Persistence And Degradation Of Exfenvalerate And Deltamethin In Tobacco Leaves During The Flue-Curing And Storage Process

Tobacco is one kinds of food, pesticide residues in tobacco affect the health of consumers.Exfenvalerate and Deltamethin are two kinds of pesticide which were efficient, broad-spectrum and poisoning, and recommended by State Tobacco Monopoly Bureau. Studying the pesticide degradation and final residues during tobacco Flue-Curing and storage process, plays an important role in controlling pesticide residues in cigarettes, determining the reasonable storage time and Guaranteeing the health of smoking consumers.At present , few people study the pesticide degradation trends and final residue during tobacco Flue-Curing and storage process . Exfenvalerate and Deltamethin were as the object of study, used the gas chromatography (GC) method, studied their degradation and final residue during tobacco Flue-Curing and storage process. The main findings are as follows:1 The research consummated the Exfenvalerate and Deltamethin determination method of domestic and external, established one kind of Exfenvalerate and Deltamethin determination method which extracted with methyl cyanide and water component solvent , purified with the Florisil column , measured with Agilent the 6890N gas phase chromatograph (with ECD). The results indicated that this examination method had the good reliability.2 The research had determined degradation equation of Exfenvalerate and Deltamethin during tobacco Flue-Curing Process; had obtained that different residue of the same pesticide had different half-life and degradation equation, residues in the greater, the longer half-life; had determined Exfenvalerate and Deltamethin degradation equation on different storage conditions; and had obtained that the same pesticide had different half-life with different storage conditions in the same year, they all had the longest half-life storing in dry dark storage conditions at low temperature(6-8℃), and had the shortest half-life storing in the higher temperature (30℃),dry and dark condition.3 The research had determined the relations between the spraying density, quantity and final residues. Certain surface , the residue increased with spraying concentration,spraying density is higher during tobacco growth period, final residue is higher during tobacco Flue-Curing and storage process; the residue also increased with spraying quantity, spraying quantity is more during tobacco growth period, final residue is also higher during tobacco Flue-Curing and storage process .4 According to the State Tobacco Monopoly Bureau recommends ways to use, Exfenvalerate and Deltamethin final residue in tobacco leaf was not higher than MRL(Exfenvalerate 10 mg/kg, Deltamethin 2 mg/kg).This experiment enlarged density (Exfenvalerate 0.12 mL/m2, Deltamethin 0.10 mL/m2) and increased spraying number (Flue-Curing Process 4 times, storage 6 times), after Flue-Curing, Exfenvalerate final residue was not higher than MRL(10 mg/kg); but Deltamethin final residue was higher than MRL(2 mg/kg); after Stored 360 days, two kinds of pesticide residue were lower than MRL(Exfenvalerate10 mg/kg, Deltamethin2 mg/kg). With Exfenvalerate and Deltamethin widely used in tobacco production, Insect Pest Resistance to Pesticides had increased, when the Helicoverpa assulta is serious,increasing the spraying density and number ,the final residue in tobacco leaf was not higher than MRL after Stored one year.