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Eingeladener Vortrag
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Within the framework of a German government project (initiated by the Federal Environment Agency) to check the compliance of commercially available batteries with the German Battery Ordinance concerning their heavy metal contents, 18 different types of commercially available zinc-air button cells were analysed for their cadmium, lead and mercury contents. After microwave assisted dissolution with aqua regia, Cd and Pb were determined using inductively coupled plasma mass spectrometry (ICP-MS), and Hg was determined using inductively coupled plasma optical emission spectrometry (ICP OES) and atomic absorption spectrometry. Cd contents were found to be much lower than the permitted limits; Pb contents were also found to be below the limits. Hg contents were found to be near the limits, and in one case the limit was exceeded.
The objective of this work was to test the compliance of commercially available batteries with the German Battery Ordinance, a project of the German government that was initiated by the Federal Environment Agency. Different types of commercially available dry cells were analysed for their cadmium, lead and mercury contents. The dry cells underwent mechanical pre-treatment, separation of the different components and microwave-assisted digestion before determination of the heavy metals. Mercury is sometimes added to prevent the generation of gaseous hydrogen from the electrochemical process. Lead could be present since it is sometimes used as an alloying element of zinc. Cadmium has no technical importance and is an undesirable impurity. None of the batteries contained higher heavy metal mass fractions than the permissible limits.
An intercomparison study of analytical methods for the determination of magnesium in low alloy steel
(2012)
In an intercomparison study three low alloy steel materials were analyzed on their content of the trace element Mg, and five different analytical techniques were used, namely spark-OES, inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma time of flight mass spectrometry (ICP-TOFMS), inductively coupled plasma quadrupole mass spectrometry (ICP-QMS), and glow discharge mass spectrometry (GD-MS). Solid steel discs were used for analysis with spark-OES and GD-MS. For the analyses with ICP-OES, ICP-TOFMS, and ICP-QMS steel chips were wet-digested in aqua regia, and the wet-digestion was performed either in polypropylene tubes placed in a heating block or in Teflon pressure vessels using a microwave assisted system. The Mg concentrations obtained for the three steel materials were: 2.0, 2.8, and 10.3 µg g-1, respectively, and the spread in results was acceptable, giving RSD values in the range of 2030%.
We have developed a very fast and entirely gas-phase based purification technique for carbon nanotubes (CNT) that allows removing metal and metal oxide impurities with high effectiveness. CNT agglomerates from chemical vapor deposition (CVD) synthesis which contained carbon encapsulated catalysts were injected into an atmospheric plasma torch. Very high heating rates allow for quasi-instantaneous vaporization of catalyst particles. This way, metal vapors are hyposized to break mechanically instable encapsulations and effuse from incomplete ones faster than thermally induced graphitization stabilizes such particle encapsulations. The ash content of multi-walled (MW) CNT samples was reduced to less than 15% of the initial value within a few milliseconds. Also the metal content of single-walled (SW) CNT agglomerates was significantly reduced. Repeated injection of CNT agglomerates into the plasma torch resulted in higher-purity products of improved structural integrity and increased oxidation resistance.
A candidate material for the use as primary standard for silver determination was characterized with respect to total purity. Except the radioactive elements and He, all possible impurities were considered. Based on glow discharge mass spectrometry, inductively coupled plasma-mass spectrometry and carrier gas hot extraction measurements, the demonstrated total purity and its standard uncertainty is w(Ag) = (99.999 52 ± 0.000 11) %. The purity value and its uncertainty is dominated by the contributions from the measurements of the nonmetallic impurities, namely S, N, C and O.
