A Certificate of Analysis (COA) is the lab report behind a research compound. It tells you what was tested, how it was tested and what the results were. Knowing how to read one takes a few minutes, and it is the single best way to judge whether a supplier’s quality claims hold up.
This guide walks through each section of a typical peptide COA, using the layout of the independent HPLC-UV reports we publish for Atlas Amino products.
1. Report details
The top of a COA identifies the report itself: a report number, the date it was generated, and often a verification ID. These let you confirm the document is genuine and match it to the product you are buying. A COA with no report number or no testing lab named is a warning sign.
2. Sample identification
This section records which compound was tested, who requested the test, and the key dates: when the sample was requested, received, tested and reported. Check two things here:
- The compound and strength match the product. A report for a 20 mg vial tells you about that strength, not automatically about a 10 mg vial of the same compound.
- The dates are recent enough to be relevant to the stock being sold.
Some reports also list a lot or batch number. When a lot number is present, it ties the results to a specific production run.
3. Purity (HPLC)
Purity is usually measured by high-performance liquid chromatography (HPLC). The sample is separated into its components, and a detector measures each one. Purity is the main peak’s share of everything detected, expressed as a percentage.
For research peptides, results of 98% and above are generally considered high purity. Our published reports, for example, range from 98.57% to 99.96%.
4. Content and fill accuracy
Purity tells you what share of the material is the target peptide. Content tells you how much material is actually in the vial. A good COA lists both the expected amount and the measured mass, plus the fill accuracy as a percentage of the label claim.
| Field | What it means |
|---|---|
| Expected content | The amount stated on the label, for example 10.00 mg |
| Measured mass | The amount the lab actually found in the vial |
| Fill accuracy | Measured mass divided by expected content |
A result slightly above 100% is common, because vials are often filled with a small overage. A result well below 100% means the vial holds less than the label states.
5. The chromatogram
Most HPLC reports include a chart called a chromatogram. The x-axis is time and the y-axis is detector response. A single tall, sharp peak with little else around it indicates a clean sample. Several sizeable secondary peaks suggest impurities or degradation.
6. Appearance
Lyophilized peptides are usually recorded as a white powder. Some compounds have a characteristic color, such as GHK-Cu, which is blue because of its bound copper. If the appearance in the report doesn’t match what arrives, ask the supplier about it.
Quick checklist
- A named, independent testing laboratory
- A report number you can match to the product
- The same compound and strength as the product you are buying
- An HPLC purity result, ideally 98% or higher
- Measured content close to the label amount
- A recent test date
You can review every Atlas Amino report on our Certificates of Analysis page, and each product page summarizes its report’s key numbers.