How to read a certificate of analysis for a research peptide
A certificate of analysis reports test results for one lot of a material. For a peptide the core results are HPLC purity, a mass spectrometry identity check and, where reported, net peptide content. Each number answers a different question, and the certificate applies only to the lot it names.
Research-use information. This page summarises published literature and regulator records. It is not guidance for use, not medical advice, and not a statement that any material is suitable for use in people or animals.
What is a certificate of analysis?
A certificate of analysis (CoA) is a document from a testing laboratory that lists the tests run on one lot of a material and the result of each. It names the lot, the material, the laboratory and the test date. A CoA is evidence about that lot only, and it says nothing about any other lot of the same compound.
What does HPLC purity tell a reader?
High-performance liquid chromatography separates the components of a sample. For a peptide the report gives purity as the share of the signal, by peak area, that belongs to the main component. A purity of 99 percent means that 99 percent of the detected signal is the main peak. It does not say how much of the weighed solid is peptide, because salts and water are not seen in the same way.
What does mass spectrometry confirm?
Liquid chromatography coupled to mass spectrometry (LC-MS) measures the mass of the molecules in the main peak. If the measured mass matches the calculated mass of the expected sequence, the result supports the identity of the compound. Every compound page on this hub lists the molecular formula and average molecular weight that the measured value is compared with.
What is net peptide content, and how is it different from purity?
Net peptide content is the share of the weighed solid that is peptide, after counterions such as acetate and after bound water. It is lower than 100 percent for every peptide. Purity and net content answer different questions: purity is about what else is present in the peptide signal, and net content is about how much of the powder is peptide.
Which identifiers must match?
Four items link a certificate to a vial. All four must agree before a result is relied on.
- The lot number on the vial and on the certificate.
- The compound name and, where given, the sequence or formula.
- The laboratory name and the test date.
- The tests reported: purity, identity, and net content where stated.
What can a certificate not say?
A certificate reports only the tests it lists. It is not a statement that a material is suitable for any use in people or animals, and it does not cover tests that are not listed on it, such as sterility or endotoxin, unless they appear there.
Where can a certificate be looked up?
The shop provides a lookup by lot number. The terms used above are defined in the glossary.