Inspired by the globule arc technique a new electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP OES) method was developed for the analysis of high-purity copper materials. The performance of the method was investigated for the analytes Ag, Al, As, Bi, Cd, Co, Cr, Fe, Mg, Mn, Ni, P, Pb, S, Sb, Se, Si, Sn, Te, Ti, Zn and Zr. ETV parameters were optimized regarding the release of the analytes, the transport efficiency and the quality of analytical results in terms of precision, trueness and power of detection. The influence of CCl2F2, CHClF2, C2H2F4 and CHF3 as gaseous halogenation modifiers was investigated. A sufficient in situ analyte matrix separation was achieved by using CHF3 as halogenating reagent avoiding a high matrix input from the molten copper sample into the ETV system and the plasma. A complete release from the samples was obtained for all investigated analytes except Se and Te. Acceptable results for the determination of the trace elements Ag, Al, As, Bi, Cd, Co, Cr, Fe, Mg, Mn, Ni, P, Pb, S, Sb, Si, Sn, Ti, Zn and Zr in high-purity copper were achieved. The method includes a preceding sample preparation step of oxidizing the surface of copper samples which results in a significantly enhanced sensitivity. In addition to the calibration with copper samples, the feasibility of the calibration with liquid multi-element solutions was investigated. Except for Ag, Mg and Ni all analytes could be analyzed using aqueous calibration solutions. The trueness of the method was tested by the determination of analyte contents of certified reference materials. Limits of quantification ranging from 0.6 ng g-1 to 29 ng g-1 were achieved. The developed direct solid sampling method is time and cost effective and well suited for the characterization of high-purity copper materials. The method can be automated to a large extent and is applicable for processes accompanying analyses. In contrast to all other investigated trace elements, Se and Te were not released from the matrix at measurable levels under the used conditions. The determination of these elements is still under investigation and will be reported in a succeeding publication.
Millions of measurements are performed each year by liquid based analytical atomic spectrometry to support healthcare, diagnostic tests, environmental monitoring, material assay, product development and safety. Despite the effort to develop absolute methods, most methods still depend on calibration solutions, which are gravimetric mixtures of high purity solvents and high purity (source material) metals or compounds. As in the real world ideal purity does not exist, the impurity of the solvent and the purity of the source material needs to be known. The impurity of a solvent with respect to one analyte can be measured rather easily and with low limits of determination. In contrast the measurement of the purity of the source material, i.e., the mass fraction of the main constituent in a high purity metal, is more difficult to determine. It becomes even more difficult when the source material is not a pure metal but a compound since problems regarding stoichiometry arise additionally. Although the major producers of calibration solutions make a special effort to determine the purity of the source material, the actual purity statement is often incomplete or not demonstrated. The main reason for this situation is the complexity and high effort necessary to fully characterize such a material. This problem holds to a very wide extent also for the primary standards for element determination at the National Metrology Institutes and Designated Institutes (NMIs and DIs). It is the task of the NMIs and DIs to realise and disseminate primary standards for providing traceability to the International System of Units (SI). The primary elemental standards at the NMIs should provide the link to secondary standards produced by commercial producers and other independently prepared standards for element determination. Without such primary standards, elemental calibration solutions may vary and, depending on the uncertainty required, comparability of measurement in time and space results cannot be achieved.
The results of analytical measurements performed with solid-sampling techniques are affected by the distribution of the analytes within the matrix. The effect becomes significant in case of determination of trace elements in small subsamples. In this framework we propose a measurement model based on Instrumental Neutron Activation Analysis to determine the relative variability of the amount of an analyte among subsamples of a material. The measurement uncertainty is evaluated and includes the counting statistics, the full-energy gamma peak efficiency and the spatial gradient of the neutron flux at the irradiation position. The data we obtained in a neutron activation experiment and showing the relative variability of As, Au, Ir, Sb and W among subsamples of a highly pure Rh foil are also presented.
This paper provides an overview about state of the art methods in the field of plasma spectrometry and its application in material science. Different types of plasmas with their special characteristics for various applications are described. Indirect analytical methods involving sample digestion and often also analyte/matrix separation prior to analyzing the samples still represent the most important routine methods. Here, plasma optical emission and mass spectrometry are the most frequently used determination techniques with a wide variety of instruments commercially available. To avoid the risk of analyte loss or of contaminations during an often time consuming and laborious sample preparation, the use of techniques with direct solid sampling is considered an attractive alternative for the analysis of many materials. A survey on applications with a special focus on direct solid sampling techniques such as GDMS, GD-OES, LA-ICPMS, ETV-ICPMS, ETV-ICP-OES, DC-Arc is given. Different possible calibration strategies are discussed.
