How to read a certificate of analysis
A section-by-section walk through the lab report that ships with every lot.
A certificate of analysis, usually shortened to COA, is the lab report that describes one specific batch of a compound. It is the main piece of evidence a research buyer has about what is inside a vial, so it is worth knowing how to read one quickly and critically. This article walks through the sections you will usually find and what to check in each.
The header
The top of a COA normally names the compound, the lot or batch number, the amount per vial and the date of analysis. Some certificates also show the name of the testing laboratory and a report or sample ID. The first thing to do is compare the lot number on the certificate with the lot number printed on your vial label. If they do not match, the certificate does not describe your vial, and you should contact the supplier before going further.
Identity testing
Identity tests answer a simple question: is the material the compound it is labeled as? For peptides this is most often done with mass spectrometry, which measures the mass of the molecules in the sample. The report will usually show an expected molecular weight, calculated from the sequence, and an observed value. Close agreement between the two supports the identity of the material. Look for both numbers, not just a pass statement.
Purity testing
Purity is commonly measured by high-pressure liquid chromatography, or HPLC. The sample is separated into its components, and a detector records each one as a peak. The purity figure is the share of the total signal that belongs to the main peak. A chromatogram image is often attached, showing one large peak and any smaller ones. A purity value is meaningful only together with the method, so check that the certificate states how it was measured.
Other findings
Some certificates include extra fields, such as appearance, which describes how the material looks, or water content and counter-ion content. These are useful for interpreting the net amount of peptide in a vial, because the weighed material can include small amounts of water and salts alongside the peptide itself.
Dates, signatures and traceability
A good certificate shows when the test was run and who ran it. A signature or an analyst’s name, a lab name and a report ID make it possible to trace the finding. Keep each COA filed with your lab records under the lot number, so anyone reviewing your work later can see exactly which batch was used.
Questions to ask
Does the lot number match? Are both identity and purity reported, with methods named? Is the test date reasonably recent for the batch? Is the lab identified? If any answer is unclear, ask the supplier. At Bio Elevate, every order ships with its lot-specific COA, and you can request a certificate by lot number from support@bioelevatepeptides.com at any time. For more on the two core tests, read our article on HPLC purity and mass-spec identity.
Educational content for laboratory research. Bio Elevate products are for research use only and are not for human or veterinary use.