher concentrations between 250 and 1105 µg/m³. The relative standard deviations (RSD) of BAM proficiency tests since 2008 are compared and the improvement of the comparability of the emission chamber testing is shown by the decrease of the mean RSD down to 23% in 2021. In contrast, the first large European interlaboratory comparison in 1999 showed a mean RSD of 51%.
Im Beitrag wurden Ergebnisse von Elutionsuntersuchungen mit PFC kontaminierten Bodenmaterialien vorgestellt. Zum einen waren das Untersuchungen zur Eignung von Säulenversuchen für diese Schadstoffgruppe und zum anderen vergleichende Schüttel- und Säulenversuche für zwei verschiedene Böden mit unterschiedlichen PFC-Kontaminationsquellen.
Tour de table - BAM
(2021)
BAM is currently building up a platform of novel nanoRMs relying on iron oxide nanoparticles of different shape, size and surface chemistry. Iron oxide was chosen as a core material because of its relevance to the material and life sciences.
As a first candidate of this series, we present cubic iron oxide nanoparticles with a nominal edge length of 8 nm. These particles were synthesized by thermal decomposition of iron oleate in high boiling organic solvents adapting well-known literature procedures. After dilution to a concentration suitable for electron microscopy (TEM and SEM) as well as for small-angle X-ray scattering (SAXS) measurements, the candidate nanoRM was bottled and assessed for homogeneity and stability by both methods following the guidelines of ISO 17034 and ISO Guide 35.
The particle sizes obtained by both STEM-in-SEM and TEM are in excellent agreement with a minimum Feret of 8.3 nm ± 0.7 nm. The aspect ratio (AR) of the iron oxide cubes were extracted from the images as the ratio of minimum Feret to Feret resulting in an AR of 1.18 for TEM to 1.25 for SEM. Alternatively, a rectangular bounding box was fitted originating from the minimum Feret and the longest distance through the particle in perpendicular direction. This led to AR values of 1.05 for TEM and 1.12 for SEM, respectively. The results confirm the almost ideal cubic shape.
Gegenstand des Projekts ist die Prüfung der Umweltbeständigkeit und -verträglichkeit von Materialien und Produkten hinsichtlich der Emission von potenziellen Schadstoffen in die Umwelt. Hierzu werden chemisch-physikalische Einflüsse (Bewitterung) und mikrobielle Beanspruchungen an Modellmaterialien evaluiert. So werden die Freisetzungsraten von Schadstoffen in Abhängigkeit der Beanspruchung beschrieben. Als Modellmaterialien kommen die Polymere Polycarbonat, Polytetrafluorethylen, Polystyrol und Polypropylen zum Einsatz. Synergistische Effekte der Bewitterungsparameter und der mikrobiologischen Beanspruchung sollen dabei ebenso betrachtet werden, wie die gezielte Alterung. Auch findet eine Beschreibung des Verhaltens der ausgetragenen Schadstoffe in den Umweltkompartimenten Boden oder Wasser statt. Hier sind mit Hilfe der zu entwickelnden Screening- und non-Target-Analyseverfahren die Transformation und der Metabolismus durch Mikroorganismen zu beschreiben. Aus den Ergebnissen sollen Korrelationen zwischen den künstlichen Alterungsverfahren und realen Szenarien abgeleitet werden, die es gestatten, Schnellprüfverfahren zu etablieren, die die Simulation der realen Beanspruchungen im Zeitraffermodell anwendbar machen. Somit sollen standardisierbare Schnellbeanspruchungs-verfahren erarbeitet werden, die als Prüfeinrichtungen etabliert werden und von externen Auftraggebern zur Prüfung der Umweltbeständigkeit und -verträglichkeit von neuen Materialien genutzt werden können. Die Umweltwirkungen (chemisch-physikalisch und mikrobiologisch) sollen so definiert eingesetzt werden, dass eine reproduzierbare Prüfung möglich wird. Aus diesen Verfahren und Methoden sollen Normen abgeleitet werden, die eine standardisierte Materialprüfung ermöglichen.
Gegenstand dieser Arbeit ist die Untersuchung eines bestehenden pyrometallurgischen Prozesses zur Rückgewinnung von Tantal und Niob aus metallurgischen Reststoffen mit vorwiegend niedriger Wertstoffkonzentration.
Zur näheren Erforschung der im vorliegenden Stoffsystem ablaufenden Reduktionsprozesse wurden in einem Elektrolichtbogenofen Schmelzversuche im Pilotmaßstab durchgeführt. Als Reduktionsmittel diente Koks, welcher mithilfe einer Argon-gespülten Eisenlanze in die flüssige mineralische Schmelze eingebracht wurde. Während der Reduktionsbehandlung werden Refraktärmetalle wie Tantal und Niob in ihre Carbide überführt und anschließend in der erschmolzenen eisenbasierten Metallphase am Boden des Reaktors angereichert. Neben Tantal und Niob gelangt auch ein Teil des im Einsatzmaterial enthaltenen Titans als unerwünschtes Begleitelement in die Metallphase.
Sein Großteil verbleibt jedoch als Oxid in der Schlacke und wird dort hauptsächlich im Mineral Perowskit (CaTiO3) gebunden. Die erstarrten Schlackeproben wurden mit verschiedenen Methoden wie Röntgenfluoreszensanalyse, Röntgenbeugung und Rasterelektronenmikroskopie mit gekoppelter energiedispersiver Röntgenanalyse untersucht, um die Bildung tantalhaltiger Mineralphasen zu verschiedenen Stadien des Reduktionsprozesses zu verfolgen.
Die hier gewonnenen Erkenntnisse zeigen, dass weniger die durch das Einblasen von Koks verursachte Reduktionsreaktion, sondern das Absinken der tantalreichen Eisentröpfchen in der flüssigen mineralischen Schmelze, gefolgt von ihrer Anreicherung in die Metallphase, für die Kinetik ausschlaggebend ist.
Die gemeinsame Forschungsstrategie der Bundesoberbehörden zur Nanotechnologie wurde 2016 veröffentlicht. Die darin enthaltenen Aufgaben wurden von den Bundesoberbehörden vielfältig bearbeitet. Diese Präsentation gibt einen Überblick über die Projekte, die von der BAM bis 2019 bearbeitet wurden/werden und sich in den Rahmen der Forschungsstrategie einordnen.
Round robin tests of odour and VOC emissions from building products – What have we learned so far?
