Assessing the Dissipation of Pesticides of Different Polarities in Soil Samples

Abstract

A methodology has been developed to assess the presence and dissipation of herbicides of wide range of polarities in soil using in-tube solid phase microextraction (IT-SPME) coupled on-line to capillary liquid chromatography (capLC). The compounds investigated were tritosulfuron (TRT), triflusulfuron-methyl (TRF), aclonifen (ACL) and bifenox (BF), with log octanol-water partition coefficients (log Kow) ranging from 0.62 to 4.48. The linearity, recoveries, intra and interday precision, limits of detection (LODs) and quantification (LOQs), and accuracy of the method were established. The proposed approach was successfully applied assess the degradation of the tested herbicides in different types of soil (agricultural, urban and forest) after being exposed to different laboratory and outdoor conditions. The results obtained showed a greater persistence of the most apolar compounds ACL and BF, regardless of the soil characteristics, whereas a significant degradation of highly polar herbicides TRT and TRF was observed in soils with lowest organic matter even after a few days of exposure. Those results indicate that the proposed approach can be considered an effective tool for a better understanding of soil pollution.