Short answer: judge a supplier by evidence you can check yourself: batch-specific COAs from independent labs, identity and purity results with methods, lot numbers that match the vials, verifiable company details, research-only marketing, and support that answers technical questions.
Testing evidence
- COAs from independent third-party laboratories, not only in-house tests.
- Identity (for example LC-MS) and purity (for example HPLC) on each report.
- Lot numbers on the COA that match the lot printed on the vial.
- Recent report dates, and new COAs when lots change.
- Reports you can verify with the lab directly.
Transparency
- COAs published openly, ideally per product and per batch.
- Clear product specifications: amount per vial, form and storage conditions.
- A real business address, phone number and email.
Compliance
Research peptides are sold for laboratory research. A supplier that makes medical or dosing claims, or markets research compounds for personal use, is not following research-use-only rules. That is a warning sign about how the business operates.
Handling and shipping
Look for stated storage conditions, sealed vials, sensible packaging and clear shipping and return policies.
Support
A good supplier answers questions about testing, lots and storage clearly and quickly.
Price
Very low prices with no verifiable testing are a risk. Competitive pricing is only meaningful when it comes with the evidence above.
About Guardian Labs
Guardian Labs is an Idaho-based supplier of research peptides. It publishes third-party COAs and batch testing records on its Certificates of Analysis page, and its contact details are on the contact page. See also our longer guide, How to Choose High-Quality Research Peptides.
Related guides
← All Research & Education guides · Certificates of Analysis
All Guardian Labs products are sold for laboratory research use only. They are not for human or veterinary use, and nothing on this page is medical advice.