Enantiomeric Resolution And Zebrafish Embryonic Toxicity Of Fenamiphos And Transformation Products

The structures of transformation products are familiar with parent contaminants, as well as their physicochemical properties. However, their ecological toxicological effect and environmental fate are different. Especially, there are enantiomeric differences in most chiral compounds. It increases their potential and unknown environmental risk. Therefore, study of the enantiomeric separation and analysis about parent compound and transformation products on environmental and ecological toxicological of chiral compounds for the ecological risk assessment is of great significance. Fenamiphos is typical organophosphorus chiral pesticide, has been widely used and frequently detected in water and soils. Its transformation products are sulfoxide and sulfone. In this work, the chiral resolution and zebrafish embryonic enantiomeirc toxicity of fenamiphos, fenamiphos sulfoxide and fenamiphos sulfone were studied.Enantiomers of fenamiphos, fenamiphos sulfoxide and fenamiphos sulfone were separated using normal phase HPLC with Chiralpak AD-H column,0.8mL/min, mobile phase was n-hexane/ethanol (95/5,88/12,65/35, V/V),256nm. The type and composition of modifiers in mobile phase on enantiomeric separation was carried out, and the enantiomer absolute configurations were determined. The recovery and variation coefficien of soil and water sample was84.2%～92.8%and was3.5%～5.8%, respectively.A kind of enantiomeric simultaneous analysis method of three compounds on normal HPLC was established. The analysis condition was as follows:Chiralpak AD-H column;25℃; n-hexane/2-propanol/water (87/13/0.02, V/V/V);0.8mL/min. The eluted order was R(+)-fenamiphos,S(-)-fenamiphos, SR*PR(+)-fenamiphos sulfoxide, SS*PR(-)-fenamiphos sulfoxide, R(+)-fenamiphos sulfone, SR*PS(+)-fenamiphos sulfoxide, S(-)-fenamiphos sulfone, SS*PS(-)-fenamiphos sulfoxide. The methanol was reliable for residual analysis of the compounds.Fenamiphos and fenamiphos sulfone has higher zebrafish embryonic death ability, and fenamiphos sulfoxide has a lower toxicity to zebrafish embryos. Fenamiphos, fenamiphos sulfone and fenanmiphos sulfxide’s48h LC50value was2.17mg/L,9.23mg/L and3.27mg/L. The malformations of embryos were differene, indicatting that the toxicity mechanism was different. The enantiomeric difference toxicity of three compounds to zebrafish embyoys was obvious:R(+)-fenamiphos and S(-)-fenamiphos’s48h LC50value was1.55mg/L and4.93mg/L; SS*P*(-), SS*PS(-), SR*PS(+) and SR*PS-fenamiphos sulfoxide’s48h LC50was4.00mg/L,3.85mg/L,33.27mg/L and42.04mg/L; R(+)-fenamiphos sulfone and S(-)-fenamiphos sulfone’s48h LC50was2.53mg/L and7.45mg/L. The relative contribution of enantiomers on toxicity was different, joint toxicity of fenamiphos and fenamiphos sulfone enantiomers showed simple additiony effect and joint toxicity of fenamiphos sulfoxide’s enantiomers/diastereoisomers showed antagonism effect.