Dissipation of Propamidine Fungicide Residues in Greenhouse Tomato

A method of reverse phase high performance liquid chromatography (RP-HPLC) was established to analyze the dissipation of propamidine residue in tomato. Residue of propamidine was extracted from tomato using methanol buffered and determined by RP-HPLC with UV detection at 262 nm. The results showed that the average recoveries of the samples fortified with propamidine at the concentration range of 25 to 300 mg kg-1 ranged from 87.972 to 106.341% with a relative standard deviation ranged between 0.169 to 3.503%. Initial deposit ranged from 2.45 to 5.70 mg kg-1. The dissipation of propamidine in tomato followed the first order kinetic equation. The dissipation rate constants in tomato treated with recommended and double recommended dose applied at 4 times and 2 times ranged from 0.110 to 0.151 days, and the corresponding half-lives from 4.589 to 6.300 days. At the day 14 after the last application the residue concentrations of propamidine in tomato ranged from 0.42 to 0.54 mg kg-1 from the two blocks for all treatments. These propamidine residues dissipated below the limit of detection of 0.07 mg kg-1 28 days after the last treatment. The results presented in this work and the low toxicity of propamidine for environment proved that propamidine will not pose any residual toxicity problem after 14 days of application and tomato fruits could be used safely for human consumption.