[tcurl]

I am looking for a dye very soluble in ethanol but not soluble, or minimally soluble, in water or gasoline. The colour of the resultant dyed ethanol is not important as long as it is easily distinguishable as coloured

[KritikalMass]

http://www.ihcworld.com/_technical_tips/solubility_chart.htm

[tcurl]

Thanks for the link to the chart. I'd already gone that route. The problem looks simple, but I'm guessing there is not a well known solution. I am trying to find an inexpensive way to detect ethanol adulteration of automobile fuel. Clearly the dye, needs to "fall through" pure gasoline, and gasoline which may have a small amount of absorbed water. If there is ethanol in the gasoline it will absorb the dye changing the color of the entire mixture.

[Borek]

If ethanol is dissolved is gasoline it won't necesarilly dissolve the dye the way you want it to. IMHO you should rather look for some simple reaction of ethanol.

[DrCMS]

Thanks for the link to the chart. I'd already gone that route. The problem looks simple, but I'm guessing there is not a well known solution. I am trying to find an inexpensive way to detect ethanol adulteration of automobile fuel. Clearly the dye, needs to "fall through" pure gasoline, and gasoline which may have a small amount of absorbed water. If there is ethanol in the gasoline it will absorb the dye changing the color of the entire mixture.

No the problem is not simple at all and your understanding of how dye solubility works is plain wrong.