Study On Preparation And Performance Characteristics Of Prochloraz Capsule Suspension

Prochlorazole is a highly effective,low toxic and broad-spectrum fungicide developed in 1977.It has obvious control effect on many crops diseases caused by ascomycetes and half-knowledgeable fungi.It can also be mixed with most fungicides,insecticides and herbicides,and has good control effect.Nowadays,although there are commercial prochloraz wettable powder,suspension agent,seed coating agent and so on,its formulation is still mainly based on emulsifiable oil.At the same time,prochlora z as a protective fungicide has the characteristics of light instability,so it is more light-resistant through formulation processing.Therefore,this paper intends to prepare the capsule suspension of Prochloraz in order to enhance its sustained-release performance,improve the light stability,improve the utilization rate and extend the duration,and enrich the type of prochloraz.Therefore,the preparation and properties of Prochloraz were studied in this experiment.The main research contents and results are as follows:In this study,nano-sized Fe3O4 was prepared by coprecipitation method,and characterized by transmission electron microscopy（TEM）.It was found that the prepared Fe₃O₄ was nearly circular,with a particle size of about 5-10 nm.PEI was successfully modified on the surface of nano-sized Fe₃O₄ to improve its dispersibility in water.The material can be used to prepare Pickering emulsion,which makes the capsule possess excellent properties of the material.The suspension of 5%prochloraz capsules was prepared by interfacial polymerization with iron oxide modified by isophorone diisocyanate（IPDI）and PEI as wall materials and prochloraz as core materials.The optimum formulation was determined by the determination of stability,capsule size and encapsulation efficiency.The formulation and preparation method are as follows:1.Dissolve Prochloraz in xylene and add emulsifiers 33#and 500#and IPDI in a ratio of 3:2 to for m oil phase.2.Disperse PEI-modified ferric oxide in a small amount of acetic acid solution for reserve.3.gradually add the oil phase into the aqueous phase to form the emulsion.4.adding PEI modified iron oxide dispersing solution in emulsion and 6h at 10 degree.Finally,adding xanthan gum and dispersing evenly,the suspension of prodrug can be prepared.A method for the determination of Prochloraz by high performance liquid chromatography was established.The regression equation between prochloraz concentration and peak area was y=124.28x+102.11,and the correlation coefficient R2=0.9997.The average recovery rate of the method was 91.32%,ranging from 70%to110%.The high accuracy standard deviation of the method was 2.14 and the coefficient of variation was 2.2.The suspension agent of 5%prochloraz capsule was characterized by biomicroscopy,transmission electron microscopy,atomic force microscopy and laser particle size analyzer.The results showed that the surface of the capsule was spherical and the particle size was 101.8 nm.Changing pH would affect the particle size of the capsule.The particle size of the capsule was 140 nm in acidic environment and 115 nm in alkaline condition.The content of Prochloraz in the preparation was about 4.87%,t he drug loading was about 30.35%,the encapsulation efficiency was about 89.01%,the suspension rate was about 95%,the dispersibility was excellent,the thermal storage stability was general and the cold storage stability was good.Prochloraz capsule suspension has smaller contact angle and larger adhesion work,and good wettability.Capsules can significantly reduce the photolysis rate of Prochloraz and have a certain recovery potential.The release properties of Prochloraz capsule suspension were tested under different indoor conditions.Experiments showed that prochloraz capsule suspension had sustained-release properties.Capsules release faster in acidic environment.When the pH of the release medium becomes acidic,the capsule has a sudden release phenomenon,which indicates that the capsule is sensitive to acid.By fitting the release kinetics equation,it was found that the release curves of Prochloraz capsule suspension under different conditions were higher than those of Peppas model,and accorded with the characteristics of first-order release.Calculating the value of N in Peppas model,the diffusion index n is between 0.43 and 0.85,so its release mechanism belongs to Fickian diffusion and skeleton erosion.The inhibition of 5%prochloraz capsule suspension and 25%prochloraz emulsifiable concentrate on Citrus anthracnose was determined under different conditions.The results showed that the inhibition rate of Prochloraz capsule suspension increased first and then decreased.The increase of inhibition rate was related to the sustained release of prochloraz.The reason for the decrease of inhibition rate was the photolysis of prochloraz.On the 7th day,the inhibition rate of Prochloraz capsule suspension was higher than that of emulsifiable oil,and the inhibition efficiency of Prochloraz capsule suspension was higher under acidic conditions.The results showed that 5%prochloraz capsule suspension had good sustained release and photolysis resistance,and had good effect on prolonging the duration o f Prochloraz and preventing photolysis.