Chemische Charakterisierung und Spurenanalytik
Filtern
Erscheinungsjahr
- 2019 (208) (entfernen)
Dokumenttyp
- Vortrag (98)
- Zeitschriftenartikel (67)
- Posterpräsentation (36)
- Beitrag zu einem Tagungsband (2)
- Dissertation (2)
- Buchkapitel (1)
- Preprint (1)
- Forschungsbericht (1)
Sprache
- Englisch (161)
- Deutsch (45)
- Mehrsprachig (2)
Schlagworte
- ICP-MS (13)
- Mikroplastik (13)
- Process Analytical Technology (12)
- Isotope analysis (9)
- LIBS (9)
- Laser ablation (9)
- Online NMR Spectroscopy (9)
- CONSENS (8)
- Digitalisierung (8)
- HR-CS-MAS (8)
Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (158)
- 1.1 Anorganische Spurenanalytik (46)
- 6 Materialchemie (40)
- 1.4 Prozessanalytik (38)
- 1.6 Anorganische Referenzmaterialien (28)
- 1.7 Organische Spuren- und Lebensmittelanalytik (28)
- 1.8 Umweltanalytik (28)
- 6.6 Physik und chemische Analytik der Polymere (21)
- 6.3 Strukturanalytik (18)
- 1.9 Chemische und optische Sensorik (13)
Eingeladener Vortrag
- nein (98)
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is nowadays an established multi-elemental analysis and mapping technique. It was shown that LA-ICP-MS can visualize the elemental distribution within tissue thin sections or cell samples. Quantification is possible by using appropriate matrix-matched calibration samples. Besides naturally occurring elements and metals from contrast agents, biomolecules using metal-tagged antibodies were detected in different bio-medical samples. By combining the results with findings from histology, magnetic resonance imaging (MRI) and other techniques disease related changes like alterations of the extracellular matrix can be investigated.
Single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) has become an effective tool for the detection and quantification of inorganic nanoparticles (NPs). While sizing of NPs suspended in water is relatively straightforward by sp-ICP-MS, accurate mass quantification of NPs in complex media, such as consumer products and natural systems still remains a challenge. When NPs are suspended in a complex medium, the matrix may affect the analyte sensitivity and lead to inaccurate NP sizing. Here, we investigate the use of an online microdroplet calibration system to size NPs in a single step. In this setup, microdroplets—which are used as the calibrant to determine elemental sensitivities—and nebulized NP-containing solutions are introduced concurrently into the ICP via a dual-inlet sample introduction system. Because calibrant microdroplets and analyte NPs experience the same plasma conditions, both the microdroplets and the NPs are subjected to the same matrix-related signal enhancement or suppression. In this way, the microdroplet calibration standards are automatically matrix matched with the NP-containing solution. The online microdroplet calibration system is combined with an ICP-TOFMS instrument for simultaneous measurement of multiple elements in microdroplets and NPs. We investigate the ability of online microdroplet calibration to compensate for matrix effects through a series of experiments, in which Ag and Au NPs are measured with variable plasma-sampling positions, varying concentrations of HCl and HNO3, varying concentrations of single element solutions, and high concentrations of a salt matrix, i.e. phosphate buffered saline (PBS). Through these experiments, we demonstrate that the online microdroplet calibration strategy provides a matrix-independent mass quantification of analyte NPs in the presence of several established types of matrix effects, including acid effects, space-charge effects, and ionisation suppression. In results presented here, we focus on the size determination of the NPs.
1,3,5-Tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione (TDBP-TAZTO) is an emerging brominated flame retardant which is widely used in several plastic materials (electric and electronic equipment, musical instruments, automotive components).
