All sorts of chemicals are added to ethanol to denature it. You can see in the Code of Federal Register all the approved formulas for doing that:
From methanol to gasoline to pyridine are used - and you generally can't tell what you have when you get denatured alcohol. If the label says "SD alcohol XX" where XX is a number, you can look up in the CFR link above to find out which additives were used.

On the chlorophyll, it sounds like they use the soaking method for sensitizing to minimze the degradation of the chlorophyll.