A certificate showing 99% purity is a starting point, not proof. Even when an overseas manufacturer makes a legitimate compound, grey-market supply chains add risks that a purity number does not capture. Here are ten reasons to verify independently, whatever the paperwork says.
01
A certificate of analysis supplied by the seller is only as reliable as the seller. A single real result can be attached to many batches, and numbers, dates, and batch codes can be edited. A COA can only be verified when it comes from an independent lab and is tied to the lot number on the vial.
02
Without batch-level filling and volumetric controls, the amount of active compound in a vial can sit well above or below the labeled amount. Purity does not tell you content. Only quantitative testing of the specific lot does.
03
HPLC measures composition. It does not test for bacterial endotoxin or sterility. Material made outside cGMP controls can carry endotoxin or residual process solvents, either of which can compromise cell-based and other sensitive assays.
04
Without mass spec on the actual lot, nothing confirms the vial holds the target sequence. Substitution with a cheaper, structurally similar sequence or a filler is a known risk with unverified suppliers.
05
Lyophilized compounds are sensitive to heat and moisture. International shipping can mean weeks of temperature and pressure swings, and a factory purity result says nothing about the condition of the material when it arrives.
06
Active compounds shipped from overseas are routinely flagged, held, or seized at the border. Time spent in an unconditioned customs warehouse adds further temperature exposure, if the shipment arrives at all.
07
Synthesis relies on strong solvents and reagents such as TFA and DMF. Low-cost processes that skip purification steps can leave trace solvents and metals in the final material, which can interfere with your results.
08
From synthesis to vial, material needs controlled handling and documentation. Grey-market supply chains rarely provide a verifiable record of how raw material was stored and handled, so there is nothing to audit.
09
Verifying overseas material means sending multiple vials from every batch to an accredited US lab for HPLC and mass spectrometry. Once you add lab fees, shipping, and rejected lots, the apparent savings often disappear.
10
Importing active compounds carries customs and regulatory obligations. Overseas manufacturers operate outside US jurisdiction, so recourse for a bad lot is limited and the burden of verification falls on you.
For a shorter checklist, see the supplier evaluation guide.