Chemie und Prozesstechnik
Filtern
Dokumenttyp
- Zeitschriftenartikel (127) (entfernen)
Schlagworte
- ICP-MS (22)
- Laser ablation (16)
- Nanoparticle (12)
- Traceability (10)
- Imaging (8)
- Cell (7)
- PFAS (7)
- Metrology (6)
- Copper (5)
- Fluorescence (5)
- LA-ICP-MS (5)
- Uncertainty (5)
- Absolute isotope ratio (4)
- Calibration (4)
- HR-CS-GFMAS (4)
- Immunohistochemistry (4)
- Isotope dilution (4)
- Magnetic resonance imaging (4)
- Mass spectrometry (4)
- Measurement uncertainty (4)
- Brain (3)
- Cement (3)
- Extractable organically bound fluorine (EOF) (3)
- High resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) (3)
- Human serum (3)
- Isotope ratio (3)
- Isotope ratios (3)
- LC-MS/MS (3)
- MC-ICP-MS (3)
- Nanoparticles (3)
- Reference material (3)
- Sulfur (3)
- Affinity chromatography (2)
- Analytical Chemistry (2)
- Bioconjugation (2)
- Bioimaging (2)
- Cancer (2)
- Cells (2)
- Comparability (2)
- Contrast agent (2)
- Delta scale (2)
- Delta value (2)
- Diatoms (2)
- Editorial (2)
- Environmental speciation (2)
- Fluorine (2)
- Gadolinium (2)
- General Earth and Planetary Sciences (2)
- ICP-ToF-MS (2)
- Interlaboratory comparison (2)
- Iron (2)
- Isotope dilution mass spectrometry (2)
- Isotope reference material (2)
- Isotopic fractionation (2)
- Lithium (2)
- MRI (2)
- Mercury (2)
- Metals (2)
- Metrology in chemistry (2)
- Molar mass (2)
- Nanomaterials (2)
- Nickel (2)
- Peptide (2)
- Peptide library (2)
- Per- and polyfluorinated alkyl substances (PFASs) (2)
- Purity (2)
- Quantification (2)
- SI (2)
- SI traceability (2)
- SPM (2)
- Single particle ICP-MS (2)
- Solid-liquid extraction (2)
- Sr isotopes (2)
- Triple isotope fractionation (2)
- 150th anniversary (1)
- 3D ultrastructural analysis (1)
- 6xHis (1)
- AAS (1)
- ABC (1)
- AF4 (1)
- ATCUN (1)
- Absorption spectrometry (1)
- Adsorbable organically bound fluorine (AOF) (1)
- Adsorption (1)
- Affinity (1)
- Affinity extraction (1)
- Alanine scan (1)
- Albumin (1)
- Algorithms (1)
- Aluminum oxide (1)
- Alzheimer’s disease (1)
- Amyloid-beta (1)
- Analysis (1)
- Analytical chemistry (1)
- Analytical sciences (1)
- Anemia (1)
- Antifouling biocides (1)
- Antifouling-Biozide (1)
- Antikensammlung Berlin (1)
- App (1)
- Argon (1)
- Array (1)
- Arsenite (1)
- Atomic Absorption Spectrometry (1)
- Atomic Force Microscopy (1)
- Atomic absorption spectrometry (1)
- Atomic weight (1)
- Automated system (1)
- Avogadro constant (1)
- BAM (1)
- Bacterial lysates (1)
- Binding molecule (1)
- Bioapatite (1)
- Biodiesel fuel (1)
- Biogenic carbonates (1)
- Biological boron recycling (1)
- Bioseparation (1)
- Boron isotope (1)
- Boron isotope fractionation (1)
- Boron isotopic composition (1)
- Brassica napus (1)
- Bundesanstalt für Materialforschung und -prüfung (1)
- Böden (1)
- CCQM (1)
- CE/MC-ICP-MS (1)
- CIC (1)
- CRM (1)
- Calcification (1)
- Calcium (1)
- Calcium monofluoride (1)
- Capillary electrophoresis-mass spectrometry (1)
- Carbodiimide crosslinking (1)
- Carrier (1)
- Cconventional method (1)
- Cellular trafficking (1)
- Central Taurus (1)
- Certification (1)
- Chelate (1)
- Chemometrie (1)
- Chemometrik (1)
- Chenopodium album (1)
- Chicken antibodies (1)
- Chromatography (1)
- Ciaaw.org (1)
- Classical primary measurement method (CPM) (1)
