ASTM D2700 8.3.1 Isooctane (2,2,4-trimethylpentane) shall be no less than 99.75 % by volume pure, contain no more than 0.10 % by volume n-heptane, and contain no more than 0.5 mg/L (0.002 g/U.S. gal) of lead.11
It is used as the standard in determining the octane numbersof fuels (its antiknock octane number is 100)
