Information only. We do not sell products or give medical advice. Consult a licensed physician / healthcare professional.
Most guides teach you to read a Certificate of Analysis once it lands in your inbox. This one is about the step before that: how to make a supplier hand it over. Exactly what to request, the words to use, and how to check the batch the moment it arrives. Information only — we do not sell.
The method
A Certificate of Analysis is not a favour — it is the minimum a serious supplier already has on file. Ask in this order and you separate the sellers who test their batches from the ones who improvise.
Request the COA for the exact lot number you would receive. If a vial isn't assigned yet, ask which lot ships and for that lot's certificate — a generic PDF proves nothing about your unit.
"Please send the Certificate of Analysis for the specific lot I'll receive."
Ask who issued it. In-house "QC" is the seller grading its own work. A meaningful COA comes from an independent, accredited laboratory, and you can ask for the ISO/IEC 17025 reference.
"Which independent lab issued this, and what is its ISO 17025 accreditation?"
Headline numbers are easy to type. Ask for the HPLC chromatogram and the LC-MS mass spectrum as images. If the supplier can send a percentage but not the chart behind it, that gap is your answer.
"Please attach the HPLC chromatogram and the LC-MS spectrum, not just the numbers."
When it arrives, compare the lot number on the certificate to the number printed on the vial. If they don't match, the document is describing a different batch than the one in your hand.
Read the vial's lot number, then confirm it appears on the COA — verbatim.
The ask list
When you write to a supplier, this is the checklist to send with your request. Every line is something an accredited lab already measures — so a genuine batch certificate can supply all of it.
The decision
Once the response lands, you're judging the supplier as much as the document. These are the signals that tell you to proceed — and the ones that tell you to stop asking and leave.
What you're asking for
A complete certificate reports purity, identity, water, and endotoxin — four methods, four results. When you request a COA, these are the four fields to confirm are present.
The proportion of target compound, with the chromatogram attached so the main peak is visible.
Molecular mass confirmation proving the compound is what the label claims — not an analogue.
Residual water content, which lowers the true net peptide mass in lyophilized material.
Bacterial endotoxin in EU/mg or EU/mL — relevant for any cell-culture or in-vivo research use.
Why the source matters
Every step in this kit circles back to one question: who ran the test? A seller issuing its own Certificate of Analysis is grading its own work. In-house "QC" is not the same as an independent, accredited laboratory. Only a third-party lab — ideally ISO/IEC 17025 accredited — produces a certificate free of commercial incentive, using validated and auditable methods.
That is why the request is worded the way it is. You are not being difficult; you are asking for the ordinary paperwork any serious batch already carries. If it cannot be produced, the absence is itself the finding. International reference points — WHO quality principles, ISO/IEC 17025 lab competence, and pharmacopeial (USP) methods — form the shared vocabulary a genuine COA speaks.
Framing: WHO quality principles · ISO/IEC 17025 · USP methods. Updated July 2026.
Questions
Ask in writing for the Certificate of Analysis tied to the exact lot number you would receive. Request that it be issued by an independent, accredited laboratory, and ask for the HPLC chromatogram and the LC-MS mass spectrum as attached images — not just headline percentages. A supplier that verifies its batches will send these without friction.
Ask for the lot number, purity by HPLC with the chromatogram attached, identity confirmation by LC-MS, water content by Karl Fischer, endotoxin by the LAL assay, and the issuing laboratory's ISO/IEC 17025 accreditation reference. Every claim should tie back to a named lab and the specific batch.
A generic sheet with no lot number, no chromatogram, and no named issuing lab is marketing, not a Certificate of Analysis. Politely ask again for the batch-specific document. If it cannot be produced, treat that as a red flag and reconsider the source.
The lot number is the traceability key. A COA only proves something about your material if the lot number on the certificate matches the lot number printed on the vial you receive. Always cross-check the two before you trust the document.
No. Get the COA is an information and education resource. We do not sell products, do not capture email, and do not give medical advice. We teach you how to request and verify a Certificate of Analysis. Consult a licensed physician before considering any use.
The request kit
The kit collects the four moves, the copy-ready ask list, and the green-light / walk-away signals into one place — plus the supplier we checked against everything above.
Peptides discussed here are research materials where applicable — not consumer goods and not approved medicines. Legal status varies by country. Nothing here recommends use, dose, or a source of supply. Anyone considering these substances should consult a licensed physician who can assess their individual situation.