- Cleaning (1)
- Climate (1)
- Cluster (1)
- Collection (1)
- Combinatorial chemistry (1)
- Combustion Ion Chromatography (1)
- Combustion ion chromatography (CIC) (1)
- Complementary MS (1)
- Comsumer good samples (1)
- Confocal laser scanning microscopy (1)
- Conventional isotope ratio (1)
- Corophium volutator (1)
- Cryo-soft X-ray tomography (1)
- Cytoplasm (1)
- Cytoplasmic remodeling (1)
- Data processing (1)
- Degradation (1)
- Delta isotope standard (1)
- Dendritic polyglycerol sulfate (1)
- Diagenesis (1)
- Diagnostics (1)
- Diatomeenanalytik (1)
- Diffusion (1)
- Digestion (1)
- Dip-stick assay (1)
- Direct metal assay (1)
- Dissolution (1)
- Docking (1)
- Downstream processing (1)
- Dyes/pigments (1)
- EDTAD (1)
- ELISA (1)
- EPMA (1)
- Early Earth (1)
- Ecotoxicity (1)
- Ecotoxicological Testing (1)
- Ecotoxicology testing (1)
- Einzelzellanalyse (1)
- Elemental analysis (1)
- Elemental composition (1)
- Elemental fingerprints (1)
- Environment (1)
- Environmental pollution monitoring (1)
- Escherichia coli (1)
- Ethylenediaminetetraacetic acid (1)
- Exposure (1)
- Extracellular matrix (1)
- Extrahierbar organisch gebundenes Fluor (EOF) (1)
- Fe nanoparticles metabolism (1)
- Fertilizer (1)
- Finow Canal (1)
- Fluor (1)
- Fluorescence label (1)
- Fluorination (1)
- Fluorophilic interactions (1)
- GD-MS (1)
- GD-OES (1)
- GDMS (1)
- GF-MAS (1)
- Gadolinium-based contrast agents (GBCAs) (1)
- Geochemistry (1)
- Geochemistry and Petrology (1)
- Geological material (1)
- Geophysics (1)
- Glycosaminoglycan (1)
- Graphite furnace (1)
- Greek curse tablets (1)
- Group profile (1)
- HF free Digestion (1)
- HPLC-ICP-MS (1)
- HR-CS-MAS (1)
- Hafnium (1)
- Heat flow (1)
- HexaHis-Tag (1)
- High pH (1)
- High pressure experiments (1)
- High-fired gypsum mortar (1)
- High-purity elements (1)
- High-resolution continuum source graphite furnace atomic absorption spectrometry (1)
- His6 (1)
- His8 (1)
- Hot-pressing (1)
- Hydrated silicate melts (1)
- Hydrodynamic chromatography (HDC) (1)
- Hydrogen (1)
- Hydrolysis products (1)
- Hydrothermal fluid (1)
- Hyphenated (1)
- ICP (1)
- ICP-MS/MS (1)
- ICP-TOF-MS (1)
- ICP-TOFMS (1)
- IDMS (1)
- ILC (1)
- IMAC purification (1)
- IgY (1)
- Iinductively coupled plasma mass spectrometry (1)
- Immunoaffinity extraction (1)
- Immunocapture (1)
- Immunofluorescence (1)
- Immunology (1)
- Impurity assessment (1)
- In situ (1)
- In vitro (1)
- In-house calibration solution (1)
- Industrielle Analytik (1)
- Inflammation (1)
- Inorganic chemical analysis (1)
- Instrumental isotope fractionation (1)
- Iposomes (1)
- Iridium (1)
- Iron nanoparticles (1)
- Iron oxide (1)
- Isotope (1)
- Isotope Dilution (1)
- Isotope amount ratio (1)
- Isotope delta (1)
- Isotope delta value (1)
- Isotope fractionation (1)
- Isotopes (1)
- Isotopic analysis (1)
- Isotopic dilution (1)
- Jahrestag (1)
- Kapillarelektrophorese-Massenspektrometrie (1)
- Kidney (1)
- Kilogram (1)
- Komplementäre Massenspektrometrie (1)
- Kristallolgraphie (1)
- LA-(MC-)ICP-MS (1)
- LA/ICP-MS Imaging (1)
- LSVEC (1)
- Lab-on-a-chip (1)
- Labeling (1)
- Lanthanide (1)
- Laser (1)
- Laser Ablation (1)
- Laser Ablation/Imaging (1)
- Laser ablation inductively coupled plasma–mass spectrometry imaging (LA-ICP-MSI) (1)
- Lead (1)
