| Pesticide pollution problem has already become one of the major issues in food safety in China even all over the world.There are already more than 1,000 pesticides,and new pesticides are being developed and applied constantly.To ensure the healthy diet of people and break the barriers of international trade,it's necessary to pay more attention to the determination of pesticide residues in agricultural products.Spice material refers to a kind of natural plant products with typical flavor or certain essential oils extracted from plants(flowers,leaves,stems,roots,fruits,or whole grass,etc.).Common spices include:Zanthoxylum bungeanum Maxim.,star anise,cinnamon,pepper,cumin,myrcia,and dried tangerine or orange peel,which have wide application in our life.Spices are frequently used in people's daily diet,it can not only promote appetite and improve the food flavor,but also has the function of sterilization and anticorrosion.In addition,spices also have some certain medicinal value.Compared with common fruits and vegetables matrix,the components of spice matrix are more complex.It includes various volatile oils,alkaloids,amides,lignans,coumarins and so on.At the same time,this matrix usually has higher oil content and higher pigment content.The matrix interference could not be effectively removed by pretreatment.As a result,the instrument cannot achieve accurate quantitative and qualitative in the process of detection.In this study,automatic QuEChERS equipment was used in combination with liquid chromatography triple quadrupole tandem mass spectrometry to develop a method of multiple pesticide residues detection in two common spices.The method can be applied to the pesticide residues detection of spices,provide technical support and reference for the detection of technology.The main results are as follows:(1)A method for the determination of 191 pesticide residues in Zanthoxylum bungeanum Maxim.was established by using automatic QuEChERS combined with high performance liquid chromatography-triple quadrupole tandem mass spectrometry(LC-MS/MS).Samples were made by the automatic system and detected by LC-MS/MS.The detection scanning was in electrospray ionized ion and dynamic multiple reaction monitoring(DMRM)mode and the matrix matching external standard method was used for quantitative analysis.The experimental results showed that 191 target pesticides exhibited great linear relationships within their respective linear ranges,and linear correlation coefficients(R2)were all greater than 0.995.The limits of detection(LOD)were in the range of 1-5 ?g/kg and the limits of quantification(LOQ)were in the range of 2-20 ?g/kg,At 10 ?g/kg,20 ?g/kg and100 ?g/kg levels,the recoveries range of 191 pesticides were 70.89-107.6%,70.49-116.44%and 70.88-119.02%,the relative standard deviations(RSDs)of each additive level were less than 13.9%.The results showed that the method was fast,accurate and reliable,and realized the automation of QuEChERS pre-treatment method,which was suitable for the rapid screening and detection of various pesticide residues in Zanthoxylum bungeanum Maxim.(2)A method for the determination of 216 pesticide residues in myrcia was established by using automatic QuEChERS method combined with liquid chromatography-quadrupole time-of flight mass spectrometry.Samples were made by the automatic system and detected by LC-MS/MS.The detection scanning was in electrospray ionized ion and dynamic multiple reaction monitoring(DMRM)mode and the matrix matching external standard method was used for quantitative analysis.The experimental results showed that 216 target pesticides exhibited great linear relationships within their respective linear ranges,and linear correlation coefficients(R2)were all greater than 0.995.The limits of detection(LOD)were in the range of 1-5 ?g/kg and the limits of quantification(LOQ)were in the range of 2-20 ?g/kg.At 10?g/kg,50 ?g/kg and 100 ?g/kg levels,the recoveries range of 216 pesticides were70.4-112.5%,70.3-107.0% and 72.4-95.9%,the relative standard deviations(RSDs)of each additive level were less than 13.9%.The results showed that this method was fast,accurate and sensitive,and could be applied to the high-throughput qualitative screening,accurate quantification of multi-pesticide residues in myrcia,and extended to the high-throughput screening of multi-pesticide residues in other spices.(3)The established screening method was applied in Zanthoxylum bungeanum Maxim.and myrcia for pesticide residue analysis and qualitative screening,there are low concentrations of Thiophanate-Methyl,Tebutam,Etoxazole and other pesticide residues in the marketed Zanthoxylum bungeanum Maxim.Among them,Etoxazole detection concentration up to 50.34 ?g/kg.The species and quantity of pesticides in myrcia were less than in Zanthoxylum bungeanum Maxim.,and a total of 6 pesticide residues were detected in the myrcia samples.More attention should be paid to pesticides with higher detection frequency and higher concentration. |
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