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Analytische Methoden für die Quantifizierung von Mikroschadstoffen (Synonym für Spurenstoffe) und Pathogenen im Wasser sind eine Grundvoraussetzung für die Umsetzung des Ziels Nr. 6 für Nachhaltige Entwicklung der UN, weltweit sauberes Wasser zur Verfügung zu stellen. Dafür sind schnelle, einfach zu bedienende und kostengünstige Überwachungssysteme notwendig. Antikörperbasierte Biosensoren haben das Potential, z.B. die Eliminationsleistung bezüglich kleiner organischer Moleküle durch die vierte Reinigungsstufe von Kläranlagen vor Ort zu überwachen. Darüber hinaus kommt modernen bioanalytischen Verfahren bei der Quantifizierung von Pathogenen eine immer wichtigere Rolle zu. Neben einer Bestandsaufnahme zu diesen Themen ist es das Ziel dieses Beitrags, die Anwendungsbarrieren von Biosensoren für die Wasseranalytik von Mikroschadstoffen abbauen zu helfen und die Vorzüge moderner bioanalytischer Methoden für die Quantifizierung von Pathogenen aufzuzeigen.
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 presence of endocrine-disrupting compounds (EDCs) in water poses a significant threat to human and animal health, as recognized by regulatory agencies throughout the world. The Yeast Estrogen Screen (YES) assay is an excellent method to evaluate the presence of these compounds in water due to its simplicity and capacity to assess the bioaccessible forms/fractions of these compounds. In the presence of a compound with estrogenic activity, Saccharomyces cerevisiae cells, containing a lacZ reporter gene encoding the enzyme β-galactosidase, are induced, the enzyme is synthesised, and released to the extracellular medium. In this work, a YES-based approach encompassing the use of a lacZ reporter gene modified strain of S. cerevisiae, microcarriers as solid support, and a fluorescent substrate, fluorescein di-β-D-galactopyranoside, is proposed, allowing for the assessment of EDCs’ presence after only 2 h of incubation. The proposed method provided an EC50 of 0.17 ± 0.03 nM and an LLOQ of 0.03 nM, expressed as 17β-estradiol. The assessment of different EDCs provided EC50 values between 0.16 and 1.2 × 103 nM. After application to wastewaters, similar results were obtained for EDCs screening, much faster, compared to the conventional 45 h spectrophotometric procedure using a commercial kit, showing potential for onsite high-throughput screening of environmental contamination.
Alternative Tools (AT) such as on-site test kits, on-site portable devices and continuous measuring devices, are useful to improve water quality assessment under EU directives, and water treatment processes, thus contributing to improving water management, as well as get insights on the dynamic of pollutants within water bodies. Although these tools have clear advantages (e.g. fast response allowing for real-time monitoring, ease-of-use, lower cost), they are perceived as less reliable than conventional analytical methods. Their alternative nature, innovative status, and non-standard operation mode require specific validation strategies that differ significantly from those of conventional analytical methods. Nevertheless, the validation of ATs, especially on-site test kits, portable devices and continuous measuring devices for water quality monitoring is crucial to support their acceptance, promote their use and make their application sustainable. In this paper, a validation procedure in 4 steps is proposed: (1) Comprehensive description of the AT; (2) Assessment of intrinsic metrological performance and operational factors within a single laboratory; (3) Assessment of inter-laboratory performances through an inter-laboratory comparison and, (4) Demonstration of the equivalence of results between the AT and a reference method. This paper discusses each step of the validation procedure, and examples to illustrate critical issues are provided.
