Cannabinoid content is calculated based on overall sample weight, therefore differences in water weight remaining in flower submitted for testing will cause a variance in apparent cannabinoid values. In an effort to eliminate variance due to water weight, the Colorado Department of Agriculture (CDA) ‘normalizes’ water weight by thoroughly drying hemp samples prior to analysis. To maintain consistency with the CDA’s procedure, we encourage cultivation farms to prepare flower samples according to the CDA’s drying guidelines.
Step One: Selection
- Samples should be selected from the top two inches from a representative mature plant from the hemp field.
- Samples should be taken from female flowering buds.
- Exclude any visible seeds, stems, or fan leaves that may be associated with that sample.
- Exclude male plants.
Step Two: Preparation
- Spread a portion of the hemp sample onto a foil tray. Record the weight of the sample plus the weight of the foil tray.
- Dry the sample at 90 ˚C ± 5 ˚C for approximately 2 hours.
- Allow to cool for at least 30 minutes in a desiccator.
- Record the weight of the sample plus the weight of the foil tray.
- Dry the sample for an additional 15 minutes at 90 ˚C ± 5 ˚C, allow to cool for an additional 30 minutes in a desiccator, and record the weight of the sample and foil tray. Repeat this step until constant weight is achieved.
Step Three: Sieving
- Remove and discard visible seeds and stems.
- Gently work the entire dried and cooled hemp sample through a #8 (2.38mm) mesh screen sieve.
Step Four: Homogenization
- Using a suitable analytical mill, grind sample until a fine, even texture is achieved.
- Transfer to a suitable container to submit for testing.
Colorado Department of Agriculture
Considerations for Laboratory Testings of Industrial Hemp by Keith Wegner