Not all 99% purity claims are equal. Learn how peptide purity is measured, what HPLC testing means, and why third-party verification matters for your research.
May 20, 2026 | 8 min read
The Problem With Purity Claims
When a peptide supplier advertises “>99% purity,” it sounds definitive. But without context, that number is nearly meaningless. Purity is a measurement — and like all measurements, it depends entirely on the method used, the equipment calibrated, and who is doing the measuring.
In the RUO peptide market, purity claims range from rigorously verified third-party HPLC data to numbers that were simply typed into a product description with no supporting evidence. Understanding the difference is critical for any researcher who cares about reproducibility.