4. Sample preparation

In routine situations, samples are prepared prior to storage (drying, calcination, acidification, etc.) in order to halt the biological and chemical evolution of the sample (soil, plant, water, milk, etc.), and to ensure that preservation conditions are adapted to the requirements of measurement techniques. In the emergency phase, in the case of highly contaminated samples, this stage may entail a high risk of contamination of the equipment used (grinder, oven, freeze-dryer, etc.). Depending on the urgency of the analysis and the level of activity, the possibility of analyzing the sample fresh, without any prior treatment, should be considered.