What is a COA and how is purity verified?
What a Certificate of Analysis tells you about a research peptide, and how HPLC and mass spectrometry verify identity and purity.
A Certificate of Analysis (COA) is the paper trail between a supplier's claims and a batch's reality. It reports the measured results of analytical testing performed on a specific production batch, so a researcher can verify that what is in the vial matches what is on the label.
How does HPLC measure purity?
High-performance liquid chromatography separates a dissolved sample into its components as it passes through a packed column. The target peptide produces a peak at a characteristic retention time; impurities produce additional peaks. Purity is reported as the percentage of total peak area belonging to the target compound — ≥98% is the common research-grade threshold.
How does mass spectrometry confirm identity?
Purity alone doesn't prove the compound is what it claims to be. Mass spectrometry measures the molecular mass of the sample and compares it to the theoretical mass of the intended sequence. A match confirms identity; a mismatch means the wrong molecule is in the vial regardless of how pure it is.
What should you look for on a COA?
- A batch or lot number that matches the vial in your hand.
- The test methods used (HPLC for purity, MS for identity).
- Measured results, not just a 'pass' checkbox.
- The testing date and the laboratory that performed the analysis.
Third-party tested. COAs available on request. Every ENOS PetBio batch is documented, and we're happy to share the analysis for the batch you receive.
Common questions
What is a Certificate of Analysis?+
A COA is a batch-specific document reporting the results of analytical testing on that batch — typically identity, purity, and appearance — against the supplier's specification.
What purity should a research peptide have?+
Most research applications call for ≥98% purity by HPLC. The COA reports the measured value for the specific batch, not a generic claim.
What's the difference between HPLC and mass spectrometry on a COA?+
HPLC measures purity — how much of the sample is the target peptide versus impurities. Mass spectrometry confirms identity — that the molecule's mass matches the intended sequence.
For laboratory research use only. Not for human or veterinary consumption.