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Paper des Monats
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Scandium oxide (Sc2O3) is a rare-earth oxide with significant potential in key technological areas, but due to its limited supply a deep understanding of its characteristics in different crystalline phases is still missing. Here, we present a combined experimental and ab initio X-ray absorption spectroscopy investigation of Sc2O3 focusing on excitations from the O K-edge and the Sc L2,3-edge. While measurements are performed on a cubic sample, the most stable phase under ambient conditions, six different polymorphs are computed, including two high-pressure phases with a trigonal and monoclinic lattice in addition to the cubic phase, as well as three computationally predicted structures. Our analysis of the structural and electronic properties reveals significant similarities between the cubic polymorph and the high-pressure trigonal phase, while the monoclinic crystal exhibits distinct features. The spectra simulated for these similar phases from the solution of the Bethe–Salpeter equation show very good agreement with measurements. Additional comparison with results computed in the independent-particle approximation highlights the dominant role of electron–hole correlations in shaping the absorption features, particularly at the O K-edge, where a common pattern with the features of other sesquioxides is identified. Our findings offer new insight into the spectral fingerprints of Sc2O3 polymorphs, aiding in situ characterization and informing sustainable materials management.
Portable benchtop NMR spectrometers enable real-time process and reaction monitoring in contrast to conventional laboratory based off-line gas chromatography or high-field NMR measurements. In this study, benchtop NMR spectroscopy is demonstrated as a process analytical technology (PAT) tool for the application of the solvent extraction step in downstream processing of polyhydroxyalkanoate (PHA) biopolymers. These are one of the few thermoplastic polymers synthesized 100 % via biotechnological routes which fully biodegrade in common natural environments. This makes them excellent candidate materials for sustainable replacement of conventional plastic materials.
Online NMR experiments were conducted using a fully automated setup, employing commercially available PTFE tubing as a flow-cell assembly. Extraction was carried out in a thermostated stirred batch reactor in lab-scale. Single-scan NMR spectra allowed continuous monitoring of the extraction of the PHA copolymer poly-(hydroxybutyrate-co-hydroxyhexanoate) containing 13.5 mol-% hydroxyhexanoate from Ralstonia eutropha biomass. Extractions were performed in chloroform and acetone across ground lyophilized cell loadings ranging from 20 to 120 g/L. The reproducibility and reliability of compact NMR spectroscopy closely matched with high-field NMR measurements. A strong correlation was observed between online low-field NMR data and offline gas chromatography (GC) analysis. The study highlights the versatility of compact NMR for process monitoring, facilitating endpoint determination and enhancing extraction efficiency by optimizing process parameters. Steady-state conditions were achieved within 6 to 10 minutes for chloroform and acetone, respectively, underscoring the method’s value in supporting downstream process development and optimization for PHA recovery.
The widespread contamination of soil and water with perfluoroalkyl substances (PFAS) has caused considerable societal and scientific concern. Legislative measures and an increased need for remediation require effective on-site analytical methods for PFAS management. Here we report on the development of a green-fluorescent guanidine-BODIPY indicator monomer incorporated into a molecularly imprinted polymer (MIP) for the selective detection of perfluorooctanoic acid (PFOA). Complexation of PFOA by the indicator, which is mediated by concerted protonation-induced ion pairing-assisted hydrogen bonding, significantly enhances fluorescence in polar organic solvents. The MIP forms as a thin layer on silica nanoparticles doped with tris(bipyridine)ruthenium(II) chloride, which provides an orange emission signal as internal reference, resulting in low measurement uncertainties. Using a liquid-liquid extraction protocol, this assay enables the direct detection of PFOA in environmental water samples and achieves a detection limit of 0.11 µM. Integration into an opto-microfluidic system enables a compact and user-friendly system for detecting PFOA in less than 15 minutes.
