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Isotope analysis is a tool for material research. For example, it may provide information about the provenance of a sample or changes in dynamic systems. Here is presented optical spectroscopy as an analytical alternative to mass spectrometry for isotope quantification based on the isotopic shift of atoms and diatomic molecules.
Calcium isotope analysis can be an important tool for paleoclimate studies of the carbon cycle, as well in carbon capture technology, but its utility is limited by challenges using conventional mass spectrometry. We propose a new fast, precise, and high-throughput technology based on multiple complementary high-resolution spectroscopies analyzed by machine-learning.
Wie lässt sich die Herkunft von Rohstoffen, Lebensmitteln oder Umweltschadstoffen einfacher, schneller und kostengünstiger als mit bisherigen Methoden bestimmen?
Die Dissertation zeigt auf, dass man das grundlegende physikalische Prinzip einer Isotopverschiebung mit in Adlershof entwickelten Optik-Instrumenten für die Herkunftsbestimmung nutzen kann. Die entwickelte Methode ermöglicht es in Zukunft den Ursprung von Rohstoffen, Lebensmitteln oder Umweltschadstoffen kostengünstiger und wesentlich schneller bestimmen, als dies mit bisherigen Methoden möglich ist.
Kann man das grundlegende physikalische Prinzip einer Isotopieverschiebung mit einem Optik-Instrument für die Herkunftsbestimmung nutzen? Carlos Abad hat eine wegweisende Methode entwickelt, die es in Zukunft ermöglicht den Ursprung von Rohstoffen, Lebensmitteln oder Umweltschadstoffen kostengünstiger und wesentlich schneller bestimmen, als dies mit bisherigen Techniken möglich ist.
Following fluorinated drugs by molecular absorption spectrometry – from cancer cells to body fluids
(2018)
Fluorine has been widely introduced into pharmaceutical drugs. Due to the high C-F bond strength, a single atom substitution with fluorine produces drastic desirable and tunable changes in the molecular properties. However, the clinical monitoring of these drugs is not straightforward.
Organofluorine compounds are elusive for a non-targeted analysis; a significant problem in fluorine determination is the lack of suitable detection techniques. Standard atomic absorption and emission spectrometers cannot access fluorine, because their resonance lines lie in the VUV spectral range below 100 nm. In the case of conventional inductively coupled argon plasmas (ICP), the plasma energy is too low to generate a significant population of excited fluorine atoms. Recently, our group introduces high-resolution continuum source absorption spectrometry (HR-CS MAS) as a new way for the indirect monitoring of fluorinated compounds. Main benefits of HR-CS-MAS includes low limits of detection, complete analyte recovery, simple to no sample preparation, and short time analysis.
Society for Applied Spectroscopy (SAS) Atomic Section Student Award.
Magnesium is a major element in the hydrosphere and biosphere and plays important roles in (bio-) geochemical and physiological cycles. Mg has three stable isotopes, 24Mg, 25Mg and 26Mg. It is due to their relatively large mass difference (~8% between) that isotope fractionation leads to slight variations of isotope amount ratios in biological, environmental and geological samples. Traditionally, isotope ratios are measured by mass spectrometric methods. Their drawbacks include the high costs for instruments and their operation, experienced operators and elaborate time-consuming chromatographic sample preparation.
Recently, optical spectrometric methods have been proposed as faster and low-cost alternative for the analysis of isotope ratios of selected elements by means of high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS), and laser ablation molecular isotopic spectrometry (LAMIS).
For the determination of Mg isotope ratios in selected rock reference materials, the molecular spectrum of the in-situ generated MgF and MgO molecules were studied and their results compared with MC-ICP-MS. By HR-CS-MAS, samples were dissolved by acid digestion and Mg isotopes analyzed with and without matrix. The absorption spectrum was recorded for MgF for the electronic transitions X 2Σ → A 2 Πi, and X 2Σ → B 2Σ+. In the case of LAMIS, we investigated the MgF molecule for the electronic transition A 2Πi → X 2Σ, as well as direct analysis by the MgO molecule for the electronic transition A 1Π+ → X 1Σ. The MgF and MgO spectra are described as the linear combination of their isotopic components or isotopologues: 24MgF, 25MgF, and 26MgF for the MgF and 24MgO, 25MgO, and 26MgO for the MgO. The isotope analysis was done by deconvolution of the MgF spectrum by partial least square regression (PLS) calibrated with enriched isotope spikes. Results were accurate with precisions ranging between 0.2 ‰ and 0.8 ‰ (2 SD, n= 10) for HR-CS-GFMAS. No statistically significant differences were observed for samples w/o matrix extraction. On the other hand, LAMIS allows the direct analysis of solid samples with the extended possibility of direct analysis, however the precision is lower due the lack of solid isotopic calibration standards.
Advances and Applications of Molecular Absorption Spectrometry: from Non-Metals to Isotope Analysis
(2020)
The present work covers two main aspects of high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS), an analytical technique for elemental trace analysis.
First, a comprehensive mechanistic study of molecule formation in graphite furnaces is presented, which is a key step into the recovery of analytical signals. For this, the molecule formation of CaF was studied, which is used for the indirect analytical determination of fluorine in HR-CS-GFMAS. A zirconium coating catalyzes the CaF formation, and its structure was investigated. The kinetics of this reaction was established by monitoring its molecular spectrum at different atomisation temperatures. An Arrhenius plot showed a pseudo-first order reaction with respect to fluorine (n = 1). An intermediate state was isolated, and its structure was elucidated by spectroscopic methods: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XANES and EXAFS), and Raman microspectroscopy. Here a mechanism is proposed, where ZrO2 works as a heterogeneous catalyst: after a pyrolytic step, an intermediate state of ZrO(OCaF) is activated, and at higher temperatures, CaF(g) is released from the zirconium-coated graphite surface.
Second, analytical methods were developed by using HR-CS-MAS as detector for non-metals and isotope analysis. Therefore, the determination of organic absorbable chlorine in water, the quantification of fluorine in consume care products with declared perfluorinated ingredients, and the determination of sulfur content in crude oils were investigated. Finally, the high resolution of the instrumentation allows to measure isotopic shifts with high precision in some observed molecular spectra. Consequently, the molecular spectra of enriched isotopes of boron and magnesium were investigated, establishing so the potential of HR-CS-MAS for the accurate and precise determination of isotopic amount ratios.
Magnesium is a major element in the hydrosphere and biosphere, and it is direct correlated with the carbon cycle. Therefore, the study of its isotopic fractionation in sediments and sea water helps to understand the earth’s climate and global warming. Mg has three stable isotopes, 24Mg, 25Mg and 26Mg, and traditionally isotope amount ratios are measured by mass spectrometric methods. Their drawbacks include the high costs for instruments and their operation, experienced operators and elaborate time-consuming chromatographic sample preparation. Recently, an optical spectrometric method has been proposed as faster and low-cost alternative for the analysis of isotope ratios: high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS).
For the determination of Mg isotope ratios in selected rock reference materials, the high-resolution molecular absorption spectrum of in-situ generated MgF molecule was studied applying multivariate analysis and the results compared with MC-ICP-MS. Samples were dissolved by acid digestion and Mg isotopes analyzed with and without matrix extraction. The absorption spectra were recorded for MgF for the electronic transition X 2Σ → B 2Σ+. The MgF spectrum is described as the linear combination of their isotopic components or isotopologues: 24MgF, 25MgF, and 26MgF. The isotope analysis was done by deconvolution of the MgF spectrum by partial least square regression (PLS). A PLS model was built and calibrated with enriched isotope spikes and certified reference materials. Spectra data was preprocessed by a derivate of second order and venetian blinds cross-validation was employed for finding the optimum latent variables. Finally, the model was refined by a genetic algorithm which identified the best subset of variables for a precise and accurate regression. Results are compatible with those obtained by MC-ICP-MS with an accuracy of ± 0.3‰ with uncertainties ranging between 0.02 to 0.6‰. This accuracy and precision discriminate the isotope fractionation in geological samples, and it is suitable for earth’s climate studies.
Small variations in the isotopic composition of some elements have been used as proof of provenance of mineral and biological samples, to describe geological processes, and to estimate a contamination source. Routinely, isotope compositions are measured by mass spectrometry; the working horse of the isotope analysis. However, mass spectrometric methods are expensive, time-consuming and they require a high qualified analyst.
Here, an alternative faster and low-cost optical method for isotope ratio determination is investigated: high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS). Stable isotope amount composition of X = Li, B, Mg, Ca and Sr have been determined by monitoring the absorption spectra of their in situ generated hydrides (XH) in graphite furnace HR-CS-MAS. For example, the system of two stable isotopes of boron (10B and 11B) was studied via its hydride for the electronic transition X1Σ+ → A1Π (Fig. 1a). The spectrum of a given sample is a linear combination of the 10BH molecule and its isotopologue 11BH. Therefore, isotopic composition of samples and reference materials are calculated by a partial least square regression (PLS). For this, a spectral library is built by using samples with known isotope composition. Results are metrologically compatible with those reported by mass spectrometric methods. [1] Similar results are obtained for n isotope systems like Mg (24Mg, 25Mg, and 26Mg), where isotope shift of their isotopologues can be resolved as shown in Fig.1 b. The extension of this methodology to other elements like Li, Ca and Sr is discussed [2].
References:
[1] C. Abad, S. Florek, H. Becker-Ross, M.-D. Huang, H.-J. Heinrich, S. Recknagel, J. Vogl, N. Jakubowski, U. Panne, Determination of boron isotope ratios by high-resolution continuum source molecular absorption spectrometry using graphite furnace vaporizers, Spectrochim. Acta, Part B, 136 (2017) 116-122.
[2] C. Abad et al., unpublished results, 2018.
Magnesium is a naturally occurring element that can be found in several mineral forms in the earth crust. This element presents three stable isotopes 24Mg, 25Mg and 26Mg with a natural abundance of 79%, 10%, and 11% respectively. It is due to their relatively large mass difference (~8% between 24Mg and 26Mg) that isotope fractionation leads to slight isotope amount ratio variations n(26Mg)/n(24Mg) in biological and geological samples. Traditionally, isotope amount ratios have been measured by mass spectrometric methods. However, drawbacks of these methods include the high costs for instruments and their operation, experienced operators and elaborate chromatographic sample preparation which are time-consuming. Recently, optical spectrometric methods have been proposed as faster and low-cost alternative for the analysis of isotope ratios of selected elements by means of high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) and laser ablation molecular isotopic spectrometry (LAMIS). For the determination of Mg isotope amount ratios, the molecular spectrum of the in-situ generated MgF and MgO molecules were studied. In the case of HR-CS-GFMAS, the absorption spectrum was recorded for MgF for the electronic transitions X 2Σ → A 2 Πi and X 2Σ → B 2Σ+ around wavelengths 358 nm and 268 nm respectively. In the case of LAMIS, it was studied the MgF molecule for the electronic transitions A 2Πi → X 2Σ as well as the MgO molecule for the electronic transition A 1Π+ → X 1Σ around 500 nm. The MgF and MgO spectra are composed by the linear combination of their isotopic components or isotopologues: 24MgF, 25MgF, and 26MgF for the MgF and 24MgO, 25MgO, and 26MgO for the MgO (F is monoisotopic, and the isotope composition of O is assumed as constant). By HR-CS-GFMAS the analysis of Mg was done by deconvolution of the MgF spectrum by a partial least square regression (PLS) calibrated with enriched isotope spikes. The isotope amount ratios in rock samples with and without matrix separation were analyzed. Resulting delta values were obtained with precisions ranging between 0.2-0.5 ‰. On the other hand, LAMIS allows the direct analysis of solid samples with the extended possibility of in-situ analysis. Main advantages, limitations, and scopes of both optical techniques are going to be discussed and compared with MC-ICP-MS.
