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XL Usermanual-Rev A5.docx
In the third step, water that is strongly bound to the solids of the sample
(called sobbed water) is converted to vapour and removed from the product,
this process being referred to as de-sorption. Removing moisture in the de-
sorption phase or secondary drying phase, is done at a higher product
temperature and at the lowest possible pressure
8.1
Hints; Tips & Reminders
The selection of the appropriate sample container is important to ensure
samples are dried efficiently. Freeze drying emanates from the surface area of
the sample, so the larger the surface area in respect to its depth/thickness is a
determining factor in the speed of the drying cycle. “Never let the depth of
sample exceeds its diameter” especially in vials, flasks trays etc.
Maintain the vacuum pump regularly, oil changes must be made as per
manufacturer’s instructions. Poor vacuum performance could mean
contaminated oil.
Ensure all seals and surfaces are clean and properly seated to avoid vacuum
leaks.
Always start the freeze dryer and the vacuum pump 30-40minutes before use.
Keep the freeze dryer operational if you expect to use it more than once during
the day.
Bibliography
8.2 Articles, Books & Research papers on Freeze drying.
It should be noted that many of the earlier publications, books etc. are concerned
with the freeze drying of foods, this emphasis arose primarily because Freeze drying
was considered to be the major application for this technique. This has been borne
out by how the major food companies, world-wide, have continued to use this
process of preservation. However, today freeze drying has many applications not
least of which is in the production of pharmaceutics, biological active materials and
countless others from archaeology to human tissues.
Today many papers and articles on Freeze Drying are available via the internet and
the various search engines therein, Google etc. and by entering such titles as “Freeze
Drying research methodologies” etc. papers are available instantly.
Another source of information is via the publication “Drying Technology”, published
by Taylor & Francis,
Here is list of books & papers that may assist you in your work:
Books.
An Introduction to Freeze Drying by James M.Flink& Henning Knudsen (ISBN 87-872-
0084-8)1983
Freeze Drying of Food Products by J.C.Harper& A.L.Tappel- Advances in Food
Research Vol.7 Academic Press 1957.