We assessed the quantification of surface amino functional groups (FGs) for a large set of commercial and custom-made aminated silica nanoparticles (SiO2 NPs) with sizes of 20–100 nm, prepared with different sol–gel routes, different amounts of surface amino FGs, and different porosity with four methods providing different, yet connected measurands in a bilateral study of two laboratories, BAM and NRC, with the overall aim to develop standardizable measurements for surface FG quantification. Special emphasis was dedicated to traceable quantitative magnetic resonance spectroscopy (qNMR) performed with dissolved SiO2 NPs. For the cost efficient and automatable screening of the amount of surface amino FGs done in a first step of this study, the optical fluorescamine assay and a potentiometric titration method were utilized by one partner, i.e., BAM, yielding the amount of primary amino FGs accessible for the reaction with a dye precursor and the total amount of (de)protonatable FGs. These measurements, which give estimates of the minimum and maximum number of surface amino FGs, laid the basis for quantifying the amount of amino silane molecules with chemo-selective qNMR with stepwise fine-tuned workflows, involving centrifugation, drying, weighting, dissolution, measurement, and data evaluation steps jointly performed by BAM and NRC. Data comparability and relative standard deviations (RSDs) obtained by both labs were used as quality measures for method optimization and as prerequisites to identify method-inherent limitations to be later considered for standardized measurement protocols. Additionally, the nitrogen (N) to silicon (Si) ratio in the near-surface region of the SiO2 NPs was determined by both labs using X-ray photoelectron spectroscopy (XPS), a well established surface sensitive analytical method increasingly utilized for microparticles and nano-objects which is currently also in the focus of international standardization activities. Overall, our results underline the importance of multi-method characterization studies for quantifying FGs on NMs involving at least two expert laboratories for effectively identifying sources of uncertainty, validating analytical methods, and deriving NM structure–property relationships.
Functionalized nanomaterials (NM) with their unique size-dependent properties are of increasing relevance for current and future developments in various fields such as medical and pharmaceutical industry, computing, electronics or food and consumer products. For instance, NMs are used as drug carriers, fluorescent sensors, and multimodal labels in bio-analytical assays and imaging applications. The performance and safety of NMs are influenced by their intrinsic physicochemical properties. Among these, the surface chemistry of the particles, which is largely determined by the chemical nature and density of functional groups and ligands, plays a crucial role in enhancing the stability, and processability of NMs, as well as their interactions with the environment. Thus, particle standards with well-designed surfaces and methods for functional group quantification can foster the sustainable development of functional and safe(r) NM.[1] To develop simple, versatile, and multimodal tools for quantifying various bioanalytically relevant functional groups (FG) such as amine,[2,3] carboxy,[2] thiol, and aldehyde[4] functionalities, we explored and compared several analytical methods. These methods included electrochemical titration, dye-based optical assays, and other instrumental techniques like nuclear magnetic resonance, mass spectrometry, and thermal analysis. Our multimodal approach’s potential for FG quantification was demonstrated using both commercial and custom-made polymeric and silica particles with different densities of functional groups.