Der Bunsen-Kirchhoff-Preis 2022 wurde am 23.06.2022 anlässlich der analytica conference in München an Dr. Carlos Abad verliehen - in Anerkennung seiner exzellenten Entwicklungen im Bereich der continuum source atomic absorption spectrometry (CS-AAS).
Dr. Carlos Abad ist ein herausragender Experte auf dem Gebiet der Atom- und molekularen Absorptionsspektrometrie. insbesondere trug er maßgeblich zur substanziellen Weiterentwicklung von Echelle-Spektrometern für die CS-AAS bei. So gelang es, einen quantitativen Zugang zu Elementen wie Bor, Chlor, Fluor und Schwefel, mittels AAS zu erreichen. Erstmals demonstriert Dr. Carlos Abad am Beispiel eines Zr-Modifier, dass durch die Zeitauflösung der eingesetzten Echelle-Systeme mechanistische Untersuchungen zur Wirkung des Modifiers im Graphitrohrofen möglich sind.
Besonders hervorzuheben sind seine Arbeiten zum Einsatz der CS-AAS für die Analyse von Isotopen, die eine Genauigkeit aufweist, welche an die der Multikollektor-induktiv gekoppelten Plasma-Massenspektrometrie (MC-ICP-MS) heranreicht. Damit ergeben sich völlig neue Einsatzmöglichkeiten für technologisch hochrelevante Applikationen, wie z.B. die Untersuchung der Alterung von Lithium-Batterien oder die Lithium-Analyse in Blutserum.
Is it a parmesan cheese from Italy? Who painted the Mona Lisa? The determination of the place of origin is essential for consumer protection, detection of falsifications, and also to bring justice.
All the tangible possess an isotopic fingerprint. However, current technologies are too expensive. We work on the development of fast and low-cost optical instruments and methods for isotope analysis.
Isotope analysis can be used to determine the age and provenance of geological samples. Modern techniques in optical spectrometry allow us a stand-off isotope analysis. This seminar will discuss how planetary science with the next Moon and Mars missions drive optical spectrometry into precise and accurate isotope analysis and how BAM will contribute.
Boron and Magnesium present two and three stable isotopes respectevely. It is due to their relatively large mass difference (~ 10%) that isotope fractionation leads to considerable isotope amount ratio variations in the nature. These have been used as a proof of provenance of mineral and biological samples, to estimate a contamination source and to the determination of geological processes by erosion or subduction. Additionally, boron is employed in the nuclear industry due to the capability of its isotope 10B to thermal-neutron capture and therefore 10B enriched boric acid solutions are used in the cooling system of thermonuclear facilities and in the alloying of steel and carbides for protective shielding. Traditionally, isotope ratio variations have been determined by mass spectroscopic methods.
Here an alternative faster and low cost method for isotope ratio determination is proposed: high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS). Isotope amount ratios have been determined by monitoring the absorption spectrum of boron monohydride (BH) for boron and Magnesium monofluoride (MgF) for magnesium in a graphite furnace HR-CS-MAS. Bands (0→0) and (1→1) were evaluated. Partial least square regression (PLS) for analysis of samples and reference materials were applied. For this, a spectral library with different isotopes ratios for PLS regression was built. Results obtained are metrologically compatible with those reported by mass spectrometric methods. Moreover, a precision and accuracy of the method of ± 0.5 ‰. This accuracy and precision is comparable with those obtained by thermal ionization mass spectrometry (TIMS) and multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) for boron isotope ratio measurements
Is it a parmesan cheese from Italy? Who painted the Mona Lisa? The determination of the place of origin is essential for consumer protection, detection of falsifications, and also to bring justice.
All the tangible possess an isotopic fingerprint. However, current technologies are too expensive. We work on the development of fast and low-cost optical instruments and methods for isotope analysis.
We propose an alternative faster and low-cost optical method for isotope analysis: high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS).
Stable isotope amount composition of X = Li, B, Mg, Ca and Sr were determined by monitoring the absorption spectra of their in situ generated mono-hydrides (XH) in graphite furnace HR-CS-MAS. Isotopes of boron (10B and 11B) were studied via their hydrides for the electronic transition X1Σ+ → A1Π (Fig. 1a). The spectrum of a given sample is a linear combination of the 10BH molecule and its isotopologue 11BH. Therefore, the isotopic composition of samples can be calculated by a partial least square regression (PLS). For this, a spectral library is built by using samples with known isotope composition. Results with an accuracy of 0.15 ‰ are metrologically compatible with those reported by mass spectrometric methods. Similar results are obtained for n isotope systems like Mg (24Mg, 25Mg, and 26Mg), where isotope shifts of their isotopologues can be resolved as shown in Fig.1b. The extension of this methodology to other elements like Li, Ca and Sr is discussed.
Magnesium is a major element in the hydrosphere and biosphere and plays important roles in (bio-) geochemical and physiological cycles. Mg has three stable isotopes, 24Mg, 25Mg and 26Mg. It is due to their relatively large mass difference (~8% between) that isotope fractionation leads to slight variations of isotope amount ratios in biological, environmental and geological samples. Traditionally, isotope amount ratios are measured by mass spectrometric methods. Their drawbacks include the high costs for instruments and their operation, experienced operators and elaborate time-consuming chromatographic sample preparation. Recently, an optical spectrometric method has been proposed as faster and low-cost alternative for the analysis of isotope ratios: high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS).
For the determination of Mg isotope ratios in selected rock reference materials, the high-resolution molecular absorption spectrum of in-situ generated MgF molecule was studied applying multivariate analysis and the results compared with MC-ICP-MS. Samples were dissolved by acid digestion and Mg isotopes analyzed with and without matrix. The absorption spectra were recorded for MgF for the electronic transition X 2Σ → B 2Σ+. The MgF spectrum is described as the linear combination of their isotopic components or isotopologues: 24MgF, 25MgF, and 26MgF. The isotope analysis was done by deconvolution of the MgF spectrum by partial least square regression (PLS). A PLS model was built and calibrated with enriched isotope spikes and certified reference materials. Spectra data was preprocessed by a derivate of second order and venetian blinds cross-validation was employed for finding the optimum latent variables. Finally, the model was refined by a genetic algorithm which identified the best subset of variables for a precise and accurate regression. Results are compatible with those obtained by MC-ICP-MS with an accuracy of ± 0.3‰ with uncertainties ranging between 0.02 to 0.6‰.
Isotope analysis can be used to determine the age and provenance of geological samples or to study dynamic systems like Li-ion batteries. Modern techniques in optical spectrometry allow us a fast and slow-cost isotope analysis. These techniques include high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS) and laser ablation molecular isotopic spectrometry. This seminar will discuss our recent work on precise and accurate isotope analysis of boron, magnesium, and lithium with geology, climate, and energy research applications.
Magnesium (Mg) is a major element in a range of silicate and carbonate minerals, the hydrosphere and biosphere and plays important roles in (bio-) geochemical and physiological cycles. Mg has three stable isotopes, 24Mg, 25Mg and 26Mg with natural abundances of 79 %, 10 %, and 11 %, respectively. It is due to their relatively large mass difference (~8% between 24Mg and 26Mg) that isotope fractionation leads to slight variations of isotope amount ratios n(26Mg)/n(24Mg) in biological, environmental and geological samples. Traditionally, isotope ratios are measured by mass spectrometric methods and isotope ratios are expressed as deviation from an internationally agreed upon material, i.e. the zero-point of the δ-value scale. Drawbacks of this method include the high costs for instruments and their operation, experienced operators and elaborate, time-consuming chromatographic sample preparation.
Recently, optical spectrometric methods have been proposed as faster and low-cost alternative for the analysis of isotope ratios of selected elements by means of high- resolution continuum source graphite furnace molecular absorption spectrometry (HR- CS-GFMAS) and laser ablation molecular isotopic spectrometry (LAMIS).
For the determination of Mg isotope amount ratios, the molecular spectrum of the in-situ generated MgF and MgO molecules were studied. In the case of HR-CS-GFMAS, the absorption spectrum was recorded for MgF for the electronic transitions X2Σ → A2Πi and X 2Σ → B2Σ+ around wavelengths 358 nm and 268 nm, respectively. In the case of LAMIS, we investigated the MgF molecule for the electronic transition A2Πi → X2Σ as well as the MgO molecule for the electronic transition A1Π+ → X1Σ around 500 nm. The MgF and MgO spectra are described by the linear combination of their isotopic components or isotopologues: 24MgF, 25MgF, and 26MgF for the MgF and 24MgO, 25MgO, and 26MgO for the MgO (F is monoisotopic, and the isotope composition of O is assumed as constant). By HR-CS-GFMAS the analysis of Mg was done by deconvolution of the MgF spectrum by partial least square regression (PLS) calibrated with enriched isotope spikes. Isotope amount ratios in rock samples with and without matrix separation were analyzed. Calculated δ-values were accurate and obtained with precisions ranging between 0.2 ‰ and 0.5 ‰ (1 SD, n = 10). On the other hand, LAMIS allows the direct analysis of solid samples with the extended possibility of in-situ analysis. Main advantages, limitations, and scopes of both optical techniques are going to be discussed and compared to MC-ICP-MS.
Mass spectrometric methods (MC-ICP-MS and TIMS) are without doubt the working horse of stable isotope analysis. However, drawbacks of these methods include the high costs for instruments and their operation, experienced operators and elaborate chromatographic sample preparation which are time consuming.
We propose a lower-cost and faster optical alternative for the analysis of isotope ratios of selected elements: high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS). Stable isotope amount compositions of boron (B) and magnesium (Mg) were determined based on the absorption spectra of in-situ generated mono-hydrides and halide (MH and MX) using graphite furnace HR-CS-MAS. The use of a modular simultaneous echelle spectrograph (MOSES) helps to find the maximal isotope shift in the diatomic molecular spectra produced in a graphite furnace by using isotopic spike solutions. Isotopes of boron (10B and 11B) were studied via their hydrides for the electronic transition X 1Σ+ → A 1Π. The spectrum of a given sample is a linear combination of the 10BH molecule and its isotopologue 11BH. Therefore, the isotopic composition of samples can be calculated by a partial least square regression (PLS). For this, a spectral library was built by using samples and spikes with known isotope composition. Boron isotope ratios measured by HR-CS-MAS are identical with those measured by mass spectrometric methods at the 0.15 ‰ level. Similar results were obtained for a multiple isotope system like Mg (24Mg, 25Mg, and 26Mg), where isotope shifts of their isotopologues can be resolved in the MgF molecule for the electronic transition X 2Σ → A 2 Πi. The extension of this methodology to other elements like Li, Ca, Cu, and Sr is discussed.
Mass spectrometric Methods MC-ICP-MS and TIMS) are without doubt the working horse of stable isotope analysis. However, drawbacks of these methods include the high costs for instruments and their operation, experienced operators and elaborate chromatographic sample preparation which are time consuming.
