Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (179)
- Vortrag (46)
- Beitrag zu einem Tagungsband (10)
- Beitrag zu einem Sammelband (3)
- Sonstiges (1)
- Posterpräsentation (1)
Schlagworte
- LIBS (13)
- ICP-MS (12)
- ELISA (8)
- LC-MS/MS (8)
- Laser ablation (8)
- Acoustic levitation (7)
- Speciation (7)
- Traceability (6)
- Calibration (5)
- Characterization (5)
- Laser induced plasma (5)
- Laser-induced breakdown spectroscopy (5)
- Nanoparticles (5)
- Caffeine (4)
- Copper (4)
- Fluorescence (4)
- Immunoassay (4)
- Ionization (4)
- LA-ICP-MS (4)
- SEM (4)
- Wastewater (4)
- Water (4)
- XRF (4)
- Ambient mass spectrometry (3)
- Analytical Sciences (3)
- Antibody (3)
- Bisphenol A (3)
- Bisphenol A degradation (3)
- Carbamazepine (3)
- Chemometrics (3)
- Click Chemistry (3)
- EDS (3)
- Fenton oxidation (3)
- Graphite furnace (3)
- HR-CS-MAS (3)
- High resolution (3)
- In-situ (3)
- Inductively coupled plasma mass spectrometry (ICP-MS) (3)
- Isotope dilution analysis (3)
- Laser-induced plasma (3)
- Levitated droplets (3)
- MALDI (3)
- Nanocatalysts (3)
- Online NMR Spectroscopy (3)
- Photodegradation (3)
- Pollen (3)
- Polymer (3)
- Process Analytical Technology (3)
- Quantification (3)
- Raman spectroscopy (3)
- Single particle ICP-MS (3)
- Surface water (3)
- SyXRD (3)
- Synchrotron radiation (3)
- Uncertainty (3)
- X-Ray diffraction (3)
- Abwasser (2)
- Bioconjugation (2)
- Cell (2)
- Cells (2)
- Cement hydration (2)
- Chemical analysis (2)
- Crystallization (2)
- DPSS laser (2)
- ERM (2)
- ESI-TOF-MS (2)
- Electrochemical oxidation (2)
- Emission spectroscopy (2)
- Fenton (2)
- Firework display (2)
- Gadolinium (2)
- Gadolinium-based contrast agents (2)
- HPLC (2)
- HPLC-ICP-MS (2)
- High repetition rate (2)
- Hydrophilic interaction chromatography (HILIC) (2)
- Imaging (2)
- In vitro (2)
- Indirect Hard Modeling (2)
- Isotope dilution (2)
- Katalysator (2)
- Lithium (2)
- Magnesium (2)
- Mass spectrometry (2)
- Metabolism (2)
- Micropollutants (2)
- Milk (2)
- Multivariate statistics (2)
- NEXAFS (2)
- Nanoparticle (2)
- Optical emission spectroscopy (2)
- Photooxidation (2)
- Plasma tomography (2)
- Polymorphism (2)
- Polystyrene (2)
- Raman (2)
- Reaction Monitoring (2)
- Reference material (2)
- Reference materials (2)
- Silver nanoparticles (2)
- Single cell analysis (2)
- Spectrometry (2)
- Steel slag (2)
- Sulfamethoxazole (2)
- Sulfur (2)
- X-ray diffraction (2)
- XPS (2)
- Zinc (2)
- 2D chromatography (1)
- 3R concept (1)
- A4F (1)
- AAS (1)
- ABC (1)
- AFM (1)
- AP-MALDI (1)
- Abel inversion (1)
- Ablation (1)
- Absolute quantum yield (1)
- Absorption spectrometry (1)
- Acceptance area (1)
- Accuracy (1)
- Acoustic levition (1)
- Aerosols (1)
- Ag nanoparticles (1)
- Aggregation (1)
- Air (1)
- Airbrush (1)
- AlCl (1)
- Algorithms (1)
- Aluminium (1)
- Ambient desorption/ionization mass spectrometry (1)
- Ambient pressure laser ionization (1)
- Analytical method (1)
- Anemia (1)
- Animal welfare (1)
- Anthropogenic markers (1)
- Array (1)
- Arrhenius model (1)
- Asymmetric flow filed-flow fractionation (1)
- Asymmetrical flow field flow fractionation (AF4) (1)
- Asymmetrical flow field-flow fractionation (AF4) (1)
- Atomic Absorption Spectrometry (1)
- Atomic absorption spectrometry (1)
- Automated Data Evaluation (1)
- BERM (1)
- Barium ion emission (1)
- Berlin tap water (1)
- Bio-Imaging (1)
- Bioavailability (1)
- Bioimaging (1)
- Bioimaging by LA-ICP-MS (1)
- Biological sewage plants (1)