Cadmium is a heavy metal that can be hazardous to environmental and human health, even in trace levels.[1] In this way, the extraction and/or preconcentration of this element from environmental samples, such as river water, is important to obtain information about the composition and monitoring of potential contamination.[2] High-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) is widely used for Cd determination. However, the determination of this element at trace-level can be challenging, especially in complex matrices. Thus, nanoparticles (NPs) can be used as an alternative for the extraction and preconcentration of Cd in environmental samples, minimizing the potential interferences and improving the method´s limit of detection (LOD). Considering that Pd is also widely used as a “universal” chemical modifier, this project aims todevelop PdNPs capped with 3-mercaptopropionic acid (MPA) to assess its potential as a chemical modifier and preconcentration agent for Cd determination by HR-CS GF AAS in river water. In this way, the synthesis of PdNPs was performed in an aqueous medium by using ascorbic acid as a reducing agent. The characterization of PdNPs was performed by checking the size via dynamic light scattering (DLS), transmission electron microscopy (TEM), and inductively coupled plasma mass spectrometer in single particle mode (spICP-MS), where the median size was 56 ± 14 nm. The temperature program of HR-CS GFAAS was optimized for river water under three conditions: using Pd(NO3)2/Mg2+ (0.01%/0.5% m/v) as a chemical modifier (condition A), using Pd NPs as a chemical modifier (condition B), and without chemical modifiers (condition C). The pyrolysis and atomization temperatures for condition A were 900 and 1900 ºC, for condition B were 700 ºC and 1900 ºC, and for condition C were 500 and 1900ºC, respectively. Besides the temperature of pyrolysis for the universal chemical modifier being higher than that of PdNPs, using the PdNPs, the absorbance is significantly greater, according to the t-test for pairs, at a 95% confidence level. In addition, the evaluation of the preconcentration property of the PdNP was performed by adding 1 µg L-1 of Cd2+ in buffer pH 4 in two systems: one with and the other without PdNPs. After 1 h of stirring, both
systems were centrifuged at 3600 rpm for 10 min, and the absorbance in HR-CS GFAAS for Cd in both supernatants was evaluated. According to ANOVA from the t-test, at a 95% confidence level, there was a significant difference in the absorbance, indicating that Cd is interacting with the PdNPs. A multifactorial planning 2k, where k is the number of parameters of the extraction, which was time of extraction (10; 35; 60 min), Volume of Pd NPs (100; 300; 500 µL), pH (3; 5; 7), was used to evaluate the parameters with significant influence in the preconcentration of Cd2+. According to ANOVA, with 95% confidence, there is no lack of fit, and the parameters volume of PdNP and pH significantly influenced the response. In this way, the Doehlert methodology surface will be applied to both significant parameters. The goal is to achieve optimal conditions that increase the extraction efficiency of Cd2+ from environmental samples. The results indicate that the developed material is promising to use as a chemical modifier and for the preconcentration of Cd2+ in environmental samples.
The recovery of critical metals from spent lithium-ion batteries is a key strategy for sustainable resource management and the circular economy. Conventional hydrometallurgical processes typically rely on strong mineral acids and elevated temperatures, which, although effective, generate hazardous waste and demand high energy inputs. As a greener alternative, deep eutectic solvents (DES) combine low toxicity, non-volatility, simple synthesis, and tunable physicochemical properties,
making them promising media for selective metal recovery1-2. Here, we report for the first time the use of ultrasound (US) to assist the leaching of Li and Co from LiCoO₂ black mass employing a deep eutectic solvent based on choline chloride and formic acid (ChCl:HCOOH, 1:2 molar ratio). The DES was synthesized at 90 °C for 3 h under stirring (300 rpm) and was characterized in terms of its molecular structure and formation by 1H-NMR and FT-IR, as well as by its viscosity and density. For each experiment, ~0.100 g of LiCoO2 was treated with 5 g of DES-FA in an ultrasonic bath (35 kHz, 60 °C) for different irradiation times (30–120 min), followed by three sequential extractions. All measurements were performed by ICP OES. Lithium solubilization reached ~80% at 90 min, while cobalt extraction was stabilizing at ~79% after 120 min. The enhanced performance under US is attributed to sonochemical effects that promote cavitation and microjets, leading to the disruption of particle agglomerates, the thinning of diffusion layers, and the generation of highly reactive local environments. These processes accelerate deintercalation and mass transfer
within the solid–liquid interface. Combined with the mild acidity of DES-FA, which enables simultaneous leaching of both metals while favoring faster kinetics for Li,
ultrasound provided a synergistic effect that enhanced the overall process and preserved the distinct extraction profiles of Li and Co. The extraction behavior of the
two metals can be explained by their different speciation in the DES-FA medium. Cobalt is likely reduced from Co(III) to Co(II) by formic acid and stabilized through the formation of chloro-complexes such as [CoCl4]2- with chloride anions from ChCl, favoring its solubilization. In contrast, lithium does not form stable complexes with chloride under these conditions. It is primarily extracted as a solvated cation, stabilized by the extensive hydrogen-bond network of the DES. This difference accounts for the faster leaching kinetics observed for Li compared to Co. Selective recovery was achieved by pHcontrolled precipitation, with cobalt oxalate at pH 4-5 and lithium carbonate at pH 10. The Eco-Scale score of 85 confirmed the greenness of the method. This pioneering approach highlights the potential of coupling DES chemistry with ultrasound. Together, they represent a sustainable and efficient route
for recovering critical metals from battery waste.
