Effects of expansion parameters on characteristics of gemfibrozil powder produced by rapid expansion of supercritical solution process

Micronization of gemfibrozil particles was carried out by the rapid expansion of a supercritical solution process with CO2 as the solvent. In this work, effects of spray distance (2.5, 5.5, 10.5 and 15 cm), nozzle type (capillary and orifice nozzles), nozzle diameter (0.25 and 0.5 cm for orifice diameter) and temperature of expansion vessel (10, 26, 30 and 65 °C) on the characteristics of gemfibrozil particles were studied. In addition to traditional sampling methods, an electrostatic precipitation was also carried out as sampling method for collection of the RESS produced particles. Based on our knowledge, this study on the effect of charged plate sampling method (electrostatic sampler) in the RESS process is the first study of this kind. The smallest mean size of gemfibrozil particles produced by orifice nozzle with 0.25 mm inner diameter, 10.5 cm spray distance and 65 °C temperature of expansion vessel was about 0.6 μm. The largest mean particle size of gemfibrozil particles was 2.1 μm produced by a capillary nozzle with a spray distance of 5.5 cm. The results showed that the spray distance and the nozzle type were the efficient parameters on the morphology of precipitated particles but nozzle diameter had little effect on the mean size of precipitated particles.