Study On The Residue Method, Residue Digestion And Risk Assessment Of Tebufenozide On Okra

A modified Qu ECh ERS and liquid chromatography with tandem mass spectrometry(LC-MS/MS)method was established and validated for the qualitative and quantitative analysis of tebufenozide in okra fruit samples.The method showed good linearity with determination coefficients(R~2)>0.99 when adding tebufenozide standard solution at concentrations of 0.01,0.05,0.10,0.50,1.00 and 5.00?g/m L.A weak inhibition effect was observed when the developed method was used for the calculated matrix effect value was 0.88.The limit of detection and limit of quantitation of tebufenozide in okra fruits were 6.7?g/kg and 20.0?g/kg,respectively.When the spiked concentrations were 20,100 and 2000?g/kg,the average recoveries of tebufenozide in okra fruits were between 72.5%and 88.1%with the relative standard deviations of 0.6-6.1%.The dissipation dynamics and terminal residue trials of tebufenozide in okra were conducted in different locations of China including Guizhou,Guangxi,Zhejiang,Anhui,Heilongjiang,and Hubei.The established pretreatment and detection method was applied on the determination of tebufenozide residue in actual okra fruit samples.In the field experiment,20%tebufenozide suspension concentrate was applied on the okra plants at 1 and 1.5 times the recommended doses with 2 and 3 times every interval of 7 days.The terminal residue concentrations of tebufenozide in okra fruits at harvest were<0.020-1.582 mg/kg.Based on the field results,the risk quotients(RQs)of tebufenozide on okra fruits for different ages of Chinese consumers were calculated and far less than 100%.All the above results demonstrated that when spraying tebufenozide on okra fruits in accordance with the recommended procedure,the residue of tebufenozide on okra fruits could not induce health problem.The storage stability experiment of tebufenozide on okra fruits was conducted to obtain data under three different storage conditions(room temperature,refrigerated:4oC,frozen:-20oC).The results showed that the half-lives of tebufenozide were 11.53,26.46,and 301.37 day under the above three conditions,respectively.In frozen conditions,tebufenozide was the most stable in okra fruits.The efficiency and difference of four commonly used home processing methods(washing,boiling,washing+boiling and soaking)on reducing tebufenozide residues from okra fruits was investigated.The average loss efficiencies of washing,boiling,washing+boiling and soaking were 13.35%,15.46%,32.88%and 47.26%,repectively.Therefore,the processing approach of soaking okra fruits with 0.1%acetic acid aqueous solution was the most effective method to reduce tebufenozide residue in okra fruits.This work could provide data support for the safe and proper use of tebufenozide in okra fruits and establish the maximum residue limit of tebufenozide on okra fruits in China.