I'm not an expert, nor do I give half a damn about chemistry, (or biology for that matter) but the pH scale stops at 0.

It's measured on the concentration of hydrogen ions in relation to distilled water. If something were to have a -1 rating, it would have to have 100,000,000 times the concentration of distilled water.

To round my statement out, I'm guessing that there is more than one part hydrogen ion per hundred million parts of distilled water. Thus, the substance that has a pH of -1 would have to be composed of MORE than 100% hydrogen ions.

What is it they say about silence being golden?