Abstract
According to the high application of imidacloprid insecticide in greenhouse cucumber cultivate, this study researched about daily change of imidacloprid residues in 21 days latent period. The samples were collected from a commercial greenhouse at Mahmud Abad (Mazandaran province, Iran) after treatment in 21 days. Also, the effects of different removing treatments such as washing, peeling and refrigeration storage at 4 ˚C for 48h were investigated in this research. Imidacloprid residue concentrations determined by high performance liquid chromatography (HPLC) with obtained recoveries 104% and limit of detection 0.001 mg l-1. The results showed that maximum concentration of imidacloprid residue detected as in the firstly days after poisoning and this trend decreased till the end of deficiency period. The half-life of imidacloprid that applied on cucumbers was 2.8 days. After 7 days of imidacloprid application, imidacloprid residue concentration was higher than Codex MRL. Additionally, obtained results showed that washing was the most effective way to reduce the imidacloprid residues of the cucumber samples. According to the results of this research, it is recommended that a 7 days waiting period after imidacloprid poisoning and household processing usage are required to lower down the residue levels than Codex acceptable limit to safety consumption of cucumber.

Keywords: Imidacloprid residue, MRL, Greenhouse cucumber, Food safety