Lesson 6.1 · 8 min
Reading a certificate of analysis honestly
Objective: Explain what a COA reports, what it does not prove, and how to spot a questionable report.
A certificate of analysis, usually called a COA, is a document from a lab reporting the results of tests run on a specific sample from a specific batch, tested on a particular date. It is a snapshot, not a permanent guarantee. Reading a COA carefully means checking that it actually corresponds to the product in front of you: batch numbers on the COA and on the container should match. If they don't, the document is not describing what you actually have.
Two common tests appear on COAs. HPLC, high performance liquid chromatography, separates the components of a sample so each can be measured; the result is usually a percentage of how much material detected was the target. Mass spectrometry measures the mass of molecules to help confirm identity, checking whether the molecule weighs what the target should weigh. Neither test is magic, and neither checks for everything. Each method is good at detecting certain problems and blind to others.
A COA does not prove that the vial you hold came from the batch it claims. COAs can be copied, altered, or attached to the wrong product. It does not prove the material has stayed the same since testing; storage and time can change a material. And it only reports what it was asked to test for. A high purity result says nothing about sterility, endotoxins, residual solvents, or heavy metals that were never tested for. Absence of a test is not a passing result.
Work through a report in order: who issued it (a named, contactable laboratory?), what lot does it reference (does it match your vial?), what date was the analysis run, what method was used, and is the actual data shown or only a number? Common warning signs include no laboratory name, no method, no date, a lot number that does not match, and identical reports reused across different products or batches. A real report used dishonestly, attached to every batch after one was tested, is a common pattern. When a report looks questionable, ask the supplier for a report matching your lot, and note the answer.
- Certificate of analysis:
- A lab report describing the results of specific tests run on a sample from a specific batch, at a specific point in time.
- HPLC:
- High performance liquid chromatography, a common lab method that separates the components of a sample so each one can be measured.
- Mass spectrometry:
- A lab method that measures the mass of molecules in a sample, often used to help confirm a substance's identity.
- Lot number:
- An identifier tying a specific batch of material to the records and test results for that batch.