China has hundreds of peptide manufacturers and thousands of traders reselling their output. Prices for what looks like the same product can differ by ten times. Some of that is purity and scale; some of it is a supplier you shouldn't trust with your money or your customers. These are the checks we use when clients ask us to source peptides.
1. Manufacturer or trader?
Ask for the business license and check that its business scope covers chemical or pharmaceutical manufacturing, not just "trading". Traders aren't automatically bad, but you need to know who actually makes the product, because quality and documents come from the factory.
2. The right certificates for what you're buying
- Cosmetic ingredients: ISO certificates, safety data sheets, and test reports for the markets you sell in
- Laboratory reagents: batch certificates of analysis and a clear quality system
- Pharmaceutical ingredients: GMP certification, and for the US an FDA registration and a drug master file. For GLP-1 ingredients going to the US, check whether the manufacturer is on the FDA's green list, because shipments from makers outside it can be detained.
3. A certificate of analysis that means something
A useful certificate of analysis names the exact batch, the test methods and the results. For peptides that normally means:
- HPLC purity, with the chromatogram rather than a single number
- Mass spectrometry confirming the molecule's identity
- Peptide content and water content
- For some uses, endotoxin and microbial limits
Then check it. Send a sample from the same batch to an independent lab. A supplier who resists third-party testing has told you what you need to know.
4. Visit the factory
A video call shows you what the supplier wants you to see. A visit shows you the clean rooms, the equipment, the batch records and the people. If you're buying at scale, it's worth the trip. Our China Facilitator Program arranges factory visits with transport and an interpreter.
Red flags
- Offers of "stealth shipping", fake product descriptions or "guaranteed customs clearance"
- Prices far below every other quote for the same purity
- No batch numbers, or the same certificate for every order
- Communication only through a personal messaging account, with no company website or address
- Pressure to send the full amount up front through untraceable channels
A supplier who offers to hide what's in the box is offering to put the risk on you. When the shipment is seized, the importer loses the goods, not the supplier.
How we help
Our team in China can check a supplier's documents, visit the factory, collect samples for independent testing, and inspect the goods before they ship. Then we handle the freight with paperwork that matches the product. Tell us what you're sourcing and where it's going.
General information, not legal or regulatory advice.