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- Fluorescence (15)
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- 1 Analytische Chemie; Referenzmaterialien (88)
- 6 Materialchemie (76)
- 8 Zerstörungsfreie Prüfung (70)
- 5 Werkstofftechnik (31)
- 4 Material und Umwelt (30)
- 6.6 Physik und chemische Analytik der Polymere (27)
- 6.3 Strukturanalytik (22)
- 1.2 Biophotonik (20)
- 7 Bauwerkssicherheit (20)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (20)
Ziel des Projektes HARFE (Haftfestigkeit Reproduzierbarkeit Festigkeit) war es, eine Er-höhung der Haft- bzw. Klebfestigkeit auf Niedrigenergie-Polymeren (PE, PP, PTFE) zu erreichen. SENTECH realisierte dazu plasmachemische Oberflächenaktivierungen mit O2 und die Abscheidung von Aluminiumoxidschichten (Al2O3) mittels Atomic Layer Deposition (ALD), wobei die Ellipsometrie zum in-situ Monitoring der ALD-Prozesse diente. Die BAM charakterisierte die modifizierten Oberflächen bezüglich der Oberflächenenergie (OFE) und bestimmte die Verbund- bzw. Klebfestigkeit mittels der Zentrifugentechnologie
Over the last few years, there has been a growing interest to apply spectroscopic methods to the agricultural field for better understanding of soil properties and for efficient, sustainable management of arable land. Within the project I4S (intelligence for soil), funded by the BMBF, an integrated system for site-specific soil fertility management is developed, consisting of different sensors like X-Ray fluorescence analysis (XRF), near-infrared spectroscopy (NIR) and laser-induced breakdown spectroscopy (LIBS). LIBS provides a fast and simultaneous multi-element analysis with little to no sample preparation, which makes it a suitable method for real-time analysis on the field.
The quantification of macro and micro nutrients in soils with LIBS is challenging due to matrix effects, different levels of moisture content and varying grain sizes. First studies revealed that the problems with matrix effects can be overcome by using well characterised soils as reference materials and chemometric tools like Partial Least Squares Regression (PLSR) for calibration.
The next step was to investigate the influence of moisture and grain sizes on the LIBS signal, which is a big issue when measuring directly on the field. The results showed that the LIBS signal decreases exponentially with increasing moisture content, as most of the laser energy is used for vaporising the water. With moisture contents of 30 % or higher almost no signal can be detected. This decrease is more severe for sandy soils than for clay soils. First tests of different grain size distributions indicate that the variation of the LIBS signal increases with growing amounts of larger grains. This results in a higher standard deviation, because of a poorer reproducibility of the plasma formation and plasma characteristic. With the help of chemometric tools the influence of moisture and grain sizes should be implemented in the calibration model for accurate analysis of nutrient composition in agricultural soils.
Coating materials are nowadays often required to deliver not only sufficient barrier performance and suited optical appearance but a broad range of other functional properties. The incorporation of inorganic nanoparticles (NPs) is known to improve many key characteristics and provide new functionalities in polymer materials. Presented work aims to prepare and characterize an organic-inorganic coating material designed to bring together advantageous properties of hybrid materials and reinforcement effect delivered from the inorganic NPs embedment.
Siloxane-based hybrid resins hold great advantages as coating materials as their properties can be tuned between those of polymers and those of glasses, thus, the compositions with superior thermal and mechanical properties can be achieved. We used Cycloaliphatic Epoxy Oligosiloxane (CEOS) resin as a polymeric matrix where the network formation was achieved by UV induced cationic polymerisation. Boehmite Alumina (BA) nanoparticles were added to CEOS resin as a reinforcing agent and resultant material was processed into films either by bar-coating or by spin-coating depending on further characterization procedure. Two different types of BA NPs, hydrophilic and organophilic, were used in order to assess the impact of particles surface on the resin characteristics. CEOS synthesis by condensation reaction was confirmed using 13C and 29Si NMR. Changes in CEOS photocuring process, resulting from particles incorporation, were monitored by real-time IR spectroscopy. At the same time, the thermal behaviour was evaluated by DSC and TGA methods. Morphology of the coatings was investigated by means of SEM operated in transmission mode.
It was observed that BA presence increased the epoxy conversion degree and glass transition temperature. Material formulations providing best film characteristics were determined with regard to the particle type and loading. Compared to the hydrophilic nanoparticles, organophilic BA NPs yield superior overall performance of the foils.
