Chemie und Prozesstechnik
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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.
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.
In many scientific fields, isotopic analysis can offer valuable information. Up to date, typically bulk analysis is aimed at measuring the isotopic composition of the entire elemental content of the sample. However, the analyte element is usually present under the form of different species. Thus, separating species of interest from one another and from matrix components prior to isotope ratio measurements can provide species-specific isotopic information, which could be used for tracing the origin of environmental pollutants and elucidation of (environmental) speciation. Using on-line hyphenations of separation techniques with multicollector-ICP-MS (MC-ICP-MS) can save time and effort and enables the analysis of different species during a single measurement. Whereas some works hyphenating GC and IC with MC-ICP-MS have already been reported, LC and CE hyphenations are still inadequately represented based on the capabilities of these separation techniques.
In this work, we developed an on-line hyphenation of CE with multicollector-ICP-MS (CE/MC-ICP-MS) for isotopic analysis of sulfur species using a multiple-injection approach for instrumental mass bias correction by standard-sample bracketing. With this method, the isotopic composition of sulfur in sulfate originating from river water could be analyzed without sample preparation. The results were compared to data from off-line analysis of the same samples to ensure accuracy. The precision of the results of the on-line measurements was promising regarding the differentiation of the river systems by the isotopic signature of river water sulfate. The great potential of this method is based on the versatility of the applied separation technique, not only in the environmental field but also for, e.g., biomolecules, as sulfur is the only covalently bound constituent of proteins that can be analyzed by MC-ICP-MS.
In many scientific fields, isotopic analysis can offer valuable information. Up to date, typically bulk analysis is aimed at measuring the isotopic composition of the entire elemental content of the sample. However, the analyte element is usually present under the form of different species. Thus, separating species of interest from one another and from matrix components prior to isotope ratio measurements can provide species-specific isotopic information, which could be used for tracing the origin of environmental pollutants and elucidation of (environmental) speciation. Using on-line hyphenations of separation techniques with multicollector-ICP-MS (MC-ICP-MS) can save time and effort and enables the analysis of different species during a single measurement. Whereas some works hyphenating GC and IC with MC-ICP-MS have already been reported, LC and CE hyphenations are still inadequately represented based on the capabilities of these separation techniques.
In this work, we developed an on-line hyphenation of CE with multicollector-ICP-MS (CE/MC-ICP-MS) for isotopic analysis of sulfur species using a multiple-injection approach for instrumental mass bias correction by standard-sample bracketing. With this method, the isotopic composition of sulfur in sulfate originating from river water could be analyzed without sample preparation. The results were compared to data from off-line analysis of the same samples for validation. The repeatability of the results of the on-line measurements was promising regarding the differentiation of the river systems by the isotopic signature of river water sulfate. The great potential of this method is based on the versatility of the applied separation technique, not only in the environmental field but also for, e.g., biomolecules because sulfur is the only covalently bound constituent of proteins that can be analyzed by MC-ICP-MS.
In many scientific fields, isotopic analysis can offer valuable information, e.g., for tracing the origin of food products, environmental contaminants, forensic and archaeological samples (provenance determination), for age determination of minerals (geochronological dating) or for elucidating chemical processes. Up to date, typically bulk analysis is aimed at measuring the isotopic composition of the entire elemental content of the sample. However, the analyte element is usually present under the form of different species. Thus, separating species of interest from one another and from matrix components prior to isotope ratio measurements can provide species-specific isotopic information, which could be used for tracing the origin of environmental pollutants and elucidation of (environmental) speciation. Using on-line hyphenations of separation techniques with multicollector-ICP-MS (MC-ICP-MS) can save time and effort and enables the analysis of different species during a single measurement.