(2023)
Emission testing of volatile organic compounds (VOC) and odour from materials and products is commonly based on emission test chamber measurements. These measurements are often the basis of mandatory or voluntary labelling procedures. To ensure the comparability of results from different testing laboratories their performance must be verified. For this purpose, round robin tests (RRTs) are conducted. Bundesanstalt für Materialforschung und - prüfung (BAM) offers such a RRT every two years using well characterised test materials with defined VOC emissions. In addition to the VOC quantification, the evaluation of odour is also implemented in the round robin tests. At the beginning, only perceived intensity (PI) was tested but over the years also the acceptance evaluation was considered. In principle, the results of PI and acceptance evaluation are comparable. The advantage of PI is the lower number of panel members necessary for one evaluation.
The biogenesis of iron–sulfur (Fe/S) proteins entails the synthesis and trafficking of Fe/S clusters, followed by their insertion into target apoproteins. In eukaryotes, the multiple steps of biogenesis are accomplished by complex protein machineries in both mitochondria and cytosol. The underlying biochemical pathways have been elucidated over the past decades, yet the mechanisms of cytosolic [2Fe-2S] protein assembly have remained ill-defined. Similarly, the precise site of glutathione (GSH) requirement in cytosolic and nuclear Fe/S protein biogenesis is unclear, as is the molecular role of the GSH-dependent cytosolic monothiol glutaredoxins (cGrxs). Here, we investigated these questions in human and yeast cells by various in vivo approaches. [2Fe-2S] cluster assembly of cytosolic target apoproteins required the mitochondrial ISC machinery, the mitochondrial transporter Atm1/ABCB7 and GSH, yet occurred independently of both the CIA system and cGrxs. This mechanism was strikingly different from the ISC-, Atm1/ABCB7-, GSH-, and CIA-dependent assembly of cytosolic–nuclear [4Fe-4S] proteins. One notable exception to this cytosolic [2Fe-2S] protein maturation pathway defined here was yeast Apd1 which used the CIA system via binding to the CIA targeting complex through its C-terminal tryptophan. cGrxs, although attributed as [2Fe-2S] cluster chaperones or trafficking proteins, were not essential in vivo for delivering [2Fe-2S] clusters to either CIA components or target apoproteins. Finally, the most critical GSH requirement was assigned to Atm1-dependent export, i.e. a step before GSH-dependent cGrxs function. Our findings extend the general model of eukaryotic Fe/S protein biogenesis by adding the molecular requirements for cytosolic [2Fe-2S] protein maturation.
The project ProMoAM is presented. The goal of the project is to evaluate which NDT techniques or combination of techniques is suited for in-situ quality assurance in additive manufacturing of metals. To this end, also 3d-data fusion and visualization techniques are applied. Additional ex-situ NDT-techniques are used as references for defect detection and quantification. Feasability studies for NDT-techniques that are presently not applicable for in-situ use are performed as well.
The presentation gives a brief overview of the whole project and the different involved NDT-techniques.
Volatile organic compounds (VOCs) emitted by furniture and
building materials can cause health issues. For an
improvement of indoor air quality low emitting materials
should be used. Quality assurance and –control (QA/QC)
measures require an emission reference material (ERM) with a
predictable emission rate of VOCs. The idea is to use porous
materials as ERM, which store the VOCs inside their pores and
emit them constantly.
Neuartige Materialien, die bekannte (Werk-)Stoffe mit neuen Funktionalitäten ausstatten, spielen eine zunehmend wichtige Rolle im Bereich der Materialforschung und -prüfung. Das Spektrum neuartiger Materialien reicht von der gezielten Oberflächenfunktionalisierung und -strukturierung makroskopischer Materialien, dünnen Beschichtungen bis hin zu mikro- und nanoskaligen Kompositmaterialien und funktionalen Materialien an der Schnittstelle zur Biologie, Biotechnologie, nachhaltige Energiespeicherung und Sensorik. Dabei bieten neuartige Materialien die Chance, Werkstoffe und Produkte mit erweiterter oder verbesserter Funktionalität zu erhalten und Sicherheit bereits im Designprozess zu berücksichtigen. Durch dieses breite Anwendungsspektrum und die Herausforderungen, die solche Materialien für die Sicherheit in Chemie und Technik mit sich bringen, sind diese in allen Themenfeldern der BAM repräsentiert (Material, Analytical Sciences, Energie, Infrastruktur und Umwelt).
Die Aufgaben der BAM erstrecken sich dabei von der Herstellung von Referenzmaterialien für Industrie, Forschung und Regulation, über die Erstellung von standardisierten Referenzverfahren für nachhaltige Messungen im Umwelt- und Lebenswissenschaftsbereich bis hin zur Bereitstellung von belastbaren und zitierbaren Referenzdaten. Durch die genaue Charakterisierung neuartiger Materialien können potentiell problematische Substanzen identifiziert und deren Risiken besser abgeschätzt werden. In diesem Beitrag werden einige aktuelle Beispiele aus diesen Bereichen vorgestellt.
Per- and polyfluoroalkyl substances (PFAS) are chemicals which were developed to improve humanity’s quality of life. Due to their high chemical stability and resistance to degradation by heat or acids, PFAS were used in a variety of consumer products. The continuous use of PFAS in household products and the discharge of PFAS from industrial plants into the sewer system resulted in the contamination of effluents and sewage sludge from wastewater treatment plants (WWTPs) (Roesch et al. 2022). Since sewage sludge is often used as fertilizer, its application on agricultural soils has been observed as a significant entry path for PFAS into the environment, specifically in our food chain. In Germany the sewage sludge/biosolid application on agricultural land was banned with the amendment of the German Sewage Sludge Ordinance and by 2029 sewage sludge application will be totally prohibited. However, phosphorus (P) from sewage sludge should still be recycled in WWTPs of cities with a population larger than 50,000 residents. To produce high-quality P-fertilizers for a circular economy, PFAS and other pollutants (e.g. pesticides and pharmaceuticals) must be separated from sewage sludge. Due to the strong diversity of industrial PFAS usage it is not clear if a safe application of novel recycled P-fertilizers from WWTPs can be guaranteed. Therefore, we analyzed various sewage sludges and wastewater-based fertilizers. Sewage sludge (SL) samples from various WWTPs in Germany and Switzerland, six sewage sludge ashes (SSA) from Germany, six thermally treated SL and SSA samples with different additives (temperatures: 700-1050 °C), two pyrolyzed SL samples (temperature: 400 °C) and two struvite samples from Germany and Canada were analyzed. The goal was to quantify PFAS in sewage sludges and wastewater-based P-fertilizers with the sum parameter extractable organic fluorine (EOF) by combustion ion chromatography (CIC). The results were compared with data from classical LC-MS/MS target analysis as well as selected samples by HR-MS suspect screening. The EOF values of the SLs mainly range between 154 and 538 µg/kg except for one SL which showed an elevated EOF value of 7209 µg/kg due to high organofluorine contamination. For the SSA samples the EOF values were lower and values between LOQ (approx. 60 µg/kg) and 121 µg/kg could be detected. For the pyrolyzed SLs no EOF values above the LOQ were detected. Moreover, the two wastewater-based struvite fertilizers contain 96 and 112 µg/kg EOF, respectively. In contrast to the EOF values, the sum of PFAS target values were relatively low for all SLs. Additional applied PFAS HR-MS suspect screening aimed to tentatively identify PFAS that could contribute to the hitherto unknown part of the EOF value. The majority of the detected fluorinated compounds are legacy PFAS such as short- and long-chain perfluorocarboxylic acids (PFCA), perfluorosulfonic acids (PFSA), polyfluoroalkyl phosphate esters (PAPs) and perfluorophosphonic acids (PFPA). Moreover, fluorinated pesticides, pharmaceutical as well as aromatic compounds were also identified, which are all included in the EOF parameter. Our research revealed that the current PFAS limit of 100 µg/kg for the sum of PFOS + PFOA in the German Fertilizer Ordinance is no longer up to date. Since the number of known PFAS already exceeds 10,000, the ordinance limit should be updated accordingly. Recent regulations and restrictions on using long-chain PFAS (≥C8) have resulted in a significant shift in the industry towards (ultra-)short-chain alternatives, and other, partly unknown, emerging PFAS. Ultimately, also fluorinated pesticides and pharmaceuticals, which end up as ultrashort PFAS in the WWTPs, have to be considered as possible pollutants in fertilizers from wastewater, too.
