[fuzzfactor]

Naphtha is a bulk petroleum hydrocarbon commodity found in numerous grades.

It is a major highly flammable component of gasoline but has low octane rating on its own. So to make it into gasoline they boost it with major percentages of high-octane blendstocks and ethanol plus detergent packages and additives for motor fuel use. This is the type of naphtha where things like the benzene and sulfur content are present but not in excess of the agreed amount. For fuel use the color of the material does not need to be as water-white as it does for paint.

Naphtha itself is supposed to be a clear distilled petroleum product that evaporates without residue and there are grades for use as paint thinner having various evaporation rates to choose from. For decades in places there have been restrictions on things like benzene in paint materials so there are naphtha grades certified to meet these requirements, unlike for fuels benzene is usually then certified as being absent, and "odorless" varieties will have little to no sulfur.

The barbecue fluids, which are mostly slower-evaporating, I wouldn't think would be recommended.

Regardless, any (potentially undesirable) thing the solvent picks up on its way to the test tube or evaporation dish will end up in the residue at its final stage.

Alkaloids OTOH would not be such a short message . . .