A Certificate of Analysis is the document that tells you what is actually in the vial. A COA that is generic, undated, or reused tells you nothing. This is how to read a real one and what each field means.
What a COA is
A COA is a lot-specific analytical report for one production batch. The key word is lot-specific. A COA that is not tied to the exact batch you received cannot describe your material, because purity varies between batches.
The fields that matter
- **Product identity and lot number.** Names the compound and the specific batch. No lot number is a red
flag.
- **Test date.** Recent, and tied to the batch. An old or missing date is a red flag.
- **Purity, by HPLC.** A percentage, typically 98 to 99 percent or higher for research-grade material.
This is the fraction of the sample that is the target peptide rather than impurities.
- **Identity, by mass spectrometry.** Confirms the measured molecular weight matches the expected peptide.
Purity without an identity check is only half the picture.
- **Analytical methods and laboratory identity.** The COA should name the methods used (HPLC, MS) and the
lab that ran them. An independent third-party lab carries more weight than an unnamed in-house claim.
How to use it before you work
Check the labeled mass on the COA against the vial before calculating any reconstitution volume, since the COA reflects the actual measured content of that batch. Read any batch-specific stability or solubility notes before you design a protocol.
Red flags in one list
- No lot number, or a lot number that does not match the vial.
- No test date, or a date that never changes across orders.
- The same COA reused for every batch.
- No analytical method named, or no identifiable testing lab.
- Purity stated with no supporting chromatogram or method.
A supplier that publishes clean, lot-specific, third-party COAs is telling you something real about how they operate.
For laboratory research use only. Not for human consumption.