Abstract: Since it is unknown for many applications, which PFASs are used and how they enter the environment, target analysis-based methods reach their limits. The two most frequently used sum parameters are the adsorbable organically bound fluorine (AOF) and the extractable organically bound fluorine (EOF). Both can be quantified using either combustion ion chromatography (CIC) or high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). Here we provide an insight on the advantageous and disadvantageous of both sum parameters and both detection methods. Our study is based on the analysis of surface water samples. Next to total fluorine (TF) analysis, AOF and EOF were determined as well as CIC and HR-CS-GFMAS are compared and results are comparatively discussed. Fluorine mass balancing revealed that, the AOF/TF proportion was higher than the EOF/TF proportion. The AOF made up 0.14–0.81% of TF and the EOF 0.04–0.28% of TF. Although, organically bound fluorine represents only a small portion of TF, PFASs are of worldwide concern, because of their extreme persistence and their bioaccumulation potential. The EOF-HR-CS-GFMAS method turned out to be more precise and sensitive than the AOF-CIC method and is a promising tool for future monitoring studies/routine analysis of PFASs in the environment.
A brief perspective of BAM on nanocarriers is presented including examples with special emphasis on the characterization of such materials and underlying challenges. In this respect, also ongoing activities at BAM on different types of core/shell nanomaterials and related systems are briefly summarized.
Monodisperse iron oxide nanoparticles as reference material candidate for particle size measurements
(2020)
In order to utilize and rationally design materials at the nanoscale the reliable characterization of their physico-chemical properties is highly important, especially with respect to the assessment of their environmental or biological impact. Furthermore, the European Commission’s REACH Regulations require the registration of nanomaterials traded in quantities of at least 1 ton. Powders or dispersions where 50% (number distribution) of the constituent particles have sizes ≤ 100 nm in at least one dimension are defined as nanomaterials. This creates a need for industrial manufacturers and research or analytical service facilities to reliably characterize potential nanomaterials. Currently, BAM is developing reference nanoparticles, which shall expand the scarce list of worldwide available nano reference materials certified for particle size distribution and will also target other key parameters like shape, structure, porosity or functional properties. In this respect, materials like iron oxide or titanium dioxide are considered as candidates to complement the already available silica, Au, Ag, and polystyrene reference nanoparticles.
The thermal decomposition of iron oleate precursors in high boiling organic solvents can provide large quantities of iron oxide nanoparticles that can be varied in size and shape.[1, 2] The presence of oleic acid or other hydrophobic ligands as capping agents ensures stable dispersion in nonpolar solvents. Such monodisperse, spherical particles were synthesized at BAM and pre-characterized by electron microscopy (TEM, SEM including the transmission mode STEM-in-SEM) and dynamic light scattering comparing cumulants analysis and frequency power spectrum.
1. REACH regulations and nanosafety concerns create a strong need for nano reference materials with diverse properties.
2. Iron oxide nanoparticles are under development as new candidate reference material at BAM.
3. Narrow particle size distribution confirmed by light scattering and electron microscopy.
Fused filament fabrication (FFF) on desktop 3D printers is a material extrusion-based technique often used by educational institutions, small enterprises and private households. Polymeric filaments are melted and extruded through a heated nozzle to form a 3D object in layers. The extrusion temperature is therefore a key parameter for a successful print job, but also one of the main driving factors for the emission of harmful air pollutants, namely ultrafine particles and volatile organic gases, which are formed by thermal stress on the polymeric feedstock. The awareness of potential health risks has increased the number of emission studies in the past years. However, the multiplicity of study designs makes an objective comparison of emission data challenging because printer hardware factors such as the actual extruder temperature (TE) and also feedstockspecific emissions are not considered. We assume that across the market of commercial low- and mid-price FFF printers substantial deviations between actual and set extruder temperatures exist, which have a strong effect on the emissions and hence may bias the findings of exposure studies. In our last publication, we presented a standardized feedstock-specific emission test method and showed that for each investigated feedstock an increase in actual extruder temperature was accompanied by an increase in particle emissions (Tang and Seeger, 2022). Therefore, any systematic discrepancy between set and actual extruder temperature matters. In this study, we used a thermocouple and an infrared camera to measure the actual extruder temperatures at different heights. We found significant under- and overestimation of the actual extruder temperatures by the respective set temperatures in three commercial printers. This caused a broad variation of the measured total numbers of emitted particles (TP), even when the same feedstock was operated. For the determination of TP, we followed the DE-UZ 219 test guideline. In a second round we repeated the tests with all printers adjusted to exactly the same extruder temperatures, i.e., to TE=230°C for ABS and TE=210°C for PLA. All measurements were conducted in a 1 m³ emission test chamber. Particle emissions in the size range between 4 nm and 20 μm were detected. Printing on three different printer models without temperature adjustment resulted for each of the investigated feedstocks in a variation in TP of around two orders of magnitude. After temperature adjustment, this was substantially reduced to approx. one order of magnitude and hence minimizes the bias of printer hardware on the emissions. Our findings suggest that adjustment of the extruder temperature should be mandatory in emission testing standards. It also poses a more accurate benchmark and provides more reliable emission data for evaluation of indoor air quality or for health risk assessments. In addition, a proper temperature setting is in the interest of the user. Some commercial FFF printers may have a higher actual extruder temperature than displayed and unintended overheating may not only impair the print quality but may cause unnecessarily increased exposure to particle emissions.
