Metabolite of chiral cycloxaprid in solvent and in the raw of Puer tea.

Cycloxaprid (CYC) with a chiral oxabridged cis- structure contains a pair of enantiomers. Enantioselective degradation, transformation and metabolite of CYC was performed in different solvents under light and raw Puer tea processing. The results showed that cycloxaprid enantiomers in acetonitrile and acetone was stable over 17 day, however the transformation of 1S, 2R-(-)-cycloxaprid or 1R, 2S-(-)-cycloxaprid was founded in methanol. The fastest degradation of cycloxaprid occurred in acetone under light, the metabolites were founded with retention times (TR) at 34.83, 15.78 min, which mainly was via the reduce reaction of NO2 to NO, and rearrange reaction to tetrahydropyran. Degradation pathways were via the cleavage of the oxabridge seven member ring and the whole C ring. However, the degradation pathway under raw Puer tea processing was via the cleavage of whole C ring and the cleavage of oxabridge seven member ring and reducing NO2, then it underwent an elimination of nitromethylene and rearrange reaction. This pathway of Puer tea processing was firstly founded.

Enantioselectivity and residue analysis of cycloxaprid and its metabolite in the pile and fermentation processing of Puer tea by ultraperformance liquid chromatography-high-resolution mass spectrometry.

The residues of cycloxaprid enantiomers and metabolites are investigated by ultraperformance liquid chromatography-high-resolution mass spectrometry (UPLC-HRMS) during raw and ripen Puer tea processing. A Chiralpak AG column with chiral stationary phase of amylose tris (3-chloro-5-methylphenylcarbamate) is succeed to separate the 1R, 2S-cycloxaprid, 1S, 2R-cycloxaprid, and their metabolite, which is identified as nitrylene-imidazolidine. It is not conversed 1R, 2S -cycloxaprid into 1S,2R-cycloxaprid during Puer tea processing. The estimated half-lives of the 1R,2S-cycloxaprid and 1S,2R-cycloxaprid are 0.97 and 1.1 h, respectively, and 1R,2S-cycloxaprid decreases more quickly than the 1S,2R-cycloxaprid. During raw Puer tea processing, the half-lives of 1R, 2S-cycloxaprid and 1S, 2R-cycloxaprid are 1.68 h and 1.77 h, but the residue is still detected even if it is over 730 day. However, the half-lives of 1R,2S -cycloxaprid and 1S,2R-cycloxaprid are 0.60 day and 0.63 day during ripen tea processing. The amounts of metabolite are more in raw tea than in ripen tea; the terminal residues are still detected until 730 days during raw tea. A significant enantioselectivity of 1R, 2S-cycloxaprid and 1S, 2R-cycloxaprid is observed during raw tea or ripen tea processing. The degration result shows the enantioselectivity of cycloxaprid in raw or ripen Puer tea processing.