I am trying to purify starch from a sample pulled from the dirt. It is impossible to clean the sand from every inch of the sample, and after purifying, I've noticed my starch, which should be on the bottom of my centrifuge tube, is accompanied by a significant amount of sand.
I am hoping to find a separation solution that will keep the sand grains at the bottom, and allow my starch granules to float after being spun in a centrifuge. Does anyone know of something I could try?
I cannot use filters, as the amount of starch present is so small, I will lose all of my product to the paper.
Good day, Chloe Cowen! Hope you are doing well.
I suppose you should try to dissolve your starch, remove sand by centrifuging and precipitate starch. Solvents for starch are 90% aqueous DMSO, DMSO with little LiCl, DMF with LiCl, some ionic liquids or alkali solutions. Please, check the following discussions:
https://www.researchgate.net/post/Whats-the-best-solvent-to-dissolve-starch-Any-success-in-dissolving-it
https://www.researchgate.net/post/Is_starch_can_dissolve_in_chloroform
https://www.researchgate.net/post/What-is-the-solvent-that-dissolve-starch-without-using-water
Best of luck in your research!
Yours sincerely,
M. Sc. Vadym Chibrikov
Department of Microstructure and Mechanics of Biomaterials
Institute of Agrophysics, Polish Academy of Sciences
I propose wet sieving or unassisted sedimentation (gravity settling). For details, see the attached file.
You could perhaps use a centrifuge. The starch would settle to the bottom of the tube while the sand stays suspended in the liquid, which would then be carefully poured.
Hope this helps!
The centrifuge technique proposed by Mohammed Al-Saady is certainly an option but in fact it works the other way round. Because the densities of starch and sand are typically 2500 and 1500 kg/m3 respectively, and their particle sizes are > 500 and < 100 micrometers respectively, it is the sand that settles with the starch remaining in suspension. [Provided that very low g forces are applied because starch also has a higher density than water, so also starch has a tendency to settle. That is why I prefer sieving or unassisted gravity settling. In fact you can calculate all possible scenarios from Stokes Law by applying known values for density, particle size, and applied g force (see the attachment in my earlier comment].
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