Effects of organic matter and clay content in soil on pesticide adsorption processes

The effect of organic matter and clay content on the adsorption of atrazine, acetochlor, clomazone, pendimethalin and oxyfluorfen in soil samples was studied. In order to determine whether and to what degree different soil properties affect the process of determination of selected pesticides, three soils with different clay and organic matter contents were used. An optimized liquid-solid extraction procedure followed by SPME measurement was applied to analyze the selected pesticides in soil samples. Detection and quantification were done by gas chromatography-mass spectrometry (GC/MS). Relative standard deviation (RSD) values for multiple analyses of soil samples fortified at 30 ?g/kg of each pesticide were below 19%. Limits of detection (LODs) for all compounds studied were less than 2 ?g/kg. The results indicate that soils with different physic-chemical properties have different effects on the adsorption of most pesticides, especially at higher concentration levels.