Anyone who reads supplement labels already understands the value of transparency. Research materials have a counterpart to that label, called a certificate of analysis, or COA. The catch is that a COA can be a genuine record of a measured batch or a decorative PDF with a logo on top. Telling them apart takes a little practice.
This piece walks through what a credible COA contains, what each analytical method can and cannot show, and how the identity details of one compound, the 29 amino acid peptide sermorelin, should line up with the paperwork. As a concrete example of the open format, Vive Peptides, a US-based supplier of research-grade peptides, has its peptides compounded at a US-based lab that adheres to cGMP standards and holds a purity specification of 99% or higher by HPLC. Everything it sells is strictly for laboratory and research use only and is not approved for human consumption, and nothing here is guidance for use in people or animals.
How do you read a peptide COA?
Read it in this order: confirm the laboratory, compound, lot number and test date; check the HPLC purity against the chromatogram; confirm the mass on the spectrum; then match the lot and fill size to the vial. A certificate is a laboratory document that reports measured results for one specific batch against a stated specification. It is a record of measurement, not a promise about a brand. The most useful COAs are boring: they name the lab, the compound, the lot, the date and the method, then report a result. The least useful show a single large number and nothing around it.
What does HPLC purity actually measure?
HPLC purity measures what share of the detectable material in a sample is the main compound rather than something else that separates from it. In high-performance liquid chromatography, a sample is carried through a tightly packed column under pressure. Different molecules move at different speeds, so they leave the column at different times, and a detector draws a peak for each one. Purity is typically reported as the area of the main peak relative to the total area of all peaks.
Before that number is trusted, the system itself has to behave. United States Pharmacopeia General Chapter 621, Chromatography, is the reference standard for HPLC system suitability, setting checks such as peak resolution, tailing factor and the precision of replicate runs.
HPLC purity also has limits. It does not confirm identity, since a clean peak can belong to the wrong molecule. It sees only what the detector responds to, so water, salts and counterions can be present without showing up as separate peaks. When you read a trace, look for a flat baseline, one dominant peak, and a legible label tying the file to a lot.
Why is mass spectrometry the other half of the story?
Mass spectrometry answers the question HPLC cannot: is this the molecule it claims to be? The instrument ionizes the sample and measures the mass-to-charge ratio of what results. For a peptide, the observed molecular weight is compared with the value calculated from its sequence and formula.
Take sermorelin as the worked example. It is the 29-residue fragment of growth hormone releasing hormone, GHRH(1-29) amide, where nearly full activity sits, and published preclinical studies have examined it as a GHRH analog in endocrine research. Its reference identity details are CAS number 86168-78-7, molecular formula C₁₄₉H₂₄₆N₄₄O₄₂S and a molecular weight of about 3357.9 g/mol. PubChem, the open chemistry database run by the US National Center for Biotechnology Information (NCBI), indexes sermorelin under that same CAS registry number, so the identifier on a certificate can be checked independently. A mass spectrum for a genuine sermorelin lot should land on the stated molecular weight within the instrument’s tolerance. If the paperwork lists a very different mass, the HPLC purity figure beside it is describing something else.
How do batch records tie a certificate to the vial you are holding?
Through the lot number and fill size printed on the vial, which should match the certificate exactly. A purity result belongs to the lot it was measured on, not to the product name in general. If a certificate carries no lot number, or the same certificate is reused across several lots, it documents nothing about the material actually on the bench.
A product page that publishes a full technical profile makes the matching easier. The page for this sermorelin research peptide with HPLC testing lists the CAS number, molecular formula and molecular weight above, describes the appearance as a white lyophilized powder, states purity of at least 99% by HPLC, and gives storage at -20°C, desiccated and protected from light. The CAS number can be verified against reference databases, the weight against the mass spectrum, the purity against the chromatogram, and the appearance against the sealed vial on arrival.
The Vive Peptides COA library listed 126 certificates across 25 peptides as of October 2026, searchable by peptide, lot number or size. Each lot is analyzed by an independent USA-based laboratory using HPLC with UV detection coupled to mass spectrometry, and each certificate shows the purity result, the mass confirmation and the chromatogram.
What does each document in a quality file really tell you?
Each document answers one narrow question, and none answers all of them. The comparison below shows how they fit together.
| Document | Question it answers | What it cannot tell you |
|---|---|---|
| HPLC chromatogram | How much of the detected material is the main compound? | Whether that compound is the right one |
| Mass spectrum | Does the measured molecular weight match the expected value? | How much of the sample is impurity |
| Lot-level COA | Which batch and fill size were tested? | Anything about a different lot |
| Technical profile | What are the CAS number, formula, appearance and storage conditions? | Whether a given lot meets them |
What should make a reader skeptical of a COA?
A certificate that cannot be tied to a named laboratory, a lot and a test date should make a reader skeptical. A few other patterns deserve the same caution:
- A purity number with no chromatogram attached.
- No identity confirmation, meaning no mass data at all.
- The same document appearing under different products.
- Results that contradict the technical profile, such as a mass far from the stated molecular weight.
A purity figure describes the material on the day it was tested. Conditions such as -20°C, desiccated and protected from light exist to keep the later reality close to the certificate. Lyophilized, freeze-dried powder in sealed vials is built around exactly that concern, and careless handling can undo the number printed on the page.
What to keep from all this
A real COA is specific. It names a lab, a lot, a method and a date, and it shows the chromatogram and the spectrum instead of summarizing them. HPLC tells you how clean the sample looks, mass spectrometry tells you what the molecule is, and the technical profile tells you what to expect when the vial arrives. A public, searchable library makes the lot-matching step simple, but the habit matters more than the source: ask for the lot, read the trace, check the mass.
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