Determination And Degradation Dynamics Of Chloropicrin In Soil And Crops

The soil-borne disease is the important disease of the protected area production, especially in continuous cropping. The soil fumigant chloropicrin is effective on the prevention and control soil-borne disease which has been applied in several provinces and cities on the production of vegetables and fruits in China. This paper discusses the chloropicrin's influence on the crop and its growing environment after fumigating the soil, sets up the analytical method of the choropicrin's residue on vegetables, fruits and soil and determination of the final residue and degradation dynamics of chloropicrin in vegetables, fruits and soil is also described.In the first part of this project, in accordance with the NY/T 788-2004 pesticide residue test criteria, we make a field test scheme of four crops in two places in two years, which includes the field test scheme of soil degradation and residual quantity of fruits and vegetables. Then we will apply the pesticide and take samples of vegetables, fruits and soil in different stages and prepare the samples.In the second part of the project, we make a research and comparison the optimal extraction method and solvent of chloropicrin and determine the GC-ECD operational condition of chloropicrin. The research shows that the extraction effect is best when petroleum ether is used to extract chloropicrin in vegetables and fruits by supersonic method and vibration is adopted in soil samples. Determine the chloropicrin residue with gas chromatograph electron capture detector. The chromatographic column has 0.32 inner diameter, column temperature is 70℃and the condition should be maintained for ten minutes. The injector port temperature is 250℃. In the third part of the project, we measure the content of chloropicrin in samples and analyze the data. The result shows that the correlation coefficient in the concentration rang at 0.008～2mg/L was 0.9994. The average recoveries of chloropicrin in vegetables and fruits at 0.02～1 mg/kg fortification level are 92.2%～111%,and the relative standard deviations(RSD) were 1.9%～7.2%.For soil, the average recoveries are 89.5%～111.1% fortified with chloropicrin. The relative standard deviations(RSD) were 3.6%～7.2%. The minimum detectable limits are 0.008mg/kg.The minimum detectable concentration is found to be 0.02mg/kg. Chloropicrin disappears rapidly from soil. Its half-lives in soil are 5.5 days. The residue of chloropicrin in vegetables and fruits including Muskmelon, Strawberry, Ginger, Eggplant and Spinach do not be found by this methodThe main innovations in this project are as follows:1. It is the first time that the degradation rule of chloropicrin soil is under research and the degradation dynamics of chloropicrin field test is conducted in the actual planting environment instead of the simulated environment in the lab.2. It is the first time that the chloropicrin residue research of plants and fruits in the growing and harvest stage is carried out in fruits (strawberry, muskmelon) and vegetables (ginger and eggplant) that are in open ground and protected area.3. The project is an initial survey of testing technology of chloropicrin residue in soil, fruits and vegetables. A method called the GC-ECD testing method has been developed and replaced the traditional spectrophotometer. In this way even greater sensitivity and accuracy is obtained.This project provides theoretical base for directing the reasonable and scientific usage of chloropicrin on soil fumigation, setting up the maximal residue of chloropicrin in food and accurate, sensitive and quick testing technology for the pesticide residue in supervising crops.