Analytische Chemie
Filtern
Dokumenttyp
- Vortrag (45) (entfernen)
Referierte Publikation
- nein (45) (entfernen)
Schlagworte
- Traceability (19)
- Metrology (18)
- Absolute isotope ratio (13)
- Uncertainty (8)
- Isotope ratio (7)
- CCQM (5)
- Isotope reference material (4)
- Copper (3)
- Delta value (3)
- Isotope amount ratio (3)
- Isotope delta value (3)
- Isotope fractionation (3)
- Reference material (3)
- Triple isotope fractionation (3)
- CMC (2)
- Cement (2)
- Delta scale (2)
- Isotope dilution mass spectrometry (2)
- Measurement uncertainty (2)
- Metrology in chemistry (2)
- Purity (2)
- Purity assessment (2)
- metrology (2)
- traceability (2)
- Alzheimer disease (1)
- Archaeology (1)
- Archaeometry (1)
- Atomic weight (1)
- Atomic weights (1)
- Biodiesel fuel (1)
- Blank characterization (1)
- Boron isotopes (1)
- Calibration (1)
- Certification (1)
- Cheese (1)
- Circular economy (1)
- Comparability (1)
- Comparison (1)
- Conventional isotope ratio (1)
- Conventional isotope ratios (1)
- Counting detector (1)
- Curse tablets (1)
- Degree of equivalence (1)
- Delta values (1)
- Dementia (1)
- Detector deadtime (1)
- Dual mode detector (1)
- EURAMET (1)
- Emissionen (1)
- Fundamental science (1)
- Gravimtric isotope mixtures (1)
- Gypsum (1)
- Heavy metals (1)
- Human serum (1)
- ICP-MS (1)
- ICPMS (1)
- IDMS (1)
- Impurities (1)
- Interferences (1)
- Iron (1)
- Isotope delta (1)
- Isotope mixtures (1)
- Isotope purification (1)
- Isotope reference materials (1)
- Lead isotopes (1)
- Mangesium (1)
- Mass spectrometry (1)
- Matrix separation (1)
- Measurement space (1)
- Metal sublimation (1)
- Metrology in Chemistry (1)
- Molar mass (1)
- Noise (1)
- Optimization (1)
- PGE (1)
- Plant metabolism (1)
- Primary method of measurement (1)
- Provenance (1)
- Purity determination (1)
- Quality system (1)
- Re-evaluation (1)
- SI traceability (1)
- Silicon (1)
- Silver artefacts (1)
- Soil (1)
- Standard addition (1)
- Sulfur (1)
- Synthetic isotope mixtures (1)
- TCE (1)
- Terminology (1)
- Tetramethylammonium hydroxide (1)
- Transferrin (1)
- Zinc (1)
- key comparison (1)
- purity (1)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (45)
Sr isotope ratio analysis
(2023)
Pb isotope ratio analysis
(2023)
Detector deadtime
(2023)
Isotope Ratio Analysis
(2023)
Introduction: The influence of copper, iron and zinc concentrations on the formation of ß-amyloid plaques and neurofibrillary tangles in Alzheimer’s disease (AD) is widely discussed in the community. The results from human and animal studies so far are mixed with some studies showing a correlation and others not. From a number of studies, it is known that disease state and isotopic composition of essential elements can be coupled.
Aim: The aim of the study was to identify changes in element content and isotopic composition in two transgenic mouse models used in AD research compared to their genetic WT relatives and to establish whether element content and isotopic signature between different laboratories is comparable.
Methods: ß-amyloid (5xFAD) and tau overexpressing (L66) mice together with their matching wild-types were bred at dedicated facilities in accordance with the European Communities Council Directive (63/2010/EU). Serum and brain were sampled after sacrifice and the samples distributed among the participants of the study. The tissues were acid digested for total element determination and high-precision isotope ratio determination. Element content was determined by either sector-field or quadrupole-based inductively coupled plasma mass spectrometry (ICPMS). For the determination of isotope ratios multi-collector ICPMS was used.
Results: Total copper content was significantly higher for L66 and their matched WT compared to 5xFAD and WT. Brains of L66 mice contained more Fe in brain than their WT, Zn and Cu were not significantly different between L66 and WT. Whereas 5xFAD mice had a slightly lower Cu and slightly higher Zn concentration in brain compared to WT. The isotopic signature in brain of L66 mice for Fe was different from their controls, whereas Zn isotope ratios were influenced in 5xFAD mice compared to their WT . The Cu isotopic ratio did not seem to be influenced in either strain. In serum, the shifts were less pronounced.
Conclusion: Even though neither Tau-protein nor amyloid precursor protein are known to be metal-dependent / -containing proteins, the overexpression of both influences the Fe, Cu and Zn metabolism in brain and to some extent also in serum as can be seen not only using total element determination but probably more clearly studying the isotopic signature of Fe, Cu and Zn.
This presentation provides a short introduction to the Commission on Isotopic Abundances and Atomic Weights (CIAAW). It describes the role of the Commission and provides an insight into its work and the corresponding principal tasks. Finally, it provides the reader with the latest achievements and with the most recent publications.
The reference method for obtaining absolute isotope ratios still is the isotope mixture approach. Due the huge efforts required the full isotope mixture approach is applied only by a few institutes worldwide. To enable an IRWG key comparison with a sufficiently large number of participants a proposal for absolute cu isotope ratios is presented where participants will be provided with the enriched isotopes, the isotope mixtures and the samples. In parallel a pilot study will be organized where alternative approaches for obtaining absolute Cu isotope ratios can be applied.
