Potency testing quantifies the cannabinoids in a sample. The standard approach is high-performance liquid chromatography with UV detection (HPLC-UV), which measures acid and neutral cannabinoids separately without heating them. The lab weighs a homogenised portion, extracts it with solvent, runs it against calibrated reference standards and reports each compound and the calculated totals.
In practice
Results depend heavily on steps before the instrument: which buds were sampled, how well they were ground and mixed, whether moisture was corrected, and how the lab calibrates. Jikomes and Zoorob (2018) showed that results in a regulated market differed systematically between labs, and Schwabe et al. (2023) found many retail labels well above independently measured values. For a home grower, one test of a well-mixed sample of several buds is far more useful than a single top cola.
Don't confuse with
- Terpene test: measures aroma compounds, usually by GC.
- Genotyping: reads DNA, can predict chemotype class but not percentage.
- Home test kits: colour or thin-layer kits give rough estimates, not COA-grade numbers.
Myth check
A higher number from a different lab is not proof of a better plant. See buyer beware.
A cannabinoid is any compound that binds the body's cannabinoid receptors or shares the typical cannabis terpenophenolic structure; the plant-made ones are phytocannabinoids such as THCA and CBDA.HPLC (high-performance liquid chromatography) separates compounds dissolved in a liquid under pressure; it is the standard cannabis potency method because it measures acid cannabinoids without heating them.Acid cannabinoids (THCA, CBDA, CBGA) are the carboxylated forms the plant makes; neutral cannabinoids (THC, CBD, CBG) form when heat or time removes the carboxyl group.The dense, elongated cluster of flowers that forms at the end of a stem or branch; the main cola tops the leader.A terpene test measures the individual terpenes and total terpene content of a sample, usually by GC-FID or GC-MS, reported in % w/w or mg/g.Gas chromatography (GC) separates volatile compounds in a heated gas stream; it is used for terpenes and residual solvents and decarboxylates acid cannabinoids in its hot inlet.Genotyping is reading a plant's DNA at selected markers to identify it, compare it with other plants, check sex or chemotype, or estimate its ancestry.A chemotype is a plant's chemical phenotype, in cannabis usually its dominant cannabinoid class: THC-dominant (I), mixed (II), CBD-dominant (III), CBG-dominant (IV) or cannabinoid-free (V).Total THC is a calculated figure, Δ9-THC plus 0.877 × THCA, estimating the maximum THC a sample could yield after full decarboxylation.A COA (certificate of analysis) is a lab's signed report of what it measured in a specific sample, such as cannabinoids, terpenes, moisture and contaminants, with methods and limits.Homogenisation is grinding and mixing a sample so every portion the lab tests represents the whole; together with representative sampling it often matters more than the instrument.Measurement uncertainty is the quantified range around a lab result within which the true value is expected to lie, typically stated as ± a value at about 95% confidence.Label inflation is the gap between the potency printed on cannabis packaging and what independent testing finds, a documented, mostly upward bias in retail THC claims.
