Variosol ® technology is based on the physical capability of rapidly expanding CO2 to adsorb heat, thus inducing rapid cooling and controlled crystallization of sprayed or atomized materials. In Variosol process, active molecules and excipients are melted, dispersed or dissolved in a feeding vessel, under a gaseous CO2 or other inert gas atmosphere, and subsequently atomized through a nozzle, under controlled pressure and temperature, into a spraying tower. Here the dense, expanding CO2 enters in direct contact with the sprayed product, cooling it down to temperatures well below 0ºC, and generating very fine particles. Particles size, surface and bulk properties can be controlled and modified depending on the process conditions and the materials used.

Variosol ® principle: expanding dense gas around critical point

Rapid CO2 expansion subtracts heat and induces density changes.
In direct contact with atomized product, expanding CO2 rapidly cools and crystallizes product in micronized form.

Critical Point CO2:
T = 31.2 oC; P = 72.8 bar

Conditions compatible with pharmaceutical processing.

No need for sophisticated equipment for extreme conditions.

Atomization by near-critical fluid (dense gas) expansion

Near-critical CO2 as particle size reduction agent and refrigerant
  • The expanding CO2 atomizes the sprayed mixture into microscopic particles while simultaneously cooling it.
  • The desired crystallization temperature can be adjusted to almost any value around or below the triple point of CO2 through the mixture ratio of the sprayed mixture and gas.
  • Adjusting the mixture ratio, and through the nozzle geometry and type, particle size distribution and morphology can be influenced.
  • Atomization and crystallization of low MP and low Tg materials

View of the spraying process

Variosol ® is owned by Messer Group GmbH, protected by several patents, and exclusively licensed to SiTec PharmaBio for pharmaceutical, biotech and life-sciences applications