Research On The Enantioselective Bioaccumulation Of Trizole Chiral Pesticides In Tenebrio Molitor Larvae

In most cases, enantiomers of chiral compounds have different environmental behaviorsbecause of different bio-chemical processes with environmental system. Therefore, enantiomers ofchiral environmental contaminants need to investigate more deeply. Currently, about40percent ofpesticides are chiral. Most of the chiral pesticides have one or more chiral centers, and differentenantiomers have different bioactivities in chiral environment. With the development of stereochemistry, the researches of chiral pesticides on molecular level are significant. After being appliedin agriculture, enantioselectivity of chiral pesticides would not only occur in chiral environmentsuch as soil and water, but also the difference of chiral enantioselectivity could exist in organismsduring enantioselective bioaccumulation, enantiomerization and so on. In the meantime, chiralpesticides could be harmful to organisms even human beings by bio-magnification through foodchain. As the most widely used fungicide in the world nowadays, triazole pesticides may bedetrimental to environment and organisms due to its enantiomers. In order to study thebioaccumulation effects of diniconazole and tetraconazole of chiral triazole pesticides through foodchain on enantiomeric level, we performed a method of separating and analyzing the enantiomersof triazole pesticides by high performance liquid chromatography tandem mass spectrum fromTenebrio Molitor. Thus, the data could be benefit for evaluating the environmental risk and theinfluence for non-target organisms.In this study, we built and optimized the method of solid phase extraction bond with highperformance liquid chromatography tandem mass spectrum for extracting and analyzing theenantiomers of chiral triazole pesticides from Tenebrio Molitor and its excretion. After removingthe lipid through liquid liquid distribution by n-hexane and acetonitrile and dehydration byanhydrous sodium sulfate, decontaminating by Florisil solid phase extract column. Then gettingthe pesticides and waiting for analysis. Conditions of chromatography and mass spectrum wereoptimized and used Chiralcel OD-3R chiral column after compared with two different chiralcolumns. After being detected, this method was found to be highly sensitive and good separation.The recoveries were in the range of97%to101%. The method was operated easily. In this paper, we investigated the enantiomers of chiral pesticides in wheat bran, TenebrioMolitor and its excretion by using the built and optimized analytical method. Meanwhile, we didthe calculations of ER and BAF values from the experimental data. The results demonstrated thatthere was no obvious enantiomerizaiton of enantiomers and degradation of concentrations ofdiniconazole and tetraconazole in wheat bran while being kept in glass bottles. The exposureexperiment of triazole pesticides suggested that concentrations of diniconazole and tetraconazolecould accumulate rapidly in Tenebrio Molitor in a short time and reached the metabolismequilibrium gradually. Diniconazole could reach the highest point of concentration in one daywhile tetraconazole needed seven days. Compared to the ER values of diniconazole andtetraconazole, it showed that all the ER values diverged from1, which means there wasenantioselective bioaccumulation and enantiomerization existed in the body of Tenebrio Molitor.The BAF values of chiral triazole pesticides in Tenebrio Molitor confirmed that selectivebioaccumulation and enantiomerization occurred. Additionally, it showed that one enantiomer ofthese two chiral pesticides could bioaccumulate preferentially in Tenebrio Molitor. The data of thepesticides from excretion suggested that there was enantiomerization happened and the redundantconcentrations of enantiomers of chiral triazole pesticides would be eliminated from the body ofworm after getting the equilibrium.