Degradation Behavior Of Ofloxacin And Flumequine Enantiomers In Mariculture Pond Water

The biological activity and environment behavior of chiral drug enantiomers was usually stereoselective. Therefore, investigation for the degradation behavior of chiral drug in environment could help us to gain insight into the nature of chiral drugs and make a correct assessment for the environment risk. Ofloxacin(OFL) and flumequine(FLU) were commonly-used drugs in aquaculture. In this paper, the detection methods of ofloxacin and flumequine enantiomers in mariculture pond water were established. Otherwise, the stereoselectivity degradation behavior of ofloxacin enantiomers and flumequine enantiomers in mariculture pond water was investigated.In this study, ofloxacin enantiomers and flumequine enantiomers were separated by chiral stationary phase and high performance liquid chromatography. The chromatographic conditions such as mobile phase ratio, the volume of acetic acid and triethylamine(or ammonium acetate) in mobile phase and mobile phase flow rate were investigated. The Waters Oasis HLB was adopted to extract ofloxacin enantiomers and flumequine enantiomers in mariculture pond water. The solid phase extraction conditions such as extractant, the volume of extracting agent and the volume of drip washing were optimized. Finally, we established the detection methods of ofloxacin enantiomers and flumequine enantiomers in mariculture pond water. Results showed that ofloxacin enantiomers reached baseline separation, the retention time of S-(–)-OFL and R-(+)-OFL was 11.3 min and 15.1 min, respectively. The flumequine enantiomers were well separated, the retention time of S-(–)-FLU and R-(+)-FLU was 10.4 min and 11.8 min, respectively. The recoveries of ofloxacin enantiomers and flumequine enantiomers were high than 90%, and showed a good linear between 0.05 mg/L and 5 mg/L. The simple, rapid, accurate and reliable methods established in this paper were available for quantitative analysis of ofloxacin enantiomers and flumequine enantiomers in mariculture pond water.Further, the degradation behavior of ofloxacin enantiomers and flumequine enantiomers in mariculture pond water under natural, sterile and dark conditions was investigated. Results showed that the configuration of ofloxacin enantiomers and flumequine enantiomers was stable and the chiral inversion was not observed in mariculture pond water under natural, sterile and dark conditions. There was no difference between the degradation rate constant and degradation half-life of ofloxacin enantiomers and flumequine enantiomers under natural and setrile conditions and ER was approximately equal to 1. This result suggested that there was no stereoselectivity in the degradation behavior of ofloxacin enantiomers and flumequine enantiomers in mariculture pond water under natural and sterile conditions. However, the degradation rate constant and degradation half-life of ofloxacin enantiomers and flumequine enantiomers under sterile condition was smaller than that under natural condition. The ofloxacin enantiomers and flumequine enantiomers did not degraded under dark condition. This result meant that the microbial community could accelerate the degradation of ofloxacin enantiomers and flumequine enantiomers, but light was the main reason for the degradation of ofloxacin enantiomers and flumequine enantiomers.