The Analysis Method And Application Of Pesticide Residues In Tea And Tobacco

With the development of economy,the food security problem becomes more increasingly serious.Tea is one of important economic export crops in import and export trade in our country,also loved by the people all over the world.In recent years the European Union and Japan put limitation of pesticide residues in tea into a higher standard,China’s export of tea often have been notified due to the problem of excessive pesticide residues,in which kind of situation China’s tea export capacity has been greatly weakened as a result meanwhile it is seriously restricted the healthy development of tea industry in our country.Tobacco is another kind of important economic export commodities as well.In the process of growth,disease and pest happened frequently,people often use a variety of pesticides to ensure the quality of their production and the agricultural income.The use of pesticides may cause pollution to the tobacco;residues of pesticides have a harmful effect on food safety and human health.The LC-MS/MS plays an important role in simultaneous quantitative and qualitative analysis of many kinds of pesticide residues.QuEChERS pretreatment method is famous for its simple,rapid and efficient.QuEChERS pretreatment method has been verified for many years which is a suitable pretreatment process to detect pesticide residues.This article combines the QuEChERS pretreatment method and the LC-MS/MS for quantitative detection of pesticide residues in the tea and the tobacco.The first part of this article used LC-MS/MS to establish a quantitative method to quickly and accurately detect the Imidaclothiz residues in tea,improved the QuEChERS pretreatment methods in,greatly reduced the amount of adsorbent and time cost.Imidaclothiz standard curve established in this paper presented a good linear relationship in 1～300 ng·g-1.Regression equation is y = 2147x + 1836,R2=0.9996.Results show The recovery rates are among 94.04%～100.20%by adding different concentration of Imidaclothiz in tea(100 ng·g-1,500 ng·g-1,3000 ng·g-1).RSD are among 100%～1.70%.Results showed this method had high recovery rate and good precision.LOD is 3.22×10-1 ng·g-1,LOQ is 1.09 ng·g-1,which far less than the maximum residue limit of 3.0 mg·kg-1 regulated in GB 2763-2014.The characteristics of this method are simple,rapid,efficient,strong stability,good repeatability.It is suitable for the residues detection of Imidaclothiz in actual tea sample.The second part of this article pretreated the tobacco samples by QuEChERS pretreatment method,using isotope internal standard method for accurate quantitative detections for 6 kinds of pesticides(Carbendazim,Imidacloprid,Acetamiprid,Metalaxyl,Triadimenol,Triadimefon).A reasonable gradient elution condition was designed(low flow velocity,high proportion of water phase)to separate 6 kinds of pesticides completely which has no interference of each other’s detection.Also the mass spectrum detection conditions were optimized(ion source voltage,collision,etc.),which improves the response values of target compounds in the mass spectrum.The finally experimental results show that the quantitative detection is accurate and reliable,RSD is among 1.48～3.79%,the precision is high.