Spheriplex multiplexed immunoassays: A practical tool for environmental, food and bioanalysis
(2019)
Clinical, environmental, and food analysis, require efficient and accurate quantitative analysis. Immunoassays take advantage of highly selective and affine binding of an antibody towards an antigen, being easy-to-use and allowing for high sample throughput. However, common immunoassays, e. g. ELISA are not capable of multiplexed analysis, thus limiting possible applications. On the other hand, multi-analyte methods, e.g. liquid chromatographytandem mass spectrometry requires expensive equipment, trained analysts and the time of analysis usually limits sample throughput. This bottleneck can be overcome combining the suspension array technology, where particles are encoded to allow multiplexed detection, with fluorescence immunoassays to create suspension array fluorescence immunoassays (SAFIA).
Polystyrene core/silica shell microparticles serve as platform for SAFIA. While an encoding dye is introduced in the polystyrene core, the silica shell is used for immobilization: For competitive hapten immunoassays small molecules are immobilized on the surface, serving as a competitive binding site for selective antibodies. For quantification of proteins, antibodies can be immobilized on the surface and the sandwich immunoassay format can be employed. All mentioned immunoassays can be executed wash-free and highly parallelized, allowing up to 500 determinations within three hours. In contrast to ELISA, short incubation times, a wash-free mix-and-read procedure and automated flow-cytometric read-out makes SAFIA applicable for even non-trained personal.
SAFIA showed excellent performance in studies on the origin and fate of drug residues in waste water, which is important to assess clearance rates of wastewater treatment plants. Furthermore, SAFIA can be employed in environmental screenings, detecting pollution of natural river waters by tracking anthropogenic marker substances. It was successfully employed in clinical and food analysis applications, e.g. the quantification of the anti-inflammatory drug diclofenac in breast milk or the quantification of caffeine in beverages. Due to multiplexing capacities, SAFIA can significantly improve biotechnological processes, as in the screening of hybridoma cells for selective and efficient antibody production. For small molecule analytes, limits of detection down to 4 ng/L and for proteins below 25 ng/mL (IgG) were observed, which makes SAFIA applicable to all addressed analytical issues. Moreover, in the analysis of real-world samples, SAFIA shows higher accuracy in contrast to ELISA, indicating higher matrix stability and thus higher robustness in analysis.
Clinical, environmental, and food analysis, require efficient and accurate quantitative analysis. Immunoassays take advantage of highly selective and affine binding of an antibody towards an antigen, being easy-to-use and allowing for high sample throughput. However, common immunoassays, e. g. ELISA are not capable of multiplexed analysis, thus limiting possible applications. On the other hand, multi-analyte methods, e.g. liquid chromatographytandem mass spectrometry requires expensive equipment, trained analysts and the time of analysis usually limits sample throughput. This bottleneck can be overcome combining the suspension array technology, where particles are encoded to allow multiplexed detection, with fluorescence immunoassays to create suspension array fluorescence immunoassays (SAFIA).
Polystyrene core/silica shell microparticles serve as platform for SAFIA. While an encoding dye is introduced in the polystyrene core, the silica shell is used for immobilization: For competitive hapten immunoassays small molecules are immobilized on the surface, serving as a competitive binding site for selective antibodies. For quantification of proteins, antibodies can be immobilized on the surface and the sandwich immunoassay format can be employed. All mentioned immunoassays can be executed wash-free and highly parallelized, allowing up to 500 determinations within three hours. In contrast to ELISA, short incubation times, a wash-free mix-and-read procedure and automated flow-cytometric read-out makes SAFIA applicable for even non-trained personal.
SAFIA showed excellent performance in studies on the origin and fate of drug residues in waste water, which is important to assess clearance rates of wastewater treatment plants. Furthermore, SAFIA can be employed in environmental screenings, detecting pollution of natural river waters by tracking anthropogenic marker substances. It was successfully employed in clinical and food analysis applications, e.g. the quantification of the anti-inflammatory drug diclofenac in breast milk or the quantification of caffeine in beverages. Due to multiplexing capacities, SAFIA can significantly improve biotechnological processes, as in the screening of hybridoma cells for selective and efficient antibody production. For small molecule analytes, limits of detection down to 4 ng/L and for proteins below 25 ng/mL (IgG) were observed, which makes SAFIA applicable to all addressed analytical issues. Moreover, in the analysis of real-world samples, SAFIA shows higher accuracy in contrast to ELISA, indicating higher matrix stability and thus higher robustness in analysis.
