Evaluation of Diazinon and Oxydemeton-methyl Residues by GC/NPD in Tomatoes Grown in Kerman Greenhouses

Pesticides are one of the major pollutants in the environment. The residue of pesticides has been reported to be at a critical level in agricultural crops, especially in greenhouse crops. Tomato is considered as an important vegetable in Iranian food basket and is produced in fields and greenhouses. So, the current study aimed to assess diazinon and oxydemeton-methyl levels in tomatoes sampled from five Kerman greenhouses. The extraction of these pesticides was carried out by mixture of dichloromethane and acetone. The extracts were cleaned up according to solid-phase extraction method. The pesticide residue was then determined by capillary gas chromatography and through nitrogen-phosphorus detection. The obtained results showed that the recovery level was estimated at 86.7 and 84.3% with RSD≤ 16.0%, the limit of detection was estimated at 0.026 and 0.035 mg kg-1, limits of quantification stood at 0.091 and 0.115 mg kg-1, and linearity r2= 0.997 and r2= 0.989 for diazinon and oxydemeton-methyl, respectively, in tomato samples. The mean of diazinon residue was calculated at 0.276 mg kg-1, which was 5.52 times the national Maximum Residue Limit (MRL= 0.05 mg kg-1), and the mean of oxydemeton-methyl was 1.624 mg kg-1, being 1.624 times the MRL (1 mg/kg).