[rocket_mauled21]

Hi,

I'm working on a lab project using gas chromatography to separate the ethanol out of different grades of gasoline.  Anyway, my lab group and I noticed something strange while we were collecting our data:  It seems like the retention time for ethanol (i.e., the amount of time it takes it to move through the coils in the chromoatograph) depends on the solution it's in:  our standard solution of pure ethanol took longer to move through the chromatograph than the ethanol in various grades of gasoline (we co-injected ethanol and gasoline several times so the gasoline was over 50% ethanol, and the ethanol peak took less time to appear than it did with the pure ethanol solution).  I'm just wondering why this might be?  Would the volatility of ethanol increase in a mixture of nonpolar hydrocarbons like those in gasoline because there are fewer compounds for it to form hydrogen bonds with, or is there some other reason this might happen?