- Lead isotope composition (1)
- Lead isotope ratios (1)
- Lead isotope variations (1)
- Lead isotopes (1)
- Legacy pollution (1)
- Life sciences (1)
- Limit of detection (1)
- Lymnaea stagnalis (1)
- MALDI-TOF MS (1)
- MC-TIMS (1)
- MST (1)
- Machine learning (1)
- Magnesium (1)
- Magnesium isotope ratios (1)
- Mass cytometry (1)
- Massenspektrometrie (1)
- Material sciences (1)
- Matrix-assisted laser desorption ionization–mass spectrometry imaging (MALDI-MSI) (1)
- Measuremment uncertainty (1)
- Medicinal application (1)
- Mercury speciation (1)
- Mesoporous materials (1)
- Metal nanoclusters (1)
- Metal toxicity (1)
- Metal uptake (1)
- Metalloprotein (1)
- Method (1)
- Methylmercury (1)
- Metrology in Chemistry (1)
- Micro-sublimation (1)
- Microdroplet generator (1)
- Microplastic-induced effects (1)
- Microplatic (1)
- Mixture toxicity (1)
- Mobile phase (1)
- Mole (1)
- Molecular imaging (1)
- Multi-collector inductively coupled plasma-mass spectrometry (ICP-MS) (1)
- Multielementanalytik (1)
- Multielementanalytik in kurzen transienten Signalen (1)
- Multimodal (1)
- Multimodale Analytik (1)
- Multiple sclerosis (1)
- Multiple-injection sample-standard bracketing (1)
- Nano-carrier (1)
- Nanocluster (1)
- Nanoparticle characterization (1)
- Nanopartikel (1)
- Nickel chelate (1)
- Nitrogen microwave inductively coupled atmospheric pressure mass spectrometry (1)
- Non-metal analysis (1)
- Non-target (1)
- OBOC library (1)
- Oberflächengewässer (1)
- Oberflächenwasser (1)
- On-chip screening (1)
- On-line CE/MC-ICP-MS (1)
- One-bead-one-compound library (1)
- Ore provenance (1)
- Oxygen evolution reaction (1)
- Oxygen isotope ratios (1)
- Pb isotopes (1)
- Peptide aptamers (1)
- Peptides and Proteins (1)
- Per- and Polyfluoroalkyl substances (PFAS) (1)
- Per- and polyfluorinated alkly substances (PFASs) (1)
- Photocatalysis (1)
- Plant tissue (1)
- Polarised light microscopy (1)
- Polishing (1)
- Pollutant (1)
- Pollution (1)
- Polyethylenimine (1)
- Polymer membrane (1)
- Pore fluids (1)
- Portland cement (1)
- Portland clinker (1)
- Priam's treasure (1)
- Primary calibration solution (1)
- Primary difference measurement method (PDM) (1)
- Primary transfer standards (PTSs) (1)
- Programmed cell death (1)
- Protein imaging (1)
- Provenance (1)
- Provenancing (1)
- Prozessanalytik (1)
- Prozessindustrie (1)
- Pt-based drugs (1)
- PtNP (1)
- Purity assessment (1)
- Quality assurance (1)
- Quantitative protein analysis (1)
- Radiogenic isotopes (1)
- Raman microspectroscopy (1)
- Raman spectroscopy (1)
- Recombinant protein (1)
- Reference (1)
- Reference Materials (1)
- Reference measurements (1)
- Remediation (1)
- Revision of the SI (1)
- River water (1)
- River water sulfate (1)
- SC-ICP-MS (1)
- SERS (1)
- SI-traceability (1)
- SPR (1)
- Sample-sample bracketing (1)
- Sapphire (1)
- Scale anchor (1)
- Scale conversion (1)
- Schwebstoffe (1)
- Seawater (1)
- Sediment (1)
- Selenium (1)
- Sensor (1)
- Serum (1)
- Sewage sludge (1)
- Silbernanopartikel (1)
- Silica diagenesis (1)
- Silicon (1)
- Silicon isotopes (1)
- Single Cell (1)
- Single cell analysis (1)
- Single cell-ICP-MS (1)
- Single cell-ICP-ToF-MS (1)
- Single-cell analysis (1)
- Soil (1)
- Soil available boron (1)
- Soils (1)
- Solid phase extraction (SPE) (1)
