Crystallization is a key unit operation of the pharmaceutical industry. Over 90% of all pharmaceutical products contain drug substances in particle form. In the pharmaceutical industry, there is a significant need to control the particle size distribution and the purification of a drug substance. This is accomplished through the control of crystallization. Unfortunately, the pharmaceutical industry works with new drug substances that are made up of complex organic compounds. These chemical compounds are typically hydrophobic. The chemical complexity of these entities creates difficulties for crystallization. The solutions to these difficulties are sought through the various equipment and techniques used to perform crystallization in the pharmaceutical industry.

In this study, an impinging jet mixer was utilized as a crystallizer within a stirred-tank reactor. The impinging jet mixer was composed of two jet nozzles arranged diametrically opposed to each other with the outlet tips of the nozzles directed to face each other. The jet nozzles were organized in a submerged arrangement within the stirred-tank reactor. A solvent/anti-solvent crystallization method was utilized for an active pharmaceutical ingredient (API), more specifically griseofulvin. The two temperature regulated solutions were pumped through the nozzles at a high linear velocity until they met each other head-on at the impinging point or plane. In order to achieve the goal of producing nanoparticles, a submerged impinging jet system coupled with sonication was utilized.

Such a configuration has been shown to produce micron-sized and nano-sized particles. The particles produced showed greater uniformity in the crystal size distribution, which is a very important parameter of crystallization studies. The impingement collision must occur while undergoing sonication to achieve nanoparticles.