- Biosensor development (1)
- Biotransformation (1)
- Boron (1)
- Boron isotopes (1)
- Boron monohydride (1)
- Brunauer-Emmett-Teller (1)
- CONSENS (1)
- CRM (1)
- Caesium (1)
- Calcium monofluoride (1)
- Calibrated SEM/EDS (1)
- Calibration-free analysis (1)
- Calibration-free laser-induced breakdown spectroscopy (1)
- Capillary electrophoresis (1)
- Capillary electrophoresis (CE) (1)
- Carbamazepin (1)
- Carbon dioxide (1)
- Carboxyl group (1)
- Cast iron (1)
- Catalytic wet peroxide oxidation (1)
- Cattle (1)
- Cement paste (1)
- Certified reference materials (1)
- Cetirizin (1)
- Cetirizine (1)
- Characterization of catalysts (1)
- Charge coupled devices (1)
- Chelex-100 (1)
- Chloride attack (1)
- Chlorides (1)
- Chlorine (1)
- Cluster (1)
- Cocaine (1)
- Colloidal suspension (1)
- Colloidal suspensions (1)
- Combustion gases (1)
- Comparability (1)
- Comparison (1)
- Complexing agents (1)
- Coproantibodies (1)
- Correlation analysis (1)
- Coumaric acid (1)
- Crosslinking (1)
- Cytochrome P450 CYP1A2 (1)
- DCTB (1)
- DP laser induced plasma (1)
- Dairy cows (1)
- Damaging mechanism (1)
- Detection limits (1)
- Detector efficiency (1)
- Detektorvergleich (1)
- Diatomic molecule (1)
- Dielectric barrier discharge (1)
- Digital (1)
- Digital transformation (1)
- Dissolution (1)
- Double-pulse LIBS (1)
- Dried droplet (1)
- Droplet (1)
- Droplets (1)
- Drugs on bills (1)
- Dual mode (1)
- Durability (1)
- Dyes (1)
- EC-LC-MS (1)
- EC/LC/MS (1)
- EC/MS (1)
- ECRM (1)
- EDS-TM001 (1)
- EDX (1)
- EDX-SEM (1)
- EDXD (1)
- ESEM (1)
- ESR (1)
- Echelle (1)
- Electrochemistry (1)
- Element determination (1)
- Elemental analytical mehtods (1)
- Elemental tagging (1)
- Emission standard (1)
- Emission/fluorescence ratio (1)
- Encapsulation (1)
- Endocrine disruptor (1)
- Endokrine Disruptoren (1)
- Energy transfer (1)
- Environment (1)
- Environmental monitoring (1)
- Environmental quality standard (EQS) (1)
- Enzyme-Linked Immunosorbent Assay (1)
- Enzyme-linked immunosorbent assay (1)
- Equivalence (1)
- Euro banknotes (1)
- Evaporation of droplets (1)
- Explosive (1)
- FT-Raman spectroscopy (1)
- FWHM (1)
- Fe nanoparticles metabolism (1)
- Fe-based highly active ionic liquids (1)
- Feces (1)
- Feed (1)
- Feeding regime (1)
- Ferrocene (1)
- Field flow fractionation (1)
- Fields (1)
- Five iron oxalate core–shell magnetite nanoparticles catalysts are evaluated as magnetic heterogeneous (1)
- Fixed-points (1)
- Fluorescence spectroscopy (1)
- Fluorescent glass (1)
- Focal distance (1)
- Foodstuffs (1)
- Fourier transform spectroscopy (1)
- Fungicide (1)
- GD-MS (1)
- GD-OES (1)
- GDMS (1)
- Gadolinium-uptake (1)
- Gas-phase NMR spectroscopy (1)
- Gd based contrast agents (1)
- Geochemical analysis (1)
- Germanium sulfide (1)
- Glow discharge (1)
- Glycan microarray (1)
- Gold (1)
- Gold-Nanopartikel (1)
- Grafting (1)
- Grimm type glow discharge (1)
- Guest complexe (1)
- HDEHP (1)
- HILIC (1)
- HILIC chromatography (1)
- HRMS (1)
- Hapten immunoassay (1)
- Heavy crude oil (1)
- High performance liquid chromatography (1)
- High resolution glow discharge mass (1)
- High-resolution continuum source absorption spectrometry (1)
- High-resolution continuum source graphite furnace atomic absorption spectrometry (1)
- Hollow cathode (1)
- Homogenität (1)
- Hormone (1)
- Human serum (1)
- Humic acid (1)
- Humic colloids (1)
- Hydrodynamic chromatography (HDC) (1)
- Hyphenated technique (1)
- ICCD CCD (1)
- IDMS (1)
