Effects Of Different Curing Processes On The Residues In Tobacco Leaves

Tobacco is an important economic crop in China.The use of pesticides in tobacco production is a commonly used measure to guarantee the quality and yield of tobacco leaves.Pesticide residues are one of the inevitable problems caused by the use of pesticides.Tobacco pesticide residues will be transferred to the human body with the smoke and pose a potential threat to health.As people's health awareness increases,the issue of the safety of tobacco and its products has received widespread attention.pymetrozine,?-cyhalothrin,dimethachlon,thiophanate-methyl,butralin and maleic hydrazide are the six pesticides recommended and widely used in tobacco production.HPLC-LTQ Orbitrap MS method was used for study the effects of flue curing and air curing on the residues of pymetrozine,?-cyhalothrin,dimethachlon,thiophanate-methyl,butralin and maleic hydrazide,and the residues were calibrated by the mass fraction of calcium ions.This paper aims to provide data support for the rational use of pesticides and risk assessment.The main research contents and results of the paper showed as follows:1.A developmental HPLC-LTQ Orbitrap MS method was used for the determination of pymetrozine,?-cyhalothrin,dimethachlon,thiophanate-methyl,butralin and maleic hydrazide,and the method meets pesticide residue testing standards.2.HPLC-LTQ Orbitrap MS method was used for study the effects of flue curing and air curing on the residues of pymetrozine,?-cyhalothrin,dimethachlon,thiophanate-methyl,butralin and maleic hydrazide.Through the change of calcium ion mass fraction,it is clearly showed that consumption of dry matter was massive and dry matter reduced by 29%in flue curing and 52.2%in air curing.All pesticides were degraded during the curing processes,in the flue curing and air curing processes,the six pesticides were degraded by 28.1%-57.9%and 45.1%-72.1%respectively.The degradation rate of pesticides is higher in the air-curing process.3.Based on the changes of pymetrozine,imidacloprid,cyantraniliprole,?-cyhalothrin,dimethachlon,thiophanate-methyl,butralin and maleic hydrazide residues before and after curing,the mechanisms of pesticide degradation in curing processes were explored according to environmental factors in the processes.During the air curing,the pesticide residues are mainly degraded by microorganisms.During the flue curing,pesticides degration was mainly due to microorganisms and physical function.The degradation of pesticides was affected by their chemical structure,and the systemic properties of pesticides are detrimental to microbial degradation.