Optical spectrometric methods are proposed as faster and low-cost alternative for the analysis of isotope ratios of selected elements by means of high-resolution continuum source molecular absorption spectrometry (HR-CS-MAS) and laser ablation molecular isotopic spectrometry (LAMIS). First, stable isotope amount compositions of boron (B) and magnesium (Mg) were determined based on the absorption spectra of in-situ generated heteronuclear diatomic molecules (MH or MX) in graphite furnace HR-CS-MAS. The use of a modular simultaneous echelle spectrograph (MOSES) helps to find the maximal isotope shift in the diatomic molecular spectra produced in a graphite furnace by using isotopic spike solutions. Isotopes of boron (10B and 11B) were studied via their hydrides for the electronic transition X 1Σ+ → A 1Π. The spectrum of a given sample is a linear combination of the 10BH molecule and its isotopologue 11BH. Therefore, the isotopic composition of samples can be calculated by a partial least square regression (PLS). For this, a spectral library was built by using samples and spikes with known isotope composition. Boron isotope ratios measured by HR-CS-MAS are identical with those measured by mass spectrometric methods at the 0.15 ‰ level. Similar results were obtained for a multiple isotope system like Mg (24Mg, 25Mg, and 26Mg), where isotope shifts of their isotopologues can be resolved in the MgF molecule for the electronic transition X 2Σ → A 2 Πi. Finally, the application of molecular spectrometry via emission by LAMIS is compared and discussed.
Simultaneous multielemental analysis of crude oils by high-resolutions absorption spectrometry
(2019)
When crude oil arrives at a refinery it needs a lot of processing before it is suitable for cracking into lighter fractions. Sulfur has to be extracted to meet ultra-low sulfur legislation for most of the fuel grades, and desalination is a crucial process as chlorine within salts is corrosive to refinery equipment. Measuring the amounts of sulfur and chlorine within crude oil is the first step in a complex clean-up process.
Heavy metals, such as vanadium, nickel and iron need to be removed too. These metals can poison the catalyst used to crack the oil into lighter fractions. This is costly as it reduces the useful life of the catalyst. Like chlorine, heavy metals also have a corrosive effect on the plant. There is some evidence that the presence of some metals in the final product can reduce performance.
A fast determination of elements and size of suspended particles is vital for diagnosis and safeguard of refinery equipment. However, sample preparation for current analytical methods consumes precious time and lost particle size information.
High-resolution continuum source graphite furnace absorption spectrometry (HR-CS-GFAS) is proposed as a fast analytical method for elemental determination in crude oils and potentially for simultaneous multielement and particle size analysis. This HR-CS-GFAS instrumentation is coupled to a modular simultaneous echelle spectrometer (MOSES) and provides a full optical window with high resolution (from 180 to 900 nm with bandwidth λ/170,000). By using this set-up, it is possible to generate a multiparameter 3D spectral image (atomic and molecular lines, isotopic shift, atomization delay, and intensities). The generated spectral images can be analyzed by multivariate regressions for the elemental and particle size analysis. Additionally, if several atomic and molecular lines are simultaneously measured, they may be used in multi-energy calibration (MEC), a method based on the use of many wavelengths of the same absorbing/emitting entity to improve the accuracy in analytical atomic spectrometry. This MEC approach combined with multivariate image analysis allows the quantification of selected elements (Si, Al, Ni, Fe, V, S, and Cl) and overcomes matrix effects.
Advances and Applications of Molecular Absorption Spectrometry: from Non-Metals to Isotope Analysis
(2019)
The present work covers two main aspects of high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS), an analytical technique for elemental trace analysis.
First, a comprehensive mechanistic study of molecule formation in graphite furnaces is presented, which is a key step into the recovery of analytical signals. For this, the molecule formation of CaF was studied, which is used for the indirect analytical determination of fluorine in HR-CS-GFMAS. A zirconium coating catalyzes the CaF formation, and its structure was investigated. The kinetics of this reaction was established by monitoring its molecular spectrum at different atomisation temperatures. An Arrhenius plot showed a pseudo-first order reaction with respect to fluorine (n = 1). An intermediate state was isolated, and its structure was elucidated by spectroscopic methods: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XANES and EXAFS), and Raman microspectroscopy. Here a mechanism is proposed, where ZrO2 works as a heterogeneous catalyst: after a pyrolytic step, an intermediate state of ZrO(OCaF) is activated, and at higher temperatures, CaF(g) is released from the zirconium-coated graphite surface.
Second, analytical methods were developed by using HR-CS-MAS as detector for non-metals and isotope analysis. Therefore, the determination of organic absorbable chlorine in water, the quantification of fluorine in consume care products with declared perfluorinated ingredients, and the determination of sulfur content in crude oils were investigated. Finally, the high resolution of the instrumentation allows to measure isotopic shifts with high precision in some observed molecular spectra. Consequently, the molecular spectra of enriched isotopes of boron and magnesium were investigated, establishing so the potential of HR-CS-MAS for the accurate and precise determination of isotopic amount ratios.
Zusammenfassung
Die vorliegende Arbeit befasst sich mit zwei zentralen Aspekten der High-Resolution-Continuum-Source-Molekülabsorptionsspektrometrie mit Graphitrohrtechnik (HR-CS-GFMAS), einer Analysetechnik für elementare Spurenanalyse.
Der erste Teil der Arbeit umfasst eine mechanistische Studie zur Molekülbildung auf Graphitoberflächen. Dies ist ein wichtiger Schritt, um analytische Signale zu entdecken. Dazu wurde die Molekülbildung von CaF analysiert, welches für die indirekte, analytische Bestimmung von Fluor in HR-CS-GFMAS genutzt wird. Die CaF Bildung wurde mittels einer Beschichtung aus Zirconium katalysiert und deren Struktur analysiert. Die Kinetik dieser Reaktion wurde durch Beobachtung des jeweiligen Molekülspektrums bei verschiedenen Atomisierungstemperaturen beobachtet. Ein Arrheniusplot zeigte für Fluor (n = 1) eine Reaktion Pseudo-erster Ordnung. Ein Übergangszustand wurde über die mit Zirconium überzogene Grafitoberfläche isoliert und seine Struktur mittels spektroskopischer Methoden Energiedispersive Rasterelektronenmikroskopie / Röntgenspektroskopie (REM-EDX), Röntgenphoto¬elektronenspektroskopie (XPS), Röntgenabsorptionsspektroskopie (XAS) und Raman Spektroskopie untersucht. Auf Grundlage dieser Ergebnisse wird ein Mechanismus vorgeschlagen, bei dem ZrO2 als heterogener Katalysator fungiert; in Folge einer Pyrolysestufe wird ein Übergangszustand des ZrO(OCaF) aktiviert, welcher bei höheren Temperaturen CaF(g) an der Zirconium-Graphitoberfläche freisetzt.
Im zweiten Teil der Arbeit werden Analysemethoden entwickelt, in dem HR-CS-MAS als Detektor für Nichtmetalle und Isotopanalyse angewandt wird. Hierfür wurde organisch gebundenes Chlor im Wasser bestimmt, der Fluorgehalt in Pflegeprodukten mit perfluorierten Inhaltsstoffen quantifiziert und der Schwefelgehalt in Erdöl untersucht. Weiterhin ermöglicht die hohe Auflösung der Messgeräte eine präzise Bestimmung der Isotopenverschiebung einiger untersuchter Molekülspektren. Daher wurden die Molekülspektren angereicherter Bor- und Magnesiumisotope untersucht. Auf diese Weise wurde das Potential von HR-CS-MAS für die akkurate und präzise Bestimmung von Isotop-Mengenverhältnissen nachgewiesen.
An alternative method for lithium isotope analysis by using high-resolution atomic absorption spectrometry (HR-CS-AAS) is proposed herein. This method is based on monitoring the isotope shift of approximately 15 pm for the electronic transition 22P←22S at around the wavelength of 670.8 nm, which can be measured by state-of-the-art HR-CS-AAS. Isotope analysis can be used for (i) the traceable determination of Li concentration and (ii) isotope amount ratio analysis based on a combination of HR-CS-AAS and spectral data analysis by machine learning (ML).
In the first case, the Li spectra are described as the linear superposition of the contributions of the respective isotopes, each consisting of a spin-orbit doublet, which can be expressed as Gaussian components with constant spectral position and width and different relative intensity, reflecting the isotope ratio in the sample. Precision was further improved by using lanthanum as internal spectral standard. The procedure has been validated using human serum-certified reference materials. The results are metrologically comparable and compatible with the certified values.
In the second case, for isotope amount ratio analysis, a scalable tree boosting ML algorithm (XGBoost) was employed and calibrated using a set of samples with 6Li isotope amount fractions ranging from 0.06 to 0.99 mol mol−1. The training ML model was validated with certified reference materials. The procedure was applied to the isotope amount ratio determination of a set of stock chemicals and a BAM candidate reference material NMC111 (LiNi1/3Mn1/3Co1/3O2), a Li-battery cathode material. These determinations were compared with those obtained by MC-ICP-MS and found to be metrologically comparable and compatible. The residual bias was −1.8‰, and the precision obtained ranged from 1.9‰ to 6.2‰. This precision was sufficient to resolve naturally occurring variations. The NMC111 cathode candidate reference material was analyzed using high-resolution continuum source atomic absorption spectrometry with and without matrix purification to assess its suitability for technical applications. The results obtained were metrologically compatible with each other.
Glow discharge optical emission spectroscopy (GD-OES) is a technique for the analysis of solids such as metals, semiconductors, and ceramics. A low-pressure glow discharge plasma is applied in this system, which ‘sputters’ and promotes the sample atoms to a higher energy state. When the atoms return to their ground state, they emit light with characteristic wavelengths, which a spectrometer can detect. Thus, GD-OES combines the advantages of ICP-OES with solid sampling techniques, which enables it to determine the bulk elemental composition and depth profiles. However, direct solid sampling methods such as glow-discharge spectroscopy require reference materials for calibration due to the strong matrix effect.
Reference materials are essential when the accuracy and reliability of measurement results need to be guaranteed to generate confidence in the analysis. These materials are frequently used to determine measurement uncertainty, validate methods, suitability testing, and quality assurance. In addition, they guarantee that measurement results can be compared to recognized reference values. Unfortunately, the availability of certified reference materials suited to calibrate all elements in different matrix materials is limited. Therefore various calibration strategies and the preparation of traceable matrix-matched calibration standards will be discussed.
Machine learning is an essential component of the growing field of data science. Through statistical methods, algorithms are trained to make classifications or predictions, uncovering key insights within data mining projects. Therefore, it was tried in our work to combine GD-OES with machine learning strategies to establish a new and robust calibration model, which can be used to identify the elemental composition and concentration of metals from a single spectrum. For this purpose, copper reference materials from different manufacturers, which contain various impurity elements, were investigated using GD-OES. The obtained spectra information are evaluated with different algorithms (e.g., gradient boosting and artificial neural networks), and the results are compared and discussed in detail.
Hepcidin-25 has attracted much attention ever since its discovery in 2001. It is widely recognized that this peptide hormone plays a major role in the regulation of iron levels in mammals and can reveal important clinical information about several iron-related disorders. However, the development of a reliable assay to quantify hepcidin proved to be problematic and serum hepcidin-25 concentrations determined by various assays differ substantially. Challenges arise in the MS analysis of hepcidin due to the “sticky” character of the peptide and the lack of suitable standards.
