Imidaclopride residue levels in greenhouse-grown strawberry under cold-storage conditions

Imidacloprid is an insecticide commonly to control the sucking pests in greenhouses. Therefore the knowledge about its residue is necessary. In this research the effect of storage time on dissipation rate of imidacloprid residues in strawberry was studied. Imidacloprid (SC 35) was applied to strawberry plants at the rate of 1ml/l. The sample preparing was performed using the QuEchERS method including the extraction with acetonitrile and purification by Dispersive solid phase Extraction clean-up. Analysis of the residues was performed using HPLC method equipped with a UV detector. The Instrumental Detection Limit (IDL) was 0. 12 μgml−1. The average recovery was 94. 80%. The data were fitted to the first-order and bi-exponential kinetic models. According to the results first-order kinetics model was the best model to describe the dissipation rate of imidacloprid residues in strawberry. Half-life for degradation of imidacloprid in strawberry at 4-5 ° C was observed to be 10. 48 day using the first-order kinetics model. The residue at the application day of the insecticide was 5. 31 mg/kg، 10. 62 fold higher than the maximum residue limit (MRL) for imidacloprid in strawberries (0. 5 mg/kg) given by the Codex Alimentarius food. After 20 days، the residue (3. 36 mg/kg) still was higher than the MRL. Accordingly، although refrigerated storage increases the durability of the fruit but it reduces the dissipation rate as well.