Quality Control
Reading HPLC purity on a peptide COA
What an HPLC purity number on a research peptide Certificate of Analysis actually reports — and why two labs can print different percentages for the same sequence.
3 min read · Updated 2026-08-21 · VaultLabs Research Editorial · Reviewed by VaultLabs compliance review
Research use only. For in vitro research use only. Not for human or animal consumption. Not for human consumption, medical use, or personal application.
What HPLC is doing
High-performance liquid chromatography separates components in a sample as they move through a column. On a peptide COA, the headline purity is usually the area of the main peak relative to other peaks under that method.
It is a chromatographic snapshot for one lot, on one instrument setup, on the date printed. It is not a clinical grade, a stability guarantee, or proof the material will behave the same in your assay.
Why methods are not interchangeable
Column chemistry, gradient, detection wavelength, and integration rules all change the reported number. A supplier COA and an in-house method can disagree without either being “wrong.”
When you compare vendors, compare method descriptions — not isolated percentages. How to read a peptide COA covers matching lot identifiers before you even look at the purity line.
How VaultLabs uses HPLC on published records
When a lot’s record is uploaded, HPLC purity may appear on that batch’s COA. Absence of an online chromatogram usually means the file is not published yet — not that the lot failed.
Your laboratory still sets acceptance criteria. VaultLabs does not interpret HPLC results for study design.