Originally Posted by
peptideguru
99% refers to the purity, and not generally to adulteration.
When you aim for 100%, there will be a few bonds that aren't quite perfect, or will form inert compounds. These are harmless and will be so insignificantly small that they won't make a difference - if you think it's 10,000mcg in an MT2 vial, that would be 100mcg. If you get 20 injections from a vial, that will be 5mcg of impurities per injection.
That's not to say, however, that there will not be any adulterants in the vial - when it's coming from China you don't really have any guarantee.