Quality
Most research peptide suppliers publish a purity claim and ask researchers to take it on faith. Rewerk publishes a Certificate of Analysis for every batch — and the full COA library is public.
How we verify quality
Purity by HPLC
Every batch is analyzed by high-performance liquid chromatography (HPLC). HPLC separates the synthesized peptide from process-related impurities (truncated sequences, deletion peptides, residual solvents) and quantifies the main peak as a percentage of total area. We require a minimum of 99% purity for every lot we ship.
Identity by mass spectrometry
Purity alone doesn't tell you what's in the vial. Mass spectrometry confirms molecular weight against the expected mass of the target peptide, verifying identity at the amino-acid sequence level. Every batch is paired with a mass spec result and that result is published on the COA.
Independent testing
Our analytical work is performed by a third-party laboratory. We do not self-certify. The COA you receive is issued by the testing lab, not by Rewerk.
Per-batch documentation
COAs are issued per batch, not per product line. Each document names the compound, batch number, manufacturing date, verified purity, analytical method, testing laboratory, and date of analysis. The batch number on the COA matches the batch number on the vial label.
How to verify your batch
The lot number is printed on every vial label. Cross-reference it with the COA published on the product page or the searchable COA library. If something doesn't line up — or you'd like the raw chromatograms — contact us with the lot number and we'll send the full record.
Research use only
All products are sold strictly for in vitro laboratory investigation by qualified researchers. They are not drugs, biologics, food, cosmetics, or dietary supplements, and they are not intended for human consumption, veterinary use, diagnostic use, or any clinical application. No statement on this site has been evaluated by the U.S. Food and Drug Administration.