Tracing Copper Fungicide Uptake and Distribution in Pea Plants and Soil Using 65Cu Isotope Labeling
(2025)
Copper-based fungicides are commonly used in grain farming to prevent yield losses and undesirable changes in organoleptic properties. However, the ingestion of these compounds can pose significant health risks to humans and animals when exposed through the oral route of absorption. To evaluate whether copper from foliar-applied fungicides can be absorbed and translocated to edible plant tissues, this study investigates the mobility of copper from a copper oxychloride fungicide using 65Cu as a stable isotope tracer. A greenhouse system was established to grow peas (Pisum sativum L.) and simulate agricultural fungicide applications. The 65Cu-labeled copper oxychloride fungicide was synthesized in-house and fully characterized by X-ray diffraction (XRD), Raman spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy. Three applications of the fungicide (0,073g of total copper) were performed in a greenhouse pea growing system, while a control system received ultrapure water. After each application, surface soil, pods, and grains were collected, dried, ground, and digested. Total copper concentrations were measured via ICP OES, and 63Cu/65Cu isotopic ratios were analyzed using ICP-MS. Trends in isotopic ratio and total copper accumulation are visualized through the time series below, indicating the fungicide’s mobility and its accumulation in plant tissues and soil. Samples exposed to the copper fungicide exhibited markedly reduced 63Cu/65Cu isotopic ratios, indicating the uptake of the 65Cu tracer. Pod samples from the treated system showed a sharp decrease, especially after the first application. In the control grains, isotopic ratios stayed consistent throughout the experiment, reflecting the absence of direct contact with the fungicide. Conversely, grains from the treated system showed a consistent decrease in isotopic ratio values throughout the three applications. This pattern suggests a possible mechanism for absorbing or transferring copper isotopes from the pods to the grains, indicating the potential for internal contamination of edible plant tissues, even when the fungicide is applied externally. A similar trend was observed in the topsoil: while isotopic ratios remained constant in the control soil, the treated soil showed a consistent decrease after each application. These findings indicate that the copper fungicide is not only absorbed by aerial plant parts but also accumulates in the soil over time. Altogether, the use of 65Cu isotope tracing proved highly effective in assessing the systemic mobility, transfer, and environmental persistence of copper-based fungicides under controlled greenhouse conditions.
Single-event analysis of discrete entities using microwave-induced nitrogen plasma–mass spectrometry
(2025)
ICP-MS has become a standard for (ultra)trace elemental analysis due to its excellent sensitivity and multi-element capabilities. However, its widespread use is hampered by spectral interferences—especially in the low mass range (<81 amu)—primarily arising from Ar-based polyatomic ions, such as ArO+ and Ar2+, which compromise the accurate quantification of key elements like Fe and Se.1 Over the years, improvements such as collision/reaction cells and sector-field configurations have
helped mitigate these interferences, albeit often at the cost of instrument complexity and increased operational burden.The microwave-induced nitrogen plasma (MINP) source, sustained by microwaves at atmospheric pressure and using nitrogen as the plasma gas, offers a fundamentally different plasma environment. Nitrogen is not only more economical (40-60%) and readily available than Ar, but also avoids the generation of problematic Ar-based interferences. While MINP had been previously applied in optical emission and bulk mass spectrometry,2 its implementation in single-event detection had not yet been demonstrated.