Fast flow glow discharge mass spectrometry with a Grimm-type ion source providing a high sputter rate was used for the determination of major nonmetallic impurities in magnesium. The analytical signal was found to be strongly influenced by the electrical discharge parameters. For calibration by standard addition, synthetic standard samples were produced in two different ways—namely, by pressing and by sintering doped metal powders. The observed sensitivity of the calibration curves was shown to depend on the particle size of the powder. For the magnesium powders, the mass fractions of oxygen, nitrogen, boron, and silicon were determined to be about 0.01 kg·kg-1 (relative standard deviation approximately 10–20 %), 2,700 mg·kg-1, 150 mg·kg-1, and 300 mg·kg-1, respectively.
Aiming for a round-robin test, a new method for the direct determination of fluorine in niobium oxide has been developed. It is based on the use of high-resolution molecular absorption spectra of calcium mono-fluoride (CaF) generated in the graphite tube, combined with the slurry sampling technique. The absorption measurement was performed at the 606.44 nm CaF rotational line. By using graphite tubes with zirconium carbide (ZrC) modified platform, the molecular absorption sensitivity of CaF has been improved by a factor of 20, and no additional chemical modifier was necessary. Generally, non-spectral interferences were observed in the presence of HCl, H2SO4, and H3PO4. For HCl, additional spectral interference occurred due to an overlap of the absorption spectra of CaF and CaCl. However, due to the absence of these mentioned substances in the current material, such interferences do not exist for this application. The characteristic mass found for the CaF 606.44 nm line was 0.1 ng; the limit of detection was 5 mg fluorine per kg solid sample (3σ criterion). The results obtained by the method were within the range of certified values. Comparing to the classical method such as the pyrohydrolysis-photometric method, the developed new method showed clear advantages regarding sensitivity and specificity. The time requirement for one sample analysis was strongly shortened from several hours to only some minutes.
Anwendung von Feststoffprobetechniken als Alternative zur Flüssiganalytik: Möglichkeiten und Grenzen
(2010)
Gravimetrically prepared mono-elemental reference solutions having a well-known mass fraction of approximately 1 g/kg (or a mass concentration of 1 g/L) define the very basis of virtually all measurements in inorganic analysis. Serving as the starting materials of all standard/calibration solutions, they link virtually all measurements of inorganic analytes (regardless of the method applied) to the purity of the solid materials (high-purity metals or salts) they were prepared from. In case these solid materials are characterized comprehensively with respect to their purity, this link also establishes direct metrological traceability to The International System of Units (SI). This, in turn, ensures the comparability of all results on the highest level achievable. Several national metrology institutes (NMIs) and designated institutes (DIs) have been working for nearly two decades in close cooperation with commercial producers on making an increasing number of traceable reference solutions available. Besides the comprehensive characterization of the solid starting materials, dissolving them both loss-free and completely under strict gravimetric control is a challenging problem in the case of several elements like molybdenum and rhodium. Within the framework of the European Metrology Research Programme (EMRP), in the Joint Research Project (JRP) called SIB09 Primary standards for challenging elements, reference solutions of molybdenum and rhodium were prepared directly from the respective metals with a relative expanded uncertainty associated with the mass fraction of Urel(w)<0.05 %. To achieve this, a microwave-assisted digestion procedure for Rh and a hotplate digestion procedure for Mo were developed along with highly accurate and precise inductively coupled plasma optical emission spectrometry (ICP OES) and multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) methods required to assist with the preparation and as dissemination tools.
