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)
Research on carbohydrate based interactions with proteins, nucleic acids or antibodies has gained increased interest in the last years especially in clinical diagnosis or drug development. The efficiency of diagnostic interfaces depends upon the number of probe molecules, e.g. carbohydrates. The control of surface parameters as density and distribution of immobilized carbohydrates is essential for a reliable interaction with protein analytes. A controlled production of biomolecular interfaces can be reached by a stepwise quality control during buildup of these biointerfaces.
Here, ß-amino-cyclodextrin molecules were attached to amine-reactive silicon oxide surfaces via click chemistry to construct a model biosensor surface. The amount of surface bound carbohydrates was determined indirectly after chemical derivatization with 4-(trifluoromethyl)-benzylamine (TFMBA). Moreover, these surfaces were used to form host-guest complexes of ferrocene (guest) and β-cyclodextrin (host) moieties to mimic the target binding (sensing) of the model biosensor. Surface chemical analysis of all steps during biosensor construction was performed using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). Our approach widens the possibilities to generate switchable surfaces based on ß-Cyclodextrin surfaces for biosensor applications.
Metal-containing nanoparticles (NP) can be characterized with inductively coupled plasma mass spectrometers (ICP-MS) in terms of their size and number concentration by using the single-particle mode of the instrument (spICP-MS). The accuracy of measurement depends on the setup, operational conditions of the instrument and specific parameters that are set by the user. The transport efficiency of the ICP-MS is crucial for the quantification of the NP and usually requires a reference material with homogenous size distribution and a known particle number concentration.
Currently, NP reference materials are available for only a few metals and in limited sizes. If particles are characterized without a reference standard, the results of both size and particle number may be biased. Therefore, a dual-inlet Setup for characterizing nanoparticles with spICP-MS was developed to overcome this problem. This setup is based on a conventional introduction system consisting of a pneumatic nebulizer (PN) for nanoparticle solutions and a microdroplet Generator (μDG) for ionic calibration solutions. A new and flexible interface was developed to facilitate the coupling of μDG, PN and the ICP-MS system. The interface consists of available laboratory components and allows for the calibration, nanoparticle (NP) characterization and cleaning of the arrangement, while the ICP-MS instrument is still running.
Three independent analysis modes are available for determining particle size and number concentration. Each mode is based on a different calibration principle.
While mode I (counting) and mode III (μDG) are known from the literature, mode II (sensitivity), is used to determine the transport efficiency by inorganic ionic Standard solutions only. It is independent of NP reference materials. The μDG based inlet system described here guarantees superior analyte sensitivities and, therefore, lower detection limits (LOD). The size dependent LODs achieved are less than 15 nm for all NP (Au, Ag, CeO2) investigated.
Among the large number of new ambient ionization schemes in the last few years, dielectric barrier discharge (DBD) has witnessed special attention. In this contribution a versatile dual mode DBD is introduced and characterized by means of optical emission spectroscopy and time-of-flight mass spectrometry. A direct comparison of the individual results from spectroscopy, spectrometry and transient current/voltage consumption gives evidence for the existence of two individual operational mechanisms. The first is driven by rapid transient changes in the potential difference between the two electrodes over time (usually denoted as the homogeneous mode), while the second is caused at high static potential differences (leading to filamentary discharges). The transient versus steady-state characteristics of the individual discharge origin suggest the driving force for the current flow to be inductive and capacitive, respectively. In most cases of dielectric barrier plasmas both discharge types coexist as competitive ion formation channels, however, detailed plasma characteristics of DBDs operated under different conditions allow for a clear distinction of the individual contributions. In this way, two characteristic product channels for the ionization of ambient water could be observed resulting in the generation of either preferentially protonated water clusters or ammonium water clusters. Careful tuning of the operation parameters of the discharge device allows an operation predominated by either of the two modes. As a consequence, facile switching into the desired operational mode results in either protonated molecules or ammoniated molecules of the analyte. Plasma characteristics for both moieties were evaluated and cross-correlated on the basis of several factors including: the production of reagent ions, the individual appearance of current/voltage profiles, UV/Vis spectroscopy, voltage and flux dependence and the individual response to test compounds. Although the filamentary mode has been already discussed in the literature to induce fragmentation processes, no experimental evidence for analyte dissociation could be found in the case of the test compounds used
Biotransformation processes of fluopyram (FLP), a new succinate dehydrogenase inhibitor (SDHI) fungicide, were investigated by electrochemistry (EC) coupled online to liquid chromatography (LC) and electrospray mass spectrometry (ESI-MS). Oxidative phase I metabolite production was achieved using an electrochemical flow-through cell equipped with a boron doped diamond (BDD) electrode. Structural elucidation and prediction of oxidative metabolism pathways were assured by retention time, isotopic patterns, fragmentation, and accurate mass measurements using EC/LC/MS, LC-MS/MS, and/or high resolution mass spectrometry (HRMS). The results obtained by EC were compared with conventional in vitro studies by incubating FLP with rat and human liver microsomes (RLM, HLM). Known phase I metabolites of FLP (benzamide, benzoic acid, 7-hydroxyl, 8-hydroxyl, 7,8-dihydroxyl FLP, lactam FLP, pyridyl acetic acid, and Z/E-olefin FLP) were successfully simulated by EC/LC/MS. New metabolites including an imide, hydroxyl lactam, and 7-hydroxyl pyridyl acetic acid oxidative metabolites were predicted for the first time in our study using EC/LC/MS and liver microsomes. We found oxidation by dechlorination to be one of the major metabolism mechanisms of FLP. Thus, our results revealed that EC/LC/MS-based metabolic elucidation was more advantageous on time and cost of analysis and enabled matrix-free detection with valuable information about the mechanisms and intermediates of metabolism processes.
