How to read a certificate of analysis
A certificate of analysis (COA) summarises the key test results for one batch. This guide explains, in general terms, which sections a typical COA contains and how to interpret them.
Header data: product, batch, date
The top of the document usually states the product name, the batch or lot number, and the test or release date. Together these identify the document with one specific batch.
Identity by mass spectrometry
The identity section compares the observed mass, measured by MS, with the theoretical molecular weight calculated from the molecular formula. A match within the accepted tolerance confirms the identity of the material.
Purity by HPLC
The purity figure is usually reported as an area percentage from an HPLC chromatogram. It describes the share of the main peak within the total peak area — the ratio of the main component to minor components — not the absolute quantity in a vial.
Reading the chromatogram
An accompanying chromatogram shows the main peak and any smaller secondary peaks. Retention time and peak area are the values relevant to the purity result; peak shape can also give an indication of sample quality.
Appearance, content, and storage
Further sections may record appearance (colour, physical state), a water or peptide content figure where relevant, and storage notes, where such tests are defined for the material in question.
Release and signature
A release statement or signature at the end of the document confirms that the batch met the defined specification limits. This entry formally closes out the evaluation of that batch.