In carrier gas hot extraction the calibration of low amounts of non-metals with masses of a few micrograms with small uncertainty remains a challenge. To achieve high flexibility a high precision gas mixture pump was combined with an automated syringe drive. The gas mixing pump allows filling the syringe with different gas compositions; the automated syringe drive allows matching to modulate the signal profiles to those of real samples. The system was designed and its experimental potential explored. The resulting calibration curves were comparable to those obtained by calibration using solid materials of sufficient purity and stoichiometry. However smaller uncertainties and lower limits of quantification (i.e. 0.5 µg and 0.6 µg for O and N, respectively) were found using the gas calibration device.
Purity statements of high purity materials serving as primary standards by GDMS.
Primary standards are materials known for their total purity and therefore appropriate to realise the link with the International System of Units (SI). The realisation and dissemination of primary standards is of fundamental importance for comparability of measurement results through traceability in all fields of chemical analysis.
To serve as a primary standard for element determination the total purity of a high purity material needs to be measured. In order to achieve a sufficiently small uncertainty (i.e. < 0.01%) this involves determining all possible impurity contributions and to subtract their sum from the ideal purity of 100%.
GD-MS has the potential to reduce the effort for purity determination, as a fast sensitive multi-element analysis without extensive sample preparation. Similar to other solid sampling techniques, glow discharge
requires calibration link the measured signal and the content of the impurities in the matrix.
The use of the concept Relative Sensitivity Factors (RSFs) provides good approximations especially for high purity materials. However, it only works with a wide uncertainty of the results.
The preparation of synthetic pressed powder samples by different modifications of liquid and powder doping used for the determination of both metallic and none-metallic impurities are described. Efficient determination of metallic impurities by GD-MS via differential and absolute measurements with a significantly reduced target uncertainty of 20 % for absolute measurements using liquid doped pressed powder calibration could be achieved. The determination of impurities has been evaluated by independent analytical methods such as HR-ICP-MS, ETAAS; CGHE and combustion analysis
A magnetically stabilized DC arc device, designed for operation with OES spectrometers was used to determine the elements Ag, Al, B, Ba, Be, Ca, Co, Cr, Cu, Fe, Ga, In, K, Li, Mg, Mn, Mo, Na, Nb, Ni, Si, Sn, Sr, Ti, V, Zr at trace levels of some μg kg−1 up to some 10 mg kg−1 in graphite powders. The coil for the generation of the homogeneous magnetic field was placed outside the closed arc chamber. The time programs of variable current strengths of the magnetic coil (up to 6 A) and of the arc (up to 17 A) which was burning in air were computer controlled. Halogenating gases (mainly CCl2F2, alternatively SF6 and NF3) were used as chemical modifiers to allow an effective release of the carbide forming trace elements. The mass flow controlled modifier gas was led through a special carrier electrode near the arc plasma. The emission radiation was guided by an optical fiber alternatively into two different ICP spectrometers in which the ICP torches were removed. The synergistic interaction of the magnetic field with the halogenating modifier gases resulted in a significant improvement in the analytical performance of the optimized analytical method. All our results for 22 trace elements were in good agreement with the means of an inter-laboratory comparison by BAM for certification of a pure graphite powder material; this holds also for our results for two other graphite materials. The optimized method showed an analytical performance suitable for comprehensive trace analysis of pure graphite. The instrumentation could be integrated into modern DC arc emission spectrometers to improve their analytical capabilities substantially.
