A Sampling Inspection And Analysis Of The Main Synthetic Pyrethroids Pesticide Residues In Tea

The quality safety of tea is an important subject of market consumption and export of tea. Controlling the pesticide residue in tea is the key method to improve safety quality.Pyrethroid pesticide is a kind of broad spectrum pesticide, which is used often in the prevention and treatment of pest of tree. Through the sampling inspection of pyrethroid pesticides residue in the teas on market, the author analyzes the state of residue and achieved rate of pyrethroid pesticides, further analyzes the relationship between residual levels with areas, season and teas, and discuss the reason for residue of pyrethroid pesticides in tea. These researches will have great theoretical significance to the practice of tea production, especially with regard to control persticide residue in teas, improve the quality safety of teas and instruct the production.The theme of this thesis is the sampling inspection and analysis of pyrethroid pesticide residues. The content of research includes:1. Sampling inspect the main pyrethroid pesticide residues in commercial teas, analyze the overall level and distribution status of pesticide residues in tea samples, and analyze success rate according to the corresponding limits of different standards, namely Maximum Residue Limit(MRL).2. Further compare and analyze the data in groups of origin, season, and type, discuss the reason for residues, and provide theoretical statistics for the instruction of practice.The thesis extracts 126 samples of origins from four cities of two main tea production areas in a certain province, extracts 169 sample from the market randomly, altogether 294 samples. With the help of professional equipment and technology from teas testing laboratory of Center for QualitySupervision and Test of Tea Products in the test and analysis of pyrethrin residues, the thesis makes analysis and comparison, and find the results and conclusion that:1) According to the residues of Biphenthrin, Cypermethrin, Fenvalerate, Decamethrin in 294 samples, the detectable rate is 52.72%,44.56%,42.86% and 17.01% respectively. The measured value mainly appears in the level of 0.000-0.300 mg/kg. The residues of the sample are much lower than national limited values. According to Green Food Standard of Ministry of Agriculture, the achieved rate of Biphenthrin, Cypermethrin, Fenvalerate, Decamethrin is 100%,99.66%,44.56% and 100% respectively, which indicates that the residues of four kinds of pesticide still have some distance to Green Food Standard of Ministry of Agriculture. According to Green Food Standard of Ministry of Agriculture, the achieved rate of Biphenthrin, Cypermethrin, Fenvalerate, Decamethrin is 47.28%,55.44%,57.28% and 82.99% respectively, which means the residues of four kinds of pesticide still have some distance to organic food standard.2) The Pyrethroid pesticide residues from tea samples of different areas of Group E?H?I?JandK indicate that detectable rate of Biphenthrin of Group H is the highest, which is 46.86%, and the number of residue is the biggest, which is 0.874mg/kg. In the sample of the five group, bifenthrin, cypermethrin and deltamethrin all fit national standard. The four groups except Group H fit Green Food Standard of Ministry of Agriculture. Compared with other groups, Group K has a higher success rate to organic food standard of Ministry of Agriculture. The statistics show that, the security of Group H is worse than the security of Group E, I, J and K.3) According to the pyrethroid pesticide residues status from tea samples of different seasons, the detectable rate of pyrethroid pesticide residues is highest in summer, within which the detectable rate of decamethrin reaches 95.24%; the detectable rate of pyrethroid pesticide residues is lower in spring. The pesticide residues of teas from the three season all fit national standard and Green Food Standard of Ministry of Agriculture. According to Organic Tea Limitation of Ministry of Agriculture, acceptability of pesticide residue in spring tea is better than teas in summer and spring, which means that the security of spring tea is better than that of summer tea and autumn tea.4) The pyrethroid pesticide residues from tea samples of different teas indicate that:the detectable rates of pyrethroid pesticide residues in four kinds of tea are all lower than 40%. The detectable rate and residues of yellow tea is much lower than green tea, black tea and dark tea. The four kinds of tea all fit national standard and Green Food Standard of Ministry of Agriculture. According to Organic Tea Limitation of Ministry of Agriculture, the success rate of yellow tea is higher than other teas, which means yellow tea is safer than green tea, black tea and dark tea.5) In 294 samples, isomers of pyrethroid Pesticides have differences out of seasons and teas:the analysis of season indicate, in cypermethrin, Isomer ? in different teas has the lowest coefficient of variation, and Isomer ? has the highest; in deltamethrin, the difference of Isomer ? in different teas is the smallest,and Isomer ? is the biggest; the analysis of different types of tea indicates that in cypermethrin the difference of Isomer ? in different teas is the smallest,and Isomer ? is the biggest; in deltamethrin the differences of Isomer ? and Isomer ? in different teas are all fairly big.