Comparison
The same molecule can come from a supplier that publishes a full third-party certificate on every batch, or from one that publishes nothing you can verify. The difference is almost never visible on the product page. It is visible in the paperwork, and this is the paperwork we ask for.
| Criterion | Documented supplier | Typical mid-tier | Repackager or gray market |
|---|---|---|---|
| Third-party lab named on the document | Yes. Janoshik, Finnrick, or an equivalent named on the certificate | Common | Rare |
| HPLC chromatogram published | Yes. The raw trace appears on the certificate | Sometimes | No |
| Mass-spec identity confirmed | Yes. ESI-MS on the batch, not just a purity percentage | Rare | No |
| Endotoxin (LAL) data | Yes, reported in EU/mg | Rarely disclosed | Never disclosed |
| Residual solvent screen | Yes, a GC panel | Rare | No |
| Batch number resolves to a certificate | Yes. The number on the vial finds the document | Partial | No |
| Handling stated for the sequence | Yes. Storage and shipping conditions match what the peptide needs | Sometimes | No |
| Research-use labelling ("Not for Human Consumption") | Yes, on every vial | Usually | Often absent |
A certificate of analysis with no chromatogram is a number, not a measurement. The trace is what lets you see whether the main peak is clean or whether the integration quietly swept a shoulder into it. Ask for the raw trace, the integration table, and the mass-spec confirmation, and check that the batch number on the paperwork is the one printed on the vial.
Read: how to read a certificate of analysis →A research-use-only supplier and a compounding pharmacy operate under different regulatory frameworks and produce material for different purposes. The research supplier characterizes reference chemistry for the laboratory. The compounding pharmacy fills sterile human-use prescriptions under state board of pharmacy oversight. They are not interchangeable, and research material is never a substitute for a medicine.
Read: what research use only actually means →The table above is the summary. The checklist is the version you can work through one line at a time, with the specific question to ask and what a bad answer looks like.