In industrialised countries more than 80% of the time is spent indoors. Products, such as building materials and furniture, emit volatile organic compounds (VOCs), which are therefore ubiquitous in indoor air. Different VOC combinations may, under certain environmental and occupational conditions, result in reported sensory irritation and health complaints. A healthy indoor environment can be achieved by controlling the sources and by eliminating or limiting the release of harmful substances into the air. One way is to use materials proven to be low emitting. Meanwhile, a worldwide network of professional commercial and non-commercial laboratories performing emission tests for the evaluation of products for interior use has been established. Therefore, comparability and metrological traceability of test results must be ensured. A laboratory’s proficiency can be proven by internal and external validation measures that both include the application of suitable reference materials. The emission test chamber procedure according to EN 16516 comprises several steps from sample preparation to sampling of test chamber air and chromatographic analysis. Quality assurance and quality control (QA/QC) must therefore be ensured. Currently, there is a lack of suitable reference products containing components relevant for the health-related evaluation of building products.
The EU-funded EMPIR project 20NRM04 MetrIAQ (Metrology for the determination of emissions of dangerous substances from building materials into indoor air) aims to develop 1) gaseous primary reference materials (gPRM), which are used for the certification of gaseous (certified) reference materials (gCRM) and 2) emission reference materials (ERM).
Most commercial gas standards of indoor-relevant compounds are not certified due to the lack of primary reference materials to which the project aims to contribute. The gPRM under development is a gas-phase standard containing trace levels of VOCs in nitrogen or air from the check standard according to EN 16516 (n-hexane, methyl isobutyl ketone, toluene, butyl acetate, cyclohexanone, o-xylene, phenol, 1,3,5-trimethylbenzene) with a target uncertainty of 5 %. The gPRM can be sampled into sorbent tubes to obtain transfer standards in the form of gCRM.
The well characterised ERM represents a sample of a test specimen, e.g. building material, that is loaded into the emission test chamber for a period of several days and is used to evaluate the whole emission test chamber procedure. It shall have a reproducible and temporally constant compound release of less than 10 % variability over 14 days. Different approaches for retarded VOC release, such as the encapsulation of pure compounds and the impregnation of porous materials, are being tested to reach this aim. Furthermore, the design of the ERM is accompanied by the development of a numerical model for the prediction of the emissions for each of the target VOCs. The current progress of the work on both materials will be presented.
Microbiologically influenced corrosion (MIC) is a highly unpredictable process dictated by the environment, microorganisms, and the respective electron source. Interaction pathways between cells and the metal surface remain unclear. The development of this novel single cell-inductively coupled plasma-time of flight-mass spectrometry analytical method and a MIC-specific staining procedure facilitate the investigation of steel-MIC interactions. With this it is possible to analyze the multi-elemental fingerprint of individual cells. The detection method revealed elemental selectivity for the corrosive methanogenic archaeal strain Methanobacterium-affiliated IM1. The interface between material and environmental analysis thus receives special attention, e.g., when considering MIC on solid steel. Hence, the possible uptake of individual elements from different steel samples is investigated. Results showed the cells responded at a single-cell level to the different types of supplemented elements and displayed the abilities to interact with chromium, vanadium, titanium, cobalt, and molybdenum from solid metal surfaces. The information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts, thus combining modern methods of analytical sciences with materials research.
Gegenstand der vorzustellenden Arbeiten ist die Prüfung der Umwelt-beständigkeit und -verträglichkeit von Materialien und Produkten hinsichtlich der Emission von potenziellen Schadstoffen in die Umwelt. Hierzu werden chemisch-physikalische Einflüsse (Bewitterung) und mikrobielle Beanspruchungen an Modellmaterialien evaluiert. So werden die Freisetzungsraten von Schadstoffen in Abhängigkeit der Beanspruchung beschrieben. Als Modellmaterialien kommen die Polymere Polystyrol (PS) und Polypropylen (PP) zum Einsatz. Synergistische Effekte der Bewitterungsparameter und der mikrobiologischen Beanspruchung sollen dabei ebenso betrachtet werden, wie die gezielte Alterung. Auch findet eine Beschreibung des Verhaltens der ausgetragenen Schadstoffe (polybromierte Flammschutzmittel) in den Umweltkompartimenten Boden oder Wasser statt. Hier sind mit Hilfe der zu entwickelnden Screening- und non-Target-Analyseverfahren die Transformation und der Metabolismus durch Mikroorganismen zu beschreiben. Aus den Ergebnissen sollen Korrelationen zwischen den künstlichen Alterungsverfahren und realen Szenarien abgeleitet werden.
Nonporous corundum powder, known as an abrasive material in the industry, was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices. The materials based on corundum were characterized by TEM, ESEM, BET, DLS, and zeta potential measurements. The strong Al-O-P bonds between the corundum surface and amino phosphonic acids are used to introduce functional groups for further conjugations. The common cross-linker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter is oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). This work shows that oxidized polyglycerol can be used as an alternative to glutaraldehyde. With polyglycerol, more of the model protein bovine serum albumin (BSA) could be attached to the surface under the same conditions, and lower nonspecific binding (NSB) was observed. As a proof of concept, IgG was extracted with protein A from crude human plasma. The purity of the product was examined by SDS-PAGE. A binding capacity of 1.8 mg IgG per g of corundum powder was achieved. The advantages of corundum are the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, and flexible application.
Up to now, different analytical methods for single cell analysis exist focusing on key features such as size, shape, morphology and elemental composition. The combination of the latest ICP-MS techniques - ICP-ToF-MS - together with the latest developments in the field of sample delivery - micro droplet generator (MDG) – will allow a Deep insight into the composition and size of cells.
Microbiologically influenced corrosion (MIC) is an oxidation of metals affected by the presence or activity (or both) of microorganisms e.g. Shewanella Putrefaciens in biofilms on the surface of the corroding material. As this can happen for example in the soil on iron pipes of water pipes, in oil tanks or on steel sheet piling, there is great interest in MIC research, not only from various industrial sectors, but also from the environmental aspect.