With the aim to tackle the current difficulties in hepcidin quantification and improve the status of this promising biomarker in the clinical field, we developed a rapid and robust analytical strategy for the quantification of hepcidin-25 in human samples based on HPLC-MS/MS (QqQ) as a reference method candidate to be implemented in routine laboratories. The novelty of the method is the use of amino- and fluoro-silanized autosampler vials to reduce hepcidin interaction to laboratory glassware surfaces. Furthermore, we have investigated two sample preparation strategies and two chromatographic separation conditions where the use of acidic mobile phases was compared with a novel approach involving solvents at high pH containing 0.1% of ammonia. Both methods were carefully validated and applied to clinical samples in an intra-laboratory comparison of two LC-MS/MS methods using the same hepcidin-25 calibrators with very good correlation of the results.
Trialkoxysilane haben sich in den vergangenen Jahren als vielseitig einsetzbare Organosilane erwiesen. Die Einsatzgebiete erstrecken sich vom Witterungsschutz von Bauwerken über haftvermittelnde Eigenschaften in der Glasfaserindustrie, bei Dicht- und Klebstoffen, in Farben und Lacken bis hin zur Modifizierung von polymeren Werkstoffen.
Kommerzielle Benchtop-NMR-Spektrometer haben das Potential auch im Bereich der Silanchemie als Online-Methode zur Reaktionsüberwachung und für die Qualitätskontrolle eingesetzt zu werden. Interessante NMR-Kerne für die oben genanntem Produkte sind 1H und 29Si. In einer gemeinsamen Forschungskooperation zwischen EVONIK und BAM wurde anhand verschiedener Fallstudien die Anwendbarkeit der Niederfeld-NMR-Spektroskopie zur chemischen Analyse von Silanen evaluiert. Im Zuge der Fallstudien wurde gezeigt, wie Niederfeld-NMR-Spektroskopie die Möglichkeiten der Konzentrationsmessung auf neue Anwendungsgebiete erweitert, in denen bestehende Technologien wie z. B. NIR, Raman, UV/VIS, etc. mangels Referenzdaten nicht quantitativ eingesetzt werden können.
Fallstudie 1: Oligomerisierung
Eine Fallstudie setzte dazu an, den Hydrolyse- und Kondensationsverlauf mit einer geeigneten Online-NMR-Analytik zu beobachten, den Reaktionsfortschritt der Hydrolyse und Kondensation auf dieser Basis besser zu verstehen und zu optimieren. Zu diesem Zweck werden durch Zugabe von Wasser zunächst die Alkoxysubstituenten eines Trialkoxysilans hydrolysiert und entsprechende Silanole gebildet. Diese können dann über eine SiOH-Funktion an den zu modifizierenden Werkstoff anbinden und über weitere Silanolgruppen unter Ausbildung von Siloxaneinheiten vernetzen.
Fallstudie 2: Spaltung von cyclischen Silanverbindungen
In einer weiteren Fallstudie wurde die Kinetik der Aufspaltungen einer cyclischen Silanverbindung untersucht. Die Online-NMR-Analytik kam hierbei sowohl im Labor als auch in der industriellen Produktionsanlage zum Einsatz. Hierfür wurde eine vollständig automatisierte Einhausung verwendet, welche den Einsatz eines kommerziellen NMR-Spektrometers in explosionsgeschützten Bereichen ermöglicht.
Fallstudie 3: Qualitätskontrolle für Produktmischungen von Trialkoxysilanen
Für Produktmischungen eines Trialkoxysilans und weiteren Bestandteilen wie u. a. org. Stabilisatoren, Organozinnverbindungen, eines aromatischen Amins und org. Peroxide wurden quantitative 1H-Spektren akquiriert und eine automatische Auswertungsmethode basierend auf Indirect Hard Modeling (IHM) entwickelt. Für die Nebenkomponenten, deren Stoffmengenanteile bis zu 3 Mol-% betragen, wurden durch die zugrunde gelegte Methode typischerweise korrekte experimentelle Stoffmengenanteile gefunden, die weniger als 0,2 Mol-% vom Referenzwert abweichen.
Zusätzlich zu Methodenentwicklung, Miniaturisierung und Kopplungsverfahren zeigen sich die Hyperspektroskopie zusammen mit Imaging‐Verfahren, der Einzelmolekülnachweis und der Einsatz von 3‐D‐Druckern als neue Schwerpunkte. Hinzu kommen künstliche Intelligenz bei Sensoren, Bildgebungsverfahren und Prozesssteuerung sowie die Vernetzung von Analyse‐ und Laborgeräten. Trends und Forschungsthemen aus der analytischen Chemie, zusammengestellt von elf Autoren, koordiniert von Günter Gauglitz.
Carbamazepine (CBZ) and cetirizine (CTZ) are pharmaceutical drugs detected in the aquatic environment. However, the effects to marine invertebrates derived from the combination of these drugs with decreased pH conditions due to ocean acidification are poorly explored. This study investigated the biochemical parameters related to metabolic capacity and oxidative stress response and the transcription of genes related to the mode of action (MoA) of CBZ (1.0 μg/L) and CTZ (0.6 μg/L) in the clam Ruditapes philippinarum chronically exposed (28 days) to control (7.8) and low (7.5) pH conditions. The biochemical parameters applied were: the activity of electron transport system (indicator of organisms’ metabolic capacity); lipid peroxidation content (indicator of cell damage); total glutathione peroxidase activity (indicator of antioxidant defense). The transcription of genes related with drug neurotransmission and metabolism, cell defense and immunity and biomineralization was studied. No metabolic changes and oxidative stress was induced by the exposure to CBZ or CTZ at each pH level, but the transcription of several genes related with the MoA (neurotransmission, immunity and biomineralization) was altered by low pH, drug exposure and the combination of both stressors. In conclusion, it was shown that the interaction of drug exposure and low pH conditions can change bivalves’ sensitivity to drugs or alter drugs toxicity.
Der Vortrag wurde im Rahmen der Abschlusskonferenz des Forschungsschwerpunktes "Plastik in der Umwelt" des BMBF gehalten. Er fasst die Ergebnisse des Verbundprojektes RUSEKU zusammen. Es wurde die Herstellung verschiedener Testmaterialien für die Mikroplastik (MP) Analytik beschrieben. Im weiteren geht es um verschiedene Ansätze MP kostengünstig und schnell zu detektieren, z.B. mit Nahinfrarotspektroskopie. Nanoplastik konnte mit der Transmissionselektronenmikroskopie sichtbar gemacht werden. Für die praxisnahe Beprobung von Gewässern wurde die Fraktionierte Filtration entwickelt. Integrale Beprobungen können mit dem Sedimentationskasten erfolgen. Als Beispiele für die Beprobung realer Gewässer wurde das urbane Abwassersystem Kaiserslautern, Getränkewasser und Waschmaschinenwasser gezeigt.
Mikroplastik findet sich in Ozeanen, Seen, Flüssen und Bächen. Es kann in unserem Boden, in der Luft und sogar in Organismen nachgewiesen werden. Jedes Jahr werden weltweit Millionen Tonnen freigesetzt. Doch wo und wie landet Mikroplastik in der Umwelt? Und wie können wir diese winzigen Partikel nachweisen?
Detektion von Mikroplastik
(2022)
Im Verbundprojekt RUSEKU wurde die Probenahme von Wasserproben entscheidend weiterentwickelt. Wichtig ist hierbei zu gewährleisten, dass genügend Merkmalsträger in jeder Probe untersucht werden. Es muss daher eine für den Probenahmeort repräsentative Beprobung hinsichtlich des Wasservolumens in Abhängigkeit der Partikelanzahl gewährleistet sein.
Das Hauptaugenmerk lag im vorliegenden Projekt auf einer praxisnahen Beprobungsstrategie. Es wurden verschiedene Konzepte ausprobiert.
• Grundsätzlich hat sich gezeigt, dass eine Stichprobe eine Momentaufnahme des MP-Massengehaltes zeigt. Es wird eine hohe Statistik, also eine Vielzahl an Messungen am gleichen Probenahmeort, benötigt, um eine valide Aussage über den MP-Gehalt zu machen.
• Es zeigt sich, dass eine integrale Probenahme über mehrere Wochen mit dem SK routinemäßig möglich ist. Die erfassten MP-Massen sind reproduzierbar und robust.
• Die DFZ ist für Stichproben geeignet. Partikel < 50 µm werden eventuell unterschätzt
• Die fraktionierte Filtration kann für Stich- und Mischproben direkt im Feld genutzt werden. Fraktionen von 10 und 5 µm werden später im Labor Vakuum filtriert. Es erfolgt eine Fraktionierung der Probe mit Siebmaschenweiten von 1000, 500, 100, 50, 10 und 5 µm.
• Die fraktionierte Filtration kann auch anschließend an die Beprobung mit dem SK zur Anwendung kommen. Wird die mit dem SK gewonnene Wasserprobe fraktioniert filtriert, kann neben einem MP-Gesamtgehalt auch eine Einschätzung über die Partikelgrößen gewonnen werden.
• Für Wässer mit geringen Partikelzahlen wurde ein Messfiltertiegel entwickelt. Dieser hat eine Maschenweite von 6 µm. Seine Anwendung kann mögliche Verluste beim Transferieren vom Probenahmetool zum Messgefäß und mögliche Kontaminationen reduzieren.
Die Optimierung der Probenahmestrategie wurde durch Modellversuche und Simulationen unterstützt. Modellversuche zum Sinkverhalten und Simulationen von MP in realen Gewässern verdeutlichten das komplexe Verhalten der Partikel. Es konnte gezeigt werden, dass Partikel ab einer bestimmten Größe (und kleiner) bei genügend starker Turbulenz sich in der Wassersäule unabhängig von ihrer Dichte verhalten und so auch MP mit kleiner Dichte (z.B. PE) in der gesamten Wassersäule zu finden sind. Es konnte mit dem TEM die Existenz von NP gezeigt werden.
Ein wesentlicher Aspekt des RUSEKU Projektes war die Beprobung realer Kompartimente. Beprobt wurde neben Oberflächengewässern, das urbane Abwassersystem der Stadt Kaiserslautern, Waschmaschinenabwasser und Flaschenwasser.
• In Oberflächengewässern wurde hauptsächlich PE gefunden. Je nach Probe und Gewässer konnten auch PP, PS, PET, PA, SBR und Acrylate nachgewiesen werden.
• Im urbanen Abwassersystem der Stadt Kaiserslautern konnte an allen Probenahmestandorten MP nachgewiesen werden. Es wurde hauptsächlich PE, neben geringeren Mengen an PP, PS und SBR gefunden. Nach einem Regenereignis war der SBR Anteil deutlich erhöht.
• Die Beprobung eines realen Wäschepostens, bestehend aus T-Shirts und Hemden mit PA/CO oder PES/CO Mischgewebe, zeigte einen PA- und PES-Austrag im Waschwasser. Der überwiegende Teil der detektierten Fasern ist aber auf Baumwolle zurückzuführen. Reine gravimetrische Messungen zur Detektion von MP führen zu einer starken Überschätzung.
• In Flaschenwasser (PET-Flaschen) konnte MP detektiert werden. PET wurde nur im stillen Mineralwasser, nicht in Mineralwasser mit Kohlensäure gefunden werden. Teilweise wurde auch das MP-Material des Verschlusses im Wasser detektiert.
• Für Luftproben konnte ein Aufbau zur größenselektiven Beprobung getestet werden.
