Cannabis lab reports often list compounds with an extra A at the end: THCA, CBDA or CBGA. That letter stands for acid. These are chemically distinct cannabinoid forms, not alternative spellings of THC, CBD or CBG.
What does the A mean?
Acidic cannabinoids contain a carboxyl group. Cannabis plants commonly produce cannabinoids in acidic forms. Over time, or with exposure to heat, some acidic cannabinoids can lose carbon dioxide in a process called decarboxylation, forming their corresponding neutral cannabinoids.
THCA and THC
THCA is the acidic precursor of delta-9 THC. Heat can convert THCA into THC, which has intoxicating effects. This is why THCA content matters when interpreting potential total THC rather than looking at delta-9 THC alone.
CBDA and CBD
CBDA is an acidic precursor associated with CBD-rich cannabis. It is a different molecule from CBD, and the presence of CBDA on a report should not be read as an identical amount of CBD.
CBGA and CBG
CBGA is involved in the plant's cannabinoid biosynthetic pathways and is sometimes described as a precursor to several other acidic cannabinoids. CBG is its corresponding neutral form. The chemistry is more complicated than a simple ranking of stronger or weaker cannabinoids.
Why do percentages differ?
Decarboxylation releases carbon dioxide, so the mass of neutral cannabinoid potentially produced is lower than the original mass of the acidic form. For THCA, laboratories often use the factor 0.877 when estimating potential total THC. This is a theoretical conversion calculation, not a prediction of precisely what any person will absorb.
How should you read a cannabinoid panel?
- Distinguish measured acidic compounds from measured neutral compounds.
- Check whether totals are calculated and how they are defined.
- Do not assume one cannabinoid percentage predicts an experience or a health benefit.
- Remember that laboratory measurements describe the submitted sample.
Related reading: THCA vs. Delta-9 THC and understanding total THC.
Further reading: USDA: Hemp Laboratory Testing Guidelines; USDA ARS: Hemp Descriptors.
For educational purposes only. Cannabinoid content does not establish a product's legal status.