Determination Of Heavy Metals And Pesticide Residues In Tobacco Leaves And Its Ecological Environment

Tobacco is a kind of special good. The safe quality of tobacco leaves is getting more and more attention of the consumers. The purpose of modern tobacco agricultural industry is improving the security of tobacco and decreasing the harmful materials content. People are trying to reform a novel planting pattern in order to produce security tobacco leaves. Currently, the key impacts of tobacco leaves security is the content of heavy metal and pesticide residues in tobacco leaves. In this paper, the main tobacco planting areas of Hunan province was chosen as the research object. The heavy metals concentration in planting eco-environment system including soils, fertilizers and irrigation water were analysed and determined. Moreover, the content of pesticide residues and heavy metals in tobacco leaves were also surveyed. The hazardous substances contents in different tobacco planting areas and different parts of tobacco leaves were compared to choice the more security tobacco leaves. Based on the safety evaluation of planting eco-environment and tobacco leaves, it is hoped to develop an effective mode of production for improving planting conditions and tobacco safety. Further, it is hoped to provide a realistic basis and reference for the development of organic tobacco production certification system and production standards. The main contents were as follows:(1) Firstly, the status of heavy metal and pesticide contaminations in tobacco planting eco-environment and tobacco itself, as well as the sources and harms of pollutants were briefly descripted. It was also introduced current analysis and detection technology about heavy metal and pesticides briefly.(2) Tobacco-growing environmental media which was consists of soils, irrigation water and fertilizers were selected as the object for determination. Environmental samples were digested by oxidizing acid. And then ICP-AES was used for the determination of heavy metals (lead, cadmium, chromium, arsenic, copper, zinc, nickel) in samples. By referencing the relevant quality standards of environment, the environmental quality and security of tobacco planting areas were evaluated.(3) Lead, cadmium, chromium, arsenic, copper, zinc, nickel were choiced as the analytical elements. It was selected HNO3-H2O2as acid digestion system to prepare tobacco samples. ICP-MS was used to simultaneously detect heavy metal in tobacco leaves. This method was proved to have higher accuracy and precision which could satisfy the analytical requirement for heavy metal in tobacco leaves. And the quality and security of tobacco leaves were evaluated by comparing a variety of heavy metal limits in tobacco. Based on the pollution situations, effective improvement measures were taken.(4) In the fourth part, a method was developed for rapid determination of metalaxy-M in tobacco by HPLC. Pesticides were extracted from tobacco with hexane-acetone (V:V=2:3). The extract was purified by methylene chloride through liquid-liquid distribution. Then the extract cleaned up on a column packed with neutral alumina. Recoveries of the method were between77.1%-82.3%with the relative standard deviations between4.3%-5.1%. The detection limit of the method for pesticide is0.04mg/kg. The accuracy and precision can satisfy the requirements of pesticide residues in tobacco.