Chemical Sample Testing: A Buyer's Guide to Pre-Order Verification

Why Sample Testing Is Non-Negotiable

A sample is the cheapest insurance you can buy in chemical trade. It costs a fraction of one failed container, and it answers the questions that matter: is this the right compound, at the right purity, with acceptable impurities?

What to Test (and How)

• Identity — GC-MS or FTIR confirms the compound matches the CAS number.
• Purity/assay — HPLC or GC with a reference standard.
• Moisture — Karl Fischer titration.
• Physical properties — melting point, density, pH, appearance.
• Application test — run it in your own process; this is the ultimate test.

How to Read Results Against the COA

Your lab result should match the COA within normal tolerance (typically ±0.5% for assay). If it does not:

• Ask the supplier for the original chromatogram, not just the COA summary.
• Confirm both labs used the same method — method differences explain many mismatches.
• Test a second sample from a different batch to check consistency.

Quality-driven suppliers expect their samples to be tested. At Topfine Chemical, we send the batch COA and analytical report with every sample, and we recommend third-party verification for first orders — our export team can coordinate SGS or Intertek testing before shipment.