More polar herbicides and pesticides

Herbicides are components with relatively low Kow values and high solubilities. This means that they can be extracted from soil with a water/acetone mixture. To enable the measurement of low concentrations, the herbicides have to be transferred to a volatile solvent, which is not miscible with water, like petroleum ether or dichloromethane. If the original acetone/water extraction medium is concentrated (evaporation), the water percentage will increase during the concentration and the extracted components will precipitate or adsorb to the equipment. It is therefore necessary to add a solvent like petroleum ether to the system. There will be a distribution between the soil and the acetone/water mixture and one between the acetone/water mixture and the petroleum ether. If the water content is low the system is very effective for non-polar components. With a higher water content it will be more effective for more polar components. With a too high water content the accessibility increasing properties of acetone are lost and the efficiency of the extraction process decreases. 

After the removal of the soil the acetone can be removed by extraction with water. Non-polar components will stay in the petroleum ether phase. More polar components like the herbicides may be removed together with the acetone from the petroleum ether. 

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