that should work for testing the pump gas before its in your car.
http://www.zeitronix.com/Products/ECA/ECA.shtml
is a good thing to have with e85 or pump gas. you can test the things in the fuel from the tank. and we all know just because you add e85 to a tank doesnt mean it will be e85 when its at the rail.
if the phase seperation occurs your next fill up will be a bit different.