Requirements for the Preparation of Reference Materials

A series of requirements have to be respected for the preparation of RMs and CRMs. They include three basic properties (i) the representativeness of the sample (ii) the homogeneity and (iii) the long term stability. The following sections give the general rules to be followed for the preparation of matrix RMs. The procedure has to be adapted to the type of material to be prepared and to the objective it has to fulfil. 

In order to arrive at sound conclusions on the analytical performance of a method or of a laboratory, the RM should be similar to samples currently analysed by the laboratory in its daily practice. This means that the RM 

The requirement of representativeness of the RM means in most cases similarity of  

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