A sample’s documentary thread
Chain of custody records the journey and transfers of evidence or a sample. NIST’s definition highlights identifying those who handle it, dates and reasons for custody changes. Its glossary has a forensic and evidentiary context; the documentary principle helps explain why knowing only the final result is not enough. NIST: definition of chain of custody
Traceability is a broader concept that allows relationships and history to be followed. Chain of custody focuses on continuity of control and handling. Neither term should be decorative. Their value becomes apparent when records allow a sequence to be reconstructed and explain what happened at each stage.
An imaginary sample’s journey
In a teaching example, someone identifies sample MN-30, notes the declared batch and records its handover. The recipient checks the identifier and documents receipt. Later, the laboratory links the report to its internal code. Every name and code in the example is fictional: they represent relationships that should be traceable, not a certified procedure.
If the identifier’s connection is lost between handover and receipt, a very precise later measurement does not automatically repair that gap. We may know the contents of the container that arrived very well, yet still lack sufficient clarity that it corresponds to the material originally described. Identity and analytical precision are different qualities.
Custody does not mean representativeness
A sample can be perfectly identified and preserved without representing an entire batch. Selection matters when we intend to infer the characteristics of a whole. Eurachem treats sampling and preparation as parts of the measurement process when the result refers to the target material rather than just the portion submitted. Eurachem: sampling uncertainty
Imagine a box containing differently coloured objects. Labelling and impeccably tracking one demonstrates which object travelled, but not that its colour describes the whole box. The analogy is simple and limited, yet clarifies a common confusion: a complete documentary chain and appropriate sampling design answer complementary questions.
What a report should let you reconstruct
Readers will not always have access to every internal record, but should understand who supplied the sample, how it was identified and which material the result refers to. If the laboratory did not carry out sampling, that should be clear. Relevant incidents also matter, as does the scope of what the report claims to represent.
The travelling sample teaches us that confidence does not spring from a single solemn gesture at the end. It is built through verifiable relationships between stages. An honest document can say a great deal about a particular portion while remaining cautious about the whole. That precision lets us use the analysis for what it actually demonstrates and frame the next question better.
Take this with you
Custody protects continuity of identity; sampling determines the wider material a sample can represent.
Sources you can open
The source may be in its original language. English publication does not change the jurisdiction or date discussed.
Follow the thread
Open the cannabinoid encyclopedia
Check the identity, research, uncertainties and documented forms of each compound.