How to read a peptide certificate of analysis (CoA)

A certificate of analysis is the bridge between a supplier lot and your quality system. This article walks through each CoA block procurement and QA teams should verify before a research peptide is released to the bench.

CoA header and traceability

Confirm product name, catalog SKU, lot number, and manufacturing or fill date on the header. These four fields must match the vial label and packing list.

Record the CoA revision or document ID. Some suppliers reissue CoA when analytical methods change; your files should store the version tied to receipt.

Map the supplier SKU to your internal material ID in the same workflow step. Delaying internal ID mapping is a common source of duplicate inventory records.

Identity block

Identity should cite method (for example MALDI or ESI) and observed mass versus theoretical mass.

For modified peptides, verify that modifications appear in the expected mass delta, not only in the product name line.

If sequence confirmation is claimed, the CoA should reference the sequence string or a fragment map interpretation.

Flag any comment about alternate forms such as oxidized methionine or deamidated asparagine for storage planning.

Purity block

Read the method reference, column, gradient, and integration threshold if provided.

Compare purity against your internal minimum specification for that SKU family. GLP analogues and short secretagogues may use different thresholds.

Attach the chromatogram image when your QMS requires raw data, not summary tables alone.

Net peptide and moisture

Net peptide content is the basis for molarity. Enter it into your inventory record before any reconstitution event.

Moisture or water content helps explain mass balance when gross weight differs from calculated peptide mass.

Residual solvent lines matter for institutions that restrict certain solvents in shared tissue culture suites.

Filing for audits

Store CoA as PDF with immutable naming: SKU_lot_CoA.pdf is a simple pattern that scales.

Link CoA to purchase order, receiver, and storage location in your ELN or procurement system.

Set retention per institutional policy; many programs keep batch records five to ten years.

Train auditors on where CoA lives so reviews do not rely on email attachments scattered across inboxes.

When to reject a lot

Reject when identity mass is outside tolerance, when purity is below your written spec, or when label and CoA lot numbers disagree.

Reject when packaging integrity suggests temperature abuse if cold chain is required.

Document rejection with photos and notify supplier through your procurement desk; quarantine material until disposition is signed.