However, until today, no photochemical studies as well as the identification of possible phototransformation products (PTPs) were described in literature. Therefore, in this study, UV-(C) and simulated sunlight irradiation experiments were performed to investigate the photolytic degradation of TDBP-TAZTO and to identify relevant PTPs for the first time. The UV-(C) Irradiation experiments show that the photolysis reaction follows a first-order kinetic model. Based on this, the photolysis rate constant k as well as the half-life time t1/2 were calculated to be k = (41 ± 5 ×10−3) min−1 and t1/2=(17±2) min. In comparison, a minor degradation of TDBP-TAZTO and no formed phototransformation products were obtained under simulated sunlight. In order to clarify the photochemical behavior, different chemicals were added to investigate the influence on indirect photolysis: (i) H2O2 for generation of hydroxyl radicals and (ii) two quenchers (2-propanol, sodium azide) for scavenging oxygen species which were formed during the irradiation experiments. Herein, nine previously unknown PTPs of TDBP-TAZTO were detected under UV-(C) irradiation and identified by HPLC-(HR)MS. As a result, debromination, hydroxylation, and dehydrobromination reactions could be presumed as the main degradation pathways by high-resolution mass spectrometry. The direct as well as the OH radical-induced indirect photolysis were observed.
Mykotoxine in Lebensmitteln stellen weltweit Probleme dar, Zearalenon in Speiseöl ist ein solches. Neue Hydrazinbasierte Analyseverfahren können jetzt helfen, den EU-Grenzwert besser zu kontrollieren. Aber auch die Strukturaufklärung von Transformationsprodukten und verlässliche Kalibrierstandards sind aktuelle Herausforderungen.
We have efficiently produced collagen-rich microstructures in fibroblast multicellular spheroids (MCSs) as a three-dimensional in vitro tissue analog to investigate silver (Ag) nanoparticle (NP) penetration. The MCS production was examined by changing the seeding cell number (500 to 40,000 cells) and the growth period (1 to 10 days). MCSs were incubated with Ag NP suspensions with a concentration of 5 μg/mL for 24 h. For this study, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to visualize Ag NP localization quantitatively. Thin sections of MCSs were analyzed by LA-ICP-MS with a laser spot size of 8 μm to image distributions of 109Ag, 31P, 63Cu, 66Zn, and 79Br. A calibration using a NP suspension was applied to convert the measured Ag intensity into the number of NPs present. The determined numbers of NPs ranged from 30 to 7200 particles in an outer rim of MCS. The particle distribution was clearly correlated with the presence of 31P and 66Zn and was localized in the outer rim of proliferating cells with a width that was equal to about twice the diameter of single cells. Moreover, abundant collagens were found in the outer rim of MCSs. For only the highest seeding cell number, NPs were completely captured at the outer rim, in a natural barrier reducing particle transport, whereas Eosin (79Br) used as a probe of small molecules penetrated into the core of MCSs already after 1 min of exposure.
Plasmas as atomization and ionization/excitation sources have been used for more than 50 years. The term plasma spectrochemistry was introduced in the 1980s and is nowadays a topic of annual reviews and different conferences such as the Winter Conference on Plasma Spectrochemistry (held in USA), the European Winter Conference on Plasma Spectrochemistry, and The Nordic conference on Plasma Spectrochemistry.
The development of advanced materials is inherently connected with improvements in analytical chemistry, and often is the driving force for method development in plasma-based spectrometry. Besides the determination of physical characteristics such as tensile strength, density, and conductivity, the investigation of their chemical constituents down to the trace and ultra-trace levels becomes more and more important and, therefore, the demand of sensitive and precise analytical methods is growing. In some cases, the determination of the average content is a sufficient result, for instance for the characterisation of raw material or waste management. However, lately laterally resolved analysis, depth profiling of layered materials and characterization of high purity materials are of growing importance. The aim of this article is to give an introduction into plasma spectrometry and its application in materials science. A theoretical overview of the used plasma techniques and a review on applications with a special focus on direct solid sampling will be presented.
The performance of glow discharge mass spectrometry (GD-MS) is investigated for the accurate quantification of metallic impurities and oxygen in solid samples using the fast flow source GD-MS instrument ELEMENT GD.
