4. Conclusion

In order to be able to compare measurement results, metrological traceability must be guaranteed. Five steps are necessary to ensure this: definition of the measurand, identification of factors with a significant influence on the measurand value, modeling of the measurement, choice and application of references for each previously identified influencing factor, assessment of the uncertainty of measurement. In chemistry, this metrological traceability faces two major problems: on the one hand, the multiplicity of measured parameters makes it impossible to have as many recognized references, and on the other, the lack of knowledge of some of the phenomena involved. To remedy these difficulties, which can lead to breaks in the traceability chain, laboratories have developed tools such as certified reference materials, and have used the concept of measurand, the definition of which includes...