How to read a peptide certificate of analysis (COA)
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A certificate of analysis (COA) is a document from a testing laboratory that records what a specific batch of material is and how pure it measured. For a research peptide it normally reports the batch number, an HPLC purity figure and a mass spectrometry result that confirms identity. This guide explains each part so you can check a COA against the vial in front of you.
What is on a peptide COA?
| Field | What it tells you |
|---|---|
| Compound name | The material that was tested |
| Batch or lot number | Which production batch the result applies to |
| Purity (HPLC) | How much of the peptide material is the target compound |
| Identity (mass spectrometry) | Whether the measured mass matches the expected mass |
| Appearance | What the material looks like, for example a white lyophilised powder |
| Laboratory and date | Who ran the analysis and when |
Why does the batch number matter most?
A COA describes one batch. The first check is always that the batch or lot number on the certificate matches the batch number on the vial label. A certificate for a different batch tells you nothing about the vial you hold.
What does HPLC purity mean?
HPLC (high-performance liquid chromatography) separates the components of a sample and measures how much of each is present. The purity figure is the share of the detected peptide material that is the target compound, expressed as a percentage. A result of 99% means that 99% of the detected peptide signal came from the target peptide and 1% from related impurities.
How does mass spectrometry confirm identity?
Every peptide has an expected molecular mass fixed by its sequence. Mass spectrometry measures the mass of the molecules in the sample, and the result is compared with the expected figure. For example, the expected mass of BPC-157 is approximately 1419.5 g/mol and of MOTS-c approximately 2174.6 g/mol. A measured mass consistent with the expected value supports the identity of the compound.
Purity and identity answer different questions. HPLC says how clean the material is. Mass spectrometry says whether it is the right molecule. A complete COA reports both.
What is the difference between purity and net peptide content?
Purity is the proportion of the peptide material that is the target compound. Net peptide content is the proportion of the total powder weight that is peptide at all. Lyophilised peptides also contain counter-ions from the salt form, such as acetate, and a small amount of residual water. A material can therefore have a high purity and a net peptide content below 100%. The two figures are not interchangeable.
What are the warning signs on a COA?
- No batch number, or one that does not match the vial.
- A purity figure with no method stated.
- No identity result.
- No named laboratory or date of analysis.
- A certificate that names a different compound, salt form or quantity from the listing.
Where are Ascend Research COAs published?
Batch documents are published on the COAs page. Our page on understanding research-material documentation explains what the documents do and do not establish, and our storage guide covers keeping the COA with your batch record.
Frequently asked questions
What is a certificate of analysis for a peptide?
It is a laboratory document for a specific batch that records the compound tested, its measured purity, an identity result and the date and laboratory of analysis.
What does HPLC purity mean on a peptide COA?
It is the percentage of the detected peptide material that is the target compound, as measured by high-performance liquid chromatography.
How does mass spectrometry confirm a peptide's identity?
It measures the molecular mass of the sample. A measured mass consistent with the expected mass for the sequence supports the identity of the compound.
Is purity the same as net peptide content?
No. Purity is the share of peptide material that is the target compound. Net peptide content is the share of the total powder weight that is peptide, the remainder being counter-ions and residual water.
How do I match a COA to a vial?
Compare the batch or lot number on the certificate with the batch number printed on the vial label. They should be identical.
All Ascend Research products are sold strictly for laboratory research use only. They are not for human or animal use, and nothing in this article is medical advice.
The Ascend Research team