DEMO=0 python3 build.py after wiring real content.Three different numbers get called purity. Only one of them tells you what you think it does.
The HPLC number. 99% of the UV-absorbing material is the main peak. It says nothing about mass, identity or water content.
Purity is about the proportion of the vial that is your compound rather than something else. Content is how much of it there is in absolute terms. A 99% pure vial that contains 6 mg instead of 10 mg is a 99% pure underfill.
A 10 mg peptide vial often contains considerably more than 10 mg of powder because of counter-ions, water and bulking agents. Net peptide content is the only figure comparable to what you paid for.
Purity percentage, net content in mg, and the chromatogram. If a vendor cannot supply all three, the number they are quoting is marketing.