What is a good purity level for a research peptide?

Many suppliers set a release threshold at 98 to 99 percent or higher, measured by HPLC. The right threshold depends on the sensitivity of your research, but the figure is only meaningful when it is independently measured and reported on a lot-matched Certificate of Analysis.

What is the difference between HPLC and mass spectrometry on a COA?

HPLC measures purity, the percentage of the sample that is the intended peptide. Mass spectrometry confirms identity, whether the molecule's measured mass matches the expected mass. A complete COA reports both, because a sample can be highly pure yet be the wrong compound.

Should every batch have its own COA?

Yes. Purity and identity can vary between production lots, so a COA is only meaningful when it is generated per batch and matched to the lot number printed on your specific vial.

BUYING GUIDE 7 MIN READ

How to Read a Peptide Certificate of Analysis (COA)

A peptide Certificate of Analysis (COA) is an independent laboratory report that documents, for one specific production lot, the peptide's measured purity (by HPLC), its confirmed molecular identity (by mass spectrometry), and its physical characteristics. To read one, match the lot number to your vial, confirm the HPLC purity meets the stated threshold, verify the mass-spec observed mass matches the theoretical mass, and check that the overall result reads PASS.

Lot number and product identity

The top of a COA identifies the product and, critically, the lot or batch number. This number must match the one printed on your vial. A COA that is not lot-matched tells you nothing about the specific material in your hand, because purity varies between production runs.

HPLC purity

High-performance liquid chromatography separates the components of a sample and reports the target peptide as a percentage of the total. This is the headline purity figure. A chromatogram shows a dominant peak for the intended peptide; smaller peaks are impurities. A reputable report states both the percentage and the method conditions.

Purity thresholds matter for reproducibility: the higher and more consistent the purity, the fewer confounding variables in your research.

Mass spectrometry identity

HPLC tells you how pure the sample is; mass spectrometry tells you whether it is the right molecule at all. The report lists a theoretical (expected) molecular mass and an observed mass. When these agree within tolerance, the peptide's identity is confirmed. Purity without identity confirmation is incomplete.

Appearance, and the overall result

The COA also records physical characteristics such as appearance (for example, white lyophilized powder). Finally, an overall result (typically PASS/FAIL) summarizes whether the lot met every release specification. Treat a COA with a passing result, matched lot number, and both HPLC and MS data as the baseline standard, not a bonus.

All products are intended strictly for in-vitro laboratory research and development use only. Not for human or veterinary use, not a drug, food, or cosmetic, and not intended to diagnose, treat, cure, or prevent any disease.