Chain of Custody for Research Samples
Define what needs to be traced
Chain of custody describes the documented movement and control of an identified sample. For research materials, the practical question is whether a reviewer can follow the item from selection through dispatch, laboratory receipt and analysis. The level of formality should match the project and any applicable procedures.
Begin with the sample’s local identifier and its relationship to the original stock. Identify who selected it and whether it represents one vial, several containers or a combined sample. A shipment tracking number records a parcel journey; it does not alone identify everything inside the parcel.
Record meaningful handovers
For each transfer, capture the sender, recipient, date and identifiers checked. Add the observed condition of the packaging and any relevant seal references. Record discrepancies as observations: for example, a broken seal or a label that cannot be read. Do not rewrite uncertainty as confirmation.
The OECD data-integrity publication offers a framework for maintaining understandable records. In a research workflow, a practical custody record should connect with the laboratory submission form and receipt acknowledgement, rather than existing as an isolated signed page.
Document changes to the sample
Opening, dividing, pooling or otherwise preparing material can create new items that need new identifiers. Keep a parent-to-child relationship so that an aliquot does not lose its connection to the original container. Record the responsible person and the reason for creating each derivative sample.
The scope of measurement also matters. Eurachem’s sampling guide treats sampling and preparation as parts of the measurement process. A well-recorded transfer cannot make an unrepresentative sample representative, so the sampling plan deserves attention alongside custody.
Explain what the trail supports
Keep submission instructions, dispatch records and laboratory acknowledgements with the final report. If a discrepancy was resolved by correspondence, include the resolution and who authorised it. Avoid using a generic “chain verified” tick when important stages were not observed or documented.
The research resources can support wider planning, while your local records provide the sample-specific trail. Specify whether the chain begins with supplier stock, your own delivery or an already prepared laboratory sample.
A complete trail strengthens the connection between an item and a result. It does not itself prove chemical identity, purity or suitability for a particular assay. Those questions require appropriate evidence, interpreted within the limits of the sample actually tested.
Related research reading
- Measurement Uncertainty: Reporting More Than a Single Number
- Test Reports and Certificates of Conformity
Explore the research blog and original batch-document library for further context.