Study On The Boundary Layer Between Apple Pericarp And Residue Pesticide

The apple pesticide residue question has become the chief obstacle in affecting our country apple industry internationalization. At present, study samples of apple pesticide residue stem mainly from the entire apple or some parts (sarcocarp and pericarp), because the results from these have the generalization. However, the apple residue pesticide mainly exists in the apple pericarp. Therefore, the careful research to pesticide residue of apple pericarp provides the theory instruction and the design basis to the pesticide residue and the elimination research.The paper takes boundary layer analysis of the residue pesticide on the apple pericarp as a key point. Firstly, use the fluorescence microscopic to analyze the effect of apple pericarp by argon ion carving. Next, use XPS to scan and analyze the clean apple pericarp and apple pericarp with pesticide (oxygen rogor or dichlorovos). Through the contrast we obtain boundary layer information of the apple pericarp residual pesticide. The results as follows:(1) The fluorescence micrograph demonstrates that the argon ion carving to apple pericarp can carry on peeling the apple pericarp layer by layer, the peeling is even, and the effect is obvious.(2) The three element's relative content of the carbon, the oxygen, and the nitrogen in different apples and different parts in the same apple has little difference. The relative content of carbon is increasing as the depth changes, whose tendency is stable to down level. And the carbon relative content in O-C=O, C=O and the C-O structure increases obviously from sarcocarp to pericarp after the sixth argon ion carving.(3) Comparisons by XPS between argon ion carving apples and clean apple demonstrate the cutin area boundary between pericarp and pesticide. Moreover, longitudinal change rule of used pesticide density is exponential decreasing form progressively as well as rule of different time in using the pesticide.(4) XPS can analyze the phosphorus metabolism structure of residue oxygen rogor and dichlorovos in the apple pericarp. The results show that phosphorus in the oxygen rogor is double peaks. Besides oxygen rogor, little virulent production is formed O, O, S- trimethyl phosphate. Under the condition of the same quantity pesticide used, the residue quantity of oxygen rogor residue is bigger than that of dichlorovos. In the residual dichlorovos the phosphorus still exists in the form of P=O key's phosphoryl compound.Through the analysis of argon ion carving and pesticide residue of apple pericarp boundary by XPS, we can draw up the pesticide distribution condition and the structural change in the microscopic angle preliminary. The analysis results provide the essential data for the pesticide residue research, and provide the rationale of the new research and the method of eliminating residual. The method in the paper also expands the space for XPS applied in the apple pericarp as well as physics methods used in the biomass.