Dynamics and residues of mixed formulation of fenamidone and mancozeb in gherkin field ecosystem.

The dynamics and residues of mixed formulation of fenamidone and mancozeb in a gherkin field ecosystem were investigated. The quantification was performed using gas chromatography-electron capture detection (GC-ECD) and UV-vis spectrophotometry for fenamidone and mancozeb residues, respectively. The method was validated using blank samples spiked at three levels and the results showed that recoveries ranged from 92 to 98 and 90 to 96 percent with relative standard deviations (RSD) ranging of 0.78-5.9 and 2.04-4.41 percent for fenamidone and mancozeb, respectively. The compound degradation followed a first order kinetics with half-lives of 2.8-2.82 and 2.02-2.26 days, for fenamidone and mancozeb, respectively. Pesticide residues in fruit were below the EU maximum residue level (MRL) after 10 days for fenamidone (0.02 µg/g) and just after treatment for mancozeb (2 µg/g). These results can be utilized in formulating the spray schedule and safety evaluation for these pesticides in gherkin.