Potentially plasticizers depending on concentration, yes. But you could anyways pre-emptively clean it well so as to prevent any such problems. Check this for more info:
https://www.dmt-nexus.me...aspx?g=posts&t=26324TLC wont work for sodium hydroxide/sodiumacetate/carbonate etc though . But that's easy enough to check for if in significant quantities . For example, if you heat up some of your product, alkaloids will generally melt and vaporize quite quickly, while none of those bases/salts will melt at lighter temperatures. Also if you wash your product with water it should remove any of those too (only wash non water-soluble freebase substances though)
As for solvent, TLC will generally not work for that, but again, you can always use clean solvents in the first place and for example redissolve with acetone or ethanol or some other less toxic clean evapping solvent and let it dry again, which will help removing any traces of other solvents you used before.
TLC will be more appropriate for testing for other alkaloids/active products (for example testing new plants looking for tryptamines of interest), or if you want to confirm the identity of a substance, or if you want to know what are the substances in a mixture (and possibly their relative concentration )