The analytical potential of a nanosecond laser ablation inductively coupled plasma mass spectrometer (ns-LA-ICP-SFMS) system, equipped with an ultra-fast wash-out ablation chamber, is critically investigated for fast and highly spatially resolved (∼μm) qualitative elemental distribution within single cells. Initially, a low surface roughness (< 10 nm) thin In–SnO2 layer (total coating thickness ∼200 nm) deposited on glass is employed to investigate the size, morphology and overlapping of laser-induced craters obtained at different laser repetition rates, making use of Atomic Force Microscopy (AFM). Conical craters with a surface diameter of about 2 µm and depths of about 100 nm were measured after a single laser shot. Furthermore, the influence of the sampling distance (i.e. distance between the sample surface and the inner sniffer of the ablation chamber) on the LA-ICP-MS ion signal wash-out time is evaluated. A significant decrease of the transient 120Sn+ ion signal is noticed after slight variations (±200 μm) around the optimum sampling position. Ultra-fast wash-outs (< 10 ms) are achieved reducing the aerosol mixing from consecutive laser shots even when operating the laser at high repetition rates (25 – 100 Hz). Fast and highly spatially resolved images of elemental distribution within mouse embryonic fibroblast cells (NIH/3T3 fibroblast cells) and human cervical carcinoma cells (HeLa cells), incubated with gold nanoparticles (Au NPs) and Cd-based quantum dots (QDs), respectively, are determined at the optimized operating conditions. Elemental distribution of Au and Cd in single cells is achieved using a high scanning speed (50 µm/s) and high repetition rate (100 Hz). The results obtained for the distribution of fluorescent Cd-based QDs within the HeLa cells are in good agreement with those obtained by confocal microscopy. The size, morphology and overlapping of laser-induced craters in the fixed cells are also investigated using AFM, observing conical craters with a surface diameter of about 2.5 µm and depths of about 800 nm after a single laser shot.
In supplementary work to the one published earlier, experiments with SF6, NF3, CF4 and H2 as new modifier gases for the matrix studied were performed. Our investigations were continued to improve the described analytical method and to achieve additional insights into the mechanism of analyte release. Our new survey is split in two parts. At first fluorinating modifiers were used to investigate the behaviour of a variety of trace elements (Ag, Al, As, Au, Bi, Cd, Co, Cr, Fe, Mg, Mn, Ni, P, Pb, Sb, Se, Si, Sn, Te, Ti, Zn and Zr). Most of them (exceptions Au, Se, and Te) could be effectively released from the copper matrix by thermo-halogenation reactions and by partial sub-sample evaporation. Using SF6 and NF3 as modifier gases, low limits of quantification (LOQs) were achieved for the 19 well released trace elements (typical ≤0.1 mg kg-1). Most elements (exceptions Ag, Mg, and Ni) could be calibrated by using aqueous calibration solutions without any sample pretreatment. For the trace determination of Se, Te, and Au, a further analytical method of ETV-ICP OES is described in the second part based on thermo-hydrogenation reactions by using a hydrogen/argon mixture as a modifier gas. The determination of Se and Te with very high analytical performance (LOQ < 0.1 mg kg-1) can either be carried out in a second analytical step succeeding the halogenation procedure, or the sub-sample is directly treated with H2 without previous halogenation procedure whereby the sub-sample can either be partially or totally evaporated. In this case some other analytes (Ag, Au, As, Bi, Cd, Fe, Mg, Ni, Pb, Sb, Sn, and Zn) can additionally be quantified simultaneously with Se and Te.
Vortrag zur Bestimmung von Nichtmetallen in Carbiden halten.
Hierbei geht es um die Bestimmung von C, O und N in Vanadiumcarbid, Wolframcarbid und Niobcarbidmaterialien, einen hierzu durchgeführten Ringversuch mit Beteiligung der Kollegen des AK Sonderwerkstoffe und den Vergleich von Verfahrenskenngrößen.
The analytical potential of a nanosecond laser ablation coupled plasma mass spectrometer (ns-LA-ICP-SFMS)system is investigated for fast and highly spatially resolved (~µm) elemental distribution within single cells. The size, morphology and overlapping of laser-induced craters has been investigated with Atomic Force Microscopy (AFM).