Während des Entladungsprozesses interagieren Mikrohohlkathodenentladungen (engl. micro hollow cathode discharges) durch verschiedenste physikalische Phänomene mit ihrer Umgebung. Analog zu Funken- und Koronaentladung treten neben den optischen Erscheinungen auch akustische Wechselwirkungen bis in den Ultraschallbereich auf. Diese Wechselwirkungen sind bisher jedoch nur selten Gegenstand der Forschung gewesen. Durch elektro-chemischen Prozesse und die Stromdichteverteilung während des Zündvorgangs erfährt das angrenzende Fluid eine, durch den thermoakustischen Effekt hervorgerufene, rapide Dichteänderung und erzeugt somit eine akustische Emission. Dieser Beitrag gibt einen Überblick über den letzten Stand der akustischen Beschreibung der Mikrohohlkathode. Weiterhin wird anhand von Anwendungsbeispielen, wie der Charakterisierung von akustischen Sensoren, sowie der Nutzung innerhalb der zerstörungsfreien Werkstoffprüfung, die Nutzung dieser Entladungsart präsentiert. Darüber hinaus erlaubt die Kenntnis hinsichtlich der akustischen Eigenschaften der Entladung wichtige Rückschlüsse im Rahmen der Plasmadiagnostik.
Due to the multi-physical appearance of gas discharges the possibilities of interaction with their surrounding environment are very wide. Some of the most common applications are surface or material modification, light sources and electric propulsion. Since atmosphere pressure plasma generate a huge amount of thermal energy caused by collisions in the sheath, this temperature alternation is also able to produce acoustic waves in the ambient gas volume (as lightning and thunder).
The plasma-chemical interaction provides the most significant Impact to the generated heat and electro-hydrodynamic force, detectable by acoustic sensors. This contribution gives an overview of experimental acoustic analysis of diffuse coplanar surface dielectric barrier discharges and provides a basic physical straight-forward model. In addition to the characterization, possible applications (e.g. plasma acoustic loudspeaker or transducer for air-coupled ultrasonic testing) concerning these discharge types are presented.
Since the early 19th century microorganisms were studied on their capabilities of causing microbiologically influenced corrosion (MIC) of metals. The most studied ones are sulfate-reducing bacteria (SRB), but others can corrode metals as well, e.g. acid-producing bacteria or methanogenic archaea (MA). However, these studies were mostly focused on metals related to the petroleum industry but metals for other industries, e.g. dentistry, are also susceptible to corrosion. The inert Titanium (Ti) is often used as an implant material, but it is a base metal. The formation of a passivating oxide layer allows Ti to be corrosion resistant at normal conditions.
Nonetheless, scanning electron microscope images on dental implants from patients with acute peri-implantitis showed clear signs of corrosion. Currently, the corrosion mechanism of dental implants is unknown, but many indications suggest that oral microorganisms, including MA (Methanobrevibacter oralis) and SRB (Desulfomicrobium orale), could be involved.
To determine if MA or SRB can corrode Ti (pure Ti or Ti-6Al-4V alloy), corrosion rate, methane and sulfide concentrations were analyzed. Electrical potential measurements using in-house developed electrochemical cells indicated a potential change on Ti in the presence of a corrosive MA strain compared to an abiotic control.
Microbial composition comparison will be analyzed using samples from dental pockets of 150 infected patients by considering the quality of the implant and 50 healthy people by means of amplicon sequencing. Enrichments and isolation of pure cultures from the dentals samples are also examined for their corrosion behavior. Overall, this is the first study investigating the susceptibility of dental implant material to corrosion using human related MA.
The future competitiveness of the process industry and their providers depends on its ability to deliver high quality and high value products at competitive prices in a sustain-able fashion, and to adapt quickly to changing customer needs. The transition of pro-cess industry due to the mounting digitalization of technical devices and their provided data used in chemical plants proceeds. Though, the detailed characteristics and con-sequences for the whole chemical and pharmaceutical industry are still unforeseeable, new potentials arise as well as questions regarding the implementation. As the digitali-zation gains pace fundamental subjects like the standardization of device interfaces or organization of automation systems must be answered. Still, process industry lack of sufficient system and development concepts with commercial advantage from this trend.
