A quick search on the 'net came up with this device
http://www.digatronusa.com/pricing-fuel-tester.shtml
For an organization to test for fuel, they need base line samples of known virgin fuel. Our organization went so far as to have a list of fuels that we are allowed to use because each fuel has a different color, and one of the tests is to check for color.
For more specific information I'd suggest talking to any of the Racing fuel manufactures.