Neben der Probenahme hat das Projekt auch gezeigt, dass die TED-GC/MS geeignet für die MP-Detektion im Routinebetrieb ist. Die TED-GC/MS konnte weiter optimiert werden. Es wurden MP-Massen bestimmt.
Im Projekt wurden erste realitätsnahe Referenzmaterialien für die MP Detektion hergestellt. Die Herstellung von realitätsnahen Polymeren in ausreichender Homogenität und Menge hat sich als große Herausforderung herausgestellt.
Monitoring von Mikroplastik
(2021)
In recent years, thermoextraction/desorption-gas chromatography/mass spectrometry (TED-GC/MS) has been developed as a rapid detection method for the determination of microplastics (MP) mass contents in numerous environmentally relevant matrices and, in particular, for the measurement of polymers in water samples without time-consuming sample preparation. The TED-GC/MS method was applied to investigate a typical European municipal wastewater system for possible MP masses. Such investigations are important in view of the recent revision of the Urban Wastewater Treatment Directive. Four different representative sampling sites were selected: greywater (domestic wastewater without toilet), combined sewer, and influent and effluent of a wastewater treatment plant (WWTP). All samples were collected by fractional filtration. Filtration was carried out over mesh sizes of 500, 100, 50, and in some cases, 5 µm. Polyethylene (PE), polypropylene (PP), and polystyrene (PS) were detected in all samples, with the PE fraction dominating in all cases. Styrene-butadiene rubber which serves as an indication of tire abrasion, was only found in the influent of the WWTP. The highest MP mass contents were found in the combined sewer, so MP can become a source of pollution during heavy rain events when the capacity limits of the effluent are reached, and the polluted effluent is released uncontrolled into the environment. Based on the studies, MP retention from the WWTP could be estimated to be approximately 96%. Few trends in polymer type or mass contents were detected within the different fractions of the samples or when comparing samples to each other.
In this breakout session first, an introduction is given on the planning and organisation of an inter-laboratory comparison (ILC) under the pre-standardisation plattform VAMAS within the newly formed technical working area TWA 45 Micro and Nano Plastics in the Environment. An update with the ILCs on micro- and nanoplastic performed so far is also given. In the third part, the requirements for a reference materials are presented. The needs from the different H2020 micro- and nanoplastic projects are collected and compiled in an ILC matrix for joint activities as the next steps.
Metallic nanoparticles (NPs) are currently applied in a variety of consumer products and are also attractive for medical applications. With their widespread use, the potential for human exposure to NPs — either intended or unintended — is increasing. Therefore, many studies have evaluated the toxicity and transport mechanism of NPs. In comparison with two-dimensional cultured cells, multicellular spheroids (MCS) look promising to be used as a three-dimensional cellular model, having unique advantages in nanoparticle studies due to the fact that interactions with excreted extracellular matrix can be investigated. Fibroblast cells are one of the most important cell systems to express a microenvironment by excreting an abundant extracellular matrix. For bioimaging laser ablation inductively coupled-plasma mass spectrometry (LA-ICP-MS) is used in this investigation to study the interaction of metallic NPs with MCS for multi-element detection offering a wide dynamic range. As a mass spectrometer we have applied a time-of-flight (TOF) instrument for (quasi-) simultaneous detection of all isotopes of elements of interest.
The aim of this study is to investigate the localization of silver (Ag) NPs exposed to fibroblast MCSs by means of LA-ICP-TOF-MS. In addition, for demonstrating elemental microscopy we chose phosphorous (31P) and iron (56Fe) to visualize regions of enriched extracellular matrix and single cells, respectively. In this presentation, we show that exposed Ag NPs are highly accumulated at the same position of single cells in an outer rim of fibroblast MCSs.
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.
Imaging of Eu doped very small iron oxide nanoparticle in atherosclerotic plaques via LA-ICP-MS
(2018)
Atherosclerotic lesions can be visualized by magnetic resonance imaging (MRI) using very small iron oxide nanoparticles (VSOP). VSOP accumulate in atherosclerotic plaques and thus serve as an atherosclerosis probe. The aim of this project was to image the distribution of europium doped VSOP (Eu-VSOP) by laser ablation ICP-MS in histological thin cuts of the aortic root region of ApoE knockout mouse model that is rich in atherosclerotic plaques. In addition, it was investigated whether VSOP accumulation in the plaques correlates with other biomarkers of inflammation for example macrophages and altered endothelium to assess whether it correlates with instability or vulnerability of the plaque regions. For this purpose, antibodies were labeled with various lanthanide elements and correlated with the Eu-VSOP distribution using LA-ICP-MS in a multiplex measurement mode.
Imaging of Eu doped very small iron oxide nanoparticle in atherosclerotic plaques via LA ICP-MS
(2018)
Atherosclerotic lesions can be visualized by magnetic resonance imaging (MRI) using very small iron oxide nanoparticles (VSOP). VSOP accumulate in atherosclerotic plaques and thus serve as an atherosclerosis probe.
The aim of this project was to image the distribution of europium doped VSOP (Eu-VSOP) by laser ablation ICP-MS in histological thin cuts of the aortic root region of ApoE knockout mouse model that is rich in atherosclerotic plaques. In addition, it was investigated whether VSOP accumulation in the plaques correlates with other biomarkers of inflammation for example macrophages and altered endothelium to assess whether it correlates with instability or vulnerability of the plaque regions. For this purpose, antibodies were labeled with various lanthanide elements and correlated with the Eu-VSOP distribution using LA-ICP-MS in a multiplex measurement mode.
A possible correlation of reactive oxygen species (ROS) with endogenous iron or Eu-VSOP can also be detected by LA-ICP-MS. For this purpose, ROS-specific antibodies were also labeled with lanthanides.
Imaging of Eu doped very small iron oxide nanoparticle in atherosclerotic plaques via LA-ICP-MS
(2018)
Atherosclerotic lesions can be visualized by magnetic resonance imaging (MRI) using very small iron oxide nanoparticles (VSOP). VSOP accumulate in atherosclerotic plaques and thus serve as an atherosclerosis probe.
The aim of this project was to image the distribution of europium doped VSOP (Eu-VSOP) by laser ablation ICP-MS in histological thin cuts of the aortic root region of ApoE knockout mouse model that is rich in atherosclerotic plaques. In addition, it was investigated whether VSOP accumulation in the plaques correlates with other biomarkers of inflammation for example macrophages and altered endothelium to assess whether it correlates with instability or vulnerability of the plaque regions. For this purpose, antibodies were labeled with various lanthanide elements and correlated with the Eu-VSOP distribution using LA-ICP-MS in a multiplex measurement mode.
A possible correlation of reactive nitrogen species (RNS) with endogenous iron or Eu-VSOP can also be detected by LA-ICP-MS. For this purpose, RNS-specific antibodies were also labeled with lanthanides.
Atherosklerotische Läsionen können durch Magnetresonanztomographie (MRT) unter Verwendung von sehr kleinen Eisenoxidnanopartikeln (VSOP) sichtbar gemacht werden. VSOP akkumulieren in atherosklerotischen Plaques und dienen somit als Atherosklerosesonde.
Das Ziel dieses Projektes war die Abbildung der Verteilung von Europium-dotierten VSOP (Eu-VSOP) durch Laserablation ICP-MS in histologischen Dünnschnitten der Aortenwurzelregion des ApoE-Knockout-Mausmodells, das reich an atherosklerotischen Plaques ist. Darüber hinaus wurde untersucht, ob die VSOP-Akkumulation in den Plaques mit anderen Biomarkern der Entzündung wie Makrophagen und verändertem Endothel korreliert. Somit wäre eine Beurteilung, ob es sich hierbei um instabile bzw. vulnerable Plaque-Regionen handelt möglich. Zu diesem Zweck wurden Antikörper mit verschiedenen Lanthaniden markiert und mit der Eu-VSOP-Verteilung unter Verwendung von LA-ICP-MS in einem Multiplex-Messmodus korreliert.
Eine mögliche Korrelation von reaktiven Stickstoffspezies (RNS) mit endogenem Eisen oder Eu-VSOP kann ebenfalls durch LA-ICP-MS nachgewiesen werden. Zu diesem Zweck wurden RNS-spezifische Antikörper auch mit Lanthaniden markiert.
Due to their toxicity and widespread application for mining and industrial purposes, cyanides are ranking among the most important inorganic pollutants which should be tested and monitored not only in the aquatic environment, but also in soils and soil-like materials. Reference materials of soils with relevant contents of cyanide to ensure reliable test results of laboratories are rare today.
New certified reference material (CRM) BAM-U116/CGL306 “Cyanide in soil” was produced within a framework of cooperation between Central Geological Laboratory (CGL) of Mongolia and Federal Institute for Materials Research and Testing (BAM) of Germany in 2013-2017.
The CRM BAM-U116/CGL306 represents a mixture of a sandy soil collected from a contaminated former gasworks area in the Berlin region (Germany) and an unpolluted sandy soil from Nalaikh region (Mongolia). The bulk candidate material for this reference material was prepared at CGL CRM Laboratory exclusively destined to the preparation of reference materials and equipped with modern technical equipment. Homogeneity, stability and shelf life were studied in full compliance with ISO Guide 35. The CRM was evaluated as sufficiently homogeneous. Statistical evaluation of certification analysis was performed using software packages SoftCRM and ProLab Plus. Certified value of total cyanide of the CRM is 12.0 mg/kg and expanded uncertainty was assigned as 0.8 mg/kg.
The intended purpose of this material is the verification of analytical results obtained for the mass fraction of total cyanide in soils and soil-like materials applying the standardized procedure ISO 11262:2011. As any reference material, it can also be used for routine performance checks (quality control charts) or validation studies.
This poster presents the focused ion beam preparation methodologies developed within the framework of the EU funded EURAMET project ADVENT (Advanced Energy-Saving Technology).
It summarises the key breakthroughs achieved for various in situ investigation techniques, e.g. in situ experiments at the Synchrotron facility BESSY II (IR-SNOM and XRS), TEM and SMM instrumentation.
The created experimental devices from diverse thin-film semiconductor materials paved the way to dynamic structural studies bearing the potential to determine nanoscale correlations between strain and electric fields and, moreover, for the fundamental development of new in situ capabilities.
qNMR - The handbook
(2023)
Quantitative NMR (qNMR) has been around for a long time, but also has great potential to solve future problems in any quantitative analysis. As a primary method, it differs fundamentally from chromatographic methods: it is better described as a quantum mechanical balance. Succesful implementation of qNMR requires certain attention to detail. "qNMR - the handbook" is intended to be a guide for analysts to help understand the fundamental principles of NMR and the significant points relating to its implementation for quantitation. Regulatory considerations of qNMR adoption are explained. NMR fundamentals are explained to provide understanding. Together with many useful examples, the book is a compelling addition to the laboratory's reference library, providing all the tools that any practitioner should know to successfully implement qNMR.
The authors are qNMR pioneers and come from a variety of backgrounds including business, government and academia.
High polarity analyte(s) in aqueous media: determination of L-PFOA and L-PFOS in ground water
(2022)
The CCQM-K156 comparison was coordinated by TUBITAK UME on behalf of the Organic Analysis Working Group (OAWG) of the Comité Consultatif pour la Quantité de Matière (CCQM) for National Measurement Institutes (NMIs) and Designated Institutes (DIs) which provide measurement services in organic analysis under the 'Comité International des Poids et Mesures' Mutual Recognition Arrangement (CIPM MRA).
