MSE Soniprep 150 Plus - Processing Samples with Soniprep; Sample Vessel Selection; Basic Processing Techniques

PROCESSING SAMPLES 18
3. PROCESSING SAMPLES
3.1 Vessels for Samples
NOTE:
Minimum Volume - Volumes of less than 1ml may be treated with the
exponential microprobe. The sample should be held in a micro tube.
Maximum Volume - A maximum of 100ml may be treated at any one time.
However, larger volumes may be processed by using the treatment vessels. It
is preferable to use a narrow vessel rather than a wide one. Twice the volume
in a narrow vessel takes a shorter time to process than the same volume in a
wider vessel. Twice the volume or concentration takes twice as long to process.
Materials that are particularly resistant to ultrasonic energy, however, should be
processed in the smallest area practicable. Since the energy radiates from the
probe tip in the shape of a cone, the more confined the sample under the tip
the better the results. A narrow, relatively short test tube is also called for when
processing small quantities, say of the order of 4ml. The probe tip should
displace as much liquid as possible to force a long liquid height or ‘head’ above
the vibrating tip. This prevents foaming or whipping the solution out of the test
tube. A wide beaker is not normally suitable.
There is considerable evidence that the shape of the container has great
influence on the rate of release of soluble protein or the efficiency of the cellular
breakage. This is probably more the function of mixing than anything else, since
the individual components are not directly exposed to the action of the probe tip
for more than a second or two. If the volume is very large, then individual cells
are not in the area of cavitation activity for a sufficient period of time. The probe
tip should be below the surface of the liquid by approximately 13mm (1/2’) and
should not be too far from the bottom of the vessel l(again approximately
13mm). If the tip is not satisfactorily immersed, a considerable quantity of air
may be trapped in the solution thus dissipating the power delivered and not
allowing it to be transmitted to the solution. As there is sufficient force
generated by the Soniprep 150 Plus to fracture or shatter glass, the probe tip
must not be allowed to come in contact with, or come close to, the bottom of
the vessel.
3.2 Basic Processing
Test tubes of 20ml and 100ml nominal capacity are available for certain
applications. In addition to these, cooled treatment vessels are available for use
when it is important that the media being treated should be subjected to
minimal temperature rise.
A range of rubber sealing caps are available for all tubes and cooled treatment
vessels. The probe is inserted through the sealing cap which fits over the mouth
of the vessel, or tube, and provides an air tight seal.
For ease of manipulation and to effect the best possible seal, the edge of the
hole in the sealing cap should be lightly smeared with silicone grease. When
using sealing caps, ensure the tube is securely clamped to prevent downward
movement of the tube and consequent disengagement from the probe.