Reference

How to read a peptide certificate of analysis

A certificate of analysis (CoA) is a lab's report on one specific lot of a compound. A good one lets you check two things: that the vial holds the right molecule, and how pure it is.

What a complete CoA includes

• Lot or batch number that matches the label on your vial. A CoA without one can't be tied to what you received.
• Identity: compound name, sequence, molecular formula and theoretical molecular weight.
• HPLC purity: high-performance liquid chromatography separates the peptide from impurities. Purity is reported as the main peak's share of the total peak area, usually measured at 214 or 220 nm. The chromatogram itself should be attached, not just the number.
• Mass spectrometry (MS): confirms identity. The observed mass (by ESI or MALDI) should match the theoretical mass within the instrument's tolerance.
• Appearance: for example "white lyophilized powder".
• Testing lab, date and signature, ideally from a lab you can contact to confirm the report is genuine.

Purity is not the same as peptide content

HPLC purity measures how much of the peptide material is the target sequence. A lyophilized powder also contains counter-ions (such as acetate or trifluoroacetate) and some water, so the net peptide content by weight is lower than the purity figure. Some CoAs report both; when you need an exact quantity, peptide content is the number to use.

Red flags

• No lot number, or the same CoA shown for every lot.
• A purity figure with no chromatogram, or no mass spectrum.
• An observed mass that doesn't match the sequence.
• A testing lab that can't be identified or contacted.

Where Chainwell stands

Independent third-party testing has started. Each lab report is published on its compound's product page, under Quality & testing, as soon as it comes in. Where a product page has no report yet, no purity figure is shown until the supplier's specification is confirmed. See the peptide reference table for the identity data of every compound we carry.

Chainwell products are for in-vitro laboratory research only and are not for human or veterinary use.