Developing Improved Lyophilisation for HPLC FractionsSource: SP Scientific
Drying high performance liquid chromatography (HPLC) purification fractions, principally comprising water and acetonitrile, is a routine yet essential task in many laboratories. The requirement is to dry the samples to a powder form, such that samples can be accurately weighed, easily sub-sampled and redissolved. Freeze drying is therefore the preferred technology, however, large scale traditional freeze driers may have difficulty processing the organic solvents which can boil out of the samples and damage the vacuum pump. Actelion Pharmaceuticals adopted the fast lyophilisation (LyoSpeed™) methodology developed by Genevac1, and implemented this using the Genevac HT-12 centrifugal evaporation systems. The LyoSpeed method concentrates the organic solvent with the centrifuge controlling boiling preventing sample loss. The system then drains the organic solvent from the condenser and then lyophilises the remaining water. This works well for hydrophilic samples but problems may arise where the sample cannot dissolve in only water – when the organic solvent is removed - the sample then crashes out and/or forms an oil. Such samples require further processing to achieve the desired dry powder form.