- Spark plasma sintering (1)
- Special issue (1)
- Special issue, young analytical scientists (1)
- Speciation analysis (1)
- Species-unspecific on-line isotope dilution (1)
- Spectrometer (1)
- Speroid (1)
- Spheroid (1)
- Sputtering (1)
- Sr and Nd isotope analysis (1)
- Sr isotope analysis (1)
- Stability (1)
- Stable isotopes (1)
- Standard atomic weight (1)
- Standardization (1)
- Statistical analysis (1)
- Strontium isotope (1)
- Sulfur isotopes (1)
- Sulphur isotope (1)
- Sum parameter (1)
- Surface plasmon resonance (1)
- Surface water (1)
- Surface waters (1)
- Synthetic peptides (1)
- Tantalum oxyfluorides (1)
- Tau (1)
- Test strips (1)
- Tetramethylammonium hydroxide (1)
- Thin tissue sections (1)
- Tissue (1)
- Tissue soldering (1)
- Titanium hydride (1)
- Total element content (1)
- Total element determination (1)
- Toxic elements (1)
- Toxicity (1)
- Transferrin (1)
- Transient signal (1)
- Trojan silver artefacts (1)
- Two-phase system (1)
- Umwelt-Speziation (1)
- Validation (1)
- WWTP (1)
- XRCD method (1)
- Xerogel (1)
- Ytterbium (1)
- Zinc (1)
- Zirconium (1)
- bell pepper (1)
- boron (1)
- delta value (1)
- isotope fractionation (1)
- lank characterization (1)
- measurement uncertainty (1)
- metabolism (1)
- silicon (1)
- spICP-MS (1)
- species-specific isotope information (1)
- tandard addition (1)
- Ägyptisches Museum Berlin (1)
- β-lactam (1)
Organisationseinheit der BAM
- 1.1 Anorganische Spurenanalytik (127) (entfernen)
Paper des Monats
- ja (3)
Lead isotope amount ratios are commonly used in diverse fields such as archaeometry, geochemistry and forensic science. Currently, five reference materials with certified lead isotope amount ratios are available, namely NIST SRM 981, 982 and 983, GBW-04442 and NMIJ 3681-a. Only NIST SRM 981 and NMIJ 3681-a have approximately natural isotopic compositions, and NIST SRM 981 is predominantly used for correcting mass discrimination/mass fractionation in the applied mass spectrometric procedures. Consequently, there is no other certified reference material available to be used for validation and/or quality control of the analytical procedures applied to lead isotope amount ratio measurements. To fill this gap, two new reference materials have been produced and certified for their lead isotope amount ratios. For both certified reference materials, complete uncertainty budgets have been calculated and SI traceability has been established. This provides the users with independent means for validating and verifying their analytical procedures and for conducting quality control measures. ERM-EB400 is a bronze material with a nominal lead mass fraction of 45 mg kg-1 and certified lead isotope amount ratios of n(206Pb)/n(204Pb) = 18.072(17) mol mol-1, n(207Pb)/n(204Pb) = 15.578(18) mol mol-1 and n(208Pb)/n(204Pb) = 38.075(46) mol mol-1 with the associated expanded uncertainties (k = 2) given in brackets. ERM-AE142 is a high-purity solution of lead in 2% nitric acid with a nominal mass fraction of 100 mg kg-1 and certified Pb isotope amount ratios of n(206Pb)/n(204Pb) = 21.114(17) mol mol-1, n(207Pb)/n(204Pb) = 15.944(17) mol mol-1 and n(208Pb)/n(204Pb) = 39.850(44) mol mol-1 with the associated expanded uncertainties (k = 2) given in brackets. Both materials