The non-steroidal anti-inflammatory drug (NSAID) diclofenac (DCF) is an important environmental contaminant occurring in surface waters all over the world, because, after excretion, it is not adequately removed from wastewater in sewage treatment plants. To be able to monitor this pollutant, highly efficient analytical methods are needed, including immunoassays. In a medical research project, monoclonal antibodies against diclofenac and its metabolites had been produced. Based on this monoclonal anti-DCF antibody, a new indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed and applied for environmental samples. The introduction of a spacer between diclofenac and the carrier protein in the coating conjugate led to higher sensitivity. With a test midpoint of 3 mg L−1 and a measurement range of 1–30 mg L−1, the system is not sensitive enough for direct analysis of surface water. However, this assay is quite robust against matrix influences and can be used for wastewater. Without adjustment of the calibration, organic solvents up to 5%, natural organic matter (NOM) up to 10 mg L−1, humic acids up to 2.5 mg L−1, and salt concentrations up to 6 g L−1 NaCl and 75 mg L−1 CaCl2 are tolerated. The antibody is also stable in a pH range from 3 to 12. Cross-reactivity (CR) of 1% or less was determined for the metabolites 40-hydroxydiclofenac (40-OH-DCF), 5-hydroxydiclofenac (5-OH-DCF), DCF lactam, and other NSAIDs. Relevant cross-reactivity occurred only with an amide derivative of DCF, 6-aminohexanoic acid (DCF-Ahx), aceclofenac (ACF) and DCF methyl ester (DCF-Me) with 150%, 61% and 44%, respectively. These substances, however, have not been found in samples. Only DCF-acyl glucuronide with a cross-reactivity of 57% is of some relevance. For the first time, photodegradation products were tested for cross-reactivity. With the ELISA based on this antibody, water samples were analysed. In sewage treatment plant effluents, concentrations in the range of 1.9–5.2 mg L−1 were determined directly, with recoveries compared to HPLC-MS/MS averaging 136%.
Concentrations in lakes ranged from 3 to 4.4 ng L−1 and were, after pre-concentration, determined with an average recovery of 100%
Luminophore stained micro- and nanobeads made from organic polymers like polystyrene (PS) are broadly used in the life and material sciences as luminescent reporters, for bead-based assays, sensor arrays, printable barcodes, security inks, and the calibration of fluorescence microscopes and flow cytometers. Initially mostly prepared with organic dyes, meanwhile luminescent core/shell nanoparticles (NPs) like spherical semiconductor quantum dots (QDs) are increasingly employed for bead encoding. This is related to their narrower emission spectra, tuneability of emission color, broad wavelength excitability, and better photostability. However, correlations between particle architecture, morphology, and photoluminescence (PL) of the luminescent nanocrystals used for encoding and the optical properties of the NP-stained beads have been rarely explored. This encouraged us to perform a screening study on the incorporation of different types of luminescent core/shell semiconductor nanocrystals into polymer microparticles (PMPs) by a radical-induced polymerization reaction. Nanocrystals explored include CdSe/CdS QDs of varying CdS shell thickness, a CdSe/ZnS core/shell QD, CdSe/CdS quantum rods (QRs), and CdSe/CdS nanoplatelets (NPLs).
Thereby, we focused on the applicability of these NPs for the polymerization synthesis approach used and quantified the preservation of the initial NP luminescence. The spectroscopic characterization of the resulting PMPs revealed the successful staining of the PMPs with luminescent CdSe/CdS QDs and CdSe/CdS NPLs. In contrast, usage of CdSe/CdS QRs and CdSe QDs with a ZnS shell did not yield luminescent PMPs. The results of this study provide new insights into structure–property relationships between NP stained PMPs and the initial luminescent NPs applied for staining and underline the importance of such studies for the performance optimization of NP-stained beads.
Fluorescent labels have strongly contributed to many advancements in bioanalysis, molecular biology, molecular imaging, and medical diagnostics. Despite a large toolbox of molecular and nanoscale fluorophores to choose from, there is still a need for brighter labels, e.g., for flow cytometry and fluorescence microscopy, that are preferably of molecular nature. This requires versatile concepts for fluorophore multimerization, which involves the shielding of dyes from other chromophores and possible quenchers in their neighborhood. In addition, to increase the number of readout parameters for fluorescence microscopy and eventually also flow cytometry, control and tuning of the labels’ fluorescence lifetimes is desired. Searching for bright multi-chromophoric or multimeric labels, we developed PEGylated dyes bearing functional groups for their bioconjugation and explored their spectroscopic properties and photostability in comparison to those of the respective monomeric dyes for two exemplarily chosen fluorophores excitable at 488 nm. Subsequently, these dyes were conjugated with anti-CD4 and anti-CD8 immunoglobulins to obtain fluorescent conjugates suitable for the labeling of cells and beads. Finally, the suitability of these novel labels for fluorescence lifetime imaging and target discrimination based upon lifetime measurements was assessed. Based upon the results of our spectroscopic studies including measurements of fluorescence quantum yields (QY) and fluorescence decay kinetics we could demonstrate the absence of significant dye-dye interactions and self-quenching in these multimeric labels. Moreover, in a first fluorescence lifetime imaging (FLIM) study, we could show the future potential of this multimerization concept for lifetime discrimination and multiplexing.