Environmental sustainability and –stability of Materials concerning the Migration of pollutants
(2018)
MaUS is an acronym for ”Material und Umweltsimulationen“. Plastics are in the focus of environmental politics due to their long-term behaviour and therefore to their persistence. Not only that they appear as visible contaminants in the sea and on the beach, but their unknown behaviour concerning their additives as well as the related transformation products are anxious. Therefore, we wish to establish a certified reference method to provide a method for testing plastics.
Aim of this project is the development of fast motion standard reference methods for testing plastics regarding to their environmental compatibility. To establish these testing methods, we use polystyrene (PS) and polypropylene (PP) with environmental relevant brominated flame retardants, known for their persistent bioaccumulative and toxic (PBT) properties. In case of PS the material contains 1 wt% of 1,2,5,6,9,10-hexabromocyclododecan (HBCD) and in case of PP 0.1 wt% bromodiphenylether (BDE-209), which is known as a substance of very high concern (SVHC). Furthermore, we use polycarbonate (PC), which is still used as material in baby flasks and releases Bisphenol A (BPA), an estrogenic active substance.
As an additional material PTFE is used for its importance as a source for two ubiquitous environmental substances (PFOS and PFOA), whose toxicological effects are still incompletely known.
The focus in this current work is set on the transfer of potential pollutants out of applied materials mentioned above into environmental compartments like water or soil. Here an accelerated aging concept should be developed to shortened time consuming natural processes. For these resulting simulations we use a programmable weathering chamber with dry and wet periods and with high and low temperatures. These programmes run for several weeks and according to a defined sampling schedule we take water samples, run a clean-up procedure by SPE (Molecular imprinted polymers (MiPs) resp. polymer-based cartridges (Waters Oasis HLB)) and analyse them by HPLC-UV resp. LC-MS/MS. Of most interest in case of flame retardants are photocatalytic transformation products. Therefore, we conduct a non-target-screening resp. a suspected target-screening by LC-MS/MS and HRMS.
Environmental sustainability and –stability of materials concerning the migration of pollutants
(2019)
In addition to previously reported results on the accelerated weathering of polystyrene samples (PS) containing 1 wt. % hexabromocyclododecane (HBCD), we present the first results of our investigations of polypropylene samples (PP) containing 0.1 wt. % BDE-209. All studied polymer samples were exposed to a defined weathering schedule in a climate chamber in accordance to regulation EN ISO 4892-3:2006. For the determination of BDE-209 in the collected raining water the samples were prepared in accordance to a validated protocol. Before the analyses each sample was spiked with isotopically labeled BDE-209. Subsequently the samples were extracted with isooctane. The obtained extracts were concentrated, and the resulting solutions were analyzed by GC/MS. Additionally, the total bromine content was monitored for the weathered and untreated samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and X-ray fluorescence analysis (XRF) as a non-destructive and rapid method. In general, the resulting data from the accelerated weathering will be compared to those from the natural weathering experiments. Here, the surfaces of the test pieces were analyzed by LA-ICP-MS and XRF as well. Moreover, soil bed tests were conducted in a well characterized model soil. This soil (boulder-clay, sand with 12 % loam, particle size in total 0.2-4 mm) is filled in a free-draining basin inside of an air-conditioned cellar. In this manner, TOC, water capacity and humidity are recorded parameters. To induce a leaching process from the samples by the raining water, the target water content is calculated to 8%. The actual humidity is measured by a tensiometer, assuring the duration of the raining period. A defined humidity is a fundamental parameter for a biological activity in the soil. The test polymers were placed up to the half in the soil. Microbial activity of the soil is monitored by a reference polymer (polyurethane) and should induce the release of HBCD and BDE-209 out of the test materials. These released analytes will be captured by passive samplers (silicone tubes) placed in a distinct distance to the polymer samples in the soil. The soil bed experiments are complementary to the weathering experiments due to the biological activity in the soil.
In industrialised countries more than 80% of the time is spent indoors. Products, such as building materials and furniture, emit volatile organic compounds (VOCs), which are therefore ubiquitous in indoor air. VOC in combination may, under certain environmental and occupational conditions, result in reported sensory irritation and health complaints. Emission concentrations can become further elevated in new or refurbished buildings where the rate of air exchange with fresh ambient air may be limited due to improved energy saving aspects. A healthy indoor environment can be achieved by controlling the sources and by eliminating or limiting the release of harmful substances into the air. One way is to use (building) materials proved to be low emitting. Meanwhile, a worldwide network of professional commercial and non-commercial laboratories performing emission tests for the evaluation of products for interior use has been established. Therefore, comparability of test results must be ensured. A laboratory’s proficiency can be proven by internal and external validation measures that both include the application of suitable emission reference materials (ERM). For the emission test chamber procedure according to EN 16516, no artificial ERM is commercially available. The EU-funded EMPIR project MetrIAQ aims to fill this gap by developing new and improved ERMs. The goal is to obtain a material with a reproducible and temporally constant compound release (less than 10 % variability over 14 days). Two approaches were tested: the impregnation of porous materials with VOC, and the encapsulation of VOC in polymer microcapsules. Impregnation is performed with help of an autoclave and supercritical CO2. The encapsulation is done by interfacial polymerisation on VOC droplets. For both approaches, synthesis and/or material parameters were varied to obtain an optimal ERM. Findings about the optimisation of ERM generation, as well as performance of the best emission reference materials, will be presented.
Microbial contamination of fuels by fungi or bacteria poses risks such as corrosion and fuel system fouling, which can lead to critical problems in refineries and distribution systems and has a significant economic impact at every stage of the process. Many factors have been cited as being responsible for microbial growth, like the presence of water in the storage tanks. In fact, only 1 % water in a storage system is sufficient for the growth of microorganisms like bacteria or yeasts, as well as for the development of fungal biomass at the oil/water interface.
This work presents a rapid test for the accurate determination of genomic DNA from aqueous fuel extracts. The detection is based on the use of polystyrene-mesoporous silica core-shell particles onto which modified fluorescent molecular beacons are covalently grafted. These beacons contain in the hairpin loop a target sequence highly conserved in all bacteria, corresponding to a fragment of the 16S ribosomal RNA subunit. The designed single-stranded molecular beacon contained fluorescein as an internal indicator and a quencher in its proximity when not hybridized. Upon hybridization in presence of the target sequence, the indicator and the quencher are spatially separated, resulting in fluorescence enhancement. To perform the assay the developed particles were deposited on different glass fibre strips to obtain a portable and sensitive rapid test. The assays showed that the presence of genomic DNA extracts from bacteria down to 50–70 μg L–1 induced a fluorescence response. The optical read-out was adapted for on-site monitoring by fitting a 3D-printed case to a conventional smartphone, taking advantages of the sensitivity of the CMOS detector. Such embedded assembly enabled the detection of genomic DNA in aqueous extracts down to the mg L–1 range and represents an interesting step toward on-site monitoring of fuel contamination.
