1 Analytische Chemie; Referenzmaterialien
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Per- and polyfluoroalkyl substances (PFAS) are a large group of emerging organic pollutants that contaminate the environment, food, and consumer products. They have a wide range of applications due to their water- and oil-repellent properties, as well as their chemical and thermal stability. However, the use of PFAS has raised concerns due to their persistence in the environment and their adverse health effects, leading to regulations aimed at controlling their use and minimizing exposure. Substances such as PFOS, PFHxS, and PFOA are listed in the Stockholm Convention on Persistent Organic Pollutants (POP Regulation, EU 2019/1021). Maximum levels have been set for PFAS in environmental matrices such as water and soil.
Reliable PFAS analysis leads to an increasing global demand for certified reference materials (CRM). However, CRMs for PFAS in soils are rare or currently not available. To improve the metrological infrastructure and support environmental PFAS measurements, a CRM for PFAS in soil (BAM-U027) based on ISO 17034 and ISO 33405 was developed. This poster provides an overview of the different steps for the preparation and characterization of BAM-U027. The assignment of the certified mass fractions for 13 relevant PFAS targets compounds is based on isotope dilution HPLC-MS/MS at three independent workplaces. The results of the BAM in-house certification study on BAM-U027 were supported by an interlaboratory comparison study (ILC) involving 17 participating laboratories in Germany.
BAM-U027 is intended for analytical quality control and contributes to improving environmental protection.
Materials‐based gas capture and storage is an increasingly important area of research. Robust and accurate determination of material properties is required for judicial selection of materials for specific applications and for engineering materials–based systems at scale. One key property is the strength of the adsorbate–adsorbent interaction often quantified via the isosteric enthalpy of adsorption. The heat of adsorption can be measured directly through calorimetry; however, a more widely used approach is to apply the Clausius‐Clapeyron (CC) equation to adsorption isotherms collected at different temperatures. While this approach appears to be straightforward, there exist multiple variants in the application of the methodologies employed. This raises the question on how these variations may or may not affect the determined results. Presented here is a discussion of the most common methodologies and a comparison of indirect determinations (via CC) of the isosteric enthalpy of adsorption by different laboratories on identical material. Included in that comparison are discussions on the measurement and analysis reproducibility. Importantly, details of the methodologies are shown to be critical when comparing enthalpies among laboratories, and different methodologies contribute to significant discrepancies and artifacts in the results. Recommendations are provided to promote robust determination and the reporting thereof.
Preparation workflows of fluorescent nm- and µm-sized polymer particles used as reporters in fluorescent assays, bioimaging, and sensing studies or calibration tools for fluorescence methods in the life sciences can be time-consuming and labor-intensive. Also, the outcome can be operator dependent. Here, we present simple and cost-efficient automated workflows for dye loading and surface labeling of polystyrene particles (PSP), using a commercial self-programmable pipetting robot. For developing and fine-tuning automated staining workflows, hydrophobic Nile Red (NR) was incorporated into 100 nm, 200 nm, and 1000 nm PSP by an adapted swelling procedure of premanufactured particles in the presence of hydrophobic dyes, thereby confirming its reliability and versatility. Subsequent expansion of our automation concept to the labeling of carboxylated PSP with pH-sensitive 6-aminofluorescein (6-AMF) and aminated PSP with pH-responsive fluorescein isocyanate (FITC) demonstrated its broad applicability. All automated workflows were optimized and validated by gravimetry and spectroscopic measurements with a microtiter plate (MTP) reader in absorption and fluorescence mode to ensure particle recovery and reproducible fluorescence features and determine PSP dye loading and labeling efficiencies. Comparison with the manual fabrication of NR-stained PSP using an established swelling protocol showed that our automation approach utilizing a pipetting robot considerably reduced the variability in particle recovery and dye loading efficiency. Overall, our simple, labor- and time-efficient workflows with inexpensive and broadly available commercial automation tools present attractive alternatives to manual particle loading and labeling and provide the basis for fast parameter screening, parallel processing, and decreased hands-on time.
The reconstruction of the thermal history of anthropogenic materials is crucial for understanding historical manufacturing techniques. Preparatory parameters such as firing temperature, heating and cooling rates, soaking time, and kiln atmosphere significantly affect the chemical and structural properties of the final product. Comparing historical materials with replicas produced under well-defined laboratory conditions helps identify indicators for these parameters. This comparative approach is greatly enhanced by spectroscopic analyses. Raman spectroscopy has proven to be a powerful tool in this field due to its high sensitivity to crystal-chemical alterations and high spatial resolution.
The results of thermal experiments with gypsum and carbonate raw materials at burning temperatures up to 1000 °C are presented. Precise measurements of Raman peak positions and Raman band widths enable the differentiation of chemically similar phases. Changes in the Raman band parameters are evident even after the subsequent hydration-hardening process of the fired samples, allowing the spectral discrimination of samples treated at different temperatures steps. These findings from the thermal experiments are further applied to Raman micro-spectroscopic mappings of medieval and reenacted mortars. The extracted Raman band parameters show comparable values between the experimental and real-life samples, proving Raman spectroscopy as a suitable tool for estimating the burning temperature and thus elucidating the manufacturing procedures of anthropogenic materials.