are specifically designed to fall within the natural lead isotopic variation and to assist users with the validation and verification of their analytical procedures. Note that while one of these reference materials requires the chemical separation of Pb from its matrix (ERM-EB400), the other does not (ERM-AE142). As additional information, δ208/206PbNIST SRM981 values are provided for both materials. For ERM-AE142, a delta value of δ208/206PbNIST SRM981 = -28.21(30) ‰ was obtained, and for ERM-EB400, a delta value of δ208/206PbNIST SRM981 = -129.47(38) ‰ was obtained, with the associated expanded uncertainties (k = 2) given in brackets.
Complementarity of molecular and elemental mass spectrometric imaging of Gadovist™ in mouse tissues
(2019)
Drug biodistribution analyses can be considered a key issue in pharmaceutical discovery and development. Here, mass spectrometric imaging can be employed as a powerful tool to investigate distributions of drug compounds in biologically and medically relevant tissue sections. Both matrix-assisted laser desorption ionization–mass spectrometric imaging as molecular method and laser ablation inductively coupled plasma–mass spectrometric imaging as elemental detection method were applied to determine drug distributions in tissue thin sections. Several mouse organs including the heart, kidney, liver, and brain were analyzed with regard to distribution of Gadovist™, a gadolinium-based contrast agent already approved for clinical investigation. This work demonstrated the successful detection and localization of Gadovist™ in several organs. Furthermore, the results gave evidence that gadolinium-based contrast agents in general can be well analyzed by mass spectrometric imaging methods. In conclusion, the combined application of molecular and elemental mass spectrometry could complement each other and thus confirm analytical results or provide additional information.
Metal tags find application in a multitude of biomedical systems and the combination with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) offers an opportunity for multiplexing. To lay the foundation for an increase of the signal intensities in such processes, we herein present a general approach for efficient functionalization of a well-defined metal oxido cluster [Bi6O4(OH)(4)(SO3CF3)(6)(CH3CN)(6)].2 CH3CN (1), which can be realized by selecting 7mer peptide sequences via combinatorial means from large one-bead one-compound peptide libraries. Selective cluster-binding peptide sequences (CBS) for 1 were discriminated from non-binders by treatment with H2S gas to form the reduction product Bi2S3, clearly visible to the naked eye. Interactions were further confirmed by NMR experiments. Extension of a binding peptide with a maleimide linker (Mal) introduces the possibility to covalently attach thiol-bearing moieties such as biological probes and for their analysis the presence of the cluster instead of mononuclear entities should lead to an increase of signal intensities in LA-ICP-MS measurements. To prove this, CBS-Mal was covalently bound onto thiol-presenting glass substrates, which then captured 1 effectively, so that LA-ICP-MS measurements demonstrated drastic signal amplification compared to single lanthanide tags.