In this work, we developed an on-line hyphenation of CE with multicollector-ICP-MS (CE/MC-ICP-MS) for isotopic analysis of sulfur species. With this method, the isotopic composition of sulfur in sulfate originating from river water could be analyzed without sample preparation. The results were compared with data from off-line analysis of the same samples to ensure accuracy. The precision of the results of the on-line measurements was high enough to distinguish the rivers from one another by the isotopic signature of the river water sulfate. Next to environmental applications, a future field could be species-specific isotopic analysis of biomolecules, as sulfur is the only covalently bound constituent of proteins which can be analyzed by MC-ICP-MS.
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.
Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful method for the matrix-independent quantitative analysis of target elements. Developed for the use in inorganic trace analysis, ICP-MS is nowadays a valuable tool for bioanalytical questions. Especially the use of ICP-MS for quantitative proteomics by measuring heteroatoms has gained recognition in the last decade, considering that established quantification methods like organic mass spectrometry depend on labelling of the target protein or the existence of matched protein and peptide standards. The need for reliable quantification of proteins is continuously growing, but only a limited number of well-characterized and quantified protein standards are available so far. Accurately quantified, traceable protein standards are necessary to ensure comparability of measurements between laboratories, not only in basic research but also in a clinical context. One example of this is the Alzheimer’s disease biomarker tau protein. However, existing tau standards lack comparability, emphasizing the need for a well-quantified protein standard.
Therefore, we developed a method for the quantification of pure proteins via sulfur isotope dilution ICP-MS (IDMS). As sulfur is present in two amino acids, cysteine and methionine, it exists in nearly all proteins and can be used for the quantification of proteins of known stoichiometry. We employed simple offline strategies for the separation of non-protein bound sulfur species. Quantification of these contaminations by IDMS allows for correction of the protein content and enables reliable protein quantification. We report the protein mass fractions of a standard reference material and commercially available proteins determined by sulfur IDMS, including the expanded uncertainties. The developed method can be applied for the reliable and traceable quantification of pure proteins for use as in-house standards. Here, we successfully used this method for the quantification of the tau protein.
Diatoms are located at the bottom of the food chain. Toxicological relevant metals can possibly accumulate within the food web and cause harmful effects. Diatoms are a test system in ecotoxicology. Toxicological effects weaken the growth of algae which is by default investigated by means of fluorescence detection. On basis of the expose concentration as well as obtained fluorescence data potential threshold exceedance in e.g. surface waters is assessed.
However, this approach does not allow for the determination of “real” accumulated metal concentration in diatoms. Common approaches are based on bulk analysis via e.g. ICP-MS, ICP-OES or AAS. But, biological variability is completely disregarded.
To tackle this problem, alternative approaches are highly needed. Within the last years, sp-ICP-MS for nanoparticle as well as single cell analysis turned out as a powerful technique to analyze metal contents as well as size distributions on broad size range. But, common ICP-MS systems do not allow for multi-element detection within single particle/cell events. Thus, simultaneous MS detection devices are needed - just recently, ICP-ToF-MS experienced a revival.
Within our previous work, we developed an automated sample introduction system based on a HPLC system on-line with single particle-ICP-MS, which allowed for ionic background separation and single algae analysis. However, for unambiguous tracing several fingerprint elements and multielement analysis in single algae (diatoms) is needed. Thus, we coupled our previous setup on-line to ICP-ToF-MS. Test diatom species were exposed to test substances (Zn) as well as nanoparticles (FeNPs).
The developed setup allowed for a fast, automated and multielement analysis in single diatoms. Furthermore, we combined our approach with multivariate data assessment - multielement detection of characteristic fingerprint elements allowed for an unambiguous diatom tracing. Clustering of diatoms according to metal exposure concentration levels was enabled. Our approach is a new potential tool in ecotoxicological testing.
An introduction into absolute isotope ratios is given, with application fields ranging from fundamental science to geochronology and forensics. This is followed by a proposal for developing new calibration approaches for obtaining absolute isotope ratios at unrivaled uncertainty levels. This new developments will set the basis for improvements in all scientific fields.