- IR-MALDI (1)
- ITS-90 (1)
- IgG (1)
- Imaging MS (1)
- Immunization monitoring (1)
- Immunoassays (1)
- Impurities (1)
- In situ (1)
- In situ analysis (1)
- In-situ-Analyse (1)
- Integrating sphere (1)
- Interferometry (1)
- Internal standard (1)
- Inverse Abel Transform (1)
- Ion exchanged soda lime silicate glass (1)
- Ion mobility spectrometry (1)
- Ionic liquid (1)
- Ionic liquids (1)
- Ionmobility spectrometry (1)
- Iposomes (1)
- Iron nanoparticles (1)
- Iron ore (1)
- Iron-sucrose nanoparticles (1)
- Isotope (1)
- Isotope dilution mass spectrometry (1)
- Isotope ratios (1)
- Key comparison (1)
- Kolloidale Suspensionen (1)
- Konduktometrische Titration (1)
- Kramers background (1)
- Kreuzreaktivität (1)
- Kupfer (1)
- LA-ICP-MS based immunoassays (1)
- LA-ICP-OES (1)
- LC-MS (1)
- LCMSMS (1)
- Langmuir isotherm (1)
- Laser Induced Breakdown Spectroscopy (1)
- Laser ablation ICP-MS (1)
- Laser desorption ionization (1)
- Laser induced breakdown spectroscopy (LIBS) (1)
- Laser induced fluorescence (1)
- Laser-induced breakdown spectroscopy (LIBS) (1)
- Laser-spark (1)
- Laserablation (1)
- Light diffraction (1)
- Linear correlation (1)
- Liquid chromatography at critical conditions (1)
- Liquid matrix (1)
- Liver function tests (1)
- Luminescence (1)
- MALDI Massenspektrometrie (1)
- MALDI TOF mass spectrometry (1)
- MALDI mass spectrometry (1)
- MRI contrast agent (1)
- Machine learning (1)
- Magnetic coreshell nanocatalysts (1)
- Magnetic nanocatalyst (1)
- Magnetic resonance imaging (1)
- Magnetische Nanopartikel (1)
- Magnetpartikel (1)
- Manipulation (1)
- Mass spectrometry imaging (1)
- Material identification (1)
- Matrix (1)
- Matrix calculation (1)
- Matrix evaporation (1)
- Matrix influence (1)
- Matrix method (1)
- Matrix segregation (1)
- Matrix separation (1)
- Matrix-method (1)
- Matrixeffekte (1)
- Measuremment uncertainty (1)
- Mechanochemistry (1)
- Mega-dalton (1)
- Memory effect (1)
- Metal (1)
- Metal organic compounds (1)
- Metals (1)
- Metrology (1)
- Metrology in chemistry (1)
- Micro spot (1)
- Micro-hardness (1)
- Microdroplet generator (1)
- Microemulsion (1)
- Microparticles (1)
- Microphony (1)
- Microstructure (1)
- Mikropartikel (1)
- Mitigation (1)
- Modeling (1)
- Modelling (1)
- Modern art (1)
- Molecular absorption (1)
- Molecular masses (1)
- Molten glass (1)
- Monte Carlo simulation (1)
- Multi-element screening (1)
- Multiphoton fabrication (1)
- Multiplexing (1)
- Multivariate classification (1)
- Nano (1)
- Nano-carrier (1)
- Nanocrystals (1)
- Nanomaterials (1)
- Nanon (1)
- Nanoparticle characterization (1)
- Nanoparticles with same nominal diameter (1)
- Nifedipine (1)
- Nile red (1)
- Noncontact measurement technique (1)
- Noncontact ultrasonic transportation (1)
- Oberflächenfunktionalisierung (1)
- Oberflächenwasser (1)
- Online NMR (1)
- Online monitoring (1)
- Optically saturated fluorescence (1)
- Organic peroxides (1)
- Organophosphate agrochemicals (1)
- Orthogonal double pulse plasma (1)
- Oxidative metabolism (1)
- Parallel computing (1)
- Parallelising mode (1)
- Particle size range (1)
- Particles (1)
- Particulate matter (1)
- Peptide library (1)
- Pesticide (1)
- Pharmaceuticals (1)
- Pharmazeutische Cokristalle (1)
- Photo-Fenton oxidation (1)
- Photoacoustic spectroscopy (1)
- Photoluminescence (1)
- Photon generation yield (1)
- Pigments (1)
- Pin sample (1)
- Plants (1)
- Plasma diagnostics (1)
- Plasma spectrum analysis (1)