Boron (B) is an essential micronutrient for plant growth. Lack of valid methods for pretreatment and measurement of δ11B in plant restrict applications of it in the biosphere. Dry ashing, one step cation exchange and micro-sublimation were combined to separate and purify boron (B) in plant tissues. The low procedure blank, high B recovery and the accurate δ11B values of the plant reference materials demonstrate that this method is suitable and valid for B pretreatment and δ11B measurement in plant samples by MC-ICP-MS. Based on this method, the δ11B in different plants (Brassica napus, Chenopodium album L, moss, lichen, and Nostoc commune) was analyzed. For Brassica napus, δ11B increased gradually from root to leaf, and then decreased to rapeseed. For the same parts, the δ11B increased from the lower parts to the higher parts. This variation may be due to the B(OH)3 transporter of NIP6;1 and the incorporation of B into the cell. The reason for lower δ11B values in shell and rapeseed compared to those in leaves presumably is to the preferred Transport of borate in the phloem. The largest δ11B fractionation between leaf and root in Brassica napus and Chenopodium album L was +24.2‰ and +26.6‰, respectively. The large variation and fractionation of δ11B within plants indicates that δ11B is a good tracer to study the B translocation mechanisms and metabolism within plants. The δ11B in Nostoc commune, lichen, and moss showed variations of -4.1‰ to +21.5‰, −9.4‰ to +7.3‰, and −18.3‰ to +11. 9‰, respectively. In the same site, δ11B in different plants ranked Nostoc commune>moss>lichen and δ11B in mosses growing in different environment ranked soil>tree>rock. Rain and soil available B are the main B sources for these plants. The δ11B in Nostoc commune, lichen, and moss may be a useful tracer to study the atmospheric B input. In the future, plants culture experiments under certain environments and studies from molecular level are necessary to decipher the variation of δ11B and fractionation mechanisms within plants.
Invited for this month’s cover picture is the group of Dr. Knut Rurack at the Department of Analytical Chemistry; Reference Materials at the Bundesanstalt fuer Materialforschung und -pruefung (BAM) in Berlin (Germany). The cover picture shows how differences in color and fluorescence on a test strip can be easily read out with a mobile device. Two reference spots Frame the sensitive spot that indicates the presence of trace amounts of HgII below the threshold in a natural water sample. This dipstick contains a hybrid material that combines boron-dipyrromethene (BODIPY) probes sterically loaded into specifically tailored mesoporous silica particles, allowing for ultrasensitive HgII detection through enhanced fluorescence in a few seconds. The applicability in real water samples and fish extracts are also studied.
Recent recommendations by the Food and Drug Administration1 and the European Medicines Agency2 are to limit the clinical use of linear gadolinium-based contrast agents (GBCAs) due to convincing evidence of deposition in tissues. Macrocyclic GBCA continued to be considered safe, provided that patients have normal renal function. To date, given the low sensitivity of conventional MRI, there has been a debate about the signal increase following the injections of a macrocyclic GBCA.
In this paper, we describe the labelling of antibodies by gold nanoparticles (AuNPs) with diameters of 10 and 60 nm with detection by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Additionally, the AuNPs labelling strategy is compared with commercially available labelling reagents based on MeCAT (metal coded affinity tagging). Proof of principle experiments based on dot blot experiments were performed. The two labelling methods investigated were compared by sensitivity and limit of detection (LOD). The absolute LODs achieved were in the range of tens of picograms for AuNP labelling compared to a few hundred picograms by the MeCAT labelling.
