AX-R06 — Recovered mass outside label claim tolerance

This is the rule that matters most to anyone buying by the milligram, and it is the one that fires most often.

A vial labelled 10 mg contains a lyophilised cake. That cake is peptide, plus water, plus counter-ion, plus residual solvent and inorganic residue. If the cake weighs 10 mg gross and is 82 % peptide by weight and 98.7 % pure, the vial contains 8.1 mg of the target compound — not 10 mg, and not 9.87 mg either. The arithmetic is set out with a worked example on /methods/peptide-content-vs-purity/ and is implemented in the purity-to-mass calculator.

Most label-claim shortfalls in the index are not fraud. They are the predictable result of declaring a nominal fill mass and saying nothing about water and counter-ion, in a market where nobody asks. But the effect is large: the index's median recovery against label claim is 96.4 %, the 10th percentile is 89.1 %, and gravimetric fill checks show under-fill outnumbering over-fill by roughly three to one.

The tolerance of ±10 % is the index's own and is generous. A pharmacopoeial content uniformity requirement would be considerably tighter.