How to Read a Certificate of Analysis (COA) for Research Peptides

A Certificate of Analysis (COA) is the most important document that comes with any research peptide. It shows what was tested, how it was tested and what the results were. Here is how to read one.

1. Product name and batch (lot) number

Every COA should name the compound and give a batch or lot number. That number should match the label on your vial. A COA without a batch number, or one that is reused for every batch, tells you very little.

2. HPLC purity

High-Performance Liquid Chromatography (HPLC) separates the contents of a sample and measures how much of it is the target peptide. The result is shown as a percentage, for example 99.2%. For research-grade peptides, look for 98% or higher, ideally 99%+. The COA will usually include a chromatogram: a graph with one tall main peak (the peptide) and only very small peaks elsewhere (impurities).

3. Mass spectrometry (identity)

HPLC tells you how pure a sample is, but not what it is. Mass spectrometry (MS) confirms identity by measuring the molecular weight. The COA should list the expected (theoretical) mass and the observed mass, and the two should match closely.

4. Test date and laboratory

A good COA shows when the test was carried out and by which laboratory. Independent third-party testing is the gold standard.

5. Appearance and form

Most research peptides are supplied as a white lyophilised (freeze-dried) powder, and the COA usually confirms this.

Red flags

Be cautious of:

• no batch number;
• no chromatogram;
• purity stated with no testing method;
• no mass spec data; or
• the same COA used for every product.

At Ligaya Labs

Every batch we supply is tested by HPLC and mass spectrometry, and the batch-specific COA is available on our Testing & COA page so you can check it against your vial before use in the laboratory.