IRWG strategy update
(2023)
Determination of absolute (SI‐traceable) isotope ratios: The use of Gravimetric Isotope Mixtures
(2023)
The presentation is brief overview on how to use gravimetric isotope mixtures to determine SI traceable isotope ratios. There is no mass spectrometer on earth that directly measures isotope ratios. Mass spectrometers will always measure signal intensity ratios instead. The actual problem is that the measured intensity ratios differ more or less from the isotope ratios. The difference can be up to more than 10 % in case of lithium while it‘s below 1 % in case of the heavier elements like lead or uranium. Consequently, the signal intensity ratios are expressed for example in V/V depending on the type of mass spectrometer you are using, while the isotope ratios are expressed in mol/mol. This phenomenon is called Instrumental Isotopic Fractionation (or short IIF) but the more common name is still mass bias (even though this name is not entirely correct). To convert the measured into the isotope ratio usually a simple multiplication with a so-called correction (or short K) factor is done. Therefore, the problem is to determine the K factor. In absence of isotope reference materials the golden route is via gravimetric isotope mixtures, which will be explained within the presentation.
Isotope reference materials
(2022)
The variation of isotope ratios is increasingly used to unravel natural and technical questions. In the past, the investigation and interpretation of such variations was the field of a limited number of experts. With new upcoming techniques and research topics in the last decades, such as provenance or food authenticity studies, the number of published isotope data strongly increased. Instrumental developments such as the enhancement of inductively coupled plasma mass spectrometers (ICP-MS) from an instrument for simple quantitative analysis to highly sophisticated isotope ratio machines influenced this process significantly. While in former times only experts in mass spectrometry were able to produce reliable isotope data, nowadays many laboratories, never been in touch with mass spectrometry before, produce isotope data with an ICP-MS. Isotope reference materials (iCRM) are indispensable to enable a reliable method validation or in rare cases even SI-traceability. The fast development and the broad availability of ICP-MS also lead to an expansion of the classical research areas and new elements are under investigation. Irrespective of the investigated element or the knowledge of the user all isotope ratio applications require reference materials either for correction of instrumental isotope fractionation, for method validation or to provide a common accepted basis as needed for delta measurements. This presentation will outline the basic principles and illustrate the urgent need for new iCRMs. Consequently, the production and certification of iCRMs will be discussed and illustrated by examples of already completed certification projects. Finally, plans for future iCRMs to be produced at BAM will be presented.
Introduction: The influence of copper, iron and zinc concentrations on the formation of ß-amyloid plaques and neurofibrillary tangles in Alzheimer’s disease (AD) is widely discussed in the community. The results from human and animal studies so far are mixed with some studies showing a correlation and others not. From a number of studies, it is known that disease state and isotopic composition of essential elements can be coupled.
Aim: The aim of the study was to identify changes in element content and isotopic composition in two transgenic mouse models used in AD research compared to their genetic WT relatives and to establish whether element content and isotopic signature between different laboratories is comparable.
Methods: ß-amyloid (5xFAD) and tau overexpressing (L66) mice together with their matching wild-types were bred at dedicated facilities in accordance with the European Communities Council Directive (63/2010/EU). Serum and brain were sampled after sacrifice and the samples distributed among the participants of the study. The tissues were acid digested for total element determination and high-precision isotope ratio determination. Element content was determined by either sector-field or quadrupole-based inductively coupled plasma mass spectrometry (ICPMS). For the determination of isotope ratios multi-collector ICPMS was used.
Results: Total copper content was significantly higher for L66 and their matched WT compared to 5xFAD and WT. Brains of L66 mice contained more Fe in brain than their WT, Zn and Cu were not significantly different between L66 and WT. Whereas 5xFAD mice had a slightly lower Cu and slightly higher Zn concentration in brain compared to WT. The isotopic signature in brain of L66 mice for Fe was different from their controls, whereas Zn isotope ratios were influenced in 5xFAD mice compared to their WT. The Cu isotopic ratio did not seem to be influenced in either strain. In serum, the shifts were less pronounced.
Conclusion: Even though neither Tau-protein nor amyloid precursor protein are known to be metal-dependent / -containing proteins, the overexpression of both influences the Fe, Cu and Zn metabolism in brain and to some extent also in serum as can be seen not only using total element determination but probably more clearly studying the isotopic signature of Fe, Cu and Zn.
IRWG strategy update
(2022)
A new method combining isotope dilution mass spectrometry (IDMS) and standard addition has been developed to determine the mass fractions w of different elements in complex matrices: (a) silicon in aqueous tetramethylammonium hydroxide (TMAH), (b) sulfur in biodiesel fuel, and (c) iron bound to transferrin in human serum. All measurements were carried out using inductively coupled plasma mass spectrometry (ICP–MS). The method requires the gravimetric preparation of several blends (bi)—each consisting of roughly the same masses (mx,i) of the sample solution (x) and my,i of a spike solution (y) plus different masses (mz,i) of a reference solution (z).
Only these masses and the isotope ratios (Rb,i) in the blends and reference and spike solutions have to be measured. The derivation of the underlying equations based on linear regression is presented and compared to a related concept reported by Pagliano and Meija. The uncertainties achievable, e.g., in the case of the Si blank in extremely pure TMAH of urel (w(Si)) = 90% (linear regression method, this work) and urel (w(Si)) = 150% (the method reported by Pagliano and Meija) seem to suggest better applicability of the new method in practical use due to the higher robustness of regression analysis.