The Study On Chiral Separation Of Fenvalerate And Their Stress Effects On Platymonas Subcordiformis

This work has developed a quick method for chiral separation of fenvalerate enantiomers using Microemulsion Electrokinetic Chromatography(MEEKC).By investigating the stress effects of fenvalerate and its enantiomer s,s-fenvalerate on Platymonas subcordiformis,it is known that the chiral separation of fenvalerate enantiomers can reduce the emitted amounts of fenvalerate into the environment and is also valuable for the protection of food chain and the food safety.Four fenvalerate enantiomers were resolved in the baseline separation by MEEKC usingβ-cyclodextrin as a chiral selector.The electrophoretic experiment parameters such as the buffer components,buffer concentration and pH,the components and concentration of microemulsion,and the concentration ofβ-cyclodextrin were optimized.An uncoated fused-silica capillary of 75μm i.d and length of 57cm(effective 50cm) was used.The capillary temperature was maintained at 25℃,and the sample was separated at 15KV.The optimal separation conditions were achieved with a background electrolyte of 5mmol/L NaH₂PO₄+10mmol/L borax (pH6.5),and the microemulsion of 140mmol/LSDS+30mmol/L n-heptane+300 mmol/L.1-butanol.Further,the peaks of s,s-fenvalerate was confirmed by internal standard method in this electrophoresis conditions.This work also evaluated 96 hours acute toxicity of fenvalerate and s,s-fenvalerate for Platymonas subcordiformis.According to the experimental results, the 96hEC₅₀ of fenvalerate was 39.2mg/L and the 96hEC₅₀ of s,s-fenvalerate was 5.9mg/L.The former was 6.6 times high than the latter.The toxicity of s,s-fenvalerate was greater than fenvalerate.The physiological indexes of Platymonas subcordiformis such as chlorophyll a,soluble protein,SOD,and POD were determined.Among them, SOD had the maximal reduction rate after stress.It was indicated that the stress effects of fenvalerate and its enantiomer s,s-fenvalerate to Platymonas subcordiformis mainly expressed on the suppression of the enzyme.