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- Copper (3)
- Calibration (2)
- Chemical analysis (2)
- Traceability (2)
- Zinc (2)
- Arrhenius model (1)
- Boron (1)
- Certified reference materials (1)
- Complexing agents (1)
- ERM (1)
- Element determination (1)
- Emission spectroscopy (1)
- Fixed-points (1)
- GD-MS (1)
- GD-OES (1)
- Glow discharge (1)
- Grimm type glow discharge (1)
- High resolution glow discharge mass (1)
- Hollow cathode (1)
- Homogenität (1)
- ICP-MS (1)
- ITS-90 (1)
- Impurities (1)
- Kupfer (1)
- LA-ICP-MS (1)
- LA-ICP-OES (1)
- Laser ablation (1)
- Laserablation (1)
- Magnesium (1)
- Matrix evaporation (1)
- Matrix separation (1)
- Metal (1)
- Metrology (1)
- Metrology in chemistry (1)
- Micro-hardness (1)
- Pin sample (1)
- Primary standards (1)
- Purification (1)
- Sample enrichment (1)
- Sector field mass spectrometry (1)
- Sensitivity (1)
- Shelf life (1)
- Solar grade silicon (1)
- Spark-OES (1)
- Spectrometry (1)
- Stability (1)
- Ultra high purity (1)
- Uncertainty (1)
- Vacuum distillation (1)
- ZRM (1)
Calibration of two commercially available glow discharge double focusing mass spectrometers, the VG 9000 and Element GD, is described using synthetic pin standards pressed from solution doped copper and zinc matrices. A special pressing die was developed for this purpose and optimal results were obtained with the highest possible pressures, i.e., 95 kN·cm- 2. This calibration approach permits the determination of trace element mass fractions down to µg·kg- 1 with small uncertainties and additionally provides traceability of the GD-MS results in the most direct manner to the SI (International System of Units). Results were validated by concurrent measurements of a number of compact copper and zinc certified reference materials. The impact of the sample pin cross-section (circular or square) was investigated with the use of a new pin-sample holder system for the Element GD. The pin-sample holder was designed by the manufacturer for pin-samples having circular cross-section; however, samples with square pin cross-section were also shown to provide acceptable results. Relative Sensitivity Factors for some 50 analytes in copper (VG 9000, Element GD) and zinc matrices (VG 9000) are presented. The field of applicability of GD-MS may be considerably extended via analysis of pin geometry samples based on their ease of preparation, especially with respect to the accuracy and traceability of the results and the enhanced number of analytes which can be reliably calibrated using such samples.
Determining the influence of impurities on the fixed-point emperatures
of the ITS-90 requires the completion of several tasks. In this paper, the Progress made at Physikalisch-Technische Bundesanstalt (PTB) and BAMFederal Institute for Materials Research and Testing is presented and remaining questions are discussed.
The projected characterization procedure at PTB, which is based on the established SIE method (sum of the individual estimates), using a new indium fixed-point cell is described as an example. This procedure includes an SI-traceable chemical Analysis of the material in the fixed-point cell with sufficiently low uncertainties, the individual experimental determination of the influence of the quantified impurities on the fixed-point temperature, and the establishment of direct links to the phase-transition temperatures of the national standard and of an assumed material of ideal purity.
A characteristic difference to the common practice is the chemical analysis of the fixed-point metal being done after determining the cells freezing temperature. This allows for the detection and consideration of contamination and purification effects due to the filling process, or due to the contact with the carbon crucible and other parts of the fixed-point cell. A chemical analysis of an indium fixed-point was carried out by BAM with relative measurement uncertainties below 30 % which have not been previously achieved. The results provide evidence for the precipitation of some impurities,
which is apparently inconsistent with the corresponding binary phase diagrams, but was explained in a recent publication. Implications for the use of the SIE method shall be described briefly at the end.
Methods for the determination of boron in various matrices described in the literature usually employ complexing agents like mannitol to retain the volatile boron species during matrix evaporation steps. However, also relatively high boron recoveries from silicon containing samples have been reported when no complexing agents were added to the digestion acids. The mechanism behind this matrix-dependant recovery has been investigated by studying the boron recovery in the analysis of solar grade silicon. It was found that the NH4+ ion formed by the reduction of nitric acid during sample digestion is responsible for the higher recovery of boron, which leads to a possible analysis method without the use of complexing agents if the sample preparation procedure is carefully optimized.
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.
Detection and monitoring of volatile elements released during the preparation of ultra high purity zinc by vacuum distillation (VD) is reported using online quadrupole gas source mass spectrometry (QMS). The theoretically calculated vapour pressures (pv) for the volatile impurity elements using Dushman constants and the practically observed mass spectra were found to be consistent (S. Dushman and J. M. Lafferty, Scienific Foundations of Vacuum Technique, 2nd ed., Wiley, New York, 1962). This is the first time that the potential ability of an online mass spectrometer was used for monitoring and understanding the process mechanism during the purification of metals (Zn) using VD. We here also illustrate our findings with the results from high resolution glow discharge mass spectrometer (HR-GDMS) analysis before and after the purification of Zn.
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.
In Germany a system of primary amount of substance standards for elemental analysis is being developed, which forms the material´s basis for the National Standards for element determination. The metrological concept and technical approach is briefly described. The objective of traceability in chemistry, in this case for elemental determination, is illustrated on the example of copper.
In this work, we report on the application of hyphenated gas source mass spectrometry to study and understand the mechanism of the reduction-distillation of ZnO using Al powder as reductant in its activated and inactivated form. The experiments revealed that the purity of the Zn metal produced were superior using activated Al with respect to inactivated Al, i.e., m5N8 (99.9998% metallic based) versus m5N3. The achieved purity levels of Zn and the absence of high volatile Cd, Mg, and Sb impurities in the gas phase and the material collected were explained with respect to the impurity elements free-energy values, vapor pressure data, and an observed scavenging effect of the Ta crucible, which was supported by the on-line observed mass spectrometric profiles of the residual gas.