The formation of diffusion layers on Zn layers deposited on Al substrates is mainly used to prevent corrosion effects. Evaluation of the influence exerted by different coating methodologies and heat treatments on the formation of these diffusion layers is of great interest for the aluminium industry. Particularly, multi-elemental in-depth distributions of major, minor and trace elements in Zn-coatings is highly demanded before and after heat treatments. A fast characterization of these materials require a direct solid analytical technique able to provide high sensitivity and high depth resolution. For this purpose, an improved analytical method based on the use of pulsed glow discharge sector field mass spectrometry (pulsed-GD-SFMS) is investigated. Glow discharge operating parameters (e.g. pulse duration, pulse frequency), glow discharge source design (e.g. flow tube lengths), and SFMS mass spectra acquisition conditions (e.g. integration time) are evaluated to achieve low sputtering rates, high mass spectra acquisition rates and improved depth resolution. At the optimize conditions Zn coatings deposited by arc-spray and electrodeposition are analysed before and after heat treatments to evaluate the diffusion of different key elements. Moreover, results are validated using femtosecond laser ablation (fs-LA)-ICP-MS, which provides additional information about the heterogeneous distribution of some elements in the Zn coatings.
Mixed copper and titanium hydride powder was hot-pressed and characterized by Carrier Gas Hot Extraction, XRay Diffraction, Thermal Gravimetric Analysis coupled with Mass Spectrometry, and Scanning Electron Microscopy.
The hot-pressed and five conventional samples were applied for calibration of hydrogen in Glow Discharge Optical Emission and Mass Spectrometry. Up to the introduction of 15 ng/s hydrogen the Emission yield model is useful in Glow Discharge Optical Emission Spectrometry. A correlation between saturation and even reversal of the emission yield of the spectral lines H121, H486 and H656 and low sputtering rates was found. Hydrogen effects exist for the spectral lines of Cu(II) 219 and Ti(I) 399. In Glow Discharge Mass Spectrometry, a linear dependency of the 1H ion current on the sputtered mass per time exists over the total range of hydrogen content investigated. Hydrogen effects also exist for the sensitivity of 48Ti and 63Cu. The sputtering rate of two-phase materials depends linearly on the sputtered mass per time of one phase, which allows the sputtering rate of two-phase materials with known composition to be predicted.
High spatially resolved quantitative bioimaging of CdSe/ZnS Quantum Dots uptake in two kinds of cells is investigated combining laser ablation inductively coupled plasma mass spectrometry and the spatially resolved analysis of dried pL-droplets from a solution with a known concentration of Quantum Dots. Single cells and dried pL-droplets are morphologically characterized by Atomic Force Microscopy. A number concentration of CdSe/ZnS QDs between 3.5 104 and 48 104 is estimated to be uptaken by several selected single cells, after being incubated in the presence of a QDs suspension added to a standard cell culture medium. Mono-elemental bioimaging at subcellular resolution seems to show a higher number concentration of the CdSe/ZnS QDs in the cytosol around the cell nucleus.
Within the Working Group on Inorganic Analysis (IAWG) of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) international key comparisons and pilot studies related to inorganic analysis are carried to ensure consistency in this field at the highest level. Some of these comparisons deal directly with the preparation and characterization of monoelemental solutions or with topics, closely related. The importance of monoelemental solutions lies in the fact that almost every measurement in inorganic analysis relies on the comparison with either a reference material, or references in form of solutions, usually (mono)elemental solutions. All quantitative measurement approaches, e.g. isotope dilution or standard addition, need an accurate reference solution made from a well characterized reference material, prepared under full gravimetric control. These primary (monoelemental) solutions do not only serve as arbitrary references/calibration solutions, but they also link up measurement results to the International System of units (SI), this way establishing the so-called metrological traceability to a measurement unit of the SI. Without such solutions on the highest possible level of accuracy and with the smallest possible associated uncertainties (for e.g. element content and/or impurities), an analysis itself can never be as good as it could be with appropriate reference solutions. This article highlights select key comparisons and pilot studies dealing with monoelemental solution related topics within the IAWG from the foundation of CCQM – 25 years ago – up to latest achievements in the field of inorganic analysis.
