Chemische Charakterisierung und Spurenanalytik
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Eingeladener Vortrag
- nein (4)
Iron isotopes are used in a variety of fields from e.g., geologic question to medical applications. Measurements of iron isotopes are usually performed as delta measurements to an artificial based delta zero standard. In the case of Fe isotopes is that delta zero standard IRMM-014, a pure Fe metal. Unfortunately, that conventional delta zero reference material defining the 56/54Fe scale is out of stock and therefore unavailable. To overcome that situation and fulfill the need for laboratories that measure Fe isotope on a regular basis we will provide a set of solutions with IRMM-014 and a second anchor point for Fe isotope ratio measurements that is based on a pure Fe metal. This new second anchor point, a high purity Fe from BAM, will be calibrated against IRMM-014 and can be used as bracketing standard or as reference value for stable Fe isotope measurements.
We are in the good situation that BAM ordered a large stock of IRMM-014 several years ago. That stock of IRMM-014 Fe cubes and IRMM-014 Fe wires will be dissolved in 6M HCl in a large quantity. The new anchor point, the high purity Fe metal, that is commercially available at BAM, is a pure Fe metal with only trace amounts of impurities. The high purity BAM material will also be dissolved in 6M HCl in large quantity. Several aliquots of both solutions will be measured on the Neptune Plus MC-ICP-MS to define this second anchor point with a low uncertainty. Further will we send several aliquots of both solutions to different laboratories to also measure this second anchor point of high purity Fe on the 56/54Fe scale.
We will report the values of that study on BAM high purity Fe and will provide a guide for scale conversion to the IRMM-014 scale and for uncertainty calculation to use that new anchor point instead of the exhausted IRMM-014.
The variation of isotope ratios is increasingly used to unravel natural and technical questions. With new upcoming techniques and research topics in the last two decades, such as material provenance or food authenticity to animal and human migration studies, the number of published isotope data has strongly increased. Here, isotope reference materials are indispensable to enable a reliable method validation or even SI-traceability. The fast development and broad availability of inductively coupled plasma mass spectrometry instrumentation (ICP-MS) also lead to an expansion of the classical research areas and new elements are under investigation. Owing to this large expansion of the field, the production and certification of isotope reference materials for calibration and validation is lagging behind, even for classical applications such as conventional 87Sr/86Sr isotope ratio analysis. To improve this situation, BAM organized an interlaboratory comparison (ILC) comprising of thirteen international laboratories for the characterisation of 87Sr/86Sr isotope ratios in geochemical and industrial reference materials. Six reference materials (four cements and two rocks) were provided as powder requiring extensive sample preparation prior to isotopic measurement. Additional requirements included the use of the conventional method for obtaining 87Sr/86Sr isotope ratios, also known as radiogenic 87Sr/86Sr isotope ratios, and the assessment of the measurement uncertainty. The primary goal was to evaluate potential differences in the application of multicollector thermal ionization mass spectrometry (MC-TIMS) and multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) for conventional 87Sr/86Sr isotope ratio determination, with a secondary goal to provide reference values for the 87Sr/86Sr isotope ratios in these potential new reference materials. All reported results are accompanied by an uncertainty statement and are traceable to the conventional method, which will be described in detail within this presentation. Current state-of-the-art statistical models were used to ensure the proper evaluation of the reported results and their associated measurement uncertainties within the frame of this ILC. Combined with results from appropriate homogeneity assessment, reference values for 87Sr/86Sr isotope ratios will be assigned.
This paper discusses the feasibility of a novel strategy based on the combination of bioprinting nano-doping technology and laser ablation-inductively coupled plasma time-of-flight mass spectrometry analysis for the preparation and characterization of gelatin- based multi-element calibration standards suitable for quantitative imaging. To achieve this, lanthanide up-conversion nanoparticles were added to a gelatin matrix to produce the bioprinted calibration standards. The features of this bioprinting approach were com- pared with manual cryosectioning standard preparation, in terms of throughput, between batch repeatability and elemental signal homogeneity at 5 μm spatial resolution. By using bioprinting, the between batch variability for three independent standards of the same concentration of 89 Y (range 0–600 mg/kg) was reduced to 5% compared to up to 27% for cryosectioning. On this basis, the relative standard deviation ( RSD ) obtained between three independent calibration slopes measured within 1 day also reduced from 16% (using cryosectioning ) to 5% (using bioprinting), supporting the use of a single standard preparation replicate for each of the concentrations to achieve good calibration performance using bioprinting. This helped reduce the analysis time by approximately 3-fold. With cryosectioning each standard was prepared and sectioned individually, whereas using bio-printing it was possible to have up to six different standards printed simultaneously, reducing the preparation time from approximately 2 h to under 20 min (by approxi- mately 6-fold). The bio-printed calibration standards were found stable for a period of 2 months when stored at ambient temperature and in the dark.