This study pioneers the application of MINP-MS in single-event mode for real-time, high-throughput characterization of NPs, cells, and MPs. The evaluation began with Fe2O3 NPs monitoring the 56Fe nuclide, with a limit of detection of 8.6 ag for Fe, equivalent to a particle size threshold of 19 nm—surpassing the detection capabilities of quadrupole-based ICP-MS systems. Size distribution results
obtained by SP-MINP-MS for Fe2O3 NPs (20–70 nm) matched closely with transmission electron microscopy (TEM) and dynamic light scattering (DLS), confirming the method’s accuracy.
For Se, despite its high ionization energy, metallic SeNPs (150 and 250 nm) were reliably quantified by monitoring 80Se. A calibration curve constructed using SeNP standards yielded excellent linearity (R2 = 0.9994). This approach was further extended to single-cell analysis, using Se-enriched yeast (SELM-1 CRM) as a model. A transport efficiency-independent calibration strategy was employed, relying on SeNPs to determine Se content per cell. The results showed strong agreement with data from conventional SC-ICP-MS, with average Se masses of ~65 fg per cell, validating the
performance of SC-MINP-MS for biological systems. Additionally, the instrument's capability to handle large, low atomic number particles was demonstrated via the analysis of polystyrene (PS) and polytetrafluoroethylene (PTFE) MPs. These MPs (2.5–3.0 µm) were quantified by monitoring 12C+ signals and applying a calibration strategy using citric acid as a standard. The resulting size distributions closely matched nominal sizes, reinforcing the system’s robustness for micrometer-sized polymeric materials. Event durations ranging from 470 to over 900 µs were consistent with literature values for single-entity ICP-MS and correlated well with particle size.
These findings establish single-event MINP-MS as a promising analytical platform for analyzing discrete entities. It provides significant advantages over conventional Ar-based ICP-MS, including reduced interferences, lower operational cost, and comparable or superior sensitivity for analytes such as Fe and Se. By avoiding the limitations of Ar-based plasmas and enabling accurate quantification across a wide range of particle types and sizes, MINP-MS in single-event mode opens new avenues for high-resolution, interference-free elemental analysis at the individual entity level.
The widespread use of pharmaceuticals has led to their persistent presence in various environmental compartments, raising concerns about ecological and human health risks since they pose a significant threat to non-target organisms and human health, necessitating robust methods for environmental risk assessment.
Traditional analytical methods, such as liquid chromatography-mass spectrometry (LC-MS), offer high sensitivity and specificity but are often resource-intensive, require complex sample preparation, limiting their applicability for large-scale or real-time monitoring. In this context, antibody-based analytical techniques present a promising complementary approach for the detection and quantification of pharmaceutical residues in environmental matrices.
Antibodies, due to their high specificity and affinity, enable the development of immunoassays such as ELISA, lateral flow assays, fluorescence-based formats, and electrochemical sensors that are rapid, cost-effective, and adaptable to field conditions. These methods can be tailored to target a wide range of pharmaceutical compounds, including antibiotics and endocrine disruptors. Moreover, antibody-based assays facilitate high-throughput screening and can be integrated into portable platforms for on-site analysis, thereby enhancing temporal and spatial resolution in environmental monitoring.
This presentation explores the potential of antibodies in environmental risk assessment, focusing on their application in detecting trace levels of pharmaceuticals in water, soil, and biota. They are presented as a complementary and powerful tool for rapid, cost-effective screening in the lab and that also can be deployed for on-site analysis in the field.
The talk also discusses recent advances in antibody engineering, multiplexing capabilities [1], and the integration of immunoassays with sensor technologies [2].
Case studies illustrate how immunoanalytical data can help in finding potential contamination hotspots [3], hazard identification, pollution source tracking, and the generation of crucial data for predictive models on environmental fate and effects. Antibody-based methods can also help in early warning systems and the evaluation of mitigation strategies, contributing to a more comprehensive and proactive risk assessment framework, eventually to regulatory decision-making, ultimately aiding in the protection of ecosystems and public health.