Fluorometric sensing is a versatile approach for trace analysis outside of the laboratory, requiring suitable sensor materials and their integration into sensing devices. The versatility of fluorophores as probes, especially in terms of the possibility to tailor their optical as well as their recognition properties by synthetic modifications in a wide range, renders them as superior active component for the preparation of optical sensing devices. Recent works at BAM in this field include, for example, the detection of nerve gas agents, illustrating impressively the aforementioned benefits of fluorophores in optical sensing applications.
In the interdisciplinary project presented here, we target hazardous gases such as ammonia, benzene, and hydrogen sulfide, next to others, which pose a major threat to human health and environmental safety and for which the availability of a sensitive and reliable detection method is highly desirable. The dyes presented follow a “turn-on” fluorescence schematic, which allows for the selective and sensitive detection of the respective gaseous analyte. The immobilization of the probe in polymeric matrices is then the next step toward the fabrication of a prototype device for molecular sensing. Further steps in the project include the assembly of instruments for test-atmosphere generation, the referencing of the sensor system, development and implementation of an optical setup, and the testing of the prototype device under laboratory conditions and in the field.
In this presentation, we give an overview over the recent developments on this topic in our groups. Highlights are hydrogen sulfide sensitive, BODIPY based transition metal complexes, which allow for a sensitive as well as selective detection of the toxic gas. In addition, we present a novel class of highly substituted BODIPY derivatives – pocket-BODIPYs – which are of a synthetically high versatility and can readily be modified to create pockets in the periphery of the molecule of defined geometries. This is illustrated on the successful encapsulation of benzene by a pocket-BODIPY derivative, confirmed by X-ray crystallographic analysis as well as by further spectroscopic and analytical methods.
Volatile organic compounds (VOCs) emitted by furniture and building materials can cause health issues. For an improvement of indoor air quality low emitting materials should be used. Quality assurance and –control (QA/QC) measures require an emission reference material (ERM) with a predictable emission rate of VOCs. The idea is to use porous materials as ERM, which store the VOCs inside their pores and emit them constantly.
The latest ICP-MS technology - ICP-ToF (time of flight)-MS – enables the analysis of the multi-element fingerprint of individual cells. The interface between material and environmental analysis thus receives special attention, e.g., when considering corrosion processes. Microbiologically influenced corrosion (MIC) is a highly unpredictable phenomenon due to the influence of the environment, microbial communities involved and the respective electron source. However, the interaction pathway between cells and the metal surface remains unclear. The development of the MIC-specific ICP-ToF-MS analytical method presented here at the single cell level, in combination with the investigation of steel-MIC interactions, contributes significantly to progress in instrumental MIC analysis and will enable clarification of the processes taking place. For this, a MIC-specific staining procedure was developed. It allows the analysis of archaea at a single cell level and provides information about the interaction of the cells with the staining agent which is extremely scarce compared to other well characterized organisms. Additionally, the single cell ICP-ToF-MS is used for the analysis of archaea involved in MIC of steel. Hence, the possible uptake of individual elements from different steel samples is investigated - the information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts, thus combining modern methods of analytical sciences with materials.
With the latest ICP-MS technology - ICP-ToF (time of flight)-MS - it is possible to analyze the multi-element fingerprint of individual cells. The interface between material and environmental analysis thus receives special attention, e.g. when considering corrosion processes. Microbiologically influenced corrosion (MIC) is highly unpredictable due to the diversity of microbial communities involved. The development of the MIC-specific ICP-ToF-MS analytical method presented here at the single cell level, in combination with the investigation of steel-MIC interactions, contributes significantly to progress in instrumental MIC analysis and will enable clarification of the processes taking place.
The supplied document shows the basis of a four minutes lightning talk.
ICP-ToF (Flugzeitanalysator, engl. time of flight)-MS ermöglicht den Multielement Fingerabdruck einzelner Zellen (single cell) zu analysieren. Die single cell-ICP-ToF-MS kommt bei dem vorgestellten Poster bei der Analyse von Archaeen, die an mikrobiell beeinflusster Korrosion (engl. microbiologically influenced corrosion, MIC) von Stahl eine Rolle spielen, zum Einsatz. Mittels sc-ICP-ToF-MS wird die mögliche Aufnahme von einzelnen Elementen aus dem jeweiligen Stahl untersucht – die erhaltenen Informationen fließen zukünftig in die Aufklärung zugrunde liegender Mechanismen sowie Entwicklung möglicher Materialschutzkonzepte ein. Die Arbeiten Verknüpfen moderne Methoden der Analytical Sciences mit Materialien.
Deciphering microbiological influenced corrosion processes on steel with single cell-ICP-ToF-MS
(2022)
Microbiologically influenced corrosion (MIC) is a highly unpredictable process dictated by the environment, microorganisms, and the respective electron source. Interaction pathways between cells and the metal surface remain unclear. The development of this novel single cell-inductively coupled plasma-time of flight-mass spectrometry analytical method and a MIC-specific staining procedure facilitate the investigation of steel-MIC interactions. With this it is possible to analyze the multi-elemental fingerprint of individual cells. The detection method revealed elemental selectivity for the corrosive methanogenic archaeal strain Methanobacterium-affiliated IM1. The interface between material and environmental analysis thus receives special attention, e.g., when considering MIC on solid steel. Hence, the possible uptake of individual elements from different steel samples is investigated. Results showed the cells responded at a single-cell level to the different types of supplemented elements and displayed the abilities to interact with chromium, vanadium, titanium, cobalt, and molybdenum from solid metal surfaces. The information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts, thus combining modern methods of analytical sciences with materials research.
References.
ICP-ToF (time of flight) MS enables the analysis of the multi-element fingerprint of single cells. The single cell ICP-ToF-MS is used in the presented poster for the analysis of archaea involved in microbiologically influenced corrosion (MIC) of steel. By means of sc-ICP-ToF-MS, the possible uptake of individual elements from the respective steel is investigated - the information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts. The work combines modern methods of analytical sciences with materials.
Angesichts der zunehmenden Digitalisierung und dem Einsatz datenintensiver Methodiken in der Wissenschaft stehen Forschende vor der Herausforderung, stetig wachsende Datenmengen nachvollziehbar zu dokumentieren, langfristig zu speichern und für Dritte nachnutzbar zu machen. Um diesen Anforderungen gerecht zu werden, bietet sich die Nutzung von Software-Lösungen an, welche Forschungsdatenmanagement mit der digitalen Dokumentation von Laborinventar und Experimenten in elektronischen Laborbüchern (engl. electronic lab notebooks (ELN)) verknüpfen.
