Buying research peptides is a documentation problem disguised as a shopping problem. The vials all look alike. The websites all say “purity.” What separates a supplier you can rely on from one you can’t is almost entirely paperwork: what’s tested, by whom, and whether you can check it yourself.
So here’s a working checklist. Ten questions, in the order we’d ask them, with the answers you want to hear and the answers that should send you elsewhere. Print it, bookmark it, forward it to your lab manager. It’s meant to be used.
1. Is every single lot tested, or just “the product”?
Peptide synthesis is a long chain of coupling steps, and quality varies batch to batch. A test from one lot tells you nothing certain about the next.
Good answer: “Every lot is tested before release, and each lot gets its own certificate.”
Red flag: A single dateless “representative” COA covering a product that’s been on sale for years.
2. Who does the testing, and can you name the lab?
In-house testing has a built-in conflict of interest: the person reporting the purity number profits from a high one. Independent testing removes that incentive. We’ve written a full breakdown of why independent third-party testing matters.
Good answer: A named, US-based independent lab whose name appears on the certificate.
Red flag: “Third-party tested” with no lab name anywhere. An unverifiable claim is a slogan.
3. Is the lab accredited to ISO/IEC 17025?
Accreditation means an outside body audits the lab’s methods, calibrations, and analyst competence on an ongoing basis. It’s the difference between “we have an HPLC” and “our HPLC results are validated and traceable.”
Good answer: Yes, with an accreditation body you can verify (A2LA, ANAB, and PJLA all publish searchable directories).
Red flag: Vague appeals to “certified labs” with no accreditation number and no way to look it up.
4. Does the COA show the exact lot number on my vial?
This is the single fastest check you can run. The lot number on the certificate must match the lot number printed on the product. If it doesn’t, the certificate describes some other batch, which is to say it describes nothing.
Good answer: Lot-matched COA in the box, plus a way to pull it up online by lot.
Red flag: No lot number on the COA, no lot number on the vial, or numbers that don’t match.
5. What does the test panel actually include?
Purity alone isn’t enough. A complete panel for a lyophilized peptide answers three separate questions:
- Purity (HPLC): what fraction of the peptide content is the target molecule?
- Identity (mass spectrometry): is the molecule actually the peptide named on the label?
- Endotoxin (LAL assay): what level of bacterial endotoxin is present?
Good answer: All three, on one certificate, for every lot.
Red flag: An HPLC chromatogram with no identity confirmation. A pure peak of the wrong compound is still the wrong compound.
6. How is the purity number calculated?
Most peptide purity figures are HPLC area percent: the target peak’s share of total detected peak area. That’s a legitimate method, but it has assumptions and limits worth understanding. Details matter, like the detection wavelength and the gradient used.
Good answer: The COA states the method, column, and detection parameters, and the chromatogram is included.
Red flag: A bare number like “99.9%” with no method, no chromatogram, and no lab shown. If you want the full picture of what these figures mean, read our guide on what 99% purity actually means.
7. Can I verify the certificate independently?
A PDF is easy to edit. Verification is what makes a certificate trustworthy. There are three levels of it: a public COA library you can browse by lot, a scannable code on the product linking to that lot’s results, and an accredited lab that will confirm the report number if you contact them.
Good answer: All of the above. At Elutide, every certificate is public in our COA library, and every insert carries a QR code resolving to a verification page for that exact lot.
Red flag: COAs available “on request” only, watermarked into illegibility, or with the lab’s name cropped out.
8. What quantity does the label actually describe?
A vial labeled “5 mg” can mean gross fill mass or net peptide content, and those differ. Lyophilized peptides also carry counterions (commonly acetate or TFA salts) and residual moisture, which are part of the mass but not part of the peptide.
Good answer: The vendor states whether the label refers to net peptide mass and reports counterion or peptide content data on the COA.
Red flag: No answer at all, or visible confusion about the question.
9. How is the product handled between the lab and my bench?
Analytical results describe the batch at the time of testing. Storage and transit determine whether the vial on your bench still matches them. Lyophilized peptides are far more stable than solutions, but heat and humidity are still the enemy.
Good answer: Sealed vials, clear storage guidance, prompt tracked shipping. (Ours ships free 2-Day Air on orders over $150, because a week in a hot truck helps no one.)
Red flag: No storage guidance anywhere on the site or insert.
10. What does the marketing language tell you?
Read the vendor’s copy as a diagnostic. Trustworthy suppliers talk about lots, methods, labs, and certificates. Untrustworthy ones talk about miracles.
Good answer: Sober catalog pages, visible documentation, terms defined.
Red flag: Claims about effects, meaningless quality buzzwords, or grade terminology borrowed from regulated medicine that has no defined meaning for research chemicals.
The Checklist, Condensed
| # | Question | Pass Looks Like |
|---|---|---|
| 1 | Every lot tested? | Per-lot certificates |
| 2 | Independent lab? | Named third party on the report |
| 3 | ISO/IEC 17025 accredited? | Verifiable in a public directory |
| 4 | Lot numbers match? | COA matches the vial exactly |
| 5 | Full panel? | HPLC + mass spec + LAL |
| 6 | Method disclosed? | Chromatogram and parameters shown |
| 7 | Independently verifiable? | Public library + lot QR + lab confirms |
| 8 | Label mass defined? | Net peptide content addressed |
| 9 | Handling and shipping? | Sealed, guided, fast |
| 10 | Honest marketing? | Documentation, not promises |
Where Elutide Stands on All Ten
We designed our catalog to pass this checklist before we ever published it. Every batch of every product, from BPC-157 and TB-500 to NAD+ and Selank, is tested by an independent, US-accredited third-party lab for HPLC purity, mass-spec identity, and endotoxin. A lot-specific COA ships in every box, the insert QR resolves to that lot’s public verification page, and the full archive lives in our COA library.
Ask us all ten questions. We like answering them. That’s rather the point of “Purity You Can Verify.”
For Research Use Only. Not Intended for Human Consumption.