PROCESSING SAMPLES 19
When fitting sealing caps, the air pressure which may have built up can be
released by lifting the edge of the cap slightly. The caps are manufactured from
a material which is suitable for autoclaving.
When treating samples in any of the test tubes the temperature of the
suspension will rise, especially if the quantities of the material being treated are
small. To avoid this temperature rise, immerse the tube containing the medium
in a beaker containing crushed ice or a suitable cooling mixture. The beaker
can be placed on the adjustable platform and the vessel containing medium
held in the laboratory clamp. However, if the medium being treated is
particularly sensitive to temperature, then one of the cooled treatment vessels
described in sections 3.3, 3.3 and 3.4 should be used.
3.3 Batch Treatment Vessel
This consists of an inner chamber to contain up to 50ml of sample to be
treated, surrounded by a cooling jacket through which a suitable cooling liquid
(e.g. iced water or alcohol) can be circulated.
3.4 Continuous Flow Vessel
This is available for the treatment of even larger volumes where the required
disintegration time is relatively short. This vessel has both inlet and outlet tubes
to the inner chamber which allows the sample to be passed continuously
through at a measured flow rate as disintegration takes place.
Apertures are provided in the back of the ultrasonic cabinet so that the
liquid feed-lines can be passed through to the treatment vessels and
permit sonication with the cabinet door closed.
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