The drying of small substances is a widely used process step in the laboratory and can be performed in a variety of different instruments.
A vacuum oven is mostly available in the lab environment, but lacks flexibility, needs longer heat-up times and there is a danger of cross-contamination over the gaseous phase. Another method is the classic rotary evaporator, which is limited by the temperature range. The advantage is to dry under steady rotation resulting in faster drying time and homogeneous humidity.
The new Glass Oven B-585 from Swiss company Büchi Labortechnik is especially suitable to dry small sample volumes up to 300°C. In combination with a rotation drive, the instrument can be used to perform aKugelrohr' distillations, a fractionating distillation with a number of glass balls, or to dry powders under movement. A plus is the small bench space used, the quick heat-up time and the excellent visibility of the product: should thermal degradation begin, actions can be taken.
The principle is based on the indirect heating with two concentric glass tubes. On the outer tube, a transparent, electrically conductive coating is applied, which heats up under voltage. Thus, radiation is the relevant heat transfer mechanism resulting in an even heat insertion from all sides.
The angle of the heating tube can be continuously selected from 0° to 90° for an optimal adjustment according to the product volume.
Drying and distillation processes are normally operated under vacuum to decrease the vapour pressure and thus the boiling point. A vacuum pump can be controlled from the Glass Oven to be switched on and off. Up to three temperature and time steps can be programmed to adapt the process optimally on the drying behaviour of the substance.
In addition to the drying setup, further glass assemblies are offered for different applications, such as ball tubes for fractionating distillation, cooling finger for sublimation and now also available a glass insert for a quick and efficient freeze drying. u
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Büchi Labortechnik AG is based in Flawil, Switzerland. www.kugelrohr.com
