A buyer's guide to peptide purity, COAs, and sourcing — how to vet a supplier before you buy.
If you've shopped for research peptides, you've seen "research-grade," "premium," and "99% pure" on nearly every site. The phrases sound interchangeable. They aren't. The difference between a vial you can trust in a controlled study and one you can't comes down to a few verifiable things — and most of them are written down, if you know where to look.
There's no single governing body that stamps a peptide "research-grade," so the term is only as meaningful as the documentation behind it. A credible supplier should be able to show three things: an identity confirmation, a purity measurement, and independent third-party verification. When a brand uses "research-grade" but can't produce those documents, the word is doing marketing work, not scientific work.
A COA is the lab report that accompanies a specific batch. Learning to read one is the single most useful skill for vetting a supplier.
A real COA is tied to a specific production lot. The lot on the document should match the lot on the vial — a generic, undated COA reused across every order is a red flag.
This confirms the molecular weight of the compound matches the expected target. It answers the most basic question: is this actually the peptide on the label?
High-Performance Liquid Chromatography separates the sample into its components and reports the target peptide as a percentage of the total. A purity figure should be backed by an actual chromatogram — the graph — not just a number typed onto a page.
One clean, dominant peak indicates a high-purity sample; a cluster of smaller peaks indicates impurities. Reputable suppliers publish the graph, not just the summary line.
A supplier reporting its own purity has an obvious incentive problem. Independent, third-party analysis removes that conflict. When you're comparing two vendors with similar prices and claims, the one publishing batch-specific, third-party COAs is the defensible choice for research use.
In controlled research, impurities are variables you didn't intend to introduce. Higher, verified purity narrows that uncertainty — a methodological argument, not a health one.
At Midas Peptides, we publish third-party Certificates of Analysis and hold our catalog to a research-grade sourcing standard because verifiable documentation is the only version of "premium" that means anything. All products are sold for laboratory research use only and are not for human consumption.
Explore the catalog → See our COAs →