A certificate of analysis (COA) is a report that records what a laboratory measured in one specific sample, using one specific method, on specific dates. It is a statement of analytical data. Reading it well means knowing what each field answers, and just as importantly, what it does not.
This guide walks through a COA field by field, using the layout of an ANALITIKA certificate as the example.
What a certificate of analysis is (and what it is not)
A COA is a record of measurements. It describes the sample as it was received, the method that was applied, and the numbers that method produced.
It is not a guarantee about a whole production batch, a statement about how a material should be used, or an approval of any kind. It speaks only about the sample that was tested. If the sample was taken from a larger lot, the certificate cannot tell you how representative that sample was.
Keeping this scope in mind prevents most of the misreadings that cause confusion later.
The header fields: sample ID, report number, dates, method
The top of a certificate identifies what was tested and when. These fields look administrative, but they are what make the document traceable.
- Compound name: the name of the material as submitted and as tested.
- Report number: a unique identifier for the certificate. On an ANALITIKA COA it takes the form ACT-##### and is never issued twice. The certificate also shows the order number it came from.
- Sample ID: the reference that links the physical sample to its data. If a lab cannot trace a result to a sample ID, the result has little value.
- Dates: an ANALITIKA certificate shows four: when the test was requested, when the sample was received, when it was tested and when the report was issued. A gap between these dates is normal, but they should be present and in a sensible order.
- Method and instrument: the technique used and the equipment it ran on. For ANALITIKA this is reversed-phase high-performance liquid chromatography (HPLC) with UV detection. If you are new to the technique, our HPLC explainer covers the basics.
A certificate that omits the method, or describes it only vaguely, makes it hard to judge how much weight the numbers deserve.
Reading the results: purity, mass and the chromatogram
The results are built on the chromatogram, the plot HPLC produces, which is printed on the certificate. Two ideas from it do most of the work.
Retention time is how long the target compound took to travel through the column and reach the detector. You read it from the time axis of the chromatogram. It is used to recognise the compound by comparison with a certified reference standard run under the same conditions. For a closer look at peaks, see HPLC Chromatogram Explained: How to Read the Peaks.
Peak area is the size of the signal under each peak. It reflects how much of each detected substance passed the detector.
The headline figure, shown in the content analysis section of the certificate, is chromatographic purity (%). It compares the target peak with everything else detected: the target peak area divided by the total peak area, multiplied by 100.
Notice what this figure is: a statement about the proportion of detected signal. It is a relative measure, and it depends on the method, the detection wavelength and the integration settings used.
Purity vs identity vs potency: what each one answers
These three words are often used as if they were interchangeable. They are not.
- Purity asks how much of what the detector saw belongs to the target compound, compared with other detected substances.
- Identity asks whether the main peak is the compound it is claimed to be. On an ANALITIKA COA, identity is supported by retention-time comparison against a certified reference standard. This supports identity; it is not the same as a mass confirmation.
- Potency is a biological concept. It describes how strongly a material produces a biological response. ANALITIKA does not measure potency, and a COA from an HPLC method cannot tell you anything about it.
A certificate can answer the first two questions well and still be silent on the third. That silence is not a gap in the report. It reflects what the method measures.
Why a high purity figure does not equal net content
This is the most common misunderstanding about purity figures. A result of 99% chromatographic purity does not mean the powder is 99% target compound by weight.
Chromatographic purity only compares the substances the detector responds to. Many components of a real powder are invisible to a UV detector or sit outside the comparison:
- Water absorbed or bound in the material
- Salts and counterions that accompany the compound
- Residual materials that do not absorb UV light
A powder can show very high chromatographic purity and still contain a meaningful fraction of water and counterions by weight. The purity figure describes the quality of the signal, not the composition of the powder.
This is why an ANALITIKA COA also reports measured mass, expected mass and fill accuracy. These fields address a different question: how much material is present compared with what was stated. Read them alongside the purity figure, not instead of it.
The limits of a COA: analytical data only
A certificate reports data. It does not interpret that data for any particular use, and it does not make claims about what a material is suitable for.
Several limits are worth remembering:
- The results apply to the sample received, not automatically to other units or lots.
- Purity is method-dependent. A different method or detection wavelength could give a different figure.
- HPLC-UV detects substances that respond to UV light. Something with no UV response will not appear on the chromatogram.
- Identity by retention-time match is supported, not proven in an absolute sense.
None of these limits make a COA less useful. They make it more useful, because a reader who understands them will ask better questions of any certificate.
How to confirm a certificate is genuine
A certificate is only worth reading if it is authentic. Logos, formatting and QR codes can all be copied from a genuine document onto an altered one, so none of them proves anything on its own.
ANALITIKA certificates are sealed when issued, and each carries a data fingerprint. At www.analitikatesting.ca/verify you can upload the COA PDF. The file is fingerprinted inside your own browser and never uploaded. The fingerprint is then compared with the one recorded when the certificate was sealed. If even one character in the file has changed, the check fails.
For a full explanation of how this works and why it matters, read COA Verification: How to Tell if a Certificate Is Real.
If you want to see which analyses we offer, the services page lists them, and the testing page lists the compound categories we analyse.