Chain of Custody for Laboratory Samples

Chain of custody for a laboratory sample documents every person who handled it and every condition it was held under, from collection at the farm or processing line through transport, laboratory receipt, and final analysis, creating a defensible record proving the sample tested is in fact the same sample collected and that it was not altered, substituted, or compromised in transit, a distinction that matters most when a test result has serious regulatory, legal, or commercial consequences such as a residue violation finding or a disease diagnosis triggering a stamping-out order. A complete chain-of-custody record includes sample identification (matched to the specific batch or animal it was drawn from), collector identity and date-time of collection, preservation method and temperature maintained during transport, and a signed receipt at each handoff point confirming the sample's condition and seal integrity on arrival, with any gap in this record creating room to challenge the result's validity regardless of how accurate the actual laboratory analysis turns out to be. Tamper-evident sample containers and sealed shipping, with the seal number recorded at collection and verified intact at laboratory receipt, are the physical control that makes an unbroken paper chain-of-custody record meaningful rather than merely a documented claim with no physical enforcement behind it. Diagnostic laboratories supporting notifiable disease testing or regulatory residue monitoring typically require strict chain-of-custody compliance as a condition of accepting a sample for official testing, since a result from a sample with a broken chain of custody may not be legally admissible as evidence in a trade dispute or regulatory enforcement action.