- Plasma temperature (1)
- Plume (1)
- Pollen germination (1)
- Pollen tube (1)
- Polycapillary X-ray optics (1)
- Polymerisation (1)
- Polymers (1)
- Polymerwissenschaften (1)
- Polystyrol (1)
- Polyurethane (1)
- Portland cement (1)
- Post-breakdown laser induced plasma (1)
- Precision (1)
- Pressure field (1)
- Primary reference gas mixtures (1)
- Primary standards (1)
- Principal component analysis (1)
- Process Control (1)
- Process Monitoring (1)
- Process analytical technology (1)
- Process control (1)
- Public funding (1)
- Pulse duration (1)
- Pure copper (1)
- Purification (1)
- Purity (1)
- Pyrotechnic articles (1)
- QuEChERS (1)
- Quality assurance (1)
- Quantitative NMR spectroscopy (1)
- Quantitative Online-NMR-Spektroskopie (1)
- Quantitative analysis (1)
- Quantum dots (1)
- Quantum yield (1)
- Quaternary oxides (1)
- RESS (1)
- Radiometry (1)
- Radon transform (1)
- Radon transform technique (1)
- Radon transform tomography of SP (1)
- Raman microscopy (1)
- Raman microspectroscopy (1)
- Reabsorption (1)
- Reaction products (1)
- Reactive azo dye degradation (1)
- Reconstructed ion chromatograms (1)
- Recycling (1)
- Reference (1)
- Reference measurements (1)
- Reference value (1)
- Reference value uncertainty (1)
- Reference-free XRF (1)
- Removal (1)
- Renewable copolymers (1)
- Reorganization (1)
- Ressortforschung (1)
- Ressortforschungseinrichtung (1)
- Rhodamine 6G (1)
- RoHS (1)
- Röntgenbeugung (1)
- SDHI-fungicide (1)
- SEC (1)
- SEM/EDS (1)
- SERS (1)
- SF-ICP-MS (1)
- SI (1)
- Saliva (1)
- Sample dissolution (1)
- Sample enrichment (1)
- Sample loss (1)
- Sample preparation (1)
- Scattering (1)
- Sector field mass spectrometry (1)
- Semi-lens (1)
- Sensitivity (1)
- Sensitized magnetic nanocatalysts (1)
- Serum (1)
- Shelf life (1)
- Side-window X-ray tube (1)
- Silicon (1)
- Silver (1)
- Simulation (1)
- Single Cell Analysis (1)
- Singlet oxygen (1)
- Singulettsauerstoff (1)
- Small objects (1)
- Sol-gel processes (1)
- Solar grade silicon (1)
- Solid phase extraction (1)
- Solvatochromism (1)
- Sonic spray (1)
- Sonic spray ionization (1)
- Sonochemical synthesis (1)
- Sound pressure (1)
- SpICP-MS (1)
- Spark-OES (1)
- Spatial heterodyne spectroscopy (1)
- Spatial investigations (1)
- Species-unspecific on-line isotope dilution (1)
- Spectral Modeling (1)
- Spectral correction (1)
- Spectral fluorescence standard (1)
- Spectrochemical analysis (1)
- Spectrometer (1)
- Spectrometer efficiency (1)
- Sporopollenin (1)
- Stability (1)
- Stable isotope (1)
- Standard (1)
- Standard-less analysis (1)
- Steel (1)
- Structure (1)
- Sulfate attack (1)
- Supercritical fluids (1)
- Surface coating (1)
- Surface-enhanced Raman scattering (1)
- Suspended particulate matter (1)
- Swelling (1)
- Synchrotron-radiation (1)
- Synthetic organic pigments (1)
- TATP (1)
- TEM (1)
- Terrorism (1)
- Thermal degradation (1)
- Thiol-ene click chemistry (1)
- Threshold values (1)
- ToF-SIMS (1)
- Toxicology (1)
- Trace elements (1)
- Transformation product (1)
- Transformation products (1)
- Transmission (1)
- Triacetone triperoxide (1)
- Tributyltin (TBT) (1)
- Two-dimensional off-line coupling (1)
- UPLC (1)
- UV degradation (1)
- Ultra high purity (1)
- Ultraschallfalle (1)
- Ultrasonic acoustic resonator (1)
- Ultrasonic trap (1)
- Urine (1)
- Vacuum distillation (1)
- Validation (1)
- Validierung (1)
- Wastewater marker (1)
- Water treatment (1)
- Wissenschaftliche Politikberatung (1)
- X-ray tube spectra (1)
