tesamorelin
How to Read a Tesamorelin COA
A practical guide to reading a tesamorelin certificate of analysis: what purity, identity, and testing sections mean, and how to compare listings.
Medically reviewed by Catherine Dumont, MD, physician and clinical researcher — Last reviewed
Catherine Dumont, MD is a physician with clinical and research training in endocrinology and growth hormone therapeutics, with post-graduate research in GHRH analog applications and growth hormone axis disorders.
A certificate of analysis, or COA, is the document a testing lab issues after examining a sample from a specific production batch. Learning how to read a tesamorelin COA means knowing which sections describe the material itself, which describe the test methods used, and which numbers actually matter when comparing one listing against another. Most COAs look similar at a glance, but the details that separate a useful document from a decorative one are easy to miss if you have not looked at more than one or two.
What a COA Is Actually Reporting
A COA is a snapshot of one batch, not a permanent guarantee about every vial that ever ships under a given product name. The document ties a batch or lot number to a set of test results produced by a lab, on a sample date, using specific methods. If a listing shows a COA but the lot number on the document does not match the lot number on the vial or packaging in front of you, the document is not actually verifying what you are holding.
Reputable listings link each product to a COA for the specific batch currently being sold, not a generic or outdated file reused across multiple production runs. When a site posts one COA and keeps it up indefinitely regardless of restocks, that is a sign the document may not reflect current inventory.
Identity Testing
The identity section confirms that the sample contains the peptide it claims to contain, distinct from confirming how much of it or how pure it is. This is typically done with mass spectrometry, which compares the mass of the sample’s molecules against the expected mass of the target peptide’s sequence.
A COA that reports identity as “pass” or “confirmed” without showing the underlying mass value gives you less to evaluate than one that lists the measured mass alongside the expected mass for comparison. Some documents include the amino acid sequence tested against, which allows a reader to check that the reference sequence used by the lab matches the compound being described.
Purity Testing
Purity is usually reported as a percentage, most often generated through high-performance liquid chromatography (HPLC). HPLC separates the components of a sample by how they travel through a column, producing a chromatogram where the target peptide shows up as a peak. The purity percentage reflects how much of the total peak area belongs to the target compound versus other detected substances.
A HPLC purity figure describes chemical purity, not sterility, and it says nothing about endotoxins or microbial contamination on its own. Some COAs bundle several types of testing into one document, and it matters which type of test produced which number. A chromatogram image included with the report lets a reader confirm there is a single dominant peak rather than several smaller ones, which a bare percentage alone cannot show.
| COA element | What it measures | What it does not measure |
|---|---|---|
| Identity (mass spec) | Whether the molecule matches the target sequence | Purity or concentration |
| Purity (HPLC) | Percentage of target compound in the sample | Sterility or endotoxin levels |
| Endotoxin test (LAL) | Bacterial endotoxin presence | Peptide identity or purity |
| Sterility test | Presence of viable microorganisms | Chemical composition |
Batch and Date Information
Every COA should show a lot or batch number, a sample or test date, and ideally an issuing lab name that can be independently searched. A document missing all three of these is difficult to tie to anything specific. The test date also matters separately from the manufacturing date, since a peptide sample tested shortly after production reflects different handling conditions than one tested after extended storage.
When comparing two tesamorelin listings, matching the lot number on the COA to the lot number on the product itself is the step that most often gets skipped. A vial with no visible lot marking makes this comparison impossible, regardless of how detailed the posted COA appears.
Reading the Testing Lab’s Credentials
Independent third-party labs that test on behalf of a seller carry more weight than in-house testing performed by the seller itself, since the lab has no direct financial interest in the result. Some labs publish their own accreditation details or can be verified against public registries, which gives a reader a way to check the document’s origin rather than taking the seller’s word for it. If the COA lists a lab name with no way to confirm it independently, that reduces how much the document can be verified against outside information. For a broader reference on how listings describe testing and documentation terminology, the tesamorelin reference page covers these terms in more general form.
Comparing Two Listings Side by Side
When two sellers list the same nominal product, the COA is often the fastest way to see a real difference between them. A useful comparison checks whether both documents come from named, checkable labs, whether both report a purity figure with a chromatogram rather than a number alone, and whether both include a lot number that matches current stock. A listing that provides all three is giving a reader more to verify than one that provides a purity percentage and nothing else.
Some networks of sites cover the same compound from different angles, and cross-referencing how pricing and documentation are described elsewhere can be useful context; a peer tesamorelin listing catalog looks at how tesamorelin listings are priced, which is a related but separate question from how they are documented.
Common Gaps to Watch For
A few patterns show up repeatedly in COAs that are less useful than they appear. A document with no chromatogram image, only a stated percentage. A lot number that does not appear anywhere on the physical product. A test date far removed from any indication of when the batch was produced or shipped. A lab name that does not turn up in any independent search. None of these gaps prove a product is mislabeled, but each one removes a way of checking the claim, which is the entire purpose of posting a COA in the first place.
Summary
Reading a tesamorelin COA well means separating identity testing from purity testing, checking that the lot number on the document matches the product in hand, and looking for a named, independently checkable lab behind the results. A COA with a bare percentage and no supporting detail verifies far less than one with a chromatogram, a matched lot number, and a traceable testing lab. The document is only as useful as the specifics it discloses.