Die metallischen Verunreinigungen in Metallen lassen sich mittels hochauflösender Massenspektrometer relativ einfach ermitteln. Die Glimmentladungs-Massenspektrometrie (GD-MS) stellt hierfür eine schnelle Multielementmethode dar. Aufgrund ihrer höheren Anregungs- und Ionisationsenergien ist die Bestimmung von Nichtmetallen eine weit größere Herausforderung. Außerdem fehlt es an für die direkte Feststofftechnik notwendigen Kalibrierstandards z.B. in Form zertifizierter Referenzmaterialien. Für die quantitative Bestimmung von Verunreinigungen wurden mit Standards dotierte Pulverpresslinge und dotierte, gesinterte Materialien auf ihre Eignung als Kalibrierstandards für die GD-MS untersucht. Dabei kamen unterschiedliche Plasmabedingungen (gepulster/ kontinuierlicher Betrieb; verschiedene Plasmagase) zum Einsatz. Ein Überblick über analytische Kenngrößen und Grenzen der verwendeten Kalibrierstrategien wird gegeben. Zur Validierung des Verfahrens wurde die hochauflösende Continuum Source Absorptionsspektrometrie (HR-CS-MAAS) verwendet. Die analytische Nutzung der Molekül-absorptionsspektrometrie zur Bestimmung von Halogenen basiert auf der Bildung insitu-generierter zweiatomiger Moleküle (AlCl, GaF). Die entstehenden Molekülspektren werden im Echelle-Spektrometer aufgespalten und mittels CCD-Array detektiert, was eine sehr empfindliche Messung und präzise Quantifizierung ermöglicht.
Normally, in analytical GD-MS, the doubly charged metallic ion signals from the sample are several orders of magnitude less than the corresponding singly charged signals. However, we have observed that using a neon plasma, the M++ signals of some elements, which have double ionization energies close to the first ionization energy of neon, are of the same order as the M+ signal. Doubly charged ions may be produced directly in the discharge cell by electron ionization (EI), and also by two electron Penning ionization (TEP), but these processes cannot explain the above effect. In this paper, we suggest that an additional process named as ‘Charge Transfer and Ionization’ (CTI) produces such ions either in their ionic ground state or in an excited state. To confirm that this process is typical of the discharges used in GD-MS and not an artefact of any particular form of cell and ion extraction system, we have carried out comprehensive experimental measurements using three different GD-MS instruments, viz., Nu Astrum, VG9000 and ELEMENT GD and our results provide clear evidence for CTI. This is the first time the process has been identified as an ionization process in analytical GD-MS. CTI must be differentiated from Asymmetric Charge Transfer (ACT), which is a “selective” process and requires a close energy match (e.g. ΔE < 0.5 eV for a strong effect). On the other hand, CTI is “non-selective” in the sense that a close energy match is not required (e.g. a strong effect is observed with ΔE ∼ 2 eV), although the process only occurs for a limited number of elements, depending on the plasma gas used and the total energy required to doubly ionize the metallic atom.
Die Einwerbung von Drittmitteln wird immer mehr zur zwingenden Notwendigkeit, wenn man Forschung betreiben möchte. Drittmittel sorgen nicht dafür, dass man zusätzliches Geld für die Forschung ausgeben kann, wie das früher einmal der Fall war, sie werden mehr und mehr zur Grundbedingung für Forschung überhaupt. Zu den Drittmitteln zählen insbesondere Projektmittel der Forschungsförderung des Bundes, der Länder, der EU und anderer öffentlicher Stellen, der Wirtschaft zur Durchführung von Forschungsaufträgen sowie der Deutschen Forschungsgemeinschaft. Sie machen bereits einen entscheidenden Teil des Budgets von Universitäten (25-30%, Tendenz steigend) und Forschungseinrichtungen aus. In den Präsidien und Rektoraten werden Stabsstellen eingerichtet, um mögliche Fördertöpfe zu finden und erfolgreiches Formulieren von Anträgen zu unterstützen und die Formalien der Antragstellung zu optimieren. Je mehr Drittmittel eine Einheit einwirbt, mit umso mehr Grundmitteln darf sie rechnen. Dem hohen Zeitaufwand der Wissenschaftler für das Schreiben von Anträgen stehen jedoch immer niedrigere Bewilligungsquoten gegenüber. Sehr umfangreiche Projekte mit sehr vielen Partnern scheinen immer schwieriger zu begründen zu sein. Lange Bearbeitungszeiten bis zur Bewilligung von Projekten und Laufzeiten von 4 Jahren stehen im Widerspruch zu den Planungszeiträumen für Forschungsprojekte im Industrielabor. Im Zeichen immer stärker geforderter Interdisziplinarität müssen andere Wege gefunden werden, um die Stärken einer Messtechnik überzeugend einzubringen.