Nonporous corundum powder was functionalized covalently with protein binders to isolate and enrich specific proteins from complex matrices.The common crosslinker glutaraldehyde was compared with a hyperbranched polyglycerol (PG) of around 10 kDa. The latter was oxidized with periodate to generate aldehyde groups that can covalently react with the amines of the surface and the amino groups from the protein via a reductive amination process. The amount of bound protein was quantified via aromatic amino acid analysis (AAAA). As a proof of concept, IgG was extracted with protein A from crude human plasma. The advantages of corundum include the very low price, extremely high physical and chemical stability, pressure resistance, favorable binding kinetics, convenient handling, and flexible application.
Per- and polyfluoroalkyl substances (PFAS) are a large group of organofluorine surfactants used in the formulations of thousands of consumer goods. The continuous use of PFAS in household products and the discharge of PFAS from industrial plants into the sewer system have been resulted in contaminated effluents and sewage sludge from wastewater treatment plants (WWTPs) which became an important pathway for PFAS into the environment. Because sewage sludge is often used as fertilizer its application on agricultural soils has been observed as significant input path for PFAS into our food chain. To produce high-quality phosphorus fertilizers for a circular economy from sewage sludge, PFAS and other pollutants (e.g. pesticides and pharmaceuticals) must be separated from sewage sludge. Normally, PFAS are analyzed using PFAS protocols typically with time-consuming extraction steps and LC-MS/MS target quantification. However, for screening of PFAS contaminations in wastewater-based fertilizers also the DGT technique can be used for the PFAS extraction. Afterwards, combustion ion chromatography (CIC) can be applied to analyze the “total” amount of PFAS on the DGT binding layer. The DGT method was less sensitive and only comparable to the extractable organic fluorine (EOF) method values of the fertilizers in samples with >150 µg/kg, because of different diffusion properties for various PFAS, but also kinetic exchange limitations. However, the DGT approach has the advantage that almost no sample preparation is necessary. Moreover, the PFAS adsorption on the DGT binding layer was investigated via surface sensitive spectroscopical methods, such as Fourier-transform infrared (FT-IR) and fluorine K-edge X-ray absorption near-edge structure (XANES) spectroscopy.
Zearalenone (ZEN) and its sulfate and glucoside conjugates have been detected in (a broad variety of) food and feed commodities1. Both conjugated derivatives are formed as part of fungal or plant secondary metabolism and thus, belong to the group of modified mycotoxins2. After consumption of contaminated foodstuff, the conjugates can be hydrolyzed by human intestinal microbiota leading to liberation of ZEN that implies an underestimation of the true ZEN exposure. In order to include ZEN conjugates in routine analysis, as well as for toxicological investigation reliable standards are needed.
The objective of the present study was to develop a simple and economic method for biosynthesis of ZEN conjugates. Preceding experiments on the biotransformation of ZEN by Rhizopus and Aspergillus species showed a mixed metabolite formation3. Therefore, these known ZEN conjugating fungal strains were screened for their potential to selectively synthesize the ZEN derivatives ZEN-14-sulfate (Z14S), ZEN-14-glucoside (Z14G) and ZEN-16-glucoside (Z16G). The screening was conducted by adding ZEN to liquid fungal cultures. Cultivation conditions and ZEN incubation time were varied. All media samples were analyzed for metabolite formation by HPLC-MS/MS. Z14S was exclusively formed by A. oryzae. Under optimized conditions a specific biosynthesis of Z14G by R. oryzae and Z16G by R. oligosporus was achieved. After liquid-liquid-extraction and preparative chromatographic cleanup 1H-NMR purities of ≥ 73% for Z14S, ≥ 82% for Z14G and ≥ 50% for Z16G were obtained. In addition, a consecutive biosynthesis was developed by first using Fusarium graminearum for ZEN biosynthesis on rice based liquid medium. After inactivation of Fusarium the subsequent conjugation reaction was conducted utilizing Aspergillus and Rhizopus species under the various optimized conditions.
In this study an easy and cost-efficient biosynthesis for Z14S, Z14G and Z16G was developed. The developed biosynthesis could be also used for other metabolites like ZEL conjugates. Our results of the in vitro screening indicate also the formation of a ZEL-glucoside and α ZEL-sulfate as major metabolites by R. oryzae. In sum, under optimized cultivation conditions fungi can be easily utilized for a targeted and stereospecific synthesis of ZEN conjugates.
Gegenstand der vorzustellenden Arbeiten ist die Prüfung der Umwelt-beständigkeit und -verträglichkeit von Materialien und Produkten hinsichtlich der Emission von potenziellen Schadstoffen in die Umwelt. Hierzu werden chemisch-physikalische Einflüsse (Bewitterung) und mikrobielle Beanspruchungen an Modellmaterialien evaluiert. So werden die Freisetzungsraten von Schadstoffen in Abhängigkeit der Beanspruchung beschrieben. Als Modellmaterialien kommen die Polymere Polystyrol (PS) und Polypropylen (PP) zum Einsatz. Synergistische Effekte der Bewitterungsparameter und der mikrobiologischen Beanspruchung sollen dabei ebenso betrachtet werden, wie die gezielte Alterung. Auch findet eine Beschreibung des Verhaltens der ausgetragenen Schadstoffe in den Umweltkompartimenten Boden oder Wasser statt. Hier sind mit Hilfe der zu entwickelnden Screening- und non-Target-Analyseverfahren die Transformation und der Metabolismus durch Mikroorganismen zu beschreiben. Aus den Ergebnissen sollen Korrelationen zwischen den künstlichen Alterungsverfahren und realen Szenarien abgeleitet werden.
Gegenstand der vorzustellenden Arbeiten ist die Prüfung der Umweltbeständigkeit und -verträglichkeit von Materialien und Produkten hinsichtlich der Emission von potenziellen Schadstoffen in die Umwelt. Hierzu werden chemisch-physikalische Einflüsse (Bewitterung) und mikrobielle Beanspruchungen an Modellmaterialien evaluiert. So werden die Freisetzungsraten von Schadstoffen in Abhängigkeit der Beanspruchung beschrieben. Als Modellmaterialien kommen die Polymere Polystyrol (PS) und Polypropylen (PP) zum Einsatz, die jeweils mit polybromierten Flammschutzmitteln (PBFSM) versehen sind. Synergistische Effekte der Bewitterungsparameter und der mikrobiologischen Beanspruchung sollen dabei ebenso betrachtet werden, wie die gezielte Alterung. Auch findet eine Beschreibung des Verhaltens der ausgetragenen Schadstoffe in den Umweltkompartimenten Boden oder Wasser statt. Hier sind mit Hilfe der zu entwickelnden Screening- und non-Target-Analyseverfahren die Transformation und der Metabolismus durch Mikroorganismen zu beschreiben. Auch soll mit Hilfe der RFA und der LA-ICP-MS die Abreicherung der PBFSM in den Modellmaterialien beschrieben werden. Aus den Ergebnissen sollen Korrelationen zwischen den künstlichen Alterungsverfahren und realen Szenarien abgeleitet werden.
