Short answer: suppliers can sell products with the same name but differ in what they can prove: how deeply each batch is tested, whether results are batch-specific and verifiable, how clearly they document sourcing and storage, and whether they operate within research-use-only rules.
Testing depth
| Level | Typical tests |
|---|---|
| Minimal | Purity only, or no testing shown |
| Standard | Identity (MS) + purity (HPLC) |
| Extended | Identity, purity, net content, endotoxin, microbial and heavy-metal screens |
Batch transparency
Some suppliers show one old COA for each product. Others publish a COA for each lot and print the lot number on the vial. Batch-level transparency lets you connect a result to the product you receive.
Who ordered the test
The client named on a COA shows who submitted the sample. Some suppliers commission their own tests; others rely on reports ordered by manufacturers or distributors. Both exist in the market, and the client field tells you which one you are looking at.
Documentation
Look for clear specifications, storage guidance, safety data where relevant, and readable HTML records rather than only image-based PDFs.
Compliance and marketing
Research suppliers should describe research context, not health outcomes. Medical claims, dosing instructions or personal-use marketing are signs of a supplier operating outside research-use rules.
Service
Fulfillment speed, packaging, communication and how problems are handled also vary widely.
Use our supplier evaluation checklist to compare suppliers side by side.
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.