In this study, residues of imidacloprid (Confidor) were measured in greenhouse cucumbers in Mazandaran Province, Iran. Confidor 200 SL was applied at the recommended rate (30.0 g ai ha-1) and its double (60.0 g ai ha-1). Samples were collected at 1 h to 21 days after application and analyzed to determine the content and dissipation rate of Imidacloprid. . Analysis was carried out by the QuEChERS method using HPLCUV. The average initial deposits of imidacloprid on the cucumber fruits were found to be 1.93 and 3.65 mg kg-1 at the single and double dosages, respectively. Results showed that Imidacloprid was rapidly dissipated in cucumbers following a first order reaction kinetics at both application rates. The amount of dissipation in 21 days was 94.48% and 99.18% for, respectively, the single and double dosages. Residues of imidacloprid dissipated below the maximum residue limit (MRL) of 1 mg kg_1 in 3 days. Half-life (T1/2) for degradation of imidacloprid in cucumber was observed to be 3.40 and 2.70 days at the single and double dosages, respectively. A waiting period of 3 days is suggested for safe consumption of cucumber. Also, results showed that the dissipation was dependent on the initial application dose and followed a first order rate kinetics.