Was ist zu tun? In diesem Diskussionsbeitrag werden Informationen zusammengetragen, um Fördermöglichkeiten der Grundlagenforschung und Applikationen von GD-techniken auszuloten und die Kooperation von Forschungseinrichtungen und Industriepartnern praktikabel zu realisieren.
Analytical glow discharges with optical (GD-OES) and mass spectrometric (GD-MS) detection are able to obtain depth resolved information about the light elements hydrogen, carbon, nitrogen and oxygen in solid samples, where most of the other analytical techniques fail. However, the interpretation or even quantification of the measured signals is still very challenging. Problems arise due to physical effects (plasma processes such as the ‘Hydrogen effect’, the Doppler effect, self absorption or diffusion of hydrogen in the sample during sputtering) chemical effects(e.g. formation of compounds with argon or the matrix, poisoning of the sample or gettering) as well as instrumental difficulties (e.g. of the sensitivity, calibration and vacuum quality)..
The GD techniques are direct solid sampling methods and require reference materials for calibration. Unfortunately the list of available certified reference materials (CRM) suited for calibration of light elements in different matrix is relatively short Therefore, sintered materials doped with the analytes H2, O2 and N2 were produced at IFW Dresden and applied as calibration standards for hydrogen, oxygen and nitrogen. Due to the high analyte concentration added, it is very likely that the real concentration agree well with the added amount of light elements in the corresponding phases. The validation of the determination of the light element concentration in the sintered samples was possible in some cases only due to the lack of suitable techniques. This fact proves the need for the development of a reliable quantification of light elements by GDS.
A systematic dependence of the sputtering rate on the composition was found and can be explained by basic principles.
Using mixtures of TiH2 and ZrH2 with Cu the ratio of hydrogen and Cu lines has a good correlation with the corresponding concentration ratio. The hydrogen emission yield however decreases over 0.3 m% hydrogen and finally the hydrogen intensity may even decrease. This behaviour can be explained by a very similar quenching of the hydrogen and copper intensity caused by the hydrogen effect. First experiments with GD-MS show no saturation of the hydrogen ion current and thus confirm the quenching of the emission yield in GD-OES.
Sintered material for the oxygen calibration (Al2O3, CuO, Cu2O and MgO mixed with Cu, Al and Mg) confirmed the blue line shift effect at O I 130.22 nm, first time reported by Köster 2009 [1]. The effect is more pronounced at Mg than in Al and Cu, which due to line interference leads to a matrix dependent EY. This effect is negligible at O I 777.19 nm and the EY is matrix independent. Using GD-MS first promising results for the calibration of oxygen with these sintered samples could be obtained, when the sputtering rate was included in the evaluation.
More recently also sintered material for nitrogen calibration (AlN mixed with Al and Si3N4 mixed with Cu) was produced and points to a matrix independent emission yield of nitrogen
Die Junganalytiker der Fachgruppe „Analytische Chemie“ der Gesellschaft Deutscher Chemiker (GDCh) veranstalteten in Zusammenarbeit mit der BAM eine Herbstschule zum Thema „Qualitätssicherung in der Analytischen Chemie“.
Schulung v.a. für Doktoranden, um den Umgang mit qualitätssichernden Aspekte bei der Entwicklung analytischer Methoden zu erlernen.
Die wichtigsten Grundbegriffe der Genauigkeitskenngrößen von Messgrößen werden in diesem Vortrag vermittelt.
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).