Why is testing cannabis potency a challenge?

Cannabis is a tough product to analyse due to its complex composition consisting of hundreds of active compounds.  

Natural Variation

Natural variation in composition can cause huge differences in potency between plants, between different buds from the same plant, and even within the same bud.

No two cannabis flowers are the same. The potency of one cannabis flower will not adequately represent other flowers from the same batch or from the same plant.

Potency analysis is challenged by the plant’s non-homogeneity expressed in both physical and chemical properties.

Physical

Physical non-homogeneity refers to flowers featuring varying sizes and irregular shapes. Some areas may even be void of active compound molecules of interest.

Chemical

The chemical non-homogeneity of cannabis refers to the uneven distribution of these compounds in the flower. Even though over 90 percent of cannabis active ingredients are contained in the trichomes on the flower’s surface, these are not distributed evenly.

Image analysis shows that trichomes are not dispersed equally throughout a flower bud.
Even ground material does not guarantee equal distribution of active compounds.
One area can have a higher trichome concentration than another.

Grinding a sample before analysis is the traditional method to overcome the non-homogeneity, but:

Grinding speeds up potency degradation and leads to loss of efficacy.

Laboratory tests confirm that grinding does not necessarily yield representative samples.

The commercial value of ground material is at least 50% lower than the whole flower.

Reaching a conclusion based on measuring a single sample, one flower, is not recommended.

How many samples is enough?

Depends on the batch size, but in principle results from three samples is the minimum for obtaining a representative potency result for the smallest of batches.