Studies On Physical Stability Of Low-melting Pyraclostrobin Suspension System

Suspension concentrate(SC)is one of the most important formulations in modem pesticides with the advantages of low cost, safty and great environmental compatibility. However, the physical stability problems such as larger particles coalescence, thickening, sedimentation and flocculation during the storage of the SC formulation restrict the development of SC, especially higher concentration SC with low-melting pesticide technical.1. In this thesis, we choose low-melting Pyraclostrobin as the research object. The formulation selection and optimization of analyzed method were studied, and influences on the stability system were researched. The theoretical basis was provided for higher concentration SC with low-melting pesticide technical.2. In this paper, the kinds and content of surfactant were screeed. the optimize formula of the35%Pyraclostrobin SC was ascertained as follows:Pyraclostrobin:35wt%; Wetting-dispersant(S+T+F):8wt%; Thickener (xanthan+aluminium-magnesium silicate):0.6wt%; Antifreeze(urea):2wt%; Defoameragent:0.1wt%; Fill acid water to100%.3. In this paper, the internal standard of GC-FID method was used quantitative analysis of Pyraclostrobin Suspension Concentrate (SC). The Pyraclostrobin and internal standard mass ratio was in the range of0.49-5.13.It has wide linear range; Linear regression equation is Y=0.2632X-0.0373; The linear correlation coefficient R had0.9996; The coefficient of determination R2was0.9992. The standard deviation respectively was0.20and0.16and RSD was0.48%and1.01%for testing of different two content Pyraclostrobin SC; The recoveries were in the range of98.28%-101.34%.In this paper, We studied the Physical stability of35%Pyraclostrobin water suspension concentrate. The results showed that35%Pyraclostrobin water suspension is the pseudoplastic fluid, and cohere with Casson model. When the pH value between4to6, milling time above4h and the material temperature above25℃. For the studies of suspension viscosity, the suspension system can keep great physical stability With the increasing proportion of thickener will enhance viscosity and thixotropic of Pyraclostrobin water suspension concentrate, and the viscosity will decrease to showing shear-thinning phenomenon with increasing speed.The35%Pyraclostrobin SC is the higest Pyraclostrobin content Suspension concentrate on the market; and the internal standard of GC-FID method was the foremost used quantitative analysis of Pyraclostrobin SC. The new quality control and analysis method will offer more choice and convenience for the manufacture of the product. Therefore, it has important promotion value and application prospect.