The fate of spirotetramat and its metabolite spirotetramat-enol in apple samples during apple cider processing

The fate of spirotetramat and its metabolite spirotetramat-enol in apple samples during apple cider processing was assessed. The residues were determined by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) after each step including washing, peeling & coring, juicing, primary filter, enzymolysis, secondary filter, sterilization, and fermentation. Results showed that the concentration of spirotetramat and spirotetramat-enol residues significantly decreased in apple cider after processing. The processing factors (PFs) of apple samples after each step were generally less than 1 except that the PF of spirotetramat-enol after sterilization was larger than 1. Spirotetramat and spirotetramat-enol were proved to be mostly retained in apple peels. The peeling & coring process caused the loss of 76.4% of spirotetramat and 62.9% of spirotetramat-enol from apples, with the processing factor of peeling & coring at 0.14 and 0.22 respectively.