For more than 110 years, BAM has been producing reference materials for a wide range of application fields. With the development of new analytical methods and new applications as well as continuously emerging more stringent requirements of laboratory accreditation with regard to quality control and metrological traceability, the demand and requirements for reference materials are increasing. This trend article gives an overview of general developments in the field of reference materials as well as developments in selected fields of application in which BAM is active. This includes inorganic and metal analysis, gas analysis, food and consumer products, and geological samples. In addition to these more traditional fields of application, developments in the areas of optical spectroscopy, particulary fluorescence methods, and nanomaterials are considered.
MALDI-TOF-MS-Based Identification of Monoclonal Murine Anti-SARS-CoV-2 Antibodies within One Hour
(2022)
During the SARS-CoV-2 pandemic, many virus-binding monoclonal antibodies have been developed for clinical and diagnostic purposes. This underlines the importance of antibodies as universal bioanalytical reagents. However, little attention is given to the reproducibility crisis that scientific studies are still facing to date. In a recent study, not even half of all research antibodies mentioned in publications could be identified at all. This should spark more efforts in the search for practical solutions for the traceability of antibodies. For this purpose, we used 35 monoclonal antibodies against SARS-CoV-2 to demonstrate how sequence-independent antibody identification can be achieved by simple means applied to the protein. First, we examined the intact and light chain masses of the antibodies relative to the reference material NIST-mAb 8671. Already half of the antibodies could be identified based solely on these two parameters. In addition, we developed two complementary peptide mass fingerprinting methods with MALDI-TOF-MS that can be performed in 60 min and had a combined sequence coverage of over 80%. One method is based on the partial acidic hydrolysis of the protein by 5 mM of sulfuric acid at 99 degrees C. Furthermore, we established a fast way for a tryptic digest without an alkylation step. We were able to show that the distinction of clones is possible simply by a brief visual comparison of the mass spectra. In this work, two clones originating from the same immunization gave the same fingerprints. Later, a hybridoma sequencing confirmed the sequence identity of these sister clones. In order to automate the spectral comparison for larger libraries of antibodies, we developed the online software ABID 2.0. This open-source software determines the number of matching peptides in the fingerprint spectra. We propose that publications and other documents critically relying on monoclonal antibodies with unknown amino acid sequences should include at least one antibody fingerprint. By fingerprinting an antibody in question, its identity can be confirmed by comparison with a library spectrum at any time and context.
A method, based on electrothermal vaporization (ETV) coupled to inductively coupled plasma optical emission spectrometry (ICP OES), has been optimized for direct solid sampling analysis of soda-lime glass - the most common type of industrially manufactured glass. This method allows fast and reliable quantification of the main elements - Al, Ca, K, Mg, Na, and Si - and trace elements - As, Ba, Cd, Ce, Co, Cr, Cu, Fe, Mn, Mo, Ni, (P), Pb, Sb, (Se), Sn, Sr, Ti, V, Zn, and Zr. In the presented ETV-ICP OES method, calibration is performed predominantly with matrix-free synthetic samples. This metrological advantage is normally not achieved with direct solid sampling methods and is one of the goals of the present study. In a certification interlaboratory comparison for the soda-lime glass CRM BAM-S005c, 2 out of 16 laboratories employed the ETV-ICP OES method. An improved analytical performance was obtained compared with the results of laboratories that used conventional liquid ICP OES. For both methods, the average relative deviations between the laboratory results and certified values as well as the average values of relative standard deviation were with a few exceptions <10%, in most cases even <5%, which indicated high trueness and precision.
An alternative method for lithium isotope amount ratio analysis based on a combination of high-resolution atomic absorption spectrometry and spectral data analysis by machine learning (ML) is proposed herein. It is based on the well-known 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 the state-of-the-art high-resolution continuum source graphite furnace atomic absorption spectrometry. 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, previously determined by a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS). The calibration ML model was validated with two certified reference materials (LSVEC and IRMM-016). The procedure was applied toward the isotope amount ratio determination of a set of stock chemicals (Li2CO3, LiNO3, LiCl, and LiOH) and a BAM candidate reference material NMC111 (LiNi1/3Mn1/3Co1/3O2), a Li-battery cathode material. The results of 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, as demonstrated for samples ranging from approximately −3 to +15‰. To assess its suitability to technical applications, the NMC111 cathode candidate reference material was analyzed using high-resolution continuum source atomic absorption spectrometry with and without matrix purification. The results obtained were metrologically compatible with 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.
Reference Materials at BAM
(2021)