Different quantification approaches based on relative and absolute sensitivity factors are evaluated for the determination of metallic impurities using three sample matrixes (Al, Cu and Zn). The effect of the discharge conditions (voltage, current, discharge gas pressure/flow) on the sensitivity is investigated and the parameters are optimized to favour matrix independent calibrations. Improved standard relative sensitivity factors (StdRSFs) are calculated under optimal conditions based on multi-matrix calibrations. The sputtering rate corrected calibration is also presented as a multi-matrix calibration approach.
The capabilities of GD-MS for oxygen determination are also investigated using a set of new conductive samples containing oxygen with mass fractions in the percent range in three different matrices (Al, Mg and Cu) produced by a sintering process. Poor limits of detection (in the order of g/kg) were obtained as consequence of the reduced sensitivity of oxygen in GD-MS and high oxygen background signal intensity as well as its variations. The absolute sensitivity procedure is shown as a matrix-independent approach, which provides quantitative values consistent with those obtained by carrier gas hot extraction (CGHE).
Elemental impurities (EI) in medicinal products for human use are limited according to ICH guideline Q3D, which is in force since December 2017 in Europe and US.
As a consequenceconsequence, the relevant texts of the European Pharmacopoeia (Ph. Eur.) and the United States Pharmacopeia (USP) have been modified to reflect and complement ICH Q3D, providing details on the analytical methods to be used. In those chapters (Ph. Eur. 2.4.20., USP <233>), it is stated that for the quantification of elemental impurities, certified reference materials (CRM) from a national metrology institute (NMI) or reference materials that are traceable to the CRM of an NMI should be used.
The Ph. Eur. has so far implemented elemental impurity standards of this type for the four most important elemental impurities i.e. those corresponding to ICH Q3D Class 1: lead, cadmium, mercury and arsenic.
The poster provides details on the development of those four reference standards, which was undertaken in partnership with a major institute accredited CRM producer (JRC, European Commission), and a national metrology institute (BAM and PTB, Germany), and a Designated Institute and accredited CRM producer (BAM, Germany). The reference standards were established and characterised according to rigorous metrological principles and are supplied with extended supporting information as required for the intended use.
After successful completion of the project, the four reference standards have been added to the Ph.Eur. catalogue and are in distribution. It is expected that another three elemental impurity standards will be implemented and made available to users within the next three years.
Shortly after founding the CCQM in 1993, the first key comparison (CCQM-K2) about the determination of Cd and Pb content in river water was hosted by IRMM. It has been clear from the beginning that for the determination of an element mass fraction in a matrix, accurate reference solutions would be the key point for a metrologically sound analysis. Triggered by the not entirely satisfactory results it was decided to investigate the basis of all measurements: the reference solutions. Thus in 1999, CCQM-K8, hosted by EMPA/LNE, started the tedious but indispensable work on elemental solutions standards.
Additionally, PTB, BAM and Merck KGaA initiated a project to establish a traceability system for inorganic analysis based on accurate monoelemental solutions. Within this unique approach ten high purity reference materials were fully characterized, and solutions were prepared gravimetrically thereof. These materials (forming the primary standards of elemental analysis) are available for NMIs/DIs from BAM.
CCQM-P46 (Cu, Mg, Rh) demonstrated the actuality of the topic and the challenges to prepare elemental solutions for every element. The accurate preparation and use of monoelemental solutions is consequently reflected in the recurrent conduct of (key) comparisons: CCQM-P149 (purity of zinc), CCQM-K87 (Co, Cr, Pb), and the current CCQM-K143/P181 (Cu solutions), to name only a few in a long series.
Is it necessary to put so much effort into the preparation of reference solutions? It clearly is! An example outside the world of academia: Recently, EDQM*, PTB, BAM and JRC have developed monoelemental reference standards traceable to the SI for toxic elements in support of the chapters of the European Pharmacopoeia, related to the analysis of elemental impurities in medicinal products. A new ICP OES method has been established allowing the comparison of two 1 g/kg mercury solutions with an outstandingly small uncertainty of Urel(w(Hg)) = 0.16 %. However, this technical progress would not have been possible without the ongoing effort of the metrological community within 25 years of research in the field of high accuracy monoelemental solutions.
* EDQM: European Directorate for the Quality of Medicines and HealthCare