Genevac HT-8 & HT-12 Series II Evaporating Systems
04-4541
Issue 1-9 – June 2008
Page 59 of
64
Lyophilising HPLC Fractions
The best optimised evaporation method has the following stages:
1. Follow stage 1 of the ‘Drying HPLC Fractions’ method to remove the organic solvent
2. Cool the samples – concentrating some of the water without any heat input
Use controlled pressure 8mbar to boil away some of the water without any heat input, this will cool the
holders and help achieve good freezing in the next stage. It may be possible to concentrate more
water at this stage – if you have very large or water heavy fractions please contact Genevac for advice
3. Freeze all the samples using high vacuum
Run the system at Full vacuum with no heat for 1 hour
4. Lyophilise the samples to dryness, using heat if possible to speed the process up
Run the system at full vacuum, trial and error will determine the length of time that Lyophilisation takes
See appendix B for programming details.
Please contact your local Genevac representative for further details on run times, alternatively please e-mail
Notes on Lyophilisation
•
Setting up the fast lyophilisation method takes some trials to establish a fully functioning process, it
may take several attempts. It is a very useful to have the Genevac Data Logging software running on
an adjacent laptop or PC to collect the evaporation data which can then be sent to Genevac as an aid
providing remote assistance.
•
Always use both sample guard probes, placing one in the sample holder to control the temperature,
and one in a central sample to provide feedback on the process. This is essential during method
development, this will tell you if your sample has frozen or not, and when lyophilisation has ended.
•
Always fill your sample holders with samples when doing lyophilisation, part filled holders may not
freeze.
•
This method will not be able to lyophilise samples that are grossly insoluble in water – these will crash
out once the organic solvent has been removed from the mixture.
•
Never use Auto-Defrost and Drain on the final stages of a lyophilisation method – solvent vapour from
the condenser may re-enter the samples and cause the powder to collapse. Feedback from some
Genevac users suggests that this is worse when samples are TFA salts, where as HCl salts are
reportedly more robust. These observations have not been proven. Only defrost the condenser once
you have removed your samples from the system.
Drying Mixed High and Low Boiling Point Samples
The actual method that you will need depends on the solvents that you have in the mixture. We have outlined
a mix of DMF or DMSO and DCM in this illustration. For other details of mixtures, please contact Genevac.
1. Use Variable Dri-Pure™ to prevent bumping
Ramp from 750mbar to 70 mbar in 55 minutes
2. Remove the DCM, and collect it all in the cold trap
Evaporate the DCM at 65mbar
3. Auto-Defrost and Drain – this will be a short defrost and will drain the organic solvent from the
condenser, allowing high vacuum levels to be achieved for drying the high boiling point solvent.
4. Evaporate the high boiling point solvent
Use full vacuum – end the method using heat flow
5. Dry any stubborn leftover solvent
Use full vacuum for 1 hour
6. Auto-Defrost and Drain - this will be a full defrost and drain.
See appendix C for programming details.
Please contact your local Genevac representative for further details on run times, alternatively please e-mail
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com