This article is for laboratory and research information only.
A Certificate of Analysis (CoA) is the single most useful document when sourcing research peptides. It tells you what is actually in the vial. It's only useful if you know how to read it, though, so here is what each section means and what red flags to look for.
What is a Certificate of Analysis?
A CoA is a report from an analytical laboratory that tested a specific batch of a compound. For peptides it normally confirms two things: identity (is this the right molecule?) and purity (how much of the sample is that molecule?).
The key sections of a peptide CoA
1. Product and batch details
Look for the compound name, batch or lot number, test date and the name of the testing laboratory. The batch number should match the label on your vial. A CoA with no batch number, or one that never changes between orders, tells you very little.
2. HPLC purity
High-Performance Liquid Chromatography (HPLC) separates the components of a sample. The result is shown as a chromatogram, a graph with peaks. The main peak is the target peptide, and purity is the main peak's area as a percentage of the total.
- 98–99%+ is the standard to look for in research-grade peptides.
- The chromatogram itself should be shown, not just a number.
- Small extra peaks represent impurities such as truncated sequences or synthesis by-products.
3. Mass spectrometry (MS)
Mass spectrometry confirms identity by measuring the molecular weight. The observed mass should match the theoretical mass of the peptide. For example, BPC-157 has a molecular weight of around 1419.5 g/mol. HPLC tells you how pure something is, while MS tells you what it is. A good CoA includes both.
4. Appearance and other tests
Many CoAs also note appearance (for example, a white lyophilised powder, or blue for GHK-Cu), solubility, water content, or endotoxin testing. These are useful extras.
Red flags
- No batch or lot number, or a number that doesn't match the vial.
- A purity figure with no chromatogram.
- No mass spectrometry or identity test.
- No named testing laboratory, or only in-house testing.
- The same CoA image used for several different products or batches.
In-house vs third-party testing
In-house testing is carried out by the manufacturer or seller. Third-party testing is done by an independent lab with no stake in the result, which makes it more trustworthy. At Aura Lab Peptides, CoA results are shown in the product images. Examples include our BPC-157 10mg, TB-500 10mg and NAD+ 500mg.
FAQ
Is 99% purity always better than 98%?
Generally yes, but a 98% result with a clean chromatogram and confirmed mass from an independent lab is worth more than an unverified 99.9% claim.
Does purity change after delivery?
It can, if the peptide is stored badly. Heat, moisture, light and repeated freeze-thaw cycles all degrade peptides over time. See our storage guide.