Filtern
Erscheinungsjahr
- 2011 (5) (entfernen)
Dokumenttyp
Schlagworte
- Emission (2)
- Quecksilber (2)
- Zinn-Amalgamspiegel (2)
- AOX (1)
- Boden (1)
- Comparability (1)
- Eignungsprüfung (1)
- Electrotechnical products (1)
- Elemental analysis (1)
- Elemental composition (1)
Within the scope of a project of the 'European Association of National Metrology Institutes' (EURAMET), a European metrological dissemination System (network) providing traceable reference values assigned to matrix materials for validation purposes is described and put to the test. It enables testing laboratories (TL) to obtain comparable results for measurements under the 'EU Water Framework Directive 2000/60/EC' (WFD) and thus, to comply with a core requirement of this very directive. The dissemination system is characterized by the fact that it is available to all laboratories throughout Europe which intend to perform measurements in the context of the WFD and that it can ensure sustainable metrological traceability to the International System of Units (SI) as a reference point for the measurement results. This Dissemination system is set up in a hierarchical manner and links up the level of the national metrology institutes (NMI) with that of the TLs via an intermediate level of calibration laboratories (CL) by comparison measurements. The CLs are expert laboratories with respect to the measurement of the analytes considered here (within the project, the CLs are called potential calibration laboratories (PCL)) and are additionally involved in the organization of comparison measurements within the scope of regional quality assurance (QA) systems.
Three comparison measurements have been performed to support the approach. A total of about 130 laboratories participated in this exercise with the focus on the measurement of the priority substances Pb, Cd, Hg, and Ni defined in the WFD. The elemental concentrations in the water samples roughly corresponded to one of the established environmental quality standards (EQS), the annual average concentration (AA-EQS), which is defined in the daughter Directive 2008/105/EC of the WFD. It turned out that a significant number of TLs still need to improve their measurement methods in order to be able to fulfill the Minimum requirements of the WFD, in particular, with regard to the elements Cd and Hg probably due to their low EQS values.
Furthermore, it became obvious that the hierarchical Dissemination system suggested here actually corresponds to the measuring capabilities of the three participating Groups (NMIs, PCLs, and TLs).
With the implementation of glass casting in France in the second half of the 17th century, larger mirrors could be produced. So-called tin-mercury mirrors were made by coating glass with tin amalgam. Today, many historical mirrors are partly damaged, the image quality is compromised, and the material integrity of the mirror is threatened. The transformation from tin into an oxide starts at the surface of the amalgam and proceeds down to the glass surface. The mercury dissolves as a liquid or gaseous phase. The amalgam layer is destroyed, so that conservation is necessary. Conservators must follow strict safety precautions while handling amalgam mirrors because of possible mercury emissions and corrosion of the amalgam, during which elemental mercury accumulates near the mirror frame in droplets and is emitted into the air.
In a research project, the quantity of the mercury emissions from historical mirrors was examined and a technique to decrease these emissions was developed.
With the implementation of glass casting in France in the second half of the 17th century, larger mirrors could be produced. So-called tin-mercury mirrors were made by coating glass with tin amalgam. Today, many historical mirrors are partly damaged, the image quality is compromised, and the material integrity of the mirror is threatened. The transformation from tin into an oxide starts at the surface of the amalgam and proceeds down to the glass surface. The mercury dissolves as a liquid or gaseous phase. The amalgam layer is destroyed, so that conservation is necessary. Conservators must follow strict safety precautions while handling amalgam mirrors because of possible mercury emissions and corrosion of the amalgam, during which elemental mercury accumulates near the mirror frame in droplets and is emitted into the air.
In a research project, the quantity of the mercury emissions from historical mirrors was examined and a technique to decrease these emissions was developed.
The EU RoHS Directive (2002/95/EC of the European Parliament and of the Council) bans the placing of new electrical and electronic equipment containing more than agreed levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants on the EU market. It necessitates methods for the evaluation of RoHS compliance of assembled electronic equipment. In this study mounted printed circuit boards from personal computers were analyzed on their content of the three elements Cd, Pb and Hg which were limited by the EU RoHS directive. Main focus of the investigations was the influence of sample pre-treatment on the precision and reproducibility of the results. The sample preparation steps used were based on the guidelines given in EN 62321. Five different types of dissolution procedures were tested on different subsequent steps of sample treatment like cutting and milling. Elemental analysis was carried out using ICP–OES, XRF and CV–AFS (Hg). The results obtained showed that for decision-making with respect to RoHS compliance a size reduction of the material to be analyzed to particles ≤1.5 mm can already be sufficient. However, to ensure analytical results with relative standard deviations of less than 20%, as recommended by the EN 62321, a much larger effort for sample processing towards smaller particle sizes might be required which strongly depends on the mass fraction of the element under investigation.