Start with who wrote it
The report should name the lab that ran the tests, with an address you can look up. A supplier's logo at the top is fine. A report with no lab named on it is not a third-party report.
If the lab claims ISO/IEC 17025 accreditation, check it. Accreditation is granted by an accreditation body, such as A2LA or ANAB in the US, UKAS in the UK or DAkkS in Germany, and each one publishes a directory of the labs it accredits. The entry lists the lab's scope: the specific tests it is accredited for. Make sure the test on your report sits inside that scope. A lab can be accredited for one method and not for another.
Check what was tested
Look for the sample description, the sample ID the lab assigned, the date the sample arrived and the date it was tested. The product name on the report should match the label on your vial character for character, including the stated amount.
Every result needs a method and a limit
A useful result has three parts: the method used, the acceptance limit, and the measured value.
| Test | Method you should see | Result you should see |
|---|---|---|
| Purity | Reversed-phase HPLC with UV detection, usually at 214–220 nm | Main peak as a % of total peak area |
| Identity | Mass spectrometry, ESI or MALDI | Observed mass next to expected mass |
| Endotoxin | LAL or recombinant factor C assay | EU per mg, with the limit used |
A purity figure with no method next to it is a number without context. So is a result with no limit to judge it against.
Look at the raw data
A good report includes the chromatogram and the mass spectrum, not just a summary table.
- Chromatogram. One tall main peak on a flat baseline, with a peak table listing retention times and area percentages. The purity on the front page should equal the main peak's area in that table.
- Mass spectrum. The observed mass should sit within the lab's stated tolerance of the expected mass. Electrospray often shows several peaks for one molecule, one per charge state, which the lab converts to a single molecular mass.
Look for signs of editing
Doctored reports tend to give themselves away. Watch for:
- Fonts, spacing or alignment that change partway down the page.
- A chromatogram that looks identical on reports for different products.
- Purity quoted to three decimals with no chromatogram behind it.
- A test date earlier than the date the sample arrived.
- No signatures, or no named analyst or reviewer.
- A lab you can't find, or one whose website doesn't list the test.
Ask the lab
Most accredited labs will confirm whether they issued a report if you send them its report number. It takes one email, and it is the strongest check there is, because it moves the question from the supplier to the lab.
The short version. A named lab you can look up, accreditation that covers the test, a method and a limit for every result, raw data that matches the summary, and a lab that will stand behind the report.