Study Of Photolysis Of Chlorothalnil In Capsicum Red And Yellow Pigment Aqueous Soluiton

The method for determination of chlorothalonil and its metabolite4-hydroxy-2,5,6-trichloroisophtalonitrile and m-Phthalodinitrile by high performanceliquid chromatography were established.Research into capsicum pigment aqueoussolution respectively lighted by solar irradiation、ultraviolet lamp and high pressuremercury lamp.The fate of photochemical degradation of chlorothalonil was also studied.4-hydroxy-2,5,6-trichloroisophtalonitrile was identified as the main metabolite and itseffects on metabolic pathway was futher studied.The degradation rates of chlorothalonil exposured in three kinds of lights aredifferent.Chlorothalonil degraded the fastest lighted by ultraviolet lamp,and the solar irradiation group was degraded faster than high pressure mercury lamp group.The half life of each group were1.06h、3h and9.37h,respectively.The degradation rates of chlorothalonil in capsicum pigment aqueous solutionof different concentrations are different too. When lighted by ultravillet lamp,asthe increase of the concentration of red capsicum pigment,the degradation rate increased first,then decreased，When the concentration of red capsicum pigment was10mg/L,the strongest photosensitization effect were appeared,and the efficiencyrate was11.72%.When the concentration of yellow capsicum pigment was under20mg/L,as the increase of the concentration of yellow capsicum pigmen, photodegradation rate increased and then to the highest photosensitization efficiency rate——20.43%when the concentration was20mg/L. When the concentration of yellowcapsicum pigment was above20mg/L,as the increase of the concentration of yellow capsicum pigmen, photodegradation rate decreased.Photosensitization effect turned to photoextinction when the concentration raised to100mg/L.Exposured to the solar irradiation,red capsicum pigment showed photoextinction effect,the efficiency rate changed.The highest value was-54.42%,as the concentration of this pigment was10mg/L.However,the efficiency rate changes were smallwhen the concentration of yellow capsicum pigment changed.When the concentration of yellow capsicum pigment was20mg/L,the strongest photosensitization effectshowed,and the value of the efficiency rate was41.82%;then the concentration ofpigment increased to100mg/L,the photoextinctionrate efficiency rate was-10.21%.In the lights of high pressure mercury lamp,photoextinction effect was showed in red capsicum pigment aqueous solution.When the concentration was50mg/L,photosensitization efficiency rate was2.43.The efficiency rate increased,when theconcentration was above50mg/L,as the concentration increased.In yellow capsicumpigment aqueous,when the concentration of pigment was under20mg/L,the degradation rate increased as the concentration increased.When the concentration was20mg/L described the strongest photosensitization impact and the value of it was23.29%.But the degradation rate decreased as the increase of the concentration of this pigment. The inorganics——Cl-、CO2were found after chlorothalonil’s photolysis.We considered they are produced through the broken of the bones——C-Cl、C-C，respectively.M-Phthalodinitrile can’t be detected through HPLC.We can conclude that chlorothalonil can’t metabolized to m-Phthalodinitrile under the condition of this experiment.Following is the chemical structure of m-Phthalodinitrile:In this experiment,4-hydroxy-2,5,6-trichloroisophtalonitrile was the main metabolite.And the productions of it were different in different capsicum pigments aqueous solutions.It could inhibit the photolysis of chlorothalonil tested by added it to reagent solution.It’s maybe the reason for why chlorothalonil has different degradationrates in different solutions. Following is the chemical structure of4-hydroxy-2,5,6-trichloroisophtalonitrile:...