How to read a peptide certificate of analysis
A COA is only useful if you can read it. Here is what each line on a NOVA Q certificate means, and what its absence on someone else’s certificate should tell you.
A certificate of analysis is the independent lab’s report on a specific production lot. It is the difference between a number printed on a label and a result you can trace. Every field exists to answer one question: is this the compound it claims to be, and is it clean?
The annotated certificate
● PASS| Test | Method | Spec | Result |
|---|---|---|---|
| Identity | HPLC-MS | Conforms | Confirmed |
| Purity | HPLC | ≥ 99.0% | 99.4% |
| Net peptide content | HPLC / N | Report | 82.4% |
| Endotoxin | LAL | < 1.0 EU/mg | < 0.5 EU/mg |
| Heavy metals | ICP-MS | < limits | ND |
Identity — is it the right molecule?
Identity is confirmed by high-performance liquid chromatography paired with mass spectrometry. HPLC separates the sample by how its components move through a column; MS confirms the exact mass. Together they establish that the material matches the claimed compound and not a look-alike. A certificate that reports purity but never confirms identity has skipped the first question.
Purity — how much of the peptide is the target peptide?
Purity, measured by HPLC, is the share of the peptide present that is the intended sequence, separated from truncated or deleted chains produced during synthesis. Research grade is 99% or higher. This is the number most suppliers lead with, and often the only one they show.
Net peptide content — the number most sellers omit
Net peptide content answers a different question: of the total mass in the vial, how much is actually peptide, versus water, salts and counter-ions left from synthesis. A vial can be 99% pure and still be well under 100% peptide by mass. When a certificate reports purity but not net peptide content, you cannot know how much material you are actually holding.
Endotoxin and heavy metals — the contaminant screens
Endotoxin is screened by the LAL assay and reported in EU/mg; a clean synthesis handled properly reads low. Heavy-metal screening by ICP-MS looks for arsenic, cadmium, lead and mercury, with “ND” meaning not detected at the method’s limit. These screens are frequently left off entirely. Their absence is not a pass; it is a blank.
Rule of thumb: a certificate should name the lab, name the lot, and report identity, purity, net peptide content, and contaminant screens. If any of those is missing, treat the number that remains with suspicion.
Shared versus lot-specific
The most common shortcut in the category is a single representative certificate shown for an entire product, rather than the report for the batch you receive. A representative COA tells you what a good lot once looked like. A lot-specific COA, tied by QR to the vial in your hand, tells you about your material. NOVA Q publishes the latter. You can pull it yourself at Verify a Lot.