Hello,
i'm having a hard time to redisperse silica after centrifugation at 15 000 g for 10 minutes. i'm using a probe type sonicator but would like to avoid it, as it causes black sediments to form (presumably the metal from the Probe sonicator). Putting the probe into a beaker with water next to the tube does not help in redispersion, even at full power and in pulse mode for 10 minutes, but I would like to avoid putting the sample in direct contact with the probe sonicator. How do you all approach it?
Thanks.
If redispersion is not possible with a bath sonicator, then the particles aggregated once they became closer to each other upon centrifugation. They are not stable enough or you are centrifuging for more time than necessary.
Hi, the standard procedure is the sonicator in direct contact with the medium. Nevertheless, there are a few tricks to try:
1) Check the probe corrosion. If you see circles or wrinkles on its bottom side, replace it with a new one. These things go off pretty fast due to cavitation.
2) Try a different probe better suited to the dispersion volume of your beaker.
3) Adjust the pulse duration (on/off period) and the power amplitude.
4) Cool down the medium to prevent overheating, e.g., put ice around your beaker.
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