I'm a protein scientist for a large biotech company. I can vouch that most products on inserts range from 90% to 99% for a quality product. Contaminants like truncation, post translational modifications, and other proteins that are unresolveable during the chromatography portion of production make up for those differences. HPLC results like this can be further supported by SDS-PAGE and densitomitry if concerned. Sadly, there's no way to know what contaminants are present without mass spec, peptide sequencing, etc. There's also no way to confirm that the GH is in a bioactive confirmation and theres only one form of the protein without light scattering analytical techniques. I can confirm that I started 4 IU/day about 3+ weeks ago from QS and already can tell the benefits without question after 1 kit.