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Imagine that I defrost a tube of serum (only the yellow stuff, with blood cells removed) standing still and upright in ambient air. I have seen that as it defrosts the sample separates into different bands of compounds. Is the separation that I witness based on a particular compound trait? For example molecule weight? What is this phenomena called? And has it been studied by chemists? I will try to post a photo later if I can get a sample to show you.

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    $\begingroup$ Some of it happens during freezing. Just because the solution you froze was homogeneous (as all solutions should be), it does not mean the solid is homogeneous. As a kid, I discovered that if you suck on a apple juice popsicle, you get the sugar first and the water remains frozen. So the non-water part of the juice was present in cavities of a scaffold of frozen (nearly pure) water. $\endgroup$
    – Karsten
    Mar 20, 2022 at 15:42

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This might be an example of zone separation through the Czochralski technique, if the components were truly dissolved, and the tube was warmed slowly along its access.

However, blood serum, contains proteins, electrolytes, antibodies, antigens, and hormones. Some components, such as lipoproteins, are in a colloidal suspension, rather than dissolved, and can be separated out by ultracentrifugation or, as you have done, by freezing. After freezing has destroyed the colloid, allowing components to clump, they'd segregate according to their densities and other properties, e.g., relative hydrophilic or hydrophobic nature.

You'd need to analyze those bands to see whether you've demonstrated zone refining or breaking a colloid with freezing and then performing gravitational separation.

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  • $\begingroup$ How could I learn about other methods to separate the serum (not necessarily by density?) $\endgroup$
    – Mikkel Rev
    Mar 20, 2022 at 21:03

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