- X-ray tube spectrum (1)
- X-ray-scattering (1)
- XRD (1)
- Xerogel (1)
- ZRM (1)
- Zementhydratation (1)
- Zeta-Potential (1)
- Zirconium (1)
- glass fibre paper (1)
- ion optics (1)
- muXRF (1)
- pH-Abhängigkeit (1)
- sensing (1)
- spray (1)
- surface enhanced Raman scattering (1)
- µSpot (1)
- ß-amino-cyclodextrin (1)
- “Click” chemistry (1)
Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (32)
- P Präsident (29)
- P.0 Präsident und andere (29)
- 1.1 Anorganische Spurenanalytik (15)
- 6 Materialchemie (12)
- 6.3 Strukturanalytik (8)
- 1.6 Anorganische Referenzmaterialien (6)
- 1.7 Organische Spuren- und Lebensmittelanalytik (6)
- 1.8 Umweltanalytik (5)
- 6.1 Oberflächen- und Dünnschichtanalyse (5)
Eingeladener Vortrag
- nein (46)
Bei der Entwicklung pharmazeutischer Wirkstoffe werfen Substanzen mit einer geringen Löslichkeit, Auflösungsrate und damit einhergehend schlechten Bioverfügbarkeit immer größere Probleme auf. Diese Eigenschaften und nicht etwa toxikologische Eigenschaften oder schlechte Wirksamkeit sorgen dafür, dass es weniger als 1 % aller Wirkstoffe bis in die Markteinführung schaffen. Eine Reihe von Ansätzen zur Verbesserung der schlechten Wasserlöslichkeit konnten bereits etabliert werden. Hierunter zählen die gezielte Salzbildung bzw. Salzscreening, Solubilisierung mit Cosolventien oder die Nutzung von Polymeren als mögliche Transportwege. Eine weitere Möglichkeit bietet die Bildung verschiedener polymorpher Formen, sowohl der Einzelkomponente als auch von den verschiedenen Mehrkomponentenverbindungen.
Particle-based assays are becoming versatile analytical tools due to their cost-effectiveness, speed, straightforward and diverse functionalization chemistries, especially when polystyrene particles are used. The introduction of functional groups (–COOH, –NH2, etc.) to the surface of such polystyrene particles promotes their application in bioanalytics. However, the traditional method to determine the amount of surface carboxylate groups is conductivity titration, which is usually time- and resources-consuming and discontinuous. Here, we synthesized polystyrene microparticles with different contents of carboxylate groups, and then investigated a simpler and potentially continuous approach to determine the amount of surface carboxylate groups by Zeta potential measurements. The results were compared to the traditional titration method and to actual coupling efficiencies of the functionalized particles with a model oligonucleotide probe as determined by flow cytometry. All quantification methods revealed good agreement.
Two sets of polystyrene nanoparticles (PSNPs) with comparable core sizes but different carboxyl group densities were made and separated using asymmetric flow field flow fractionation (AF4), capillary electrophoresis (CE), and the off-line hyphenation of both methods. Our results revealed the significant potential of two-dimensional off-line AF4-CE hyphenation to improve the separation and demonstrated for the first time, the applicability of CE to determine the functional group density of nanoparticles (NPs). Compared to the result acquired with conductometric titration, the result obtained with synthesized 100 nm sized PSNPs revealed only a slight deviation of 1.7%. Commercial 100 nm sized PSNPs yielded a deviation of 4.6 %. For 60 nm sized PSNPs, a larger deviation of 10.6 % between both methods was observed, which is attributed to the lower separation resolution.
