Preparation and optimization of agrochemical 2,4-D controlled release microparticles using designs of experiments

In the present paper, factorial designs of experiments (DOE) were built in the aim of preparing new solid optimized controlled release microparticles charged with the herbicide 2,4-D and, also investigating the influence of some process and encapsulation variables. Composed from mixtures of ethylcellulose (EC) / hydroxy propyl methyl cellulose (HPMC), cellulose acetate butyrate butyryle (CAB) / HPMC and pure CAB as biodegradable polymeric matrices, the microparticles were prepared by emulsification-solvent evaporation technique. Then, the effect of some parameters such as the stirring speed of emulsification, initial drug concentration and polymer concentration were studied. Depending on the selected variables, a large range of microparticles’ size was obtained; from 25 to 208 µm of d and the 2,4-D content reached 69%. Also, different release profiles accompanied with a burst effect were obtained. Finaly, by modelling using Minitab 16.1 software, the main and interactive effects of these variables on the microparticles’ chacteristics (size, drug entrapment and drug release) were evaluated.