A Certificate of Analysis is the document that says “this specific batch of this specific chemical meets this specific specification.” Every drum, every IBC, every ISO tank that leaves a Chinese factory should travel with a COA tied to the batch number stamped on the package. Without a COA you have a chemical of asserted identity but no third-party-verifiable proof it meets your spec.
What a real COA must include
- Producer name and address, the actual factory, not a trading company.
- Product name and CAS number, confirming what the substance is.
- Batch number, must match the production batch on the drum / IBC label.
- Production date, relevant for shelf-life-sensitive products (e.g. certain peroxides, some catalysts).
- Specification table, assayed parameters (purity, moisture, ash, heavy metals, residual solvents, etc.) with the agreed acceptance range.
- Actual results, what the batch tested to, parameter by parameter.
- Test methods cited. USP, FCC, GB/T, ASTM, ISO, or in-house method numbers. “Internal” without a method number is a soft signal.
- Date of analysis and lab signature.
If any of those eight is missing, the COA is incomplete. Demand the missing item before you wire the balance payment, not after.
Factory COA vs third-party COA
A factory-issued COA is the manufacturer certifying their own product. A third-party COA is an accredited lab, SGS, Bureau Veritas, Intertek, TÜV, testing a sample drawn from the same batch and issuing an independent certificate. Both have a place. Factory COAs are sufficient for routine repeat orders from a factory you know. Third-party COAs are essential for first orders, for high-value cargo, for any DG product that will fly under the buyer’s regulatory scrutiny in the destination country, and for anything where the spec failure would be expensive (food-grade, pharma-grade, electronic-grade).
What we verify before a container leaves
For every chemical shipment we book out of Shanghai or Qingdao, the factory’s COA arrives at our office before the SGS pre-shipment inspection is scheduled. We compare three things: the COA results against the contracted spec, the batch number on the COA against the batch numbers on the actual drums, and the production date against the projected transit time (you do not want a shelf-life-12-months product produced 11 months before vessel ETA). If those three line up, we authorise the inspection. If they don’t, we go back to the factory before scheduling SGS, there is no point inspecting a batch that already failed the paperwork test.
COA is not a substitute for inspection
A COA tells you what the lab measured on the sample they drew. A pre-shipment inspection tells you what is actually in the drums and that the drums actually contain what the labels say. Both are worth the money. Either alone is half the picture. Most expensive supplier failures we have seen across twenty years involved a clean COA on paper and a contaminated container in reality.
Per-batch versus blanket COAs
Chinese factories sometimes provide a blanket COA referencing a generic specification rather than a per-batch lab report. A blanket COA reads as compliant on paper but does not reflect the actual cargo. Specify per-batch COA on the proforma invoice and confirm that the COA test date is within 30 days of the cargo loading date. A COA dated three months before loading was not run on the cargo you are buying.
Lab certification and traceability
Independent third-party lab certification adds a layer of verification beyond the factory’s in-house COA. SGS, Bureau Veritas, Intertek, and TÜV all run chemical analytical labs in major Chinese ports. For volume cargo or specialty grade applications, an independent lab COA on the actual loaded cargo costs USD 200 to USD 800 per cargo and provides a trustworthy record if a downstream quality dispute arises. The factory’s in-house COA should match the independent lab result within reasonable analytical tolerance; meaningful divergence is a red flag worth investigating before paying the balance against the bill of lading.
Related documents
The MSDS is the safety data sheet (hazard properties, handling). The COA is the quality certificate (this batch, this spec, this result). The TSCA certification is the US import compliance statement. All three travel with the cargo and serve different purposes.