The successful off-line coupling of asymmetrical flow field flow fractionation (AF4) and capillary electrophoresis (CE) for separation of nanoparticles (NPs) with different surface coatings was shown. We could successfully demonstrate that, in a certain NP size range, hyphenation of both techniques significantly improved the separation of differently coated NPs. Three mixtures of polystyrene nanoparticles (PS-NPs) with comparable core sizes but different coatings (no coating/carboxyl-coated) were studied. Separation in either method resulted in non-baseline resolved or non-separated peaks. In contrast, two-dimensional off-line coupling of AF4 and CE resulted in clearly separated regions in their 2 D plots in case of 20 and 50 nm particle mixtures, whereas the 100 nm NP mixture could not be separated at all. Various factors affecting the separation like hydrodynamic diameter or SDS concentration were discussed.
To establish the methodical basis for the development and certification of fluorescence quantum yield standards, we determined the fluorescence quantum yield Φf of rhodamine 6G (R6G) with two absolute methods with complementary measurement principles, here optical spectroscopy using an integrating sphere setup and pulsed laser photoacoustic spectroscopy (PAS). For the assessment of aggregation- and reabsorption-induced distortions of measured fluorescence quantum yields and procedures for the reliable consideration of such effects, this systematic comparison was performed in ethanol and in water employing different concentrations of R6G. In addition, the relative and absolute fluorescence quantum yields of these solutions were obtained with a calibrated spectrofluorometer and a commercialized integrating sphere setup. Based upon this systematic comparison, experimental advantages and systematic sources of variation were identified for both methods.
During the mineralisation of metal carbonates MCO3 (M = Ca, Sr, Ba, Mn, Cd, Pb) liquid-like amorphous intermediates emerge. These intermediates that form via a liquid/liquid phase separation behave like a classical emulsion and are stabilized electrostatically. The occurrence of these intermediates is attributed to the formation of highly hydrated networks whose stability is mainly based on weak interactions and the variability of the metal-containing pre-critical clusters. Their existence and compositional freedom are evidenced by electrospray ionization mass spectrometry (ESI-MS). Liquid intermediates in non-classical crystallisation pathways seem to be more common than assumed.
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.
The therapeutic dose of lithium (Li) compounds, which are widely used for the treatment of psychiatric and hematologic disorders, is close to its toxic level; therefore, drug monitoring protocols are mandatory. Herein, we propose a fast, simple, and low-cost analytical procedure for the traceable determination of Li concentration in human serum, based on the monitoring of the Li isotope dilution through the partially resolved isotope shift in its electronic transition around 670.80 nm using a commercially available high-resolution continuum source graphite furnace atomic absorption spectrometer. With this technique, serum samples only require acidic digestion before analysis. The procedure requires three measurements—an enriched 6Li spike, a mixture of a certified standard solution and spike, and a mixture of the sample and spike with a nominal 7Li/6Li ratio of 0.82. Lanthanum has been used as an internal spectral standard for wavelength correction. The spectra are described as the linear superposition of the contributions of the respective isotopes, each consisting of a spin-orbit doublet, which can be expressed as Gaussian components with constant spectral position and width and different relative intensity, reflecting the isotope ratio in the sample. Both the spectral constants and the correlation between isotope ratio and relative band intensity have been experimentally obtained using commercially available materials enriched with Li isotopes. The Li characteristic mass (mc) obtained corresponds to 0.6 pg. The procedure has been validated using five human serum certified reference materials. The results are metrologically comparable and compatible to the certified values. The measurement uncertainties are comparable to those obtained by the more complex and expensive technique, isotope dilution mass spectrometry.
Three methods for direct solid sampling of bulk material namely IR laser ablation, glow discharge and spark OES, were compared with respect to analytical figures of merit obtained for elemental analysis with atomic spectrometry. Matrices investigated were copper, pressed doped copper powder, and magnesium alloys. For the vast majority of analytes, statistical equivalence regarding precision (usually ≤ 5%) and the performance of the calibrations between the compared methods was demonstrated.
