Sizing based on sieving and centrifuging

3 Fractionation of species based on selective sizing 2.3.1 Sizing based on sieving and centrifuging 

Species distribution studies have shown that trace element (e.g. metals) concentrations in soils and sediments vary with physical location (e.g. depth below bed surface) and with particle size. In these speciation studies the total element content of each fraction was determined using a suitable trace element procedure, for example, solid sample analysis by X-ray emission spectroscopy or neutron activation analysis, or alternatively by dissolution of sample and analysis by ICPOES, AAS or ASV. The type of sample fraction analysed can vary, and a few 

Sub-division of particulate matter (e.g. separation of denser particles from colloids) can be achieved by centrifuging but the efficiency of the process depends on the size and density of the particles, and the speed and duration of the centrifugation. 

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