Laboratory Sample Management — Chain of Custody Requirements

Sample Receipt and Logging

Sample chain of custody begins at receipt, with each sample formally logged, uniquely identified, and its receipt condition documented, providing the foundational starting point for a traceable custody record that follows the sample through every subsequent stage of its laboratory life. Receipt logging should capture sufficient information to unambiguously connect the physical sample to its corresponding batch, source, and any special handling requirements, since ambiguity introduced at this earliest stage can propagate confusion through every subsequent step of the sample's laboratory journey.

Storage Requirements

Samples must be stored under conditions appropriate to their specific stability requirements between receipt and actual testing, with storage location and condition documented and, where relevant, monitored, ensuring the sample's condition at the time of actual testing genuinely represents the material as originally received rather than a sample potentially degraded through inadequate interim storage conditions. Samples requiring specific storage conditions, such as refrigeration or light protection, should have this requirement clearly flagged at receipt and consistently honored throughout the entire period the sample remains in laboratory custody before testing.

Custody Documentation

Chain of custody documentation should record every transfer of physical sample custody between individuals or locations, including who released the sample, who received it, and when this transfer occurred, providing a complete, unbroken documented trail from initial receipt through final testing and eventual disposal or retention. A gap in this custody documentation, where the sample's location or custody responsibility is unclear for any period, undermines confidence that the sample tested is genuinely the same, unaltered sample originally received, a concern with genuine legal and regulatory significance beyond simple laboratory record-keeping convenience.

Disposal Requirements

Sample disposal following completed testing, or the conclusion of any required retention period, should itself be documented, confirming appropriate disposal method and authorization, since undocumented or informal sample disposal leaves a gap in the otherwise complete custody record and can raise legitimate questions if a sample's final disposition is later questioned during investigation or audit. Disposal timing should respect any applicable regulatory retention requirements, discussed in the related retained sample program article, ensuring samples are not disposed of prematurely before their required retention period has genuinely concluded.

Sample Identification and Labeling

Robust, unambiguous sample labeling throughout the custody chain is essential to preventing sample mix-up, a genuinely serious laboratory error with potential to produce an entirely incorrect test result attributed to the wrong batch or material, and labeling systems should be designed specifically to minimize this risk, such as through barcode-based identification reducing manual transcription opportunities for error compared with purely handwritten label systems alone.

Handling Split or Subdivided Samples

Where a received sample is split or subdivided for different testing purposes or destinations, each resulting sub-sample requires its own clear identification and custody documentation genuinely traceable back to the original parent sample, since losing this traceable connection between sub-sample and original parent sample undermines the ability to correctly interpret and appropriately connect results generated from that specific sub-sample back to the original, complete sample it actually derived from.

Chain of Custody for Investigational or Retained Samples

Samples specifically retained for potential future investigation, or reference samples set aside supporting a specific ongoing OOS or deviation investigation, warrant particularly rigorous custody documentation, since these samples may need to withstand later, more intensive scrutiny regarding their genuine integrity and unaltered condition should the associated investigation or any subsequent related legal or regulatory proceeding require this heightened level of confidence.

Auditing Chain of Custody Practice

Periodic internal review of actual chain of custody practice against documented procedure helps confirm the program is genuinely functioning as designed in real, everyday laboratory operation, not merely well-documented on paper without consistent genuine adherence in actual daily practice, since a chain of custody program's genuine value depends entirely on its consistent, reliable real-world execution rather than its documented design alone.