Perfluoro alkyl substances (PFAS) such as PFOS and PFOA have been used in numerous industrial applications and products. Because of their high stability and resistance to biodegradation, atmospheric photooxidation, direct photolysis and hydrolysis, they are extremely persistent in the environment. The European Union (EU) Water Framework Directive lists PFOS as a priority hazardous substance that poses a significant risk to the aquatic environment. The use of PFOS-containing Aqueous Film-Forming Foams (AFFFs) has been banned since June 2011 in the EU. As relatively water-soluble, effectively non-degradable compounds, PFOS and PFOA migrate to ground water. They are not removed in the conventional drinking water treatment, and therefore cause health risks in polluted areas. The EU Drinking Water Directive and the European Commission has proposed a limit value of 100 ng/L for the sum of 20 PFAS, including PFOS and PFOA.
This study provides the means for assessing measurement capabilities for determination of high polarity measurands in a procedure that requires extraction, clean-up, analytical separation and detection. Successful participation in CCQM-K156 demonstrates measurement capabilities in determining mass fraction of organic compounds, with a molecular mass of 200 g/mol to 700 g/mol, having high polarity pKow -2, in a mass fraction range from 0.5 ng/kg to 500 ng/kg in aqueous media.
Nine NMIs and DIs participated in the CCQM-K156 key comparison. Seven institutes reported their results. SPE was applied in the sample pre-treatment and LC-MS was applied for detection. All participating laboratories applied isotope dilution mass spectrometry (IDMS) techniques for quantification. Participants established the metrological traceability of their results using certified reference materials (CRMs) from NMIs with stated traceability; where commercially available high purity materials were used the purity was determined in-house. The CCQM-K156 results for L-PFOA and L-PFOS range from 2.75 ng/kg to 5.50 ng/kg with a % RSD of 19.5 % for L-PFOA and from 2.04 ng/kg to 4.45 ng/kg with a % RSD of 21.3 % for L-PFOS. The KCRV was assigned using a Hierarchical Bayesian Random Effects Model (HB REM) estimator from the values reported by six of the participants. One participant result of L-PFOS and one result of L-PFOA were excluded from the KCRV for technical reasons. The KCRV was 4.9 ng/kg ± 0.4 ng/kg for L-PFOA and 3.8 ng/kg ± 0.4 ng/kg for L-PFOS. The six institutes that were included in the assignment of consensus KCRV all agreed within their standard uncertainties.
To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.
The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
Nearly all disease processes are associated with variations of components of the extracellular matrix (ECM) that are typically observed during the development of inflammation. This concerns for example proteoglycans and their associated glycosaminoglycans (GAG), which have been shown to bind to cationic metal imaging probes due to their strong complexing activity. The complexing activity largely depends on the degree of GAG sulfation and/or carboxylation as well as on the GAG isomericity. In this central project, we investigate GAG structures from inflammatory disorders (namely cardiovascular diseases, inflammatory intestinal diseases and neuroinflammation) provided by researchers of the Collaborative Research Center at the molecular disaccharidic level using chromatographic and mass spectrometric methods. In parallel, the spatial localization and quantification of metal-based imaging probes are evaluated by LA-ICP-MS imaging.
Thermal Destruction of PFAS
(2023)
Thermal treatment processes are currently the only full-scale option for thedestruction of per- and polyfluoroalkyl substances (PFAS) in large waste streams. While all organic molecules including PFAS are susceptible to thermal destruction, their decomposition rates are controlled by process variables such as temperature, reaction atmosphere, and residence time. Concerns exist about the formation of products of incomplete destruction and their emission from hazardous waste incinerators. This talk will summarize the current stateof-the-art of thermal PFAS destruction, identify research needs, and showcase future research designed to address critical knowledge gaps.
Modular production involving benchtop NMR Current Application Examples Driven by Digitalization
(2022)
The demand for increasing product diversity in the chemical and pharmaceutical industry calls for new production processes that enable greater flexibility. Therefore, plants are needed which can be adapted to new processes in a fast manner and be scaled up and down easily to volatile market demands. Modular production techniques in combination with advanced process analytical technology (PAT) are considered as a promising solution able to fulfil these requirements.
The success and acceptance of modular concepts in both new and existing plants is dependent of its reliability, easy applicability, and standardization. In recent past, enormous efforts were made to overcome existing barriers in a superordinate level, e.g. DEXPI, ENPRO, or MTP naming just a few. Here, we’d like to present a few, more hands-on, application examples which are shown in Figure 1 aiming to increase process flexibility and applicability.
Soil acts as a final sink for pollutants. Microplastics from different sources such as plastic mulching, littering, compost, sewage sludge, sedimentary deposition, and tyre abrasion are expected to be found in soil. However, representative and comprehensive information is missing on the sources, transport, and fate. Therefore, a reliable analysis method for microplastics in soils needs to be developed.
The presented work describes the development of a procedure for microplastics analysis in soils. A representative sampling based on the on-site conditions and a sample preparation method was established and comprised of a drying step, the separation of microplastic particles > 1 mm, and a density separation for particles < 1 mm. The detection of the large microplastic particles (> 1 mm) was conducted with Attenuated Total Reflection - Fourier Transform infrared Spectroscopy (ATR-FTIR) , while Thermal Extraction Desorption - Gas Chromatography / Mass Spectrometry (TED-GC/MS) was applied for particles < 1 mm, gaining information on the type of polymer and mass fraction. Based on the established method, 14 environmental soil samples ? with different exposure of microplastics from agriculture, industrial sites, roads, and floods were investigated.
Due to the arbitrary microplastic particle distribution among the samples for large microplastics, it was reasoned that the found particles were unrepresentative. In contrast, microplastic particles < 1 mm were discovered in a high mass in soil samples exposed to plastic mulching or fertilization with sewage sludge or compost (0 – 115 mg/kg). On average, microplastic contents detected in soil samples taken from a construction site and an inner-city lake were higher (13 – 238 mg/kg). As expected, microplastic content in soil sampled in proximity to roads was more pronounced in the upper soil layers. In contrast, very remote sampling sites, expectably uncontaminated, did not lead to the detection of microplastic regarding to thermoanalytical detection method.
In a proof of concept experiment several in vivo and in vitro ecotoxicological tests were applied to evaluate the effect of microplastics (tyre abrasion, polystyrene containing hexabromocyclododecane) in natural soils. In summary, while no effects of the examined probes could be detected on higher levels of biological organization after exposures to earthworm E. andrei, significant changes in several oxidative stress related biomarkers were observed.
Die zunehmenden Nachweise von Kunststoffen in verschiedenen Umweltmedien erfahren in den letzten Jahren weltweit ein zunehmendes wissenschaftliches, gesellschaftliches und politisches Interesse. Besondere Aufmerksamkeit erfahren Kunststoffpartikel von 1-1.000 µm, sogenanntes Mikroplastik. Es wurde mittlerweile in Wasser, Böden, Luft und Biota nachgewiesen. Obwohl die Wirkungen auf die natürlichen Umweltfunktionen noch unklar sind und kontrovers diskutiert werden, ist allein durch die ubiquitäre Präsenz eine systematische Erfassung von Eintragsquellen und Verbleib der Partikel über alle Umweltmedien notwendig, um Maßnahmen zur Reduktion der Einträge zu veranlassen.
Für eine zuverlässige Erfassung sind medienübergreifende Verfahren zu entwickeln, welche die drei analytischen Schritte, Probennahme, Probenaufbereitung und Detektion beinhalten. Die Verfahren adressieren unterschiedliche Zielgruppen, welche verschiedene analytische Informationen fordern. Für die akademische Bewertung werden Verfahren mit hohem analytischen Aufwand favorisiert, welche möglichst detaillierte Information über Partikelsorte, -größe, -zahl und -oberflächenbeschaffenheit geben. Im Gegensatz dazu, fordern Anwender aus der Praxis schnelle und einfache Monitoring Verfahren, welche die Bestimmung eines Massengehaltes, bzw. eines Grenzwertes zulassen. Allen ist gemeinsam, dass ein hoher interdisziplinärer Anspruch besteht, der sowohl technische Voraussetzungen zur repräsentativen Probennahme und die Limitationen von Detektionsverfahren berücksichtigt, als auch die Fachkompetenz von Biologen, Umweltwissenschaften, Analytiker und Polymerwissenschaftler einschließt.
Verfahren zum Mikroplastiknachweis müssen auch verschieden Proben mit sehr unterschiedlichen Gehalten an natürlicher Matrix gerecht werden. So müssen allein für Wasser Verfahren entwickelt werden, die Mikroplastik verschiedener Form (sphärische Partikel, komplexe Bruchstücke, Fasern) aus Medien mit sehr variablen Partikelanteil (u.a. Trinkwasser, Oberflächenwasser, Abwasser) repräsentativ erfassen, sowie schnell und kostengünstig sind – einschließlich der notwendigen Probenaufbereitung. Die jeweiligen Detektionsverfahren müssen z.B. einzelne Partikel oder integrale Gehalte über drei Dekadenklassen für thermoplastische und insbesondere auch elastomere Partikelsorten erfassen können.
The accumulation of plastics leaked into the environment achieve a high perception in the last years. It is uncontroversial that often an uncontrolled, high consumption of plastic products and a poor waste management resulted in plastic findings all over in the environment. However, less is known about the relevant pathways and fate of plastic in the environment. Especially plastic fragments smaller 5 mmm, so called microplastics, achieve a high attention, because their amount and risks arising from these fragments are still unknown. The basic mechanisms of plastic or more precise, of different polymer degradation processes are often not considered, resulting in unrealistic statements.
For generation of fundamental understanding of this problem we developed in the last years a fast thermoanalytical method for identification and mass quantification of microplastics in complex samples. The presentation will also give a short introduction about polymer degradation.
The occurrence of microplastic particles (MP) in nearly each environmental compartment but especially in water is well documented in an increasing amount of publication within the last few years. However, a comprehensive understanding of MP occurrence, sources and pathways in the environment as well as effects of MP on the environment is still unclear. Many of the studies are not compatible, because they used different sampling, sample preparation and detection techniques, resulting in a very broad variation and very different dimension of archived results. Hence a useful avoiding strategy for reduction the MP entry in the environment is not possible. Furthermore, the existing methods are often very time consuming, need user knowledge and labour force, which is often not acceptable for the routine monitoring of an action or sanction.
The call for harmonised methods become loud and louder and promising efforts are done in this area. However, the scientific discussion is often focus on advantages and disadvantages of detection tools and sample preparation, less initiative is given to the sampling strategy. That is a pity, because every environmental scientist knows, a good analytical result depend on a good sampling strategy.
The sampling of water seems on the first view easy because the sampling process include already an up concentration of the MP by means of sieves and filters. However, this filtering of water is often limited by filter cake on the sieves, consisting of high amount of natural particular matter. Hence often a small water volume is filtered, which will not own a representative amount of trait carriers or complex sieves cascades are used, which need a high technical equipment.
Recently we presented a fast thermoanalytical method for the detection of polymers fractions in water samples. This method, thermo-extraction desorption gas chromatography mass spectrometry (TED-GC-MS) can analyse MP in water filtrates without sample preparations within 2-3 hours. Advantageous is the additional analysis of rubber particles from tires beside the MP. In order to come even faster we now start to develop new sampling strategies, which should be use for different water systems. It is intended to reduce the effort in the field and to elongate times for sampling to obtain a representatives result without random effects.
