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- 2010 (6) (entfernen)
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- Zinc (2)
- Aluminium alloy (1)
- CCQM-K42 (1)
- CCQM-P107 (1)
- High purity metals (1)
- High resolution glow discharge mass (1)
- Interlaboratory comparison (1)
- International comparison (1)
- Key comparison (1)
- Micro-hardness (1)
Ultra high purity Zn (m6N5) was obtained through triple vacuum distillation using an m4N5 Zn as input material. High-volatile impurities were removed from the zinc matrix by vacuum evaporation, while traces having lower volatility than the matrix remained in the residual material after finishing of the entire purification process. The time required for the removal of the main high-volatile impurity (Cd) was monitored using a connected gas source mass spectrometer. During distillation the Zn vapor of the distillate was condensed on the cap of a glassy carbon crucible which was water cooled by a movable copper block. The temperatures were optimized for the removal of the volatiles and for the distillation process using vapor pressure data. High resolution glow discharge mass spectrometry was applied for the analysis and purity evaluation of the distilled and input zinc. The analysis confirmed the reduction of the metallic impurities from 43 mg kg-1 to 0.5 mg kg-1 (m6N5) after three consecutive vacuum distillations. An increase in the grain size and a decrease in the micro-hardness were observed for the purified Zn material.
Synthetic pressed metal powder standards doped with standard solutions were used for the calibration of both commercially available high resolution GD-MS instruments Element GD and VG 9000 for zinc matrix. Different quantification procedures (IBR, Standard RSF, matrix matched RSF from the calibration with CRMs and use of doped synthetic standards) are compared using zinc matrix as an example, whereas the calibration with doped pellets turned out to be the best quantification technique for high-purity materials. The applicability of the Standard RSF concept is scrutinised. In this context, RSF values for several Matrices (Co, Cu, Fe, In and Zn) are reported additionally.
Mass spectrometric detection can play a prominent role in the assessment of different reactions occurring at varied temperatures in a milled ZnO/Al mixture. This is the first time that online mass spectrometric information was used as a tool for monitoring and understanding the chemical reduction process mechanism. We have observed four different types of reaction taking place: (1) distillation of Zn metal, (2) reduction of ZnO by activated Al, (3) melting of Al and finally (4) reduction of ZnO by inactivated Al. The experimental conditions and results observed by QMS were supported with literature data and physical measurement data from X-Ray Diffraction (XRD) which gave us an idea about the complex reaction cascade which occurred during the formation of the zinc metal.
The degree of equivalence within the participating national metrology institutes for the measurement results of the mass fractions of the analytes Cr, Cu, Fe, Mn and Zn in an aluminium alloy was assessed. This interlaboratory comité consultatif pour la quantité de matière key comparison (CCQM-K42) was organised as an activity of the Inorganic Analytical Working Group of CCQM. In total seven laboratories participated, six of them for all analytes. Measurands were the mass fractions of the analytes in a range of 0.05 and 0.2%. As an outcome the consistency of the results for all elements investigated was acceptable, hence satisfactory comparability was established. An aluminium based certified reference material—undisclosed to the analysts which one it was—was used as test sample. For the purpose of this study homogeneity was tested at BAM. Each laboratory was free to choose any analytical method they wanted to use for the analysis. Consequently various methods of measurement were employed: instrumental neutron activation analysis, X-ray fluorescence spectrometry (XRF) using fused cast-bead method combined with reconstitution technique, inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry. Metrological traceability of the measurement results to the SI unit had to be demonstrated. Therefore, methods such as spark OES or XRF (without fused cast-bead technique)—both of them being most important methods for the analysis of metals and alloys in industrial laboratories—could not be used in the frame of the key comparison.
Within the National Metrology Institutes (NMIs) and designated laboratories, an interlaboratory comparison, CCQM-P107, was conducted to verify the degree of international comparability concerning the results of purity analysis. The mass fractions of Ag, Bi, Cd, Cr, Ni, Tl at the lower mg/kg-level in a high purity zinc material were determined, but the real measurand in metrological sense was the sum of the six mass fractions. Homogeneity was investigated by glow discharge mass spectrometry, reference values were obtained using isotope dilution mass spectrometry. Six NMIs participated, contributing eight independent data sets. The agreement amongst the results of the participants, their median and the agreement with the reference values were usually excellent and in almost all cases below the target uncertainty of 30% relative. In this manner, the accuracy of results and the comparability between the participants was demonstrated to be established.
In this work, different calibration strategies for the determination of trace elements in pure copper metal by nanosecond laser ablation ICP-MS were investigated. In addition to certified reference materials (CRMs), pellets of doped copper powder were used for calibration. The micro homogeneity of the CRMs as well as the solution-doped pellets was sufficient to use them as calibration samples in combination with a laser spot size of 200 µm. In contrast, pellets doped with analytes in solid form showed a significant heterogeneity. For most of the investigated analytes and copper CRMs the measured mass fractions were within ± 20% of their certified values when other copper CRMs were used as calibration samples. When solution-doped powder pellets were used as calibration samples a systematic trend towards mass fractions below the certified values was observed for nearly all elements determined in the analysed CRMs. Thermal fractionation effects during the ablation of the solution-doped pellets were suspected as the extent of the fractionation depends on the irradiance, whereas fractionation is reduced at higher irradiance.