Comprehensive Structure–Property Mapping of Tuned Mechanical Flexibility in Organic Cocrystals
(2026)
Mechanically flexible crystals offer unique opportunities for adaptive materials, yet predictive control over their responses remains a major challenge. Here, we present a chemically unified series of 4-nitrophenol-based cocrystals, cocrystallized with bipyridyl linkers of varied geometries, to systematically map structure–property relationships. Subtle variations in interplanar angles and intermolecular interactions, such as π–π stacking and hydrogen bonding, enable tuning of mechanical responses ranging from brittle fracture to different extents of elastic bending and plastic bending or twistability. This design differs from previous strategies that relied primarily on van der Waals interactions or halogen bonding to impart mechanical compliance to organic crystals. Structural analysis, supported by energy framework calculations, explains the divergent mechanical behaviors. Notably, the studied cocrystal series spans all four canonical structure–property quadrants, manifested through mechanical flexibility, photoluminescence activity, or both. This systematic and comparative study highlights the delicate interplay between molecular packing and supramolecular interactions, providing structure–property correlations that inform emerging design principles for multifunctional crystalline materials for targeted applications.
The increasing demand for alkali-metal batteries, lithium and sodium, highlights the importance of recycling approaches. For batteries which encompass low-value components such as cobalt-free and sodium-ion, a requirement for low-cost and low-energy processes for recovery and reuse. In this respect, direct recycling, is preferred where the functional structure of active materials is preserved. In this study, a direct recycling route for sodium nickel-iron-manganese-copper oxide cathode material for sodium-ion batteries was investigated and preliminary results reveal the challenges in this direct recycling approach. Commercial sodium-ion battery cells were safely disassembled in a Glovebox and the positive electrode material was extracted via ice stripping. The recovered electrode material was structurally and compositionally characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD), and inductive coupled plasma optical emission spectroscopy (ICP-OES) to assess morphology, crystallinity, and elemental stoichiometry.
Optofluidic Sensor for Rapid and Sensitive Detection of Faecal Pigments in Water Quality Monitoring
(2026)
According to the World Health Organization (WHO), at least two billion people worldwide rely on drinking water sources contaminated with faeces.1 UNICEF reports that current methods for detecting faecal contamination are often expensive, time-consuming (typically requiring 18–24 hours), and generally unsuitable for on-site analysis.2 Hence, there is an urgent need for rapid analytical methods that can reliably assess drinking water quality directly in the field.
Our approach utilizes the weak intrinsic fluorescence of faecal pigments such as urobilin (UB), whose emission is enhanced through complexation with Zn²⁺ in alcoholic media, known as Schlesinger’s test. However, this classical method for faecal contaminant detection has significant limitations: UB–Zn²⁺ complexes exhibit only weak fluorescence in water, their fluorescence decays over time, and is interfered by fluorescence from humic substances naturally present in surface waters. These limitations in detection in aqueous media motivated us to explore an organic–aqueous extraction system using hexanol to improve fluorescence response and signal stability.
To address this, we present a dual strategy involving the use of different Zn²⁺ salts and hexanol as an extraction and fluorescence-enhancing medium. We observed a clear dependence of the fluorescence yield of UB–Zn²⁺ complexes on the counter anions of different Zn²⁺ salts. Among them, UB–Zn(NO₃)₂ complex was showing the highest fluorescence intensity in hexanol. The extraction of UB–Zn²⁺ complexes into hexanol provided enhanced and temporally stable fluorescence emission for a reliable sensing approach.3 The photophysics of the UB–Zn²⁺ complex in hexanol and Job’s plots confirmed non-trivial complex stoichiometries. Nonetheless, the developed analytical method showed sensitive (nano- and sub-nanomolar concentration) response for UB detection with negligible fluorescence interference from humic substances commonly present in environmental water.
Furthermore, a 3D-printed optofluidic platform was developed to perform in-channel extraction and real-time fluorescence detection. This platform was printed all at once using a commercial SLA printer with high resolution and transparent resins. The fluidic part allowed for droplet-based extraction by chaotic advection, by means of a miniaturized pump. The optical detection combined an LED for excitation and a USB photomultiplier tube module for low fluorescence signal digital acquisition, potentially on an embedded device such as a tablet. This configuration enabled rapid, sensitive, and interference-minimized detection of faecal pigments in water, demonstrating the potential of optofluidic sensing for on-site water quality monitoring.
