Dissipation of Spirotetramat and Spirotetramat-Enol in Leaf and Fruit of Grape Variety Red Globe (Vitis Vinifera L.)

Abstract

The dissipation of spirotetramat (sp) and spirotetramat-enol (sp-enol) was determined in leaves and fruit of grapevine (Vitis vinera L.) in a commercial vineyard. sp and sp-enol were extracted with acetonitrile:water, and quantification of residues was done on LC-DAD/MS. The LOQ of this method was found 0.002 mg kg^-1, LOD being 0.001 mg kg^-1 for both. Recovery rates were in the range of 92 to 103% with coefficients of variation less than 9 and 6%, respectively at three levels (0.02, 0.2 and 0.6 mg kg^-1). sp degradation in leaves followed first-order kinetics with R² = 0.84 (p< 0.03). In fruit, only 35% of the original concentration of sp was detected at 5 days after application. These results suggest that residual levels of sp and sp-enol in grapes grown under the conditions of this study pose minimal risk to consumers, since residues did not exceed the limit established by the EPA.