Overview. A precise analytical result is meaningless if the sample is not representative or has changed before testing. Cannabis flower, oils, extracts and dosage forms require controlled handling from collection through disposal.
Sampling plan
The plan should define locations, increments, tools, sample size, compositing and rationale. It should reflect batch size, containers, process stage and heterogeneity.
Receipt and chain of custody
Samples should be uniquely identified and checked against the request. Seal status, condition, quantity and transport deviations should be documented.
Storage and preservation
Light, temperature, oxygen and moisture can change cannabis samples. Storage conditions should protect the attributes being tested.
Homogenisation and preparation
Flower may require controlled milling; oils may require mixing or warming; extracts may require specific dilution. Preparation should produce a representative analytical portion.
Hold time
Time between sampling, preparation and testing should be justified. Microbiology and volatile analytes may require shorter hold times.
Retention samples
Retention quantity and period should support investigations, regulatory requirements and repeat examination where justified.
Disposal
Disposal should be authorised, traceable and compliant with controlled-substance and hazardous-waste rules.
Practical reference table
| Stage | Main risk | Control |
|---|---|---|
| Collection | Non-representative sample | Approved stratified plan |
| Transport | Temperature or seal failure | Defined conditions and receipt review |
| Storage | Degradation or moisture change | Controlled environment and hold time |
| Preparation | Segregation or analyte loss | Validated homogenisation |
| Retention | Loss of evidence | Inventory and retention period |
| Disposal | Diversion or incomplete record | Authorised witnessed process |
Control and decision path
Frequently asked questions
Why is cannabis flower hard to sample?
Potency, moisture and microorganisms may be unevenly distributed.
What is chain of custody?
Documented traceability of sample identity, transfer and condition.
Can samples be milled before storage?
Only when the impact on stability and representativeness is understood.
How are hold times set?
Through evidence that relevant attributes remain unchanged.
Who may dispose of cannabis samples?
Only authorised personnel under approved legal and quality controls.
Primary references and guidance
- EU GMP Part I, Chapter 6
- WHO Sampling Guidelines
- ISO 17025
- European Pharmacopoeia sampling principles
- WHO GACP
- ICH Q9(R1)
- Applicable controlled-substance legislation
Confirm the current effective revision and national applicability before operational or regulatory use.