Degradation profile and safety evaluation of methomyl residues in tomato and soil

A high performance liquid chromatography with the photodiode array detector (HPLCDAD) analytical method was developed to determine the residue levels and investigate the dissipation pattern and safety use of methomyl in tomato and soil. Methomyl residues were extracted from tomato and soil samples with ethyl acetate. The extract was cleaned up with the QuEChERS method. The results showed that the average recoveries were in the range of 87.1-94.5%, with RSD of 6.9-11.2%. Limits of detection (LOD) and quantification (LOQ) were 0.005 and 0.007 mg/kg, respectively. The residue levels of methomyl were best described to first order rate kinetics and half-lives ranged from 1.34 to 1.8 days in tomato and soil, respectively. The theoretical maximum residue contributions for methomyl on tomato were found to be less than the maximum permissible intake values even on zero days, therefore consumer health risks are minimal at the recommended dose on tomato.