How to Read a Certificate of Analysis

A certificate of analysis (COA) is the single most useful document a research supplier can give you. It is the lab record for one specific production run, and it should always be tied to the lot number printed on the vial in your hand. If a supplier publishes one generic COA for every batch of a compound, that document tells you nothing about what you received.

Start with the header. The lot number, compound name, manufacture date and testing laboratory should all be present. Cross-check the lot against your label before reading any further — a mismatch means the document does not describe your material.

Next comes HPLC purity. High-performance liquid chromatography separates the sample into its components and reports each as a percentage of total peak area. Atlas targets ≥99% for every research compound we release. Look at the chromatogram itself, not just the summary number: a clean single dominant peak with a flat baseline is what you want to see.

Mass spectrometry confirms identity. The measured molecular weight should match the theoretical weight of the sequence within a fraction of a dalton. Purity without identity is meaningless — a 99% pure vial of the wrong peptide is still the wrong peptide.

Finally, review water content (Karl Fischer), residual solvent and endotoxin results where applicable. Lyophilized powders carry some residual moisture; excessive water shortens shelf life and can indicate a rushed drying cycle.

Every Atlas lot ships with a batch-specific COA available through our lookup tool. If you ever cannot match a document to your vial, contact us with the lot number and we will send the full report.