AX-R07 — Declared gravimetric mass balance does not close
Declared water, counter-ion, peptide content and residual do not account for 100 % of the mass.
The predicate
Published literally. A rule you cannot read is an accusation you cannot check.
coa.water != null && coa.counterIon != null && coa.peptideContent != null && abs(coa.water + coa.counterIon + coa.peptideContent + coa.residual - 100) > 1.0
Why this rule exists
Everything in the vial weighs something. Water, counter-ion, peptide, residual solvent and inorganic residue are exhaustive and mutually exclusive categories, and they must sum to the mass of the cake.
When a certificate declares 4.0 % water, 3.5 % acetate and 98.0 % peptide content, it has declared 105.5 % of the vial. One of those three numbers is wrong, or one of them is being reported on a different basis — most commonly, peptide content reported on an anhydrous, salt-free basis while water and counter-ion are reported as-is. That is a legitimate convention and it is why the rule allows 1.0 pp of slack and why the index's own records state the basis explicitly on every content figure.
Beyond 1.0 pp the certificate is not reconcilable without additional information that the certificate does not supply.
The index publishes its own mass balance on every record where the four measurements exist, closed to within 0.02 pp by construction, precisely so that a reader has something to compare a supplier's declaration against.
Incidence
How often the rule fires, where, and when. A rule that never fires is not calibrated; a rule that fires on half the index is measuring the population rather than screening it.
| Supplier | Flagged | Records in index | Rate | |
|---|---|---|---|---|
| GGPeps | 13 | 371 | 3.5% | |
| QSC | 13 | 350 | 3.7% | |
| SIG | 12 | 160 | 7.5% | |
| GSP | 12 | 180 | 6.7% | |
| TFC | 11 | 417 | 2.6% | |
| Homopeptide | 10 | 457 | 2.2% | |
| ASY | 9 | 190 | 4.7% | |
| WXT | 8 | 301 | 2.7% | |
| JEEP | 8 | 230 | 3.5% | |
| ERP | 7 | 205 | 3.4% | |
| WWB | 4 | 398 | 1.0% | |
| CPC | 3 | 227 | 1.3% | |
| HJ | 3 | 247 | 1.2% | |
| SinoPep | 1 | 162 | 0.6% | |
| FGP | 1 | 200 | 0.5% |
Flagged records per quarter
2024-Q1: 0 · 2024-Q2: 0 · 2024-Q3: 2 · 2024-Q4: 5 · 2025-Q1: 0 · 2025-Q2: 3 · 2025-Q3: 26 · 2025-Q4: 28 · 2026-Q1: 11 · 2026-Q2: 37 · 2026-Q3: 3