Matrix-assisted laser desorption/ionization-timeof-flight (MALDI-TOF) imaging of polystyrenes with various molecular masses was applied to study spatial molecular mass distribution of polymers in sample spots prepared by the 'dried droplet' method. When different solvents and target surfaces were examined, a segregation of single homologous polymers was observed depending upon the evaporation rate of the solvent. For the observed Patterns left by the evaporating droplet, a hypothesis is offered taking into account different hydrodynamic interactions and diffusion.
The results illustrate that spot preparation using the conventionally 'dried droplet' method is prone to artifacts and should be avoided for reliable and reproducible MALDI mass spectrometry experiments with regards to the Determination of molecular masses and mass distributions.
An ionization scheme for fast online mass spectrometric interrogation of levitated droplets is presented. That renewed method comprises the output of an a Er:YAG laser at λ = 2.94 µm which is in resonance with the OH stretch vibration band of solvents like water and alcohols. A temporal pulse width larger than the time needed for pressure redistribution and also above the temperature redistribution time constant was found to lead to soft evaporation/ionization. Despite these mild desorption conditions, no additional postionization is found to be needed. Accordingly, the ionization is found to be very soft resulting in entirely intact analyte ions and concentration dependent cluster ions. Resulting mass spectra of small amino acids and large antibiotics are presented showing the versatility of the introduced technique. Above a critical mass of m ≈ 1 kDa, the formed ions carry multiple charges as it is typical for thermospray or electrospray ionization. The detection technique enables fast contactless analysis of the chemical composition of levitated microreactors and, thus, paves the way for future contactless reaction monitoring.
Triacetone triperoxide (TATP), an improvised explosive, is a potential security threat because of its cost-efficient synthesis and the difficulty in detecting it. A highly selective antibody could provide the necessary specificity to the detection process. To obtain antibodies, a hapten made from acetone, hydrogen peroxide, and 7-oxooctanoic acid has been designed, synthesized, and confirmed by NMR that displays the utmost similarity to the analyte. The single-crystal X-ray structures of the solvated species TATP·methanol (1:1) and the TATP derivate were determined. In both compounds, the molecules exhibit D3 symmetry and adopt a twisted boat-chair conformation. The hapten was coupled to bovine serum albumin, and mice were immunized. An immune response against TATP was elicited, and selective antibodies were detected in the mouse serum, which should be very useful for the development of a TATP biosensor system. An ELISA with a limit of detection for TATP of 65 µg L-1 is shown.
Triacetone triperoxide (TATP) is a primary explosive, which was used in various terrorist attacks in the past. For the development of biosensors, immunochemical µ-TAS, electronic noses, immunological test kits, or test strips, the availability of antibodies of high quality is crucial. Recently, we presented the successful immunization of mice, based on the design, synthesis, and conjugation of a novel TATP derivative. Here, the long-term immunization of rabbits is shown, which resulted in antibodies of extreme selectivity and more than 1,000 times better affinity in relation to the antibodies from mice. Detection limits below 10 ng L-1 (water) were achieved. The working range covers more than four decades, calculated from a precision profile. The cross-reactivity tests revealed an extraordinary selectivity of the antibodies—not a single compound could be identified as a relevant cross-reactant. The presented immunoreagent might be a major step for the development of highly sensitive and selective TATP detectors particularly for security applications.
Solution-doped metal powder pellets as well as aspirated liquids were used as calibration samples to analyze pure copper and zinc certified reference materials (CRMs) by femtosecond laser ablation ICP-MS. It was demonstrated that calibration by copper pellets resulted in relative deviations up to 20%, whereas fs-LA-ICP-MS among copper-based CRMs led to inaccuracies in the same range unless nominal mass fractions were chosen to be <3 mg/kg. Calibration by zinc pellets generally provided better accuracy. Depending on the analyte considered, deviations below 10% were obtained even for mass fractions close to the limit of quantification. Our data, therefore, indicate solution-doped metal powder pellets to be suitable as calibration samples for fs-LA-ICP-MS of metals. Furthermore, the utilization of liquid standards for calibration was found to result in stronger deviations of up to 50% for both copper and zinc samples which, in addition, turned out to be dependent on the plasma conditions.
