The research-peptide market is uneven. Some suppliers test every batch and document it. Others copy a purity claim onto a label and hope. This is a due-diligence checklist for judging a supplier on evidence rather than marketing.
Lot-specific, third-party COA
The single most useful signal. The supplier should provide a Certificate of Analysis tied to the exact batch you received, run by an independent lab, showing HPLC purity and mass-spectrometry identity. A generic or reused COA is worse than none, because it implies documentation that does not exist.
Independent testing, not just in-house claims
In-house purity claims are unverifiable. Third-party testing means an outside lab, with no stake in the result, confirmed the numbers. Ask who runs the testing and whether the report names them.
Transparency you can check
Real documentation has batch numbers, test dates, and named analytical methods. If those details are absent or never change between orders, treat the claims as unsupported.
Handling and shipping
Ask how material is stored before dispatch and how temperature-sensitive items are packed. Lyophilized powder tolerates brief transit at room temperature; the point is whether the supplier understands and manages the difference.
Consistency across batches
A supplier worth keeping produces the same purity batch after batch. One good COA is a start. A track record of them is the actual signal.
Red flags
- No COA, or a generic one not tied to your lot.
- Marketing that describes human benefits, dosing, or treatment. Beyond the compliance problem, it signals
a seller who is not operating as a research supplier.
- No lot numbers, no test dates, no named testing lab.
- Purity claims with nothing behind them.
SynproLabs tests every batch by third-party HPLC, publishes lot-specific COAs, and holds the research-use line in how it describes its products. Those are the standards this checklist is built on.
For laboratory research use only. Not for human consumption.