Iron nanoparticles (NPs) metabolism is directly associated to human health due to their use as anemia treatment and should be studied in detail in cells. Here we present a speciation strategy for the determination of the metabolic products of iron oxide nanoparticles coated by tartaric and adipic acids in enterocytes-like cell models (Caco-2 and HT-29). Such methodology is based on the use of SDS-modified reversed phase high performance liquid chromatography (HPLC) separation using inductively coupled plasma-mass spectrometry (ICP-MS) as Fe selective detector. Post-column isotope dilution analysis is used as quantification tool by adding Fe-57 as isotopically enriched standard. To assess the separation capability of the method, two different iron nanostructures: iron sucrose nanoparticles -Venofer®- used as model suspension and iron tartrate/adipate-modified nanoparticles, both of about 4 nm (core size) were evaluated. The two nanostructures were injected into the system showing good peak profiles and quantitative elution recoveries (>80%) in both cases. In addition, both nanoparticulate fractions could be based-line separated from ionic iron species, which needed to be complexed with 1mM citrate to elute from the column. Exposed cells up to 0.5mM of iron tartrate/adipate-modified nanoparticles were specifically treated to extract the internalized NPs and the extracts examined using the proposed strategy. The obtained results revealed the presence of three different fractions corresponding to nanoparticle aggregates, dispersed nanoparticles and soluble iron respectively in a single chromatographic run. Quantitative experiments (column recoveries ranging from 60 to 80%) revealed the presence of the majority of the Fe in the nanoparticulated form (>75%) by summing up the dispersed and aggregate particles. Such experiments point out the high uptake and low solubilization rate of the tartrate/adipate NPs making these structures highly suitable as Fe supplements in oral anemia treatments.
The mechanism of action of zirconium permanent modifiers on graphite surfaces was investigated in order to understand its influence on the analytical signal in atomic and molecular absorption spectrometry (AAS/MAS). For this, the molecule formation of CaF was studied, which is used for the indirect analytical determination of fluorine in high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). The kinetics of this reaction was established by monitoring its molecular spectrum at different atomisation temperatures. An Arrhenius plot showed a pseudo-first order reaction with respect to fluorine (n = 1). An intermediate state was isolated, and its structure was elucidated by spectroscopic methods: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEMEDX), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XANES and EXAFS), and Raman microspectroscopy. We propose here a mechanism, where ZrO2 acts as a heterogeneous catalyst: after a pyrolytic step, an intermediate state of ZrO(OCaF) is activated, and at higher temperatures, CaF(g) is released from the zirconium-coated graphite surface. No evidence of the formation of zirconium carbide was found. Consequently, as the CaF formation is catalysed by a heterogeneous catalyst, surface modifications with ZrO2 nanoparticles and ZrO xerogels were investigated in order to increase the surface area. Their influence was evaluated in the molecule formation of CaF, CaCl, CaBr, and CaI. Graphite furnace modification with zirconium oxide nanoparticles proves to be the best choice for fluorine analysis with a signal enhancement of more than eleven times with respect a non-coated graphite furnace. However, the influence of zirconium modifications in the analytical signals of Cl, and I is lower than the F signals or even negative in case of the Br. Understanding zirconium modifiers as heterogeneous catalysts offers a new perspective to AAS and MAS, and reveals the potential of surface analytical methods for development of improved permanent modifiers and graphite furnace coatings.
LA-ICP-MS is increasingly used for single cell analysis in two different detection modes using either the imaging mode with subcellular resolution or alternatively single spot analysis of cells with a larger laser spot size. This study compares the analytical figures of merit of both detection modes (signal to noise, precision, accuracy, throughput), as well as ease of operation and data evaluation. Adherent 3T3 fibroblast cells were stained with two metal dyes (mDOTA-Ho, Ir-DNA-intercalator) and several dozen cells were measured using both modes. We found a ten times higher throughput for single spot analysis, which has as well a straightforward data analysis, shortening the total analysis time further. The signal to noise ratio for single spot analysis was found to be slightly better compared to the signal to noise of pixels in imaging. The mean metal intensity per single cell differed by only 10% between both modes and obtained distributions were found to show no statistically significant differences. Using matrix matched calibration based on standards spotted onto nitrocellulose membrane, we achieved detection limits (10s) of 12 fg for Ir and 30 fg for Ho and quantified 57 +/-35 fg Ir and 1192 +/- 707 fg Ho per single cell.
Compared to a conventional ICP-MS measurement of a digest of about 60000 cells, 54% of Ir content and 358% Ho content was found using quantitative LA-ICP-MS. The difference might be a consequence of the two metal dyes binding to different structures of the cell and therefore might behave differently in sample preparation for conventional and LA-ICP-MS.