How to read a COA and a chromatogram
Reading a certificate of analysis and an HPLC chromatogram: peak, retention time and purity in percent.
What a COA shows
A certificate of analysis summarises the measurement results of a batch. At the top are the name of the substance, the batch number and the date. Below that are the results of tests such as HPLC and mass spectrometry, often with a graph called a chromatogram.
Reading a chromatogram
An HPLC chromatogram is a graph with time on the horizontal axis and signal on the vertical axis. Every substance that passes through the instrument gives a peak. The position of the peak on the time axis is called the retention time: the number of minutes the substance takes to travel through the column. The main substance gives the largest peak.
Purity in percent
Purity is calculated from the area under the peaks. The area of the main peak divided by the total area of all peaks gives a percentage. A value of, for example, 99 percent means that the main peak covers almost the whole signal and small peaks only a small part. This lets you read at a glance how pure a batch is.
Every batch with its own COA
Certificate of analysis per batch and discreet shipping from the EU.