Ammoniakemissionen in die Umwelt erfolgen insbesondere durch die Landwirtschaft (93,6 %), aber auch durch Verbrennungsprozesse in der die Abfallwirtschaft (2,3 %) und den Straßenverkehr (1,8 %). Dieser Stoff ist selbst in geringen Konzentrationen nicht nur eine Geruchsbelästigung, sondern auch eine Substanz mit ökologischer und klimatischer Relevanz.
Die Bestimmung von Ammoniak in relevanten Konzentrationen von kleiner 25 μg m-3 erfolgt im Allgemeinen über NH4+ als Analyten, spektralfotometrisch oder mit der Ionenchromatographie nach Überführung in die flüssige Phase. Wegen der niedrigen Konzentrationen an Ammoniak in der Außenluft wird meist eine gesammelte Probe verwendet oder die Bestimmung erfolgt nach einer aktiven, anreichernden Probenahme.
Die eigenen Arbeiten sollen dazu beitragen, die Ammoniak-Bestimmung in der Außenluft präziser, sowie schneller und kostengünstiger zu machen.
Die BAM prüfte daher kommerzielle elektrochemische und Metalloxid-basierte Sensoren, die für diesen Konzentrationsbereich aber nur bedingt geeignet sind. Deshalb wurden alternativ eigene Entwicklungen zum Nachweis von Ammoniak im Spurenbereich aufgenommen, wobei der Analyt über die Änderung der Fluoreszenz eines BODIPY-Farbstoffs bei 550 nm mittels eines portablen Fluoreszenz-Sensors direkt aus der Gasphase gemessen wird.
Zur Kalibrierung von Ammoniak-Sensoren und -Messgeräten steht ein stationäres System basierend auf der Mischung von zertifizierten Prüfgasen aus Druckflaschen mit kalibrierten Massendurchfluss-regler (MFC) zur Verfügung. Darüber hinaus erfolgt eine chemische Analyse der verwendeten Gasgemische mittels eines Massenspektrometers.
Für die Kalibrierung und Prüfung von Sensoren und Messgeräten vor Ort wurde ein mobiles Prüfsystem entwickelt. Die Generierung von Ammoniak-haltigen Gasen im Spurenbereich von 0,5 nmol/mol bis 500 nmol/mol erfolgt durch das Permeationsverfahren nach ISO 6145-10.
Für die Realisierung der Rückführbarkeit der Ammoniakbestimmung werden von den Nationalen Metrologischen Instituten sowie designierten Instituten Standards bereitgestellt und auch weiterentwickelt. Die primären metrologischen Standards beruhen auf SI-Einheiten und sind die Basis für eine Rückführbarkeit der Sensoren bzw. Analysengeräte.
Bacterial adhesion on surfaces of medical, water and food applications may lead to infections, water or food spoilage and human illness. In comparison to traditional static and macro flow chamber assays for biofilm formation studies, microfluidic chips allow in situ monitoring of biofilm formation under various flow regimes, have better environment control and smaller sample requirements.
In this work, a novel microfluidic platform is developed to investigate biofilm adhesion under precisely controlled bacteria concentration, temperature, and flow conditions. This platform central unit is a single-inlet microfluidic flow cell with a 5 mm wide chamber designed and tested to achieve ultra-homogenous flow in the central area of chamber. Within this area, defined microstructures are integrated that will disturb the homogeneity of the flow, thus changing bacterial adhesion pattern.
Here we present the monitoring of bacterial biofilm formation in a microfluidic chip equipped with a microstructure known as micro-trap. This feature is based on a 3D bacteria trap designed by Di Giacomo et al. and successfully used to sequester motile bacteria.
At first, fluorescent particles similar in size to Escherichia coli (E. coli) are used to simulate bacteria flow inside the flow cell and at the micro-trap. The turbulences induced by the trap are analyzed by imaging and particle tracking velocimetry (PTV). Secondly, the model strain E. coli TG1, ideal and well described for biofilm studies, is used to analyze biofilm formation in the micro-trap. Therefore, a stable fluorescent strain E. coli TG1-MRE-Tn7-141 is constructed by using Tn7 transposon mutagenesis according to the method described by Schlechter et al. Sequestering of E. coli cells within the micro-trap was followed using epifluorescence microscopy.
The novel microfluidic platform shows great potential for assessment of bacterial adhesion under various flow regimes. The performance of structural feature with respect to the generation of turbulences that promote or reduce bacterial adhesion can be systematically examined.
The combination of flow analysis and fluorescent strain injection into the microfluidic chip shows that the micro-trap is useful for capturing bacteria at defined positions and to study how flow conditions, especially micro-turbulences, can affect biofilm formation. It represents a powerful and versatile tool for studying the relation between topography and bacteria adhesion.
Here, we describe a fast and simple extraction method for the determination of per- and polyfluorinated alkyl substances (PFASs) utilizing extractable organic fluorine (EOF) sum parameter analysis and high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) in soil samples. After extraction and separation of inorganic and organic fluorinated compounds, organically bound fluorinated compounds were indirectly determined via the molecular absorption of gallium mono-fluoride at 211.248 nm. The implementation of the decisions of the “Stockholm Convention on persistent organic pollutants” as well as the “Protocol on Persistent Organic Pollutants of the Convention on Long-Range Transboundary Air Pollution” of the UNECE include the reduction respectively the elimination of PFASs in the environment. Currently, regulations aim to target single compounds (mostly C8-PFAS). But the PFAS group includes over 4700 substances, which are potentially persistent and toxic, thus target analytical approaches are not suitable for a holistic approach investigating the PFAS pollutant situation. Furthermore, forbidden PFASs are substituted by short-chain PFASs, thus the number of unknow substances is steadily increasing. For this reason, sum parameter approaches are more suitable to investigate and assess the pollution situation as well as derive exposure limits. Our developed analytical method was successfully applied to determine PFASs in soil samples from a polluted site. In view of steadily increasing numbers of PFAS substances, our method will make an important contribution in assessing the pollution situation as well as support policy makers in deriving exposure limits for PFAS in the future.