Enantioselective Behavior of Flumequine Enantiomers and Metabolites Identification in Sediment

Abstract The enantioselective adsorption, degradation and transformation of flumequine (FLU) enantiomers in sediment were investigated to elucidate the enantioselective environmental behaviors. The results of adsorption test showed stereoselective differences of FLU enantiomers in sediment samples and the adsorbing capacity of S-(-)-FLU and R-(+)-FLU are higher than the racemate, the pH values of the sediment determined the adsorption capacity. Enantioselective degradation behaviors were found under non-sterilized conditions and followed pseudo-first-order kinetic. The R-(+)-FLU was preferentially degraded, and there was significant enantioselectivity of the degradation of FLU. It can be concluded that the microorganism was the main reason for the stereoselective degradation in sediments. The physicochemical property of sediments, such as pH value and organic matter content, can affected the degradation rate of FLU. In addition, the process of transformation of FLU enantiomers in water-sediment system had enantioselective behavior, R-(+)-FLU was preferential transformed. Meanwhile, the main metabolites of FLU in sediment were decarboxylate and dihydroxylation product. This study contributes evidence of comprehensively assessing the fate and risk of chiral FLU antibiotic and enantioselective behavior in the environment.