Can a 99 percent area figure identify the sequence?

No. The area figure is purity under the stated method. Sequence identity is the mass comparison, when that comparison is on the report.

Does a matching mass replace the purity line?

No. A mass match and an area percent answer different questions. Keep both, or mark the missing one as missing.

Glossary · 2026-09-24

Scientific lead: Alice Kay, Ph.D.

Purity versus identity on a peptide COA

Purity and identity are different questions on a peptide lot file. Purity, when it is reported, is usually an area percent from HPLC or UPLC: how the sample separated under that method. Identity is whether the observed mass matches a mass calculated from a stated sequence and a stated species. A high area percent does not repair a mass mismatch.

Read both lines, and record either line as absent when the PDF omits it. The method note is how peptide purity is measured. The chromatogram and the mass spectrum are the records behind those lines. Research-use only.

Frequently asked questions

Can a 99 percent area figure identify the sequence?: No. The area figure is purity under the stated method. Sequence identity is the mass comparison, when that comparison is on the report.
Does a matching mass replace the purity line?: No. A mass match and an area percent answer different questions. Keep both, or mark the missing one as missing.

Research-use only. BlueNex Labs does not provide medical or veterinary advice. Confirm your institution’s policies before purchase.