The improved Monte-Carlo (MC) method for standard-less analysis in laser induced breakdown spectroscopy (LIBS) is presented. Concentrations in MC LIBS are found by fitting model-generated synthetic spectra to experimental spectra. The current version of MC LIBS is based on the graphic processing unit (GPU) computation and reduces the analysis time down to several seconds per spectrum/sample. The previous version of MC LIBS which was based on the central processing unit (CPU) computation requested unacceptably long analysis times of 10's minutes per spectrum/sample. The reduction of the computational time is achieved through the massively parallel computing on the GPU which embeds thousands of co-processors. It is shown that the number of iterations on the GPU exceeds that on the CPU by a factor > 1000 for the 5-dimentional parameter space and yet requires > 10-fold shorter computational time. The improved GPU-MC LIBS outperforms the CPU-MS LIBS in terms of accuracy, precision, and analysis time. The performance is tested on LIBS-spectra obtained from pelletized powders of metal oxides consisting of CaO, Fe2O3, MgO, and TiO2 that simulated by-products of steel industry, steel slags. It is demonstrated that GPU-based MC LIBS is capable of rapid multi-element analysis with relative error between 1 and 10's percent that is sufficient for industrial applications (e.g. steel slag analysis). The results of the improved GPU-based MC LIBS are positively compared to that of the CPU-based MC LIBS as well as to the results of the standard calibration-free (CF) LIBS based on the Boltzmann plot method.
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.
A systematic crystal morphology study on the pharmaceutical model compound caffeine has been conducted on different surfaces: silicon, silver, soda lime glass, and silver subsurface ion-exchanged soda-lime silicate (SIMO) glasses. The morphology of the solid caffeine deposits has been investigated using environmental scanning electron microscopy (ESEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). Needle-shaped caffeine crystals have been observed by drop-casting and also by applying the rapid expansion of supercritical solutions (RESS) technique using supercritical carbon dioxide. The aspect ratio of the crystalline needles typically vary between 10 and 100, but have been observed as large as 500. The XRD data of the RESS products indicate unambiguously the presence of the thermodynamically most stable polymorph of caffeine known as the β-form. Under defined conditions we observe a unique, surface-mediated morphology for caffeine crystals with nearly perfect hexagonal shape. The relative fraction of the hexagons was seen to strongly increase especially when SIMO glasses were used. These hexagons have a distinct upper size limit depending on the solvent and substrate being used. The size distribution analysis of the hexagons yielded an average perimeter of typically 10 µm. The mechanism of the formation process of this new hexagonal motif is explained in terms of the spinodal dewetting of the thin film of caffeine solution on the surface.
The hollow cathode (HC) effect was investigated in non-cooled 15 mm deep drilled flat metallic analytical samples that were easy to prepare. The deep cavity used ("complete HC" in contrast to "recessed HC" with 2-3 mm deep cavity) intensified the HC effect notably and therefore distinctly improved the detection power of the common GD-OES with planar cathodes. A signal enhancement of up to a factor of 150, not reported earlier, in comparison with flat conventional samples was achieved. A better separation of the analytical lines from spectral interferences was observed when the HC assembly was applied. Additionally, an effect of strongly enhanced intensities of atomic lines and somewhat decreased intensities of ionic lines was detected in the case of HC in comparison to usual planar cathodes. The investigations were carried out with samples of copper, steel and zinc matrices using both the same and individually optimised glow discharge (GD) electrical parameters.