A pre-shipment sample is a sample taken from the actual production lot, after it is made and packed but before it leaves the factory. Testing it tells you whether the goods you are about to receive meet your specification, while you can still stop the shipment.
Yes, you should test it independently, at least for the first orders and for any critical parameter. The supplier's own certificate of analysis is useful, but it is the seller testing its own product.
How it differs from other samples
- An approval or development sample is made before you order, to show what the supplier can produce. It may come from a lab batch, not the plant.
- A pre-shipment sample comes from the commercial lot you are buying, so it shows what you will actually receive.
- A retention sample is a sealed portion of the same lot kept for later disputes. See what a retention sample is.
Who should draw it
The value of a sample depends on where it came from. A sample the factory sends you by courier may be from a different batch, or from the best drum. A sample drawn by an independent person from randomly chosen packages, then sealed in front of them, is much stronger evidence.
Good practice is to draw enough for three sets: one for testing, one kept sealed by you, and one left with the supplier. How to do it properly is covered in drawing a chemical sample correctly.
Where to test it
You have three main options, and many buyers combine them.
- An independent laboratory in India, accredited to ISO/IEC 17025, which is quick because the sample does not need to travel abroad.
- Your own lab, or your customer's, which knows your application best but adds courier time.
- A lab in your own country, useful when results must satisfy your regulator or your customer.
What to test
Test the parameters that matter for your use, not the whole specification every time. Purity or assay, key impurities, moisture and appearance are common choices. For dyes, add strength and shade; for specialty chemicals, add a performance test.
Compare your results with the supplier's COA for the same batch. Large differences point to a testing problem, a batch mix-up or a COA that does not reflect the lot. Our guide to reading a lab certificate helps you judge the report.
Making it part of the contract
Write the sampling and testing into your purchase contract. State who draws the sample, which lab tests it, which methods are used, and that shipment waits for an approved result. If the lot fails, the contract should say what happens next.
Next step
We draw and seal pre-shipment samples at the factory and have lots tested before they ship. To start, book a free sourcing review.