Dissipation of propisochlor and residue analysis in rice,soil and water under field conditions

The analytical method for the residues of a new herbicide propisochlor and its dissipation and residual amounts in soil, water and rice plants in field conditions (rice cropping system) were studied. The chloroacetanilide herbicide, propisochlor (72% w/w EC) was applied at two dosages, 108 g a.i. ha⁻¹ (recommended) and 162 g a.i. ha⁻¹ (1.5 times of the recommended dosage) seven days after transplanting rice seedlings in the experimental fields in both Beijing and Fujian provinces (experimental localities). Soil, water and rice plant samples were collected at intervals and analyzed for propisochlor residues. The detection limit (LOD) of propisochlor is 0.2 μg kg⁻¹ and the limit of quantification (LOQ) was established as 1 μg kg⁻¹. At three different spiking levels, mean recoveries and relative standard deviation (RSD) from fortified samples in three replicated experiments for each matrix were in the range 81–109% and 1.3–13.1%, respectively. The results showed that the half-lives of propisochlor in water, soil and rice plant from Beijing were 0.56, 5.25 and 1.46 days respectively, and the half-lives of propisochlor in water, soil and rice plant from Fujian were 0.62, 5.12 and 0.81 days. At harvest, soil, straw, rice hull and husked rice samples were found to contain propisochlor well below the limit of detection (LOD) following the recommended dosage and 1.5 times dosage.