Understanding a Certificate of Analysis: What HPLC and Mass Spec Results Mean

A Certificate of Analysis is only as useful as your ability to read it. Most COAs list two or three test results with lab shorthand and no explanation — this guide breaks down what each one actually measures, so the document means something beyond “a lab was involved.”

HPLC purity — how much of the vial is the target compound

High-Performance Liquid Chromatography separates a sample into its individual components and measures the relative amount of each. The purity percentage on a COA is the proportion of the total sample that matches the target compound’s expected retention time and signal — the remainder is synthesis byproducts, residual solvents, or degradation products. A single purity number without a chromatogram attached is a claim; the chromatogram is the evidence.

Mass spectrometry — confirming identity, not just purity

Purity alone doesn’t confirm what the compound is — a sample can be 99% pure and still be the wrong molecule entirely. Mass spectrometry measures the mass-to-charge ratio of the sample and compares it against the expected molecular weight, which is what actually confirms identity. A rigorous COA reports both: HPLC for purity, mass spec for identity confirmation.

Endotoxin and microbial testing — relevant for reconstituted use in a lab setting

For any compound intended for in-vitro or in-vivo laboratory research, endotoxin levels (typically reported in EU/mg) and microbial contamination screening indicate whether the manufacturing process introduced biological contaminants. These figures matter most for cell culture and animal-model research, where contamination can invalidate an entire experiment’s results.

What a batch-specific COA should include

• The lot number matching the vial in hand
• A named or accredited third-party testing lab, not the seller itself
• A specific test date
• Numeric HPLC purity and mass spec identity results — not just a pass/fail statement

For more on why the lot-specific part matters — and how to spot a COA that’s reused across batches — see our guide on spotting a fake peptide supplier.

Looking up a lot from Amplify

Every batch we sell is tested independently and published against its own lot number:

Look up a batch at amplifyresearchlabs.com/verify →