Chain of Custody for Assay Samples: Audit-Ready QA/QC for Modern Exploration

Chain of custody is the unbroken documented trail showing where a sample has been, who has handled it, and what has been done to it, from collection through to assay. Both JORC 2012 and NI 43-101 require it, and auditors flag custody breaks as one of the most common findings.

The QA/QC trio is blanks, certified reference materials (CRMs), and field duplicates, inserted at agreed frequency into the sample stream. Their results in the lab tell you whether the data are reliable. But they only work if the samples themselves are demonstrably the samples they claim to be, which is where chain of custody comes in.

Paper sample tags and field notebooks are still common, but they introduce transcription errors, loss, and ambiguity. Digital field capture, barcoded sample bags, geo-tagged photos at each handover, electronic shipping manifests, and lab-acknowledged receipts, closes the gaps. Crucially, a digital audit trail makes the QP's job easier when the technical report comes due.

Laboratories should be ISO 17025 accredited. Their internal QA records should be available on request, and any non-standard results should trigger documented re-assays.