https://www.thevespiary.org/rhodium/Rhodium/chemistry/equipment/dryingagent.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/equipment/dryingagent.html)
zinc chloride is not suitable for drying amines. This is due to complex formation, so the same should apply to zinc sulfate. The document says nothing about incompatibilities of copper sulfate but I recall it was also unsuitable for drying amines, and as it also forms complexes with them it sounds reasonable as well.http://www.chemistry.ccsu.edu/glagovich/teaching/472/qualanal/tests/copper.html (http://www.chemistry.ccsu.edu/glagovich/teaching/472/qualanal/tests/copper.html)
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