November 2, 2026 · 2 min read
How to Read a Certificate of Analysis
Purity, identity, lot number and dates: a line-by-line guide to what a COA tells you, and what to check before you rely on one.
A certificate of analysis (COA) is the lab's record of what it found when it tested one specific sample. It is the single most useful document you can ask a supplier for, as long as you know what to look for. Every report we publish is in our COA Library.
1. Who tested it, and for whom
The top of the report names the testing laboratory, a certificate number and, on some reports, a verification code you can check with that lab. It also says who the report was issued to. An independent lab, a unique certificate number and a way to verify it are the first signs a report is genuine.
2. What was tested
Look for the compound name and the labeled amount, for example "NAD+ 1000mg". This should match the product and size you are buying. A report for a 10 mg vial says nothing about a 30 mg vial from a different run.
3. Lot number and dates
The client reference or lot number ties the report to one production batch. The dates show when the lab received the sample, when it was tested and when the report was issued. A recent date and a lot number that matches your batch matter more than any single result.
4. The summary table
Most reports put the results in one table with the same columns:
| Column | What it means |
|---|---|
| Test | What was measured, such as purity or identity |
| Result | What the lab found, such as 99.84% |
| Method | How it was measured, such as RP-HPLC or mass spectrometry |
| Specification | The pass mark, such as ≥ 99% |
| Outcome | Pass, fail, or N/A where no limit applies |
5. The tests you will usually see
- Purity (RP-HPLC): the share of the sample, by peak area, that is the main compound. At the time of writing, our published reports range from 99.12% to 99.86%.
- Identity (mass spectrometry): confirms the molecule's measured mass matches the expected one. "Consistent" or "within tolerance" is the result you want.
- Endotoxin (LAL): measures bacterial endotoxin in endotoxin units per mL. It matters for cell-based work.
- Heavy metals (ICP-MS): screens for trace metals.
- pH: the acidity of the tested solution, against a stated range.
- Net content: how much material was actually in the vial compared with the label.
6. The detail pages
After the summary, most reports include the chromatogram (the HPLC trace), the mass spectrum and notes from the analyst. A single tall peak in the chromatogram with only small peaks around it is what a high purity figure looks like.
A quick checklist
- The compound and amount match what you are buying.
- The lot number matches your batch.
- The report is recent and from an independent lab.
- Purity and identity both pass.
- The certificate number or verification code checks out with the lab.
All Powerhouse Research Co products are for in-vitro laboratory research only. A COA documents a sample's composition; it says nothing about suitability for any other use.