Compared to traditional batch processes, intensified continuous production allows new and difficult to produce compounds with better product uniformity and reduced con-sumption of raw materials and energy. Flexible (modular) chemical plants can produce various products using the same equipment with short down-times between cam-paigns, and quick introduction of new products to the market.
Full automation is a prerequisite to realize such benefits of intensified continuous plants. In continuous flow processes, continuous, automated measurements and closed-loop control of the product quality are required. Consequently, the demand for smart sensors, which can monitor key variables like component concentrations in real-time, is increasing. Low-Field NMR spectroscopy presents itself as such an upcoming smart sensor1,2 (as addressed, e.g., in the CONSENS project3).
Systems utilizing such an online NMR analyzer benefits through short development and set-up times when applied to modular production plants starting from a desired chemi-cal reaction3. As an example for such a modular process unit, we present the design and validation of an integrated NMR micro mixer based on computational modelling suited for a desired chemical reaction. This method includes a proper design of a con-tinuous reactor, which is optimized through computational fluid dynamics (CFD) for the demands of the NMR sensor as well as for the given reaction conditions. The system was validated with a chemical reaction process.
Acoustic levitators generate acoustic standing waves between a transducer and a concave reflector. These acoustic waves are separated by multiple integer numbers of half wavelengths. Thus, acoustic levitation is the effect that a small volume (5 nL-10 μL) of sample can be levitated in a contact-free manner. Until now, levitation in analytical chemistry has primarily been associated with optical techniques such as Raman, X-Ray or UV/Vis spectroscopy. Less common applications are combinations of acoustic levitation with mass spectrometry. One reason for this being that the acoustic field surrounding the droplet effectively shields the sample, thus making it inaccessible to most ambient ionization techniques. Any effective investigation of acoustically-levitated droplets therefore requires the physical removal of some of the sample from the confine region of the acoustic trap before analysis.
Due to its advantages of being a direct comparison method, quantitative NMR spectroscopy (qNMR) becomes more and more popular in industry. While conventional high-field NMR systems are often associated with high investment and operational costs, the upcoming market of permanent-magnet based benchtop NMR systems show a considerable option for a lot of applications. The mobility of these systems allows to bring them more closely to the real production environment, e.g. for at-line quality control.
In this work we present an interlaboratory comparison study investigating the qNMR performance of state-of-the-art benchtop NMR spectrometers. Therefore, BAM prepared two samples of a mixture of NMR reference standards tetramethylbenzene (TMB) and tetrachloronitrobenzene (TCNB) at concentration levels of 200 mM and 10 mM. These “ready-to-use” samples were sent to participant laboratories, which performed analysis on their benchtop NMR equipment of different vendors and fields from 43 to 80 MHz. Raw data was reported back and further investigated by using different data analysis methods at BAM.
After this very first qNMR comparison study of benchtop NMR spectrometers show promising results, following studies are planned to cover more parts of the qNMR process, e.g. sample preparation and weighing, but also data analysis, as commonly done in similar studies for high-field NMR spectroscopy in industry and metrology.
Bisphenol A (BPA) is a chemical that has been used in the production of plastics for more than 40 years. BPA released from bottles made of polycarbonates has been identified as a potential endocrine disrupting substance. Comprehensive research has been undertaken to test and verify its effect on animals and human beings.
Many methods have been proposed for the determination of BPA, in particular, gas and liquid chromatography. The main disadvantages of such approaches are the high cost of the equipment, the significant duration of an analysis, and difficulties in screening a large number of samples. Lateral Flow ImmunoAssay (LFIA) attributes are high throughput, high specificity and sensitivity, as well as low cost and simplicity.
An LFIA test strip was developed. This LFIA is based on anti-BPA antibodies (from mouse) conjugated with gold nanoparticles as the marker by passive absorption and covalent coupling, deposited in an elaborate pad. To form control and test zones, anti-mouse antibody and a BVA-BSA conjugate were spotted on the nitrocellulose membrane, respectively.
Negative samples are revealed by red lines both in the test and control zones, respectively, whereas positive samples produce a single red line only in the control zone. The measurement range is 0.05 – 23 μg/L, visually detected by the naked eye within 5 minutes. In addition, the intensities at the test line can be read by dedicated lateral flow readers (opTrilyzer® and Cube by opTricon, Berlin) for a more precise and documented determination.
