Degradation Dynamics and Residue Analysis of Four Propiconazole Stereoisomers in "Fengtang" Plum during Storage by LC-MS/MS.

Herein, an accurate and sensitive method was developed for detecting four stereoisomers of propiconazole in "Fengtang" plum by LC-MS/MS. The mean recovery of four propiconazole stereoisomers ranged from 79.42 to 104.10% at three adding levels with reasonable RSD of 1.54-11.68%, and the LOD and LOQ of the four stereoisomers was 0.0005 mg/kg and 0.004 mg/kg, respectively. In addition, the residue and selective degradation of propiconazole stereoisomers in plums were investigated by storage at 20 °C and 4 °C. The half-lives of propiconazole stereoisomeric during storage were 9.49-15.40 d at 20 °C, and 21.00-28.88 d at 4 °C. The degradation of (2R,4R)-propiconazole and (2R,4S)-propiconazole in stored plums was slightly slower than that of the corresponding enantiomers (2S,4S)-propiconazole and (2S,4R)-propiconazole. The total residues of propiconazole were 0.026-0.487 mg/kg in the plum storage period, and the water washing could remove 49.35% to 54.65% of the propiconazole residue in plum. The hardness of plums treated with propiconazole was generally higher than that of control in the middle and late stages of storage. The effects of propiconazole on the total soluble solid content of plums were different at 20 °C and 4 °C. This study provides a scientific reference for the food safety evaluation of the "Fengtang" plum after the application of propiconazole during the storage period.