What is a COA?
A Certificate of Analysis (COA) is a lab-issued document that verifies the identity, purity, and quality of a specific production lot. Lab COA PDFs are published per product where available in our COA library; others on request.
A proper COA includes at minimum:
- Lot number - unique identifier for the production batch
- Peptide name and sequence - confirms what was synthesized
- HPLC purity data - chromatogram with purity percentage
- Mass spectrometry data - confirms molecular weight/identity
- Residual solvent analysis - ensures safe handling for research
- Endotoxin testing - critical for cell culture work
- Test date and lab name - traceability and accountability
HPLC: the purity fingerprint
High-Performance Liquid Chromatography (HPLC) is the gold standard for peptide purity analysis. The instrument separates compounds in a sample based on their chemical properties, producing a chromatogram - a graph with peaks at specific retention times.
Here is what to look for in the HPLC section of a COA:
The main peak
The chromatogram typically shows a dominant peak at a specific retention time for the target peptide. The area under the peak (as a percentage) is the reported HPLC purity. Target thresholds depend on the intended analytical application and the laboratory’s own specification — there is no single site-invented cutoff.
Impurity peaks
Smaller peaks at different retention times indicate impurities - typically truncated sequences, deletion sequences, or residual protecting groups from synthesis. These can appear in small amounts; acceptable impurity profiles depend on method and lab specification.
Retention time
The retention time should match the reference standard for the specific peptide. A shift in retention time can indicate a wrong sequence or a modified product.
Mass spectrometry: identity confirmation
While HPLC tells you purity, mass spectrometry (MS) tells you identity. The instrument measures the molecular weight of the compound, which must match the theoretical molecular weight of the peptide.
For example, if you order BPC-157 (theoretical MW ~1419.5 Da), the MS data should show a peak at or very near this molecular weight. A significant deviation means you have the wrong compound - even if the HPLC purity is 99%.
Why both tests matter
A peptide can be 99% pure (HPLC) but still be the wrong peptide (MS). HPLC alone confirms purity but not identity. Mass spec alone confirms identity but not purity. You need both to be confident in what is in the vial.
Reading the purity number
| HPLC Purity | Grade | Use case |
|---|---|---|
| 99%+ | Often specified for sensitive work | Cell culture, in-vitro studies, sensitive assays — when the lab’s method calls for it |
| 98–99% | Common catalog target | Many analytical and standard lab protocols |
| 95–98% | May fit screening use | Acceptable only if the laboratory specification allows it |
| Below 95% | Check the lab spec | Purity requirements depend on the intended analytical application and laboratory specification |
Residual solvents and endotoxins
Two additional tests are critical for research quality:
Residual solvents
Peptide synthesis uses organic solvents (DMF, acetonitrile, TFA). The COA should confirm that residual solvents are below safe thresholds. High residual solvent levels can interfere with cell-based assays and compromise research results.
Bacterial endotoxins
Endotoxin testing measures bacterial lipopolysaccharide contamination. This is essential for any peptide that will be used in cell culture or in-vitro biological assays. BioLabs Research lots are tested to 0.5 EU/mg or below.
What to watch out for
- Missing MS data - purity without identity is incomplete
- Self-tested lots — ask how identity/purity were measured and whether an independent lab was used
- No lot number - without traceability, the COA is meaningless
- Purity vs. the lab’s written spec — a number alone is not a grade label; match HPLC % to the intended method
- Outdated COAs - the COA should match the current lot in the vial
How BioLabs Research handles COAs
Testing panels can include HPLC, mass spectrometry, residual solvent and endotoxin testing, and a lot's COA lists the tests actually run. Lab COA PDFs are published per product where available in our COA library; others on request. If you need a COA for a specific lot before ordering, contact us at admin@biolabsresearch.co and we will provide it.