Polymeric core-shell particles were synthesized in a semi-batch emulsion polymerization process. The shell of the particles consist of PVDF with a high amount of beta-phase. Small-angle X-ray scattering (SAXS) was used to quantify the size of the cores of the particles and the thickness of the shell.
There is an increasing interest in bridging the gap between the photoluminescence (PL) properties of nanomaterials like semiconductor nanocrystals (QDs) commonly assessed in ensemble studies and the PL features of single QDs for life sciences applications such as bioimaging studies or use in microfluidic assays. The fluorescence quantum yield (ΦF) is a key performance parameter for all molecular and nanoscale emitters, increasingly employed in nanoscience, nanotechnology, and medical diagnostics.
ΦF determines not only the signal size together with the reporter´s molar extinction coefficient, yet it is particularly relevant for nanocrystals like QDs with coordinatively bound surface ligands and size- and surface chemistry-dependent PL characteristics.
The importance of ΦF measurements at ultralow concentration encouraged us to explore the potential of fluorescence correlation spectroscopy (FCS) for the relative determination of ΦF of ligand-stabilized CdTe nanocrystals in comparison to molecular dyes with closely matching spectral properties and known ΦF.
We describe a FCS-based method for the relative determination of ΦF of dispersed QDs at ultralow concentrations, and procedures to overcome QD-inherent challenges like complex and power-dependent blinking behavior as well as ligand- and QD-specific aggregation. We could demonstrate the potential of this approach by comparison with steady state ensemble measurements.
Absorption edge tomography is a method which exploits the sudden change of the attenuation coefficient, when the photon energy crosses the absorption edge of an element. The beamline BAM line at BESSY II, which is operated by the Federal Institute for Materials Research and Testing, can provide a monochromatized beam in a photon energy range from 5 keV up to 80 keV with a bandwidth of 2%. Together with the microtomography setup, this enables differential tomography sensitive to any element with N >= 24 (Cr) by using an appropriate K- or L-edge in this range. Here, a polymer filament embedding metal organic framework (MOF) was prepared and used for 3D printing. Absorption edge tomography at the copper K edge was employed to perform a non-destructive 3D characterization of the microstructure of the embedded MOF. Data fusion was then used to determine the size distribution of the embedded MOF.
We have applied laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) with subcellular resolution as an elemental mass microscope to investigate the distributions of Ag nanoparticles (NP) in a 3-dimentional multicellular spheroid (MCS) model. The production of MCS has been optimized by changing the seeding cell number (500 to 40,000 cells) and the growth period (1 to 10 days). Incubations of MCS with Ag nanoparticle suspensions were performed with a concentration of 5 µg mL-1 for 24 hours. Thin-sections of the Eosin stained MCS were analysed by elemental mass microscopy using LA-ICP-MS to image distributions of 109Ag, 31P, 63Cu, 66Zn and 79Br. A calibration using NP suspensions was applied to convert the measured Ag intensity into the number of particles being present in each measurement pixel. The numbers of NP determined ranged from 30 up to 4,000 particles in an enrichment zone. The particle distribution was clearly correlated to 31P, 66Zn and 79Br and was localized in an outer rim of proliferating cells (confirmed by DAPI) with a width of about two-single cell diameters. For the highest seeding cell number NPs were only detected in this outer rim, whereas small molecules as for instance 79Br and 109Ag ions were detected in the core of the MCS as well. Aniline blue staining demonstrated that this outer rim was rich in collagen structures in which fibroblast cells were embedded and a thin-membrane was visible which separated the core from the biological active cell layer functioning as biological barriers for NP transport. In this presentation, we will show the possibility using this 3-dimensional model for toxicological and medical applications.
Fiber reinforced polymers (FRPs) are a well established material in lightweight applications, e.g. in automotive, aerospace or wind energy. The FRP components are subjected to multiaxial mechanical as well as hygrothermal loads. Common operation temperatures are in the range of 213 K and 373 K (-60 °C and 100 °C) at a relative humidity of 10% to 90%. In spacecraft applications, the environmental conditions are even more extreme. However, the correlation between multiaxial mechanical loading and harsh environment conditions have to-date not been investigated in detail. The project aims to investigate the fatigue behavior of FRPs dependent on multiaxial mechanical loading, temperature, and humidity. Extensive experimental testing is performed on flat plate and cylindrical tube specimens, accompanied by numerical and analytical calculations.
