Dissipation and dynamics of mesotrione in maize and soil under field ecosystem.

Modified QuEChERS-HLPC (quick, easy, cheap, effective, rugged and safe) methods for the analysis of mesotrione in maize and soil were developed and validated. At three fortification levels of 0.01, 0.1 and 0.5 mg kg(-1) mesotrione, the recoveries of mesotrione in maize plants, maize and soil were in the range of 85.95 %-96.05 %, with relative standard deviations (RSD) of 2.89 %-9.83 %. The limit of quantification (LOQ) of method was 0.001 mg kg(-1) for maize and soil. In the supervised field trials, the degradation rates of mesotrione were described using first-order kinetics and mesotrione dissipation in maize plants coincided with C ( t ) = 1.735e(-1.0194t) with the half-life 3.94 days in Tianjin, and C ( t ) = 4.9536e(-0.7237t) with the half-life 5.10 days in Jilin. As for soil, C ( t ) = 20.272e(-1.208t) with the half-life 2.98 days in Tianjin, and C ( t ) = 5.5835e(-8141t) with the half-life 4.49 days in Jilin. At pre-harvest interval (PHI) of 0 and 20 days, the final residue levels of mesotrione could not be detected in maize and soil at the recommended dosage and 1.5 times recommended dosage.