How to read a peptide COA
Research context reviewed 5 October 2026See “99% purity” on a listing? Do not stop there. That figure only makes sense when you know which sample was tested, by what method, and whether the document connects to the material you are comparing.
Use these five checks on the original PDF, not a cropped screenshot.
1. Which sample does it describe?
Find the product name, sample or batch number, issuer and test date. A report for one batch does not automatically cover another. If the vial or order record has no matching reference, ask the seller which report applies.
2. Was the molecule identified?
Mass spectrometry measures molecular mass and can compare it with the expected molecule. A high purity figure without an identity result does not tell you what made the main peak.
3. What does the purity figure measure?
HPLC is a method that separates detectable components. A result such as 99% HPLC purity usually means the main detected peak made up 99% of the detected peak area under that method. It does not mean that 99% of the vial's powder is peptide, or that the vial contains the labelled milligrams.
4. What is missing?
Identity and HPLC purity do not establish sterility, endotoxin level, water content, residual solvents or net peptide amount. Those require their own tests. If a result is absent, do not fill it in from the headline percentage.
5. Who issued it, and what is its status?
A supplier-issued COA and an independent laboratory report are different sources of evidence. A file labelled reference template is not, by that label alone, a batch-specific result for the vial you select. Read the entire document, including the last page.
A hypothetical example: say you are comparing a BPC-157 10 mg listing and see “99% HPLC purity” in a document. That number does not establish 10 mg per vial, identify the peptide on its own, or show that the report belongs to the vial being offered. Look for those details separately; do not infer them from 99%.
For a multi-peptide blend: check whether the document describes the finished mixture or separate ingredients. Ask whether the method can distinguish each named peptide in that mixture. One overall purity percentage does not, by itself, verify every ingredient or its labelled amount. KLOW's four-component listing is one example of where that question matters.
The buying decision: open the document linked from the exact PEPTALIAS product listing you are considering. Match its sample and result to your selected material. If the link is not clear, ask PEPTALIAS before ordering.
PEPTALIAS material is for laboratory research only, not human or veterinary use.
Sources: International Council for Harmonisation, Q2(R2) Validation of Analytical Procedures (2023).