Intensified continuous processes are in focus of current research. Compared to traditional batch processes, intensified continuous production allows the synthesis of new and difficult producible compounds with better product uniformity and reduced consumption of raw materials and energy. Flexible (modular) chemical plants can produce various products using the same equipment with short down-times between campaigns, and quick introduction of new products to the market.
Full automation is a prerequisite to realize such benefits of intensified continuous plants. In continuous flow processes, continuous, automated measurements and closed-loop control of the product quality are required. Consequently, the demand for smart sensors, which can monitor key variables like component concentrations in real-time, is increasing. Low-Field NMR spectroscopy presents itself as such an upcoming smart sensor (as addressed, e.g., in the CONSENS project1,2).
Systems utilizing such an online NMR analyzer benefits through short development and set-up times when applied to modular production plants starting from a desired chemical reaction. As an example for such a modular process unit, we present the design and validation of an integrated NMR micro mixer based on computational modelling suited for a desired chemical reaction. This method includes a proper design of a continuous reactor, which is optimized through computational fluid dynamics (CFD) for the demands of the NMR sensor as well as for the given reaction conditions. The system was validated with a chemical reaction process.
Using non-optimum combination of manufacturing parameters in selective laser melting (SLM) may lead to reduction of quality of component: defects generation, distortion of geometry and even cracking. Usually, the optimization of parameters is performed by changing volumetric energy density (Ev) and selecting parameters giving low porosity values. However, not only low porosity but also stable microstructure and low residual stresses will help to achieve advanced mechanical behavior of the component.
In present work, we investigated cuboid-shaped Ti-6Al-4V samples produced with different manufacturing parameters. The parameters leading to the same Ev were considered as well as parameters which are not included in Ev. Residual stresses in subsurface region were investigated by synchrotron X-ray diffraction, which allows to penetrate around 100 µm from the surface therefore overcome the problem of high roughness of SLM components without additional sample preparation. Only tensile stresses were found along the building direction, that can play critical role especially during cyclic loading. In parallel, using X-ray computed tomography we also observe that porosity is mainly concentrated in the contour region, except in case where the laser speed is small. However, by using some process parameters it was possible to decrease residual stresses and obtain uniform α+β Ti microstructure and relatively low porosity. Additionally, it was found that not included in Ev (e.g., base plate position, focus distance) should be considered as additional manufacturing parameters during SLM process.
The porosity and the surface roughness are recently discussed problems for SLM parts. The influence of SLM process parameters on porosity is well studied for different materials. Nevertheless, the build angle (i.e. the angle between part orientation and build plate) needs to be understood as an additional SLM process parameter, as it has been shown, that the microstructure and hence the mechanical performance of various materials depend on the build angle. The inherent build angle of each strut as a part of a lattice structure is the motivation to investigate the influence of the build angle on the porosity and roughness on round-shaped (1 mm diameter) struts by means of CT. Conventional Coordinate Measuring Machine (CMM) has the limitation towards small and round shaped samples. The need for Computed Tomography (CT) regarding investigations of SLM parts will increase because no other non-destructive technique allows the assessment of complex geometries with inner laying surfaces. We used CT to assess the pores and the strut surface. Seven struts out of the nickel alloy Inconel 625 with build angles from 30° to 90° were studied. It was found that the number of pores is smaller, and the size of pores is larger for the 90° strut. In case of 30° strut, the number of pores is increased towards down-skin side, additionally, this strut orientation showed to have the largest number of attached powder particles. The elongated pores exist exclusively near the strut surface. While the roughness at the down-skin surface is highly depending of the biud angle, the roughness at the up-skin surface is the same for all struts. The mechanisms of pore and surface roughness formation is not mainly driven by gravity.
Due to its advantages of being a direct comparison method, quantitative NMR spectroscopy (qNMR) becomes more and more popular in industry. While conventional high-field NMR systems are often associated with high investment and operational costs, the upcoming market of permanent-magnet based benchtop NMR systems show a considerable option for a lot of applications. The mobility of these systems allows to bring them more closely to the real production environment, e.g. for at-line quality control.