A systematic series of industrial-relevant polystyrene-based anion exchange resins that are functionalized with hydro- or fluorocarbon chains are compared regarding their adsorption behavior toward perfluorocarboxylic acids (PFCA) in respect to their charge, chain length, and type of chain. The results clearly show the dominance of electrostatic interactions in the adsorption process as uncharged adsorber materials showed no adsorption at all. In contrast, the charged adsorber materials showed in general a PFCA removal of 80% to 30% over the experiment depending on effluent fraction.
Unexpectedly, for perfluorobutanoic acid (PFBA) the highest removal rate is found with consistently >90%. Despite observing significant benefits in the adsorption of PFCA for fluoroalkylated adsorbers in comparison to their non-fluorinated counterparts, this effect of fluoroalkylation is comparatively small and can not be clearly attributed to fluorophilic interactions between the fluoroalkyl chains. These findings help clarifying that the introduction of fluorocarbon moieties in adsorber materials is not necessary in order to remove fluorocarbon molecules from the environment.
We introduce a passive smart dust concept as a novel solution for environmental monitoring. Utilizing chemical reagents like colorimetric indicators and other chemosensors, these particles detect varying environmental conditions. We developed paper-based sensors that are both cost-effective and eco-friendly. In practical tests, these sensors, dispersed over a designated area, successfully identified hazardous substances by changing their color when exposed to acids or bases. This color change was remotely detectable using a drone-mounted color camera. The data thus obtained was processed through specialized software, accurately pinpointing areas of contamination. This method proves the efficacy and scalability of passive smart dust technology for real-time, environmentally sustainable remote sensing of hazardous materials
Use/distribution of cost-effective and biocompatible pieces of cellulose paper as passive optical chemosensors and readout by the camera system.
Modification of the paper surface using various chemically sensitive dyes (indicators) provides an optically detectable reaction and conclusions about the target substances and precise location.
Amphiphilic nanogels (ANGs) are promising carriers for hydrophobic cargos such as drugs, dyes, and catalysts.
Loading content and release kinetics of these compounds are controlled by type and number of hydrophobic groups in the amphiphilic copolymer network. Thus, understanding the interactions between cargo and colloidal carrier is mandatory for a tailor-made and cargo-specific ANG design. To systematically explore the influence of the network composition on these interactions, we prepared a set of ANGs of different amphiphilicity and loaded these ANGs with varying concentrations of the solvatochromic dye Nile Red (NR). Here, NR acts as a hydrophobic model cargo to optically probe the polarity of its microenvironment. Analysis of the NR emission spectra as well as measurements of the fluorescence quantum yields and decay kinetics revealed a decrease in the polarity of the NR microenvironment with increasing hydrophobicity of the hydrophobic groups in the ANG network and dye–dye interactions at higher loading concentrations. At low NR concentrations, the hydrophobic cargo NR is encapsulated in the hydrophobic domains. Increasing NR concentrations resulted in probe molecules located in a more hydrophilic environment, i.e., at the nanodomain border, and favored dye–dye interactions and NR aggregation.
These results correlate well with release experiments, indicating first NR release from more hydrophilic network locations. Overall, our findings demonstrate the importance to understand carrier–drug interactions for efficient loading and controlled release profiles in amphiphilic nanogels.
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.
