Reference Methods in Ultra-trace Analysis of Milk Products

Based on experiences with international standardization of analytical methods for milk products are described the problems and solutions of collaboratively developing and testing reference and other standard methods for trace analysis of milk products. Contaminations from laboratory equipment, chemicals and air must be eliminated and interferences corrected. Precautions traditionally applied but normally unmentioned are to be identified and described. To ensure wide application of the methods the use of dangerous chemicals are avoided as far as possible and demands for expensive equipment is modest. Collaborative studies are essential before methods are finally accepted, and the results important for the status of the methods. Reference materials are useful complements to reference methods.