Determination of pymetrozine residues in cucumber

An experiment was carried out to investigate the residues of pymetrozin in cucumber under field conditions. Plots of cucumber (cv. Daminus) were sprayed with pymetrozine (Chess, WG50) at two different rates; 0.5 and 1.0 kg/ha. Samples were collected 2 hours and 1, 2, 3, and 4 days after spraying and pymetrozin residues were determined using high performance liquid chromatography with UV detector. Two hours after spraying, the residues was 0.326 mg/kg for 0.5 kg/ha treatment. The residues decreased to 0.013 mg/kg on the third day and no residue was detected four days after spraying. In 1.0 kg/ha treatment, the residue was 0.627 mg/kg, two hours after spraying, which decreased to 0.028 mg/kg, on the third day, but no residues was found in samples which collected four days after spraying. In farm plots which received 0.5 kg/ha pymetrozine, the residues in peels and peeled cucumber were 0.359 and 0.308 mg/kg respectively, two hours after spraying, but in plots which sprayed at 1.0 kg/ha, the residues were 0.648 and 0.609 mg/kg respectively. Furthermore the residues in peels showed a significant difference with those of peeled and unpeeled cucumber under field conditions.