Study On Photodegradition Of Chlorothalonil In Green And Red Pepper Pigment In Aqueous Solution

Residues analytical methods of chlorothalonil in aqueous solution were established. Photodegradition of chlorothalonil in different concentration of green and red pepper pigment in aqueous solution, as well as different initial concentration of chlorothalonil under the high-pressure mercury lamp, sunlight and the ultraviolet lamp were studied in this paper. We also had a sight on the probable photolytic products of chlorothalonil.Residues of chlorothalonil were extracted from water with N-hexane acetate and determined by GC-ECD. The limit of detection of chlorothalonil was0.01mg/L.The average recoveries and coefficient of variations of the method were80.62%-93.99%,2.243%-3.247%. These results showed that both the methods accorded with demands of residue analysis of pesticides.The sequency of photolytic rate of chlorothalonil under the high-pressure mercury lamp, sunlight and the ultraviolet lamp was:the ultraviolet lamp> sunlight> the high-pressure mercury lamp. Under the high-pressure mercury lamp, red pepper pigment had a decreasing degradation effect on the photolytic rate of chlorothalonil, while green pepper pigment had a increasing degradation effect. Under sunlight and the ultraviolet lamp, both of two kinds of pepper pigments had a increasing degradation effect on the photolytic rate of chlorothalonil, and it was positively correlated with concentration of pigment. Under the ultraviolet lamp, the photolysis reaction of chlorothalonil accorded with first order reaction kinetics and its photolytic rate was negatively correlated with its initial concentration.