Quality & Testing
Peptide Testing Glossary: Terms You’ll See on a COA
Test reports are full of abbreviations. Here is what the common terms mean, in plain language.
| Term | What it means |
|---|---|
| Batch (lot) number | An identifier for one production run. A COA only describes the batch it names. |
| Certificate of analysis (COA) | The laboratory report listing the tests run on a batch and their results. |
| Third-party testing | Testing by a laboratory that is independent of the seller. |
| HPLC | High-performance liquid chromatography. Separates the components of a sample so each can be measured. |
| Chromatogram | The graph HPLC produces: a line with a peak for each component that emerged from the column. |
| Retention time | How long a component took to emerge from the HPLC column. It helps identify peaks but is not proof of identity. |
| Peak area / area percent | The area under a peak. Purity is usually reported as the main peak’s share of the total area. |
| Mass spectrometry (MS) | A method that measures the mass of molecules, used to confirm a peptide’s identity. |
| m/z | Mass-to-charge ratio, the quantity a mass spectrometer actually measures. |
| Molecular weight | The mass of one mole of the compound, in g/mol. The measured mass should agree with the theoretical value. |
| Net peptide content | The share of the powder’s weight that is actual peptide, as opposed to water and counter-ions. |
| Counter-ion / TFA salt | A small ion, often trifluoroacetate, that accompanies a peptide after purification and adds to the powder’s weight. |
| Lyophilized | Freeze-dried: water has been removed from a frozen sample under vacuum, leaving a dry powder. |
| Karl Fischer titration | A method for measuring water content. |
| Endotoxin (LAL) test | A test for bacterial endotoxins, relevant to contamination. |
| Sterility testing | A test for living microorganisms in a sample. |
| Research use only (RUO) | A label meaning a product is intended for laboratory research and is not for human or veterinary use. |
For laboratory research use only. Not for human or veterinary use. See our Research Use Only page.