Determination of Diazinon Pesticide Residue in Tomato Fruit and Tomato Paste by Molecularly Imprinted Solid-Phase Extraction Coupled with Liquid Chromatography Analysis

In the present study, an optimized molecularly imprinted polymer (MIP) was prepared and evaluated as a selective sorbent in solid-phase extraction and analysis in tomato fruit and tomato paste. The MIP was prepared using methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linking monomer, and chloroform as the solvent. Binding properties of MIP was studied in comparison with non-imprinted polymer. MIP was applied, as a sorbent, for extraction and preconcentration of diazinon from tomato fruit and tomato paste. The analytical method was calibrated, in the range of 0.01 to 2 mg kg(-1). The results indicated that the optimized MIP had an excellent affinity for diazinon. The molecularly imprinted solid-phase extraction procedure was developed and optimized with a recovery of 82-116 % in tomato fruit and recovery of 80-110 % in tomato paste. The intra-day variation and inter-day variation values were less than 8.16 % and 9.8 %, respectively. Finally, diazinon content of tomato fruit and tomato paste, in Mashhad city in February 2014, was evaluated using calibrated analytical method. The amounts of diazinon residue in tomato fruit was varied between 0.20 and 0.64 mg kg(-1), whereas the value in tomato paste was varied between 0.02 and 0.31 mg kg(-1). According to our data, the amount of diazinon residue in tomato paste, in Mashhad city, was less than the maximum residue limit (MRL) of diazinon in tomato set by the World Health Organization (0.5 mg kg(-1)), whereas this value was higher than MRL in tomato fruit samples of Mashhad, Nishabur, and Chenaran cities.