In this work we present an interlaboratory comparison study investigating the qNMR performance of state-of-the-art benchtop NMR spectrometers. Therefore, BAM prepared two samples of a mixture of NMR reference standards tetramethylbenzene (TMB) and tetrachloronitrobenzene (TCNB) at concentration levels of 200 mM and 10 mM. These “ready-to-use” samples were sent to participant laboratories, which performed analysis on their benchtop NMR equipment of different vendors and fields from 43 to 80 MHz. Raw data was reported back and further investigated by using different data analysis methods at BAM.
After this very first qNMR comparison study of benchtop NMR spectrometers show promising results, following studies are planned to cover more parts of the qNMR process, e.g. sample preparation and weighing, but also data analysis, as commonly done in similar studies for high-field NMR spectroscopy in industry and metrology.
Improvement in deep process understanding is a mandatory prerequisite for the application of modern concepts like Industrial Internet of Things (IIoT) or “Industrie 4.0”. The direct hyphenation with online methods of process analytical technology (PAT) allows profound insights into the actual reactions within chemical and pharmaceutical production steps and provides necessary information for associated advanced control strategies.
While the industrial application of online Raman spectroscopy has already been successfully demonstrated, low-field NMR spectroscopy is not yet adequately developed as a robust online method for use in process industry. The high information content combined with the low calibration effort makes NMR spectroscopy a highly promising method for modern process automation with a high flexibility due to short set-up times and novel calibration concepts. This is a major advantage compared to other analytical methods, especially regarding multi-purpose plant strategies, as well as processes suffering from fluctuating quality of raw materials.
The work presented here focusses on the heterogeneous catalyzed hydrogenation of 2-butyne-1,4-diol, as a step of the synthesis of industrially important solvent tetrahydrofuran. This reaction is proceeding via an intermediate product and suffers from competitive reaction paths. In this application, online NMR and Raman spectroscopy were combined with data from classical process sensors, e.g., pressure, temperature, and flow transducers in a highly automated setup for the development of innovative control concepts.
The transition from the current automation landscape to next generation automation concepts for the process industry has already begun. Smart functions of sensors simplify their use and enable plug-and-play integration, even though they may appear to be more complex at first sight. Monitoring specific information (i.e., “chemical” such as physico-chemical properties, chemical reactions, etc.) is the key to “chemical” process control. Here we introduce our smart online NMR sensor module provided in an explosion proof housing as example.
Due to NMR spectroscopy as an “absolute comparison method”, independent of the matrix, it runs with very short set-up times in combination with “modular” spectral models. These are based on pure component NMR spectra without the need for tedious calibrations runs. We present approaches from statistical, (i.e., Partial Least Squares Regression) to physically motivated models (i.e., Indirect Hard Modelling).
Based on concentration measurements of reagents and products by the NMR analyser a continuous production and direct loop process control were successfully realized for several validation runs in a modular industrial pilot plant and compared to conventional analytical methods (HPLC, near infrared spectroscopy). The NMR analyser was developed for an intensified industrial process funded by the EU’s Horizon 2020 research and innovation programme (“Integrated CONtrol and SENsing”, www.consens-spire.eu).
Additive manufacturing (AM) opens the route to a range of novel applications. However, the complexity of the manufacturing process poses a challenge to produce defect-free parts with a high reliability. Since process dynamics and resulting microstructures of AM parts are strongly influenced by the involved temperature fields and cooling rates, thermography is a valuable tool for process monitoring. Another approach to monitor the energy input into the part during process is the use of optical tomography.
Common visual camera systems reach much higher spatial resolution than infrared thermography cameras, whereas infrared thermography provides a much higher temperature dynamic. Therefore, the combined application increases the depth of information. Here, we present first measurement results using a laser beam melting setup that allows simultaneous acquisition of thermography and optical tomography from the same point of view using a beam splitter. A high-resolution CMOS camera operating in the visible spectral range is equipped with a near infrared bandpass filter and images of the build plate are recorded with long-term exposure during the whole layer exposing time. Thus, areas that reach higher maximum temperature or are at elevated temperature for an extended period of time appear brighter in the images. The used thermography camera is sensitive to the mid wavelength infrared range and records thermal videos of each layer exposure at an acquisition rate close to 1 kHz.
As a next step, we will use computer tomographic data of the built part as a reference for defect detection.
This research was funded by BAM within the focus area Materials.