Analysis of the supersaturation and precipitation process with supercritical CO2

An antisolvent precipitation process was studied in which an ethanol soluti on of the model drug acetaminophen (paracetamol) was dispersed or mixed wit h supercritical CO2 in a nozzle at high Reynolds numbers. The acetaminophen concentrations of the saturated and effluent solutions were measured using an on-line dynamic solubility method. These solubilities allow supersatura tion in the jet (pre-precipitation) and in the reservoir fluid (post-precip itation) to be determined independently. Process conditions of partial and complete miscibility were investigated and it was shown that above the mixt ure critical pressure the crystallization was determined by mixing and prim ary nucleation processes characteristic of liquid solutions. Analysis of su persaturation provided a simple and effective way of process optimisation b ased upon particle size and product yield. (C) 2001 Elsevier Science BN. Al l rights reserved.