Removal of Residual Solvent after Manufacturing
Manufacturing of substances normally involves the usage of different solvents from which the active ingredient is forced to precipitate or even crystallize. After isolation of the solid material it is of vital importance, both from a regulatory and quality/stability point of view, to remove the residual solvent. However, sometimes it just happens… the solvent molecules resist all reasonable temperature and vacuum combinations applied.
The obvious way is to try different ways of extended standard drying approaches. Drying at longer time at elevated temperature, comparing vacuum and flow of dry gas (like Nitrogen), for instance. However, this approach has a few disadvantages that could give problems or even result in failure e.g.:
- Time might be an issue. Spending weeks just for a simple drying step is not efficient.
- Too high temperatures might accelerate simultaneous degradation processes.
The Adroit way was here to make use of a quite different approach, involving a solid state exchange of the “difficult molecules” with more readily removed solvent molecules as the critical step.
By carefully selecting adequate conditions for the given product it was possible to replace “tough” organic solvent molecules with “kind” molecules during a treatment period of a few hours. A consecutive traditional low temperature drying step then removed the remaining “kind” solvent molecules within another few hours. Thereby this developed process accomplished, in much less than a day, what was previously not possible to attain, even with weeks of “traditional drying approach”.