Two questions, two tests
A useful certificate answers two questions about a sample. How much of it is the main compound? And is that main compound the one on the label? The first is purity. The second is identity. They are measured in different ways.
HPLC measures purity
High performance liquid chromatography, or HPLC, pushes a dissolved sample through a packed column under pressure. Different molecules travel through the column at different speeds, so they reach the detector at different times and show up as separate peaks on a chart called a chromatogram.
Purity is the main peak’s share of the total peak area. If almost all of the signal sits in one peak, the sample is mostly one substance.
What HPLC cannot do on its own is say what that substance is. A sample of the wrong compound can still produce a single clean peak.
Mass spectrometry confirms identity
Mass spectrometry, or MS, turns molecules into charged particles and measures their mass. Each compound has a known theoretical mass. If the observed mass matches the expected one within the method’s tolerance, the compound is what the label says.
Mass spectrometry confirms what is present. It is not a purity measurement, so a sample can pass identity and still carry other substances.
Why a certificate needs both
| Question | HPLC | Mass spectrometry |
|---|---|---|
| How much of the sample is the main compound? | Yes | No |
| Is the main compound the one on the label? | No | Yes |
| What the report should show | The purity figure and the chromatogram | The expected and the observed mass |
Purity without identity could describe a very pure sample of the wrong thing. Identity without purity says nothing about what else is in the vial. Together they describe the lot.
What to look for on a report
- Each result names the method used to get it.
- The chromatogram and the mass spectrum are attached, not just the numbers.
- The identity result shows the expected and the observed value.
- The lot number matches your vial or your order.
- The laboratory is named, and you can confirm the report with them directly.
Method Biolabs has its lots tested for purity by HPLC and for identity by mass spectrometry at Freedom Diagnostics, an independent laboratory in Franklin, Tennessee. Each lot’s full report goes up on our Certificates page as soon as its results are in.
This guide explains how to check documentation. It is not advice on using any product. Method Biolabs supplies reference materials for laboratory research only: not for human or veterinary use, and no dosing or protocol guidance.
