Solvent Type Effect on Preparation of Ethyl Cellulose Microparticles

Abstract

The purpose of this study was to investigate effect of solvent type on solidification rate of ethyl cellulose(EC) microparticles and particle size/distribution of emulsion droplets/hardened microparticlesduring solvent evaporation process using focused beam reflectance measurement (FBRM). ECmicroparticles were prepared by an O/W-solvent evaporation method using various solvents, includingdichloromethane, dichloromethane:methanol (1:1), ethyl acetate and chloroform. The particle size/distribution of emulsion droplets/hardened microparticles was monitored by FBRM. The morphologyof EC microparticles was characterized by scanning electron microscopy (SEM). The transformationof emulsion droplets into solid microparticles for all solvents occured within the first 10-60 min. Thesquare weighted mean chord length of EC microparticles which were prepared using chloroform wassmallest, but the chord counts was no the highest. The chord length distribution (CLD) measured byFBRM showed that a larger particle size mean gave longer CLD and a lower peak of particle number.SEM data revealed that the morphology of microparticles was influenced by type of solvent. FBRMcan be employed for online monitoring of the shift in the microparticle CLD and detect transformationof emulsion droplets into solid microparticles during solvent evaporation process. The microparticleCLD and transformation process was strongly influenced by solvent type.Keywords: chord length distribution, ethyl cellulose, FBRM, microparticle, solvent.