Organotin Fungicide Residues Toadstool Tin And Photodegradation Study

Fentin hydroxide belongs to organotin. It was mainly used as a germicide. At present there is no method for effective analyzing of the residue. In addition to that reasonable application criterion has not set yet.In present study an analytical method was established for determining residue of fentin hydroxide by HPLC under the optimized conditions. Based on a series of field experiments a set of application criteria in terms of potato plant were recommended for 50% fentin hydroxide SC.Photodecomposition is one of the important degradation pathways of pesticides occurring in the potato environment. The process has a direct impact on efficiency and the degradation dynamics of pesticides. Moreover, photolytic products of certain pesticides may also be harmful to environment organisms. In this thesis we investigated the effects of different light sources and other factors, such as, pH value, temperature, solvents, humic acid and pesticide concentration on photodegradation of fentin hydroxide. Possible photodecomposition path-way of fentin hydroxide was determined by using LC-MS/MS.The main results were summarized as following:1.Residue of fentin hydroxide was determined by HPLC under laboratory conditions, fentin hydroxide was extracted by acetone and HC1. The mobile phase was acetrontrile and water (0.05% HC1, 0.4%HCl).Average recoveries for fortified samples were 82.5%~94.9%. Detection limit of fentin hydroxide was 8*10"9g. This analytic method was first reported.2.The residue tests induced that applied fentin hydroxide degraded quickly in field soil, with half-lives at Zhejiang Zhuji longer than those at Fujian Xiamen. Fentin hydroxide degraded relatively slowly in potato plant, with half-lives at Zhejiang Zhuji shorter than those at Fujian Xiamen. The results also indicated that at application rate of 225g ai/h and 45 Og ai/h, no residue was detectected in potato 15 and 30 days from last application. As for soil, the higher the application dosage, the more the application times, and the shorter the sampling interval from last application, the higher the residues were detected. Residue of fentin hydroxide in all potato samples at harvest was lower than O.Olmg/kg, i.e., the maximum residue limit (MRL) temporarily set for potato.3. Results of photolysis of fentin hydroxide induced that;?Photodegradation dynamics of fentin hydroxide under different light sources: Rates of photolysis of fentin hydroxide was in order of: 254nm ultraviolet lamp>280nm ultraviolet lamp>xenon lamp>360nm ultraviolet lamp. When the light wavelength was increased, photolysis rate of fentin hydroxide was decreased.?Photodegradation dynamics of fentin hydroxide under different light strength: When the light strength was increased, photolysis rate wasincreased as well.(3)0ther factors such as pH value ^ temperature^ solvents > humic acid and pesticide concentration all also affect photodegradation of fentin hydroxide.?From information provided by LC-MS and LC-MS/MS, the possible photodecomposition path-way of fentin hydroxide was inferredas follows:___________? Ph3Sn1+___________? Ph2 HSn+ ___________? PhH2Sn+? H3Sn+...