Chemische Charakterisierung und Spurenanalytik
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Eingeladener Vortrag
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In 2019 over 30 000 people were killed or injured by explosions caused by explosives like TNT, PETN, HMX and RDX. Therefore, highly sensitive assays for the detection of TNT are needed. In this study we compared two commercially available TNT antibodies: A1.1.1 and EW75C with a highly optimized indirect competitive ELISA based on a BSA-TNA conjugate. As a result, a precision profile for both antibodies was determined with a LOD of 170 pmol L-1 for the clone A1.1.1 and a LOD of 3,2 nmol L-1 for the clone EW75C. The measurements showed that the clone A1.1.1 is a highly sensitive antibody for the detection of TNT while the clone EW75C does show medium performance at most.
In the cross-reactivity characterization of both antibodies many substances, closely related to the structure of TNT were tested. Both antibodies showed strong cross reactivity with trinitroaniline and trinitrobenzene. For the clone A1.1.1, which is known to originate from immunization of mice with an TNP-glycine-KLH conjugate, this has to be expected. Interestingly the clone EW75C, which was not characterized yet, showed similar behavior. This suggests a TNA-conjugate as immunogen for the EW75C antibody as well. None of both antibodies showed cross-reactions to the high explosives PETN, HMX and RDX. Also, the cross-reactions of nitro musks with the antibodies were investigated. Despite their prohibition, nitro musks are still used in Asia especially and are particularly popular in India. The overall superior clone A1.1.1 showed a significant cross-reactivity to musk ambrette. For practical reasons the influence of musk ambrette on this assay when used in natural environment should be investigated.
In further experiments, the highly sensitive TNT antibody A1.1.1 was digested with papain to obtain monovalent Fab-fragments. Due to its high stability against the digestion, a custom protocol for the IgG1 subclass of mice, to which the clone A1.1.1 belongs, was developed, resulting in a quantitative digestion of the intact antibody to Fab fragments. The success of the digestion was determined with MALDI-TOF-MS and SDS-PAGE. It was shown that this protocol worked for many different antibodies of IgG1 subclass as well.
Metal-containing nanoparticles (NP) can be characterized with inductively coupled plasma mass spectrometers (ICP-MS) in terms of their size and number concentration by using the single-particle mode of the instrument (spICP-MS). The accuracy of measurement depends on the setup, operational conditions of the instrument and specific parameters that are set by the user. The transport efficiency of the ICP-MS is crucial for the quantification of the NP and usually requires a reference material with homogenous size distribution and a known particle number concentration.
Currently, NP reference materials are available for only a few metals and in limited sizes. If particles are characterized without a reference standard, the results of both size and particle number may be biased. Therefore, a dual-inlet Setup for characterizing nanoparticles with spICP-MS was developed to overcome this problem. This setup is based on a conventional introduction system consisting of a pneumatic nebulizer (PN) for nanoparticle solutions and a microdroplet Generator (μDG) for ionic calibration solutions. A new and flexible interface was developed to facilitate the coupling of μDG, PN and the ICP-MS system. The interface consists of available laboratory components and allows for the calibration, nanoparticle (NP) characterization and cleaning of the arrangement, while the ICP-MS instrument is still running.
Three independent analysis modes are available for determining particle size and number concentration. Each mode is based on a different calibration principle.
While mode I (counting) and mode III (μDG) are known from the literature, mode II (sensitivity), is used to determine the transport efficiency by inorganic ionic Standard solutions only. It is independent of NP reference materials. The μDG based inlet system described here guarantees superior analyte sensitivities and, therefore, lower detection limits (LOD). The size dependent LODs achieved are less than 15 nm for all NP (Au, Ag, CeO2) investigated.
The goal of this work is to identify the optimal operating input for a lithiation reaction that is performed in a highly innovative pilot scale continuous flow chemical plant in an industrial environment, taking into account the process and safety constraints. The main challenge is to identify the optimum operation in the absence of information about the reaction mechanism and the reaction kinetics. We employ an iterative real-time optimization scheme called modifier adaptation with quadratic approximation (MAWQA) to identify the plant optimum in the presence of plant-model mismatch and measurement noise. A novel NMR PAT-sensor is used to measure the concentration of the reactants and of the product at the reactor outlet. The experiment results demonstrate the capabilities of the iterative optimization using the MAWQA algorithm in driving a complex real plant to an economically optimal operating point in the presence of plant-model mismatch and of process and measurement uncertainties.
Abstract: Since it is unknown for many applications, which PFASs are used and how they enter the environment, target analysis-based methods reach their limits. The two most frequently used sum parameters are the adsorbable organically bound fluorine (AOF) and the extractable organically bound fluorine (EOF). Both can be quantified using either combustion ion chromatography (CIC) or high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). Here we provide an insight on the advantageous and disadvantageous of both sum parameters and both detection methods. Our study is based on the analysis of surface water samples. Next to total fluorine (TF) analysis, AOF and EOF were determined as well as CIC and HR-CS-GFMAS are compared and results are comparatively discussed. Fluorine mass balancing revealed that, the AOF/TF proportion was higher than the EOF/TF proportion. The AOF made up 0.14–0.81% of TF and the EOF 0.04–0.28% of TF. Although, organically bound fluorine represents only a small portion of TF, PFASs are of worldwide concern, because of their extreme persistence and their bioaccumulation potential. The EOF-HR-CS-GFMAS method turned out to be more precise and sensitive than the AOF-CIC method and is a promising tool for future monitoring studies/routine analysis of PFASs in the environment.