Homochirality is an obvious feature of life on Earth. On the other hand, extraterrestrial samples contain largely racemic compounds. The same is true for any common organic synthesis. Therefore, it has been a perplexing puzzle for decades how these racemates could have formed enantiomerically enriched fractions as a basis for the origin of homochiral life forms. Numerous hypotheses have been put forward as to how preferentially homochiral molecules could have formed and accumulated on Earth. In this article, it is shown that homochirality of the abiotic organic pool at the time of formation of the first self-replicating molecules is not necessary and not even probable. It is proposed to abandon the notion of a molecular ensemble and to focus on the level of individual molecules. Although the formation of the first self-replicating, most likely homochiral molecule is a seemingly improbable event, on a closer look, it is almost inevitable that homochiral molecules have formed simply on a statistical basis. In this case, the non-selective leap to homochirality would be one of the first steps in chemical evolution directly out of a racemic “ocean”. Moreover, most studies focus on the chirality of the primordial monomers with respect to an asymmetric carbon atom. However, any polymer with a minimal size that allows folding to a secondary structure, would spontaneously lead to asymmetric higher structures (conformations). Most of the functions of these polymers would be influenced by this inherently asymmetric folding. To summarize, simple and universal mechanisms may have led to homochiral self-replicating systems in the context of chemical evolution. A homochiral monomer pool is deemed unnecessary and probably never existed on primordial Earth.
Organotin compounds (OTCs) have been widely used in anti-fouling paints, pesticide formulations, and as stabilizers in polyvinyl chloride over the past century. In marine ecosystems, OTCs can cause severe damage to biodiversity, leading up to the extinction of vulnerable species. Due to the extensive use of tributyltin (TBT) as a biocide on ship hulls, it has been considered one of the most hazardous substances intentionally introduced into the aquatic environment. This resulted in a global ban on TBT-containing products in the 2000s. However, recent studies indicate the emerging presence of organotin pollutants.
OTCs are known to persist and accumulate in marine sediments, posing a long-term threat to the environment. These harmful substances can be set free and dispersed even after several decades. Therefore, analyzing sediment probes is imperative for a thorough monitoring of pollution. However, species-specific analysis of OTCs at required concentration levels in complex environmental matrices remains challenging. Chromatographic systems are commonly used for their analysis, but the required sample preparation is time-consuming and prone to contamination and analyte loss. The coupling of electrothermal vaporization and inductively coupled plasma-mass spectrometry (ETV/ICP-MS) demonstrates high potential as a rapid, convenient, and chemical-saving scanning tool for environmental samples.
This method enables the direct on-line fractionation of organic compounds from an inorganic fraction and provides element-specific detection at ultra-trace levels without complex sample preparation. Since OTCs are generally more toxic than ionic or elemental tin, analyzing them as a sum parameter is advantageous. Additionally, the determination of both organic and inorganic tin, rather than just organic tin, reveals valuable information about the fate of OTCs. The main challenge in obtaining accurate quantitative data using direct solid sampling techniques like as ETV/ICP-MS is applying a suitable calibration strategy. Our isotope dilution approach overcomes matrix effects in ETV/ICP-MS analysis and is compatible with commercial systems.
PFAS (Per- and polyfluoroalkyl substances) are a widespread and emerging environmental problem due to their longevity and ubiquitous spread. The common structural motif of this compound class is the fluorine – carbon bond on an alkyl backbone, which are known for their chemical inertness and combination of hydrophobicity and oleophobicity. The downside of those properties is the general lack of usable molecular interactions for adsorption to extract them from the environment. The notable exception to that inertness are fluorine – fluorine interactions, which are stronger, the longer the perfluorinated chain length is. Therefore, in this project we investigated the effect of fluorination, length and presence of a charge on the alkyl chain on an adsorber. Towards that goal, in total 16 different adsorber materials were synthesized (fluorinated/non-fluorinated; C4/ C6/ C8/ C10 ; positive charge/no charge) and tested in regard to their potential to adsorb PFOA and perfluoralkylic acids of differing chain lengths. The PFAS concentration was tested via LC-MS/MS to determine the adsorption rate on the various materials. Further work includes the transition from a target analytics to sum parameter analysis for future evaluation of adsorber materials in PFAS environmental samples like river samples. Therefore a quarterly sampling and extraction of spree surface water samples was planned.
