Retain Samples, Referee Samples and Laboratory Disputes in Bulk Salt

A difference between a supplier COA and the buyer's incoming test does not automatically prove which result is wrong. Sampling, homogeneity, method, preparation and laboratory practice can all affect results. A dispute procedure should therefore exist before the first issue.

Why keep a retain sample?

A sealed sample verified to represent the same lot provides a common reference for later retesting. Its source and sampling method should be documented.

Seal and label the sample

Lot, date, sampler, quantity and seal number can be recorded on the label and sample form. An opened or unidentified sample is weak evidence in a dispute.

Check method differences first

If two laboratories use different preparation or analytical methods, the results may not be directly comparable. Align method and units before deciding on a retest.

Using an independent referee laboratory

The contract can define a competent third laboratory for referee testing where needed, including which sample is submitted and how the result is used.

Retention period and storage

The retention period can reflect product risk, contract requirements and intended use. Samples should be protected from moisture and contamination.

Dispute file

• Lot number
• Original COA
• Buyer test result
• Test method
• Sampling record
• Seal number
• Retain sample
• Retest result
• Referee result if used

Related guides

• Rock Salt Sample and Laboratory Report Evaluation
• Nonconformity, Complaints and CAPA
• Bulk Salt Specification Acceptance Limits