Chemistry - How to test for methanol?

Solution 1:

Sorry @ JavaScriptCoder, but I've to agree with aventurin. I'd say idoform test should have been done in a certified laboratory because of safety concern. However, I think fractional distillation might be helpful for this identification (or simply verification). OP can do this at home since he/she has done simple distillation at home. Ethanol/water binary system give an azeotrope, which boils at $\pu{78.1 ^\circ C}$ and gives $95\%$ ethanol. Methanol, on the other hand, make no azeotrope with water, and boils at $\pu{64.7 ^\circ C}$. The temperature range of $\pu{13.4 ^\circ C}$ need only about ≤20 theoretical plates to separate. If you get first distillate below, say, $\pu{67 ^\circ C}$, then you got methanol or something other than ethanol. So, don't drink it.

For more information, read the Wikipedia page having Azeotrope tables.

Solution 2:

There's probably no reliable chemical test for the presence of methanol in alcohol mixtures that could be carried out at home without decent laboratory equipment.

Qualitative tests such as esterification with boric acid and subsequent flame test or oxidation to formaldehyde and its detection are unreliable, especially in the presence of ethanol. I advise against using such tests to decide about the presence of methanol in distilled liquors.