Sampling and Chain of Custody

The sampling plan should define where the sample came from, how much was collected, and why it is expected to represent the material under evaluation. Testing a convenient vial does not automatically characterize every vial.

Document collection, labeling, sealing, transfers, storage conditions, receipt, and any discrepancy so the tested sample cannot be silently exchanged or detached from the material being evaluated.

A passing result is evidence about the submitted sample under the named method. Claims about uniformity require a sampling and process-control basis in addition to the analytical result.