knowledge. This material provided has been collected from different sources. One important source is the material available from EURACHEM. Eurachem is a network of organisations in Europe having the objective of establishing a system for the international tra- ability of chemical measurements and the promotion of good quality practices. It provides a forum for the discussion of common problems and for developing an informed and considered approach to both technical and policy issues. It provides a focus for analytical chemistry and quality related issues in Europe. You can find more...