Accepted answer
The part that matters: the question to ask is not whether a vendor is good but what evidence exists, of what kind, about which lots, from whom. Reputation is a compression of that evidence and it compresses badly.
On declarations: the accurate description of a research reference material is a research reference material, and accuracy is both the legal position and the practical one. A declaration that misdescribes the contents converts a customs question into a different kind of question, and it does so on a document with your name on it.
Certificate red flags and what each implies
| Observation | Implication | How to check |
|---|
| Lot number not on the vial | Certificate cannot be tied to your material | Photograph vial and certificate together |
| No method section | The number is not reproducible | Request column, gradient, wavelength |
| Purity to two decimals, no chromatogram | False precision | Request the trace |
| Test date before manufacture date | Certificate belongs to a different lot | Compare dates |
| Identical figures across lots | One certificate reused | Compare two lots side by side |
| “Sterile filtered” with no sterility test | Process claim substituted for a result | Ask for the sterility report |
Lot-to-lot content variation of nine per cent between two nominally identical lots, both within a stated specification, is the single most common finding in independent testing and the least discussed. It is not fraud; it is the consequence of a fill process controlled to a tolerance rather than to a target. It is also the reason a per-lot content assay is worth more than a per-supplier reputation.
Independent testing costs have been stable enough over the past two years that amortisation arithmetic across a lot is worth doing before choosing a lot size, and the numbers usually favour a larger lot tested once over several small lots tested never.
One qualification: independent testing tells you about the vial you sent. It tells you about the vial you kept only under an assumption of homogeneity that nobody has tested.
Assume no recourse and plan accordingly. That assumption is both prudent and, in this context, accurate.
4Two of us worked through this independently and arrived here, so it is at least reproducible. – nkem_obiora 15 days ago 3Worth adding that the method section is where the answer usually is. – marta_okonkwo 9 months ago add a comment