Basic Training 4th Annual ICP Conference

3:11 Sampling and sub-sampling

Contamination Issues During Sampling

Geological: Sampling of geological materials can require hundreds of kilograms of material to be processed for the determination of certain elements present in inclusions. For example, Mo and Nb in granite.

Figure 3.1: Generation of Geological Sample Geological outcrop sampling

crush and mill to sand size

split to 1/8 the volume

grind to coarse powder

split to 1/8 the volume

grind to fine powder (60 microns )

When using tungsten carbide crushing and grinding apparati, the common contaminants are W, Cr, Mn, V ,Co, Fe, Cu, Zr and Zn. Sieves made of nylon are recommended to avoid contamination by all metals.

3:12 Sampling and sub-sampling

Contamina(on Issues During Sampling (cont.)

Soils: Soil is heterogeneous and the composi(on varies with depth. Essen(al and hazardous element distribu(ons down to 50 cm are of interest.

Figure 3.2: Genera(on of Soil Laboratory Sample Fresh soil ➡ vegeta(on and debris is removed and discarded ➡ clean glass jars or plas(c bags ➡ stored at 4̍C ➡ air-dried in clean place ➡ ground to break down soil aggregates ➡ piled and quartered ➡ ground to fine powder ➡ sieved (60 micron).

Grinding in Alundum ball mills is recommended to avoid contamina(on from most metals (Al, Si, and Fe are common contaminants from the Alundum). Sieves made of nylon are recommended to avoid contamina(on by all metals.