How to Read a Peptide COA Without Getting Lost in the Numbers
HPLC purity, MS identity, net peptide content, and endotoxin notes — the four lines research buyers check first when a COA lands in their inbox.
COA literacy is now table stakes
In peptide research communities, “send the COA†is the default reply to almost every sourcing question. That only helps if the report is readable. Here is the Helix Peptide field guide we share with new institutional accounts.
HPLC purity
High-performance liquid chromatography estimates how much of the UV-active material is the main peak versus related impurities. For most research catalog peptides, buyers look for ≥98%. Longer or difficult sequences may land slightly lower — ask why, and request chromatograms when possible.
Mass spectrometry (identity)
MS confirms the observed mass matches the expected molecular weight. A clean purity number without identity confirmation is incomplete. Helix Peptide includes LC-MS identity on release packages for catalog and custom lots.
Net peptide content
Lyophilized powders contain peptide plus residual water and counter-ions. Net peptide content (often via nitrogen analysis) tells you how much of the weighed material is actual peptide. This matters for assay prep even when HPLC purity looks excellent.
Appearance, lot, and dates
- Lot / batch number — must match the vial.
- Manufacture / test / retest dates — confirms the paperwork is current.
- Appearance — typically a white to off-white lyophilized cake or powder.
Optional but valuable lines
GMP or injectable-adjacent programs often add endotoxin (LAL), residual solvents, and moisture (Karl Fischer). Research-use lots may omit some of these; know your protocol requirements before ordering.
Want a sample Helix Peptide COA layout? Visit Quality & Certs or request documentation from our QA team.