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QUI-1057
Page 56
Markes International Ltd
T:
+44 (0)1443 230935
F:
+44 (0)1443 231531
E:
www.markes.com
First insert a 2-5 mm plug of quartz or glass wool using a suitable flexible tool such as a 15 cm length of
1/16 -inch, narrow bore plastic tubing (PTFE or PEEK tubing is ideal.)
Pour in the required amount of sorbent. Analytes enter and desorb from the trap through the restricted
end. Multibed traps must therefore be packed with the sorbents arranged in order of increasing strength
from the narrow end. 1 to 3 mm plugs of quartz wool must separate different sorbents.
Plug the end of the trap with another glass wool plug, backed with a packing retaining spring.
If unsilanised glass (rather than quartz) wool is used in the cold trap, it may cause degradation and / or
tailing of polar and labile compounds. Silanised glass wool does not suffer from these limitations but
must not be taken above 275 °C or breakdown products from the silylating reagent will coat the sample
flow path of the desorber, reducing recovery of high boiling compounds.
NOTE
: A 6 cm length of the wider bore section of the trap tube, measured from the point of the bore
restriction, is subjected to full cooling and heating power. The trap packing, including all but the
back glass / quartz wool plug, should be within this 6 cm length of the trap
NOTE
: Do not over-compress the cold trap packing as this will cause high impedance, which may limit
trap desorption flows.
If high trap desorption flows will be required, for example when using a high split ratio, use 40-60 rather
than 60-80 mesh sorbent.
5.3.2
Removing / replacing a cold trap
The carrier gas supply and
compressed air to the
instrument and the instrument itself
must be turned off before starting.
See video tutorials for animated cold trap removal