I need to measure and transfer 10 ml of a fairly dilute suspension at a time to another container.

But no matter how diligently I do it, sedimentation happens quickly after mixing and successive transfers have different strengths or concentrations of solute.

Is there a way to achieve this without increasing the viscosity of solvent?

Note: I have to start with a dilute suspension and then transfer measured quantities of it. I have no other option.

  • $\begingroup$ Maybe separate the suspension into its components and transfer separately? $\endgroup$ – Zhe Oct 15 '18 at 17:40
  • $\begingroup$ Is it the sedimentation of the stock solution that is the problem, or the sedimentation of a diluted solution that is the problem? $\endgroup$ – MaxW Oct 15 '18 at 17:51

Stir the dilute suspension rapidly, e.g., using a magnetic stirrer. Let a vortex be generated whose size you can use as an estimate for vigor of stirring. With the same mixing vigor, and using the same size vessel and same original volume for the suspension, and withdrawing only a small portion (say, ~10%) for the other container(s) should enable fairly repeatable measurements.

For obsessive accuracy, you could do three withdrawals: #1 for reference, #2 for experiment, and #3 for reference. If #1 and #3 show the same concentration of solid, #2 will certainly be the same, and the concentration will be verified while sedimentation will be proven to be absent.


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