How to Read a Tesamorelin COA: Identity, Purity, and Net Peptide Content
Tesamorelin is one of the larger peptides in a research catalog, and that size changes what its certificate of analysis (COA) is telling you. If you can read three parts of the certificate, identity, chromatographic purity, and net peptide content, you know what is actually in the vial. Here is how to do that for this specific compound.
What Tesamorelin is, by identity
Tesamorelin is a synthetic 44-amino-acid peptide. Structurally it is an analog of human growth-hormone-releasing hormone (GHRH, also written GRF 1-44) carrying a trans-3-hexenoyl group on its N-terminus, a modification that is part of what a COA identity section confirms. Its registry identifiers are fixed and checkable: PubChem CID 16137828, CAS 218949-48-5, molecular formula C221H366N72O67S, and an average molecular weight of about 5,136 g/mol. Those are identity facts, not marketing, and you can verify every one against a public registry before you trust a certificate that claims to describe this molecule.
Chromatographic purity is not net peptide content
This is the part most people miss on a large peptide. Chromatographic purity, measured by HPLC, tells you what share of the peptide material in the vial is the target molecule rather than related impurities. It is usually the headline percentage. Net peptide content is a different question: what share of the dry powder is actually peptide, as opposed to the acetate counterions and bound water that come with a peptide salt. A 44-residue peptide supplied as an acetate salt can be very high in chromatographic purity and still have a meaningful fraction of the powder mass that is not peptide, simply because of the salt and water. The two numbers answer different questions, and net peptide content comes from amino acid analysis, not from the purity chromatogram.
Identity confirmation for a 44-mer
For a molecule this size, identity is confirmed on its own, separate from the purity number. The certificate should establish that the material is the expected sequence with the expected N-terminal modification, typically supported by a mass measurement matching the roughly 5,136 g/mol figure above. A high purity percentage on unconfirmed identity is not enough; the point of reading both is that you know the certificate is describing the right molecule and describing it cleanly.
What our certificates show for Tesamorelin
On our public register, Tesamorelin lots have measured chromatographic purity of 99.39% (UMP-1700427), 99.40% (UMP-4250856), and 99.32% (DPS-4065773), each tested by a third-party lab and each with its own downloadable COA. You do not have to take those numbers on faith; they sit on the open register next to every other lot we have published.
Check the lot in your vial
The number that matters is the one for the exact lot you received. Find the lot number on the vial and enter it on our verification page to pull that lot’s COA, or read the whole register first if you have not bought anything yet. If you want the general skill, our guide on how to read a COA walks through every section, and our post on what >98% purity actually means explains why we publish the measured number for every single lot. You can also browse the product itself: Tesamorelin.
References: PubChem CID 16137828 and CAS Registry Number 218949-48-5 for identity, formula and molecular weight; compendial guidance (USP) for chromatographic purity and for net peptide content by amino acid analysis.
Related reading: what is Tesamorelin, identity and research context.
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