Per- and polyfluoroalkyl substances (PFAS) have received global public attention because of their wide distribution in aquatic environments and potential adverse effects to humans and wildlife. Due to the lack of analytical standards and the enormous numbers of these compounds, current target-based methods (e.g., LC-MS/MS) are not suitable for the analysis of new/unknown PFAS and transformation products. Therefore, PFAS sum parameter analysis is becoming increasingly important. For PFAS determination of surface waters, solid phase extraction (SPE) is commonly implemented for clean-up and pre-concentration of samples.
Thus, within this work, single-layer SPE methods (based on Strata™-X, Strata™-X-AW, Strata™-NH2 and Oasis-HLB) were investigated for maximum PFAS coverage utilizing extractable organically bound fluorine (EOF) analysis. Thereby, the optimization procedure relied on the analysis of 3 surface water samples in Berlin, Germany, which were affected by the effluent discharge of wastewater treatment plants. To analyse the SPE elution profiles for EOF and inorganic fluorine, high resolution-continuum source-graphite furnace molecular absorption spectroscopy (HR-CS-GFMAS) and ion chromatography (IC) were used, respectively.
Highest EOF concentrations were achieved by using Strata-X/Strata-XAW as SPE sorbents and methanol as eluent. Furthermore, combinations of the most promising SPE sorbents were selected (X/XAW, XAW/X, HLB/X and WAX/GCB) to extract a wider range of PFASs. By comparing multi-layer SPE methods, lower EOF concentrations were obtained for all investigated combination phases compared to the analysed single phases. For the commercially available combination phase Strata-PFAS (WAX/GCB) for all three river water samples, lower EOF concentrations (1.5 times lower) were determined compared to Strata-X.
The results have shown that single-layer SPE systems are currently superior compared to combination phases for PFAS sum parameter analysis. The multi-layer SPE methods need further optimization regarding appropriate sorbent combinations, loading volumes and elution conditions. The developed single-layer SPE methods can help to elucidate pollutions hotspots and discharge routes.
This contribution reports the development of a polymerizable BODIPY-type fluorescent probe targeting small-molecule carboxylates for incorporation into molecularly imprinted polymers (MIPs). The design of the probe crosslinker includes a urea recognition site p-conjugated to the 3-position of the BODIPY core and two methacrylate moieties. Titration experiments with a carboxylate-expressing antibiotic, levofloxacin (LEVO), showed a blue shift of the absorption band as well as a broadening and decrease in emission, attributed to hydrogen bonding between the probe’s urea group and the carboxylate group of the antibiotic. Using this probe crosslinker, core–shell particles with a silica core and a thin MIP shell were prepared for the detection of LEVO. The MIP exhibited highly selective recognition of LEVO, with an imprinting factor of 18.1 compared to the non-imprinted polymer. Transmission electron microscopy confirmed the core–shell structure and spectroscopic studies revealed that the receptor’s positioning leads to a unique perturbation of the polymethinic character of the BODIPY chromophore, entailing the favourable responses. These features are fully preserved in the MIP, whereas no such response was observed for competitors such as ampicillin. The sensory particles allowed to detect LEVO down to submicromolar concentrations in dioxane. We have developed here for the first time a BODIPY probe for organic carboxylates and incorporated it into polymers using the imprinting technique, paving the way for BODIPY-type fluorescent MIP sensors.
