Indeed, I am trying to prepare a standard sample of pure DMT for future TLC identification of it in various plant extractions.

It seems that in chromatography the problem is basically the same. How do I know that in the crude mix there are no substances with similar Rf?

I thought of that setup, but it has a major flaw. It is very difficult to disassemble without shaking off the product from the condenser. On the other hand, I  may try this simple device as proof of the concept before spending money on something more expensive.

P.S. I am looking for a good vacuum pump for my home lab anyway.