In the present presentation we will show first result using a sedimentation box for sampling of MP from surface water. Advantages and disadvantages will be discussed and comparison to data from conventional fractionated filtration will be given.
In the interest of exploring their potential in the field of single particle analysis, a Microdroplet Generator (MDG) was coupled to an ICP-ToF-MS. Isotopic Dilution Analysis was also incorporated for the size determination of three different Platinum nanoparticles samples (50, 63 and 70 nm). The performance of the technique was validated by comparison to traditional size characterization techniques (sp-ICP-ToF-MS, TEM), while the robustness of the technique was proven by incorporating NaCl in the samples’ matrix, up to 100 mg/L.
Ultrasound echo is a widely used NDT technique for determining the internal geometry of structures. Reverse-time migration (RTM) has been recently introduced to NDT applications, as an imaging method for ultrasound data, to overcome some of the limitations (e.g. imaging steeply dipping reflector) experienced by the Synthetic Aperture Focusing Technique (SAFT), the most commonly used imaging algorithm for these measurements.
The standard implementation of RTM also experiences some drawbacks caused by its imaging condition, which is based on the zero-lag of the cross-correlation between source and receiver wavefields and generates high-amplitude low-frequency artifacts. Three alternative imaging conditions, developed for seismic data applications, were tested for their ability to provide better images than the standard cross-correlation: illumination compensation, deconvolution and wavefield decomposition. A polyamide specimen was chosen for the simulation of a synthetic experiment and for real data acquisition. The migrations of both synthetic and real data were performed with the software Madagascar. The illumination imaging condition was able to reduce the low-frequency noise and had a good performance in terms of computing time. The deconvolution improved the resolution in the synthetic tests, but did not showed such benefit for the real experiments. Finally, as for the wavefield decomposition, although it presented some advantages in terms of attenuating the low-frequency noise and some unwanted reflections, it was not able to image the internal structure of the polyamide as well as the cross-correlation did. Suggestions on how to improve the cost-effectiveness of the implementation of the deconvolution and wavefield decomposition were presented, as well as possible investigations that could be carried out in the future, in order to obtain better results with those two imaging conditions.
Type-I pyrethroids are frequently used for disinfection purposes against insects such as adult mosquitoes, or diseases carried by insects, like Malaria or Zika in cabins of airplanes on long-distance flights especially from tropical destinations. This treatment is mandatory at various airports but compliance with the rules is difficult to test for. Moreover, if improperly used, these compounds can entail negative health effects for crews and passengers.
The detection of the pyrethroids will be achieved thanks to an antibody-gated indicator delivery system (gAID) utilizing monoclonal antibodies and hybrid sensory nanoparticles. After the interaction of the pyrethroid with the gAID, the liberated indicator (dye) will be detected. Since only few analyte molecules are necessary for pore opening yet release a large number of dyes, the system shows intrinsic signal amplification.
The device system to be developed has to be so simple that chemically untrained personnel, such as ground or cabin crew, can use it and obtain a result in a reasonably short period of time, e.g., ≤5 min. The need for high accuracy and sufficient sensitivity, established at 0.001 g m–2, is a critical requirement and imposes another significant challenge since this value is beyond current LFTs reported in the literature for pesticide detection to date.
In order to achieve the selectivity and sensitivity required by the test itself, and to avoid cross reactivity with other type I pyrethroids, the production of a monoclonal antibody for both Permethrin and Phenontrin is necessary. The synthesis of the two hapten molecules and the subsequent immunization with different immunogens represent the first goal of the work.
An immunohistochemical method is described to visualize the distribution of metallothioneins 1/2 (MT 1/2) and metallothionein 3 (MT 3) in human ocular tissue. It is making use of (a) antibodies conjugated to gold nanoclusters (AuNCs) acting as labels, and (b) laser ablation (LA) coupled to inductively coupled plasma – mass spectrometry (ICP-MS). Water-soluble fluorescent AuNCs (with an average size of 2.7 nm) were synthesized and then conjugated to antibody by carbodiimide coupling. The surface of the modified AuNCs was then blocked with hydroxylamine to avoid nonspecific interactions with biological tissue. Immunoassays for MT 1/2 and MT 3 in ocular tissue sections (5 μm thick) from two post mortem human donors were performed. Imaging studies were then performed by fluorescence using confocal microscopy, and LA-ICP-MS was performed in the retina to measure the signal for gold. Signal amplification by the >500 gold atoms in each nanocluster allowed the antigens (MT 1/2 and MT 3) to be imaged by LA-ICP-MS using a laser spot size as small as 4 μm. The image patterns found in retina are in good agreement with those obtained by conventional fluorescence immunohistochemistry which was used as an established reference method.
Ionische Flüssigkeiten als neuartige Sensorbeschichtung für coulometrische Spurenfeuchtesensoren
(2018)
Die Arbeit präsentiert erste Messungen mit coulometrischen Sensoren, die mit einer ionischen Flüssigkeit beschichtet sind. Diese Sensoren werden in der Industrie verwendet, um die Spurenfeuchte in unterschiedlichen Gasen zu messen. Normalerweise erfolgt eine Beschichtung der Sensoren mit Phosphorpentoxid und dessen Hydrolyseprodukte. In dieser Arbeit wurde stattdessen eine hygroskopische ionische Flüssigkeit benutzt. Die generierte Gasfeuchte für die Untersuchungen betrug bezogen auf die Frostpunkttemperatur -80 °C bis -30 °C, was gleichbedeutend mit einem Wasserdampf-Stoffmengenanteil von 0,5 μmol·mol-1 bis 376 μmol·mol-1 ist. Zusätzlich zu der Messung mit coulometrischen Sensoren erfolgte eine Referenzmessung der Gasfeuchte mittels eines Taupunkthygrometers. Erste Ergebnisse haben gezeigt, dass es möglich ist mit dieser Art der Beschichtung unterschiedliche Gasfeuchten zu messen. Aber es ergaben sich trotz gleicher Feuchte unterschiedliche Signalintensitäten bei den benutzen Sensoren und es zeigte sich eine Drift des Sensorsignales.
Planar coulometric sensors were investigated in humidified synthetic air at various absolute gas pressures, i. e. 2 bar, 5, bar, 10 bar, and 15 bar. Humidified gas flow at adjusted gas pressure was split into two flows, one passed a coulometric sensor and the other one passed a reference hygrometer after decompression. Both signals were recorded and then compared after calculation of resulting frost point temperature. Calculation is based on a calibration function obtained at ambient pressure. Comparison showed that an increasing pressure resulted in a higher derivation between sensor signal (calculated frost point temperature) and reference frost point temperature. At an absolute pressure of 2 bar the differences were minor in consideration of the uncertainty, however at 15 bar the differences were 6.77 K. Nevertheless, it was possible to measure the gas humidity at higher pressure with coulometric trace humidity sensors.
Die Spurenfeuchte ist eine wichtige Messgröße bei der Qualitätsbeurteilung von technischen und medizinischen Gasen und muss daher zuverlässig gemessen werden. Der Spurenbereich ist definiert durch einen Wasserdampf-Stoffmengenanteil kleiner als 2600 µmol/mol bzw. einer Frostpunkttemperatur kleiner -10 °C. Eine geeignete Methode für die kontinuierliche Spurenfeuchtemessung stellt das Elektrolyseverfahren bzw. coulometrische Messprinzip dar. Bei diesem Prinzip strömt ein feuchtes Gas über eine hygroskopische Phosphorpentoxid-Schicht, welche kontinuierlich Wasserdampf absorbiert. Durch das Anlegen einer Zersetzungsspannung wird das absorbierte Wasser elektrolysiert und der resultierende Elektrolysestrom korreliert zum Feuchtegehalt im Gas. Neben dem Einfluss von unterschiedlichen Gasen auf das Messverfahren, wurde der Einfluss der Druckfeuchte im Druckbereich von 2 bis 15 bar untersucht. Des Weiteren wurde eine neuartige Sensorbeschichtung basierend auf einer ionischen Flüssigkeit getestet und es wurde ein Prototyp für die abgestufte Bestimmung der Wasseraktivität und der Materialfeuchte aufgebaut.
Planar coulometric sensors were investigated in humidified synthetic air at various absolute gas pressures, i. e. 2 bar, 5, bar, 10 bar, and 15 bar. Humidified gas flow at adjusted gas pressure was split into two flows, one passed a coulometric sensor and the other one passed a reference hygrometer after decompression. Both signals were recorded and then compared after calculation of resulting frost point temperature. Calculation is based on a calibration function obtained at ambient pressure. Comparison showed that an increasing pressure resulted in a higher derivation between sensor signal (calculated frost point temperature) and reference frost point temperature. At an absolute pressure of 2 bar the differences were minor in consideration of the uncertainty, however at 15 bar the differences were 6.77 K. Nevertheless, it was possible to measure the gas humidity at higher pressure with coulometric trace humidity sensors.
Ionische Flüssigkeiten als neuartige Sensorbeschichtung für coulometrische Spurenfeuchtesensoren
(2018)
Die Arbeit präsentiert erste Messungen mit coulometrischen Sensoren, die mit einer ionischen Flüssigkeit beschichtet sind. Diese Sensoren werden in der Industrie verwendet, um die Spurenfeuchte in unterschiedlichen Gasen zu messen. Normalerweise erfolgt eine Beschichtung der Sensoren mit Phosphorpentoxid und dessen Hydrolyseprodukte. In dieser Arbeit wurde stattdessen eine hygroskopische ionische Flüssigkeit benutzt. Die generierte Gasfeuchte für die Untersuchungen betrug bezogen auf die Frostpunkttemperatur -80 °C bis -30 °C, was gleichbedeutend mit einem Wasserdampf-Stoffmengenanteil von 0,5 μmol·mol-1 bis 376 μmol·mol-1 ist. Zusätzlich zu der Messung mit coulometrischen Sensoren erfolgte eine Referenzmessung der Gasfeuchte mittels eines Taupunkthygrometers. Erste Ergebnisse haben gezeigt, dass es möglich ist mit dieser Art der Beschichtung unterschiedliche Gasfeuchten zu messen. Aber es ergaben sich trotz gleicher Feuchte unterschiedliche Signalintensitäten bei den benutzen Sensoren und es zeigte sich eine Drift des Sensorsignales.
Wasserzeichen und Papierstrukturen können einen wesentlichen Beitrag bei der Analyse von Kunstobjekten auf Papier darstellen. Ausgangspunkt hierfür bildet die korrekte Dokumentation mit entsprechender Bildaufnahme und der richtigen Erfassung und Interpretation der Phänomene. An Fallbeispielen aus Forschungsprojekten zu niederländischen Zeichnungen am Kupferstich-Kabinett Dresden und der Grafischen Sammlung Weimar sollen die Möglichkeiten der Papier- und Wasserzeichenforschung als historische Hilfswissenschaft demonstriert werden. Dieser Abendvortrag dient zugleich als Einführung in die Technologie der (Hand-)Papierherstellung, Wasserzeichenerfassung und –recherche.
With the latest ICP-MS technology - ICP-ToF (time of flight)-MS - it is possible to analyze the multi-element fingerprint of individual cells. The interface between material and environmental analysis thus receives special attention, e.g. when considering corrosion processes. Microbiologically influenced corrosion (MIC) is highly unpredictable due to the diversity of microbial communities involved. The development of the MIC-specific ICP-ToF-MS analytical method presented here at the single cell level, in combination with the investigation of steel-MIC interactions, contributes significantly to progress in instrumental MIC analysis and will enable clarification of the processes taking place.