Homochirality is an obvious feature of life on Earth. On the other hand, extraterrestrial samples contain largely racemic compounds. The same is true for any common organic synthesis. Therefore, it has been a perplexing puzzle for decades how these racemates could have formed enantiomerically enriched fractions as a basis for the origin of homochiral life forms. Numerous hypotheses have been put forward as to how preferentially homochiral molecules could have formed and accumulated on Earth. In this article, it is shown that homochirality of the abiotic organic pool at the time of formation of the first self-replicating molecules is not necessary and not even probable. It is proposed to abandon the notion of a molecular ensemble and to focus on the level of individual molecules. Although the formation of the first self-replicating, most likely homochiral molecule, is a seemingly improbable event, on a closer look, it is almost inevitable that some homochiral molecules have formed simply on a statistical basis. In this case, the non-selective leap to homochirality would be one of the first steps in chemical evolution directly out of a racemic “ocean”. Moreover, most studies focus on the chirality of the primordial monomers with respect to an asymmetric carbon atom. However, any polymer with a minimal size that allows folding to a secondary structure would spontaneously lead to asymmetric higher structures (conformations). Most of the functions of these polymers would be influenced by this inherently asymmetric folding. Furthermore, a concept of physical compartmentalization based on rock nanopores in analogy to nanocavities of digital immunoassays is introduced to suggest that complex cell walls or membranes were also not required for the first steps of chemical evolution. To summarize, simple and universal mechanisms may have led to homochiral self-replicating systems in the context of chemical evolution. A homochiral monomer pool is deemed unnecessary and probably never existed on primordial Earth.
The 2023 Nobel Prize in Chemistry was awarded to Aleksey I. Ekimov (prize share 1/3), Louis E. Brus (prize share 1/3), and Moungi G. Bawendi (prize share 1/3) for groundbreaking inventions in the field of nanotechnology, i.e., for the discovery and synthesis of semiconductor nanocrystals, also termed quantum dots, that exhibit size-dependent physicochemical properties enabled by quantum size effects. This feature article summarizes the main milestones of the discoveries and developments of quantum dots that paved the road to their versatile applications in solid-state lighting, display technology, energy conversion, medical diagnostics, bioimaging, and image-guided surgery.
The plant secondary metabolite families of coumarin and 4-hydroxy coumarin have a broad pharmacological spectrum ranging from antibacterial to anticancer properties. One prominent member of this substance class is the synthetic but naturally inspired anticoagulant drug and rodenticide warfarin (coumadin). A vast number of publications focus on the identification of warfarin and its major cytochrome P450-mediated phase I metabolites by liquid chromatography (LC) with mass spectrometry (MS) and tandem mass spectrometric (MS/MS) detection techniques. For the first time, electron ionization (EI) induced high-resolution quadrupole time-of-flight mass spectrometric (HR-qToF-MS) data of in-liner derivatized warfarin and selected hydroxylated species is provided in this study as an alternative to LC-MS/MS approaches. Furthermore, the characteristic fragments and fragmentation pathways of the analyzed methyl ethers are concluded. The obtained data of analytical standards, specific deuterated and 13C-labeled compounds prove inductive cleavage of the acyl or acetonyl side chain, methyl migration, and H-migration, along with consequential inductive cleavage as predominant fragmentation routes. Based on the HR-spectral data, commonalities and differences between the analyzed compounds and fragment groups were evaluated with future applicability in structure elucidation and spectra prediction of related compounds.
The emission of ultrafine particles from small desktop Fused Filament Fabrication (FFF) 3D printers has been frequently investigated in the past years. However, the vast majority of FFF emission and exposure studies have not considered the possible occurrence of particles below the typical detection limit of Condensation Particle Counters and could have systematically underestimated the total particle emission as well as the related exposure risks. Therefore, we comparatively measured particle number concentrations and size distributions of sub-4 nm particles with two commercially available diethylene glycol-based instruments – the TSI 3757 Nano Enhancer and the Airmodus A10 Particle Size Magnifier. Both instruments were evaluated for their suitability of measuring FFF-3D printing emissions in the sub-4 nm size range while operated as a particle counter or as a particle size spectrometer. For particle counting, both instruments match best when the Airmodus system was adjusted to a cut-off of 1.5 nm. For size spectroscopy, both instruments show limitations due to either the fast dynamics or rather low levels of particle emissions from FFF-3D printing in this range. The effects are discussed in detail in this article. The findings could be used to implement sub-4 nm particle measurement in future emission or exposure studies, but also for the development of standard test protocols for FFF-3D printing emissions.
