Field by field
| Field | What it means | What to check |
|---|---|---|
| Lot or batch number | Identifies the production run | Must match the vial in your hand |
| Accession number | The laboratory’s internal record ID | Lets you verify with the lab directly |
| Identity, LC-MS | Mass confirmation of the molecule | Look for the trace, not just “confirmed” |
| Purity, HPLC-UV | Target peak area over total peak area | The chromatogram shape matters more than the figure |
| Net content | Actual measured fill in mg | Compare against the label quantity |
| Endotoxin, USP <85> | Bacterial endotoxin, LAL assay | Whether it was run in duplicate, and assay sensitivity |
| Microbial, PCR | Screen for microbial DNA | Not a sterility test. See below. |
The three-step verification
- Match the lot number on the certificate to the lot printed on the vial. If they differ, you have a document about a different object.
- Confirm the laboratory is independent of the seller. A report on the seller’s own letterhead is an in-house result, which is a different claim and should be labeled as one.
- Look for the method and the trace. A table of percentages with no chromatogram cannot be evaluated by anyone, because the impurities live in the shape of the curve.
Where a certificate carries an accession number or search code, you can verify it with the issuing laboratory directly rather than taking the seller’s word. Ask for that before you buy, not after.
The distinction almost everyone gets wrong
Microbial screening is not sterility
USP <85> is the bacterial endotoxin test. A PCR microbial screen looks for
microbial DNA. USP <71> is the actual sterility test, a roughly fourteen‑day
dual‑media culture that consumes sample units. A PCR pass reads like sterility and is not one:
it can miss viable organisms below its detection floor and can equally flag dead DNA. If a
supplier lists sterility among what they test, ask to see the USP <71> report.
What a certificate does not tell you
- Sterility, unless USP <71> was specifically run
- How the material was handled after testing, or how long it has been on a shelf
- Residual solvents, unless separately assayed
- Anything about the vial you hold, if the lot does not match