Immuno-detection biosensors represent a prominent and recognized field within the classical analytical tools. Their popularity stems not only from their selectivity but also from their remarkable sensitivity. However, in applications where trace detection is required, especially with small molecules, sensitivity can become a limitation. For example, this is the case in forensic analysis where the in-situ detection of explosives remains a challenge due to the limited availability of sensitive sensor platforms. In this work, we present an optical biosensor for the highly specific and sensitive detection of Home-Made Explosives (HME). The immunoassay system is placed in a hydrogel environment that is permeable to the analyte and transparent to light interrogating the fluorescently labelled antibodies. The readout of the immunoanalytical system is realized with Supercritical Angle Fluorescence (SAF). This advanced microscopy technique, facilitates the fluorescence detection at the surface level discriminating bulk emission. To achieve this, we have used a commercially available high-resolution (< 22 µm) SLA printer to fabricate a SAF element. Prior to fabrication, an optical simulation was performed to validate the accuracy of the system’s light path for optimum SAF collection. This affordable technology, with a short fabrication time and no design constraints, grants us the freedom to fabricate a parabolic optical element out of transparent resin specifically tailored to collect the emission generated at the interface of the immunoanalytical system. In order to obtain an antibody-specific interface, glass surface was functionalised with the hapten related to the target analyte. In this way, a surface with non-covalently attached labelled antibodies is obtained, making possible their displacement, and, hence, SAF modulation. Aiming at a new generation of sensors, which not only can meet the requirements of trace detection, but can also be used for substance identification, the combination of immunoanalytical recognition with SAF detection offers a modularity and versatility that is, in principle, well suited to the measurement of target analytes at trace levels.
Magnetic resonance imaging (MRI) is a powerful imaging technique for diagnostic purposes and is frequently used in clinical routine. Typically, non-specific gadolinium-based contrast agents (GBCAs) are used to improve the image quality. Such contrast agents have been in use for more than 35 years, yet their interaction with tissue components is still not fully understood. Typically, they go into the extracellular space. The extracellular matrix (ECM) is a three-dimensional network of macromolecules providing structural and biochemical support of the surrounding cells in all mammalian tissues. It is composed of structural proteins (e.g., collagen, elastin) and proteoglycans, which consist of glycosaminoglycans (GAGs) covalently bound to a protein core. GAGs are long, linear polysaccharides composed of repeating disaccharide units that differ in molecular mass, disaccharide structure and degree of sulfation. Many diseases, including inflammation and tumor invasion, are associated with characteristic ECM changes, especially at an early stage of disease development. Characteristic of GAGs is their ability to form complexes with cations, e.g., with lanthanides. Thus, GAGs could be a potential binding partner for GBCA molecules as a whole or for dechelated Gd.
In this study we investigated the interaction of ionic Gd and GBCAs with tissue components using spheroids with different ECM expressions as model systems. Chinese hamster ovary (CHO) cells and CRL-2242 cells, a CHO mutant that does not produce GAGs, were used to prepare spheroids. These were then incubated with gadolinium chloride and various linear and macrocyclic GBCAs. To study the uptake and distribution two complementary element mapping techniques were used – laser ablation in combination with inductively coupled plasma time-of-flight mass spectrometry and synchrotron radiation nano X-ray fluorescence spectroscopy, which offers sub-cellular resolution. In addition to Gd, other elements such as Fe, P and S were also measured.
Although all spheroids were exposed to identical Gd concentrations, differences were observed. After incubation with GBCAs, Gd is detected in the interior of both types of spheroids. In contrast, incubation with gadolinium chloride leads to Gd enrichment in the outer regions and to much higher Gd contents compared to incubation with GBCAs.
However, due to biological variability, further experiments are needed to elucidate such complex processes as the interaction of GBCAs with ECM components.
BPA unterliegt einer kontinuierlichen behördlichen Kontrolle und ist als besonders besorgniserregender Stoff (SVHC) gelistet. Besondere Besorgnis besteht hinsichtlich seines häufigen Nachweises in Oberflächengewässern, obwohl es leicht biologisch abbaubar ist. In mehreren Studien wurden die Quellen und Wege von BPA in die Umwelt untersucht, wobei festgestellt wurde, dass seine Hauptverwendung als Monomer in PC nur marginal zu den BPA-Freisetzungen in die Umwelt über seinen Lebenszyklus beiträgt.
Um die tatsächlichen Freisetzungen von BPA aus PC unter umweltrelevanten Bedingungen besser zu verstehen, wurde eine neu entwickelte Methodik (Bundesanstalt für Materialforschung und -prüfung, BAM) angewendet, die ein neuartiges beschleunigtes Bewitterungsprotokoll für Polycarbonat-Materialien in Kombination mit einem sensitiven Analysenverfahren umfasst, welches eine Bestimmung von BPA im Ultraspurenbereich ermöglicht. Das Bewitterungsprotokoll erreicht eine 13,6-fache Beschleunigung im Vergleich zu mitteleuropäischen Wetterbedingungen und simuliert Umweltstressoren (globale Strahlung, Regen, Temperaturschwankungen) in einer Bewitterungskammer, wobei gleichzeitig die BPA-Freisetzung mit einem validierten LC-MS/MS-Verfahren unter Verwendung einer organischen Isotopenverdünnungskalibrierung bestimmt wird. In parallelen Freilandversuchen wurden die Trübung und die Vergilbung („Yellowness-Index“) der zu untersuchenden Proben als Referenzparameter untersucht.