AbstractSince the 1950s, Warfarin has been used globally as both a prescription drug and a rodenticide. Research has shown that warfarin and other rodenticides are present in the environment and food chain. However, emerging contaminants are subject to degradation by biotic and abiotic processes and advanced oxidation processes. In some cases, detecting the parent compound may not be possible due to the formation of structurally changed species. This approach aims to identify hydroxylated transformation products of warfarin in a laboratory setting, even after the parent compound has undergone degradation. Therefore, the Fenton reaction is utilized to insert hydroxylation into the parent compound, warfarin, by hydroxyl and hydroperoxyl radicals generated by Fe2+/Fe3+ redox reaction with hydrogen peroxide. Using multiple reaction monitoring, a GC–MS/MS method, incorporating isotopically labeled reference compounds, is used to quantify the expected derivatized species. The analytes are derivatized using trimethyl-3-trifluoromethyl phenyl ammonium hydroxide, and the derivatization yield of warfarin is determined by using isotopically labeled reference compounds. The method has a linear working range of 30 to 1800 ng/mL, with detection limits ranging from 18.7 to 67.0 ng/mL. The analytes are enriched using a C18-SPE step, and the recovery for each compound is calculated. The Fenton reaction generates all preselected hydroxylated transformation products of warfarin. The method successfully identifies that 4′-Me-O-WAR forms preferentially under the specified experimental conditions. By further optimizing the SPE clean-up procedures, this GC–MS-based method will be suitable for detecting transformation products in more complex matrices, such as environmental water samples. Overall, this study provides a better understanding of warfarin’s degradation and offers a robust analytical tool for investigating its transformation products.
Here, we report a comparative study of different sum parameter analysis methods for the extraction of per- and polyfluoroalkyl substances (PFAS) from manufactured consumer products, which can be measured by combustion ion chromatography (CIC). Therefore, a hydrolysis-based extraction method was further developed, which accounts for the addition of hydrolyzable covalently bound polyfluoroalkylated side-chain polymers (SFPs) to the extractable organic fluorine portion of the mass balance proposed as "hydrolyzable organically bound fluorine" (HOF). To test this hypothesis, the method was applied to 39 different consumer products containing fluoropolymers or monomeric PFAS taken from four different categories: outdoor textiles, paper packaging, carpeting, and permanent baking sheets. We also evaluated the method's efficiency by extracting four synthesized fluorotelomer polyacrylate reference compounds. The total fluorine (TF) and extractable organically bound fluorine (EOF) values were measured through CIC using established protocols. The TF values ranged from sub-ppb to %-levels, depending on the compound class. All samples showed results for hydrolyzed organofluorine (HOF) between 0.03 and 76.3 μg/g, while most EOF values were lower (<LOD to 58.1 μg/g). Moreover, the methods were contrasted with the "total hydrolyzable precursor" (THP) assay analyzed using gas-chromatography coupled mass spectrometry (GC-MS), which yielded concentrations of 6:2–10:2 fluorotelomer alcohols (<LOD-568 μg/g) for textile and paper samples. Furthermore, targeted analytical investigation of 25 compounds via liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) was conducted and accounted for significantly lower sum amounts (<LOD-0.98 μg PFAS/g). To estimate the fluorine mass balance of all methods, the fluorine levels of target analytical data were calculated and compared to the sum parameter values and evaluated. Finally, the efficiency of the extraction method was approximated by the recovery analysis of four selected SFP model compounds compared to their TF values, yielding 36.7–74.0% after extraction and 3.8–36.3% after processing the extract for the HOF sum parameter.
Der Vortrag beschreibt den Stand der Arbeiten an der BAM, Fachbereich Umweltanalytik zur Entwicklung von Sensoren für die Wasseranalytik. Er stellt die bisherigen Arbeiten da, die ausgehend von ELISAs, zunehmend portable Plattformen wie FPIA und LFIA umfassen. Beas-based Formate werden von mikrotiterplatten-basierten Techniken auf mikrofluidische Lab-on-Chip-Systeme übertragen, die bei geeigneter Miniaturisierung und Automatisierung als Sensorsysteme angesehen werden können. Der Vortrag endet mit einem Blick auf ein laufendes Monitoring-Projekt von anthropogenen Markern in Abwasser und charakterisiert die Treiber, die die Entwicklung von Sensoren für die Wasseranalytik in den letzten Jahren vorantreiben.