Buyer's guide
How to verify research peptide quality
Eight checks that separate suppliers with evidence from suppliers with claims. They apply to anyone selling research peptides — including us. Hold every supplier to all eight.
1. Ask for the Certificate of Analysis before you pay
A trustworthy supplier publishes a batch-specific Certificate of Analysis (CoA) BEFORE purchase — not on request afterwards. The CoA should name the exact compound, the batch or lot number, the testing laboratory, and the test date. If a supplier cannot show you a CoA for the batch you would receive, that is a decisive red flag.
2. Check that testing is third-party, not in-house
In-house purity claims are unverifiable. Look for an independent laboratory's name on the CoA and confirm the lab actually exists. Third-party testing means the supplier cannot grade its own homework.
3. Look for both HPLC purity and mass-spec identity
High-performance liquid chromatography (HPLC) establishes purity — the percentage of the sample that is the stated compound; research-grade material should test at 98–99% or higher. Mass spectrometry (MS) establishes identity — that the molecule's mass matches the stated compound. Purity without identity, or identity without purity, is half an answer.
4. Match the CoA to the vial
The batch or lot number printed on the CoA should match the label on the vial you receive. A generic CoA with no batch linkage could describe any batch from any time.
5. Verify the compound's identifiers
The product listing should state the CAS registry number and molecular formula, and they should match the CoA and the scientific literature. Suppliers who publish identifiers invite verification; suppliers who omit them avoid it.
6. Check handling and cold-chain claims
Lyophilized peptides should be stored at −20 °C protected from light, and reputable suppliers say so plainly. Vague or absent storage guidance suggests the seller does not handle the material carefully either.
7. Confirm research-use compliance language
Legitimate research suppliers state clearly that products are for laboratory research use only and are not for human or veterinary use. Sellers who market research compounds with consumption or dosing guidance are operating outside the law — treat everything else they claim accordingly.
8. Test the support channel before ordering
Send a pre-sales question — about a CoA, a batch, or shipping. A supplier who answers quickly and specifically before the sale is far more likely to stand behind an order after it.
Frequently asked questions
- What is a Certificate of Analysis (CoA)?
- A CoA is a document from a testing laboratory that records what a specific batch of material is and how pure it is. For research peptides it should include the compound name, batch/lot number, HPLC purity result, mass-spec identity confirmation, the testing lab, and the test date.
- What purity should a research peptide have?
- Research-grade peptides are typically ≥98% pure by HPLC; high-quality suppliers test at ≥99%. The number itself matters less than whether it was measured by an independent laboratory on the batch you actually receive.
- Why does third-party testing matter?
- Because an in-house result is a claim, not evidence. Independent laboratories have no stake in the sale, so their HPLC and mass-spec results are verifiable evidence of what is in the vial.
- What are the biggest red flags when choosing a peptide supplier?
- No published CoA (or CoA only after purchase), purity claims with no named laboratory, missing CAS numbers and molecular data, generic CoAs with no batch linkage, no research-use-only compliance language, and dosing or consumption guidance — which is illegal for research compounds.
- Does Woosh Labs meet this checklist?
- Mostly, and we will say where we do not. Every Woosh Labs batch is tested by an independent third-party laboratory with HPLC and mass spectrometry, every listing carries its CAS number and molecular data, and all products are sold strictly for laboratory research use. On step one we fall short of our own bar: the batch CoA ships with your order rather than being posted on the product page, so before buying you have to request it at info@wooshlabs.com. Publishing every batch CoA on the listing is work in progress. We publish the checklist so you can hold us — and anyone else — to it.
Published by Woosh Labs. All products referenced are for laboratory research use only and are not intended for human or veterinary use. This guide is informational and is not medical, legal, or purchasing advice.