WP 1: Methods for impurity analysis

The aim of the work package is to develop methods for metallic and non–metallic impurity analysis of high purity materials and to demonstrate their applicability on selected guide elements that are representatives for a group of elements with similar behaviour. A consequence (or by-product) of the general method development is the availability of well characterised materials for specific elements.
Al and Mg are of great importance for industry for light weight construction material as used in car and plane construction. Zn is an element with an interesting prospect for energy production via reduction of water or use of ZnBr2. Additionally Mg and Al are relevant in clinical chemistry, especially with respect to Alzheimer disease.
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 %.
The general challenge in this type of impurity analysis lies in comprehensiveness and complexity which urgently asks for efficient methods. Moreover, addressing of homogeneity for high purity materials is difficult to achieve and even at the state of the art often simply ignored. Established but cumbersome reference methods for metallic impurities need to be applied as reference.
Special attention needs to be put on non-metallic impurities. Although they often dominate the impurity statement for a high purity material, it is a sad matter of fact that they are usually ignored, because they are difficult to measure. The choice of methods providing SI traceable results for H, N and especially O independent of matrix reference materials is limited to varieties of hot extraction. For hot extraction and combustion analysis (for C and S) a versatile calibration basis with small uncertainty and SI traceability is missing. For elements forming on the one side stable oxides and having on the other side high vapour pressures, extraction efficiency for oxygen is a crucial point.
For these activities also candidate materials must be obtained and checked for general suitability. Methodology developed must be applied to them and the results on the individual materials must be compiled for further dissemination.