The supplied document shows the basis of a four minutes lightning talk.
ICP-ToF (Flugzeitanalysator, engl. time of flight)-MS ermöglicht den Multielement Fingerabdruck einzelner Zellen (single cell) zu analysieren. Die single cell-ICP-ToF-MS kommt bei dem vorgestellten Poster bei der Analyse von Archaeen, die an mikrobiell beeinflusster Korrosion (engl. microbiologically influenced corrosion, MIC) von Stahl eine Rolle spielen, zum Einsatz. Mittels sc-ICP-ToF-MS wird die mögliche Aufnahme von einzelnen Elementen aus dem jeweiligen Stahl untersucht – die erhaltenen Informationen fließen zukünftig in die Aufklärung zugrunde liegender Mechanismen sowie Entwicklung möglicher Materialschutzkonzepte ein. Die Arbeiten Verknüpfen moderne Methoden der Analytical Sciences mit Materialien.
ICP-ToF (time of flight) MS enables the analysis of the multi-element fingerprint of single cells. The single cell ICP-ToF-MS is used in the presented poster for the analysis of archaea involved in microbiologically influenced corrosion (MIC) of steel. By means of sc-ICP-ToF-MS, the possible uptake of individual elements from the respective steel is investigated - the information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts. The work combines modern methods of analytical sciences with materials.
The latest ICP-MS technology - ICP-ToF (time of flight)-MS – enables the analysis of the multi-element fingerprint of individual cells. The interface between material and environmental analysis thus receives special attention, e.g., when considering corrosion processes. Microbiologically influenced corrosion (MIC) is a highly unpredictable phenomenon due to the influence of the environment, microbial communities involved and the respective electron source. However, the interaction pathway between cells and the metal surface remains unclear. The development of the MIC-specific ICP-ToF-MS analytical method presented here at the single cell level, in combination with the investigation of steel-MIC interactions, contributes significantly to progress in instrumental MIC analysis and will enable clarification of the processes taking place. For this, a MIC-specific staining procedure was developed. It allows the analysis of archaea at a single cell level and provides information about the interaction of the cells with the staining agent which is extremely scarce compared to other well characterized organisms. Additionally, the single cell ICP-ToF-MS is used for the analysis of archaea involved in MIC of steel. Hence, the possible uptake of individual elements from different steel samples is investigated - the information obtained will be used in the future to elucidate underlying mechanisms and develop possible material protection concepts, thus combining modern methods of analytical sciences with materials.
Up to now, different analytical methods for single cell analysis exist focusing on key features such as size, shape, morphology and elemental composition. The combination of the latest ICP-MS techniques - ICP-ToF-MS - together with the latest developments in the field of sample delivery - micro droplet generator (MDG) – will allow a Deep insight into the composition and size of cells.
Microbiologically influenced corrosion (MIC) is an oxidation of metals affected by the presence or activity (or both) of microorganisms e.g. Shewanella Putrefaciens in biofilms on the surface of the corroding material. As this can happen for example in the soil on iron pipes of water pipes, in oil tanks or on steel sheet piling, there is great interest in MIC research, not only from various industrial sectors, but also from the environmental aspect.
Eine umfangreich ausgestaltete Trinkwasseraufbereitung als Multibarrieren-System ist notwendig, wenn das Rohwasser direkt aus Fließgewässern entnommen wird (z. B. für das Mülheimer Verfahren). Eine der Barrieren wird, als gezielte Behandlungs- oder Sicherheitsstufe, oft als Filter mit granulierter Aktivkohle (GAK-Filter) realisiert. Ihre Standzeit kann bei geringer Wasserbelastung (DOC < 2 mg/L), z. B. bei der Landeswasserversorgung Langenau, bis zu 5 Jahre betragen. Bei Rohwasser mit höherem Organikgehalt (DOC > 7 mg/L), wie bei der Nordwasser in Rostock, wird hingegen mindestens alle drei Jahre die GAK in den Filterkolonnen ausgetauscht.
Die Rest-Adsorptionskapazität der GAK kann durch verschiedene Verfahren abgeschätzt werden, ist aber nach wie vor Gegenstand aktueller Forschung. Die weitergehende Charakterisierung der beladenen GAK kann hierbei helfen.
Auf dem Poster sollen erste Ergebnisse zu den in Langenau und Rostock eingesetzten Aktivkohlen präsentiert werden. Hierzu wurden die frischen und nach unterschiedlichen Laufzeiten beladenen GAK untersucht. Die Zusammensetzung der Anorganik und der adsorbierten Organik, welche mittels Zersetzungs¬gasanalyse charakterisiert wurde, zeigt deutliche Unterschiede. Bspw. nimmt der Calcium-Gehalt der GAK in Langenau kontinuierlich zu, wohingegen dieser in den Proben aus Rostock mit zunehmender Laufzeit zurückgeht. Umgekehrt verhält es sich mit der Organik: Die GAK aus Rostock zeigen Hinweise auf biologische Besiedelung, während diese in Langenau trotz längerer Filterlaufzeit auszubleiben scheint.
Solutions of organic analytes of known mass fraction are typically used to calibrate the measurement processes used to determine these compounds in matrix samples. Appropriate value assignments and uncertainty calculations for calibration solutions are critical for accurate measurements. Evidence of successful participation in formal, relevant international comparisons is needed to document measurement capability claims (CMCs) made by national metrology institutes (NMIs) and designated institutes (DIs). To enable NMIs and DIs to update or establish their claims, in 2015 the Organic Analysis Working Group (OAWG) sponsored CCQM-K131 "Low-Polarity Analytes in a Multicomponent Organic Solution: Polycyclic Aromatic Hydrocarbons (PAHs) in Acetonitrile".
Polycyclic aromatic hydrocarbons (PAHs) result from combustion sources and are ubiquitous in environmental samples. The PAH congeners, benz[a]anthracene (BaA), benzo[a]pyrene (BaP), and naphthalene (Nap) were selected as the target analytes for CCQM-K131. These targets span the volatility range of PAHs found in environmental samples and include potentially problematic chromatographic separations. Nineteen NMIs participated in CCQM-K131. The consensus summary mass fractions for the three PAHs are in the range of (5 to 25) μg/g with relative standard deviations of (2.5 to 3.5) %.
Successful participation in CCQM-K131 demonstrates the following measurement capabilities in determining mass fraction of organic compounds of moderate to insignificant volatility, molar mass of 100 g/mol up to 500 g/mol, and polarity pKow < −2 in a multicomponent organic solution ranging in mass fraction from 100 ng/g to 100 μg/g: (1) value assignment of primary reference standards (if in-house purity assessment carried out), (2) value assignment of single and/or multi-component organic solutions, and (3) separation and quantification using gas chromatography or liquid chromatography.
Vergleichende Darstellung SARS-CoV-2-spezifischer Nanobodys aus unterschiedlichen Wirtsorganismen
(2021)
Aufgrund der anhaltenden COVID-19-Pandemie werden neutralisierende Therapeutika benötigt. Eine Möglichkeit zur Behandlung stellt die Verwendung monoklonaler Anti-SARS-CoV-2-Immun-globuline dar. Ihre Produktion in Säugetierzellen ist jedoch schwer skalierbar, um den weltweiten Bedarf zu decken. VHH-Antikörper, auch Nanobodys genannt, bieten hierfür eine Alternative, da sie eine hohe Temperaturstabilität aufweisen und eine kostengünstige Produktion in prokaryotischen Wirtsorganismen ermöglichen.
Therapeutic monoclonal antibodies are the fastest-growing group of biological agents which generated a yearly turnover of USD 210 billion in 2022 and whose sales are expected to grow by 10% annually over the next 10 years. With steadily increasing market importance, analytical methods for reliable quantification of therapeutic antibodies also become more and more relevant. Liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) has become the main technology for antibody quantification. This approach, however, requires enzymatic digestion of the intact protein into peptides, for which a wide range of different protocols exists that often lead to different results depending on the digestion procedure or trypsin variants used. In particular, the amount and type of detergents added for protein unfolding prior to digestion is known to create significant bias in measurement results. The overall goal of the presented project is the application of novel thermostable and surface-functionalized trypsin particles for improved antibody digestion. Specifically, a trypsin-variant described in the literature exhibiting increased activity and thermal stability above 80°C, will be examined. The application of this enzyme should allow to perform digestion at elevated temperatures where the protein is naturally unfolding thereby increasing enzyme accessibility without the need for detergents. Furthermore, we will immobilize the thermostable trypsin onto the surface to further enhance enzyme stability, prevent self-digestion, and enable separation of trypsin from target peptides before LC–MS/MS analysis. As an immobilization platform, cheap and non-porous corundum particles will be used as these show high chemical stability and low levels of interaction of matrix proteins with the functionalized surface. adsorption. In a multidisciplinary collaboration with the SALSA Photonics Lab, we will investigate the characteristics of covalent enzyme binding and unspecific peptide binding using an interface-sensitive analytical tool, vibrational sum-frequency generation (VSFG) spectroscopy. The insights gained will not only lead to new competencies in peptide and enzyme surface analysis using VSFG spectroscopy in SALSA but will also significantly contribute to optimizing antibody quantification.
Contamination of the environment with antibiotics is of great concern as it promotes the evolution of antimicrobial resistances. In case of amoxicillin (AMX) in the aquatic environment, further risk arises from hydrolysis products (HPs) which can cause allergy. To assess these risks, a comprehensive investigation and understanding of the degradation of AMX is necessary. We investigated the hydrolysis rate of AMX in different types of water as well as the influence of temperature and irradiation. The content of the heavy metal ions copper and zinc was found to be crucial for the hydrolysis rate of AMX and stability of HPs. Eventually, a new degradation pathway for AMX could be elaborated and confirmed by tandem mass spectrometry (LC-MS/MS).
The contamination of drinking water with pharmaceuticals represents a severe health risk. In order to monitor the drinking water quality continuously and enable quick countermeasures in case of contamination, novel sensors are required. Here, immunoanalytical methods based on the binding of the analyte to highly selective antibodies can be helpful. In this work, magnetic bead-based immunoassays (MBBAs) have been developed for the detection of two relevant contaminants of drinking water: diclofenac (DCF) and amoxicillin (AMX). In case of the latter, not only the parent drug is of interest in the risk assessment but also its hydrolysis products (HPs). In a comprehensive study, the influence of external factors and intrinsic properties of the water on the rate of hydrolysis was investigated. As the hydrolysis of AMX further impacts the recognition by the antibody, a strategy to analyze samples with unknown hydrolysis degree of AMX was established employing the enzyme β-lactamase in sample preparation. For both analytes, the MBBAs enable the fast quantification with results obtained in less than one hour which represents a major improvement over conventional immunoassays like the enzyme-linked immunosorbent assay (ELISA). Compared to the respective ELISAs with the same antibodies, the MBBAs further exhibit improved analytical parameters such as a broader measurement range and lower limits of detection. Due to the magnetic properties of the beads that serve as a platform for the assays, they are suitable for the mobile and automated detection at the point-of-care. An integrated diagnostic system was designed in which electrochemical detection with chronoamperometry on a microfluidic chip allows for further miniaturization of the system to enable monitoring of the drinking water quality online in water supply pipes at waterworks.