In this work, different calibration strategies for the determination of trace elements in pure copper metal by nanosecond laser ablation ICP-MS were investigated. In addition to certified reference materials (CRMs), pellets of doped copper powder were used for calibration. The micro homogeneity of the CRMs as well as the solution-doped pellets was sufficient to use them as calibration samples in combination with a laser spot size of 200 µm. In contrast, pellets doped with analytes in solid form showed a significant heterogeneity. For most of the investigated analytes and copper CRMs the measured mass fractions were within ± 20% of their certified values when other copper CRMs were used as calibration samples. When solution-doped powder pellets were used as calibration samples a systematic trend towards mass fractions below the certified values was observed for nearly all elements determined in the analysed CRMs. Thermal fractionation effects during the ablation of the solution-doped pellets were suspected as the extent of the fractionation depends on the irradiance, whereas fractionation is reduced at higher irradiance.
Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) has been proposed several years ago as an approach for quantitative analysis of Laser-Induced Breakdown Spectroscopy spectra. Recently developed refinement of the spectral processing method is described in the present work. Accurate quantitative results have been demonstrated for several metallic alloys. However, the degree of accuracy that can be achieved with Calibration-Free Laser-Induced Breakdown Spectroscopy analysis of generic samples still needs to be thoroughly investigated. The authors have undertaken a systematic study of errors and biasing factors affecting the calculation in the Calibration-Free Laser-Induced Breakdown Spectroscopy spectra processing. These factors may be classified in three main groups: 1) experimental aberrations (intensity fluctuations and inaccuracy in the correction for spectral efficiency of a detection system), 2) inaccuracy in theoretical parameters used for calculations (Stark broadening coefficients and partition functions) and 3) plasma non-ideality (departure from thermal equilibrium, spatial and temporal inhomogeneities, optical thickness, etc.). In this study, the effects of experimental aberrations and accuracy of spectral data were investigated, assuming that the analytical plasma is ideal. Departure of the plasma conditions from ideality will be the object of future work. The current study was based on numerical simulation. Two kinds of metallic alloys, iron-based and aluminum-based, were studied. The relative weight of the error contributions was found to depend on the sample composition. For the here-investigated samples, the experimental aberrations contribute to the overall uncertainty on the quantitative results more than theoretical parameters. The described simulation method can be applied to the Calibration-Free Laser-Induced Breakdown Spectroscopy analysis of any other kind of sample.
A reversed phase high performance liquid chromatography coupled to an inductively coupled plasma mass spectrometer (HPLC-ICP-MS) approach in combination with isotope dilution analysis (IDA) for the separation and parallel quantification of nanostructured and ionic silver (Ag) is presented. The main focus of this work was the determination of the ionic Ag concentration. For a sufficient stabilization of the ions without dissolving the nanoparticles (NPs), the eluent had to be initially optimized. The determined Ag ion concentration was in a good agreement with results obtained using ultrafiltration. Further, the mechanism of the NP separation in the HPLC column was investigated. Typical size exclusion effects were found by comparing results from columns with different pore sizes. Since the recovery rates decreased with increasing Ag NP size and large Ag NPs did not elute from the column, additional interactions of the particles with the stationary phase were assumed. Our results reveal that the presented method is not only applicable to Ag NPs, but also to gold and polystyrene NPs. Finally, IDA-HPLC-ICP-MS experiments in single particle mode were performed to determine the particle cut-off size. The comparison with conventional spICP-MS experiments resulted in a similar diameter and particle size distribution.
In this work, sample losses of silver nanoparticles (Ag NPs) in asymmetrical flow field-flow fractionation (AF4) have been systematically investigated with the main focus on instrumental conditions like focusing and cross-flow parameters as well as sample concentration and buffer composition. Special attention was drawn to the AF4 membrane. For monitoring possible silver depositions on the membrane, imaging laser ablation coupled to inductively coupled plasma mass spectrometry (LA-ICP-MS) was used. Our results show that the sample residue on the membrane was below 0.6% of the total injected amount and therefore could be almost completely avoided at low sample concentrations and optimized conditions. By investigation of the AF4 flows using inductively coupled plasma mass spectrometry (ICP-MS), we found the recovery rate in the detector flow under optimized conditions to be nearly 90%, while the cross-flow, slot-outlet flow and purge flow showed negligible amounts of under 0.5%. The analysis of an aqueous ionic Ag standard solution resulted in recovery rates of over 6% and the ionic Ag content in the sample was found to be nearly 8%. Therefore, we were able to indicate the ionic Ag content as the most important source of sample loss in this study.