Genevac HT-8 & HT-12 Series II Evaporating Systems
Page 40 of
64
04-4541
Issue 1-9 – June 2008
Condensation
TFA Creep
6.2 Problem
prevention
Condensation of the evaporating solvent will occur
when the solvent vapour temperature is above that
of the chamber walls.
This is most likely to occur with commonly used
solvents such as NMP, DMI, DMSO and possibly
DMF.
To prevent this, it will be necessary to pre-heat the
chamber.
To do this, remove the sample holders and set the
Minimum Chamber Temperature field to 40 degrees
on the
Run Data
screen and start the run.
The chamber will take approximately 20 minutes to
reach this temperature.
Note that the Coolheat lamps will not operate during
this pre-heating cycle.
If condensation occurs unexpectedly, immediately
switch off the lamps by entering 0 into the Heat of
Elapsed Time field on the
Run Data
screen.
Pre-heating the chamber is not recommended when
evaporating volatile solvents such as TFA,
acetonitrile or methanol.
TFA exhibits the property of ‘creeping’ which, is the
movement of the TFA in liquid phase up the inside of
the tubes, vials or microtitre plates.
Problems can arise if solvent containing product is
deposited in this way on the top face of plates.
During rotation of the rotor, solvent and product are
thrown onto the Quartz glass windows in front of the
lamps.
Whilst the solvent evaporates, the product becomes
carbonised by the heat from the lamps and form
sites for crack propagation to take place.
Inspect glasses at regular intervals and clean with a
lint free cloth and acetone.
If the contamination becomes excessive and
carbonised as shown, contact Genevac Service.
Genevac manufacture a range of specialised sample
holders to protect the Quartz lenses. Call Genevac
Sales for details.
Bumping and spitting is unpredictable and may occur
with any solvent or mixture.
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