Chain of Custody for Laboratory Samples

Chain of Custody for Laboratory Samples: Chain of custody documents who handled a sample, when, where and under what conditions. It is particularly important when test results may inform regulatory, legal or contractual decisions.

Why this topic matters: A technically accurate result may still be disputed if sample identity, seals, transfers or storage conditions cannot be demonstrated.

Step 1 — Scope the problem: Assign unambiguous identifiers at collection and connect them to the sampling plan, location and collector.

Step 2 — Apply the method: Record custody transfers, seal condition, temperatures, storage locations and access permissions as required by the method or contract.

Step 3 — Sustain the result: Reconcile sample aliquots, retained portions and disposal so the complete evidence chain can be reconstructed.

Practical laboratory example: An environmental water sample arrives with a broken seal and no transfer signature. The laboratory should document the discrepancy and consult its acceptance rules before proceeding.

Common errors: Backdating signatures, using ambiguous handwritten IDs or relying on courier memory for missing handoffs. Procedures need to withstand real laboratory conditions and staff turnover, rather than merely look complete during audits.

Evidence to keep: Collection sheets, transfer receipts, seals, LIMS audit trails, storage logs and exception approvals. The records should allow an independent reviewer to reconstruct how and why technical decisions were made.

Action to take this week: Trace one closed sample case without speaking to the original collector and identify missing links. Assign an owner and decide what evidence will demonstrate improvement.

Authoritative references: ISO/IEC 17025:2017, sampling requirements and relevant customer or regulatory protocols. Always obtain the applicable standard and check its scope before interpreting this educational overview as an accreditation requirement.