| abstract |
A method for forming particles of a substance, comprising: (a) preparing a solution or suspension (6) of the substance in a vehicle; (b) introducing the solution or suspension into a particle formation vessel (1) via a fluid inlet means (5); and (c) introducing with the solution or suspension a primary supercritical fluid (8-10) capable of acting as an anti-solvent for the substance, under conditions which allow the supercritical fluid to extract the vehicle from the solution or suspension and hence cause the formation of particles of the substance; wherein a (preferably supercritical) secondary fluid (12) is introduced into the particle formation vessel with the solution or suspension and/or the primary supercritical fluid, upstream of or at the point at which particle formation occurs, the secondary fluid (12) having a lower capacity for extracting the vehicle than that of the primary supercritical fluid. The invention also provides the use of such a secondary fluid (12) for the purpose of eliminating, at least substantially, blocking of the fluid inlet means and/or of the fluid supply line(s) to the inlet means, in such a particle formation method, and/or for the purpose of reducing pressure fluctuations in the fluid inlet means and/or fluid supply line(s). |