How does a freeze-thaw cycle separate a mixture?

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.




This *might* be an example of [zone separation through the Czochralski technique](https://en.wikipedia.org/wiki/Czochralski_method), 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](https://en.wikipedia.org/wiki/Colloid), rather than dissolved, and can be separated out by [ultracentrifugation](https://pubmed.ncbi.nlm.nih.gov/7811751/) or, as you have done, by freezing. After freezing has destroyed the colloid, allowing components to clump, they'd [segregate](https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/abs/freezing-colloidal-suspensions-periodic-ice-lenses-and-compaction/1571B7EC27E859FB67DAF6E2F88C1A4F) 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.


 1