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.
The demonstration of competency and equivalence for the assessment of levels of contaminants and nutrients in primary foodstuffs is a priority within the 10-year strategy for the OAWG Track A core comparisons. The measurements are core challenges for reference material producers and providers of calibration Services. This key comparison related to low polarity analytes in a high fat, low protein, low carbohydrate food matrix and Benzo[a]pyrene in edible oil was the model System selected to align with this class within the OAWG strategy. 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). 16 National Metrology Institutions participated in the Track A Key Comparison CCQM-K146 Low-Polarity Analyte in high fat food: Benzo[a]pyrene in Olive Oil. Participants were requested to evaluate the mass fractions, expressed in µg/kg, of Benzo[a]pyrene in the olive oil material. The KCRV was determined from the results of all NMIs/DIs participating in the key comparison that used appropriately validated methods with demonstrated metrological traceability. Different methods such as liquid-liquid extraction, GPC and SPE were applied in the sample pretreatment and HPLC-FLD, HPLC-MS/MS, and GC-MS or GC-MS/MS were applied for detection by the participants. The mass fractions for BaP were in the range of (1.78 to 3.09) µg/kg with Standard uncertainties of (0.026 to 0.54) µg/kg, with corresponding relative Standard uncertainties from 0.9% to 21%. Five labs withdrew their result from the Statistical evaluation of the KCRV for technical reasons. One lab was excluded from the KCRV evaluation, as they did not meet the CIPM metrological traceability requirements. A Hierarchical Bayes option was selected for the KCRV value, which was determined as 2.74 µg/kg with a Standard uncertainty of 0.03 µg/kg. The 10 institutes those were included in the calculation of the consensus KCRV all agreed within their Standard uncertainties. Successful participation in CCQM-K146 demonstrates the measurement capabilities in determining mass fraction of organic compounds, with molecular mass of 100 g/mol to 500 g/mol, having low polarity pKow < -2, in mass fraction range from 0.1 µg/kg to 1000 µg/kg in a high fat, low protein, low carbohydrate food matrix.
Mit der Novellierung der Bundes-Bodenschutz- und Altlastenverordnung (BBodSchV) (am 6.11.2020 im Bundesratsverfahren beschlossen) werden Regelungen zum Auf- und Einbringen von Bodenmaterial außerhalb der durchwurzelbaren Bodenschicht aufgenommen (sogenannte Verfüllungen). Ziel des Vorhabens war es, durch die Auswertung vorhandener und durchzuführender Untersuchungen eine Einstufung von Bodenmaterialien (jährlich fallen weit über 100 Mio. Tonnen davon an) für bestimmte Verwertungswege vornehmen zu können. Es sollte herausgefunden werden, ob Veränderungen hinsichtlich des Verwertungspotentials nachgewiesen werden können.
Basis für die Durchführung und Bewertung waren die neuen Regelungen (hier insbesondere die Untersuchung mit einem Wasser/Feststoffverhältnis von 2:1, neue nationale und europäische Elutions- und Untersuchungsverfahren) der novellierten BBodSchV. Der Fokus lag dabei auf den polyzyklischen aromatischen Kohlenwasserstoffen (PAK) sowie ausgewählte anorganische Stoffe (Schwermetalle und Anionen) unter der Berücksichtigung unterschiedlicher Bodenmaterialien zur Verwertung.
Dabei handelte es sich um:
- Böden aus urban geprägten Gebieten,
- Oberböden aus dem Straßenrandbereich in Form von Bankettschälgut,
- Baggergut aus Gewässern mit Verdacht auf eine Kontamination,
- Bergematerial (Mischung von Abraum- und Bodenmaterial),
- Auenböden mit vermuteten Verunreinigungen aus Industrie und Gewerbe.
Anhand der vorgelegten Ergebnisse kann nun eine Versachlichung der Diskussion um Ressorcenschutz vs. Schadlosigkeit der Verwertung erfolgen. Sie zeigen für die untersuchten Stoffe, dass bei einer Einführung der §§ 6-8 Novelle BBodSchV mit einer Erhöhung der Verwertungsquote für Bodenmaterial gerechnet werden kann. Eine Erhöhung des Deponievolumens ist somit nicht zu befürchten. Neben den ermittelten Daten konnten Grundlagen für die Überarbeitung verschiedener DIN-Normen für Bodenuntersuchungen erarbeitet werden.
In this investigation, two conventional peristaltic pumps are compared with a new pump based on the “easy click” principle using a simultaneous ICP-AES instrument with standard operating conditions. It is found that the figures of merit achieved are quite comparable for all three pumps. Relative standard deviations (RSDs) range between 0.2% and 1.8%, and limits of detection as low as 0.1 μg/L have been achieved , demonstrating that the easy click principle of the new pump does not compromise the analytical figures of merit.
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.