4. Solution treatment of solid samples

Solid samples collected during a sampling campaign are generally not sufficiently homogeneous for analysis purposes. This requires preliminary treatment to obtain a more representative sub-sample with a finer particle size. For dry solid samples of a certain hardness (soils, sediments...), these treatments consist in grinding (dry or liquid), either manually (mortar) or mechanically (ball mills, rings, discs, hammers...), using various materials of suitable hardness (steel, agate, boron or tungsten carbides, corundum...). The homogenization of less resistant solid samples (plant and animal tissues, foodstuffs, etc.) is usually carried out using a variety of mixers. Some fresh organic samples can be made more crumbly by freezing in liquid nitrogen, making them easier to grind.

Samples may be pre-dried at room temperature in air (especially for mercury determination)...