Is there a difference between grain derived and synthetic derived ethanol?
Theoretically there is no difference between the two. A molecule of ethanol is the same no matter
how it is produced. However, every production route (natural or synthetic) utilizing different raw
materials (corn sugar or ethylene) and different equipment and processes (age and technology) will
create different impurities in the finished product.
These impurities are found in the parts-per-million range (ppm) and are typically less then 0.002% (20
ppm). In the case of Ethanol if we measure purity to the third decimal place (99.998%) then we can
begin to address the largest contaminants that are found (other contaminants being in the parts-perbillion
range).

In short, the difference between denatured ethanol derived from grain versus that derived
synthetically is non-existent (negligible). The quality of the finished product is really a result of the
purity of the denaturants and the purity of the starting material (ethanol).