Transfer of fourteen pesticides from grapes (Vitis vinifera) into wine – Comparison of spiked grapes with grapes treated in the field

Pesticide residues in grapes are usually transferred into the wine during vinification and thus, contribute to a certain human exposure. The objective of the present study was to explore whether spiked samples could be a suitable alternative to the still mandatory field-treated samples in the processing study set-up. Grapes treated with fluxapyroxad in the vineyard and untreated grapes spiked with fluxapyroxad after harvest were processed into wine to check for differences in residual fluxapyroxad. Additionally, the behavior of 13 further pesticides during winemaking was characterized using spiked samples. Grape, must, pomace, and wine samples were analyzed by LC-MS/MS following a QuEChERS extraction protocol. The transfer of fluxapyroxad into wine from field-treated and spiked samples was found to be similar, with processing factors (PF) of 0.31 and 0.33, respectively. A strong correlation between PF and the octanol-water partition coefficient (logK_OW) was identified for 13 of the 14 pesticides present in the spiked samples (R² = 0.89, p < 0.0001). Determined PF were compared with values from the European database of processing factors for pesticides in food, which originate from field-treated samples. No significant differences were found, indicating that field-treated samples are not an absolute necessity for investigating the transfer of pesticides into wine.