Residue Analysis And Primary Dietary Risk Assessment Of Prothioconazole And Its Metabolites In Wheat Plants

Wheat scab is one of the main diseases of wheat in China,which has a great impact on the yield and quality of wheat.Propiconazole is a broad-spectrum triazole thioketone fungicide,which has a wide range of effects and can effectively control many diseases of wheat.However,at present,the absorption and transport mechanism of Propiconazole in plants is unknown,which is not conducive to the further extensive use of prothioconazole.In this paper,the absorption,transport and metabolism of prothioconazole in wheat were studied by hydroponics and spraying,and the residues of prothioconazole and its metabolites in wheat grains and flour in the market and the dietary risk assessment were also studied.The results will provide theoretical basis for wheat food security.The main results are as follows:1 Establishment of the residue method of prothioconazole and its metabolites in wheat substrateUPLC-MS/MS was used to establish a residue analysis method of prothioconazole and its metabolite desulphurizing prothioconazole in wheat roots,stems,leaves,grains,market flour and nutrient solution samples.The minimum detection limit(LOD)of the method is 0.7 μg/kg and 0.08 μg/kg,and the minimum quantitative limits of the method are 2 μg/kg and 0.2 μg/kg.R~2> 0.999,the average recovery rate is 75.8% ～ 117.0%,and the relative standard deviation is 0.5% ～ 7.8%.The results show that this method meets the requirements of pesticide residue analysis,and can be used for the residue analysis of prothioconazole and its metabolites in wheat substrate.2 The absorption,transport and metabolism of propiconazole in hydroponic media by wheat plants.Prothioconazole in hydroponic solution can be absorbed by wheat roots and transported upwards,and the transport capacity of wheat is determined by transport factors.TFleaves/stems(root-to-stem transport factor)is slightly higher than TFstems/roots(stem-to-leaf transport factor),indicating that the transport rate of wheat stems to leaves is faster than that of roots to stems.At the same time,the concentration of prothioconazole in hydroponic solution affects the transport capacity of wheat.The upward transport ability of thiconazole in wheat plants is weak.It is the main accumulation part of prothioconazole in roots,and the enrichment factor of wheat roots(RCF)> enrichment factor of wheat stems(SCF)and enrichment factor of wheat leaves(LCF).Desulfurization prothioconazole is the main metabolite of prothioconazole in wheat,and the trend in wheat roots,stems,leaves and nutrient solution is increasing at first and then decreasing.Desulfurization prothioconazole in wheat plants is mainly concentrated in wheat roots,and the metabolite concentration in wheat stems and leaves depends on the concentration of prothioconazole in the plants.3 Absorption,transport and metabolism of prothioconazole on the leaf surface of wheat plants.The method of foliar spraying showed that prothioconazole could conduct downward transmission in wheat plants,and prothioconazole was mainly concentrated in the leaves of wheat plants,and the concentration of prothioconazole in stems and roots was low,which indicated that the downward transmission speed of prothioconazole in wheat plants was slow.Metabolic thiophanate-prothioconazole reached its peak at 12 h in wheat stems and leaves,and then showed a downward trend after 12 h,and it could be transmitted from roots to nutrient solution.4 Assessment of the residue and dietary risk of prothioconazole and its metabolites in wheat grains and flour in the marketThe wheat grains from 10 regional markets and flour samples from 28 districts and counties in Anhui province were tested.All samples showed that the residues of prothioconazole and its metabolites were lower than the maximum residue limit in China,among which the most residue of prothioconazole in wheat grains was 86.31μg/kg in Hefei,and the most residue of desulphurizing prothioconazole was 12.47μg/kg in Huaibei,Anhui.The dietary risk of thiconazole and its metabolites in wheat grains and flour is less than 5%.The results showed that after application of prothioconazole in wheat plants,the residue in wheat grains was low and the dietary risk was low.