2. Definition of analyzed media

Samples to be analyzed in the environmental and health fields may be in liquid or solid form. Liquids are either aqueous (water, beverages, urine, blood, milk, etc.) or in some other form (oils, etc.). Solid samples may contain a majority of organic matter (plant and animal tissues) or inorganic matter (soils, sediments...). Each of these cases requires a different analytical approach, selected on the basis of the sample's composition in terms of both majority and minority constituents, especially if it is the latter that are the subject of the analysis.

To simplify the problem, we can consider that the organic part of the sample is decomposed and eliminated during the preparation stages. The residue analyzed therefore contains only mineral compounds in highly variable concentrations. These include major elements (the matrix) present at concentrations of over 0.1%...