A beginner’s guide
How to read a peptide COA
A COA (certificate of analysis) is a report of test results for a sample. Learn what to look for, what the numbers mean and what to ask if something is missing.
Start here
Five things to check.
One at a time.
You do not need to understand every line. Tap a line on this example to see what it means.
Certificate of analysis
Made-up details and results for this guide.
A simplified example. Real reports vary in layout and tests.
Is it the right product?
Start with the name. It should match the product you are asking about. If the names differ, ask the supplier to explain before you rely on the report.
“Does this report cover the exact product I am ordering?”
Is it the same batch?
A batch is a group made together. The report should connect to the batch being offered to you. A report for a different batch does not tell you about yours.
“Will the batch number on my order match this report?”
What does the percentage mean?
This test separates substances in the sample and records a signal. The 99% figure is the share of that signal assigned to the peptide. It does not measure everything in the vial or tell you how many milligrams of peptide are present.
“Is this only a purity result, or was the amount of peptide measured too?”
Was the product’s identity checked?
An identity test helps check whether the sample is the named peptide. You may see “MS” or “mass spectrometry”: a test that measures molecular mass. A matching mass helps, but it is not complete proof on its own.
“What test was used to check the identity, and what did it show?”
Who is behind the report?
Look for the testing lab, report number and test date. A supplier’s logo does not mean an independent lab tested it. To check a report, find the lab’s own contact details and ask them to confirm the report number.
“Which lab did the testing, and how can I verify this report with them?”
These checks help you read a report. They do not verify that it is genuine or that a product is safe.
A few common questions.
What if the name or batch number is missing?
Ask the supplier for the full report and how it connects to the batch being offered. A cropped screenshot or a percentage on its own is not enough to make that connection.
What is the chart with all the peaks?
It is called a chromatogram: a graph of signals recorded during a laboratory test. In a typical HPLC purity test, the lab compares these signals to calculate the reported percentage.
You do not need to work out the peak areas to do the five checks above. If the chart and the reported result are unclear, ask the testing lab to explain them.
Further reading: Bachem: quality control of amino acids and peptides
Does a COA prove the product is safe?
No. It reports only the tests listed, on the sample tested. A purity result does not show that a product is sterile or safe to inject. A test that is not listed should not be assumed to have passed.